Strengthening Tomas headed for the Lesser Antilles

By: Dr. Jeff Masters , 1:27 AM GMT on October 30, 2010

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Tropical Storm Tomas has exploded into existence in spectacular fashion, becoming the nineteenth named storm of this amazingly active 2010 Atlantic hurricane season. I'm reporting to you live from the National Hurricane Center tonight, where forecasters are working hard to stay abreast of Tomas' intensification. Three hurricane specialists are on duty tonight--Dave Roberts, who is handling Tropical Storm Shary, and Robbie Berg and Dan Brown, who are focusing on Tomas. The Hurricane Hunters have just left Tomas, as of 8pm EDT, and they found a significant increase in winds. Winds at their 1500 foot flight level were 70 mph, and surface winds as measured by the SFMR instrument were near 60 mph. This supports an increase in Tomas' winds to 60 mph in tonight's 8pm EDT public advisory. Since this is such a large increase in intensity from what was forecast--Tomas was not supposed to have 60 mph winds for another 24 hours--this necessitates issuance of a special advisory package. A full set of forecast maps, a marine advisory, wind probability forecast, and a discussion just went out to the world. While all this was occurring, several phone calls to Barbados, St. Lucia, and Martinique were made, alerting the islands to the fact that a Hurricane Warning may be required with the 11pm advisory tonight. NHC has both French speaking and Spanish speaking meteorologists on staff that can coordinate with the islands that don't have English as their main language. I listened in on a 5-minute conversation in French between the weather service in Martinique and NHC meteorologist Mike Tichacek, as they discussed when Martinique may want to issue a Hurricane Warning.


Figure 1. Warren VonWerne (right) of CARCAH presents the latest data from the Air Force Hurricane Hunters to hurricane specialist Robbie Berg.

Intensity forecast for Tomas
The forecasters at NHC are puzzling over the latest intensity forecasts for Tomas. The latest intensity forecast from the GFDL, HWRF, and SHIPS models are not that impressive, and they keep Tomas as a strong tropical storm or weak hurricane for the next five days. The wind shear forecast from SHIPS is particularly odd--the latest 18Z forecast predicts high wind shear of 20+ knots beginning Sunday morning, and the previous SHIPS forecast held wind shear below 15 knots for the next five days. The latest runs by the GFS, ECMWF, and UKMET models all show a very favorable environment for intensification over the next five days over the Caribbean, with Tomas positioning itself beneath an upper level high in a light wind shear environment. The best bet is that Tomas will intensify into a major hurricane over the Central Caribbean by early next week.


Figure 2. NHC meteorologist Mike Tichacek discusses the latest intensity forecast for Tomas with the Martinique weather service (in French.) In the background, hurricane specialist Dave Roberts works on advisories for Tropical Storm Shary.

Track forecast for Tomas
After Tomas reaches the central Caribbean 4 - 6 days from now, there are two possible track scenarios depicted by the models--a continued westerly motion towards Nicaragua, or a sharp turn to the north, with a track over Hispaniola or Puerto Rico. Steering currents will be weak, and we'll just have to wait and see how the steering currents evolve.

Tomas' formation location unprecedented this late in the season
Tomas' formation ties 2010 with 1995 and 1887 for 3rd place for most number of named storms in an Atlantic hurricane season. Only 2005 (28 named storms) and 1933 (21 named storms) were busier. Atlantic hurricane records go back to 1851, though there were likely many missed named storms prior to the beginning of satellite coverage in the mid-1960s.

The formation of a tropical storm so far south and east this late in the season is unprecedented in the historical record; no named storm has ever been present east of the Lesser Antilles (60°W) and south of 12°N latitude so late in the year. Hurricane Six of 1896 came close--it was also a tropical storm south of 12°N and east of 60°W on October 29, but nine hours earlier in the day. That storm recurved to the north and missed the Lesser Antilles. Tomas' track through the southern Lesser Antilles so late in the year is unprecedented. There have been only two other tropical storms that formed after October 15 south of 12°N and east of 60°W: Hurricane Jose, which was a tropical storm in that region on October 18, 1999, and Tropical Storm Nicolas, on October 16, 2003. Tomas most reminds me of Hurricane Joan of 1988, which was a tropical storm on October 14 near Tomas' current location, and later strengthened into a Category 4 hurricane that hit Nicaragua.

Another unusual aspect of Tomas' formation is that we now have two simultaneous named storms in the Atlantic Ocean on October 29. There have been only four hurricane seasons since 1851 that have had two simultaneous named storms later in the year. The record was set way back in 1887, when Hurricane Eighteen and Tropical Storm Nineteen were both active on December 8. There were three years that had simultaneous November named storms: 1932, 1961, and 2001.

Next update
I'll have more late Saturday morning.

Jeff Masters

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Quoting Neapolitan:

I can proudly say--now--that I steadfastly stuck with 20-12-6, so all that's left is for Tomas to make major--almost a lock--and one more TS to form by December 31.
When do you start working at the NHC?..:)
Member Since: September 27, 2007 Posts: 1 Comments: 21507
Quoting HadesGodWyvern:
Tropical Cyclone Warning Center Perth
Tropical Cyclone Advice #3
TROPICAL LOW 01U
9:00 PM WST October 30 2010
======================================

At 8:00 pm WST, Tropical Low 01U (1002 hPa) located at 7.8S 95.6E or about 505 km north northwest of Cocos Island has 10 minute sustained winds of 30 knots with gusts of 45 knots. The low is reported as moving west southwest at 4 knots.

Dvorak Intensity: T3.0/3.0/D1.0/24HRS

The low is forecast to develop into a tropical cyclone early on Sunday. Although it is currently moving towards the west southwest, it is expected to take a southwards turn, and is likely to pass close to the Cocos Islands on Tuesday. Conditions are favorable for intensification and there is a significant risk that people on the Cocos Islands will experience VERY DESTRUCTIVE wind gusts.

Gales are not expected on the islands during Saturday or Sunday, but may develop during Monday as the system moves closer and intensifies. The period of greatest risk will commence on Monday evening, with the system likely to pass close to the islands during Tuesday.

Tropical Cyclone Watches
========================
A Cyclone WATCH continues for a developing tropical low for the Cocos (Keeling) Islands.

Forecast and Intensity
======================
12 HRS: 8.1S 94.8E - 45 knots (CAT 1)
24 HRS: 8.6S 94.7E - 55 knots (CAT 2)
48 HRS: 10.2S 96.1E - 80 knots (CAT 3)
72 HRS: 12.3S 96.6E - 80 knots (CAT 3)

Additional Information
=======================
Over the last six hours the system has consolidated with deep convection now beginning to wrap around the centre. High SSTs are likely assisting the low to overcome moderate shear.

A shear pattern consistently gives a DT of around T3.0. The MET is 3.0 based on a 24 hour trend of D. Pattern matching does not indicate any adjustment to the MET and hence both DT and MET are 3.0. There are no FT constraints to assigning 3.0 hence FT and CI are set at 3.0. The 0244Z ASCAT pass indicates 25-30 knots in the western semicircle, however given the previously reported low bias of ASCAT it is possible that winds in this region are 30-35 knots. The final wind intensity estimate is assigned at 30 knots. This system is considered to be very close to TC intensity and gales are likely to extend around the LLCC during the next diurnally favorable period overnight.

Shear conditions are forecast to become more favorable during Sunday and the system will remain over SST>28C. The mid latitude system passing to the south erodes the mid level ridge and results in a recurvature to the southeast during Sunday. This also brings the system into light shear and by Sunday evening the system should be experiencing quite favorable conditions. The development of the system in the South China Sea should not be detrimental to this system, so based on the expected conditions, and consistent with the trend in STIPS intensity guidance it is forecast to reach hurricane force on Monday.

The spread of model guidance indicates the Cocos Islands have a high risk of impact from hurricane force winds. As the system passes south of 12S the ocean heat content becomes marginal. The system is also likely to encounter more stable boundary layer air in the wake of the mid latitude system. Hence the system is expected to weaken as it moves off to the southwest on Wednesday.

Another storm developing a little early in the southern hemisphere.
Member Since: August 9, 2009 Posts: 10 Comments: 5027
sure..and then it will dissipate like most waves do
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Shari does look a bit ragged..
Member Since: September 27, 2007 Posts: 1 Comments: 21507
Quoting CybrTeddy:


To be honest, back in July I was doubting that we'd see 16 even. This season sure proved us wrong.

I can proudly say--now--that I steadfastly stuck with 20-12-6, so all that's left is for Tomas to make major--almost a lock--and one more TS to form by December 31.
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Quoting uncljbnd:
it is a wave..just as you described.

amazing


right but will it pull northward like Thomas did
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So Tomas went north of Barbados
and is now turning west again.
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i think the forecast path will shift North again at 11 am
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Buoy well to the west..http://www.Station 42060
NDBC
Location: 16.500N 63.5W
Conditions as of:
Sat, 30 Oct 2010 12:50:00 UTC
Winds: NE (40°) at 13.6 kt gusting to 15.5 kt
Significant Wave Height: 4.3 ft
Dominant Wave Period: 4 sec
Atmospheric Pressure: 29.90 in and rising
Air Temperature: 81.9 F
Dew Point: 74.5 F
Water Temperature: 83.7 F
Member Since: September 27, 2007 Posts: 1 Comments: 21507
Quoting HurricaneDean07:
Shary is probably the most ill defined hurricane ive ever seen!


yea but recon and ASCAT proved she made it to hurricane status
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it is a wave..just as you described.

amazing
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Gotta run......Got everything you need at my WU blog with links to take you......enjoy and have a good day.
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that was kmanislander, however iwas telling everyone based on radar imagery the coc is moving due west and got flamed for it.
Member Since: August 14, 2008 Posts: 0 Comments: 1002
Shary is probably the most ill defined hurricane ive ever seen!
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what is that wave SE of Thomas... will it follow Thomas?
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Growing, and surface winds to 72 knots (83 mph), but still has some work to do...

000
URNT12 KNHC 301301
VORTEX DATA MESSAGE AL212010
A. 30/12:31:30Z
B. 13 deg 07 min N
060 deg 12 min W
C. 700 mb 3044 m
D. 65 kt
E. 056 deg 18 nm
F. 143 deg 62 kt
G. 052 deg 28 nm
H. EXTRAP 995 mb
I. 9 C / 3047 m
J. 12 C / 3047 m
K. 2 C / NA
L. RAGGED
M. C50
N. 12345 / 7
O. 0.02 / 1 nm
P. AF300 0221A TOMAS OB 10
MAX FL WIND 66 KT E QUAD 11:47:10Z
SLP EXTRAP FROM DROPSONDE
NOT A SOLID EYEWALL FIXED CTR NEAR END OF A SPIRAL IN THE EYE AREA
MAX SFC WINDS WELL WITHIN THE RADAR CENTER
SONDE RELEASED NEAR MAX SFMR WINDS RECORDED 72 KTS AT SFC
;
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Complete Update



AOI
AOI AOI AOI

AOI AOI AOI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting kmanhurricaneman:
thanks atmoaggie you just helped me prove a point
I saw your post about eye clearing...
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Quoting atmoaggie:
thanks atmoaggie you just helped me prove a point
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Quoting atmoaggie:


check out that eye....what was the wind speed on the first advisory yesterday did it jump right to tropical storm?
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Back later. BFN
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Quoting cat5hurricane:
Nice pic.
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Lightning/2000 v5.2.2 Summary (Saturday, October 30, 2010 at 7:42:11 AM N)

Since midnight (462.2 mins.):
Total strokes: 4722 (avg. 10.2/min.)
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Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting hydrus:
Good morning Ted..What about 1933. It had 21 storms..


That was the 2nd most active season. 2010 will probably either tie or beat it for 2nd place.
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The eye is starting to form up visibly.

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Quoting TampaSpin:
Just remember the trend with models late in the year. The tend to initially over play the troughs and under play high pressure. Remember what the models had Richard doing into the GOM and he went South. Not saying Tomas will be that far south but, Further WEst is a good bet.
mmmmmmm...interesting!
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Quoting CybrTeddy:
2010's the 3rd most active hurricane season

1887 had 19-11-2, 1995 had 19-11-5, 2010 has 19-12-5.

I never thought we'd see this level of activity so soon after 2005.

And we still have a month to go, plus with the likelihood of a post-season storm I am thinking 2010 will end with Walter or Alpha
Good morning Ted..What about 1933. It had 21 storms..
Member Since: September 27, 2007 Posts: 1 Comments: 21507
Just remember the trend with models late in the year. They tend to initially over play the troughs and under play high pressure. Remember what the models had Richard doing into the GOM and he went South. Not saying Tomas will be that far south but, Further WEst is a good bet.
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Quoting Neapolitan:


Indeed. Too, only two previous seasons have recorded as many as 12 hurricanes: 1969 (which also had 12) and 2005, with the all-time record of 15.


To be honest, back in July I was doubting that we'd see 16 even. This season sure proved us wrong.
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what are the thoughts on a us hit with Thomas?
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The weakness north of Tomas will be closing soon and force Tomas more due West. With the High North of Tomas....look for Tomas to speed up more than the models are showing before slowing down. That High to its north is pretty strong. Looks to me like a more Central Cuba turn to the North.
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Hurricane Tomas.
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Member Since: July 17, 2009 Posts: 71 Comments: 26562




Hurricane Thomas, with updated tracks even :)
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That Barbados radio station that was posted earlier is creeping me out with the Jesus music and Tomas.

Pretty darn ominous,

certainly a dangerous situation.
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Barbados - Lightning Rate Graph - last 24 hours

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730. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #83
SEVERE TROPICAL STORM CHABA (T1014)
21:00 PM JST October 30 2010
=================================

SUBJECT: Category Two Typhoon In Sea South Of Japan

At 12:00 PM UTC, Severe Tropical Storm Chaba (994 hPa) located at 34.7N 141.6E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The cyclone is reported as moving east northeast at 24 knots

Dvorak Intensity: T3.0

Gale Force Winds
================
350 NM from the center in northeastern quadrant
180 NM from the center in southwestern quadrant

Forecast and Intensity
=======================
24 HRS: 38.9N 149.8E - Extratropical
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Thomas now a cat 1 hurricane http://tropicalatlantic.com/models/
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Quoting Neapolitan:

Good question. Another good one: which season has had so many TCs with no hurricane strikes on the lower 48 yet causing so much devastation elsewhere?
Probably the same one.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.