[Index]
Monthly Global Tropical Cyclone Summary September 2006
[Summaries and Track Data] [Prepared by Gary Padgett]
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Monthly Global Tropical Cyclone Summary September 2006 [Summaries and Track Data] [Prepared by Gary Padgett] |
MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
SEPTEMBER, 2006
NOTE FROM THE AUTHOR: Almost two years ago I began including links to
track graphics prepared by John Diebolt of Tucson, Arizona, and archived
on his tropical cyclone website. A few months back John experienced a
disk crash which resulted in a error. He had to request assistance from
the programmer who had written the map-generation software, but so far
has not been able to get the problem solved. As a convenience to users,
I've also recently been including links to the individual tabular tracks,
prepared by myself, which John had archived on his website. Now, due to
family concerns, John has not had time to place the tracks for recent
cyclones on the website. I have checked the websites listed at the end
of the summaries and found that the entire September track file has been
archived on two of them. The links are:
http://australiasevereweather.com/cyclones/2007/trak0609.htm>
http://www.typhoon2000.ph/garyp_mgtcs/sep06tks.txt>
(For general comments about the nature of these summaries, as well as
information on how to download the tabular cyclone track files, see
the Author's Note at the end of this summary.)
*************************************************************************
SEPTEMBER HIGHLIGHTS
--> Atlantic more active--four hurricanes form but all recurve well out
in Atlantic--Bermuda, Newfoundland, Azores, Spain, Ireland and
Great Britain experience some effects
--> Major hurricane strikes mainland Mexico
--> Intense typhoon slashes through central Philippines while another
strikes Ryukyus
--> Strong Arabian Sea tropical storm forms just off western Indian
coast
*************************************************************************
!!!!!!!!!! EXTRA FEATURE !!!!!!!!!!
SOUTHERN HEMISPHERE TROPICAL CYCLONE NAMES
2006 - 2007 SEASON
TROPICAL CYCLONE NAMES for the AUSTRALIAN REGION
The Australian Bureau of Meteorology maintains three Tropical
Cyclone Warning Centres (TCWC): Perth, Western Australia; Darwin,
Northern Territory; and Brisbane, Queensland. Each centre is allotted
a separate list of tropical cyclone names for tropical cyclones forming
within its area of responsibility (AOR). In addition a TCWC located at
Port Moresby, Papua New Guinea (PNG)--a former Australian territory--
maintains a list of native names to assign to the very rare tropical
cyclones which form within its AOR.
The AORs of the respective centres are:
(1) Perth - 125E westward to 90E and south of 10S. Currently, and for
at least the next few years, the Perth TCWC will issue warnings for
any systems north of 10S and south and west of the Indonesian islands.
(2) Darwin - 125E eastward to 138E and extending northward to the
equator. There is a little irregularity with the eastern border
in the Gulf of Carpentaria. The Darwin TCWC issues High Seas
Warnings for the entire Gulf of Carpentaria, but Brisbane issues
Tropical Cyclone Advices and names cyclones in the eastern portion
of the Gulf. Also, currently, and for at least the next few years,
the Darwin TCWC will issue warnings for any systems west of 125E
and within the Indonesian archipelago in the Banda, Flores, and
Java Seas.
(3) Brisbane - 138E eastward to 160E and generally south of 10S. The
northern border with the Port Moresby AOR is somewhat irregular.
(4) Port Moresby, PNG - immediate vicinity of the island of New Guinea
and eastward to 160E generally north of 10S although the southern
border is somewhat irregular.
Names for the 2006-2007 season (** indicates name has already been
assigned):
Perth Darwin Brisbane Port Moresby
-----------------------------------------------------------------------
Isobel ** George Nelson Alu
Jacob Helen Odette Buri
Kara Ira Pierre Dodo
Lee Jasmine Rebecca Emau
Melanie Kim Sheryl Fere
Nicholas Laura Tania Guba
Ophelia Matt Vernon Hibu
Pancho Narelle Wendy Ila
Rosie Oswald Alfred Kama
Selwyn Penny Blanch Lobu
Tiffany Caleb
Victor Denise
Zelia Ernie
Alison Frances
Billy Greg
TROPICAL CYCLONE NAMES for the SOUTHWEST INDIAN OCEAN
and the SOUTH PACIFIC OCEAN
The Tropical Cyclone Warning Centre (TCWC) at Nadi, Fiji, has
tropical cyclone warning responsibility for the South Pacific east of
160E and from the equator to 25S. The Meteorological Service of New
Zealand at Wellington has warning responsibility for waters south of
25S, but almost all tropical cyclones in this basin form north of 25S.
When a rare cyclone forms in the Wellington area of responsibility
(AOR), it usually will be assigned a name from the Fiji list (such as
was done for Tropical Cyclone Gita in February, 1999.)
Tropical cyclone warning responsibility for South Indian waters west
of 90E are shared by several TCWCs. The Regional Specialty
Meteorological Centre (RSMC) for the region is the office of Meteo
France on the island of La Reunion. However, following a long-standing
practice, the Sub-regional Tropical Cyclone Advisory Centres at Mauritius
and Madagascar share the responsibility for actually naming tropical
storms with Mauritius naming systems east of 55E and Madagascar covering
the area west of 55E. RSMC La Reunion issues warnings for the basin
independently of Mauritius and Madagascar, but only advises regarding when
or when not to assign a name to a developing cyclone.
Names for the 2006-2007 season (** indicates name has already been
assigned):
Southwest Indian South Pacific
-----------------------------------------------------------------------
Anita ** Newa Xavier ** Hettie
Bondo ** Olipa Yani ** Innis
Clovis ** Panda Zita ** Joni
Dora Quincy Arthur ** Ken
Enok Rabeca Becky Lin
Favio Shyra Cliff Mick
Gamede Tsholo Daman Nisha
Humba Unokubi Elisa Oli
Indlada Vuyane Funa Pat
Jaya Warura Gene Rene
Katse Xylo
Lisebo Yone
Magoma Zouleha
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for September: 2 hurricanes
2 major hurricanes
Sources of Information
----------------------
Most of the information presented below was obtained from the
various tropical cyclone products issued by the Tropical Prediction
Center/National Hurricane Center (TPC/NHC) in Miami, Florida:
discussions, public advisories, forecast/advisories, tropical weather
outlooks, special tropical disturbance statements, etc. Some
additional information may have been gleaned from the monthly
summaries prepared by the hurricane specialists and available on
TPC/NHC's website. All references to sustained winds imply a
1-minute averaging period unless otherwise noted.
Atlantic Tropical Activity for September
----------------------------------------
Following are some statistics for the Atlantic basin during the month
of September:
September Average
Parameter 2006 1950 - 2005
--------------------------------------------------------
Named Storms (NS) 4 3.5
Hurricanes (H) 4 2.5
Intense Hurricanes (IH) 2 1.3
Named Storm Days (NSD) 30.75 23.0
Hurricane Days (HD) 18.25 12.9
Intense Hurricane Days (IHD) 3.00 3.4
The month of September, 2006, was above average in all but the IHD
parameter, and that was near normal. The overall net tropical cyclone
activity (utilizing all six parameters) was about 132% of the average
level normally seen in September, whereas in August overall tropical
cyclone activity was only about half of normal. The month was only
slightly less active than September, 2005, whose overall tropical
cyclone activity level was about 147% of the average. The Northeast
Pacific basin, which had been extremely active in August, was well
below normal in September.
As the month opened, Tropical Storm Ernesto was approaching the coast
of North Carolina just shy of hurricane intensity. Ernesto made land-
fall in North Carolina early in the morning of 1 September and continued
northward through the Mid-Atlantic states as it weakened over the next
couple of days. The complete report on Hurricane Ernesto may be found
in the August summary.
Four hurricanes formed in the tropical Atlantic during the month of
September, and all recurved northeastward well east of the United States.
Hurricane Florence came the farthest west, passing just west of Bermuda
near its peak intensity of 80 kts. Florence then headed toward the
island of Newfoundland, and though it became extratropical, remained at
hurricane intensity and passed just southeast of the island. Hurricanes
Gordon and Helene both became Category 3 hurricanes but passed northward
several hundred miles east of Bermuda. Helene did not affect any land
areas, but Gordon accomplished the rare feat of passing through the
Azores Islands as a hurricane, although none of the islands experienced
sustained hurricane-force winds. However, the hurricane's extratropical
stage brought very strong winds to the Iberian Peninsula and the British
Isles, causing widespread damage. Finally, at the end of the month
Hurricane Isaac recurved a few hundred miles east of Bermuda and later
brushed Newfoundland's Avalon Peninsula while still a strong tropical
storm.
Reports on all the September hurricanes follow. The link to the
Wikipedia page for the 2006 Atlantic hurricane season is as follows:
http://en.wikipedia.org/wiki/2006_Atlantic_hurricane_season>
Detailed reports for Florence and Gordon are available and the links to
those appear in their respective summaries below. However, no detailed
Wikipedia reports are available for Helene and Isaac, but brief reports
with a satellite image and track chart may be found at the above link.
HURRICANE FLORENCE
(TC-06)
3 - 15 September
--------------------------------------
A. Introduction and Storm Origins
---------------------------------
Hurricane Florence was the first Cape Verde hurricane of the 2006
Atlantic tropical cyclone season. The storm was notable in its early
tropical storm stage for its extremely large size. At one point on
8 September gales covered an area 600 nm in diameter--with the MSW at
only 45 kts. Florence eventually consolidated its forces some as it
reached hurricane intensity, but still remained a rather large tropical
cyclone. The storm passed just west of Bermuda on 11 September, later
transforming into a severe extratropical cyclone and bringing winds of
hurricane force to southeastern Newfoundland. Florence was the only
one of the four September hurricanes to pass west of Bermuda--the
remaining three recurved well east of the British colony.
A tropical wave moved off the African coast during the final week of
August and by late on the 28th was located about 525 nm southwest of
the Cape Verde Islands. By the 29th the wave was producing a
concentrated area of convection which was showing some signs of
organization. However, by the next day the shower activity had become
disorganized and no imminent development was anticipated. By the after-
noon of the 31st organization had improved once more and slow development
was considered possible as the system moved slowly westward.
The morning of 1 September found the wave located about 750 nm west-
southwest of the Cape Verdes with little change in organization. Shower
activity increased once more on 2 September with the system now located
about 1050 nm east of the Windward Islands. A second area of disturbed
weather was located to the east and the presence of this disturbance
was thought to be having a slight inhibiting effect on the westernmost
system. The wave located to the east had emerged from the African coast
on 29 August and by 2 September was showing distinct signs of increased
organization. By 3 September it was becoming apparent that the eastern-
most wave was developing, and the first wave, located then only about
350 nm to the west, was forecast to weaken and merge with the second
wave.
Advisories were initiated on Tropical Depression 06 at 2100 UTC on
3 September with the center located approximately 1325 nm east of the
Leeward Islands and moving northwestward at 12 kts. SAB and TAFB were
assigning Dvorak classifications of T2.0, and buoy 41026 had reported
32-kt winds late in the morning, so the initial intensity was estimated
at 30 kts. The circulation was broad and the center was difficult to
pinpoint, and also it was considered likely that multiple swirls were
rotating around a common center. The depression continued moving slowly
west-northwestward over the next couple of days. Banding features were
impressive, but the LLCC was broad with several possible centers. An
upper-level trough to the northwest was inducing some southwesterly
shear over the cyclone, and in conjunction with some drier air,
development proceeded rather slowly.
B. Synoptic History
-------------------
The depression was upgraded to Tropical Storm Florence at 1500 UTC
on 5 September, nearly two days after being classified as TD-06. The
upgrade was based primarily on QuikScat and SSM/I data which showed
large patches of 30-35 kt uncontaminated winds in the northwest quadrant.
Florence at this time was located around 800 nm east of the Leeward
Islands and was moving westward at 10 kts. Gales extended out over
100 nm in the northeast quadrant and 90 nm to the northwest. Once
named, the large, sloppily-organized tropical storm intensified very
slowly. Winds were upped to 40 kts at 05/1800 UTC and to 45 kts at
06/1500 UTC, but remained pegged there for almost three days as Florence
continued on a west-northwesterly track. The cloud pattern was at times
shapeless with very asymmetric convection, and locating the LLCC was a
continuing difficult job. Due to the large size of the storm and given
the forecast track, the Bermuda Weather Service issued a hurricane watch
for the island at 2100 UTC on 8 September with the center located 550 nm
to the south-southeast.
Florence began to display some signs of strengthening on the 8th. An
Air Force hurricane hunter aircraft reached the storm around 0400 UTC
on 9 September and found a CP of 993 mb with a maximum 850-mb FLW of
61 kts about 50 nm northeast of the center, so the MSW was upped to
55 kts at 09/0600 UTC. Satellite intensity estimates had increased to
65 kts from SAB and AFWA and 55 kts from TAFB. However, it was to be
24 hours longer before Florence finally became the season's second
hurricane. During the 9th satellite intensity estimates continued to
rise, but other considerations led to Florence being held at tropical
storm intensity, and later in the day the storm exhibited a slight
weakening trend. The MSW was upped to 60 kts at 1800 UTC, but decreased
slightly to 55 kts three hours later.
Florence was finally upgraded to hurricane status at 0600 UTC on
10 September while located about 315 nm south of Bermuda and moving
north-northwestward at 11 kts. A reconnaissance aircraft had found
peak FLWs of 84 kts and a CP of 976 mb with a pressure drop of 17 mb
in a 12-hour period. Florence continued to strengthen, reaching its
peak intensity of 80 kts at 1800 UTC on the 10th while centered about
200 nm south-southwest of Bermuda. This was based on a peak FLW of
96 kts measured by a reconnaissance plane, but using a slightly lower
reduction factor than the normal 90% used for reducing 700-mb FLWs to
the surface. Dropsonde data suggested that a reduction factor of 80
to 85% would be more appropriate in this case. Florence turned north-
ward on the 11th and made its closest approach to Bermuda around
11/1200 UTC, the center passing about 50 nm to the west of the colony.
The estimated MSW had dropped briefly to 70 kts, but was upped back
to 80 kts three hours later. An elevated observing site in Bermuda
reported a peak wind gust of 97 kts. Hurricane force winds extended
outward 60 nm from the center in the eastern quadrants and 30 nm to
the west. Florence's estimated minimum CP of 972 mb occurred around
11/1800 UTC.
The hurricane had shifted to a north-northeastward heading as it was
brushing by Bermuda, and the track became increasingly northeasterly as
Florence accelerated into the North Atlantic ahead of a mid-level
tropospheric trough over the Canadian Maritimes. The storm also began
to weaken significantly on the 12th and winds had dropped to minimal
hurricane intensity by 0600 UTC. Satellite imagery indicated that
Florence was in the early to mid stages of extratropical transition.
Dry middle and upper-level air wrapping around the southern periphery
had eroded most of the inner-core deep convection. TPC/NHC issued
their final advisory on Florence at 12/2100 UTC with the center located
about 525 nm southwest of Cape Race, Newfoundland, moving northeastward
at 18 kts. The only convection remaining near the center was a band
of showers and thunderstorms located about 100 nm northwest of the
center.
Florence transformed into a powerful extratropical cyclone of
hurricane intensity and actually strengthened to 70 kts while near south-
eastern Newfoundland. This re-intensification was due to interaction
with the upper-level trough located over the Maritimes. The center of
post-tropical Florence passed just south of Cape Race with a CP
estimated around 963 mb. Sustained hurricane-force winds were
recorded on Sagona Island in Fortune Bay with gusts well above hurricane
intensity felt on the Burin Peninsula and along the Newfoundland coast
from Fortune Bay to Burgeo, including St. Pierre and Miquelon. After
passing by Newfoundland the remnants of Florence accelerated eastward
across the North Atlantic, slowly weakening. By 1800 UTC on 15 September
the former hurricane had weakened into a 35-kt gale roughly halfway
between Newfoundland and Ireland. The ex-Florence LOW was eventually
forced northward toward Iceland while a weak front associated with the
storm's remnants made its way toward Great Britain.
C. Meteorological Observations
------------------------------
As noted above, an elevated site in Bermuda (elevation unknown)
reported a peak wind gust of 97 kts.
In Newfoundland, the following peak wind gusts and storm total
rainfalls were reported (data courtesy of Chris Fogarty--thanks to
Chris for sending it along):
Sagona Island 88 kts
St. Lawrence 72 kts 47 mm
St. Pierre 69 kts
Bonavista 59 kts 33 mm
Cape Race 58 kts 25 mm
Grates Cove 58 kts
Pool's Island 58 kts
St. John's 55 kts 48 mm **
Twillingate 54 kts 22 mm
Burgeo 53 kts 14 mm
Argentia 49 kts 35 mm
Gander 42 kts 56 mm
Terra Nova Park 58 mm
Cape Pine * 41 mm
* - private weather station on the southern Avalon Peninsula
** - 48 mm fell at St. John's airport and 52 mm in Mount Pearl
D. Damage and Casualties
------------------------
In Bermuda strong winds blew down trees and power lines, leaving over
25,000 homes and businesses without power at the height of the storm.
A few houses experienced window and roof damage, and a few injuries
were reported. Overall damage, however, was relatively light.
During the course of its life Florence produced strong swells and
dangerous surf conditions, including rip currents, in the northern Lesser
Antilles, Virgin Islands, Puerto Rico, Hispaniola, Bahamas, along the
U. S. Eastern Seaboard, and in the Canadian Maritimes. However, no
fatalities are known to have resulted from Hurricane Florence.
In Newfoundland some damage was reported in the form of blown down
trees and damage to shingles and siding of homes. Also, some boats
and roadways were damaged in and around the Burin Peninsula from heavy
surf conditions. Power outages were also reported in the St. John's
area.
More information can be found in the online Wikipedia report, from
which some of the above information was obtained. The link is:
http://en.wikipedia.org/wiki/Hurricane_Florence_%282006%29>
(Report written by Gary Padgett)
HURRICANE GORDON
(TC-07)
11 - 21 September
-------------------------------------
A. Introduction and Storm Origins
---------------------------------
Hurricane Gordon became the first intense hurricane of the 2006
Atlantic hurricane season, reaching Category 3 status on the Saffir/
Simpson scale on 13 September while several hundred miles southeast
of Bermuda. While an impressive Category 3 hurricane, the most
remarkable aspect of Gordon's life was a re-intensification to
Category 2 status near latitude 40N after weakening to a minimal
hurricane three days earlier. Also unusual was the storm's passage
through the central Azores while still a tropical cyclone of hurricane
intensity. Finally, in its extratropical stages the cyclone brought
very strong winds to Spain, the United Kingdom and Ireland.
A tropical wave left the coast of Africa on 1 September and began
marching westward across the tropical Atlantic. By the morning of
4 September the system was located several hundred miles west of the
Cape Verde Islands and was showing signs of organization. The system
looked even better the next day, but by the 6th environmental conditions
had become less favorable. The primary inhibiting factor was the
proximity of the disturbance to large Tropical Storm Florence. The
system continued to move west-northwestward for the next few days and
managed to produce disorganized showers and thunderstorms. As the
separation between this system and Florence slowly increased, conditions
gradually improved and by the afternoon of 10 September thunderstorm
activity had become more concentrated near the circulation center about
475 nm east-northeast of the Leeward Islands.
The first advisory was issued on Tropical Depression 07 at 0300 UTC
on 11 September, the center being located about 455 nm east-northeast
of the Leeward Islands and moving westward at 5 kts. The initial MSW
was set to 25 kts, based on 0000 UTC Dvorak estimates of T1.5 and a
report of WSW 27-kt winds from ship MSJX8 just south of the center.
In contrast to Florence, which was a huge tropical cyclone in area,
TD-07 was a small cyclone with the entire circulation about 300 nm
wide and with deep convection mostly confined to the southern semicircle.
The depression gradually turned to a northwesterly track as its
organization slowly improved. A reconnaissance mission into the system
around midday on the 11th found peak FLWs of 47 kts, corresponding to
38 kts at the surface. Based on this the depression was upgraded to
Tropical Storm Gordon at 11/2100 UTC with the intensity estimated at
40 kts. Gordon was then located about 375 nm northeast of the Leewards,
moving to the northwest at 8 kts. The storm was quite small: gales
extended outward 40 nm from the center to the northeast and 25 nm to
the southeast with no gale-force winds found in the western quadrants.
B. Synoptic History
-------------------
The strengthening Gordon soon turned northward toward a break in
the subtropical ridge left in the wake of Florence. And even though
the earlier storm was moving out of the way, an upper-level LOW
located about 1000 nm to the east-northeast of Gordon was forecast
by the global models to move westward and break down the remaining
subtropical ridge, allowing the storm to recurve. Gordon was upgraded
to a hurricane at 0300 UTC on 13 September while located almost 500 nm
north-northeast of the Leeward Islands and moving north at 8 kts. The
upgrade was based on the appearance of an intermittent eye feature and
Dvorak T-numbers of 4.0 and 4.5 from all agencies. By 1500 UTC Gordon
had developed a well-defined eye and the MSW was increased to 80 kts.
Although not yet forecast to become a major hurricane, Gordon's
satellite signature continued to improve and at 14/0300 UTC the cyclone
was upgraded to a Category 3 hurricane with winds of 105 kts and an
estimated CP of 955 mb, which proved to be Gordon's peak lifetime
intensity. Subjective T-numbers had reached 5.5 while the AODT had
been giving 3-hour estimates of T6.0. Gordon had become embedded in
mid-latitude westerly flow and was moving north-northeastward at 11 kts
from a position about 485 nm east-southeast of Bermuda. Hurricane-force
winds were confined to a zone within about 25 nm of the center while
gales reached outward over 100 nm in all quadrants.
Gordon held on to its 105-kt peak for about 24 hours, then slowly
began to weaken as it began to move over gradually cooling waters. By
the 15th the low-level ridge to the east of Gordon had weakened and the
hurricane was left in an area with very weak steering currents.
Consequently, Gordon remained quasi-stationary for over 24 hours as
mid-level ridging to the north and east of the hurricane strengthened.
The MSW had dropped to 65 kts by 0900 UTC on 16 September, and continued
weakening with extratropical transition within 72 hours was forecast.
Gordon, however, had other plans. The storm continued to display a
ragged eye in infrared imagery for the next day and maintained hurricane
intensity. At 1500 UTC on the 17th satellite imagery depicted an eye,
deep convection and impressive outflow. TAFB and SAB were both reporting
Dvorak estimates of 77 kts with AFWA's being 65 kts, so the MSW was upped
to 70 kts. The storm by this time was moving north-northeastward at
9 kts and the track became increasingly eastward at a faster pace as the
day wore on.
Gordon's winds were upped further to 80 kts at 1500 UTC on the 18th.
The storm was located almost 1000 nm west of the Azores, moving north-
eastward at 17 kts, and all the models were anticipating a due eastward
track as the hurricane was steered by the zonal westerlies north of the
subtropical ridge. At 18/2100 UTC a tropical storm watch was issued
for the Azores as the official forecast carried the storm over or very
near the islands during the next 24 to 36 hours. Hurricane Gordon
reached a secondary peak intensity of 90 kts at 19/0900 UTC while
located about 550 nm west of the island of Terceira in the Azores,
scooting eastward at 24 kts. The eye was remaining distinct and cloud-
free and intensity estimates ranged from 77 to 90 kts. Gordon was
a healthy Category 2 hurricane bearing down on the Azores--something
not seen very often.
As the cyclone approached the Azores it began to slowly weaken but
was still sporting 75-kt winds as it moved rapidly through the central
part of the island chain. At 20/0000 UTC Gordon was located about
210 nm west of Sao Miguel, moving eastward at 29 kts. Six hours later
the center was 75 nm south-southeast of Terceira and the MSW had dropped
to 65 kts. AMSR-E microwave data indicated that the westerlies had
finally begun to affect the vertical structure of Gordon with the
center displaced about 60 nm west of the limited deep convection. The
cyclone was downgraded to a 50-kt tropical storm at 20/1200 UTC but still
had the tropical characteristics of a warm core and deep convection near
the center. However, a strong cold front was approaching the core and
extratropical transition was just around the corner. TPC/NHC issued its
final advisory on Gordon at 20/2100 UTC since the cold front had
interacted with the cyclone's circulation. The storm's center was then
located about 340 nm west of Lisbon, Portugal, racing eastward at 30 kts.
Following extratropical transition, the storm tracked northwestward
toward the Iberian Peninsula, turning northward on 21 September towards
Great Britain and Ireland. By the 22nd it had become completely
absorbed into a large LOW to the west of Ireland.
C. Meteorological Observations
------------------------------
As Gordon sped through the Azores, a 10-min avg sustained wind of
49 kts with a peak gust of 71 kts was reported at Santa Maria airport
in the eastern Azores.
In Spain, as the extratropical stage of Gordon paid a visit to the
Iberian Peninsula, gusts up to 89 kts were reported at Fisterra. Also,
Castro Vicaludo-Oia reported gusts to 91 kts. Some other peak wind
gust reports: Cabo Vilan - 82 kts; Ferrol - 64 kts; Alvedro - 60 kts;
Ancares - 55 kts; Oiz - 59 kts. Near Madrid winds to 57 kts were felt
at Punto Navacerrada. Heavy rains fell across Spain with 65.5 mm
recorded at Canfranc. A pressure of 989.7 hPa was measured at Coruna
(unknown if this was adjusted to MSL). Also, waves up to 7 meters were
reported.
In the UK, a gust of 70 kts was recorded in southwest Great Britain
late on the 21st. Also, gusts to 65 kts affected Northern Ireland
during the night of 21-22 September. High winds were also felt in
Scotland and Ireland from the extratropical remnants of Gordon.
D. Damage and Casualties
------------------------
In the Azores damage was relatively light with only reports of toppled
trees and power lines. A few communities lost electrical power,
particularly on Santa Maria Island.
The strong winds experienced over much of Spain blew down trees,
traffic lights and signs. One man was injured due to a tree falling
on his car, and many roads were blocked by fallen trees. Another
report indicated that four people were injured in the Galicia region
with 100,000 homes losing power. Portugal also experienced heavy rain
and wind gusts that downed trees and caused roof damage.
In Ireland around 1500 homes lost power due to the stormy conditions
wrought by ex-Gordon, and there was one injury reported. In southwestern
England more than 1000 homes lost power in Truro, Cornwall, and a rail
line between Exeter and Plymouth was damaged by high surf. Up to
100,000 homes in Northern Ireland lost power as tree branches fell on
power lines, and fallen trees blocked many roads with flooding reported
in some areas.
Additional information can be found in the online Wikipedia report
from which some of the above information was obtained. The link is:
http://en.wikipedia.org/wiki/Hurricane_Gordon_%282006%29>
(Report written by Gary Padgett)
HURRICANE HELENE
(TC-08)
12 - 26 September
-------------------------------------
A. Introduction and Storm Origins
---------------------------------
Hurricane Helene, the fourth hurricane of the 2006 Atlantic season,
was a classic Cape Verde hurricane in every sense of the word, forming
as a tropical depression south of the islands and becoming a large,
intense hurricane. Fortunately, unlike many Cape Verde hurricanes of
the past, Helene recurved well to the east of Bermuda and did not
threaten any populated areas in the western Atlantic basin. Also, the
storm was the only one of the September hurricanes which did not affect
Newfoundland or the Azores, passing well between those islands. In some
aspects the hurricane was similar to its namesake in 1988. However, the
Hurricane Helene of that year was somewhat more intense, becoming a
Category 4 hurricane as it moved northward through the central Atlantic.
This year's Helene became the strongest hurricane of the season, peaking
at 110 kts on 18 September--a strong Category 3 hurricane on the Saffir/
Simpson scale (although there is some possibility this value was a
little too high--see discussion below).
A strong tropical wave emerged from the western coast of Africa on
11 September and immediately began to show signs of developing as a
tropical cyclone. By the morning of the 12th the system had become
sufficiently organized that advisories were initiated on Tropical
Depression 08, located about 160 nm south-southeast of the southernmost
Cape Verde Islands and moving west at 16 kts. A well-defined curved
convective band had formed over the western semicircle and two ship
reports of northerly and southerly winds confirmed the existence of
a closed surface circulation. Although it was anticipated that TD-08
would become a tropical storm by early on the 13th, intensification
proceeded somewhat more slowly than forecast. The depression was large
and somewhat elongated with multiple low-level swirls within a larger
circulation gyre. By the evening of 13 September the depression's
convective pattern had gradually become better organized and Dvorak
T-numbers had reached 2.5 from all agencies; hence, the system was
upgraded to Tropical Storm Helene at 14/0300 UTC. Helene was located
about 490 nm west of the Cape Verdes and moving quickly to the west-
northwest at 19 kts along the southern periphery of a deep-layer ridge.
B. Synoptic History
-------------------
After reaching tropical storm intensity, Helene was slow to intensify
further. Winds remained at 40 kts through 15/0900 UTC, but were bumped
up to 50 kts at 1500 UTC after satellite imagery revealed that the cloud
pattern had become better organized. With low shear and warm SSTs ahead
along the anticipated track, Helene was forecast to reach hurricane
intensity within 24 hours. The cyclone was upgraded to the season's
fourth hurricane at 16/1500 UTC while centered approximately 1000 nm
east of the northern Leeward Islands. Once having reached that milestone
Helene began to steadily intensify as it continued to churn northwestward
along the southwestern side of the deep-layer ridge toward a weakness in
the ridge. Helene became the season's second major hurricane at 18/0300
UTC when winds were upped to 100 kts, and the storm reached its peak
estimated intensity of 110 kts at 1500 UTC while centered about 950 nm
east-southeast of Bermuda, moving northwestward at 8 kts. Earlier that
morning Helene had reached the longitude of Gordon and the storm had
temporarily moved on a north-northwestward track for several hours, but
by advisory time it appeared that an anticipated westward turn, forecast
by the global models, was about to begin.
A surprise was in store later that afternoon. A NOAA research
aircraft made a pass through the center of Helene and found that the
hurricane was not quite as strong as previously estimated by satellite.
Based on the reconnaissance findings, the MSW was lowered to 100 kts at
2100 UTC. (It seems very possible to the author that in post-storm
analysis Helene's peak MSW may be lowered to 105 or even 100 kts.) On
the 19th Helene's motion became westerly as a mid-tropospheric ridge to
the north built, but by the 20th the storm was moving northwestward once
more. A NOAA aircraft made a pass through Helene early on the afternoon
of the 19th and measured a CP of 956 mb. The peak FLW was 98 kts at
850 mb in the northwest quadrant, and two eyewalls were present at radii
of 40 nm and 120 nm. Based on these findings Helene's MSW was reduced
to 95 kts. This brought the hurricane down to Category 2 status, and
even though brief re-intensification to a Category 3 hurricane was
forecast, this never materialized. Helene at this stage was a fairly
large hurricane with hurricane-force winds extending outward 55 nm to
the northeast of the center and 35 nm to the southwest. Gales covered
a zone over 300 nm in diameter.
Over the next few days Helene continued to weaken very slowly as it
moved over gradually cooling SSTs and encountered some drier air. The
storm's heading gradually turned to the north and then northeastward
ahead of an approaching trough in the westerlies. The MSW was reduced
to 85 kts at 21/0300 UTC based upon data from a NOAA P-3 mission during
the previous afternoon--satellite intensity estimates at the time ranged
from 77 to 90 kts. The storm passed about 485 nm east of Bermuda around
0900 UTC on 22 September, moving northeastward at 13 kts. The intensity
was lowered to 70 kts at 21/1500 UTC but was bumped back to 75 kts twelve
hours later as cold cloud tops had expanded and become more concentric
around the center. However, the satellite presentation soon began to
deteriorate once again and Helene was reduced to minimal hurricane
intensity at 22/2100 UTC and downgraded to a 60-kt tropical storm six
hours later. A QuikScat pass from around 2200 UTC showed 50-60 kt
winds southeast of the center.
In a manner somewhat similar to Hurricane Gordon, Helene pulled a
surprise over the reaches of the North Atlantic. The TPC/NHC discussion
at 23/0900 UTC noted that a small burst of convection with cloud tops
to -60 C had persisted over the LLCC for more than six hours, and given
the forward speed of 22 kts, the intensity could be higher than the
advisory MSW of 60 kts. At 23/1200 UTC a special advisory was issued,
upping the winds to 80 kts. A recent QuikScat pass had indicated that
Helene possessed a large area of hurricane force winds southwest of the
center and the data showed some vectors to 80 kts. So Helene was
re-upgraded to a hurricane, even though the storm appeared to be in
the process of transforming into an extratropical cyclone. The 2100 UTC
discussion noted that the cyclone displayed both tropical and extra-
tropical characteristics. Helene had a frontal-like and asymmetric
appearance in satellite imagery with limited deep convection, yet FSU
cyclone phase space diagrams diagnosed the storm with a deep-layer warm
core.
The MSW remained 80 kts for the 2100 UTC advisory but began to decline
after that. The final TPC/NHC advisory on Helene was issued at 1500 UTC
on 24 September, placing the center about 515 nm west-northwest of the
Azores and moving northeastward at 19 kts. The previous advisory had
treated Helene as a 75-kt hurricane, but the final one reduced the system
to a 60-kt extratropical storm. Helene by this time had acquired
definitive frontal features with extensive cold-air advection over the
southwestern semicircle. Also, a QuikScat pass around 0900 UTC had
suggested that the strongest winds were becoming removed from the center.
Interestingly, microwave data still showed a warm core, but this was
believed to be due to a warm seclusion that is common in strong extra-
tropical cyclones. The post-tropical Helene continued to speed east-
northeastward across the North Atlantic and by 25/0000 UTC was generating
hurricane-force winds of 70 kts around a 964-mb center. Thereafter, the
system began to slowly weaken and the last information available to the
author placed a 980-mb center well north of the Azores at 26/0000 UTC.
C. Damage and Casualties
------------------------
No casualties or damage are known to have resulted from Hurricane
Helene.
(Report written by Gary Padgett)
HURRICANE ISAAC
(TC-09)
27 September - 4 October
--------------------------------------------
A. Introduction and Storm Origins
---------------------------------
Hurricane Isaac, the final hurricane of September and (as of this
writing--9 November) the final tropical cyclone of the 2006 Atlantic
season, followed a similar trajectory to its two predecessors, Gordon
and Helene, recurving well east of Bermuda. Isaac, however, didn't
recurve quickly enough to miss Newfoundland, and the storm brushed the
extreme southeastern tip of the island while still a fairly strong
tropical storm shortly before becoming extratropical. If indeed there
are no more tropical cyclones this season, 2006 will be the first
season since 1963 to produce exactly 9 tropical storms or hurricanes
(although in that season one tropical storm was unnamed). The last
year to see exactly 9 named storms (down through the letter "I") was
1964. However, during post-analysis 3 unnamed storms were added to
the official roster, making a total of 12 tropical storms/hurricanes.
(These statistics are based upon the current Best Track database. When
the ongoing reanalysis is complete these records may no longer hold.)
Isaac's origins can be traced back to a tropical wave which emerged
from the African coast on 18 September. By early morning of the 20th
the wave was accompanied by a broad surface LOW centered about 390 nm
south-southwest of the southernmost Cape Verde Islands. Convective
activity had increased and additional development was anticipated over
the next couple of days as the system moved west-northwestward. As
things turned out, a week elapsed before the system was upgraded to
a tropical depression. On the 23rd convective activity became better
organized, but by the next day upper-level winds had strengthened and
the potential for a tropical depression to form had diminished. During
the evening of 25 September the wave was looking a little healthier once
more and this trend continued through the 26th and into the 27th.
Environmental conditions gradually became more conducive for tropical
cyclogenesis and the first advisory on Tropical Depression 09 was issued
at 2100 UTC on 27 September. Visible satellite pictures indicated
that the LLCC had gradually become better defined and there was
sufficient deep convection for the system to be classified as a 30-kt
tropical depression. The center of TD-07 was located about 705 nm east-
southeast of Bermuda and moving northwestward at 12 kts. The depression
was upgraded to Tropical Storm Isaac at 1500 UTC the next morning (28th),
located about 575 nm east-southeast of Bermuda and moving northwestward
at 7 kts. The upgrade was based primarily on data from a QuikScat pass
at 0845 UTC which had shown evidence of 35-kt winds in the system.
Isaac was exhibiting some characteristics of a subtropical storm with
the radius of maximum winds near 75 nm and with an upper-level LOW almost
on top of the system. Some modest intensification was forecast. Even
though SSTs in Isaac's forecast track were near 26 C, upper-level
temperatures were also colder than normal, which would allow for more
instability and more convection.
B. Synoptic History
-------------------
The subtropical-like features continued on into 29 September.
Convection was becoming more consolidated around the center, but the
convection was rather weak with only a few cloud tops colder than -50 C.
By afternoon of the 29th Isaac was showing definite signs of increasing
strength: convection was increasing and attempting to form a ring
around the center and outflow was expanding and becoming more symmetric.
One factor which had earlier had some inhibiting effect on Isaac's
intensification was that it had been moving over cooler waters upwelled
by Gordon and Helene. The tropical cyclone was now leaving these cooler
waters behind and moving into a region with warmer SSTs and low vertical
shear. The 29/2100 UTC advisory was the first to forecast that Isaac
would reach hurricane intensity.
Isaac was upgraded to a hurricane at 1500 UTC on 30 September while
centered about 325 nm east-southeast of Bermuda. The cyclone was still
moving on a rather slow northwesterly track at 6 kts. Isaac had formed
a ragged eye, and a high-resolution QuikScat pass at 1000 UTC showed one
believable wind vector of 63 kts. Since that time, the storm's satellite
signature had improved and TAFB was reporting a T-number of 4.0. By
0600 UTC on 1 October Dvorak ratings from TAFB and SAB had reached T4.5,
so Isaac's MSW was bumped up to 75 kts--the peak for the storm's history.
Hurricane Isaac was then located about 245 nm east-northeast of Bermuda,
moving north-northwestward at 8 kts. The cyclone was situated between
the southwestern flank of a rather small deep-layered subtropical ridge
and a very large trough along the U. S. Atlantic Seaboard. A northward
turn was forecast, followed by acceleration to the northeast.
Following its peak in intensity Isaac's MSW slowly began to decrease.
Twenty-four hours after peaking in intensity Isaac had weakened into a
minimal 65-kt hurricane. Microwave imagery revealed that the LLCC was
displaced about 30 nm southwest of the mid-level center, and Dvorak
ratings from TAFB and SAB had decreased to T4.0 and T3.5, respectively.
The storm had recurved and was moving north-northeastward at 26 kts.
Isaac was downgraded to a 50-kt tropical storm at 02/1500 UTC, centered
about 165 nm south-southwest of Cape Race, Newfoundland, racing north-
northeastward at 36 kts. The cyclone passed just south of Cape Race
during the afternoon of 2 October, and by 2100 UTC Isaac was beginning
to take on extratropical features to the point that TPC/NHC issued their
final advisory on the system, which was then located about 45 nm east-
northeast of Cape Race. The extratropical remnants of Isaac continued
to speed northeastward across the North Atlantic, gradually turning east-
northeastward, and by 04/1800 UTC had weakened below gale force several
hundred miles west of Ireland.
C. Meteorological Observations
------------------------------
The only land area affected by Isaac was the island of Newfoundland.
Following is a summary of Isaac's impact in the area sent by Chris
Fogarty of the Canadian Hurricane Centre. A special thanks to Chris
for sending this write-up.
"The centre of Tropical Storm Isaac passed approximately 45 km south-
east of Cape Race, Newfoundland, late in the afternoon of October 2nd.
Isaac was moving very quickly to the northeast near 70 km/hr. The storm
circulation was very small and strong winds were confined to only a short
distance to the north of the centre. The storm had maximum sustained
winds of 50 knots (92 km/hr) and a central sea level pressure near 993 mb
at its closest approach to the Avalon Peninsula. Rain from Isaac quickly
spread across the Avalon but did not extend beyond Trinity and Placentia
Bays. Isaac was still in its tropical cyclone phase when it passed by
the Avalon as seen in radar imagery. There was a rain-free area near the
centre, perhaps indicating the remnants of the storm's eye.
"The strongest winds on land were reported at Cape Race where gusts
reached 96 km/hr (52 knots) with the highest sustained winds of 74 km/hr
(40 knots). A peak wind of 76 km/hr (41 knots) was reported at a private
weather station on Cape Pine about 30 km west of Cape Race. Because of
the compact circulation of the storm and its rapid forward motion, winds
were much lighter over most of the Avalon Peninsula. The highest wind
gust at St. John's International Airport was 54 km/hr (29 knots). Peak
winds from an offshore buoy south of the storm reached 56 knots or
104 km/hr.
"Rainfall amounts directly associated with Isaac were generally less
than 25 mm due to its rapid forward motion and diminishing amount of
moisture. The highest measured rainfall was 26 mm at Cape Race. 19 mm
was measured at the Cape Pine location and only 10 mm in the St. John's
area.
"Forecasting the track and speed of the storm was very challenging,
as are most tropical storms and hurricanes moving into our region. Given
that Isaac was still a strong tropical storm very near the Avalon
Peninsula, a tropical storm warning was issued for the potential for high
winds. If the storm had tracked only 50 to 100 km farther north, the
St. John's area would have experienced much stronger winds. Isaac also
moved faster than originally expected, thus rainfall amounts were less
than forecast."
D. Damage and Casualties
------------------------
No casualties or significant damage are known to have resulted from
Hurricane Isaac.
(Report written by Gary Padgett and Chris Fogarty)
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for September: 2 tropical depressions **
1 tropical storm
1 major hurricane
** - both the non-developing tropical depressions formed in the Central
North Pacific region
Sources of Information
----------------------
Most of the information presented below was obtained from the
various tropical cyclone products issued by the Tropical Prediction
Center/National Hurricane Center (TPC/NHC) in Miami, Florida (or the
Central Pacific Hurricane Center (CPHC) in Honolulu, Hawaii, for
locations west of longitude 140W): discussions, public advisories,
forecast/advisories, tropical weather outlooks, special tropical
disturbance statements, etc. Some additional information may have
been gleaned from the monthly summaries prepared by the hurricane
specialists and available on TPC/NHC's website. All references to
sustained winds imply a 1-minute averaging period unless otherwise
noted.
Northeast Pacific Tropical Activity for September
-------------------------------------------------
Following are some statistics for the Northeast Pacific basin during
the month of September:
September Average
Parameter 2006 1971 - 2005
--------------------------------------------------------
Named Storms (NS) 2 3.5
Hurricanes (H) 1 2.2
Intense Hurricanes (IH) 1 1.1
Named Storm Days (NSD) 11.25 17.4
Hurricane Days (HD) 3.75 8.3
Intense Hurricane Days (IHD) 0.75 2.6
The month of September, 2006, was well below normal in the Northeast
Pacific basin with the overall net tropical cyclone activity (utilizing
all six parameters) being only about 55% of the average level normally
seen in September, whereas in August the overall tropical activity had
been almost 2.5 times the average. The month also was much quieter than
September, 2005, when the overall net activity had been almost twice
the average. Interestingly, the Atlantic basin was quiet during August
when the Northeast Pacific was active, but was well above normal during
September when the Pacific was well below normal.
Two named storms developed, Hurricane Lane and Tropical Storm Miriam.
Lane was a small but intense hurricane which formed and remained near
the Mexican coast and ultimately made landfall near El Dorado as a strong
Category 3 hurricane--the first major hurricane to strike the West Coast
of Mexico in four years. Miriam was a short-lived minimal tropical storm
which formed in an extension of the ITCZ to the west of Lane and never
affected land. Reports on both Lane and Miriam follow below.
No more tropical cyclones formed east of 140W, but two tropical
depressions were classified by the Central Pacific Hurricane Center in
Honolulu during the month of September. Tropical Depression 02C formed
on the 18th about 675 nm south of Honolulu. This system was initially
forecast to reach hurricane intensity within 48 hours, but this forecast
failed miserably. TD-02C's winds reached 30 kts at 19/0600 UTC and this
was the highest for the depression�s history. The system was never able
to completely break away from the ITCZ and unable to develop persistent
rainbands and central convection. By 20/1200 UTC the low-level center
had become completely exposed with disorganized convection off to the
west of the center. Interestingly, some of the models were still
indicating that TD-02C would strengthen, but given the observed weakening
trend and the appearance, the intensity was lowered to 25 kts at 1500
UTC. The depression continued to weaken as it drifted westward and the
final CPHC advisory, issued at 20/2100 UTC, placed the dissipating center
about 395 nm southeast of Johnston Island. The remnants of TC-02C
continued to move westward and eventually brought some heavy rainfall
to Kwajalein Atoll. Some information on this will be included in Part 3
of the September summary, covering the Northwest Pacific basin.
Tropical Depression 03C formed on 26 September--the first CPHC
advisory at 26/2100 UTC placed the center in the far western portion of
the Central North Pacific region about 585 nm west-southwest of Johnston
Island. Unlike TD-02C, the initial advisory for this system never called
for it to reach tropical storm intensity, and in this case the forecast
verified. This depression was never well-organized and CPHC issued only
three advisories on the system. The final advisory, issued at 27/0900
UTC, noted that there was doubt as to whether or not a closed circulation
existed, and given that the environment was quite hostile with dry mid-
level air and increasing shear, any remaining circulation would likely
soon dissipate. At the time of the final CPHC advisory TD-03C was
about to cross longitude 180, and JMA issued four bulletins on the system
as a weak tropical depression through 28/0600 UTC.
The online Wikipedia reports for the Eastern Pacific cyclones may
be accessed at the following URL:
http://en.wikipedia.org/wiki/2006_Pacific_hurricane_season>
A more expanded report is available for Hurricane Lane. The link to
this is included in the report on Lane below.
HURRICANE LANE
(TC-13E)
13 - 17 September
-------------------------------------
A. Introduction
---------------
Hurricane Lane was a fairly small but intense tropical cyclone which
formed and remained within about 100 nm of the Mexican coastline. Lane
became the first hurricane of Category 3 or higher intensity to strike
Mexico since the destructive Hurricane Kenna of October, 2002. Kenna
had peaked at 145 kts--a Category 5 hurricane--before striking the
coast near the fishing village of San Blas as a 120-kt Category 4
hurricane. Hurricane Kenna was the last of three Category 5 hurricanes
which roamed Eastern Pacific waters during the 2002 season, the others
being Elida and Hernan.
B. Synoptic History
-------------------
A tropical wave passing several hundred miles south of the Gulf of
Tehuantepec spawned an area of disturbed weather on 11 September which
persisted as it moved slowly westward. Convection and banding features
slowly improved and the system was classified as Tropical Depression 13E
at 2100 UTC on 13 September while located about 100 nm southwest of
Acapulco. TD-13E slowly intensified and was upgraded to Tropical Storm
Lane at 0900 UTC on 14 September while centered about 80 nm off the
Mexican coast. Lane continued to strengthen as it moved northwestward
around the western periphery of a mid-level ridge centered over Mexico.
Throughout its life the cyclone moved on a track roughly parallel to and
generally less than 100 nm off the Mexican coastline.
Since the storm posed a threat to Mexico, reconnaissance missions were
flown into the storm by the U. S. Air Force Hurricane Hunters. Based on
a peak FLW of 76 kts and a 90-min pressure drop from 989 to 985 mb, Lane
was upgraded to a hurricane at 15/2100 UTC while centered only about
35 nm west-northwest of Cabo Corrientes. Lane's track had by that time
shifted more to the north-northwest at about 8 kts. Once having reached
hurricane intensity, Lane intensified rapidly--a possibility which had
been suggested by the SHIPS model. Only three hours after reaching
hurricane intensity, Lane was a Category 2 hurricane with 85-kt winds
passing just west of the Islas Marias.
Intensification continued and at 16/0900 UTC Lane became the season's
fifth major hurricane as the MSW was upped to 100 kts, based on Dvorak
ratings of T5.5 from all three agencies. The storm was then located
about 45 nm southwest of Mazatlan, Mexico, and moving toward the north-
northwest at 9 kts. Hurricane Lane reached its peak intensity of 110 kts
at 1500 UTC. The 8-10 nm eye was embedded in cloud tops of -70 to -80 C
and had become better defined during the previous few hours. Satellite
intensity estimates remained at 102 kts from TAFB and AFWA but had
increased to 115 kts from SAB.
The center of Hurricane Lane made landfall about 20 nm southeast of
El Dorado, Mexico, around 1915 UTC. A reconnaissance plane reached the
eye of Lane just before landfall and measured a CP of 955 mb along
with maximum 700-mb FLWs of 110 kts in the southeastern eyewall. An
eyewall dropsonde in the southern eyewall just after landfall measured
a surface wind of 108 kts. Once inland the storm predictably began
to weaken rapidly over the mountainous terrain with some southwesterly
shear also aiding in the weakening process. Lane was downgraded to a
tropical storm at 17/0900 UTC, and the final TPC/NHC advisory on the
weakening depression was issued at 17/1500 UTC, placing the dissipating
surface center about 150 km east-northeast of Los Mochis, Mexico. Some
of the moisture from Lane eventually reached Texas.
C. Damage and Casualties
------------------------
Due to Lane's track near the Mexican coast, effects were felt in
several areas. In Acapulco, wave action and heavy rains caused flooding
in coastal streets. Around 200 homes were flooded and the heavy rains
were responsible for a mudslide, resulting in the death of a 7-year old
boy. Offshore, strong waves capsized a boat, leaving one person missing.
Heavy rainfall in the states of Michoacan and Jalisco (187 mm in Cajon
de Pena) also led to flooding and landslides with some fatalities
reported. In the landfall area roads were washed away and flimsy homes
destroyed with electricity poles, trees, and traffic signs blown down.
In Mazatlan strong winds and heavy rain resulted in flooded streets and
power outages. The total death toll from Hurricane Lane stands at four
with total damages estimated around $110 million (USD).
Much of the above information was obtained from the online Wikipedia
report on Hurricane Lane, and many more details are available in the
report. This excellent and very informative report may be accessed at
the following URL:
http://en.wikipedia.org/wiki/Hurricane_Lane_%282006%29>
(Report written by Gary Padgett)
TROPICAL STORM MIRIAM
(TC-14E)
16 - 18 September
-----------------------------------------
Tropical Storm Miriam was a short-lived and weak tropical storm which
formed in a broad area of disturbed weather extending westward from
Hurricane Lane. The system was classified as a tropical depression (14E)
at 16/0600 UTC when located roughly 450 nm southwest of Cabo San Lucas
on the southern tip of the Baja California Peninsula. TD-14E initially
moved slowly northeastward, embedded in southwesterly flow feeding into
Hurricane Lane. Operationally, the depression was upgraded to Tropical
Storm Miriam at 1800 UTC on the 16th while located approximately 400 nm
southwest of Cabo San Lucas. (In post-storm analysis it has been
determined that the depression and tropical storm stages were each
reached six hours earlier than reported operationally.)
Tropical Storm Miriam reached its peak intensity of 40 kts at 17/0300
UTC and maintained this strength for 18 hours. Northeasterly wind shear
along with inflow from a cooler and stable environment to the north
inhibited further intensification and Miriam began to weaken on the 17th.
The system was downgraded to a depression at 18/0900 UTC and the final
TPC/NHC advisory written at 18/1500 UTC. The remnant LOW moved northward
toward the Baja before dissipating on 21 September a short distance
offshore.
The official storm report on Tropical Storm Miriam, authored by James
Franklin, is available on the TPC/NHC website at the following URL:
http://www.nhc.noaa.gov/2006epac.shtml>
Some of the information above was taken from this report. No damage
or casualties are known to have resulted from Tropical Storm Miriam.
(Report written by Gary Padgett)
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for September: 1 possible tropical depression or storm **
3 tropical depressions ++
1 tropical storm ##
2 typhoons
2 super typhoons &&
** - system received repeated Dvorak ratings of T2.5 from both JTWC and
AFWA but was never started as a tropical depression, nor so
classified by JMA
++ - one of these was classified as a tropical depression by JMA only;
another formed late in month and became named tropical cyclone in
early October
## - system was classified as a minimal tropical storm by JTWC and CMA
only
&& - one of these was a visitor from the Central North Pacific
Sources of Information
----------------------
Most of the information presented below is based upon tropical
cyclone warnings and significant tropical weather outlooks issued
by the Joint Typhoon Warning Center of the U. S. Air Force and
Navy (JTWC), located at Pearl Harbor, Hawaii. In the companion
tropical cyclone tracks file, I normally annotate track coordinates
from some of the various Asian warning centers when their center
positions differ from JTWC's by usually 40-50 nm or more. All
references to sustained winds imply a 1-minute averaging period
unless otherwise noted.
Michael V. Padua of Naga City in the Philippines, owner of the
Typhoon 2000 website, normally sends me cyclone tracks based upon
warnings issued by the Japanese Meteorological Agency (JMA) and the
Philippines' Atmospheric, Geophysical & Astronomical Services
Administration (PAGASA). A very special thanks to Michael for the
assistance he so reliably provides.
In the title line for each storm I have referenced all the cyclone
names/numbers I have available: JTWC's depression number, the
JMA-assigned name (if any), JMA's tropical storm numeric designator,
and PAGASA's name for systems forming in or passing through their
area of warning responsibility.
Northwest Pacific Tropical Activity for September
-------------------------------------------------
Waters of the Northwest Pacific basin were literally crawling with
tropical systems of various intensities during the month of September.
To keep a little order, I am going to arrange this introductory
paragraph a little differently from what I usually do.
(1) Supertyphoon Ioke: This very long-lived intense tropical cyclone
formed well to the south of Hawaii in late August, becoming the
first native Central North Pacific hurricane on record to reach
Category 5 intensity. The storm struck tiny Johnston Atoll before
reaching the superlative level on the Saffir/Simpson scale and
later entered the Northwest Pacific basin as a super typhoon.
Ioke passed very near Wake Island before gradually beginning to
weaken. The storm recurved east of Japan, and in its extratropical
stages produced high waves and a severe storm surge along the
western Alaskan coastline as well as heavy rainfall over the state.
The complete report on Super Hurricane/Typhoon Ioke may be found in
the August summary.
(2) Wake Island Possible Tropical Storm of 5-7 September: A system in
the vicinity of Wake Island in early September received Dvorak
classifications supporting tropical storm intensity for a few days,
and there were QuikScat winds to 50 kts; yet, no tropical cyclone
warnings were initiated by JTWC nor was the system even referenced
as a tropical depression by JMA. Karl Hoarau was of the opinion
that this system was indeed a short-lived tropical storm. Following
is a short report, which includes Karl's track, documenting this
system.
(3) Typhoon Shanshan/Luis: Shanshan was an intense typhoon which
recurved east of Taiwan, passing over some of the southernmost
islands in the Ryukyu group. In its later stages the cyclone
struck southwestern Japan with rather significant effects. A report
on Typhoon Shanshan written by Kevin Boyle follows.
(4) Tropical Depression 15W: This was a rather short-lived, weak
depression which formed in the South China Sea on 12 September and
moved northward and inland in western Guangdong Province around
1200 UTC on 13 September. JMA estimated the winds (10-min avg) in
this system at 30 kts, but JTWC reported 30 kts (1-min avg) for only
one warning cycle, at 13/0000 UTC. A track was included for this
system in the accompanying cyclone tracks file for September.
(5) Super Typhoon Yagi: Yagi was the year's fourth typhoon to reach
JTWC's super typhoon threshold of 130 kts, peaking at 140 kts as
it recurved well southeast of Japan. A report on Super Typhoon
Yagi, authored by Kevin Boyle, follows.
(6) Tropical Storm 17W: This system was another fairly short-lived
South China Sea system, forming in the central portion of the Sea on
22 September per the analysis of the China Meteorological
Administration (CMA), the Hong Kong Observatory, and JMA. JTWC
initiated warnings on Tropical Depression 17W at 23/0000 UTC. The
depression moved on a west-northwesterly track across the South
China Sea, making landfall in Vietnam on the 25th. The system
passed just south of Hainan and brought heavy rain to that island
with the maximum value recorded being 143 mm (according to the
Wikipedia report).
Satellite classifications from JTWC, SAB and AFWA all reached
T2.5 (35 kts), and JTWC upgraded TD-17W to a 35-kt tropical storm
24/0000 UTC. However, the system appeared to weaken under strong
vertical shear and JTWC downgraded it back to depression status
only six hours later. The CMA also upgraded the system to a
tropical storm and maintained it at that status until landfall in
Vietnam. According to the online Wikipedia report, this was the
13th time since the new naming procedures were put into place in
2000 that JTWC had recognized a tropical storm not named by JMA.
It was also the 3rd time that CMA had recognized a tropical storm
not named by JMA, the other cases being in 2000 and 2004. A track
for this system may be found in the companion cyclone tracks file.
(7) Weak JMA Tropical Depression: A tropical disturbance was located
on 24 September a few hundred miles east-northeast of Kwajalein.
JTWC mentioned this as an area with 'poor' development potential,
noting that deep convection was pulsing over a weak LLCC evident
in microwave imagery. JMA referenced this system as a weak tropical
depression in their High Seas Bulletin at 24/1800 UTC. However,
six hours later it was referenced only as a 'low pressure area'. It
was subsequently followed westward for another couple of days but
did not develop.
(8) Typhoon Xangsane/Milenyo: Xangsane was the first in a series of
deadly, destructive typhoons to plague the Philippines during the
fall months. Xangsane was notable for its extremely rapid
intensification prior to landfall, plus maintaining its strength
while crossing the archipelago. A report on Typhoon Xangsane by
Kevin Boyle follows.
(9) Beginnings of Tropical Storm Bebinca: A system in late September
west of the Marianas was classified as a weak tropical depression
by JMA. On 1 October JTWC initiated warnings on the system as
Tropical Depression 19W, and a couple of days later was upgraded
to Tropical Storm Bebinca. A report on Bebinca will be included
in the October summary.
(10) Remnants of Central North Pacific Depressions: Two short-lived
tropical depressions formed in late September in the western portion
of the Central North Pacific region. The first, TC-02C, weakened
well to the east of the Dateline, but its remnants held together
and moved westward into the eastern Marshall Islands. Tom Wright,
Chief Meteorologist, 3D Research/RTS Weather on Kwajalein, reports
that they received almost 3.5 inches (89 mm) of rain from around
25-27 September from the remnants of TD-02C, and Ailingalaplap (to
the south of Kwajalein) received about 4 inches (102 mm) on the
27th alone. However, winds at Kwajalein were only about 12 kts in
association with the former tropical depression's remnants. Radar
revealed a broad circulation with several small circulations, or
eddies, embedded within the larger circulation.
Tropical Depression 03C was downgraded by CPHC on 27 September just
east of the Dateline, but its remnants continued tracking westward
into the Northwest Pacific basin also. JMA picked up the former
TD-03C as a weak tropical depression at 13.0N/180.0E at 27/1200 UTC
and carried it as a weak depression in their High Seas Bulletins for
about 24 hours.
The online Wikipedia reports for the Northwestern Pacific cyclones may
be accessed at the following URL:
http://en.wikipedia.org/wiki/2006_Pacific_typhoon_season>
More expanded reports are available for Typhoons Shanshan and Xangsane.
The links to these are included in the respective reports below.
POSSIBLE TROPICAL STORM
(NRL Invest 92W)
5 - 7 September
-------------------------------------------
A tropical system in the vicinity of Wake Island in early September
may very well have been a tropical storm which remained unnamed and
unnumbered. JTWC and AFWA both assigned Dvorak ratings of T2.5/2.5,
plus there were some QuikScat data showing uncontaminated 50-kt wind
vectors within the northern side of the circulation. However, SAB
never assigned a CI number greater than 2.0, and neither JTWC nor JMA
classified the system as a tropical depression.
I asked Dr. Karl Hoarau of Cergy-Pontoise University near Paris to
perform a Dvorak analysis of this system and construct a track, which
is included below. (A special thanks to Karl for his efforts.)
According to Karl's track a 25-kt tropical depression had formed by
05/0600 UTC about 300 nm south-southwest of Wake Island, moving north-
northeastward and reaching tropical storm intensity around 06/0000 UTC
when centered approximately 250 nm south of the island. Dvorak ratings
from both AFWA and JTWC were T2.5/2.5 at 05/2330 UTC, and JTWC issued
a TCFA for the LOW at 06/0200 UTC. Convection had continued to develop
near a well-defined LLCC, and an upper-level analysis indicated that a
TUTT cell to the northwest and near-equatorial ridging to the southwest
were providing excellent poleward and equatorward outflow. Also, as
noted above, some recent QuikScat data had shown uncontaminated wind
vectors of 50 kts on the northern side of the circulation.
Based on Karl's analysis, the system was at tropical storm intensity
for 18 hours, peaking at 40 kts at 06/0600 UTC. The cyclone reached
the easternmost point of its trajectory at 06/1200 UTC when it was
located approximately 125 nm southeast of Wake Island. Afterwards, it
began to curve to the north-northwest and was located about 100 nm
north-northeast of Wake Island at 07/0600 UTC when Karl's track ends.
Per his analysis, the system had weakened to 25 kts by that time.
However, Dvorak ratings from JTWC and AFWA were still in general holding
around T2.5 and JTWC issued a second TCFA at 07/0200 UTC. Convection
was still flaring around a partially-exposed LLCC located within an
environment of moderate vertical shear. A third TCFA was issued at
08/0200 UTC, the system then being located about 345 nm north of Wake
Island and with increasing organization. However, at 09/0030 UTC the
TCFA was cancelled with the system then located approximately 450 nm
north-northwest of Wake Island. Satellite imagery revealed an
elongation and breakdown of the LLCC. The entrainment of drier air in
the mid levels on the western periphery, increased vertical wind shear,
and the system's movement into a region of cooler SSTs had resulted in
a transformation from a barotropic system into a more baroclinic one.
It is indeed a little puzzling why, with intensity estimates of 35 kts
for more than two days from two different agencies, no warnings were
ever issued for this system, even as a tropical depression. However,
SAB never estimated the system above T2.0/2.0, and this was at 10/0233
UTC--well after JTWC had cancelled the TCFA. SAB then weakened the
system to T1.5/2.0 at 10/0833 and 10/1433 UTC, declaring it extratropical
at 11/0233 UTC. Furthermore, JMA never mentioned this system as a
tropical depression in their High Seas Bulletins, and typically that
agency "starts" systems as tropical depressions before JTWC does.
Following are the track positions and intensities supplied by Karl
Hoarau:
Storm Name: None Cyclone Number: None Basin: NWP
(NRL Invest Number 92W)
Date Time Lat Lon Cent MSW MSW Remarks
(GMT) Press 1-min 10-min
(mb) (kts) (kts)
-------------------------------------------------------------------------
07 SEP 05 0600 14.4 N 166.1 E 25
07 SEP 05 1200 15.4 N 166.6 E 30
07 SEP 05 1800 16.2 N 167.0 E 30
07 SEP 06 0000 16.6 N 167.4 E 35
07 SEP 06 0600 17.2 N 167.9 E 40
07 SEP 06 1200 18.0 N 168.2 E 35
07 SEP 06 1800 19.0 N 168.0 E 30
07 SEP 07 0000 19.9 N 167.7 E 30
07 SEP 07 0600 20.9 N 166.9 E 25
Note: Even though JTWC and AFWA were assigning Dvorak intensity
estimates implying the existence of a tropical depression or even
a tropical storm after 07/0600 UTC, I chose not to attempt to extend
the track beyond the time frame of Karl�s analysis. My purpose is
primarily to simply document the existence of this system.
(Report written by Gary Padgett with track by Karl Hoarau)
TYPHOON SHANSHAN
(TC-14W / TY 0613 / LUIS)
9 - 22 September
---------------------------------------------
Shanshan: contributed by Hong Kong, China, is a fairly
common pet name for young girls
A. Storm Origins
----------------
Shanshan was initially mentioned as a suspect area in JTWC�s STWO at
1000 UTC 8 September when an area of convection developed approximately
240 nm west of Guam. The disturbance was located under a weak vertical
wind shear environment, southwest of a TUTT cell, with weak eastward and
moderate equatorward outflow. After further development, a TCFA was
issued at 1230 UTC 9 September, followed by the first warning at 10/0000
UTC. Moving northwestwards, Tropical Depression 14W intensified and was
upgraded to a 40-kt tropical storm at 10/1200 UTC while located
approximately 660 nm southeast of Naha, Okinawa. The tropical cyclone
was named Shanshan at the same time when JMA raised their 10-min avg MSW
estimate to 35 kts.
B. Synoptic History
-------------------
Tropical Storm Shanshan continued to intensify as it drifted north-
westward at 6-8 kts along the periphery of a subtropical ridge and was
upgraded to a 70-kt typhoon at 1200 UTC 11 September, being approximately
530 nm southeast of Naha, Okinawa. The MSW reached 90 kts at 12/0000
UTC, and this intensity was maintained for 24 hours as the storm turned
westwards. Typhoon Shanshan weakened on 13 September as convergence
aloft suppressed the polar outflow. The tropical cyclone began to
strengthen again on 14 September, and shortly after turning northwards
towards a weakness in the ridge, reached a peak intensity of 120 kts at
15/1200 UTC.
Shanshan passed through the southern Ryukyu Islands late on 15
September while maintaining 120-kt winds and started to accelerate
northeastwards on 16 September as it began to interact with a mid-
latitude trough over eastern China. The system began to weaken and
undergo extratropical transition on 17 September as it raced north-
northeastwards towards the Japanese island of Kyushu. Shanshan skirted
the western coasts of Kyushu and Honshu and was downgraded to a tropical
storm at 17/1800 UTC, the time of JTWC�s final warning. JMA lowered
their MSW to tropical storm levels at 18/0000 UTC but maintained
Shanshan as a tropical storm for two more days, not declaring the system
extratropical until 20/0000 UTC. Shanshan was located in the Sea of
Japan at 19/1800 UTC, but by 20/0000 UTC had raced northeastward across
northern Hokkaido into the North Pacific. Thereafter the extratropical
storm slowed its forward motion and moved slowly up the chain of the
Kuril Islands as it gradually weakened. The final reference to the
system in Japan�s High Seas Bulletins placed a 25-kt LOW near the
southern tip of the Kamchatka Peninsula at 22/1200 UTC.
The highest MSW (10-min avg) and minimum CP estimated for Typhoon
Shanshan by JMA were 100 kts and 925 hPa, respectively. PAGASA referred
to this cyclone as Typhoon Luis, and the peak MSW estimated by that
agency during the time that Luis was located within PAGASA's AOR was
80 kts (10-min avg).
C. Meteorological Observations
------------------------------
The eye of Typhoon Shanshan passed very near Ishigakijima in the
southern Ryukyus around 2100 UTC on 15 September. At 2100 UTC the
weather station (24.3N/124.2E, Alt. 6 m) reported a SLP of 929 hPa
and an attendant 10-min avg wind of SSE 48 kts. The center of the
eye at the time was about 12 nm due west of the station, indicating
that the station was likely under the eastern eyewall. An hour earlier
the Ishigakijima station reported sustained winds of 88 kts. However,
these should be understood to be the winds at that particular hour and
not necessarily the strongest winds experienced by the station during
the typhoon's passage.
The online Wikipedia report on Shanshan indicates that a peak gust
of 130 kts was reported on Ishigakijima, while on Iriomote a peak gust
of 137 kts was recorded. On Ishigakijima rainfall rates of 50 mm per
hour were also reported.
Later the eye of Shanshan passed about 120 nm west of Okinawa with
Naha reporting SSW winds of 41 kts, gusting to 61 kts.
D. Damage and Casualties
------------------------
Typhoon Shanshan brought strong winds and heavy rains to Okinawa,
South Korea and Japan. Over 25,000 homes in Ishigaki, Okinawa, were
without electricity after high winds brought down utility poles. In
Japan, eleven people were reported dead and 260 injured. Typhoon
Shanshan caused damages up to US$4.9 million. One death was reported
from South Korea where the storm knocked out power to nearly 4000 homes.
A very detailed online report on Typhoon Shanshan/Luis may be found
at the following URL:
http://en.wikipedia.org/wiki/Typhoon_Shanshan_%282006%29>
(Report written by Kevin Boyle with additions by Gary Padgett)
SUPER TYPHOON YAGI
(TC-16W / TY 0614)
13 - 27 September
--------------------------------------
Yagi: contributed by Japan, is the Japanese word for goat
A. Introduction and Storm Origins
---------------------------------
The fourth Northwest Pacific tropical cyclone of 2006 to achieve super
typhoon intensity, Yagi traced a slow clockwise loop for three days
before passing well north of the Marianas and recurving southeast of
Japan.
On 16 September an area of convection developed approximately 685 nm
east-northeast of Guam, and was first mentioned as a suspect area in
JTWC�s STWO at 0000 UTC when animated multi-spectral satellite imagery
depicted flaring convection south and east of a weak LLCC. The
disturbance was located in a weak to moderate wind shear environment
under a developing upper-level anticyclone. After further development,
a TCFA was issued at 16/1730 UTC followed by the first warning on
Tropical Depression 16W at 17/0000 UTC. TD-16W was upgraded to a 35-kt
tropical storm at 17/0600 UTC. At the same time, JMA raised their 10-min
avg MSW to 35-kts and assigned the name Yagi. (Editor�s Note: JMA first
identified the pre-Yagi system as a weak tropical depression in their
High Seas Bulletins as early as 13/1200 UTC when it was located near
11.0N/156.0E. That the system was diffuse and difficult to track is
attested to by several significant relocations over the next few days
before a definite center began to consolidate on the 16th.)
B. Synoptic History
-------------------
Initially located in a weak steering environment, Yagi slowly executed
a slow clockwise loop while intensifying and was upgraded to a 65-kt
typhoon at 1800 UTC 18 September while located approximately 845 nm east-
northeast of Saipan. After completing the loop, Yagi resumed a westward
track as it became increasingly influenced by a building subtropical
ridge southeast of Japan. Typhoon Yagi continued to intensify, reaching
super typhoon strength at 21/0600 UTC while turning towards the west-
northwest. Yagi peaked at 140 kts at 21/1200 UTC and maintained this
intensity for 18 hours on 21-22 September, passing well north of the
Mariana Islands.
At 22/0600 UTC Super Typhoon Yagi was centred approximately 70 nm
east of Iwo Jima, the island lying just within the radius of 50-kt winds.
Moving progressively poleward on 22 September, Yagi began to weaken due
to increasing wind shear associated with the mid-latitude westerlies.
The tropical cyclone completed recurvature on 23 September and underwent
extratropical transition on 24 September (per JTWC�s analysis). JMA
downgraded Yagi to a severe tropical storm at 24/1200 UTC and maintained
it as a tropical system through 25/0000 UTC. The extratropical storm
continued moving east-northeastwards, crossing the Dateline early on the
27th. The final reference to ex-Yagi in JMA�s bulletins placed a still-
potent 50-kt storm just south of the Aleutian Islands at 27/0600 UTC.
JMA estimated a maximum intensity of 110 kts (10-min avg) and a
minimum CP of 910 mb. This cyclone did not enter PAGASA�s AOR.
C. Damage and Casualties
------------------------
There were no damages or casualties reported in association with Super
Typhoon Yagi.
(Report written by Kevin Boyle)
TYPHOON XANGSANE
(TC-16W / TY 0615 / MILENYO)
25 September � 2 October
------------------------------------------------
Xangsane: contributed by Lao People�s Democratic Republic (Laos), is
the Laotian word for elephant
A. Introduction and Storm Origins
---------------------------------
The first in a veritable parade of intense, destructive typhoons to
strike the Philippines during the fall, Typhoon Xangsane originated from
a fairly broad circulation within the monsoon trough east of the
Philippines. It intensified quickly to near super typhoon strength
before slamming into the Philippines on 27 September. Xangsane remained
a powerful typhoon throughout its westward journey across the Philippines
and across the South China Sea, finally making landfall on the Vietnamese
coast on 30 September.
The initial reference to the pre-Xangsane disturbance was in JTWC�s
STWO at 0600 UTC 23 September when an area of convection persisted
approximately 90 nm north-northwest of Palau. Upper-air analysis
revealed a low to moderate wind shear environment and favourable
divergence aloft. After the issuance of a TCFA early on 25 September,
the first warning on Tropical Depression 18W was released at 25/1200
UTC. TD-18W was quickly upgraded to a 35-kt tropical storm at 25/1800
UTC, located approximately 460 nm east-southeast of Manila, Philippines.
The tropical cyclone was christened Xangsane at 26/0000 UTC when JMA
raised their 10-min avg MSW to 35 kts. (PAGASA had began issuing
statements on the system, dubbed Tropical Depression Milenyo, at
25/0000 UTC.)
B. Track History
----------------
Tropical Storm Xangsane intensified on 26 September and was upgraded
to a typhoon at 1800 UTC while located approximately 340 nm east-
southeast of Manila. From 26/1800 UTC to 27/0600 UTC Typhoon
Xangsane/Milenyo underwent an explosive deepening phase before reaching
its maximum intensity of 125 kts at 27/1200 UTC, making landfall over
Samar, Philippines, around that time. After striking Samar, Milenyo�s
west-northwestward track kept the tropical cyclone over land for much
of its tenure over the Philippine Archipelago. As a result, the
cyclone gradually lost strength, passing over the Metro-Manila area
of southern Luzon early on 28 September. Xangsane/Milenyo remained a
major typhoon while traversing the Philippines and emerged into the
South China Sea at around 28/1200 UTC.
Changing onto a westerly course under the steering influence of a
mid-level ridge, Typhoon Xangsane began to strengthen once again,
attaining a secondary peak intensity of 115 kts at 29/0600 UTC while
located roughly a third of the way across the South China Sea. After
maintaining a MSW of 115 kts for over 24 hours, the tropical cyclone
began to slowly weaken as it approached Vietnam. Continuing westwards,
the system came ashore near Hue, Vietnam, early 1 October with a MSW of
80 kts. JTWC issued their final warning at 01/0600 UTC. From there,
JMA tracked Xangsane westward across much of southeastern Asia,
downgrading it to a tropical storm at 01/1200 UTC and to a tropical
depression at 02/0000 UTC.
The maximum intensity of Typhoon Milenyo as estimated by PAGASA was
75 kts (10-min avg). JMA estimated a peak intensity of 90 kts (10-min
avg) and a minimum CP of 940 mb.
C. Damage and Casualties
------------------------
Typhoon Milenyo/Xangsane caused widespread damage in the Philippines,
and was the worst storm to affect Manila since Typhoon Angela/Rosing in
1995. A total of 197 lives were lost in the Philippines with damages
to property and agriculture totaling 5.9 billion Filipino pesos.
Typhoon Xangsane also badly impacted Vietnam. The storm caused
nearly 10 trillion Vietnamese dong worth of damage and 71 people lost
their lives. As the storm moved into neighbouring Thailand, torrential
rains caused severe flooding. There were no reports of casualties.
Much more information on the impact of Typhoon Xangsane in both the
Philippines and Vietnam may be found in the online Wikipedia report at
the following URL:
http://en.wikipedia.org/wiki/Typhoon_Xangsane>
D. Additional Information
-------------------------
Following is part of an e-mail posted by Michael V. Padua of Naga
City, Philippines, to a tropical cyclone discussion group (slightly
edited):
"The reincarnation of Xangsane was memorable...the storm struck major
cities from southern Luzon up to the Metro Manila. Lucky I am that the
eye just passed 30 km to the south of Naga City...and the damage was
minimal...not a single scratch was seen on my Davis Vantage Pro (weather
station).
"Here's an interesting story...my uncle was attending a seminar in
Legazpi when Xangsane arrived. He was driving back to Naga when the
typhoon arrived. Upon its passage he stopped at a nearby gasoline
station around 7:30 pm to take shelter as very strong winds began
to rampage near the city of Legazpi or over the town of Daraga.
While over the Shell Gas station, a sudden lull occurred from 7:45 pm
up to 8:15 pm... a quietness of 30-mins!!! While inside the eye he
saw flickering lightning flashes on all sides of the horizon. Then the
wind returned with full-force, even stronger than the first. He told
me that the eyewall left the place around 10:30 pm (during that time
my weather station began recording high wind speeds). Overall, the
damage down south of Naga is worst, especially the cities of Iriga and
Legazpi.
"Before the eye passed over Legazpi, my uncle heard over the radio
that 30-foot waves with 20 feet of storm surge began hurling towards the
port of Legazpi, reaching into the low-lying areas of the main city
proper. Cars and other vehicles were submerged during the surge.
Wow! Horrendous indeed!"
Some observations recorded by Michael on his weather station follow:
(1) Lowest barometric pressure - 986.4 hPa at 27/1530 UTC
(2) Highest wind speed - East 57.3 kts at 27/1516 UTC
(3) 24-hour rainfall - 83.1 mm from 26/1600 UTC to 27/1600 UTC
78.7 mm from 27/1600 UTC to 28/1600 UTC
(4) 48-hour rainfall - 161.8 mm from 27/1600 UTC to 29/1200 UTC
(5) Storm total rainfall - 189.2 mm from 25/1600 UTC to 28/1600 UTC
(6) Maximum rain rate - 137.1 mm/hr from 27/1721 UTC to 27/1722 UTC
(Note that this is the maximum hourly rain rate based on the peak
1-min rainfall measured. No, 5.4 inches did not fall in one
minute!)
(Report written by Kevin Boyle with an addition by Michael Padua)
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for September: 2 depressions **
1 tropical cyclone of gale intensity ++
1 severe cyclonic storm
** - no warnings issued on these systems by JTWC
++ - system was treated only as a depression by IMD
Sources of Information
----------------------
Most of the information presented below is based upon tropical
cyclone warnings and significant tropical weather outlooks issued
by the Joint Typhoon Warning Center of the U. S. Air Force and
Navy (JTWC), located at Pearl Harbor, Hawaii. Occasionally some
information may be gleaned from the daily tropical weather outlooks
and other bulletins issued by the Indian Meteorological Department
(IMD), which is the World Meteorological Organization's Regional
Specialised Meteorological Centre (RSMC) for the basin.
The reported maximum sustained winds (MSW) are based on a 1-minute
averaging period, which is used by all U. S. civilian and military
weather services for tropical cyclone warnings. For synoptic
observations in the North Indian Ocean region, both 10-minute and
3-minute average winds are employed, but IMD makes no attempt to
modify the Dvorak scale for estimating tropical cyclone intensity;
hence, a 1-minute average MSW is implied. In the North Indian Ocean
basin JTWC usually does not initiate warnings until a system has
become well-organized and likely to attain tropical storm status
within 48 hours.
North Indian Ocean Tropical Activity for September
--------------------------------------------------
The northern Bay of Bengal had been quite prolific during August,
producing several weak depressions. This trend continued into early
September with IMD identifying a depression on the 3rd, centered at
1200 UTC about 100 nm southeast of Balasore. The system moved
westward and crossed the coast near Chandbali around 0100 UTC on
4 September and slowly weakened thereafter. This system was
referenced in the STWOs from JTWC as an area with a 'poor' potential
for development.
A couple of quiet weeks ensued before activity resumed. Based on
very sketchy information in the IMD bulletins and on a report on the
Wikipedia website, IMD upgraded a low-pressure area near Jamshedpur to
depression status on 21 September. This city lies well inland, so likely
this system was a monsoon depression. Over the next two days the
depression moved northward into the state of Bihar, weakening to a low-
pressure area on the 24th. According to the Wikipedia report, torrential
downpours associated with this system caused flooding that led to 170
fatalities and left around 375,000 persons homeless.
There were two storms in the North Indian Ocean for which warnings
were issued. Severe Cyclonic Storm Mukda formed in the northeastern
Arabian Sea on 20 September and remained quasi-stationary for most of
its existence while intensifying to near hurricane force. During the
final days of the month, another weak northern Bay of Bengal system was
designated Tropical Cyclone 05B by JTWC. Short reports on Mukda and
TC-05B follow.
The online Wikipedia reports for the North Indian Ocean cyclones may
be accessed at the following URL:
http://en.wikipedia.org/wiki/2006_North_Indian_cyclone_season>
SEVERE CYCLONIC STORM MUKDA
(TC-04A / ARB0601)
20 - 25 September
-----------------------------------------------
Mukda: contributed by Thailand
An area of convection developed and persisted on 18 September
approximately 170 nm west-northwest of Mumbai (Bombay), India. An
18/1344 UTC QuikScat image revealed flaring convection within an area
of surface troughing. Upper-level analysis depicted favorable
divergence aloft with low to moderate vertical shear. By the next day
the disturbance had moved to a position about 250 nm west of Mumbai
and appeared to be have become slightly better organized, so JTWC
raised the potential for further development to 'fair'. The system
continued to move westward away from India and at 20/1800 UTC lay
approximately 350 nm west of Mumbai. Animated multi-spectral imagery
depicted a partially-exposed LLCC with deep convective banding wrapping
into the western quadrant. Based on satellite intensity estimates,
the system by this time was sufficiently organized to be classified
as a tropical depression with winds likely around 30 kts. At 20/2300
UTC JTWC issued a TCFA for the system as convective organization
continued to improve.
The first JTWC warning on TC-04A was issued at 21/0000 UTC with the
center located about 315 nm south of Karachi, Pakistan, drifting west
at 4 kts with the MSW estimated at 35 kts. The intensity had increased
to 45 kts by 21/1200 UTC where it reached a plateau for a day or so.
Steering currents had become very weak by 1200 UTC and the storm moved
very little over the next few days. At 22/0000 UTC the MSW was still
estimated at 45 kts, but there were signs that TC-04A was strengthening.
A 21/2107 UTC AMSR-E pass had depicted tightly-curved convective banding
and a formative eye. IMD had designated the system as a depression at
21/0300 UTC, upped it to deep depression status at 1200 UTC, and at
22/0000 UTC named the system Cyclonic Storm Mukda.
Mukda continued to intensify, reaching an estimated peak intensity of
60 kts by 22/1800 UTC--this being based on JTWC's operational warning
intensity. It seems very likely that Mukda reached hurricane intensity
on 22 September. JTWC's satellite analyst rendered a Dvorak rating of
T4.0/4.0 at 22/1730 UTC, SAB's rating was T4.5/4.5 at 22/1430 UTC, and
AFWA returned ratings of T4.5/4.5 for several hours on the 22nd. The
IMD upgraded Mukda to a severe cyclonic storm early on the 23rd, implying
peak winds between 48 and 63 kts. Regardless of its intensity, Mukda
didn't go anywhere--it remained quasi-stationary in the general area
roughly 250-300 nm south of Karachi throughout its life as a cyclonic
storm. JTWC dropped the MSW to 55 kts at 23/0600 UTC, and Mukda's
intensity continued to steadily drop, reaching minimal tropical storm
intensity of 35 kts by 24/0000 UTC with the storm still essentially
stationary. JTWC issued their final warning on Mukda at 24/1800 UTC,
and by 25/0000 UTC, the winds had dropped to about 25 kts based on
a consensus of satellite intensity estimates. The remnants of Mukda
hung around for several days in the northern Arabian Sea, gradually
drifting westward. Convection would occasionally flare up near the
still well-defined LLCC, but no serious attempts at regeneration were
observed.
No damage or casualties are known to have resulted from Severe
Cyclonic Storm Mukda.
(Report written by Gary Padgett)
TROPICAL CYCLONE
(TC-05B)
28 - 30 September
-------------------------------------
A STWO issued by JTWC at 1800 UTC on 27 September noted that an area
of convection had formed approximately 420 nm southeast of Calcutta,
India, and was moving westward into the Bay of Bengal. A LLCC was
in evidence and vertical wind shear in the region was low. Based on
satellite intensity estimates the system had become a 30-kt tropical
depression by 28/0600 UTC when located about 300 nm south-southeast of
Calcutta. JTWC issued the first warning on TC-05B at 1200 UTC with
the system then passing 250 nm south of Calcutta, moving toward the
west-northwest at 13 kts. The initial warning intensity was 35 kts,
which was the system�s peak intensity per JTWC�s warnings.
Guided by a mid-level steering ridge, TC-05B continued westward
and made landfall near Gopalpur around 29/1200 UTC. With the center
moving inland, JTWC issued their third and final warning on the system
at this time. This location is also approximately 290 nm southwest of
Calcutta. AFWA returned a Dvorak rating of T3.5/3.5 (55 kts) at 28/1800
UTC, suggesting that the system might possibly have been slightly
stronger than analyzed by JTWC. However, the IMD never upgraded this
system to deep depression status, implying that in their opinion the
MSW never reached 30 kts.
No damage or casualties resulting from Tropical Cyclone 05B have been
reported.
(Report written by Gary Padgett)
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for September: No tropical cyclones
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for September: No tropical cyclones
*************************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for September: No tropical cyclones
*************************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for September: No tropical cyclones
*************************************************************************
SPECIAL FEATURE - SOURCES OF TROPICAL CYCLONE INFORMATION
The purpose of this section is to list some websites where many and
varied types of tropical cyclone information are archived. Many readers
will know about these already, but for the benefit of those who don't,
I wanted to include them.
(1) Aircraft Reconnaissance Information
---------------------------------------
Various types of messages from reconnaissance aircraft may be
retrieved from the following FTP site:
ftp://ftp.nhc.noaa.gov/pub/products/nhc/recon/>
Information regarding how to interpret the coded reconnaissance
messages may be found at the following URL:
http://www.nhc.noaa.gov/reconlist.shtml>
Links are also included to websites with further information about the
U. S. Air Force 53rd Weather Reconnaissance Squadron and the NOAA Air-
craft Operations Center.
(2) Archived Advisories
-----------------------
All the advisory products (public advisories, forecast/advisories,
strike probabilities, discussions, various graphics) issued by TPC/NHC
are archived on TPC's website. For the current year (using 2006 as an
example), the archived products can be found at:
http://www.nhc.noaa.gov/archive/2006/index.shtml>
Links to tropical products archives for earlier years are available at
the following URL:
http://www.nhc.noaa.gov/pastall.shtml>
JTWC warnings for past storms are archived on the NRL Monterrey website:
http://www.nrlmry.navy.mil/tc_pages/tc_home.html>
On the NRL site, the link to past years can be found in the upper left
corner of the screen.
I am not aware at the moment of any other TCWC which archives all
its tropical cyclone warning/advisory products for public access, but
if I learn of any, I will add them to this list.
(3) Satellite Imagery
---------------------
Satellite images of tropical cyclones in various sensor bands are
available on the NRL Monterrey and University of Wisconsin websites,
courtesy of Jeff Hawkins and Chris Velden and their associates. The
links are:
http://www.nrlmry.navy.mil/tc_pages/tc_home.html>
http://cimss.ssec.wisc.edu/tropic/tropic.html>
On the NRL site, the link to past years can be found in the upper left
corner of the screen. For the CIMSS site, a link to data archives is
located in the lower left portion of the screen.
Additional tropical satellite imagery, along with looping ability for
composite microwave imagery for the Western Hemisphere north of the
equator, can be found at:
(1) For the Eastern North Pacific:
http://www.ssd.noaa.gov/PS/TROP/trop-epac.html>
(2) For the Atlantic, Gulf of Mexico and Caribbean Sea:
http://www.ssd.noaa.gov/PS/TROP/trop-atl.html>
I'm sure there are other sites with available imagery available, and
as I learn of them, I will add the links to this list.
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EXTRA FEATURE
In order to shorten the amount of typing in preparing the narrative
material, I have been in the habit of freely using abbreviations and
acronyms. I have tried to define most of these with the first usage
in a given summary, but I may have missed one now and then. Most of
these are probably understood by a majority of readers but perhaps a
few aren't clear to some. To remedy this I developed a Glossary of
Abbreviations and Acronyms which I first included in the August, 1998
summary. I don't normally include the Glossary in most months in
order to help keep them from being too long. If anyone would like to
receive a copy of the Glossary, please e-mail me and I'll be happy
to send them a copy.
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AUTHOR'S NOTE: This summary should be considered a very preliminary
overview of the tropical cyclones that occur in each month. The cyclone
tracks (provided separately) will generally be based upon operational
warnings issued by the various tropical cyclone warning centers. The
information contained therein may differ somewhat from the tracking and
intensity information obtained from a "best-track" file which is based
on a detailed post-seasonal analysis of all available data. Information
on where to find official "best-track" files from the various warning
centers will be passed along from time to time.
The track files are not being sent via e-mail. They can be retrieved
from the archive sites listed below. (Note: I do have a limited e-mail
distribution list for the track files. If anyone wishes to receive
these via e-mail, please send me a message.)
Both the summaries and the track files are standard text files
created in DOS editor. Download to disk and use a viewer such as
Notepad or DOS editor to view the files.
The first summary in this series covered the month of October,
1997. Back issues can be obtained from the following websites
(courtesy of Michael Bath, Michael V. Padua, Michael Pitt, Chris
Landsea, and John Diebolt):
http://australiasevereweather.com/cyclones/>
http://www.typhoon2000.ph>
http://mpittweather.com>
ftp://ftp.aoml.noaa.gov/hrd/pub/landsea/padgett/>
http://www.tropicalcyclone2005.com/>
Another website where much information about tropical cyclones may
be found is the website for the UK Meteorological Office. Their site
contains a lot of statistical information about tropical cyclones
globally on a monthly basis. The URL is:
http://www.metoffice.gov.uk/weather/tropicalcyclone>
TROPICAL CYCLONE REPORTS AVAILABLE
JTWC now has available on its website the Annual Tropical Cyclone
Report (ATCR) for 2004 (2003-2004 season for the Southern Hemisphere).
ATCRs for earlier years are available also.
The URL is: https://metocph.nmci.navy.mil/jtwc.html>
Also, TPC/NHC has available on its webpage nice "technicolor"
tracking charts for the 2005 Atlantic and Eastern North Pacific
tropical cyclones; also, storm reports for all the 2005 Atlantic
and Eastern North Pacific cyclones are now available, as well as
track charts and reports on storms from earlier years.
The URL is: http://www.nhc.noaa.gov>
A special thanks to Michael Bath of McLeans Ridges, New South Wales,
Australia, for assisting me with proofreading the summaries.
PREPARED BY
Gary Padgett
E-mail: [email protected]
Phone: 334-222-5327
Kevin Boyle (Northwest Pacific)
E-mail: [email protected]
Simon Clarke (Northeast Australia/Coral Sea, South Pacific)
E-mail: [email protected]
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Document: summ0609.htm
Updated: 26th January 2007 |
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