Strengthening Tomas headed for the Lesser Antilles

By: Dr. Jeff Masters , 1:27 AM GMT on October 30, 2010

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Tropical Storm Tomas has exploded into existence in spectacular fashion, becoming the nineteenth named storm of this amazingly active 2010 Atlantic hurricane season. I'm reporting to you live from the National Hurricane Center tonight, where forecasters are working hard to stay abreast of Tomas' intensification. Three hurricane specialists are on duty tonight--Dave Roberts, who is handling Tropical Storm Shary, and Robbie Berg and Dan Brown, who are focusing on Tomas. The Hurricane Hunters have just left Tomas, as of 8pm EDT, and they found a significant increase in winds. Winds at their 1500 foot flight level were 70 mph, and surface winds as measured by the SFMR instrument were near 60 mph. This supports an increase in Tomas' winds to 60 mph in tonight's 8pm EDT public advisory. Since this is such a large increase in intensity from what was forecast--Tomas was not supposed to have 60 mph winds for another 24 hours--this necessitates issuance of a special advisory package. A full set of forecast maps, a marine advisory, wind probability forecast, and a discussion just went out to the world. While all this was occurring, several phone calls to Barbados, St. Lucia, and Martinique were made, alerting the islands to the fact that a Hurricane Warning may be required with the 11pm advisory tonight. NHC has both French speaking and Spanish speaking meteorologists on staff that can coordinate with the islands that don't have English as their main language. I listened in on a 5-minute conversation in French between the weather service in Martinique and NHC meteorologist Mike Tichacek, as they discussed when Martinique may want to issue a Hurricane Warning.


Figure 1. Warren VonWerne (right) of CARCAH presents the latest data from the Air Force Hurricane Hunters to hurricane specialist Robbie Berg.

Intensity forecast for Tomas
The forecasters at NHC are puzzling over the latest intensity forecasts for Tomas. The latest intensity forecast from the GFDL, HWRF, and SHIPS models are not that impressive, and they keep Tomas as a strong tropical storm or weak hurricane for the next five days. The wind shear forecast from SHIPS is particularly odd--the latest 18Z forecast predicts high wind shear of 20+ knots beginning Sunday morning, and the previous SHIPS forecast held wind shear below 15 knots for the next five days. The latest runs by the GFS, ECMWF, and UKMET models all show a very favorable environment for intensification over the next five days over the Caribbean, with Tomas positioning itself beneath an upper level high in a light wind shear environment. The best bet is that Tomas will intensify into a major hurricane over the Central Caribbean by early next week.


Figure 2. NHC meteorologist Mike Tichacek discusses the latest intensity forecast for Tomas with the Martinique weather service (in French.) In the background, hurricane specialist Dave Roberts works on advisories for Tropical Storm Shary.

Track forecast for Tomas
After Tomas reaches the central Caribbean 4 - 6 days from now, there are two possible track scenarios depicted by the models--a continued westerly motion towards Nicaragua, or a sharp turn to the north, with a track over Hispaniola or Puerto Rico. Steering currents will be weak, and we'll just have to wait and see how the steering currents evolve.

Tomas' formation location unprecedented this late in the season
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 formation of a tropical storm 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 (60°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 60°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 60°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 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.

Another unusual aspect of Tomas' formation is that we now have two simultaneous named storms in the Atlantic Ocean on October 29. There have been only four hurricane seasons since 1851 that have had two simultaneous named storms later in the year. 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.

Next update
I'll have more late Saturday morning.

Jeff Masters

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Quoting Neapolitan:

Good question. Another good one: which season has had so many TCs with no hurricane strikes on the lower 48 yet causing so much devastation elsewhere?
Probably the same one.
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Member Since: July 17, 2009 Posts: 71 Comments: 26848
2010's the 3rd most active hurricane season

1887 had 19-11-2, 1995 had 19-11-5, 2010 has 19-12-5.

I never thought we'd see this level of activity so soon after 2005.

And we still have a month to go, plus with the likelihood of a post-season storm I am thinking 2010 will end with Walter or Alpha
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Shear has been falling off ahead of Tomas which will further aid in the intensification process.

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724. HadesGodWyvern (Mod)
Tropical Cyclone Warning Center Perth
Tropical Cyclone Advice #3
TROPICAL LOW 01U
9:00 PM WST October 30 2010
======================================

At 8:00 pm WST, Tropical Low 01U (1002 hPa) located at 7.8S 95.6E or about 505 km north northwest of Cocos Island has 10 minute sustained winds of 30 knots with gusts of 45 knots. The low is reported as moving west southwest at 4 knots.

Dvorak Intensity: T3.0/3.0/D1.0/24HRS

The low is forecast to develop into a tropical cyclone early on Sunday. Although it is currently moving towards the west southwest, it is expected to take a southwards turn, and is likely to pass close to the Cocos Islands on Tuesday. Conditions are favorable for intensification and there is a significant risk that people on the Cocos Islands will experience VERY DESTRUCTIVE wind gusts.

Gales are not expected on the islands during Saturday or Sunday, but may develop during Monday as the system moves closer and intensifies. The period of greatest risk will commence on Monday evening, with the system likely to pass close to the islands during Tuesday.

Tropical Cyclone Watches
========================
A Cyclone WATCH continues for a developing tropical low for the Cocos (Keeling) Islands.

Forecast and Intensity
======================
12 HRS: 8.1S 94.8E - 45 knots (CAT 1)
24 HRS: 8.6S 94.7E - 55 knots (CAT 2)
48 HRS: 10.2S 96.1E - 80 knots (CAT 3)
72 HRS: 12.3S 96.6E - 80 knots (CAT 3)

Additional Information
=======================
Over the last six hours the system has consolidated with deep convection now beginning to wrap around the centre. High SSTs are likely assisting the low to overcome moderate shear.

A shear pattern consistently gives a DT of around T3.0. The MET is 3.0 based on a 24 hour trend of D. Pattern matching does not indicate any adjustment to the MET and hence both DT and MET are 3.0. There are no FT constraints to assigning 3.0 hence FT and CI are set at 3.0. The 0244Z ASCAT pass indicates 25-30 knots in the western semicircle, however given the previously reported low bias of ASCAT it is possible that winds in this region are 30-35 knots. The final wind intensity estimate is assigned at 30 knots. This system is considered to be very close to TC intensity and gales are likely to extend around the LLCC during the next diurnally favorable period overnight.

Shear conditions are forecast to become more favorable during Sunday and the system will remain over SST>28C. The mid latitude system passing to the south erodes the mid level ridge and results in a recurvature to the southeast during Sunday. This also brings the system into light shear and by Sunday evening the system should be experiencing quite favorable conditions. The development of the system in the South China Sea should not be detrimental to this system, so based on the expected conditions, and consistent with the trend in STIPS intensity guidance it is forecast to reach hurricane force on Monday.

The spread of model guidance indicates the Cocos Islands have a high risk of impact from hurricane force winds. As the system passes south of 12S the ocean heat content becomes marginal. The system is also likely to encounter more stable boundary layer air in the wake of the mid latitude system. Hence the system is expected to weaken as it moves off to the southwest on Wednesday.
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Quoting scott39:
Which season has had this many TCs, with no Hurricane strikes on the lower 48?

Good question. Another good one: which season has had so many TCs with no hurricane strikes on the lower 48 yet causing so much devastation elsewhere?
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Looks like we'll have a Halloween hurricane.

Last time that happened I think was Noel in 2007.
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Click For Animation
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Quoting Neapolitan:


Indeed. Too, only two previous seasons have recorded as many as 12 hurricanes: 1969 (which also had 12) and 2005, with the all-time record of 15.
Which season has had this many TCs, with no Hurricane strikes on the lower 48?
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Quoting Neapolitan:
That's 19-12-5 (on the way to 19-12-6), in case any of you are keeping score at home... ;-)

Gotta update the books. Still can't believe Shary made it. Incredible season. Day before Halloween and this type of activity going on. Wow.
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so will they go with the 70 knts that recon found?
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Quoting CybrTeddy:


Talk about an active season...


Indeed. Too, only two previous seasons have recorded as many as 12 hurricanes: 1969 (which also had 12) and 2005, with the all-time record of 15.
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Quoting CitikatzSouthFL:
kman, thanks soooo much for the "directionally challenged" chart. I can now put the degree heading with the directional heading and it makes is so much clearer in understanding the actual storm path. I have learned so much in this blog over the years....you all are DA BOMB! And good morning to all. Looks like the unusual and interesting season just keeps on going like the Energizer Bunny!LOL


You're welcome. It's the best compass rose I have found for tracking tropical systems.
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Thanks... I would be worried going to the DR in the next few days. Definetly watching where Tomas is going.
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SHIPS Shear Forecast for Tomas (12z):


TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
SHEAR (KT) 10 8 15 21 17 20 15 14 13 21 22 9 8
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Quoting TampaSpin:
Morning Kman.....And all!


I was hoping we wouldn't see one like Tomas this year. Virtually every system that has come up from that origin point has done a lot of damage along the way. One blessing is the TCHP has fallen off but not enough to prevent this becoming a major I am afraid.
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Quoting Neapolitan:
That's 19-12-5 (on the way to 19-12-6), in case any of you are keeping score at home... ;-)


Talk about an active season...
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Quoting Dakster:


Where's Puta Cana?


Hey my friend, is Punta Cana de "N" word is very important on that word, Punta Cana is in Dominican Republic.
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That's 19-12-5 (on the way to 19-12-6), in case any of you are keeping score at home... ;-)
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The trough that is to move Tomas out is on the West Coast now over California. Timing will be a real player here.
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Quoting miken62:
Headed to Punta Cana ..next week ....yay!!


Where's Puta Cana?
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kman, thanks soooo much for the "directionally challenged" chart. I can now put the degree heading with the directional heading and it makes is so much clearer in understanding the actual storm path. I have learned so much in this blog over the years....you all are DA BOMB! And good morning to all. Looks like the unusual and interesting season just keeps on going like the Energizer Bunny!LOL
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Member Since: August 17, 2010 Posts: 21 Comments: 6939
Morning Kman.....And all!
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From about an hour ago:


UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 30 OCT 2010 Time : 121500 UTC
Lat : 13:07:23 N Lon : 60:08:55 W


CI# /Pressure/ Vmax
3.6 / 992.6mb/ 57.0kt


Final T# Adj T# Raw T#
3.1 2.9 2.9

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -34.7C Cloud Region Temp : -50.4C

Scene Type : CURVED BAND with 0.50 ARC in LT GRAY
Maximum CURVED BAND with 0.56 ARC in LT GRAY
at Lat: 13:31:12 N Lon: 60:44:24 W

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : ON
Rapid Dissipation Flag : FLAG
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Two simultaneous hurricanes in late October.

AL, 21, 2010103012, , BEST, 0, 131N, 601W, 65, 993, HU,
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Hurricane Tomas
AL, 21, 2010103012, , BEST, 0, 131N, 601W, 65, 993, HU

19-12-5
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699. Mixed
Rain And Wind Starting To Pick Up Greatly Here In The North Of St Lucia
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Tomas
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Headed to Punta Cana ..next week ....yay!!
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Quoting hydrus:
Good morning K-Man..What your talking about shows up well on the MIMIC-TPW..Notice how well Tomas Massive spin looks..


Yeah, you can really see that high coming down from the NW
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No big surprise, but ATCF says Tomas is a hurricane; NHC should upgrade shortly:

NHC_ATCF
invest_al212010.invest
FSTDA
R
U
040
010
0000
201010301320
NONE
NOTIFY=ATRP
END
AL, 21, 2010103012, , BEST, 0, 131N, 601W, 65, 993, HU, 34, NEQ, 150, 80, 50, 90, 1009, 225, 20, 0, 0, L, 0, , 0, 0, TOMAS, M,
AL, 21, 2010103012, , BEST, 0, 131N, 601W, 65, 993, HU, 50, NEQ, 50, 25, 15, 40, 1009, 225, 20, 0, 0, L, 0, , 0, 0, TOMAS, M,
AL, 21, 2010103012, , BEST, 0, 131N, 601W, 65, 993, HU, 64, NEQ, 20, 15, 0, 0, 1009, 225, 20, 0, 0, L, 0, , 0, 0, TOMAS, M,
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694. P451


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Quoting kmanislander:


Looks that way but the pressure just came up 2 mbs. Probably upgrade at 11 if no further pressure rise and organization holds


Saw a 993 earlier, yesterdays recon showed 1001 mb but the NHC went the lower route.
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Quoting kmanislander:
The high over the GOM continues to press on to the East and the weakness in the steering caused by Shary is closing off quickly. The track of Tomas will respond to this by flattening out during the course of the next 18 hours to a more Westerly heading, say 280 to 290 degrees IMO.

Good morning K-Man..What your talking about shows up well on the MIMIC-TPW..Notice how well Tomas Massive spin looks..
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Quoting Orcasystems:


I never said it was going due west...I said it was due west of Barbados... its not tracking due west at all. Its tracking around 290-295



O mine, Some body was owned very hard, thanks Orca for the clarification.....
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From recon its a hurricane currently positioned due west of barbados and tracking at 290 WNW
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Quoting stormwatcherCI:
URNT12 KNHC 301301
VORTEX DATA MESSAGE AL212010
A. 30/12:31:30Z
B. 13 deg 07 min N
060 deg 12 min W
C. 700 mb 3044 m
D. 65 kt
E. 056 deg 18 nm
F. 143 deg 62 kt
G. 052 deg 28 nm
H. EXTRAP 995 mb
I. 9 C / 3047 m
J. 12 C / 3047 m
K. 2 C / NA
L. RAGGED
M. C50
N. 12345 / 7
O. 0.02 / 1 nm
P. AF300 0221A TOMAS OB 10
MAX FL WIND 66 KT E QUAD 11:47:10Z
SLP EXTRAP FROM DROPSONDE
NOT A SOLID EYEWALL FIXED CTR NEAR END OF A SPIRAL IN THE EYE AREA
MAX SFC WINDS WELL WITHIN THE RADAR CENTER
SONDE RELEASED NEAR MAX SFMR WINDS RECORDED 72 KTS AT SFC
;



Hurricane ?


Looks that way but the pressure just came up 2 mbs. Probably upgrade at 11 if no further pressure rise and organization holds
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Recon

P. AF300 0221A TOMAS OB 10
MAX FL WIND 66 KT E QUAD 11:47:10Z
SLP
EXTRAP FROM DROPSONDE
NOT A SOLID EYEWALL FIXED CTR NEAR END OF A
SPIRAL IN THE EYE AREA
MAX SFC WINDS WELL WITHIN THE RADAR CENTER
SONDE
RELEASED NEAR MAX SFMR WINDS RECORDED 72 KTS AT SFC




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Quoting kmanhurricaneman:
Orcasystems , i agree a due west movement


I never said it was going due west...I said it was due west of Barbados... its not tracking due west at all. Its tracking around 290-295
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686. SLU
Quoting stoormfury:
asdip what area in st lucia you are referring to. in the north heavy rain with gusts to 45mph


Morning Storm.

I heard that the winds are picking up. Gusts to 53mph and roofs blowing off in VF already. It's hard for me to be away from home in a time like this.
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Quoting Orcasystems:


I am not sure what you two are talking about... but the system is dead centre of the projected track, and has been since yesterday


I was responding to his statement regarding the models at the end of the runs, not what is happening now.
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Orcasystems , i agree a due west movement
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Quoting Gorty:


Much better but infrared Sat and normal Sat presntation doesnt look as good as the radar mainly at the center I am talking about. But based on reprts from tjose islands and the radar, I can see Tomas being Cat. 1 at 11:00 am. But he will take some time to get up to cat 3.
A Cat 1 at 11:00AM, Cat 2, as it passes South of PR, tomorrow around 2:00pm, and a Cat 3 Monday SE of Haiti as it makes the turn to E or ENE ....
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asdip what area in st lucia you are referring to. in the north heavy rain with gusts to 45mph
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Quoting kmanislander:


Typical when you have a late season system. Trying to forecast the track more than 24 to 48 hours out becomes a real challenge.


I am not sure what you two are talking about... but the system is dead centre of the projected track, and has been since yesterday
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yep
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Quoting Orcasystems:


The dropsonde/Observation reports are not displayed on the track, they are offset. The second Vortex run has not been plotted yet, but its due west.


Okay, will wait to see it. Not much distance between the two positions given the size of Barbados.
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Some people here need glasses.

http://www.meteo.fr/temps/domtom/antilles/pack-public/animation/animMOSAIC2.html


Radar again......:rolleyes.jpg:
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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.