[Index]
Monthly Global Tropical Cyclone Summary November 2003
[Summaries and Track Data] [Prepared by Gary Padgett]
| Tropical
Cyclones
[Index] |
Monthly Global Tropical Cyclone Summary November 2003 [Summaries and Track Data] [Prepared by Gary Padgett] |
MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
NOVEMBER, 2003
(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.)
*************************************************************************
NOVEMBER HIGHLIGHTS
--> Another super typhoon roams Western Pacific
--> Central Philippines affected by tropical storm
--> Hurricane-intensity cyclone in Arabian Sea
--> First tropical cyclone (hurricane) of season in Southwest Indian
*************************************************************************
***** Feature of the Month for November *****
TROPICAL CYCLONE CLIMATOLOGICAL DATA
for the SOUTHERN HEMISPHERE and SOUTH INDIAN OCEAN
A. Introduction
---------------
For the monthly feature in the June, 2003, summary I included some
tropical cyclone climatological information for the North Indian Ocean.
This month's feature is the first of three highlighting similar sets
of data for the Southern Hemisphere. The source for the data was a
a set of tropical cyclone tracks sent to me by Mr. Charles Neumann.
These had been prepared in association with a hurricane risk analysis
(HURISK) study he was performing for the U. S. Navy. Earlier studies
had been accomplished for the Atlantic and North Pacific basins. The
tracks and intensities were based upon available data sets for the
various Southern Hemisphere basins from the regional warning centers,
and from 1980 onward, JTWC's Best Track files were utilized as an
additional source of data.
The data set begins with the 1960-61 Southern Hemisphere cyclone
season and extends through 2001-2002, and I have included the entire
period. While the annual number of intense tropical cyclones
(MSW < 100 kts) increases somewhat around 1970, the numbers of tropical
storms and hurricanes during the pre-1970 period are not significantly
different than for years following the advent of meteorological
satellites. No doubt in pre-satellite years many cyclones were not
detected, especially in the vast island-free South Indian Ocean. But
in some areas, such as northern Australia, where most storms form near
land and affect the coastline, and also in the island-rich South Pacific,
it is likely that most significant tropical cyclones were at least
detected (even if not tracked accurately) before operational satellite
coverage became complete in the late 1960s.
B. Definition of Parameters
---------------------------
The following definitions apply:
NS - a tropical cyclone with a peak 1-min avg MSW >= 34 kts
H - a tropical cyclone with a peak 1-min avg MSW >= 64 kts
IH - a tropical cyclone with a peak 1-min avg MSW >= 96 kts
NSD - four 6-hour periods in which a NS is operating
HD - four 6-hour periods in which a H is operating
IHD - four 6-hour periods in which an IH is operating
NTC - (((Total NS/Avg NS) + (Total H/Avg H) + (Total IH/Avg H) +
(Total NSD/Avg NSD) + (Total HD/Avg HD) +
(Total IHD/Avg IHD))/6) x 100%
I have included another seasonal measure of the overall tropical
cyclone level of activity which I developed--the Tropical Cyclone
Index (TCI). It is a summation of the MSW for each 6-hourly data
point, divided by 100 (kts) with the resultant quotient then squared.
Thus, it is identical to Dr. Bill Gray's Hurricane Destruction Potential
(HDP) except that I begin the TCI with 34 kts, whereas the HDP
calculation begins with 64 kts. It is also very similar to the index
which NOAA uses in their Atlantic seasonal forecasts--a summation
of the square of the velocity--except that I've scaled the TCI
to a baseline of 100 kts in order to avoid huge numbers.
My reason for including the TCI is that it is independent of the
period of data covered. The NTC is a good indicator of overall
tropical cyclone activity, but it changes for all years whenever
a new baseline period is utilized, whether this is done on a yearly
basis or every 5 or 10 years. Thus, for example, 1950's NTC for
the 1950-1990 period is not the same as it is for the 1950-2000
period, etc. The TCI correlates very closely with the NTC, however.
I calculated correlation coefficients for the NTC vs TCI data sets
for several basins, and the two indices always correlated to around
97-98%. Thus, the TCI is an absolute index independent of the average
values of the various parameters, yet it correlates well with the NTC
as computed by Dr. Gray's rule.
C. Southern Hemisphere Basins
-----------------------------
Dividing up the Southern Hemisphere tropical cyclogenetical
regions is rather problematic. The Northern Hemisphere basins are
rather neatly divided geographically by landmasses and regions of
very infrequent tropical cyclone formation, but storms form in
the Southern Hemisphere in a rather continuous band from the
Mozambique Channel off the eastern coast of Africa eastward across
the South Indian Ocean, through the seas and gulfs north of
Australia, into the Coral Sea and across the South Pacific to the
region of French Polynesia well east of the International Dateline.
Several different schemes for dividing the Southern Hemisphere into
useful basins for statistical purposes have been proposed, but none
are completely satisfactory in all respects. For my purposes, I am
going to present statistics for various longitudinal regions, some
of which overlap.
This monthly feature includes a table for the entire Southern
Hemisphere, and then focuses on the South Indian Ocean. Future
monthly features in this series will focus on the South Pacific Ocean
and the Australian Region. I contemplated including data for the
2002-2003 season based on the operational tracks, but in the interest
of getting the summary out in a timely fashion I did not attempt this.
I did glean the numbers of NS, H and IH for the various areas, and
these are summarized following each table. The four regions covered
this month are:
(1) Entire Southern Hemisphere
(2) South Indian Ocean west of longitude 135E
(3) South Indian Ocean west of longitude 105E
(4) Southwest Indian Ocean (west of longitude 90E)
It seemed appropriate to include a table for the entire Southern
Hemisphere, even though it is far too broad an area to consider as a
single basin for most tropical cyclone statistical analyses. The
rationale for Region (2) is that longitude 135E neatly bisects Australia,
the principal landmass in the middle of the Southern Hemisphere tropical
cyclogenetical region. The area around 135E does experience a rather
low-frequency of tropical cyclone formations. Region (3) was included
since it represents the "open" South Indian Ocean. The landmass of
Java extends westward to 105E just north of latitude 10S. However,
west of 105E the island of Sumatra quickly bends away to the northwest,
leaving the basin with open ocean all the way to the equator (and beyond)
west of around 100E. Region (4) lies west of the "political" boundary
between the regions of warning responsibility of Australia versus Meteo
France on La Reunion and Mauritius. There is little reason,
meteorologically speaking, to justify using this meridian as a boundary;
in fact, the area around 90E in some recent seasons has been a local
"hotspot" for the genesis of tropical cyclones.
D. Tables of Tropical Cyclone Data
----------------------------------
The tropical cyclone data in tabular format follows. The various
intensity categories are based on a MSW averaged over 1-minute. This
results in slightly higher numbers of cyclones than would be obtained
utilizing a 10-minute averaging period, as all the Southern Hemisphere
TCWCs do. The year listed in the leftmost column is the year in
which the season ends; e.g., 1961 represents the 12-month period from
1 July 1960 through 30 June 1961.
(1) ENTIRE SOUTHERN HEMISPHERE
Year NS H IH NSD HD IHD NTC TCI
---------------------------------------------------------------
1961 18 6 2 96.25 22.00 2.50 50 106
1962 22 6 0 99.50 10.50 .00 37 83
1963 35 9 2 134.75 24.25 .75 66 141
1964 26 11 1 133.50 32.00 1.25 64 152
1965 27 7 0 87.75 8.50 .00 39 72
1966 19 7 1 80.25 25.50 1.00 45 105
1967 23 8 1 92.25 15.75 1.75 48 95
1968 25 13 2 127.75 36.00 2.25 72 162
1969 24 7 0 87.75 12.00 .00 38 84
1970 30 14 2 149.50 37.50 10.25 95 200
1971 28 15 3 160.25 38.00 2.25 85 195
1972 31 19 7 158.50 50.25 11.00 127 232
1973 34 18 3 145.75 47.50 2.50 95 201
1974 32 11 0 136.25 23.25 .00 59 135
1975 32 10 5 143.50 37.00 9.50 99 193
1976 26 12 3 135.75 37.25 5.00 82 177
1977 29 12 2 132.75 29.25 1.50 70 145
1978 30 13 4 151.50 43.25 5.25 94 194
1979 27 9 6 149.25 42.75 9.75 102 208
1980 28 16 10 174.75 52.75 15.75 144 285
1981 31 14 8 139.00 47.50 10.75 120 208
1982 31 15 7 156.50 52.50 9.25 119 227
1983 26 16 5 132.25 46.75 6.00 99 200
1984 34 17 5 149.00 44.75 9.00 112 230
1985 36 19 10 171.50 50.50 10.50 141 253
1986 33 18 7 147.25 54.25 10.00 125 227
1987 28 14 4 132.50 25.50 2.00 78 143
1988 20 12 4 103.75 25.00 7.50 78 145
1989 34 18 10 164.50 64.50 17.25 156 287
1990 26 18 5 145.00 54.50 11.75 117 230
1991 19 10 4 102.00 34.00 8.25 79 164
1992 30 16 11 147.50 74.75 25.50 173 322
1993 29 12 7 134.25 48.25 14.00 119 227
1994 29 18 11 163.50 71.75 23.25 171 319
1995 21 13 8 102.00 38.25 10.75 104 168
1996 27 15 8 122.50 48.25 17.25 130 232
1997 38 22 8 232.50 72.25 21.50 177 358
1998 36 17 7 157.75 49.50 12.00 129 250
1999 34 13 7 125.25 40.75 14.25 119 207
2000 28 16 8 135.75 53.50 14.50 130 227
2001 22 11 4 77.50 31.75 6.00 74 128
2002 25 12 8 98.75 40.50 17.00 118 196
Avg. 28.2 13.3 5.0 133.8 40.4 8.6
2002-2003 Season - NS: 32 H: 18 IH: 11
(2) ENTIRE SOUTH INDIAN OCEAN (WEST OF 135E)
Year NS H IH NSD HD IHD NTC TCI
---------------------------------------------------------------
1961 9 5 2 53.50 19.00 2.50 56 74
1962 15 5 0 73.00 9.75 .00 43 64
1963 18 7 2 72.75 18.25 .75 67 91
1964 16 7 1 64.25 16.00 1.25 58 77
1965 19 4 0 54.75 5.25 .00 39 44
1966 17 6 1 58.50 15.75 1.00 55 69
1967 15 6 0 52.50 9.75 .00 41 52
1968 19 10 2 100.50 33.50 2.25 92 136
1969 14 5 0 48.75 8.25 .00 37 48
1970 17 11 2 109.50 33.50 10.25 116 165
1971 21 14 3 123.75 37.00 2.25 113 165
1972 15 8 2 76.50 19.50 2.00 71 98
1973 21 14 2 104.00 39.50 1.75 105 153
1974 17 8 0 86.75 16.50 .00 58 91
1975 20 6 3 81.50 19.75 4.75 85 108
1976 14 7 3 85.50 22.75 5.00 85 114
1977 14 8 1 92.50 21.00 .75 66 105
1978 19 9 4 94.50 29.25 5.25 105 135
1979 16 5 4 84.00 26.25 5.50 91 124
1980 17 12 9 128.50 46.00 15.25 177 235
1981 22 10 8 108.00 41.25 10.75 154 175
1982 24 9 2 114.25 36.00 6.25 110 161
1983 11 6 0 37.00 6.50 .00 32 40
1984 25 11 3 114.50 39.25 7.25 125 175
1985 21 12 5 115.50 32.00 4.75 122 162
1986 23 12 7 109.25 43.00 10.00 153 182
1987 13 6 2 69.25 12.00 1.50 58 71
1988 13 7 2 63.50 15.00 4.50 69 85
1989 20 12 6 99.75 42.75 10.50 145 177
1990 20 13 4 109.75 43.50 8.25 133 179
1991 15 7 2 75.00 23.75 4.00 77 115
1992 15 7 7 69.75 36.25 15.50 140 158
1993 16 4 2 62.25 15.50 4.50 66 88
1994 23 14 7 125.25 50.75 14.50 177 232
1995 15 10 7 82.00 33.75 9.75 130 142
1996 20 12 7 93.25 43.50 16.00 164 201
1997 22 13 5 137.50 42.00 13.50 159 212
1998 17 5 2 55.00 11.50 1.75 57 64
1999 22 10 6 82.25 28.50 12.50 137 148
2000 20 12 7 112.25 48.00 14.00 165 200
2001 16 9 4 58.00 26.50 6.00 95 103
2002 17 10 7 82.50 35.75 16.00 151 176
Avg. 17.7 8.8 3.4 86.2 27.5 6.0
2002-2003 Season - NS: 20 H: 11 IH: 5
(3) "OPEN" SOUTH INDIAN OCEAN (WEST OF 105E)
Year NS H IH NSD HD IHD NTC TCI
---------------------------------------------------------------
1961 4 1 0 15.25 2.75 .00 13 13
1962 13 5 0 44.75 9.75 .00 48 43
1963 12 6 1 47.25 16.75 .50 64 66
1964 13 5 1 49.25 11.75 1.25 62 59
1965 13 2 0 33.50 2.25 .00 31 25
1966 12 5 1 42.25 13.00 1.00 59 54
1967 12 4 0 40.00 6.00 .00 40 38
1968 16 10 2 87.25 33.50 2.25 116 127
1969 10 5 0 39.75 8.25 .00 42 43
1970 14 9 2 91.25 30.75 10.25 139 146
1971 15 11 2 96.75 31.50 .75 113 130
1972 12 6 1 62.50 13.25 1.25 68 73
1973 16 10 1 81.00 27.75 1.50 100 114
1974 10 3 0 50.25 7.25 .00 38 49
1975 14 3 0 49.50 9.00 .00 44 49
1976 9 4 1 55.25 11.75 .75 54 59
1977 10 4 1 74.75 14.75 .75 63 82
1978 16 7 3 74.00 21.00 2.50 103 98
1979 14 4 4 75.00 25.00 5.50 114 115
1980 14 9 6 103.75 35.50 11.25 178 181
1981 20 8 5 76.25 22.25 4.50 134 102
1982 14 7 2 80.00 33.00 6.25 118 130
1983 8 4 0 25.75 4.25 .00 30 27
1984 19 8 3 94.75 32.50 7.25 141 148
1985 16 9 3 80.25 17.25 4.00 113 103
1986 17 8 5 80.75 32.50 8.00 152 138
1987 9 3 0 49.00 7.00 .00 36 43
1988 13 7 2 63.50 15.00 4.50 92 85
1989 16 8 4 79.00 32.00 7.75 142 133
1990 17 10 4 92.25 35.25 7.75 154 154
1991 11 6 2 55.00 20.25 4.00 87 90
1992 13 5 5 55.75 27.75 10.75 139 121
1993 13 4 2 50.50 15.50 4.50 82 80
1994 18 12 6 104.25 43.75 13.50 206 204
1995 12 7 4 68.00 26.25 7.25 125 112
1996 13 8 4 64.25 30.75 12.50 151 146
1997 18 11 5 111.00 38.50 13.50 194 185
1998 13 3 1 39.00 5.00 1.00 48 38
1999 16 5 2 55.25 16.75 5.75 95 83
2000 16 8 5 85.00 38.50 11.00 168 153
2001 10 7 3 42.00 23.50 5.00 99 84
2002 15 9 6 73.50 32.75 14.25 180 159
Avg. 13.5 6.4 2.4 65.2 21.0 4.6
2002-2003 Season - NS: 15 H: 10 IH: 4
(4) SOUTHWEST INDIAN OCEAN (WEST OF 90E)
Year NS H IH NSD HD IHD NTC TCI
---------------------------------------------------------------
1961 4 1 0 15.25 2.75 .00 15 13
1962 11 5 0 42.50 9.75 .00 51 42
1963 11 6 1 44.50 16.75 .50 71 65
1964 11 4 1 45.00 11.50 1.25 64 56
1965 12 2 0 32.50 2.25 .00 34 24
1966 12 5 1 34.50 13.00 1.00 66 49
1967 11 4 0 35.00 6.00 .00 43 35
1968 15 9 2 80.25 30.50 2.25 124 117
1969 9 5 0 38.75 8.25 .00 46 42
1970 14 9 2 90.25 30.75 10.25 159 146
1971 14 11 2 94.00 31.50 .75 127 129
1972 11 6 1 55.00 13.00 1.25 74 67
1973 13 8 1 72.00 23.75 1.50 99 100
1974 7 1 0 32.50 6.00 .00 28 32
1975 9 3 0 30.50 9.00 .00 38 33
1976 8 3 1 49.00 10.00 .75 55 52
1977 10 4 1 68.75 14.75 .75 70 77
1978 16 7 2 65.00 14.50 2.00 100 77
1979 13 4 4 62.75 24.50 5.50 125 105
1980 12 6 5 84.25 25.50 7.75 154 136
1981 13 5 3 58.75 16.00 2.75 100 72
1982 12 7 2 70.00 32.00 6.25 129 121
1983 7 4 0 20.75 3.75 .00 31 22
1984 16 7 3 82.50 30.00 7.25 148 133
1985 12 5 2 58.25 12.25 3.50 90 75
1986 14 8 5 69.50 29.50 8.00 163 124
1987 8 3 0 45.50 7.00 .00 40 41
1988 11 6 2 56.25 13.25 4.50 96 77
1989 13 8 4 67.25 32.00 7.75 154 123
1990 11 8 3 71.00 31.00 4.75 131 121
1991 9 5 1 44.75 17.00 2.25 73 73
1992 12 4 4 37.75 17.50 8.50 122 83
1993 13 4 2 48.00 15.50 4.50 93 78
1994 15 11 6 96.75 39.25 13.50 221 189
1995 12 7 4 68.00 26.25 7.25 143 112
1996 11 8 4 53.50 28.50 12.50 164 135
1997 17 10 4 92.25 30.75 11.25 187 151
1998 11 2 1 35.50 4.50 1.00 48 34
1999 11 3 2 32.75 9.00 3.50 72 47
2000 11 6 3 65.00 28.00 6.25 127 107
2001 9 6 3 37.25 20.00 5.00 104 75
2002 13 9 6 62.75 31.75 14.25 198 150
Avg. 11.5 5.7 2.1 55.9 18.5 4.1
2002-2003 Season - NS: 14 H: 9 IH: 3
E. Monthly Tropical Cyclone Information
---------------------------------------
I did not have the time to attempt to ferret out monthly information
regarding tropical cyclone genesis. Patrick Hoareau has already
compiled much information on Southern Hemisphere tropical cyclones,
including monthly tropical cyclone frequencies, and this can be accessed
at the following link:
http://australiasevereweather.com/cyclones/stats.htm>
I would encourage those interested in detailed statistics of Southern
Hemisphere tropical cyclones to visit the above website. More infor-
mation describing Patrick's work can be found in the monthly feature
in the February, 2003, summary.
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for November: No tropical cyclones
Atlantic Tropical Activity for November
---------------------------------------
No tropical storms or depressions formed in the Atlantic basin during
November, but there were a few systems which should be mentioned. A non-
tropical LOW moved across Florida into the Gulf of Mexico during the
opening days of November. This system at times exhibited some features
of subtropical LOWs, and it was thought at one point that it might
undergo some development in the Gulf, but this never materialized. More
information on this system can be found in the October summary.
A tropical wave moved into the eastern Caribbean Sea around the 9th
of November. A broad area of low pressure formed and moved very, very
slowly northward across Puerto Rico and the eastern Dominican Republic
for the better part of a week. Convection at times became slightly
better organized, but the system was never able to form a well-defined
surface circulation. This system brought very heavy rains to the islands
of the northeastern Caribbean. As of early on 15 November some areas in
Puerto Rico had already recorded over 600 mm of rain during the previous
5 days with La Plata measuring almost one metre.
The associated flooding and landslides were quite destructive in
Puerto Rico and the Dominican Republic. Press reports indicated that
at least two persons died in Puerto Rico and ten in the Dominican
Republic while monetary losses amounted to many millions of dollars.
The following links contain some articles related to the aftermath
of the severe flooding:
http://www.caribbeannetnews.com/2003/11/16/floods.htm>
http://www.caribbeannetnews.com/2003/11/23/disaster.htm>
http://www.reliefweb.int/w/rwb.nsf/vLND>
Finally, showers began to increase over the southwestern Caribbean
during the final days of November. The official Atlantic hurricane
season ended on 30 November without any system developing, but the
disturbed weather persisted and began to show signs of organization
during the early days of December. On 4 December the system became
Tropical Storm Odette--the first Atlantic tropical cyclone to form
in December in 19 years and the first December storm on record to
develop within the confines of the Caribbean Sea.
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for November: No tropical cyclones
Northeast Pacific Tropical Activity for November
------------------------------------------------
No tropical cyclones formed in the Northeast Pacific basin during
November, but one tropical disturbance almost developed into a tropical
depression. A system first noted south of Guatemala in late October
slowly moved westward over the next week. By 6 November it was located
about 650 nm southwest of Cabo San Lucas and displayed a fairly well-
organized circulation, but associated convective activity was weak.
The system looked a little healthier the next day and the Tropical
Weather Outlooks issued by TPC/NHC noted that a tropical depression
could form within the next couple of days. The Dvorak rating from
SAB reached T2.0/2.0 at 07/1200 UTC and was up to T2.5/2.5 six hours
later. However, the system encountered hostile upper-level conditions
early on the 8th and quickly weakened.
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for November: 1 tropical depression **
1 typhoon
1 super typhoon
** - classified as a tropical depression by JMA only
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). Also, Huang Chunliang of Fuzhou City, China,
sends me each month tracks obtained from warnings issued by the
National Meteorological Center of China (NMCC), the Central Weather
Bureau of Taiwan (CWBT) and the Hong Kong Observatory (HKO). A very
special thanks to Michael and Chunliang for the assistance they so
reliably provide.
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 November
------------------------------------------------
Tropical cyclone activity during November in the Northwest Pacific
basin was about normal. Two storms were named, and both became typhoons.
Tropical Storm Nepartak moved rapidly through the central Philippines
into the South China Sea, where it intensified into a typhoon and took
aim on Hainan Dao. The storm brushed the western side of the island, but
quickly fell apart before making landfall in southern China. Typhoon
Lupit became an intense super typhoon, but fortunately recurved well
east of the Philippines and did not significantly affect any land areas.
Reports on Nepartak and Lupit follow. (A special thanks to Kevin Boyle
for writing the summary on Nepartak.)
One other tropical weather system was classified as a weak tropical
depression by JMA only on 14-16 November. This system remained quasi-
stationary several hundred miles southwest of Wake Island. Maximum
winds (per JMA) were estimated at 25 kts or less. No track was given
for this system in the accompanying cyclone tracks file. JTWC assigned
this disturbance a fair potential for development at one point, but no
TCFA was issued. Additionally, as the month of November opened, Typhoon
Melor was crossing northeastern Luzon, subsequently weakening and
recurving just east of Taiwan. The complete report on Melor can be
found in the October summary.
TYPHOON NEPARTAK
(TC-25W / TY 0320 / WENG)
10 - 19 November
---------------------------------------------
Nepartak: contributed by Micronesia, is the name of a famous, legendary
Kosrae warrior
Weng: PAGASA name, is a Filipino female nickname for Rowena
A. Storm Origins
----------------
At 0000 UTC on 11 November, animated multi-spectral imagery revealed
a broad area of deep convection associated with an elongated trough.
This convection had persisted for the previous 24 hours approximately
350 nm south-southeast of Guam, and was located in a weak vertical shear
environment with weak to moderate divergence aloft. Development
potential in the STWO issued by JTWC at this time was assessed as poor.
In the 11/1130 UTC STWO the development potential was upgraded to fair,
based on an increase in convection and a better organised LLCC. A TCFA
was released at 11/2030 UTC after spiral banding began to appear over
the system. The first warning on Tropical Depression 25W was issued at
12/1200 UTC with the centre located approximately 775 nm east of Manila,
Philippines. Its position in the southwestern quadrant of an upper-
level anticyclone allowed significant intensification, and at 12/1800
UTC the system was upgraded to a 40-kt tropical storm.
(Editor's Note: JMA initiated bulletins on the pre-Nepartak system as
a 30-kt tropical depression at 1800 UTC on 10 November.)
B. Storm History
----------------
At 0000 UTC on 13 November, the yet-to-be-named tropical storm was
moving smartly westward at 21 kts, located approximately 530 nm east-
southeast of Manila, Philippines. At this time, animated enhanced
infrared satellite imagery and QuikScat data revealed that much of the
deep convection and strongest winds were situated in the northern
quadrant. Increased poleward outflow and the development of deep
convection in the southwestern quadrant coincided with JMA's upgrade to
tropical storm intensity and subsequent naming of the system. Tropical
Storm Nepartak (named Weng by PAGASA) intensified as it tracked quickly
westward through the central Philippines during the 14th and reached
typhoon intensity at 14/1200 UTC, although it was briefly downgraded to
a tropical storm at 14/1800 UTC. But Nepartak/Weng was upgraded again
at 15/0000 UTC as it entered the South China Sea, having successfully
negotiated the Philippines.
After its passage across the Philippines Nepartak slowed somewhat
(to 12 kts) and turned abruptly to the northwest at 15/0600 UTC at a
point approximately 245 nm west of Manila. The heading subsequently
turned back to the west-northwest, and the MSW remained at 65 kts
throughout the 15th. Intensification resumed and Nepartak reached its
first peak intensity at 16/0000 UTC, developing weak duel upper-level
outflow channels as seen on enhanced infrared satellite animations.
Nepartak remained a 75-kt typhoon for the rest of the 16th as it moved
closer to Hainan.
At 0000 UTC on the 17th Typhoon Nepartak was centred approximately
140 nm south-southeast of Hainan Island and closing. Deep convection
had decreased markedly as the system began to entrain drier air into its
circulation. The MSW fell slowly during the 17th but Nepartak held on
to typhoon status, moving to within 80 nm south of Hainan at 17/1200
UTC. A passing shortwave trough dug into the mid-level ridge controlling
Nepartak, resulting in a change to a north-northwesterly heading. Also,
the trough enhanced Nepartak's poleward outflow, and as a result the
MSW re-intensified to a secondary peak of 75 kts at 18/0000 UTC. At
this time, a 10-nm eye feature was observed on a 17/2255 UTC SSM/I pass.
Nepartak's small eye was centred 15 nm south of southwestern Hainan at
18/0000 UTC. Satellite images showed the small typhoon encompassing the
Gulf of Tonkin and Hainan at this time. Movement was toward the north-
northwest at 6 kts, and this took Nepartak's eye as close as 5 nm off
Hainan's western coastline at 18/0600 UTC and 18/1200 UTC. Typhoon
Nepartak deteriorated rapidly soon after its secondary peak and by
18/1800 UTC was basically a swirl of low clouds with little convection.
The downgrade to tropical storm intensity had occurred at 18/1200 UTC
with a further downgrade to tropical depression status at 0600 UTC the
next day. JTWC issued its final warning at 19/1200 UTC after Nepartak's
slow northeasterly motion had taken it inland just west of Beihai, China,
at 19/0900 UTC. Synoptic reports at the time of landfall suggested a
very insignificant system with a MSW of only 20 kts.
(Editor's Note: JMA classified Nepartak as a minimal typhoon for only
one 6-hour period, beginning at 16/1800 UTC. HKO treated the cyclone
as a 60-kt tropical storm at this juncture, but upgraded it to 65 kts
for a 12-hour period on 18 November. NMCC upgraded Nepartak to typhoon
status at 17/0000 UTC and downgraded it at 1200 UTC on the 18th with a
peak 10-min avg MSW of 70 kts at 18/0000 UTC. The minimum CP estimated
by JMA was 975 hPa.)
C. Damage and Casualties
------------------------
Nepartak/Weng caused four deaths and one injury as it moved through
the central Philippines on 14 November. The storm left four million
people without electricity in the provinces of Samar, Leyte and Masbate
and on the nearby island of Marinduque. Schools were closed in Manila
and in nearby provinces due to heavy rain. Rough seas forced the
cancellation of ferry services, leaving 2000 passengers stranded. Only
light damage to crops and houses was reported. No reports of damage or
casualties from Hainan Dao have been received.
(Report written by Kevin Boyle)
SUPER TYPHOON LUPIT
(TC-26W / TY 0321 / YOYOY)
15 November - 6 December
----------------------------------------------
Lupit: contributed by the Philippines, means 'cruel' or 'vicious'
Yoyoy: PAGASA name, is a Filipino male nickname
A. Storm Origins
----------------
JTWC issued an interim STWO at 0900 UTC on 15 November, noting that
an area of convection had developed and persisted for 12 hours roughly
410 nm north-northeast of Kwajalein Atoll in the Marshall Islands.
Cycling convection was present over a weak LLCC, and a 200-mb analysis
indicated weak to moderate outflow and moderate vertical shear. The
maximum surface winds were estimated at 15-20 kts. The potential for
development into a tropical cyclone was assessed as poor. A few hours
later, at 1200 UTC, JMA classified the system as a tropical depression
with 30-kt winds in their High Seas Bulletins. Over the next couple
of days the disturbance drifted slowly westward or southwestward with
little change in organization. A weak LLCC was evident northwest of
the deepest convection. JMA downgraded the system to weak depression
status (winds 25 kts or less) at 16/1200 UTC.
At 2100 UTC on 17 November, the system was located approximately
150 nm northwest of Kwajalein. Cycling deep convection was located over
the LLCC, and a recent QuikScat pass indicated that the circulation had
strengthened some over the past 12 hours. Therefore, the development
potential was upgraded to fair. However, subsequent animated infrared
and water vapor imagery indicated that the deep convection was
dissipating due to convergence associated with an upper-level ridge to
the northwest, so the potential for development was downgraded to poor
at 18/0600 UTC. (At 18/0000 UTC JMA had lowered the system's status
to a low-pressure area and relocated the weak center about 200 nm to
the south of their 17/1800 UTC position.)
As the 18th wore on, deep convection began to re-fire over the LLCC,
and an 18/0655 UTC QuikScat pass indicated that the LLCC had strengthened
once again. Water vapor imagery also revealed an outflow channel to the
east-northeast. JTWC upgraded the development potential to fair once
more at 1000 UTC, and JMA upped the winds back to 30 kts at 1200 UTC.
JTWC issued a TCFA at 1700 UTC, placing the center about 375 nm east-
northeast of Pohnpei. A 200-mb analysis indicated good diffluence
aloft with weak vertical shear, and the MSW was estimated at 20-25 kts.
Visible imagery early on the 19th indicated multiple LLCCs, and the deep
convection continued to cycle in intensity. JTWC issued a second TCFA
at 1700 UTC, and the first warning on Tropical Depression 26W followed
at 2100 UTC. The system was centered approximately 250 nm east-
northeast of Pohnpei, moving west-southwestward at 7 kts as it was being
steered by a mid-level ridge located to the north-northwest. JTWC's
initial warning intensity was 25 kts, although some CI estimates were
already at 30 and 35 kts.
B. Storm History
----------------
TD-26W moved slowly westward or west-southwestward on 20 November.
At 1800 UTC JTWC upgraded the system to tropical storm status with the
center located approximately 180 nm northeast of Pohnpei. Deep
convection had increased but was located mostly to the south of the LLCC.
As the low to mid-level ridge to the north-northwest built on the 21st,
the cyclone's westerly motion increased to around 15 kts. The intensity
remained static for most of the day, but by 1800 UTC satellite CI
estimates had increased to 45 kts, so the MSW was raised to that value.
(NMCC and JMA had upgraded the system to tropical storm status at
21/1200 UTC with JMA assigning the name Lupit.) At 1800 UTC the center
of Tropical Storm Lupit was located approximately 235 nm east-northeast
of Chuuk. Deep convection had increased and the outflow had improved
in all quadrants. Microwave data around 22/0000 UTC depicted a banding
eye feature, and with CI estimates of 55 and 65 kts, JTWC upped the MSW
to 60 kts. A 22/0404 UTC TRMM pass indicated a 16-nm irregular eye,
so Lupit was upgraded to a typhoon at 0600 UTC. (JMA and NMCC did not
upgrade Lupit to typhoon status until 23/1200 UTC and 24/0000 UTC,
respectively.) By 1800 UTC Lupit had reached a position about 360 nm
southeast of Guam, still tracking westward at 16 kts. The intensity as
reported by JTWC had continued to increase and had reached 75 kts by
that time.
Early on the 23rd of November Typhoon Lupit's track shifted to the
west-southwest, moving south of the 8th parallel at 0600 UTC. By 1200
UTC, however, the westward motion had resumed. Satellite imagery at
1200 UTC revealed a small, cloud-filled eye. JMA upgraded Lupit to
typhoon status, and JTWC upped the MSW to 95 kts, where it remained
pegged for 30 hours. By 1800 UTC Lupit was passing about 320 nm south of
Guam. A peripheral ridge building to the southeast of the typhoon began
to modify the steering ridge, causing it to become oriented northeast-
southwest. This was expected to influence Lupit's motion, causing it to
become northwesterly, and this turn to the northwest had occurred by
0600 UTC on 24 November. The eye's appearance was somewhat transient
through much of the 24th and the intensity remained at 95 kts. However,
by 1800 UTC convection had increased and the eye was becoming apparent
again. With CI estimates of 90 and 102 kts, JTWC raised the MSW to
100 kts at 1800 UTC. Typhoon Lupit was just then crossing the 10th
parallel, being located approximately 285 nm southwest of Guam. The
storm continued on a northwesterly trajectory at 12 kts through much of
the 25th, but by 1800 UTC Lupit was moving west-northwestward at 7 kts.
The typhoon was then centered about 170 nm north-northwest of Yap. The
satellite signature fluctuated some throughout the day, but the general
trend was one of intensification with the MSW reaching 120 kts at 1800
UTC. A 25/1742 UTC TRMM pass depicted a 15-nm diameter eye.
Lupit's 66-hour reign as a super typhoon (the year's fifth) began at
0000 UTC on 26 November when JTWC upped the MSW to 130 kts. The intense
storm was then centered approximately 200 nm north-northwest of Yap.
With good outflow channels in both poleward and equatorward directions,
Lupit continued to slowly intensify. The cyclone was still being steered
by a mid to upper-level ridge situated to the northeast, but the ridge
was being weakened by a series of shortwave troughs propagating east-
ward from Asia. Hence, the typhoon's motion became more northwesterly.
The slow northwestward motion continued on the 27th as Super Typhoon
Lupit reached its estimated peak intensity of 145 kts, based on CI
estimates of 140 and 155 kts. At 27/0000 UTC the 14-nm eye was centered
approximately 730 nm south-southwest of the island of Iwo Jima. Storm-
force winds extended outward 80-100 nm from the center, and gales
covered an area well over 400 nm in diameter. The minimum CP estimated
by JMA was 915 hPa. (The peak 10-min avg MSW estimates from JMA, PAGASA
and NMCC were 100 kts, 110 kts and 120 kts, respectively.)
The 28th of November saw Super Typhoon Lupit begin to track increas-
ingly toward the north-northwest into a weakness in the subtropical
ridge. The storm had undergone an eyewall replacement cycle late on the
27th, and subsequently began to show signs of weakening: weakening
eyewall convection, warmer eye temperatures, and a decrease in outflow.
JTWC maintained the MSW at 140 kts on the 1200 UTC warning, but dropped
the intensity to 125 kts at 1800 UTC. (Interestingly, CI estimates at
the time were ranging from 102 to 140 kts.) At 0000 UTC on 29 November
Typhoon Lupit was centered about 520 nm south-southeast of Okinawa. The
storm was tracking north-northwestward at 8 kts, but by 1200 UTC the
heading had become northerly, and by 1800 UTC Lupit had crossed the
subtropical ridge axis and was moving northeastward. The typhoon was
entering a more hostile vertical shear environment and CI estimates
gradually fell through the 29th--by 1800 UTC the MSW was down to 95 kts.
At 0000 UTC on 30 November Typhoon Lupit, with 90-kt winds, was
centered approximately 375 nm southeast of Okinawa, moving to the north-
east at 12 kts. The storm's forward motion accelerated considerably as
the 30th progressed: by 1800 UTC Lupit was speeding northeastward at
24 kts as it became increasingly involved with the mid-latitude
westerlies. Satellite imagery revealed a significant decrease in
convection as dry air began to be entrained into the system, and this,
along with increasing vertical shear, contributed to the continued
weakening of Lupit. JTWC downgraded Lupit to a 60-kt tropical storm at
0000 UTC on 1 December. (JMA and NMCC were still maintaining the cyclone
as a typhoon, but downgraded it six hours later.) The storm was located
about 200 nm northwest of Iwo Jima, embedded in an unfavorable environ-
ment and weakening rapidly. JTWC issued the final warning on Lupit
at 01/0600 UTC with the storm located 270 nm north-northwest of Iwo Jima
and racing northeastward at 26 kts. The storm was beginning to undergo
extratropical transition; however, JMA continued issuing tropical cyclone
bulletins on Lupit through 02/0600 UTC, declaring the storm extratropical
at 02/1200 UTC. The remnants of the former super typhoon continued
northeastward, turning to the north on the 3rd of December. Based on
ship reports, the system remained a vigorous 50-kt storm through the
5th, but then weakened rapidly. By 0600 UTC on 6 December all that
remained was a 25-kt LOW east of the Kamchatka Peninsula.
C. Meteorological Observations
------------------------------
The Japanese island of Chichijima (WMO 47971, 27.1N, 142.2E, Alt 3 m)
reported a gust of 61 kts at 0138 UTC on 1 December. A higher gust of
72 kts was recorded a couple hours later at 01/0340 UTC. A peak gust
of 70 kts was reported from Hachijojima (time unknown). (Thanks to
Huang Chunliang for sending along these observations.)
D. Damage and Casualties
------------------------
No reports of damage or casualties resulting from Super Typhoon Lupit
have been received by the author.
(Report written by Gary Padgett)
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for November: 1 tropical cyclone of hurricane intensity
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.
TROPICAL CYCLONE
(TC-02A)
12 - 15 November
------------------------------------
An area of convection developed on 10 November approximately 600 nm
west of Cochin, India, in the Arabian Sea. The disturbance was located
in a low vertical shear environment with weak to moderate divergence
aloft. A QuikScat pass indicated a possible weak LLCC with winds of
15-20 kts. By 1800 UTC on the 11th the system had reached a position
about 800 nm west of Cochin. Environmental conditions were still rather
favorable for intensification, so JTWC upgraded the development potential
to fair. A TCFA was issued at 12/0500 UTC. Deep convection was located
over the LLCC and vertical shear was weak over the northern half of the
circulation and moderate over the southern half. IMD classified the
system as a depression at 0900 UTC, and JTWC issued the first warning
on Tropical Cyclone 02A at 1200 UTC. The MSW was estimated at 30 kts,
based on CI estimates of 25 and 35 kts, and the center was placed
approximately 650 nm east of the coast of Somalia, tracking west-
southwestward under the influence of a ridge to the north. (IMD upgraded
the system to deep depression status at 12/1800 UTC, implying 30-kt peak
winds.)
The next JTWC warning at 13/0000 UTC upped the MSW to 55 kts. Deep
cycling convection had consolidated over the LLCC, rapidly intensifying
TC-02A into a strong tropical storm. A 13/0650 UTC AMSU pass depicted
a 25-nm eye, and at 1200 UTC the cyclone was upgraded to hurricane
intensity. The storm was then centered about 475 nm east-southeast of
Somalia, moving westward at 6 kts. Satellite CI estimates continued to
increase, reaching 77 kts at 1800 UTC, so the MSW was bumped up to
75 kts. Tropical Cyclone 02A reached its peak intensity of 85 kts at
0000 UTC on 14 November, based on CI estimates of 90 kts. Gales covered
an area roughly 250 nm in diameter while 50-kt winds reached outward
from the center 50-70 nm. The storm didn't maintain its peak for very
long--at 1200 UTC CI estimates had dropped to 55-65 kts and the MSW was
reduced to 65 kts. The cyclone was then located about 335 nm east of the
coast of Somalia, tracking west-southwestward at 9 kts. There had been
a significant decrease in outflow and convection during the previous six
hours, and the rapid weakening trend continued.
The main culprit in the demise of TC-02A appeared to be entrainment
of much dry air into the system. The 14/1800 UTC warning relocated the
center and further reduced the intensity to 50 kts, based on CI estimates
of 45-55 kts. Microwave imagery around 0000 UTC on 15 November revealed
that the system had weak convection west of a completely exposed LLCC.
The MSW was dropped to 40 kts, and JTWC issued their final warning on
TC-02A at 15/0600 UTC. The center of the weakening cyclone was located
approximately 280 nm east of Somalia, moving westward at 6 kts. The
final warning intensity was 30 kts, and the system was forecast to
continue weakening and dissipate completely by the time it reached the
Somalian coast in about 36 hours.
No damage or casualties are known to have resulted from this Arabian
Sea tropical cyclone.
(Report written by Gary Padgett)
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for November: 1 tropical cyclone (hurricane)
Sources of Information
----------------------
The primary sources of tracking and intensity information for
Southwest Indian Ocean tropical cyclones are the warnings issued by
the Tropical Cyclone Warning Centre on La Reunion Island, part of
Meteo France (MFR), and the Regional Specialised Meteorological Centre
for the basin. However, tropical cyclones in this region are named
by the sub-regional warning centres on Mauritius and Madagascar with
longitude 55E being the demarcation line between their respective
areas of warning responsibility. The La Reunion centre only advises
these agencies regarding the intensity of tropical systems. References
to sustained winds imply a 10-minute averaging period unless otherwise
stated.
In the companion tropical cyclone tracks file, I occasionally
annotate positions from warnings issued by the Joint Typhoon Warning
Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
Harbor, Hawaii, when they differ from MFR's coordinates by usually
40-50 nm or more. The JTWC warnings are also the source of the
1-minute average maximum sustained wind values included in the
tracks file. Additionally, information describing details of
satellite imagery and atmospheric circulation features included in
the narratives is often gleaned from the JTWC warnings.
TROPICAL CYCLONE BENI
(MFR-02 / TC-02S)
9 - 22 November
-----------------------------------------
Beni: contributed by Zimbabwe
A. Storm Origins
----------------
What would become the Southwest Indian Ocean's first tropical cyclone
(hurricane) of the season, and also the Southern Hemisphere's first
intense tropical cyclone of the 2003-2004 season, can be traced to an
area of convection which formed approximately 430 nm east-northeast of
Diego Garcia on 7 November. Satellite imagery revealed an area of
broad surface troughing with disorganized and cycling deep convection
in the region. A 200-mb analysis revealed moderate diffluence aloft with
decreasing vertical shear. JTWC upgraded the development potential to
fair at 1300 UTC on the 8th as convection had continued to increase in
organization. A TCFA was issued at 08/2200 UTC, the center then being
located approximately 425 nm east-northeast of Diego Garcia. Deep
convection had increased and appeared to be consolidating into a possible
CDO over the LLCC, outflow was good, and vertical shear was weak. The
maximum surface winds were estimated at 25-30 kts.
The first JTWC warning on Tropical Cyclone 02S was issued at 0600 UTC
on 9 November. (MFR had not yet initiated bulletins on the system.) The
MSW was estimated at 30 kts, and the center of TC-02S was placed about
380 nm east-northeast of Diego Garcia, moving southward at 5 kts. A
low-level ridge to the southeast appeared to be the primary steering
mechanism. TC-02S slowly became better organized on 10 November: spiral
banding became more pronounced and began to wrap into the LLCC. MFR
initiated bulletins on Tropical Disturbance 02 at 0600 UTC, and upgraded
the system to tropical depression status (30 kts) at 1800 UTC. (At
10/0600 UTC JTWC had upped the 1-min avg MSW to 35 kts.) By 1800 UTC
the system was located approximately 170 nm east of Diego Garcia, moving
westward at 5 kts. The depression continued to intensify and by 0600
UTC on 11 November had become Tropical Storm Beni. Satellite CI esti-
mates at the time were ranging from 35 to 55 kts.
B. Storm History
----------------
At 11/1800 UTC Beni was centered about 110 nm east-southeast of Diego
Garcia with the MSW having increased to 40 kts (45 kts per JTWC). The
storm was moving southwestward at 5 kts, thereby lessening the threat
to Diego Garcia. The mid-level ridge to the east which had been the
primary steering mechanism for Beni was weakening, and the storm had
gotten caught in a weak steering environment between that ridge and
one to the west. The storm's heading gradually bent more to the south,
and by 12/1800 UTC Beni was moving south-southeastward at 4 kts. Both
MFR and JTWC were forecasting modest intensification to minimal cyclone
(hurricane) intensity, following by gradual weakening as the system
moved into a higher vertical shear environment. However, a big surprise
was in store! A major shortwave trough passing to the south of the
tropical storm greatly enhanced the poleward outflow, and Beni responded
by intensifying rapidly. JTWC upped the intensity to 70 kts at 1800
UTC, based on CI estimates of 65 and 77 kts. MFR's 1800 UTC intensity
was still 55 kts, but six hours later that agency had bumped the MSW to
75 kts (10-min avg).
Tropical Cyclone Beni reached its peak intensity of 100 kts (105 kts
1-min avg from JTWC) at 0600 UTC on 13 November. The cyclone was then
located approximately 250 nm southeast of Diego Garcia, moving south-
southeastward at 4 kts. The minimum CP estimated by MFR was 935 mb.
Satellite CI estimates were only 77 and 90 kts, but a 13/1041 UTC SSM/I
pass and animated enhanced imagery depicted a 15-nm eye and increased
symmetry to the system. Beni's tenure as an intense tropical cyclone
was short-lived, however. By 13/1800 UTC the strong upper-level flow
which on the previous day had provided excellent outflow was now creating
an unfavorable vertical shear environment. A 13/1444 UTC SSM/I pass
showed that convection had significantly decreased over the previous six
hours and that the LLCC was almost fully-exposed. MFR reduced the MSW
to 85 kts at 1800 UTC and to 60 kts at 14/0000 UTC. (JTWC still reported
the intensity at 100 kts in the 1800 UTC warning, but had reduced it to
50 kts by 14/0600 UTC.) Tropical Storm Beni continued to track slowly
southeastward on the 14th as westerly shear remained fairly strong.
Some deep convection rebuilt near the LLCC, but the storm gradually
weakened. By 1800 UTC MFR had lowered the MSW to 35 kts with the system
located about 500 nm southeast of Diego Garcia.
(Note: I discovered an e-mail from Karl Hoarau after writing the above
paragraph. MFR based their peak 100-kt intensity (10-min avg) on a Data
T-number of 6.0 instead of the T4.5 and T5.0 reported by JTWC in their
13/0600 UTC warning. Karl had performed a Dvorak analysis of Beni and
concurred with MFR's analysis. In fact, in his opinion Data T-numbers
of 6.5 were likely from 0300 to 0500 UTC, so the best value for the
peak 1-min avg MSW for Beni is 115 kts.)
MFR downgraded Beni to a tropical depression at 15/0600 UTC, and six
hour later the system was further downgraded to a tropical disturbance
and the final warning (for the time being) issued. The concurrent JTWC
warning noted that CI estimates were ranging from 30 to 45 kts. JTWC
issued their "final" warning on Beni at 15/1800 UTC, placing the center
about 480 nm southeast of Diego Garcia. Vertical shear had increased
and the convection had decoupled from the LLCC, which was now being
steered southwestward by the low-level flow. For the next couple of
days the residual circulation remained quasi-stationary, or perhaps
drifted very slowly to the west or west-northwest. By the 17th the
system was showing signs of life once more, and MFR re-initiated
bulletins at 1200 UTC. JTWC following with a warning at 1800 UTC.
The center was located around 340 nm southeast of Diego Garcia and
tracking west-northwestward at 5 kts. Deep convection had become more
persistent and was once more co-located with the LLCC, which had
improved in organization as well. The system was forecast to intensify
only slightly before commencing weakening again. But once again, Beni
had a surprise in store.
At 0600 UTC on 18 November MFR upgraded Beni once again to tropical
storm status with 40-kt winds. (JTWC also significantly upped the 1-min
avg MSW estimate from 30 to 55 kts.) Beni was then located approximately
240 nm south-southeast of Diego Garcia, moving west-northwestward at
10 kts. An upper-level anticyclone over the storm was providing
excellent outflow and convection had rapidly developed over the LLCC.
There were also hints of an eye in infrared imagery. MFR increased the
intensity to 60 kts at 1800 UTC, and Beni became a tropical cyclone
(hurricane) once more at 19/1200 UTC with the MSW estimated at 70 kts.
A low-level subtropical ridge building from the west was expected to
keep Beni moving in a generally westerly direction. At 0600 UTC on
the 19th Beni was located 285 nm south of Diego Garcia, and satellite
imagery indicated that the system had a small 12-nm eye. (JTWC upped
the 1-min avg MSW to 65 kts at this point.) At 1800 UTC CI estimates
ranged from 65 to 90 kts, but animated enhanced infrared imagery
indicated that the eye had fallen apart.
By 20/0600 UTC convection associated with Beni was beginning to
decrease. MFR downgraded the cyclone to severe tropical storm status
with 60-kt winds (10-min avg). Twelve hours later Beni was located
approximately 400 nm south-southwest of Diego Garcia, moving west at
11 kts. The system had weakened very rapidly; CI estimates were down
to 30 and 35 kts. MFR dropped the intensity to 40 kts, and downgraded
the system to tropical depression status at 0000 UTC on 21 November.
(JTWC had issued their final warning at 20/1800 UTC.) MFR tracked the
depression westward for another couple of days, issuing the final
bulletin at 22/1200 UTC with the center located approximately 185 nm
southeast of Agalega or about 235 nm north-northwest of St. Brandon.
On 21 November satellite imagery indicated that Beni underwent a
rapid strengthening for a third time, although this was not reflected
in any bulletins from the TCWCs. Several persons in some e-mail
discussion groups commented on this, so I asked Dr. Karl Hoarau to
take a look at imagery of Beni on the date in question. Karl's opinion
was that Beni did regain tropical storm intensity on the 21st, possibly
reaching an intensity of 45-50 kts (1-min avg) at 0600 UTC. After
21/0200 UTC enhanced infrared pictures indicated a dramatic intensi-
fication. Convection with cloud tops of -70 to -75 C built over the
LLCC, and from 0330 to 0530 UTC the LLCC was embedded more than a third
of a degree under a CDO 2.5 degrees in diameter. Data T-numbers were
at 3.5. Following this brief burst of life, shear increased once more
over the system and by 1200 UTC the LLCC was completely exposed one
degree northwest of the convection. Convection fluctuated over the
next 24 hours but the system did not regain tropical storm intensity
again. (A special thanks to Karl for performing this analysis of Beni.)
C. Damage and Casualties
------------------------
No damage or casualties are known to have resulted from Tropical
Cyclone Beni.
(Report written by Gary Padgett)
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for November: No tropical cyclones
*************************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for November: No tropical cyclones
*************************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for November: No tropical cyclones
*************************************************************************
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 July, 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.
*************************************************************************
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, and
Chris Landsea):
http://australiasevereweather.com/cyclones/>
http://www.typhoon2000.ph>
http://mpittweather.com>
ftp:// ftp.aoml.noaa.gov/hrd/pub/landsea/padgett/>
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.met-office.gov.uk/sec2/sec2cyclone/sec2cyclone.html>
TROPICAL CYCLONE REPORTS AVAILABLE
JTWC now has available on its website the complete Annual Tropical
Cyclone Report (ATCR) for 2002 (2001-2002 season for the Southern
Hemisphere). ATCRs for earlier years are available also. The report
for the 2002-2003 Southern Hemisphere season has also recently been
added.
The URL is: http://199.10.200.33/jtwc.html>
Also, TPC/NHC has available on its webpage nice "technicolor"
tracking charts for the 2003 Atlantic and Eastern North Pacific
tropical cyclones; also, storm reports for all the 2003 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 (Eastern Atlantic, Western Northwest Pacific, South
China Sea)
E-mail: [email protected]
Huang Chunliang (Assistance with Western Northwest Pacific, South
China Sea)
E-mail: [email protected]
Simon Clarke (Northeast Australia/Coral Sea, South Pacific)
E-mail: [email protected]
*************************************************************************
*************************************************************************
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Document: summ0311.htm
Updated: 26th October 2006 |
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