[Index]
Monthly Global Tropical Cyclone Summary October 2006
[Summaries and Track Data] [Prepared by Gary Padgett]
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Monthly Global Tropical Cyclone Summary October 2006 [Summaries and Track Data] [Prepared by Gary Padgett] |
MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
OCTOBER, 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of the summaries and found that the entire October track file has been
archived on two of them. The links are:
http://australiasevereweather.com/cyclones/2007/trak0610.htm>
http://www.typhoon2000.ph/garyp_mgtcs/oct06tks.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.)
*************************************************************************
OCTOBER HIGHLIGHTS
--> Atlantic very quiet--no tropical cyclones form
--> Extremely intense super typhoon strikes northern Luzon
--> South Pacific season gets underway early with intense tropical
cyclone
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for October: 1 hurricane **
** - Storm formed in September
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 October
--------------------------------------
Following are some statistics for the Atlantic basin during the month
of October:
October Average
Parameter 2006 1950 - 2005
--------------------------------------------------------
Named Storms (NS) 0 1.7
Hurricanes (H) 0 1.1
Intense Hurricanes (IH) 0 0.4
Named Storm Days (NSD) 2.00 9.3
Hurricane Days (HD) 1.75 4.4
Intense Hurricane Days (IHD) 0 0.8
No tropical cyclones formed in the Atlantic basin during the month
of October, 2006. The only cyclone on the map was Hurricane Isaac on
the first two days of the month. Isaac had formed in late September and
passed well to the east of Bermuda, reaching hurricane intensity at
1200 UTC on 30 September. The storm weakened to a tropical storm just
before clipping southeastern Newfoundland on 2 October, and shortly
thereafter was declared extratropical. The report on Isaac may be found
in the September summary, and the official TPC/NHC report on this cyclone
is now available online.
!!!!!!!!!!!!!!! EXTRA FEATURE !!!!!!!!!!!!!!!
ADDITIONAL ATLANTIC TROPICAL STORM ADDED
As noted in the Extra Feature in the August summary, a low-pressure
system south of Nova Scotia in mid-July exhibited some tropical storm
characteristics and was being considered for inclusion in the official
roster of 2006 tropical cyclones as an unnamed tropical storm. During
the post-season analysis, the decision was made to include this system,
bringing the number of "named" storms for 2006 to ten. The official
TPC/NHC report on this storm, as well as reports for all the Atlantic
storms, may be found at the following URL:
http://www.nhc.noaa.gov/2006atlan.shtml>
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for October: 2 tropical depressions **
2 tropical storms
1 hurricane
** - one of 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 October
-----------------------------------------------
Following are some statistics for the Northeast Pacific basin during
the month of October:
October Average
Parameter 2006 1971 - 2005
--------------------------------------------------------
Named Storms (NS) 3 2.0
Hurricanes (H) 1 1.1
Intense Hurricanes (IH) 0 0.6
Named Storm Days (NSD) 6.50 9.1
Hurricane Days (HD) 1.75 4.1
Intense Hurricane Days (IHD) 0 1.2
The Northeast Pacific basin was somewhat quieter than normal during
October, 2006, with the average level of activity being around 60% of
what is normal for October. Three named storms developed (average is
two) and there was one hurricane, which is the average. However, the
number of NSD and HD was rather lower than normal and there was no
intense hurricane. Tropical Storms Norman and Olivia formed more or
less simultaneously in early October well southwest of Baja California,
but remained weak and were short-lived. Several days after weakening
to a remnant LOW, Norman's remnants interacted with another disturbance
and regained depression status just off the Mexican coast. Hurricane
Paul became a respectable Category 2 hurricane and turned northeastward
toward the southern tip of the Baja Peninsula, but had weakened into a
depression before reaching the Mexican coast. The following reports
on the named cyclones are very brief as the official TPC/NHC reports on
all the Eastern Pacific storms are now available online.
Two additional non-developing tropical depressions also formed during
October. The final in a series of short-lived tropical depressions in
the Central Pacific formed about 650 nm southwest of Honolulu on the
13th and was designated Tropical Depression 04C. Vertical shear
proved too strong for the depression to strengthen and advisories were
discontinued the next day. Further east, Tropical Depression 18E formed
well to the south of Cabo San Lucas on 26 October. However, the
environment was not conducive for tropical cyclone maintenance and this
system met its demise on the 27th.
Short reports with satellite pictures and small-scale maps for all
the Northeast Pacific systems may be found at the following link:
http://en.wikipedia.org/wiki/2006_Pacific_hurricane_season>
The official TPC/NHC storm reports for the Eastern Pacific systems
east of 140W may be found at the following URL:
http://www.nhc.noaa.gov/2006epac.shtml>
TROPICAL STORM NORMAN
(TC-15E)
9 - 15 October
-----------------------------------------
Tropical Storm Norman's origins lay with a tropical wave which emerged
off the African coast around 21 September. The wave marched westward
with little convection, moving into the Eastern North Pacific on
1 October. During the early days of October a large and complex area
of disturbed weather existed southwest of Mexico, and the tropical wave
was involved with the eastern portion of the disturbance. Farther to
the west was located another system which became the next Eastern North
Pacific cyclone, Olivia. Convective organization increased and a
tropical depression had formed by around 0000 UTC on 9 October about
665 nm southwest of Cabo San Lucas on the southern tip of the Baja
California Peninsula. TD-15E moved slowly to the north-northwest and
became a tropical storm around 1200 UTC. After peaking at 45 kts on
10 October, Norman came under increasingly hostile southwesterly shear
which led to its weakening to a tropical depression later on the 10th.
On the 11th Norman weakened into a remnant LOW situated about 460 nm
southwest of Cabo San Lucas.
Over the next few days the remnant LOW moved east-southeastward, then
eastward on 14 October. The system interacted with a broad area of
disturbed weather near the Mexican coast, and during this time convection
re-organized near the center of the LOW, resulting in Norman's being
re-designated as a tropical depression at 15/0000 UTC about 175 nm south-
southeast of Manzanillo. Tropical Depression Norman moved northward and
then northwestward inside the cyclonic envelope of the larger disturbance
and abruptly dissipated late on the 15th just south of Manzanillo.
Conventional satellite imagery suggested that Norman's center may have
moved inland east of Manzanillo, but surface observations did not support
a landfall.
There were no reports of damage or casualties associated with Tropical
Storm Norman.
(Report written by Gary Padgett, based upon the official TPC/NHC report
authored by Jack Beven)
TROPICAL STORM OLIVIA
(TC-16E)
9 - 12 October
-----------------------------------------
Tropical Storm Olivia, which operated concurrently with Tropical Storm
Norman, originated from a tropical wave which had emanated out of western
Africa on 18 September--ahead of the pre-Norman wave. The wave moved
rather uneventfully across the Atlantic and Caribbean with little
associated convection. However, upon reaching the Eastern North Pacific
on 29 September, convection began to slowly increase. The wave continued
westward and by the 5th a broad low-pressure area had formed along the
wave axis. Moderate upper-level westerly shear, however, inhibited
further development for a few days as the LOW continued westward. It is
estimated that a tropical depression had formed by 1800 UTC on 9 October,
centered about 1180 nm west-southwest of Cabo San Lucas. TD-16E moved
slowly northward into a region of weaker vertical wind shear and had
strengthened into Tropical Storm Olivia by 0600 UTC on 10 October.
Shortly after being upgraded, Olivia accelerated northeastward and
reached its peak intensity of 40 kts just six hours later. However, this
northeasterly motion carried the tropical cyclone into a region of strong
upper-level southerly winds and drier air which caused the deep
convection to weaken and shear away from the center. Olivia was down-
graded to a tropical depression at 11/1200 UTC when located about 900 nm
west-southwest of the southern tip of the Baja Peninsula. It then turned
eastward and persistent strong vertical shear led to Olivia degenerating
into a remnant LOW early in the 13th. This LOW moved east-southeastward
and was absorbed into the larger remnant circulation of former Tropical
Storm Norman on 15 October. It is considered possible that the remnants
of Olivia may have played a role in the regeneration of Norman into a
tropical depression off the Mexican coast a few hours later.
There have been no reports of damage or casualties resulting from
Tropical Storm Olivia.
(Report written by Gary Padgett, based upon the official TPC/NHC report
authored by Stacy Stewart.)
HURRICANE PAUL
(TC-17E)
21 - 26 October
-----------------------------------
A tropical wave which emerged from the coast of Africa on 4 October
was the progenitor of Hurricane Paul. As with the tropical waves which
had produced Tropical Storms Norman and Olivia, the pre-Paul wave also
produced little deep convection during its sojourn across the tropical
Atlantic and Caribbean Sea. Crossing Central America on 18 October, the
wave moved into a pre-existing area of disturbed weather over the Eastern
North Pacific on the 19th. This merger resulted in the formation of a
larger area of convection which extended northward to the southern coast
of Mexico. A LOW formed on 20 October and a tropical depression was
estimated to have developed by 0600 UTC on the 21st about 230 nm south-
southwest of Manzanillo, Mexico. TD-17E quickly strengthened and was
upgraded to Tropical Storm Paul only six hours after being classified as
a tropical depression. A mid to upper-tropospheric ridge over Mexico
was producing easterly shear over the cyclone, so Paul did not strengthen
significantly for the next 24 hours.
Late on the 22nd Paul reached the western periphery of the ridge and
the vertical shear decreased. The storm responded by intensifying rather
rapidly--during the 18-hour period from 22/1800 and 23/1200 UTC Paul's
estimated MSW increased from 45 to 90 kts. In addition, the forward
motion decreased as Paul began to turn toward the north. Soon afterward
the hurricane began to interact with a large mid to upper-level trough
off the U. S. West Coast. Paul began to curve onto a northeasterly
track and the increasing westerly shear resulted in weakening beginning
late on the 23rd.
The center of Hurricane Paul passed just west of Socorro Island early
on 24 October and around 24 hours later passed only about 40 nm south
of Cabo San Lucas. The cyclone by this time had been downgraded to a
tropical storm, and further weakening ensued with Paul being further
downgraded to a tropical depression at 26/0000 UTC as it approached the
coast of mainland Mexico. The weak system turned northward and made
landfall along the coast near the southern end of Isla Altamura around
0400 UTC on the 26th, dissipating a few hours later approximately 50 nm
northwest of Culiacan.
Four deaths were directly attributed to Paul in Mexico. Two persons,
including an American tourist, were swept out to sea from the southern
tip of the Baja due to large waves and high surf kicked up by the
weakening cyclone. Even though only a tropical depression at landfall,
Paul produced very heavy rainfall in Mexico, resulting in floods in the
state of Sinaloa. According to media reports, 5000 homes were damaged,
resulting in 20,000 people being displaced. Two deaths occurred in the
municipality of Navolato where a truck was swept away by a swollen river.
(Report written by Gary Padgett, based upon the official TPC/NHC report
written by Jamie Rhome and Robert Berg)
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for October: 3 tropical depressions **
2 tropical storms
1 typhoon
1 super typhoon
** - none of these classified by JTWC; one classified by PAGASA only,
two others classified 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). 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 October
-----------------------------------------------
Tropical activity in the Northwest Pacific basin was fairly normal
in October. Four tropical cyclones were named. Tropical Storms Rumbia
and Bebinca during the opening days of the month were large, loosely-
organized monsoon depression-type tropical storms with Bebinca moving
northward through the Philippine Sea and the concurrent Rumbia moving
northward well east of the Marianas. Typhoon Soulik during the middle
decade of the month formed north of Pohnpei and moved northwestward
toward Iwo Jima, where it stalled and intensified into a typhoon of
moderate intensity before moving northward and recurving into the
westerlies southeast of Japan. Super Typhoon Cimaron was arguably
the most intense Northwest Pacific tropical cyclone of 2006 and the
most intense to strike the typhoon-plagued Philippine Archipelago since
Super Typhoon Zeb in 1998. Fortunately, the storm was rather small in
areal extent and made landfall in an apparently sparsely-populated
region. Reports on all the named cyclones follow.
As the month opened, Typhoon Xangsane was making landfall in Vietnam
and had dissipated by the 2nd. Three systems were classified as tropical
depressions by various warning agencies, though not by JTWC. A slow-
moving low-pressure area in the vicinity of Iwo Jima was classified as
a weak tropical depression by JMA beginning at 0000 UTC on 21 October.
The system was drifting slowly north-northwestward and was downgraded
to a low-pressure area by 1800 UTC the same day. A low-pressure area
in the South China Sea near 16.0N/113.0E was referenced as a weak
tropical depression in JMA's High Seas Bulletin at 0600 UTC on 22 October
but was not mentioned further. The first of these systems was mentioned
in JTWC's STWOs as an area with a 'poor' potential for development; the
second wasn't referenced at all.
Another system was briefly classified as a tropical depression by
PAGASA and named Ompong. Tropical Depression Ompong was in existence
on 12-13 October, remaining quasi-stationary to the east of Luzon.
Maximum winds estimated by PAGASA were 30 kts. However, I could find
no reference to this system in either JMA's bulletins or in JTWC's STWOs,
which suggests that it was likely a broad monsoon LOW with little
organized deep convection. No tracks were given for Ompong nor the
two weak JMA depressions in the companion cyclone tracks file. The
PAGASA track for Tropical Depression Ompong may be found at the
following link:
http://www.typhoon2000.ph/stormarchives/2006/stormlogs/15ompong06_log.htm>
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>
TROPICAL STORM BEBINCA
(TC-19W / TS 0616 / NENENG)
28 September - 6 October
-----------------------------------------------
Bebinca: contributed by Macau, is the name of a Macanese milk pudding
served in the Portuguese restaurants of Macau
A. Introduction and Storm Origins
---------------------------------
Tropical Storm Bebinca, known in the Philippines by the name Neneng,
was a fairly weak tropical storm in early October which formed in the
Philippine Sea and recurved east of Luzon. Bebinca operated concurrently
with Tropical Storm Rumbia farther to the east, and in its extratropical
stages appeared to absorb the latter storm. An area of convection formed
and persisted just east of Guam on 27 September and was referenced in a
STWO issued at 27/1730 UTC. Infrared satellite imagery showed convection
beginning to consolidate near an elongated LLCC, while an upper-level
analysis revealed an anticyclone aloft directly over the disturbance
providing good outflow and low vertical wind shear. JMA identified
the system as a weak tropical depression at 28/1200 UTC in a High Seas
Bulletin, and by the 29th the disturbance was located approximately
165 nm north-northeast of Yap. A TUTT was enhancing divergence aloft,
and Yap had experienced a drop in MSLP of 2.5 mb over the previous 24
hours. Given this, plus the consolidating convection and still-favorable
environment aloft, JTWC upped the development potential to 'fair' at
29/1500 UTC.
The system had entered PAGASA's AOR by 0600 UTC on 1 October and that
agency immediately initiated warnings on Tropical Depression Neneng. Six
hours later JTWC issued their first warning on Tropical Depression 19W,
placing the center about 725 nm south-southeast of Okinawa and moving
northwestward at 18 kts. TD-19W was situated within a broad monsoon
trough located east of the Philippines and was slow to intensify due
to the competing influences of favorable outflow aloft and moderate
vertical shear. By 1800 UTC on 2 October organization had proceeded to
the point that JTWC upgraded TD-19W to tropical storm intensity and
placed the center about 725 nm south of Naha, Okinawa. Six hours later
JMA also upgraded the system to tropical storm status and assigned the
name Bebinca.
B. Synoptic History
-------------------
Bebinca had been essentially stationary well to the east of Luzon
while strengthening to tropical storm intensity, but by 0600 UTC on
3 October a pronounced northward motion had developed. The system was
slow to gain in intensity--JMA upped their MSW estimate to 40 kts at
03/1800 UTC, and JTWC increased their intensity to an initial peak
of 45 kts at 04/0000 UTC. However, Bebinca soon began to experience
shear with a weakening trend setting in. At 04/1800 UTC JTWC downgraded
Bebinca briefly to a tropical depression with the estimated center
located about 450 nm west-southwest of Iwo Jima. Animated infrared
satellite imagery and a 04/1726 UTC AMSU pass depicted two possible
LLCCs within a broad low-pressure area. Surprisingly, just six hours
later Bebinca was re-upgraded with its intensity set back at the peak
of 45 kts. This upgrade followed a relocation to the north based on
multi-spectral satellite imagery and a 04/2115 UTC QuikScat pass.
(Through this weakening and re-intensification episode JMA's 10-min
avg MSW remained constant at 40 kts, which was that agency's peak
intensity for Bebinca. PAGASA's peak 10-min avg MSW estimate for
Tropical Storm Neneng was 45 kts.)
At 05/0600 UTC Tropical Storm Bebinca was located approximately
550 nm south of Kyoto, Japan, tracking north-northeastward at 14 kts.
The tropical storm's heading became increasingly northeastward on
5 October. By 1800 UTC the LLCC had decoupled from the deep convection
and JTWC lowered the MSW to 35 kts. Both JTWC and JMA downgraded Bebinca
to a 25-kt tropical depression at 06/0000 UTC and issued their final
warnings with the system centered about 300 nm northwest of Iwo Jima.
At the same time a developing extratropical LOW was located at 32.0N/
139.0E, or less than 200 nm north of the weakening Bebinca. The remnants
of Bebinca were apparently entrained into the extratropical system, which
subsequently absorbed the remnants of Tropical Storm Rumbia as it sped
eastward.
C. Damage and Casualties
------------------------
No damage or casualties have been directly attributed to Tropical
Storm Bebinca/Neneng, but according to the online Wikipedia report,
the extratropical LOW which absorbed the former tropical cyclone swept
across coastal waters of Honshu, leaving 33 persons either dead or
missing.
(Report written by Gary Padgett)
TROPICAL STORM RUMBIA
(TC-20W / TS 0617)
2 - 6 October
-----------------------------------------
Rumbia: contributed by Malaysia, is the name of a type of palm tree
which yields sago. The tree commonly grows along riverbanks,
in swampy areas, or in areas near water.
A. Introduction and Storm Origins
---------------------------------
Tropical Storm Rumbia, like its partner Bebinca, was a large, loosely-
organized tropical cyclone with monsoon depression characteristics.
Both systems featured a large outer circulation with massive deep
convection located relatively distant from the center. In the final
days of September disturbed weather covered a large area extending from
north of Pohnpei northward and well east of the Marianas. A STWO issued
by JTWC at 29/1500 UTC mentioned an area of convection which had
persisted just north of Pohnpei. A 29/0751 UTC QuikScat pass had
revealed an elongated LLCC with associated deep convection. During
subsequent days the main center of action seemed to migrate generally
northward with favorable divergence aloft but with moderate vertical
shear. At 1800 UTC on 2 October JMA upgraded the system to a 30-kt
tropical depression located approximately 450 nm east-southeast of the
northernmost Mariana Islands. A STWO issued by JTWC around the same
time noted that a 02/0737 UTC QuikScat pass had indicated a developing
LLCC on the eastern periphery of the monsoon trough with 20-kt westerly
winds southwest of the center and sea level pressures near 997 mb. JTWC
at that time upped the potential for development to 'fair'.
B. Synoptic History
-------------------
JMA upgraded the depression to Tropical Storm Rumbia at 1200 UTC on
3 October with the center about 500 nm east of the northern Marianas.
A few hours later JTWC issued a TCFA for the system, noting that the
system lay under a 200-mb LOW with significant dry air over the western
semicircle and weak to moderate vertical shear. Rumbia continued slowly
northward and JMA upped the winds to the peak of 45 kts (10-min avg) at
04/0000 UTC with the large cyclone centered approximately 475 nm east-
northeast of the northernmost Marianas. The intensity was based upon
an earlier QuikScat pass which had indicated legitimate 40-45 kt winds
in the northeastern quadrant. According to Mark Lander, QuikScat winds
are closer to a 10-min avg more so than a 1-min avg. JTWC at this point
had still not initiated warnings on Rumbia, and did not do so until
04/1800 UTC when the first warning on Tropical Depression 20W was
issued. The system was then centered approximately 600 nm east of Iwo
Jima and plodding northwestward. (JTWC had issued two TCFAs on the
developing system: one at 03/1700 UTC and the second at 04/1630 UTC.)
QuikScat data continued to report winds above gale force extending
outward for hundreds of miles. Observations from the ship Liberty Eagle
around 0000 UTC on 5 October of winds of 37 to 44 kts corroborated the
QuikScat winds. JTWC finally upgraded Rumbia to a minimal tropical storm
at 05/1200 UTC. However, they never raised the MSW above 35 kts and
maintained Rumbia as a tropical storm for only 12 hours. Rumbia began
to accelerate northward and weaken late on the 5th. JTWC downgraded the
cyclone to a tropical depression at 06/0000 UTC with the center located
560 nm east-northeast of Iwo Jima and moving northward at 18 kts. At
the same time JMA lowered their MSW estimate to 40 kts, but six hours
later downgraded Rumbia to a 25-kt dissipating depression. The LLCC
had become completely exposed and was rapidly deteriorating. The
remnants of Rumbia were ultimately absorbed into the same extratropical
LOW which had absorbed the remnants of Tropical Storm Bebinca.
As noted above JMA's peak estimated MSW for Rumbia was 45 kts (10-min
avg) with minimum CP estimated at 985 mb.
C. Damage and Casualties
------------------------
No reports of damage or casualties resulting from Tropical Storm
Rumbia have been received.
D. Additional Discussion
------------------------
Rumbia was a very unusual case in that the intensity estimates
assigned by JMA were consistently higher than those assigned by JTWC.
As noted in the narrative above, QuikScat data in addition to ship
observations revealed the existence of winds in the 40-45 kt range,
so in the author's opinion, the JMA estimates should be considered
as the more representative of the system's intensity.
Rumbia was one of those not-too-infrequent Western Pacific systems
of monsoon origin which just do not "behave" according to the Rules of
Proper Behavior for Young Tropical Cyclones according to the Dvorak
method. Mark Lander has pointed this out time after time over the years.
Based on the observed intensity Rumbia should have been earning Dvorak
ratings of around T3.0. However, the CI numbers from AFWA and JTWC
remained at T2.0, except around 1800 UTC on 5 October, when they reached
T2.5 just before the system began to shear apart. Also, in the earlier
stages the numbers from SAB were at T2.0, but early on the 4th the
SAB analyst assigned a ST2.5 rating using the Hebert-Poteat method for
subtropical cyclones. Rumbia was not a subtropical system, but exhibited
some characteristics of subtropical cyclones such as a lack of deep
convection near the center and a large band well to the east of the LLCC.
However, it is still somewhat surprising that JTWC based their
intensity estimates only on satellite analysis and ignored the valid
QuikScat data and ship reports. Another interesting thing--the NWS
forecast office on Guam issues warnings for many of the islands in the
Marianas and Micronesian groups. Normally, the Guam Weather Forecast
Office (WFO) utilizes the MSW value reported in JTWC's warnings. However,
in the case of Rumbia, they deviated from this practice. The first
two Guam WFO advices, issued at 04/2100 and 05/0300 UTC, respectively,
estimated the MSW at 45 kts. This was prior to JTWC upgrading Rumbia
to minimal tropical storm status. According to one of the Guam WFO
forecasters, they normally do follow JTWC but in this case felt the
observations warranted doing otherwise. In his words, one "needs to
remember: the Dvorak technique makes a good servant but a bad master."
Here's another interesting observation from Mark Lander posted on
4 October, during the period in which Tropical Storms Bebinca and Rumbia
were operating to the west and east of Guam, respectively:
"Southwesterly monsoon winds have been blowing for several days on Guam.
We have had upwards of 8 inches of rain in a 4-day period. Very thick
smog has overspread our region as a result of the monsoon trajectory
bringing us thick smog from Indonesia (caused by seasonal slash-and-burn
activities there). The thick aerosol load has an interesting side effect
of enhancing the lightning efficiency of the showers and squalls in the
monsoon flow."
(Report written by Gary Padgett)
TYPHOON SOULIK
(TC-21W / TY 0618)
8 - 17 October
--------------------------------------
Soulik: contributed by the Federated States of Micronesia, is a
traditional Pohnpei Chief's title
A. Introduction and Storm Origins
---------------------------------
Typhoon Soulik was a mid-October typhoon of moderate intensity which
stalled near Iwo Jima as it reached typhoon intensity and later recurved
harmlessly out to sea to the southeast of Japan. On 6 October an area
of convection had developed approximately 130 nm north-northeast of
Kwajalein. There was an area of cyclonic shear at the surface attended
by some flaring convection; however, there was no evidence of a LLCC at
the time. A surface circulation gradually took shape and JMA began
referencing the system as a tropical depression at 1200 UTC on 8 October
in their High Seas Bulletins. JTWC issued a TCFA for the disturbance
at 08/1630 UTC, placing the center about 310 nm north-northeast of
Pohnpei. A TRMM pass at 08/1349 UTC had revealed banding convection
wrapping into the northern periphery of a consolidating LLCC. An upper-
level analysis showed an anticyclone aloft and a TUTT cell to the north-
west of the disturbance. These two features were combining to facilitate
dual poleward and equatorward outflow channels with low vertical shear.
The first JTWC warning on Tropical Depression 21W was issued at 0000
UTC 9 October, placing the center about 770 nm east of Guam and tracking
northwestward at 15 kts. TD-21W was upgraded to a tropical storm at
1200 UTC as it tracked along the southwestern periphery of a subtropical
ridge anchored north of Wake Island. At 09/1800 UTC JMA upgraded the
system to tropical storm status and assigned the name Soulik.
B. Synoptic History
-------------------
The newly-christened tropical storm's intensification proceeded at a
somewhat slow rate due to restricted outflow and moderate vertical wind
shear as Soulik moved steadily on a northwesterly trajectory which
gradually became west-northwesterly. By 1200 UTC on 10 October Soulik's
winds had reached 55 kts with the storm centered about 360 nm northeast
of Saipan. The MSW remained at around 55-60 kts for two full days as
the cyclone moved in the direction of Iwo Jima, tracking along the
southwestern periphery of a subtropical ridge (STR) centered north of
Wake Island. Another STR to the west of the tropical cyclone had begun
to build northward, forcing the system to track more to the north-
northwest. In addition a passing mid-latitude shortwave trough had
created a weakness in the STR to the northeast of the storm, enhancing
the more northerly track.
The primary inhibiting influence on Soulik's intensification had been
significantly-reduced poleward outflow. A poleward outflow channel had
developed by the 12th and accordingly Soulik reached typhoon intensity
at 12/1200 UTC while centered only 80 nm south of Iwo Jima, moving north-
northwestward at 7 kts. Due to a "tug-of-war" between the eastern and
western STRs, Typhoon Soulik moved little as it intensified to its peak
intensity of 90 kts. Twenty-four hours after attaining typhoon status,
the storm was quasi-stationary only about 55 nm south-southwest of the
island of Iwo Jima. As the STR to the west began to weaken and another
mid-latitude trough approached, the storm began to slowly nudge
northward. The closest approach to Iwo Jima came around 14/0600 UTC
when the center of Soulik's eye was placed only 20 nm west of the island.
Based on JTWC's warning at that hour, the island would have been within
the radius of typhoon-force winds.
By 14/1200 UTC Typhoon Soulik was located about 50 nm north-northwest
of Iwo Jima and the heading had begun to bend a little to the north-
northeast at 7 kts. Some strong westerlies associated with the
approaching trough were beginning to impinge on the typhoon's north-
western quadrant, and the intensity was lowered to 80 kts. By 15/0000
UTC Soulik was located approximately 170 nm north of Iwo Jima and moving
north-northeastward at 13 kts. The MSW was estimated at 75 kts, and
there were signs that the cyclone was beginning extratropical transition
with stratocumulus in the western quadrants and a notch of drier air
intruding into the southern quadrants. Soulik continued to accelerate
to the northeast and weaken as the 15th progressed. The storm was down-
graded to a 60-kt tropical storm at 1200 UTC, and JTWC declared Soulik
extratropical and issued their final warning at 1800 UTC. The system
was then located roughly 400 nm southeast of Tokyo and racing north-
eastward at 27 kts. JMA maintained Soulik as a typhoon through 1800
UTC, and then as a tropical storm for another 12 hours, finally declaring
the system extratropical at 16/1200 UTC. The storm continued moving
rapidly eastward, crossing the Dateline around 1600 UTC on 17 October.
The final reference to the system in JMA's High Seas Bulletins placed
a weakening 35-kt gale far to the south of the Aleutians at 17/1800 UTC.
The maximum 10-min avg MSW assigned to Typhoon Soulik by JMA was
75 kts with an attendant minimum CP of 955 mb.
C. Meteorological Observations
------------------------------
As noted above, Typhoon Soulik was essentially stalled very near Iwo
Jima at the time of its peak intensity, and based upon JTWC's wind radii,
the island should have experienced sustained typhoon-force winds.
However, no synoptic observations have been received by the author. The
online Wikipedia report states that 205 mm of rainfall was recorded on
Pagan Island in the Marianas in association with Soulik.
D. Damage and Casualties
------------------------
No reports of damage of casualties resulting from Typhoon Soulik have
been received.
(Report written by Gary Padgett)
SUPER TYPHOON CIMARON
(TC-22W / TY 0619 / PAENG)
26 October - 6 November
----------------------------------------------
Cimaron: contributed by the Philippines, is the name of a Philippine
wild ox
A. Introduction and Storm Origins
---------------------------------
Cimaron was the third of six typhoons to strike the Philippine
Archipelago during 2006, and although the most intense, it was not the
deadliest. The cyclone was also the fifth of six typhoons during 2006
to reach JTWC's super typhoon threshold of 130 kts--not counting Ioke
which was a visitor from the Central North Pacific and entered the
Northwest Pacific basin already at super typhoon intensity on 27 August.
(There is a distinct possibility that Typhoon Chebi in November also
reached super typhoon status, but it was not officially upgraded
operationally.)
An area of convection developed on 24 October near 13.0N/150.0E, or
approximately 320 nm east of Guam. Convection was flaring over an area
of low-level cyclonic shear, and upper-level conditions were favorable
with good divergence and low vertical shear. By the next day the
primary area of disturbed weather was relocated to the south-southwest
of Guam. A LLCC appeared to be consolidating, and the environment was
still favorable for cyclogenesis. At 0600 UTC on the 26th JMA began
to classify the system as a weak tropical depression, and six hours later
upped the winds to 30 kts. The system was by now roughly a couple
hundred miles to the north of Yap with improving poleward outflow. JTWC
issued a TCFA around 1300 UTC, and the first warning on Tropical
Depression 22W was issued at 26/1800 UTC. The center of TD-22W was then
located about 750 nm east of Manila, tracking west-northwestward at
11 kts. JTWC upgraded the depression to a tropical storm at 27/0000 UTC,
and at the same time PAGASA initiated bulletins on Tropical Depression
Paeng. Six hours later both JMA and PAGASA upgraded the system to
tropical storm status with JMA assigning the international name Cimaron,
which incidentally happens to be a name contributed by the Philippines.
B. Synoptic History
-------------------
With a strong subtropical ridge to the north, Tropical Storm Cimaron
embarked on a general west to west-northwesterly track which would lead
to a rendezvous with the island of Luzon in 2 1/2 days. By 27/1200 UTC
Cimaron was located about 550 nm east of Manila and had intensified to
50 kts. With dual outflow channels developing, Cimaron began to deepen
rapidly. By 28/1200 UTC the MSW had increased to 100 kts; eighteen hours
later Cimaron's winds had climbed to 155 kts--the most intense typhoon
of 2006. The estimated CP (per JMA's analysis) dropped 65 mb in 24 hours
from 975 mb at 28/0600 UTC to 910 mb at 29/0600 UTC. (See discussion
on Cimaron's intensity in Section D below.) The storm was a fairly
compact typhoon with the gale radius being about 135 nm. Super Typhoon
Cimaron/Paeng was located about 175 nm northeast of Manila at 29/0600 UTC
and closing in on the eastern coast of Luzon. A TRMM overpass at
29/0540 UTC revealed the presence of two tiny concentric eyewalls
separated by only a few kilometres.
The eye of the small but extremely intense typhoon made landfall just
north of Casiguran around 1300 UTC on 29 October, still at its peak
intensity of 155 kts. Typhoon Paeng transited Luzon fairly quickly--by
0000 UTC on the 30th the center had emerged off northeastern Luzon into
the South China Sea. A subtropical ridge to the north kept the typhoon
on a general westerly track for a day or so, but a weakness developed
in the ridge and Cimaron/Paeng began to turn to the northwest with a
great reduction in its forward motion. By 0600 UTC on 1 November Typhoon
Cimaron had become essentially stationary about 230 nm south-southeast
of Hong Kong. After emerging from Luzon the MSW had become steady-state
around 90 kts, but late on 31 October began to increase again, reaching
a secondary peak intensity of 110 kts at 01/0600 UTC. The rejuvenation,
however, was short-lived. As Cimaron sat basking in the sun over the
South China Sea, it began to weaken under the combined unfavorable
influences of increasing vertical shear, entrainment of dry air from the
west, and suppressed equatorward outflow.
The storm weakened quite rapidly from its 110-kt secondary peak at
0600 UTC on 1 November. At 1800 UTC on the 2nd both JMA and JTWC down-
graded Cimaron to a 55-kt tropical storm, located about 280 nm south-
southeast of Hong Kong. The weakening cyclone was moving southwestward
at 5 kts due to a north-northeasterly flow at the 850-700 mb level as
strong ridging persisted over southern China. JTWC downgraded Cimaron
to a tropical depression at 1800 UTC on 3 November and issued their
final warning at 04/1200 UTC with the system centered approximately
390 nm south-southeast of Hong Kong, moving southwestward at 4 kts.
Interestingly, JMA was still maintaining Cimaron as a minimal tropical
storm at the time and continued to do so through 05/1800 UTC, downgrading
it at 06/0000 UTC. The system quickly weakened into a low-pressure area
with the final reference in JMA's High Seas Bulletins placing it near
11.0N/115.0E at 06/1800 UTC. (Note: The track map accompanying the
online Wikipedia report on Cimaron depicts the residual LOW accelerating
toward the southwest and moving into southern Vietnam and skimming along
the southeastern Vietnamese coastline. I did not save the JMA bulletins
beyond 06/1800 UTC as the system was no longer being referred to as a
tropical depression.)
C. Damage and Casualties
------------------------
According to the online Wikipedia report, at least 19 people were
killed in the northern Philippines, mostly by drowning. An additional
15 persons were reported missing. Damage from Typhoon Paeng was
estimated at around $9 million U. S. dollars. In a coastal town near
where the center made landfall, 90% of the houses were damaged.
D. Additional Discussion
------------------------
The highest 10-min avg MSW estimated by both JMA and PAGASA for Super
Typhoon Cimaron/Paeng was 105 kts. The highest 1-min avg MSW reported
in JTWC's warnings was 140 kts at 0600 and 1200 UTC on 29 October. In
the discussion above and also in the companion cyclone tracks file which
I prepare, I have chosen to report 155 kts as the peak 1-min avg MSW
for Cimaron. Ever since I began writing the tropical cyclone summaries
in 1997 I have rarely departed from using JTWC's warnings as the source
of a 1-min avg MSW to report. However, in the case of Cimaron, I felt
that there was sufficient evidence that the cyclone was more intense than
140 kts to warrant deviating from my long-standing practice.
JTWC's intensity during the time under consideration was based solely
on the Dvorak ratings by that agency's satellite analyst(s), which were
T7.0/7.0. However, AFWA rendered a rating of T7.5/7.5 at 0531, 1131,
and 1431 UTC on the 29th, noting that constraints were broken due to
the rapid intensification. Also, the SAB analysis at 29/0833 UTC was
T7.5/7.5. The SAB rating at 29/0233 UTC had been T7.0/7.0, but the
remarks indicate that the analyst felt very strongly that the system was
more intense, but held back out of respect for the Dvorak rules. He
also noted that the visual Data-T number was T8.0. In an e-mail, the
same SAB analyst stated that he could not remember a storm with a 26 C
eye being maintained for nearly 10 hours (and in GOES imagery at that!)
while remaining embedded in a CMG (and at times CDG) ring without some
breakdown. Also, the JTWC satellite bulletins at 29/0230 and 29/0830
UTC noted that the AODT numbers were 7.6 and 7.8, respectively.
As a result of this, I requested Dr. Karl Hoarau (whom I regard as
an expert Dvorak analyst), to study imagery of Cimaron and render his
opinion. Karl agreed with the SAB and AFWA analyses and estimated a
peak intensity of 155 kts.
This discussion should not be taken as a criticism of JTWC. Indeed,
the difference was only 1/2 T-number, and I have heard forecasters
say "I'll never argue half a T-number with you." And forecasters as a
general rule tend to be more conservative as they are the ones who
actually assign the reported intensity estimates. It is really an
academic issue--one would prepare for a 155-kt cyclone exactly as one
would prepare for a 140-kt cyclone.
However, just because it is an academic issue is not to say that it
isn't important. I personally feel that in post-storm analyses and "best
track" intensity determinations, every effort should be made to fine tune
the MSW to the very best 5-kt value. The official "best track" databases
are often the bases for climatological studies of tropical cyclones, and
since the vast majority of the MSW values in the databases, globally
speaking, are based on Dvorak analysis techniques (with perhaps nowadays
microwave and scatterometer data playing an increasing role), it is very
important that the analyses lying behind the estimated intensities be
performed in as consistent manner as possible. Otherwise, spurious
trends could be inferred from the data, or conversely, real trends in
some parameter could be masked due to inconsistencies in the manner in
which the intensities were determined.
(Report written by Gary Padgett)
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for October: 1 cyclonic storm **
** - no warnings issued on this system by JTWC
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.
CYCLONIC STORM OGNI
(BOB0602)
28 - 30 October
---------------------------------------
Ogni: contributed by Bangladesh
Cyclonic Storm Ogni formed in late October just off the southeastern
coast of India and moved northward and inland, hugging the coastline all
the way. An area of convection developed on 27 October about 100 nm
west of Colombo, Sri Lanka. Satellite imagery revealed a LLCC developing
in the Palk Strait with persistent convection. An upper-level analysis
indicated low to moderate vertical shear with good equatorward outflow
and developing poleward outflow. Satellite bulletins from JTWC and AFWA
indicated that a tropical depression with winds of at least 25 kts likely
had developed by 28/1130 UTC and was centered very near the coast of
India about 75 nm south-southwest of Madras. Environmental conditions
in general were favorable for development--the only negative factor was
the system's proximity to land. At 28/2300 UTC JTWC upgraded the
potential for development to 'fair', and at 0300 UTC on 29 October the
IMD issued a bulletin classifying the developing system as a depression.
The depression continued to move on an almost due northerly track just
off the Indian coastline. Satellite classifications from SAB indicate
that winds had likely reached 30 kts by 29/0230 UTC and 35 kts six hours
later. IMD upgraded the system to deep depression status at 0900 UTC,
and at 1200 UTC further upgraded it to Cyclonic Storm Ogni, located
about 27 nm east of Kaveli. A STWO issued by JTWC at 29/1100 UTC noted
that the center was offshore with a band of deep convection wrapping
into the northern quadrant from the east. Maximum winds were estimated
at 25-35 kts, but JTWC elected to not issue warnings on the system,
although a TCFA was issued at 1130 UTC.
Satellite classifications from SAB suggest that Ogni likely reached
a peak intensity of 45 kts (1-min avg) around 29/1430 UTC, but had begun
to slowly weaken by 0230 UTC on the 30th. According to an IMD bulletin
at 30/0300 UTC Ogni was centered very close to Ongole. The storm
continued to move northward and had moved inland south of Vijayavada
by 0830 UTC, quickly weakening thereafter. With the center nearing the
coast, JTWC had cancelled the TCFA at 30/0230 UTC. A radar image from
an IMD website made at 30/0443 UTC depicts Ogni with the center almost
on the Indian coastline and appears indicative of a system of tropical
storm intensity.
No damage or casualties are known to have resulted from Cyclonic
Storm Ogni.
(Report written by Gary Padgett)
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for October: 1 tropical disturbance
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 Tropical Cyclone Advisory Centres in Mauritius and
Madagascar with longitude 55E being the demarcation line between their
respective areas of naming 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.
Southwest Indian Ocean Tropical Activity for October
----------------------------------------------------
The first tropical disturbance of the 2006-2007 season in the South-
west Indian basin formed in mid-October. Around 0000 UTC on 18 October
a tight LLCC with flaring convection was located approximately 600 nm
west-northwest of Diego Garcia. JTWC issued the first of three TCFAs
at 18/0900 UTC, noting that deep convection was increasing over a
developing LLCC in the presence of vigorous poleward outflow and within
a region of low to moderate vertical shear. Winds were estimated to
be 25-30 kts. Over the next day the system drifted westward with
little change. MFR issued the first warning on Tropical Disturbance 01
at 19/0600 UTC, locating the center somewhat to the north at a position
approximately 250 nm east-northeast of the Seychelles. JTWC issued a
second TCFA at 0900 UTC, noting that the system was moving northwestward
at 6 kts. Interestingly, only four hours later JTWC issued a third
TCFA for the disturbance. As the system was very poorly-organized and
located in a marginal environment for strengthening, MFR issued only
very sporadic bulletins through the 21st, and JTWC cancelled their TCFA
at 1300 UTC on 20 October, downgrading the potential for development to
'poor'.
The system seemed to reform somewhat further to the south on the 21st.
A bulletin issued by MFR at 21/0600 UTC placed the center approximately
185 nm east-southeast of the Seychelles. The southward movement
continued with the system reaching a point about 125 nm northwest of
Agalega at 22/1200 UTC. At this point, MFR begin issuing regular
6-hourly warnings on Tropical Disturbance 01, estimating the 10-min avg
MSW at 25 kts. No warnings were issued on the system by JTWC, but
satellite bulletins from that agency and AFWA implied maximum 1-min avg
winds of around 30 kts from the 18th through the 22nd. The system
began drifting westward on 22 October but began to slowly weaken. The
final MFR bulletin, issued at 23/1200 UTC, placed a weak 20-kt center
approximately 185 nm north-northeast of the northern tip of Madagascar.
A track for this system was included in the companion global cyclone
tracks file prepared by the author.
Short reports with satellite pictures and small-scale maps for all
the Southern Hemisphere systems may be found at the following link:
http://en.wikipedia.org/wiki/2006-07_Southern_Hemisphere_tropical_cyclone_season>
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for October: No tropical cyclones
*************************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for October: No tropical cyclones
*************************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for October: 1 tropical depression
1 tropical cyclone of hurricane intensity
Sources of Information
----------------------
The primary sources of tracking and intensity information for
South Pacific tropical cyclones are the warnings and advisories
issued by the Tropical Cyclone Warning Centres at Nadi, Fiji (for
waters north of latitude 25S), and Wellington, New Zealand (for
waters south of latitude 25S). 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 the Southern Hemisphere
centres' 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.
South Pacific Tropical Activity for October
-------------------------------------------
For the first time since 1997, a named tropical cyclone formed in
South Pacific waters east of 160E during the month of October. The
cyclone, Xavier, not only was the first South Pacific October cyclone
in nine years, but it also became an intense cyclone, peaking at 95 kts
(10-min avg) per Fiji's analysis, or at 115 kts (1-min avg) per JTWC's
analysis. After reaching hurricane intensity, Tropical Cyclone Xavier
passed over the island of Tikopia in the Santa Cruz group, which had
been utterly devastated in late 2002 by the extremely intense Tropical
Cyclone Zoe. At one point Xavier's forecast track was southwestward
toward the islands of the Republic of Vanuatu, but fortunately the
storm shifted to a southeasterly track, relieving the threat to Vanuatu.
A report on Tropical Cyclone Xavier, written by Simon Clarke, follows.
During the time that Xavier was active, Nadi identified another system
to the east as Tropical Depression 02F. This system at 24/1800 UTC was
located east of the Dateline approximately 300 nm northwest of American
Samoa (12.0S/175.0W). TD-02F moved westward, and at one point on the
25th appeared to be increasing in organization, but as it moved across
the Dateline it began to be unfavorably influenced by the outflow from
Xavier. TD-02F crossed the Dateline at a point approximately 325 nm
north-northeast of Fiji (13.0S/180.0E), subsequently moving northwest-
ward. At 27/1800 UTC the weakening system was located about 350 nm west
of Funafuti (8.5S/176.5E) and continued to drift westward until it was
dropped from Fiji's tropical weather summaries on the 29th. Nadi
estimated that winds of 20-30 kts might be occurring up to 180 nm from
the center, but no gale warnings were ever issued for TD-02F. Since
no satellite classifications warranting tropical depression status were
issued on this system, no track was included in the companion global
cyclone tracks file.
Short reports with satellite pictures and small-scale maps for all
the Southern Hemisphere systems may be found at the following link:
http://en.wikipedia.org/wiki/2006-07_Southern_Hemisphere_tropical_cyclone_season>
TROPICAL CYCLONE XAVIER
(TD-01F / TC-01P)
20 � 28 October
-------------------------------------------
A. Storm Origins
----------------
The South Pacific Cyclone Season was off to a very early start in the
form of TC Xavier which developed prior to the official commencement
of the cyclone season on 1 November. The cyclone originated from a
persistent area of thunderstorm activity that was active in the
intertropical convergence zone stretching from the Solomon Islands
across to the north of Vanuatu for almost a week.
By 20/2100 UTC, an area of consolidating convection near a LLCC was
identified near 9.9S/167.8E. The LOW had a solid trade flow to the
south and was located in a region of superior upper outflow,
particularly to its north and east. SSTs were around 29-30 deg C.
Development of the depression was rapid and by 22/0000 UTC, RSMC Nadi
upgraded the LOW to cyclone status and officially named the system
Xavier. At this time the cyclone was located near 11.0S/167.8E, over
Santa Cruz, the eastern most group of islands in the Solomon chain.
B. Synoptic History
-------------------
Initially Xavier meandered slowly to the east of the Utupua Island
before commencing what was to become a persistent track initially to
the SSE at 6 kts and finally to the SE at 10 kts. Conditions
remained favorable for development, allowing the midget system to
intensify explosively. Within 18 hours Xavier reached hurricane
intensity with a clear eye feature developing in a tightly-wrapped
central core. The cyclone passed over Tikopia (pop. 1200), the
southernmost island in the Santa Cruz Group, famous for withstanding
Severe Tropical Cyclone Zoe in December, 2002 (see separate report).
Xavier continued to the SE at 10 kts in response to the northwesterly
steering flow. A change of path to the W or SW was forecast, but never
eventuated, which is counted as somewhat of a blessing as this track
would have taken Xavier through the main islands of Vanuatu. Peak
intensity was attained at 24/0600 UTC near 13.7S/169.6E (approx. 220 nm
NE of Vila, Vanuatu, and 350 nm WNW of Nadi, Fiji). Central
pressure was estimated to be 930 hPa with maximum 10 min-avg winds of
95kts. Peak intensity was maintained for eighteen hours; thereafter
Xavier underwent an equally impressive weakening process losing
cyclone status at 26/0000 UTC as aggressive upper wind shear and
cooler sea surface temperatures eroded the system�s convective
structure, displacing it well to the SE of the LLCC. At about
this time, Xavier�s path to the SE was blocked by a low-level south-
easterly surge from a solid mid-level ridge building to its south.
The remnant LLCC was forced back to the NNW at a rapid pace and
ultimately the LLCC lost identity a little over twenty four hours
later.
(Note: The peak 1-min avg MSW estimated by JTWC for Tropical Cyclone
Xavier was 115 kts at 24/0000 and 24/1200 UTC.)
C. Damage and Casualties
------------------------
There were no casualties as a result of Xavier. Minor tree damage
was reported from the islands of Utupua and Vanikolo. Extensive
damage to food crops and flooding occurred at Tikopia. However,
Radio New Zealand reported that overall damage at Tikopia was
considered to be light given the circumstances. The cyclone side
swiped the eastern islands of Vanuatu, producing rough seas, beach
erosion and squally winds. However, no significant damage was
reported.
(Report written by Simon Clarke)
*************************************************************************
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 2004 as an
example), the archived products can be found at:
http://www.nhc.noaa.gov/archive/2004/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: http://199.10.200.33/jtwc.html>
Also, TPC/NHC has available on its webpage nice "technicolor"
tracking charts for the 2006 Atlantic and Eastern North Pacific
tropical cyclones; also, storm reports for all the 2006 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: summ0610.htm
Updated: 6th February 2007 |
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