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: 293 - 243

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

Quoting Hurricanes101:
Why would anyone with any sort of backbone want this to hit Haiti?

The nerve of some people


Kind of sad. I have friends, Pastors, and evangelists, and even Michael W. Smith (famous Christian pop singer) who goes there many times to help cure people and cleanup from the destruction that has unfold this year. They don't need this, I hope it slides west of Haiti and east of Cuba, in that gap, then head out to sea. That would be the best scenario knowing that Tomas will most likely not weaken.
Member Since: Posts: Comments:
Quoting Hurricanes101:
Well crap this isnt hitting Florida?

Why even track this storm then?

*Leaves*


LOL
Member Since: Posts: Comments:
Impressive. Multiple intense updrafts occurring around the eye.

Member Since: Posts: Comments:
Quoting GBguy88:


I know, I just thought it was odd for someone to make a comment saying that they'd rather a hurricane hit Haiti than Florida given the current state of things.


Oh ok, that is a horrible thing to say, we must be careful what we post, I hope nobody actually means that...
Member Since: Posts: Comments:
Well crap this isnt hitting Florida?

Why even track this storm then?

*Leaves*
Member Since: Posts: Comments:
Quoting Jedkins01:


The chance of Tomas hitting Florida is about the same as an earthquake lol, not impossible, but very unlikely indeed.


I know, I just thought it was odd for someone to make a comment saying that they'd rather a hurricane hit Haiti than Florida given the current state of things.
Member Since: Posts: Comments:
Quoting cat5hurricane:

Tomas isn't going anywhere near FL.


how do you know that?
Member Since: Posts: Comments:
Quoting tropicfreak:


Sure lets wish a cat 3 hurricane on an earthquake-stricken nation.


I'm not wishing a storm on them at all.
Member Since: Posts: Comments:
Quoting GBguy88:


Given that Florida hasn't had any major earthquakes lately, I think we'd actually be a little better equipped for a hurricane...but that's a matter of opinion I suppose.


The chance of Tomas hitting Florida is about the same as an earthquake lol, not impossible, but very unlikely indeed.
Member Since: Posts: Comments:
Quoting Neapolitan:

Ummm...what?


Sure lets wish a cat 3 hurricane on an earthquake-stricken nation.
Member Since: Posts: Comments:
Quoting GBguy88:


Given that Florida hasn't had any major earthquakes lately, I think we'd actually be a little better equipped for a hurricane...but that's a matter of opinion I suppose.


Yeah, but we still don't need a hurricane here. The election season has been rough enough on us with all those TV ads!
Member Since: Posts: Comments:
Quoting Cazatormentas:
Hi, folks! Just writing from Spain.

Have you noticed the eye of TOMAS is smaller than before? Just a good sign of progresive strenghtening. Compare:

16 UTC:


18 UTC:


In the other hand, TOMAS has stayed in the same place at least since the last two hours, just looking at these images.

We are monitoring the ciclone in Cazatormentas (Spanish Weather Enthusiasts Site)


A well developed Hurricane, so teh IR looks a bit sick, but the visible gets better in each frame, as well as the radar. Tomas is slowly intensifying.
Member Since: Posts: Comments:
Why would anyone with any sort of backbone want this to hit Haiti?

The nerve of some people
Member Since: Posts: Comments:
Quoting Neapolitan:

Ummm...what?


That's strange, you cut off most of my quote.
Member Since: Posts: Comments:
Quoting tropicfreak:


We haven't ruled out a FL hit. The NHC is thinking that the ridge of High pressure to its north will keep it on a general WNW track, keeping it away from Hati, but after it slams Jamaica, then only God knows what will happen.


A FL hit would be an extreme outside chance, but not worth mentioning at all, unless Tomas defies steering currents somehow in the long term.
Member Since: Posts: Comments:
Quoting CaneWarning:


Dr. Masters said it should hit Haiti. I hope he is right and it stays away from Florida. Did something change since his update?


Given that Florida hasn't had any major earthquakes lately, I think we'd actually be a little better equipped for a hurricane...but that's a matter of opinion I suppose.
Member Since: Posts: Comments:
It also appears that the East Pacific hurricane season is over...
Member Since: Posts: Comments:
I didn't expect Shary to become a Hurricane, but strange things are happening this year, so I guess it wasn't too much unexpected for me. I expect Tomas to slowly strengthen or hold steady on intensification for the next 24-48 hours, until he reaches west of the islands.
Member Since: Posts: Comments:
Quoting CaneWarning:


Dr. Masters said it should hit Haiti. I hope he is right...

Ummm...what?
Member Since: Posts: Comments:
Hi, folks! Just writing from Spain.

Have you noticed the eye of TOMAS is smaller than before? Just a good sign of progresive strenghtening. Compare:

16 UTC:


18 UTC:


In the other hand, TOMAS has stayed in the same place at least since the last two hours, just looking at these images.

We are monitoring the ciclone in Cazatormentas (Spanish Weather Enthusiasts Site)
Member Since: Posts: Comments:
Quoting Levi32:


I see where you're coming from, but based on what I have seen, normal fluctuations don't usually produce outflow boundaries. Those are caused by pretty intense downdrafts that can only be caused by dry air entrainment. That said, dry air is certainly not a big problem for Tomas right now, and that is obvious because he continues to strengthen.


Hmm that's true, downdrafts that intense would support dry air mixing I guess, it may be just a relatively thin dry layer in the mid levels that undercut the convection, and then the convective process caused mixing of the dry air and then collapse.

I never quite thought of that...
Member Since: Posts: Comments:
Quoting cat5hurricane:
UL Divergence still very impressive with the Upper Level AC sitting right over him.



Divergence aloft lowers surface pressure. Considering the excellent divergence aloft, Tomas will likely be able to lower his surface pressure into the 980's by late this afternoon.
Member Since: Posts: Comments:
This storm has about 6-7 days of time to intensify while away from land, +1 more day of over water yet interacting with land during that time. This could get REALLY UGLY.
Member Since: Posts: Comments:
266. Relix
Man that NE turn worries me, especially at the speed its going.
Member Since: Posts: Comments:
Quoting CaneWarning:
Thank goodness this storm isn't coming to Florida!


We haven't ruled out a FL hit. The NHC is thinking that the ridge of High pressure to its north will keep it on a general WNW track, keeping it away from Hati, but after it slams Jamaica, then only God knows what will happen.
Member Since: Posts: Comments:
Looks like Tomas has slowed down. It's been right about to make landfall over St. Vincent for about 2 hours.

Radar loop.
Member Since: Posts: Comments:
Looks like some pretty intense cloudtops are appearing on the S side of the eye.
Member Since: Posts: Comments:
Just had a smattering of rain with a gentle breeze and spoke to someone in the North of Grenada who told me it had been raining this am but not much more so far. How lucky were we (this time)?

Stay safe all in St.Lucia and St. Vincent.

Member Since: Posts: Comments:
Quoting notverylikely:
The most worthless posts here do not come from the trolls. The most useless posts here are the ones that begin "As I said earlier" or "As I've been saying for three days" or any other manifestation of the "Look at me!!! See how smart I am?!?!?!" mentality of the amateur wannabes. Please go away. Your Great Leader has his own blog now.



Who is this "your great leader" junk?
Member Since: Posts: Comments:
Quoting Jedkins01:


Good points, I still am speculative based on my studies just because it sure seems like normal fluctuations without a dry air influence, however I could be wrong.


I see where you're coming from, but based on what I have seen, normal fluctuations don't usually produce outflow boundaries. Those are caused by pretty intense downdrafts that can only be caused by dry air entrainment. That said, dry air is certainly not a big problem for Tomas right now, and that is obvious because he continues to strengthen.
Member Since: Posts: Comments:
Quoting uncljbnd:
the word is MOOT

points are MOOT...not Mute.
mute is the button on your TV remote that shuts the sound off.




I wish I could do that to some around here, shut the sound off that is lol

oh wait I can *Ignore* lol

j/k
Member Since: Posts: Comments:
Quoting CaneWarning:
Thank goodness this storm isn't coming to Florida!


are you 100% sure??? 1000% sure??
Member Since: Posts: Comments:
Quoting Stormchaser2007:


NRL NAVY (Top)

RAMMB TC (Bottom)




Thanks so much! :)
Member Since: Posts: Comments:
Quoting goldmind:
http://weather.myfoxtampabay.com/maps/WTVT/custom/models/gfs_caribbean.html

not good, not good at all


That looks good to me.
Member Since: Posts: Comments:
Very obvious improvement of the eye structure being observed.

First radar image is at 17:00 UTC and the latest one is at 17:45 UTC. Pretty easy to see the eye contracting and becoming more circular.


Member Since: Posts: Comments:
Quoting Levi32:


Outflow boundaries are not always observed in developing storms, and they usually indicate dry air. Why do you think a thunderstorm would collapse that fast in a tropical cyclone? Even in weakening hurricanes, outflow boundaries are not always seen. The only time I have ever seen them was when dry air entrainment was an obvious problem. It's not a big problem here, but this is a massive storm for this time of year, and dry air is usually very abundant by the time it gets this late. Water vapor satellite imagery doesn't always tell you whether the air is thoroughly moist around the storm. It's highly likely that a circulation this large pulled in at least some dry parcels which caused the collapse of some cells on the western side. No other explanation fits the details as well. Outflow boundaries are caused by dry air.


Good points, I still am speculative based on my studies just because it sure seems like normal fluctuations without a dry air influence, however I could be wrong.
Member Since: Posts: Comments:
Quoting notverylikely:
The most worthless posts here do not come from the trolls. The most useless posts here are the ones that begin "As I said earlier" or "As I've been saying for three days" or any other manifestation of the "Look at me!!! See how smart I am?!?!?!" mentality of the amateur wannabes. Please go away. Your Great Leader has his own blog now.


...speaking of useless....
Member Since: Posts: Comments:
the word is MOOT

points are MOOT...not Mute.
mute is the button on your TV remote that shuts the sound off.


Member Since: Posts: Comments:
http://weather.myfoxtampabay.com/maps/WTVT/custom/models/gfs_caribbean.html

not good, not good at all
Member Since: Posts: Comments:

Viewing: 293 - 243

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.