Dr. Jeff Masters' WunderBlog

Unprecedented Hurricane Tomas pounding the Lesser Antilles
Posted by: Dr. Jeff Masters, 3:38 PM GMT op 30 oktober 2010 +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
Categories: Hurricane
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1. 1900hurricane 3:42 PM GMT op 30 oktober 2010    
Thanks Dr. Masters for the update! The budding eyewall can also be seen on microwave:

Member Since: 2 augustus 2006 Posts: 43 Comments: 10456
2. Skyepony (Mod) 3:43 PM GMT op 30 oktober 2010    
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 30th day of the month at 15:37Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 300)
Storm Number & Year: 21L in 2010
Storm Name: Tomas (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 21
A. Time of Center Fix: 30th day of the month at 15:09:10Z
B. Center Fix Coordinates: 13°11'N 60°35'W (13.1833N 60.5833W)
B. Center Fix Location: 46 miles (74 km) to the E (92°) from Kingstown, Saint Vincent and the Grenadines.
C. Minimum Height at Standard Level: 3,037m (9,964ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 55kts (~ 63.3mph)
E. Location of the Estimated Maximum Surface Wind: 12 nautical miles (14 statute miles) to the N (353°) of center fix
F. Maximum Flight Level Wind Inbound: From 96° at 58kts (From the E at ~ 66.7mph)
G. Location of Maximum Flight Level Wind Inbound: 59 nautical miles (68 statute miles) to the NNE (15°) of center fix
H. Minimum Sea Level Pressure: 994mb (29.35 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 8°C (46°F) at a pressure alt. of 3,043m (9,984ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 13°C (55°F) at a pressure alt. of 3,046m (9,993ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 1°C (34°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 700mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 67kts (~ 77.1mph) in the north quadrant at 14:16:50Z
Maximum Flight Level Temp: 14°C (57°F) which was observed 11 nautical miles (13 statute miles) to the N (353°) from the flight level center
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3. Neapolitan 3:44 PM GMT op 30 oktober 2010    
"I expect that Tomas will strengthen to a Category 3 or 4 hurricane by Wednesday."

Incredible...
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4. MiamiHurricanes09 3:44 PM GMT op 30 oktober 2010    
Ragged eye beginning to appear to visible satellite imagery.

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5. SherwoodSpirit 3:44 PM GMT op 30 oktober 2010    
Thanks Dr. Masters.
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7. 1900hurricane 3:46 PM GMT op 30 oktober 2010    
Looks like the southern eyewall may be about to pop based on visible:

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9. AWeatherLover 3:46 PM GMT op 30 oktober 2010    
Wow! I'm in awe at how active a season it has already been.
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11. kmanislander 3:47 PM GMT op 30 oktober 2010    
It almost looks as if Tomas made a jog to the West to have the eye where it is now. Clearing out quickly.

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12. Skyepony (Mod) 3:48 PM GMT op 30 oktober 2010    
Jeff have a great trip home.. Wish we could keep you there. Your blogs from NHC have been excellent.
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13. weatherlover94 3:49 PM GMT op 30 oktober 2010    
Quoting MiamiHurricanes09:
Ragged eye beginning to appear to visible satellite imagery.



forming eye
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15. KEEPEROFTHEGATE (Mod) 3:50 PM GMT op 30 oktober 2010    
nice update doc and thank you for all that you do and for making the underground possible to do it on

thanks

KOTG
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16. sunlinepr 3:50 PM GMT op 30 oktober 2010    
Quoting goldmind:
Question - After thomas passes the leeward islands is gonna explode?


There's enough thermal energy compared to the Gom that has cooled down - to intensify...

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17. weatherlover94 3:52 PM GMT op 30 oktober 2010    
dr masters says cat 3-4 hurricane unbelievable for Nov and it will be Nov when it becomes a major
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18. zoomiami 3:52 PM GMT op 30 oktober 2010    
I think it is amazing that Dr. Masters was able to at the NHC while all this was going on. He will truly have a birds eye view of what they do, and that will be reflected in all of the updates to come.

However -- could you guys please wish this storm away?
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19. plywoodstatenative 3:52 PM GMT op 30 oktober 2010    
The end run of the models, is not good for Portlight or for Haiti in of itself. Whats the intensity forecast for that point in time?
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20. MiamiHurricanes09 3:52 PM GMT op 30 oktober 2010    
Quoting kmanislander:
It almost looks as if Tomas made a jog to the West to have the eye where it is now. Clearing out quickly.

Check out the large lower-level outflow boundary advecting westward out of the western semicircle.

Expect a convective wane over the next few hours.
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21. KEEPEROFTHEGATE (Mod) 3:53 PM GMT op 30 oktober 2010    
T.C.F.W
21L/H/T/C1
MARK
13.10n/60.33w
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22. weatherlover94 3:53 PM GMT op 30 oktober 2010    
i think we will be stronger that 75 at 2 pm
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23. kmanislander 3:54 PM GMT op 30 oktober 2010    
Quoting MiamiHurricanes09:
Check out the large lower-level outflow boundary advecting westward out of the western semicircle.

Expect a convective wane over the next few hours.


I noticed that, the entire West side. The system may be sufficiently well organized to shake that off though. Overall the circulation is looking impressive.
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24. kmanislander 3:55 PM GMT op 30 oktober 2010    
Out now until later today.
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25. plywoodstatenative 3:55 PM GMT op 30 oktober 2010    
What are the temps in the Caribbean basin right now running, along with a shear map if possible?

This is the worst time, financially, for any of us in South Florida. Between the snow birds coming down and the boat shows starting up, our economy does not need something like that in the Caribbean.
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26. KEEPEROFTHEGATE (Mod) 3:56 PM GMT op 30 oktober 2010    
Quoting zoomiami:
I think it is amazing that Dr. Masters was able to at the NHC while all this was going on. He will truly have a birds eye view of what they do, and that will be reflected in all of the updates to come.

However -- could you guys please wish this storm away?
sorry zoo this is going where it wants best advice save as many as you can if it heads to haiti
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27. unf97 3:57 PM GMT op 30 oktober 2010    
Dr. Masters, thank you very much for your updates from the National Hurricane Center. I have thoroughly enjoyed your updates from down there all week. I think it is great how you gave us insight as to how the NHC forecasters work through the complexities of forecasting these cyclones. Fascinating indeed.

Thanks again Doc!
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28. MiamiHurricanes09 3:57 PM GMT op 30 oktober 2010    
Quoting kmanislander:


I noticed that, the entire West side. The system may be sufficiently well organized to shake that off though. Overall the circulation is looking impressive.
That is true. The circulation has grown in vigor on satellite imagery. It will be interesting to see what happens with the convective structure though.
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29. scott39 3:58 PM GMT op 30 oktober 2010    
How far west in Longitude could Tomas possibly go?
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30. weatherlover94 4:02 PM GMT op 30 oktober 2010    
Quoting plywoodstatenative:
The end run of the models, is not good for Portlight or for Haiti in of itself. Whats the intensity forecast for that point in time?


i think it will go into cuba/Florida remember ivan? it was once suppost to go into Hati then into Cuba/Bahamas then Cuba/Florida then Cuba/Florida pan handle ended up hitting destin Fl as a cat 3 with winds 120 mph so take that with a grain of salt
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31. HurricaneSwirl 4:02 PM GMT op 30 oktober 2010    
2010 Atlantic Hurricane Season ACE so far: 148

5 more ACE until official hyperactive classification.
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32. weatherlover94 4:03 PM GMT op 30 oktober 2010    
Quoting kmanislander:
Out now until later today.


have a good saterday
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33. weatherlover94 4:04 PM GMT op 30 oktober 2010    
Quoting scott39:
How far west in Longitude could Tomas possibly go?


to the Yucatan peninsula or take the north turn and pull a charly type track or go north and hit hati
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34. Stormchaser2007 4:05 PM GMT op 30 oktober 2010    
Tomas should be able to push 2010's ACE into the "hyperactive" area.


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35. SLU 4:06 PM GMT op 30 oktober 2010    
Reports from St. Lucia:

- roofs being blown off
- lots of fallen trees
- power outages
- heavy rains
- tropical storm conditions
Member Since: 13 juli 2006 Posts: 11 Comments: 3055
36. HurricaneSwirl 4:06 PM GMT op 30 oktober 2010    
Quoting Stormchaser2007:
Tomas should be able to push 2010's ACE into the "hyperactive" area.




Yup.
Member Since: 7 juli 2008 Posts: 2 Comments: 3237
37. SLU 4:06 PM GMT op 30 oktober 2010    
Reports from St. Lucia:

- roofs being blown off
- lots of fallen trees
- power outages
- heavy rains
- tropical storm conditions
Member Since: 13 juli 2006 Posts: 11 Comments: 3055
38. AWeatherLover 4:06 PM GMT op 30 oktober 2010    
Quoting HurricaneSwirl:
2010 Atlantic Hurricane Season ACE so far: 148

5 more ACE until official hyperactive classification.


If Tomas remains at his current strength, how long would it take for him to add those 5 ACE?
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39. Stormchaser2007 4:06 PM GMT op 30 oktober 2010    
Large downdrafts exiting from the Western quadrant.

Convection should collapse soon.


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40. TerraNova 4:06 PM GMT op 30 oktober 2010    
Very humid column from 700 mb with slight stable air intrusion at the 850 mb level.

Barbados 12z sounding
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41. xcool 4:08 PM GMT op 30 oktober 2010    



Oct 30, 6:53 am



36 °F
slidell la
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42. xcool 4:09 PM GMT op 30 oktober 2010    
brb
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43. juniort 4:09 PM GMT op 30 oktober 2010    
I have not experienced anything like that so far in my life, I went through Ivan but this is worse, the wind was horrendous Thank God to be okay, my garage shed is gone have to be repaired...From Barbados
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45. hydrus 4:10 PM GMT op 30 oktober 2010    
Quoting SLU:
Reports from St. Lucia:

- roofs being blown off
- lots of fallen trees
- power outages
- heavy rains
- tropical storm conditions
Wow...
Member Since: 27 september 2007 Posts: 1 Comments: 14715
46. CosmicEvents 4:10 PM GMT op 30 oktober 2010    
Thank you Dr. Masters.
These reports from the "eye of the NHC" have been fascinating.
I love the fact that they still use the old fashioned paper plotting, using a protractor.
Viva low-tech!!!
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47. Bordonaro 4:10 PM GMT op 30 oktober 2010    
Quoting Stormchaser2007:
Large downdrafts exiting from the Western quadrant.

Convection should collapse soon.




Tell that to Tomas!
Link
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48. Stormchaser2007 4:12 PM GMT op 30 oktober 2010    
Pretty pronounced downdrafts.


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49. TerraNova 4:13 PM GMT op 30 oktober 2010    
Significant damage in St. Lucia according to 105.3 FM Caribbean Hot Radio>

Other stations streaming online here from all over the Caribbean, including St. Lucia, St. Vincent and Barbados.
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50. Thundercloud01221991 4:14 PM GMT op 30 oktober 2010    
what time does the next plane take off
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51. MiamiHurricanes09 4:16 PM GMT op 30 oktober 2010    
Quoting Stormchaser2007:
Pretty pronounced downdrafts.


Yep, I was just commenting on that. You can already start to see the beginning of the convective cloud tops warming on infrared (especially along the western semicicle of the eyewall).
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About JeffMasters
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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