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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Quoting Grenada:



I suppose we can expect that too. Hope the flooding is not too bad, that will be our problem in St. George's and Grand Anse areas.


What are the current conditions at your home right now? I believe you guys are north of St. Lucia and Barbados, which got the worst of Tomas, right?
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Quoting VAbeachhurricanes:


well mine definitely was an insult... good thing you didnt catch it :p


I can't always detect sarcasm on the internet, but in hindsight, I can clearly see the insult.

Catch it or not, I would not have been offended. It takes a lot to offend me. Much more than that.

True, I would agree. Big words are not necessarily indicative of an intelligent person. I do not use said words in order to feign intelligence. It's just become a habit of mine really, after engaging in religious debates for several years over at another website.
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1240. Grenada
Quoting DDR:

Hi grenada
You mean stinger!



I suppose we can expect that too. Hope the flooding is not too bad, that will be our problem in St. George's and Grand Anse areas.
Member Since: August 21, 2010 Posts: 0 Comments: 96
Quoting KoritheMan:


Seems to me that the anticyclone is shearing it by cutting underneath the outflow layer.


Yep, that seems to be what's happening. The NHC has been mentioning that will happen for the last few advisories now. I hope this will prevent Tomas from much further strengthening. Any cap on Tomas's strength will be much appreciated, especially because this storm could become a problem for Haiti in the coming days.
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Quoting sunlinepr:


Remember that there is an opposition in Venezuela.... Chavez is just beginning to impose Socialism / Tyrany there.... Many people still have internet, cellulars and modern tech...


If I was there, and I had the means, I'd get the heck out of dodge while I could. Not due to the socialism, but due to the tyranny.

Of course, the reality on the ground may be different than what we hear in the states. But still.
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Quoting KoritheMan:


Hey hey, I didn't mean anything by it. I apologize if that came off the wrong way. I'm just saying that the average person may not fully understand those words.

Forgive me.


well mine definitely was an insult... good thing you didnt catch it :p
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Quoting flsky:

Hmmm. Is that an insult? Just because it's late and I've only had 8 hours sleep in the last 2 nights,
doesn't mean I don't appreciate a developed brain and a good vocabulary.


Hey hey, I didn't mean anything by it. I apologize if that came off the wrong way. I'm just saying that the average person may not fully understand those words.

Forgive me.
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Quoting NCHurricane2009:


I wonder if that is some manifestation of some westerly vertical shear beginning. It seems that Tomas has been gradually struggling to keep its eye wall closed on its south and west sides for the last several hours.


Seems to me that the anticyclone is shearing it by cutting underneath the outflow layer.
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1234. DDR
Quoting Grenada:



It does appear to be carrying a sting!


Hi grenada
You mean stinger!
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1233. flsky
Quoting KoritheMan:


LOL

Actually, I considered toning it down a tad just in case my warped idea of "clarification" made flsky even more confused.

Hmmm. Is that an insult? Just because it's late and I've only had 8 hours sleep in the last 2 nights,
doesn't mean I don't appreciate a developed brain and a good vocabulary.
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Quoting flsky:

Implications of this?


you can see if you have any broken bones easier?
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Quoting CyclonicVoyage:


You should add this as well.

L. Eye Character: Open in the southwest


I wonder if that is some manifestation of some westerly vertical shear beginning. It seems that Tomas has been gradually struggling to keep its eye wall closed on its south and west sides for the last several hours.
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Quoting NCHurricane2009:
I saw that episode of stormchasers too! What was the date the yazoo city tornado hit?


april 24, 2010
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1229. flsky
Quoting JFLORIDA:
The sun has been ramping up in X ray activity over the last few hours.

Its getting rather impressive:



Implications of this?
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1228. DDR
Tomas's feeder band is over North east Trinidad and Tobago,has been bring heavy rain to the area for at least 2 hours,serious flooding may be taking place right now,
Radar..Link
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Quoting VAbeachhurricanes:


Don't use big words, it makes you sound educated ;)


LOL

Actually, I considered toning it down a tad just in case my warped idea of "clarification" made flsky even more confused.
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Quoting Grothar:
Just a few more mph to a cat 3


Yep, so close yet so far. Environmental conditions in the upper-layers of the atm. may slow down Tomas's intensification. I do think its possible for Tomas to get cat. 3 later today, but its possible also that it get stuck at cat. 2.
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Quoting alfabob:
M. Eye Shape & Diameter: Circular with a diameter of 20 nautical miles (23 statute miles)

Remarks Section - Additional Remarks...
FREQUENT LIGHTING IN NE EYEWALL NEAR CENTER


You should add this as well.

L. Eye Character: Open in the southwest
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Quoting KoritheMan:


I was echoing what you said. Namely, that worrying is tantamount to concern. A subset of it, if you will. A corollary. ;)


Don't use big words, it makes you sound educated ;)
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Quoting Krycek1984:


Chavez lets people on the internet/?


Remember that there is an opposition in Venezuela.... Chavez is just beginning to impose Socialism / Tyrany there.... Many people still have internet, cellulars and modern tech...
Member Since: August 2, 2010 Posts: 21 Comments: 9690
I saw that episode of stormchasers too! What was the date the yazoo city tornado hit?
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1220. Grenada
Quoting flsky:

No, I'm sorry. It's late. I thought I saw something in the tail going south. I think it must have been cloud tops.



It does appear to be carrying a sting!

Member Since: August 21, 2010 Posts: 0 Comments: 96
Quoting flsky:

I don't know what you mean.


I was echoing what you said. Namely, that worrying is tantamount to concern. A subset of it, if you will. A corollary. ;)
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Quoting VAbeachhurricanes:


remember we were all watching on here as that tornado went through yazoo city? That episode was on stormchasers last week... it was really sad, and hit home...


Actually, I just came back from a trip to that very area about a week ago. Surprisingly, the city itself, even downtown, is practically unscathed. The only noticeable damage was in the woods on the outskirts of town, and in the general vicinity. What damage I did see though, was stunning.
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1217. Grenada
Quoting flsky:

I imagine "worrying" is an element of "caring."



Who can help but worry about Haiti and it's people, no one wants Tomas on their doorstep but for it to reach Haiti would be unbearable.
Member Since: August 21, 2010 Posts: 0 Comments: 96
1216. flsky
Quoting KoritheMan:


This.

I don't know what you mean.
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Quoting tornadodude:


thats true,

I actually got to meet Reed Timmer and check out the chasing vehicles back in May, was pretty awesome


remember we were all watching on here as that tornado went through yazoo city? That episode was on stormchasers last week... it was really sad, and hit home...
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1214. flsky
Quoting sunlinepr:




Small blob called Thomas??

No, I'm sorry. It's late. I thought I saw something in the tail going south. I think it must have been cloud tops.
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Quoting flsky:

I imagine "worrying" is an element of "caring."


This.
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1212. flsky
Quoting Krycek1984:


If it happens, it happens. It's very sad but there's nothing we can do about it. Sitting here worrying about it doesn't do any good. The most we can do is extend our prayers, extend our wallets, and hope for the best.

I imagine "worrying" is an element of "caring."
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Quoting Krycek1984:


Chavez lets people on the internet/?


Apparently.

That, or my original hunch was correct.
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Yesterday, I also summarized the crazy October weather we've had, linking the 954 mb historic storm over the central US to the tropical weather in the Atlantic.

Link to that blog post here.
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Latest Tomas analysis for you late-nighters/early-morningers. Very detailed, I've gotten positive commentary on the way I did the analysis on Richard. Hopefully, you enjoy this Tomas discussion as well,

Link to post here.
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Quoting tornadodude:


yeah, ive seen a couple of them
"Twister" was on TBS tonight...couldn't help but watch a little.
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Quoting sunlinepr:


Have you seen live tornados??.... Here in PR I've only seen water spouts in diffrent coastal areas....


yeah, ive seen a couple of them
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Quoting sunlinepr:
Before I go to sleep, Think for a moment....

Thousands of people living on improvised Blue tent shelters. How would they be able to cope with 100 mph plus winds???? Can you imagine yourself with your wife and kids there??? Man, I hope that this is not happening....


If it happens, it happens. It's very sad but there's nothing we can do about it. Sitting here worrying about it doesn't do any good. The most we can do is extend our prayers, extend our wallets, and hope for the best.
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05:37:00Z 13.933N 62.450W
SFMR
85 knots
(~ 97.7 mph)
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Quoting KoritheMan:


You guys should get away with only some gusty winds and some heavy rainfall. Remember, the weakest quadrants of hurricanes are the southern and western ends. You'll be on the south side, where it's not as bad.


Chavez lets people on the internet/?
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Before I go to sleep, Think for a moment....

Thousands of people living on improvised Blue tent shelters. How would they be able to cope with 100 mph plus winds???? Can you imagine yourself with your wife and kids there??? Man, I hope that this is not happening....
Member Since: August 2, 2010 Posts: 21 Comments: 9690
1201. Grothar
Just a few more mph to a cat 3
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1200. Grothar
WTNT31 KNHC 310556
TCPAT1
BULLETIN
HURRICANE TOMAS INTERMEDIATE ADVISORY NUMBER 8A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL212010
200 AM AST SUN OCT 31 2010

...HURRICANE HUNTER AIRCRAFT FINDS TOMAS A LITTLE STRONGER...


SUMMARY OF 200 AM AST...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...13.8N 62.4W
ABOUT 90 MI...140 KM WNW OF ST. VINCENT
ABOUT 95 MI...150 KM W OF ST. LUCIA
MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/HR
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 8 MPH...13 KM/HR
MINIMUM CENTRAL PRESSURE...982 MB...29.00 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

THE GOVERNMENT OF TRINIDAD AND TOBAGO DISCONTINUED THE TROPICAL
STORM WARNING FOR TOBAGO AND GRENADA AT MIDNIGHT AST.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* DOMINICA
* MARTINIQUE
* ST. LUCIA
* ST. VINCENT AND THE GRENADINES

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 200 AM AST...0600 UTC...THE CENTER OF HURRICANE TOMAS WAS
LOCATED BY AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT NEAR
LATITUDE 13.8 NORTH...LONGITUDE 62.4 WEST. TOMAS IS MOVING TOWARD
THE WEST-NORTHWEST NEAR 8 MPH...13 KM/HR...AND THIS GENERAL MOTION
IS EXPECTED TO CONTINUE THROUGH SUNDAY NIGHT...FOLLOWED BY A TURN
TOWARD THE WEST ON MONDAY. ON THE FORECAST TRACK...THE CENTER OF
TOMAS WILL CONTINUE MOVING AWAY FROM THE WINDWARD ISLANDS
OVERNIGHT.

DATA FROM THE HURRICANE HUNTER AIRCRAFT INDICATE THAT MAXIMUM
SUSTAINED WINDS HAVE INCREASED TO NEAR 100 MPH...155 KM/HR...WITH
HIGHER GUSTS. TOMAS IS A CATEGORY TWO HURRICANE ON THE
SAFFIR-SIMPSON HURRICANE WIND SCALE. SOME STRENGTHENING IS
FORECAST DURING THE NEXT 48 HOURS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 50 MILES...85 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 175
MILES...280 KM. IN THE PAST HOUR A WIND GUST TO 48 MPH...78 KM/HR
...WAS REPORTED ON MARTINIQUE.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB...29.00 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE STILL OCCURRING ON THE
ISLANDS WITHIN THE WARNING AREA...AND ARE EXPECTED TO CONTINUE
THROUGH SUNDAY MORNING.

RAINFALL...TOMAS IS EXPECTED TO PRODUCE ADDITIONAL RAIN
ACCUMULATIONS OF 2 TO 3 INCHES ACROSS PORTIONS OF THE WINDWARD AND
SOUTHERN LEEWARD ISLANDS THROUGH SUNDAY. ISOLATED MAXIMUM STORM
TOTAL AMOUNTS OF 8 INCHES ARE POSSIBLE IN ASSOCIATION WITH TOMAS.

STORM SURGE...LARGE AND POTENTIALLY DESTRUCTIVE WAVES ARE STILL
POSSIBLE...BUT WATER LEVELS WITHIN THE WARNING AREA WILL CONTINUE TO
DIMINISH OVERNIGHT.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 AM AST.

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Quoting serialteg:


well its not nine feet i saw the contest 6ft with choppy conditions...


The bad thing about the SE (Inches/Califa/Chanel) is that they always sponsor events in the NW area... Inches is going to be Offshore due to Thomas....

Bedtime...
Member Since: August 2, 2010 Posts: 21 Comments: 9690
Quoting sunlinepr:


You have 9.1 feet in the Middles area, although the wind is from NW, not offshore, but any how... Think Rincon or Aguadilla would be a better place to move that contest... (Wildo or Domes)

Link


well its not nine feet i saw the contest 6ft with choppy conditions...
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Quoting serialteg:
8ft surf called for tomorrow in south PR with kelly slater and the irons brothers in the north shore. such a shame


You have 9.1 feet in the Middles area, although the wind is from NW, not offshore, but any how... Think Rincon would be a better place to move that contest... (Marias or Domes)

Link
Member Since: August 2, 2010 Posts: 21 Comments: 9690

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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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