Unprecedented Hurricane Tomas pounding the Lesser Antilles

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

Share this Blog
7
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 393 - 343

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35Blog Index

We lost the Hewanorra International Airport, Saint Lucia (Airport) weather station.

Does anyone have the wave forecast for the Netherland Antilles?
Member Since: Posts: Comments:

Member Since: Posts: Comments:
391. JRRP
Quoting TropicalMan2010:

near jamaica and stronger too wow

may be CAT 3
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:
How do you get GREarth??


Is Tyler working on that project?
Member Since: Posts: Comments:
Quoting Hurricanes101:
The structure of Tomas looks fine to me, it is trying to re-organize and is doing so successfully

It will look more symmetric once it closes off that eye

agreed
Member Since: Posts: Comments:
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.
Member Since: Posts: Comments:
Quoting GBguy88:


I was in Ivan's eyewall in the western Florida panhandle...that was bad enough.


You had tornadoes, we had them too although we read that there wasn't any but we 'know' there were.
Member Since: August 21, 2010 Posts: 0 Comments: 96
I feel sorry for the people of the lesser Antilles as this storm appears to be doing the nightmare scenario. Surprise intensification and then a stall. Hopefully it will not strengthen to much more before it decides to move on.looking at steering maps everyone has posted it looks like the currents are rather weak right now.
Member Since: Posts: Comments:
The structure of Tomas looks fine to me, it is trying to re-organize and is doing so successfully

It will look more symmetric once it closes off that eye
Member Since: Posts: Comments:
Tomas should become a Category 2 hurricane tomorrow, and a Major Hurricane Monday.
Member Since: Posts: Comments:
check out the steering in the 12Z ECMWF on day 10

basically the ECMWF has Tomas meander south of Jamaica for about 4 days, and then on day 10 take a look at the ridge to the north

Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting Hurricanes101:


I figured you would like that lol

I guess for me the best part of tracking is not really knowing where the storm will go

While the chances of a Florida hit are unlikely they are not impossible, I just hate seeing people say it won't hit here or there when it is just going through the Islands and will still be in the Caribbean 5 days from now.

Kind of takes the fun out of the chase for me




I understand what you're saying lol, I usually try to help people understand there's nothing to get excited about before anyone gets their hopes up that its worth really getting prepared for lol. I go absolutely nuts over weather myself, but Ive had too many times where I got hyped prematurely then had the wind knocked out of my sails a few days later. I figure I might as well help other people not experience the same! haha, plus, when you get too hyped, it always makes forecasting inaccurate. That is why I hold myself back before I really get ramped up about a storm haha
Member Since: Posts: Comments:
Quoting Stormchaser2007:
Overall structure looks ragged.



At least from yesterday when he was still a TS.
Member Since: Posts: Comments:
FULL IMAGE

Member Since: Posts: Comments:
Hey guys,

If there is anyone close to my area (Indiana, Illinois, Ohio, Michigan, Kentucky) who would like to make a tornado chasing team, send me a personal message, and we can see what happens.

I have finally acquired a van for chasing, and would like others to join me who are close by, should be a good time.

thanks! (:

matt
Member Since: Posts: Comments:

Quoting TropicalAnalystwx13:


Oh...I do.

Any idea when its actually coming out?


It's already out for purchase.

1-year subs only for now.

Go to the owners forum to get the link to purchase it.
Member Since: Posts: Comments:
Quoting Hurricanes101:


Doesnt it always? lol

Pretty much. Thought it'd be worth saying though ;)
Member Since: Posts: Comments:
Quoting JRRP:

near jamaica and stronger too wow
Member Since: Posts: Comments:
Quoting Stormchaser2007:


You have email Mike and request a trial.

You have to own a GR product though.


Oh...I do.

Any idea when its actually coming out?
Member Since: Posts: Comments:


Click link for animation:

Link
Member Since: Posts: Comments:
btw it got down 53 degrees this morning lowest temp this fall/winter
Member Since: Posts: Comments:
strong rains in south PR not related to tomas? windy too
Member Since: Posts: Comments:
More of the vertical uplifting should begin to occur on his northern semicircle and begin to wrap around the western edge of the eyewall where's there currently a convective void. Dry air will continue to filter out and no longer be an impediment.

Click For Animation
Member Since: Posts: Comments:

Quoting TropicalAnalystwx13:
How do you get GREarth??

You have email Mike and request a trial.

You have to own a GR product though.
Member Since: Posts: Comments:
Quoting Grenada:



Ivan over Grenada


I was in Ivan's eyewall in the western Florida panhandle...that was bad enough.
Member Since: Posts: Comments:
367. JRRP
Member Since: Posts: Comments:
366. SLU
Quoting GBguy88:


I can't imagine what it'll be like if it continues to strengthen and move very little...a slight jog to the north, and the strong portion of the eyewall is going to be right over St. Lucia. If the storm doesn't start moving, they could be subject to that eyewall for several hours...that's pretty scary, especially given the potential for intensification. Even Cat 1 winds can do a lot of damage if they're on you for that long.


Yeh. There is a lot of damage already. Especially in the south and east of the island. The main road from the north to the south of the island has been cut off by fallen trees, poles and landslides.
Member Since: July 13, 2006 Posts: 13 Comments: 5354
How do you get GREarth??
Member Since: Posts: Comments:
Dynamic models:



GFS Ensemble models

Member Since: Posts: Comments:
Quoting cat5hurricane:

Either way, I think we can probably both agree that timing is going to mean a lot down the road.


Doesnt it always? lol
Member Since: Posts: Comments:
Quoting Stormchaser2007:
Overall structure looks ragged.




Nice cloudtops though rapping the entire circulation. Looks like its filtering out the dry air.
Member Since: Posts: Comments:
ughh give it time it'll fix itself
Member Since: Posts: Comments:
Quoting Stormchaser2007:
Overall structure looks ragged.


It has improved throughout the day though.
Member Since: Posts: Comments:
Quoting kmanislander:


If you look at the image I posted just now you will see that there is a weakness left over from Shary departing to the NE. Thomas is being " handed off " from the ridge to the East of that weakness that has been steering him to the ridge coming from the GOM that is taking over the steering.

The flow has therefore weakened even though it is still strong enough to prevent Tomas heading up into the weakness. He may accelerate later in the period once the high from the GOM gets positioned more overhead than where it is now.

As the ridge begins to move into the GOM, I agree, accelerating should begin.
Member Since: Posts: Comments:
Overall structure looks ragged.


Member Since: Posts: Comments:
St Lucia is really getting pounded.
Member Since: Posts: Comments:
Have to run out now. Back later.
Member Since: Posts: Comments:
Very strong convection building around the center.

Member Since: Posts: Comments:
Quoting GBguy88:


It just sparked my curiosity, because all the hurricanes I've been through have been the classic weaken-after-landfall scenario...I'm just trying to imagine what it would be like to have a slow moving hurricane rapidly intensify over top of you. Not saying it's rapidly intensifying just now, but it's a scary thought.



Ivan over Grenada
Member Since: August 21, 2010 Posts: 0 Comments: 96
Complete Update



AOI
AOI AOI AOI

AOI AOI AOI

TS BUSTED FORECAST ALIBI
Member Since: Posts: Comments:
Quoting serialteg:


hey,

whats that about a mid range high making it miss that obvious steering weakness thus explaning the wnw track from the nhc and models?


Tomas is not going into that weakness. See my post 349
Member Since: Posts: Comments:
Quoting Hurricanes101:


I would think in this scenario that the faster Tomas gets to the western edge of the ridge in the Caribbean the more likely he will turn north

The slowing down of Tomas now is not a good thing for ares further west

Either way, I think we can probably both agree that timing is going to mean a lot down the road.
Member Since: Posts: Comments:
350. JRRP
GFDL
Link

HWRF
Link
Member Since: Posts: Comments:
Quoting cat5hurricane:

Thanks Kmanislander. What are your thoughts in regards to his recent slowdown?


If you look at the image I posted just now you will see that there is a weakness left over from Shary departing to the NE. Thomas is being " handed off " from the ridge to the East of that weakness that has been steering him to the ridge coming from the GOM that is taking over the steering.

The flow has therefore weakened even though it is still strong enough to prevent Tomas heading up into the weakness. He may accelerate later in the period once the high from the GOM gets positioned more overhead than where it is now.
Member Since: Posts: Comments:
348. Relix
Quoting serialteg:


how about it hittin water dude... wth

:P

gonna raise the prices in the market?

mira voy pa la metro... ima be in SJ tonite


I will be in the Circotic party =P. Gotta enjoy before the storm comes haha
Member Since: Posts: Comments:
Quoting kmanislander:


Good afternoon

Here is the correct steering layer for Tomas. Note the pressure range at the bottom right of the image.



hey,

whats that about a mid range high making it miss that obvious steering weakness thus explaning the wnw track from the nhc and models?
Member Since: Posts: Comments:
Quoting SLU:


Well to be honest with you. The country wasn't adequately warned primarily as a result of the system's rapid overnight burst of intensification. And of course, some persons totally downplayed the severity of the situation as usual and went about their normal daily activities this morning.

It is now becoming a major disaster now given the lack of preparation and the strength of the winds which have caused some damage already. The worst is about to strike the island and the system has also suddenly stalled over the last few hours which means that there's going to by a mighty pounding from this strengthening hurricane.

This could be the worst disaster in St. Lucia since Major Hurricane Allen in 1980 based on reports coming through.


I can't imagine what it'll be like if it continues to strengthen and move very little...a slight jog to the north, and the strong portion of the eyewall is going to be right over St. Lucia. If the storm doesn't start moving, they could be subject to that eyewall for several hours...that's pretty scary, especially given the potential for intensification. Even Cat 1 winds can do a lot of damage if they're on you for that long.
Member Since: Posts: Comments:
Quoting cat5hurricane:

If he slows down considerably later in the track, then he'll have a better chance to catch it I think. A faster track would seem to mean he would sneak under the inbound trough and take advantage of the ridge's steering when it's the strongest before it's possibly eroded by the longwave. Timing is everything.


I would think in this scenario that the faster Tomas gets to the western edge of the ridge in the Caribbean the more likely he will turn north

The slowing down of Tomas now is not a good thing for areas further west
Member Since: Posts: Comments:
Quoting Relix:


The problem is it gives more time for the front to come down and pick it up. I am all for it hitting PR than going over Haiti. So many thousands of lives lost.


how about it hittin water dude... wth

:P

gonna raise the prices in the market?

mira voy pa la metro... ima be in SJ tonite
Member Since: Posts: Comments:
Quoting kmanislander:


Good afternoon

Here is the correct steering layer for Tomas. Note the pressure range at the bottom right of the image.


Thanks Kmanislander. What are your thoughts in regards to his recent slowdown?
Member Since: Posts: Comments:

Viewing: 393 - 343

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Overcast
52 °F
Overcast