Unprecedented Hurricane Tomas pounding the Lesser Antilles

By: Dr. Jeff Masters , 3:38 PM GMT on October 30, 2010

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Hurricane Tomas, an unprecedented Lesser Antilles hurricane for so late in the season, is bearing down on the islands of St. Lucia and St. Vincent with Category 1 winds of 75 mph. Recent radar imagery from the Martinique radar shows that Tomas is still in the organizing stage, with an eyewall that just closed off, and a weak area of echoes on the south side, due to modest wind shear of 10 knots caused by southerly upper-level winds. The Hurricane Hunters reported top surface winds in the northern eyewall near 75 mph. St.Lucia figures to get the worst blow from Tomas, as this island will experience the strong right-front quadrant of the storm--the north eyewall. Winds on the island were sustained at 46 mph, gusting to 67 mph, at 11am EDT. Winds at Barbados peaked at 37 mph, gusting to 56 mph, early this morning, and the pressure bottomed out at 994 mb. Satellite loops of Tomas show a large and well-organized Cape Verdes-type hurricane, with good upper level outflow on all sides except the south, and an impressive amount of heavy thunderstorm activity. This is a very dangerous hurricane that is just beginning to get going. You can follow the progress of Tomas through the islands today with our wundermap zoomed in on St. Lucia.


Figure 1. Morning radar image from the Martinique radar shows the eye of Tomas moving between the islands of St, Lucia to the north and St. Vincent and the Grenadines to the south. The southern portion of the eyewall had just closed off with this image. Image credit: Meteo France.

Intensity forecast for Tomas
Now that the eyewall of Tomas has completely closed off, a period of steady and possibly rapid intensification lasting until Sunday afternoon is likely. The intensification rate may then be slowed by an increasing flow of southwesterly upper-level winds, which are expected to bring dry air and a moderate 15 - 20 knots of wind shear to Tomas Sunday through Tuesday, according to the latest SHIPS model forecast. Shear is then expected to relent, allowing more intensification on Wednesday. Water temperatures are a record warm 29.5°C and the Tropical Cyclone Heat Potential--a measure of the total heat content of the ocean--is a very high 100 kJ/cm^2, which is very favorable for rapid intensification. I expect the Tomas will strengthen to a Category 3 or 4 hurricane by Wednesday.


Figure 2. Hurricane specialists Robbie Berg (background) and Dan Brown (foreground) discuss the latest data on Tomas last night at the National Hurricane Center.

Track forecast for Tomas
The computer models have come into better agreement this morning that after Tomas reaches the central Caribbean 4 - 5 days from now, a turn to the north or northeast is likely, in response to a strong trough of low pressure expected to develop over the Eastern U.S. The exact timing of this turn to the north or northeast is difficult to predict at this time, as steering currents will be weak in the Caribbean after Tomas passes through the Lesser Antilles today and Sunday. At this time, is appears that the Dominican Republic and Haiti are most at risk from a strike by Tomas, though the storm could move as far west as Jamaica, or as far east as the northern Lesser Antilles Islands.


Figure 3. Hurricane specialist Dan Brown computes Tomas' radius of tropical storm force winds using the old-fashioned paper track plot and dividers technique. Hurricane specialists at NHC commonly use a paper track plot to mark all storm center fixes and compute the current motion of the storm. A storm's current heading and speed in NHC advisories is usually a 12-hour average of the motion up until the final fix position.

Tomas, Shary, and the 2010 hurricane season in perspective
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 intensification of Shary and Tomas into hurricanes today brings the total number of hurricanes this season to twelve, tying 2010 with 1969 and 1887 for second place for most hurricanes in a season. The record is held by 2005 with fifteen hurricanes, and I don't think we'll beat that record this year!

The formation of Tomas 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 (61.5°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 61.5°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 61.5°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 a storm I flew into with the Hurricane Hunters--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. According to Chenoweth (2008), Tomas is the first tropical storm to cross through the Lesser Antilles Islands south of 16°N this late in the year since 1724. In that year, a tropical storm on 12 November crossed the islands at 13.7°N 61.5°W, and later became a hurricane that affected Jamaica. There was also a hurricane on 30 October 1671 that crossed 61.5°W at 13.3°N, and did damage on Barbados.

Another unusual aspect of Tomas' formation is that we now have two simultaneous hurricanes in the Atlantic Ocean on October 30. There has been only one hurricane season since 1851 that had had two simultaneous hurricanes later in the year--1932, when Hurricane Ten and Hurricane Eleven both existed November 7 - 10. Today is also the 5th latest date in the season that there have been two simultaneous named storms in the Atlantic. 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.

References
Chenoweth, M. and D. Divine (2008), "A document-based 318-year record of tropical cyclones in the Lesser Antilles, 1690-2007", Geochemistry, Geophysics, Geosystems, 9, doi:10.1029/2008GC002066.

Next update
I'll have more on Sunday by 3pm EDT. I'm headed home to Michigan today, after a very valuable week here at the National Hurricane Center. The experience gave me a new appreciatation for just how good the forecasters are at what they do. NHC's hurricane experts are truly world-class, and we are very fortunate to have such a talented group of hard-working forecasters keeping us informed on the dangers we face from Atlantic hurricanes.

Jeff Masters

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443. SLU
439. CaribBoy 4:13 PM AST on October 30, 2010

Things are really starting to happen now. St. Lucia is very mountainous so one can imagine those persons living on hillsides exposed to the easterly winds might have had gusts to over 120mph.
Member Since: July 13, 2006 Posts: 12 Comments: 4878
F-L-O-O-D-M-A-N.

It is a little dead in here considering a Cat 1 is out there threatening land.

I guess they are either banned or unable to post because there is no electricity/internet connection.
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Quoting Relix:

Unlikely. NHC never does drastic stuff like that, especially when the system is moving like they forecast, albeit slower.

But if the system change it's curse, they must change the projected path drasticly!!!jmo
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Quoting SLU:
Here's an update on the weather station at Hewanorra International Airport which just came through the radio:

At 3:17pm a wind gust of 100mph was recorded in St. Lucia.

Between 3pm and 4pm the winds were sustained around 63mph over a 10-minute average.


Wow...
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Quoting SLU:
Here's an update on the weather station at Hewanorra International Airport which just came through the radio:

At 3:17pm a wind gust of 100mph was recorded in St. Lucia.

Between 3pm and 4pm the winds were sustained around 63mph over a 10-minute average.


wow
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Quoting Hurricanes101:


yup its the latest run, I posted the full run out to 10 days and while it is true the ECMWF turns in NE, it also turns it back west after that and the system meanders for a few days


Thomas' track wont be easy to predict
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radar shows Tomas moving WNW between St Lucia and St Vincent
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Quoting weatherwatcher12:
Oh sorry, I thought I saw a 18z somewhere.


there is no 18Z run of the ECMWF
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Oh sorry, I thought I saw a 18z somewhere.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Quoting CaribBoy:


Look at the date above the loop : 12Z30OCT2010.
This is the latest run.


yup its the latest run, I posted the full run out to 10 days and while it is true the ECMWF turns in NE, it also turns it back west after that and the system meanders for a few days
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433. SLU
Here's an update on the weather station at Hewanorra International Airport which just came through the radio:

At 3:17pm a wind gust of 100mph was recorded in St. Lucia.

Between 3pm and 4pm the winds were sustained around 63mph over a 10-minute average.
Member Since: July 13, 2006 Posts: 12 Comments: 4878
Quoting weatherwatcher12:

That's an old run.


Look at the date above the loop : 12Z30OCT2010.
This is the latest run.
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431. JRRP
Quoting weatherwatcher12:

That's an old run.

no
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Mixed, good to hear from you. What part of Soufrire? I know that like you said it is surrounded on the esat, north adn south by mountains, so that should help. The South is definitely getting hit hard, but is it not the least densely populated? obviously the airport is there, but otherwise?
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Quoting weatherwatcher12:

That's an old run.


no its not, but its also not the whole run, the ECMWF actually has the system meander near Jamaica for about 4 days

After it turns it NE and turns it back west again. You can see the sharp turn NE on days 5 and 6, but then it turns back west

12Z ECMWF

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Rains are still pouring here in Barbados...thunder & lighting has just begun..
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Quoting CaribBoy:
The ECMWF also shows the hard NE turn Link

That's an old run.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
The ECMWF also shows the hard NE turn Link
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Quoting Dakster:


Do you think PR will be "in the cone" next update?


Dak! What's up?

Call me, if you get a chance?
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Yeah, I can see that the NC hasn't really been following the models... I guess the "humans" see things that the "computers" cannot.

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Little slow on here for a Category 1 hurricane entering the Caribbean
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422. Mixed
St Lucia Getting Some Serious Rain And Wind Now But Places Like Soufriere Seem To Be Okay Since It Is Mostly Surrounded By Mountains, For The South Its A Mess, Im in the north and its not looking to good coming into the night
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Quoting Dakster:


Do you think PR will be "in the cone" next update?

I doubt that, the NHC has hinted that they aren't going with the models.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Since there are so many of my favorite posters on today and the season will soon be over, I'd like to take the time to say "THANK YOU" for all you do. The imfo, videos and especially the graphics are so much appreciated....and so often many of you are taken for granted. Just keep up the great work.
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419. SLU
Quoting GBguy88:


In your experience, how do you think the island will fare?


Not very well at all based on the reports because of the rapid development, limited warning time, unexpected slow motion, lack of preparedness and the fact that we're in the middle of our biggest cultural festival this weekend so most person were in a festive mood.

St. Lucia did well during hurricane DEAN (100mph) in 2007 but that was because we were very well prepared but today we were not ready for TOMAS at all.
Member Since: July 13, 2006 Posts: 12 Comments: 4878
418. Relix
Quoting Dakster:


Do you think PR will be "in the cone" next update?

Unlikely. NHC never does drastic stuff like that, especially when the system is moving like they forecast, albeit slower.
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Quoting SLU:


lol. yeah. But the island is really being pounded now.



Yeh i'm from St. Lucia but current not in the country which feels like i'm being tortured today ...


In your experience, how do you think the island will fare?
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416. SLU
Quoting largeeyes:
The Pitons are what you see in his avatar.


yep
Member Since: July 13, 2006 Posts: 12 Comments: 4878
21L/H/T/C1
MARK
13.21n/60.53w


WEAKENING FLAG OFF
FORWARD SPEED REDUCING
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414. SLU
Quoting largeeyes:


It's still moving, but seems to be moving NW. Looks like landfall has already occured on St. Vincent and is imminent in St. Lucia, probably near Choiseul and the Gros Piton(too bad there's no weather station up there.....)


lol. yeah. But the island is really being pounded now.

Quoting GBguy88:


Dumb question, but are you in St. Lucia?


Yeh i'm from St. Lucia but currently not in the country which feels like i'm being tortured today ...
Member Since: July 13, 2006 Posts: 12 Comments: 4878
Quoting jurakantaino:
Scary models for Puerto Rico the seems to be turning towards us !!!


Do you think PR will be "in the cone" next update?
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The Pitons are what you see in his avatar.
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411. HadesGodWyvern (Mod)


Tropical Low 01U (02S)
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Quoting GBguy88:


Dumb question, but are you in St. Lucia?


He's in Trinidad for studies, but obviously from St. Lucia.
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Quoting SLU:
The northern eyewall now moving over the southern part of St. Lucia. Tomas seems to have stalled completely .. the eye is not making any progress.

This is pure madness.


Dumb question, but are you in St. Lucia?
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Quoting SLU:
The northern eyewall now moving over the southern part of St. Lucia. Tomas seems to have stalled completely .. the eye is not making any progress.

This is pure madness.


It's still moving, but seems to be moving NW. Looks like landfall has already occured on St. Vincent and is imminent in St. Lucia, probably near Choiseul and the Gros Piton(too bad there's no weather station up there.....)
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406. HadesGodWyvern (Mod)
Tropical Cyclone Warning Center Perth
Tropical Cyclone Advice #4
TROPICAL LOW 01U
3:00 AM WST October 31 2010
======================================

At 2:00 am WST, Tropical Low 01U (1000 hPa) located at 8.0S 95.7E or about 485 km north northwest of Cocos Island and moving southwest has 10 minute sustained winds of 30 knots with gusts of 45 knots. The low is reported as moving southwest at 2 knots

Dvorak Intensity: T3.0/3.0/D0.5/24HRS

The low is forecast to develop into a tropical cyclone during Sunday. Recent movement has been slow and the system is expected to commence a southwards turn during the day and is likely to pass close to the Cocos Islands during Tuesday. Conditions are favourable 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 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: 8.4S 95.5E - 45 knots (CAT 1)
24 HRS: 9.2S 96.2E - 60 knots (CAT 2)
48 HRS: 11.2S 96.7E - 80 knots (CAT 3)
72 HRS: 13.2S 96.2E - 80 knots (CAT 3)

Additional Information
=======================
Over the last six hours deep convection has persisted to the west of the LLCC. Centre difficult to locate but likely to be near strong temperature gradient on the eastern side of the deep convection.

A shear pattern consistently gives a DT of 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 1518Z ASCAT pass indicates 25-30 knots in the northeast quadrant, outside the deep convection. It is possible that winds in the deep convection are between 30 to 40 knots. The final wind intensity estimate remains 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
Sunday.

Shear conditions are forecast to become more favourable during Sunday and the system will remain over SSTs>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.
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404. SLU
The northern eyewall now moving over the southern part of St. Lucia. Tomas seems to have stalled completely .. the eye is not making any progress.

This is pure madness.
Member Since: July 13, 2006 Posts: 12 Comments: 4878
Quoting Grothar:
Dynamic models:



GFS Ensemble models

Scary models for Puerto Rico the seems to be turning towards us !!!
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Quoting Relix:
New FIM Model: not good!
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The only good thing is that many of the resorts(and thus, what supports them) are in the North, and especially North east of the island.
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defiantly one to watch
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398. Relix
New FIM Model: http://fim.noaa.gov/FIMscp/jsloop.cgi?dsKeys=fim%3A&runTime=2010103012&plotName=wind_10m&fcstInc=360 &numFcsts=41&model=fim&ptitle=Experimental+FIM+Model+Fields&maxFcstLen=240&resizePlot=1&domain=244&w jet=1
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397. SLU
Quoting largeeyes:
We lost the Hewanorra International Airport, Saint Lucia (Airport) weather station.

Does anyone have the wave forecast for the Netherland Antilles?


I also heard about midday that the roof of the Hewanorra Intl. Airport was being blown off so it could explain why we've lost the reports from the station which is very bad. Those observations are vital since it's the closest station to the eye.
Member Since: July 13, 2006 Posts: 12 Comments: 4878
Steve Spurrier's mouth looks like a Cat 1 cane
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395. SLU
Quoting largeeyes:
Based on my limited experience in St. Lucia, it wouldn't take much to block a lot of roads. Very Narrow and VERY VERY VERY winding through the many hills. There is a lot of very exposed structures on the sides of those hills. Some towns are relatively low lying (soufrie for example), but even there, the sides of the town climb the surrounding hills and mountains. It's scary. I wish I could head down to help clean up, I loved my time there.


That's right. Just spoke to my brother and he said they are getting some very heavy squalls accompanied by hurricane force wind gusts and he lives in the north of the island. So farless what's taking place in the south ....
Member Since: July 13, 2006 Posts: 12 Comments: 4878
Barbados has had the all clear from their PM, seems premature to me but what do I know.
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We lost the Hewanorra International Airport, Saint Lucia (Airport) weather station.

Does anyone have the wave forecast for the Netherland Antilles?
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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.

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