Rains abate in Haiti as Tomas weakens

By: Dr. Jeff Masters , 8:24 PM GMT on November 05, 2010

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Data from this afternoon's flight by the Hurricane Hunters shows that Tomas may have weakened to a tropical storm, though NHC is maintaining it as a hurricane in their 5pm advisory. The 3:28pm center fix found that Tomas' pressure had risen to 992 mb, and the top surface winds seen by the SFMR instrument were 64 mph. Highest winds at 10,000 feet were 74 mph, supporting reducing Tomas' status from hurricane to tropical storm--though it is possible that the aircraft did not sample the strongest winds of Tomas. The Gran Piedra, Cuba radar shows fewer echoes than this morning, and satellite loops also reveal a weakened storm, with much less heavy thunderstorm activity near the center. The weakening was probably due to the fact the center of Tomas passed very close to the rugged terrain of Haiti's southwest peninsula, and the rough mountains disrupted the flow into the developing eyewall of the hurricane. Conditions remain favorable for intensification, though, with wind shear a moderate 10 - 20 knots, and SSTs a very warm 29.5°C.


Figure 1. Visible MODIS satellite image taken by NASA's Terra satellite at 11:30am EDT November 5, 2010. image credit: NASA.

Impact on Hispaniola and Cuba
A trough of low pressure over the Eastern U.S. is drawing Tomas northeastward at 12 mph, and this forward speed will gradually increase to 15 mph by early Saturday morning. Tropical storm force winds of 39+ mph extend out about 140 miles to the east, and Tomas is probably bringing tropical storm force winds to the tip of eastern Cuba and Haiti's northwest peninsula at present. Rainfall is the primary concern from Tomas, though, not wind. Satellite estimates (Figure 2) indicate that Tomas dumped up to 4 - 6 inches of rain as of 8am EDT on much of southen Haiti; an additional 1 - 3 inches has probably fallen since then. However, the band of heavy rain to the south of Haiti that appeared poised to give southern Haiti an additional 3 - 6 inches of rain today got disrupted when Tomas' center brushed the mountainous tip of southwest Haiti. Thus, it appears the worst of the rain is over for Haiti. An additional 1 - 2 inches is possible in isolated regions, judging from recent satellite data. Preliminary news reports I've heard from Port-au-Prince indicate that the earthquake zone weathered the storm with no major loss of life. Severe flooding was reported on Haiti's southwest peninsula, with AP video showing 4 feet of water flowing through the streets of Leogane, 20 miles west of Port-au-Prince. It remains to be seen how the rest of Haiti fared, as satellite estimates of rainfall are often low, and do not properly measure the heavier rains that can fall in mountainous regions. A band of heavy rain is over the Dominican Republic this afternoon, and total rainfall amounts approaching ten inches in the mountains regions will likely cause dangerous flooding and mudslides in that country this afternoon and this evening.


Figure 2. Satellite-estimated rain amounts for the 24-hour period ending at 8am EDT Friday, November 5, 2010. Rainfall amounts of 4 - 6 inches (green colors) occurred over Costa Rica, the southwestern peninsula of Haiti, and isolated regions of the Dominican Republic and the rest of Haiti. Image credit: Navy Research Lab, Monterey.

Impact on the Southeast Bahamas and Turks and Caicos Islands
Although Tomas has been weakened by its close encounter with Haiti and now Cuba, the storm is in a favorable environment for re-intensification. I expect Tomas will re-intensify back to 85 mph winds by 2am EDT Saturday, as it passes through the Southeast Bahamas and Turks and Caicos Islands. Once Tomas pushes north of the islands on Sunday, the storm should weaken quickly, as wind shear is expected to rise to a very high 50 knots.

Tomas the second most damaging hurricane in St. Lucia history
Prime Minister Stephenson King announced yesterday that damage on the island of St.Lucia was $185 million--five times higher than earlier estimates. This sum is 19% of St. Lucia's GDP, and is the second most expensive hurricane ever for the island. Tomas damaged 10,000 homes and killed 14 people during its rampage over the island last Saturday. St. Lucia received the full brunt of the northern eyewall of Tomas as it intensified, and the St. Lucia weather service reported that sustained winds of 90 - 95 mph affected the island. Power has been restored to 90% of the island and most of the tourist facilities have reopened, however.

Tomas is the strongest hurricane to affect St. Lucia since Category 1 Hurricane Dean of 2007 brought 90 mph winds to the island. Dean killed one person and did $6.4 million in damage--0.5% of the nation's GDP. The island's strongest hurricane since accurate records began in 1851 was Hurricane Allen of 1980, which struck as a Category 3 hurricane with 130 mph winds. Allen killed 18 people on St.Lucia, and caused catastrophic damage of $235 million dollars ($613 million 2010 dollars.) This was 177% of the nation's GDP that year. The deadliest hurricane in St. Lucia history was the Category 5 Great Hurricane of 1780, which killed approximately 700 people. The Great Hurricane of 1780 was the Atlantic's deadliest hurricane of all-time, with 22,000 fatalities, mostly in the Lesser Antilles Islands.


Figure 3. Damage on St. Lucia from Hurricane Tomas. Image credit: St. Lucia Star.

Organizations Active in Haitian Relief Efforts:
Portlight disaster relief has shipped their mobile kitchen to Quisqueya, Haiti, and the kitchen will be ready to feed 500 people per day.
Lambi Fund of Haiti
Haiti Hope Fund
Catholic Relief Services of Haiti

Next update
I'll have an update Saturday morning.

My post on Haiti's hurricane history is now a permanent link in the "Articles of interest" section on our Tropical & Hurricane web page.

Jeff Masters

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Quoting WeatherfanPR:
Tomas at 5pm 20.3N 73.8W

and now Tomas at 8pm 20.4N 73.1W

moving east in the past 3 hours !!!

also weaker !!!

i agree, a slight jog to the ENE, that's better for the Turks and Caicos
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Quoting kimoskee:
How do you change your username? Is that allowed?
I wouldn't mind changing mine to reflect my location.
I don't know that u can. I'd suggest emailing support to find out one way or the other. But somehow I think u'd have to get a new account altogether to change your username...
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Puerto Rico Local Hurricane Tomas StatementLink
Blog Update
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[pats self on back]

Good call on the distance from Inagua.

CRS, I hope u don't get too much more than gentle rains...
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184. ta4u
Quoting alfabob:
Some spin associated with the blob at 32.5W, 10N; area by 47.5W, 10N also looks like a possible location for development. The first is most likely headed out to sea, the other possibly west into the Caribbean. Season still has a few weeks left.



At 1st glance, I saw a face: 2 eyes and a nose... lol
Is it because I am a newbie or the Martini effect?
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How do you change your username? Is that allowed?
I wouldn't mind changing mine to reflect my location.
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@JLPR, I wouldn't be surprised if that band hits PR, since Tomas is going that way [east].

That front passed through here around 4 p.m. today, with a marked decrease in humidity and temperature experienced. I expected a bit more rain with it, given the humidity of the airmass it was pushing against, but it's been dry so far. I'm starting to see where some models are coming from with the potential loop; there certainly seems to be a break in the voticity...
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HURRICANE TOMAS INTERMEDIATE ADVISORY NUMBER 31A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL212010
800 PM EDT FRI NOV 05 2010

...TOMAS MOVING NORTHEASTWARD TO THE SOUTH OF GREAT INAGUA ISLAND...
HEAVY RAINFALL CONTINUING OVER HISPANIOLA...


SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...20.4N 73.1W
ABOUT 135 MI...220 KM E OF GUANTANAMO CUBA
ABOUT 50 MI...80 KM S OF GREAT INAGUA ISLAND
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/HR
PRESENT MOVEMENT...NE OR 50 DEGREES AT 14 MPH...22 KM/HR
MINIMUM CENTRAL PRESSURE...994 MB...29.35 INCHES
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Quoting PRweathercenter:
Puerto Rico Hurricane Tomas Local Statement
Blog Update
the local weather is saying that he is going to move eastward, and certainly looks like is moving east now. But NHC is moving it NE, lets see what happened...
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Quoting WeatherfanPR:
I think that system over the central atlantic has no chance to move in the caribbean.

Why?
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Quoting BahaHurican:
I know what u mean... lol

So r u not going back to Oz? because if u do, u will need a new sign-in name... lol

Welcome to the "big" blog...

Actually i am soon but will be returning...so i'll keep the name for now...

I appreciate reading your comments, there's a lot a Floridawishcasters out there that forget we exist. We're not just a speed hump in the road!!!
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Tomas at 5pm 20.3N 73.8W

and now Tomas at 8pm 20.4N 73.1W

moving east in the past 3 hours !!!

also weaker !!!
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Quoting BahaHurican:
Looks like the center is only about 50 miles SW of Inagua now.
It looks so. Looks like conditions should be improving for Haiti and getting worse in T & C and southern Bahamas.
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Quoting BahaHurican:
Sure doesn't look as organized now as it did even two hours ago. It does also look like the centre's going to move a bit closer to Provo than the NHC track was suggesting :o(... not good for TCI...


very close or maybe just south of the TCI
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Quoting JLPR2:
I will be rather impressed if that band of convection reaches PR.


maybe not this one but other new ones
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Quoting WeatherfanPR:
I think Tomas is getting weaker and moving more easterly.
Agree, looks east to me, maybe a jog though...
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Quoting BahaHurican:
Sure doesn't look as organized now as it did even two hours ago. It does also look like the centre's going to move a bit closer to Provo than the NHC track was suggesting :o(... not good for TCI...


Evening....
First gentle rain showers just now started.

The nice thing about using the iPad is that I am lying flat in bed with it suspended flat above me. I had a long day.
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Quoting Stevebahamas:

I'm sorry my fellow Bahamian, even though i'm Australian, i'm on a small island and Crystals are limited... if you know what i mean???
I know what u mean... lol

So r u not going back to Oz? because if u do, u will need a new sign-in name... lol

Welcome to the "big" blog...
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169. JLPR2
I will be rather impressed if that band of convection reaches PR.
Member Since: September 4, 2007 Posts: 7 Comments: 8519
Quoting alfabob:


Yes, but the trough is north of Tomas right now; and there is a high pressure digging in from the NE. There should be more of a east component due to how the trough has developed; area adjacent to Tomas is pushing him more east then north. He may even end up doing a loop depending on how the high pressure moves.



...wow, different scenarios possible. Didn't think of that looping scenario. I guess now we have 3 possibilities on the table.

(1) Looping scenario like you mentioned
(2) Going straight NE than E as the NHC mentioned.
(3) Going NE, then hooking more NNE while it transitions into a baroclinically amplifying extratropical cyclone

Scenario 3 was sort of hinted at in the NHC 5 PM discussion:

THE HURRICANE IS CURRENTLY MOVING AT 35/12...PRIMARILY DUE TO THE
INFLUENCE OF COMBINED INFLUENCE OF A NORTH-SOUTH ORIENTED RIDGE TO
ITS EAST AND A VIGOROUS SHORT-WAVE TROUGH TO ITS NORTHWEST. THE
CYCLONE SHOULD CONTINUE TO MOVE NORTHEASTWARD AT ABOUT THE SAME
SPEED FOR ABOUT THE NEXT 36 H AND NEARLY ALL TRACK MODEL GUIDANCE
IS IN AGREEMENT WITH THIS. HOWEVER...BEYOND 36 H...THE MODEL SUITE
SHOWS A TREMENDOUS DIVERGENCE THAT FALLS INTO TWO FACTIONS. THE
NORTHERN GROUP...WITH MEMBERS AT FIVE DAYS JUST SOUTHEAST OF
NEWFOUNDLAND
...INCLUDE THE HWRF/GFDL/NOGAPS MODELS. THE ECMWF
LIKELY WOULD HAVE ALSO BEEN EXPLICITLY INCLUDED HERE...BUT IT
BECOMES ABSORBED BY A LARGE BAROCLINIC SYSTEM AFTER DAY THREE. THE
SOUTHERN GROUP...WITH MEMBERS AT FIVE DAYS JUST NORTH OF THE
CARIBBEAN...INCLUDE THE GFS/GFS ENSEMBLE/UKMET. THE FORECAST TRACK
CHOSEN LEANS MORE TOWARD THE LATTER BUNCH AND IS CONSIDERABLY SOUTH
OF THE MODEL CONSENSUS...WHICH IS AN UNREALISTIC PREDICTION...AND
SOMEWHAT SOUTH OF THE PREVIOUS ADVISORY. IT ALMOST GOES WITHOUT
SAYING...THE EXTENDED FORECAST OF THIS SYSTEM IS VERY UNCERTAIN.
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Quoting WeatherfanPR:
I think Tomas is getting weaker and moving more easterly.
Sure doesn't look as organized now as it did even two hours ago. It does also look like the centre's going to move a bit closer to Provo than the NHC track was suggesting :o(... not good for TCI...
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Quoting BahaHurican:
I object to this comment because it is not about the Bahamas.... lol

I'm sorry my fellow Bahamian, even though i'm Australian, i'm on a small island and Crystals are limited... if you know what i mean???
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164. JLPR2
But I guess that a nice looking blob in the middle of the ocean is neat to watch. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8519
I think that system over the central atlantic has no chance to move in the caribbean.
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Quoting JLPR2:


Yep, but even if it has managed to turn into a surface trough aided by the upper trough, wind shear is nowhere near favorable so I doubt we will see anything out of this.


Right on bro, thinking the same thing here.
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161. JLPR2
Quoting KEEPEROFTHEGATE:


You guys change time already? Dang it! I'll have to write that down to know when the TV programs will be. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8519
Quoting stormwatcherCI:
He is almost completely through the passage already. N of western Haiti.
Looks like the center is only about 50 miles SW of Inagua now.
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I think Tomas is getting weaker and moving more easterly.
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157. JLPR2
Quoting NCHurricane2009:


A tropical wave is a surface trough produced by the African Easterly Jet.

If it is not a wave, but rather a surface trough of some other sort, than there is only one other way to generate a surface trough. That would be through upper divergence. And the big mid-ocean upper trough is producing divergence over that area, so I guess the surface trough is a manifestation of the upper trough's divergence.


Yep, but even if it has managed to turn into a surface trough aided by the upper trough, wind shear is nowhere near favorable so I doubt we will see anything out of this.
Member Since: September 4, 2007 Posts: 7 Comments: 8519
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting NCHurricane2009:


I know Gonaives is notorious for getting mudslides. Anyone heard from there?


I saw that mentioned yesterday...will check and post it here if we come up with any info...
Member Since: August 13, 2007 Posts: 0 Comments: 10479
Quoting presslord:


we know Leogane was hammered....some reports that jacmel suffered flooding...maybe surge...Les Cayes was hit hard...
It's really sad that the same area which was so hard hit by the earthquake is now the hardest hit by Tomas... so far I've only heard 3 deaths. While I know it's unlikely that will end up being the death toll, I'm hoping the small early report will be indicative a small final count...
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Quoting presslord:


we know Leogane was hammered....some reports that jacmel suffered flooding...maybe surge...Les Cayes was hit hard...


I know Gonaives is notorious for getting mudslides. Anyone heard from there?
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Quoting NCHurricane2009:


I don't think so...Haven't the last several projected paths shown Tomas going thru the Windward Passage (west of Haiti, E of Cuba) as it is now?
He is almost completely through the passage already. N of western Haiti.
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Quoting JLPR2:


Not a tropical wave, it's a surface through.


A tropical wave is a surface trough produced by the African Easterly Jet.

If it is not a wave, but rather a surface trough of some other sort, than there is only one other way to generate a surface trough. That would be through upper divergence. And the big mid-ocean upper trough is producing divergence over that area, so I guess the surface trough is a manifestation of the upper trough's divergence.
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Quoting presslord:


Dude...my wife and kids remind me constantly that I ain't in charge o' nuttin'......

we're just workin' the phones, Tweets, etc, gettin' a picture of how Haiti has fared...lottsa rumors...some fact...


Been there.

Good luck getting things sorted out. It must be a chore.
Member Since: July 23, 2010 Posts: 1 Comments: 12414
Quoting Stevebahamas:
Is Crystal on the weather channel even qualified?????
who cares she's smoking hot...
I object to this comment because it is not about the Bahamas.... lol
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148. JLPR2
Quoting NCHurricane2009:


...THE ITCZ...

FROM THE COAST OF SIERRA LEONE NEAR 8N13W TO 8N18W 9N23W 8N30W
5N40W 5N50W...BECOMING INDISTINCT AFTER 5N50W. SCATTERED STRONG
RAINSHOWERS AND THUNDERSTORMS ARE FROM 7N TO 12N BETWEEN 33W AND
40W.
MODERATE RAINSHOWERS AND ISOLATED STRONG THUNDERSTORMS ARE
FROM 7N TO 10N BETWEEN 18W AND 21W...AND FROM 2N TO 8N BETWEEN
20W AND 30W. THE BASE OF AN UPPER LEVEL TROUGH IS NEAR 6N51W.
A SURFACE TROUGH IS 21N48W 13N49W. RAINSHOWERS AND THUNDERSTORMS
COVER THE ATLANTIC OCEAN FROM 6N TO 14N BETWEEN 45W AND 55W.
ANOTHER TROUGH IS NEARBY...ALONG 10N51W 15N54W.

I guess the ITCZ is helping it with surface convergence, but the discussion above doesn't mention tropical waves (complete discussion at this link)

By this time of year, tropical waves should be dying down. I wonder when the tropical wave machine typically stops working (what month/day?) Maybe, just maybe there is a tropical wave interacting with the upper trough producingn the convection.


Not a tropical wave, it's a surface through.
Member Since: September 4, 2007 Posts: 7 Comments: 8519
Quoting alfabob:
Is it just me or is Tomas headed east a lot sooner then predicted?





I don't think so...Haven't the last several projected paths shown Tomas going thru the Windward Passage (west of Haiti, E of Cuba) as it is now?
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Quoting BahaHurican:
So I wrote a brief blog entry on Tomas, if you want to read it. Also anybody who wants to post latest conditions etc. can feel free to do so.

And I am hoping CRS will be able to keep us posted overnight.


we know Leogane was hammered....some reports that jacmel suffered flooding...maybe surge...Les Cayes was hit hard...
Member Since: August 13, 2007 Posts: 0 Comments: 10479
Quoting PSLFLCaneVet:


It isn't thou? I am shocked. LOL. How goes it?


Dude...my wife and kids remind me constantly that I ain't in charge o' nuttin'......

we're just workin' the phones, Tweets, etc, gettin' a picture of how Haiti has fared...lottsa rumors...some fact...
Member Since: August 13, 2007 Posts: 0 Comments: 10479
So I wrote a brief blog entry on Tomas, if you want to read it. Also anybody who wants to post latest conditions etc. can feel free to do so.

And I am hoping CRS will be able to keep us posted overnight.
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Quoting JLPR2:


Not completely.


...THE ITCZ...

FROM THE COAST OF SIERRA LEONE NEAR 8N13W TO 8N18W 9N23W 8N30W
5N40W 5N50W...BECOMING INDISTINCT AFTER 5N50W. SCATTERED STRONG
RAINSHOWERS AND THUNDERSTORMS ARE FROM 7N TO 12N BETWEEN 33W AND
40W.
MODERATE RAINSHOWERS AND ISOLATED STRONG THUNDERSTORMS ARE
FROM 7N TO 10N BETWEEN 18W AND 21W...AND FROM 2N TO 8N BETWEEN
20W AND 30W. THE BASE OF AN UPPER LEVEL TROUGH IS NEAR 6N51W.
A SURFACE TROUGH IS 21N48W 13N49W. RAINSHOWERS AND THUNDERSTORMS
COVER THE ATLANTIC OCEAN FROM 6N TO 14N BETWEEN 45W AND 55W.
ANOTHER TROUGH IS NEARBY...ALONG 10N51W 15N54W.

I guess the ITCZ is helping it with surface convergence, but the discussion above doesn't mention tropical waves (complete discussion at this link)

By this time of year, tropical waves should be dying down. I wonder when the tropical wave machine typically stops working (what month/day?) Maybe, just maybe there is a tropical wave interacting with the upper trough producingn the convection.
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Quoting presslord:
OK...Who's in charge around here?!?!


It isn't thou? I am shocked. LOL. How goes it?
Member Since: July 23, 2010 Posts: 1 Comments: 12414
Tropical cyclone Jal

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Quoting KEEPEROFTHEGATE:
meth

lol

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Complete Update


AOI
AOI AOI AOI

AOI AOI AOI

TSPIN BUSTED FORECAST ALIBI
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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.