Unprecedented Hurricane Tomas pounding the Lesser Antilles

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

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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

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Quoting MarcoIslandCat5:
if tomas gets to 80w/85w would he carry on heading west or is the north east hook stil in play?? thanks
florida pete


there is so much model spread right now the hurricane center is showing only a slight northward jog by Wednesday then the north east curve will be in question if you live in Florida watch this one until it starts the ne hook
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Quoting Levi32:


Supposedly not until 5:30am UTC, or 1:30am EDT.


Did they have to cancel the one for this afternoon?

There has not been a plane in Tomas since this morning
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HurricaneTomas's heading turned westward to (8.1degrees west of) WestNorthWest
from its previous heading of (3.7degrees west of) WestNorthWest
H.Tomas's average speed moving between its last 2 reported positions increased to ~9.3mph(~15km/h) from its previous travel speed of ~7mph(~11.3km/h)
TS.Thomas
29Oct 09pmGMT - 11.1n57.5w - 40mph(~64.4km/h) - . - 998mb - NHC.Adv.#1
30Oct 12amGMT - 11.6n57.6w - 60mph(~96.6km/h) - . - 999mb - NHC.Adv.#2
30Oct 03amGMT - 12.2n58.4w - 65mph(~104.5km/h) - - 997mb - NHC.Adv.#3
30Oct 06amGMT - 12.4n58.8w - 65mph(~104.5km/h) - - 997mb - NHC.Adv.#3A
30Oct 09amGMT - 12.9n59.5w - 70mph(~112.7km/h) - - 994mb - NHC.Adv.#4
30Oct 12pmGMT - 13.1n60.1w - 70mph(~112.7km/h) - - 993mb - NHC.Adv.#4A
H.Tomas
30Oct 03pmGMT - 13.3n60.7w - 75mph(~120.7km/h) - - 993mb - NHC.Adv.#5
30Oct 06pmGMT - 13.4n61.0w - 75mph(~120.7km/h) - - 992mb - NHC.Adv.#5A
30Oct 09pmGMT - 13.5n61.4w - 75mph(~120.7km/h) - - 992mb - NHC.Adv.#6

Copy&paste 11.1n57.5w, 11.6n57.6w, 12.2n58.4w, 12.4n58.8w, 12.9n59.5w-13.1n60.1w, 13.1n60.1w-13.3n60.7w, 13.3n60.7w-13.4n61.0w, 13.4n61.0w-13.5n61.4w, cfg, pos, 13.5n61.4w-18.4n87.8w into the GreatCircleMapper for a look at the headings and the distances traveled over the last 12^hours.

Using straightline projection upon the speed&heading averaged
over the 3hours spanning the last two reported positions:
~7days&22hours from now to RioHuach,QuintanaRoo,Mexico
after passing ~62miles(~99.8kilometres)south of Jamaica
(Copy&paste 13.4n61.0w-13.5n61.4w, 13.5n61.4w-16.954n77.741w, 17.854n77.741w-16.954n77.741w into the GreatCircleMapper if you wanna check)

^ The westernmost line-segment is the straightline projection.
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nevermind, thanks Levi lol
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Quoting Hurricanes101:
When is recon supposed to be back in Tomas??


Supposedly not until 5:30am UTC, or 1:30am EDT.
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Core structure is markedly improving now, with a convective bomb directly over the center and a recognizable eyewall now apparent in both radar and visible satellite imagery.



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I think the NHC has a good handle on Tomas so far, I see them using their expertise over model guidance with this one, though a blend of both thrown in, JMO.
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if tomas gets to 80w/85w would he carry on heading west or is the north east hook stil in play?? thanks
florida pete
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Quoting Floodman:


I know I don't need to tell you this (you're one of the old hands around here) but the track and intensity forecast accuracy rate goes up substantially in the 72-96 hour window; you'll know far better by this time tomorrow what you'll need to do, taking into account the fact that things can change very rapidly at times...
I know but still think by Tuesday should know whether we need to shutter up or not. In one way I hope not but then again for the sake of Haiti I would say I hope so. At least here we live in houses and don't have to expect to shelter in tents. I feel it for them and it's bad enough with a regular thunderstorm not to mention a potential major hurricane. More worried for my grand-daughter who is getting ready to start nursing school in Jamaica.
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Quoting stormwatcherCI:
I am here too and have decided if the turn has not begun by Tuesday to start shuttering up etc. Got a feeling he might come further west than currently projected due to the high uncertainty of the forecast path per NHC.


I sent Jim Cantore a tweet last night and was surprised when he personally replied, he said the Caymans are very much in play with Tomas.
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533. SLU
Quoting largeeyes:
SLU, what festival is this weekend in St. Lucia? I saw the fishing tournament..


It's the annual Creole Day Festival. It was actually supposed to take place tomorrow but it's been cancelled.

I just spoke to my brother in St. Lucia and he painted a picture of complete mayhem on the island. There is a powerful rain band moving across now and he said that those are the worst conditions he'd seen so far today.

I think the NHC's 75mph wind speed estimate is indeed too low based on what i'm hearing from St. Lucia. This is beginning to look more like a high-end cat 1 or even a low-end cat 2 hurricane.
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Quoting stormwatcherCI:
I am here too but in East End and have decided if the turn has not begun by Tuesday to start shuttering up etc. Got a feeling he might come further west than currently projected due to the high uncertainty of the forecast path per NHC.


I know I don't need to tell you this (you're one of the old hands around here) but the track and intensity forecast accuracy rate goes up substantially in the 72-96 hour window; you'll know far better by this time tomorrow what you'll need to do, taking into account the fact that things can change very rapidly at times...
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When is recon supposed to be back in Tomas??
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people were laughing at my character when it said the storm could be a major by tomorrow early this morning
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Quoting stormwatcherCI:
I am here too and have decided if the turn has not begun by Tuesday to start shuttering up etc. Got a feeling he might come further west than currently projected due to the high uncertainty of the forecast path per NHC.


I agree with you and think thats a good idea the forecast turns of systems so far this year by the models has not been too reliable. I work for a Boat maintenance company and we have over 100 boats to secure both in water and out big and small so we cant wait untill last minute to make the call it usually takes us 3 days.
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Tomas appears to be moving almost due west to me now and at a slower pace, also appears to be a convective burst over the center, wouldn't surprise me to see Tomas at 90-100mph by 11pm tonight.Also one thing to note Tomas sames to be a very destructive storm, everyone has their own personality, this one sames to have an Ivan like personality!
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darkness falls in the islands gonna be a long night for some
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Quoting Saltydogbwi1:


Evening Marco...I also live in Savannah Grand Cayman and we are watching this one closely no preparations being made yet but we tend to err on the side of caution since hurricane Ivan in 2004. Since Ivan everyone here is better prepared from the beginning of hurricane season so if something does threaten there are plans in place. Myself along with quite a few other bloggers on WU are from cayman so Im sure you will be kept updated.

thankyou saltydog for the reply i will keep check on the blog for news going to speak to him in the morning should know more by then :)
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Quoting CaicosRetiredSailor:
Would that be the center/eye west of St Lucia now in the Caribbean ?
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21L/H/T/C1
MARK
13.26n/61.73w


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Quoting Saltydogbwi1:


Evening Marco...I also live in Savannah Grand Cayman and we are watching this one closely no preparations being made yet but we tend to err on the side of caution since hurricane Ivan in 2004. Since Ivan everyone here is better prepared from the beginning of hurricane season so if something does threaten there are plans in place. Myself along with quite a few other bloggers on WU are from cayman so Im sure you will be kept updated.
I am here too but in East End and have decided if the turn has not begun by Tuesday to start shuttering up etc. Got a feeling he might come further west than currently projected due to the high uncertainty of the forecast path per NHC.
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Quoting Gorty:
Sorry to go off topic but is there a blog here specificaly for winter weather? That will be nice for when winter weather is forecasted.


Blizzard92 has a good one here.
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Quoting Gorty:
Sorry to go off topic but is there a blog here specificaly for winter weather? That will be nice for when winter weather is forecasted.
That is not off topic. When winter weather begins to set in the discussions here are about that. You can still come to the same place.
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Quoting KEEPEROFTHEGATE:


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

----- Current Analysis -----
Date : 30 OCT 2010 Time : 201500 UTC
Lat : 13:28:08 N Lon : 61:16:38 W


CI# /Pressure/ Vmax
3.1 / 998.8mb/ 47.0kt


Final T# Adj T# Raw T#
3.1 3.5 4.1

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -70.6C Cloud Region Temp : -69.6C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

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

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

****************************************************


Looks stronger than 3.5 to me. It appers to be a 4.2-4.3 to me, becoming a 4.5 at 8
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Quoting weatherwatcher12:
Where did everyone go?
I am here but since I have nothing to add just lurking. LOL
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Quoting MarcoIslandCat5:
Good evening all, Long time lurker here learnt soo much from some of u guys! just a quick question, My son is currently staying in savannah in the cayman islands. He is staying with relatives of his best friend, what are the chances of the caymans seeing hurricane winds?? should he be prepareing for a storm?? thanks
Florida pete,


Evening Marco...I also live in Savannah Grand Cayman and we are watching this one closely no preparations being made yet but we tend to err on the side of caution since hurricane Ivan in 2004. Since Ivan everyone here is better prepared from the beginning of hurricane season so if something does threaten there are plans in place. Myself along with quite a few other bloggers on WU are from cayman so Im sure you will be kept updated.
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It's really weird watching the clouds go in the opposite direction to usual...
Member Since: August 21, 2010 Posts: 0 Comments: 96
Quoting Inactivity:
Anyone have Davork readings?


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

----- Current Analysis -----
Date : 30 OCT 2010 Time : 201500 UTC
Lat : 13:28:08 N Lon : 61:16:38 W


CI# /Pressure/ Vmax
3.1 / 998.8mb/ 47.0kt


Final T# Adj T# Raw T#
3.1 3.5 4.1

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -70.6C Cloud Region Temp : -69.6C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

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

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

****************************************************
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510. Gorty
Quoting KEEPEROFTHEGATE:
Link


Heh, very nice, and its yours! haha. Thanks
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Where is recon?

18Z is 2pm, they should be there by now
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508. Gorty
Quoting Inactivity:
Anyone have Davork readings?


HA! Don't get them from me, I am not skilled in that technique yet!

Tomas does have a much better center, it is far better organized.
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Good evening all, Long time lurker here learnt soo much from some of u guys! just a quick question, My son is currently staying in savannah in the cayman islands. He is staying with relatives of his best friend, what are the chances of the caymans seeing hurricane winds?? should he be prepareing for a storm?? thanks
Florida pete,
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Quoting Gorty:
Sorry to go off topic but is there a blog here specificaly for winter weather? That will be nice for when winter weather is forecasted.
Link
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Anyone have Davork readings?
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Hiya...

I live in Caracas and we had rain some hours ago, we're waiting for heavy rains tonight, tomorrow and also on monday...

I have a weather blog on a site here (always with your help) and I can warn to all the people who see me here...

Flu, by the way...

Keep in touch bro...
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SLU, what festival is this weekend in St. Lucia? I saw the fishing tournament..
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502. Gorty
Sorry to go off topic but is there a blog here specificaly for winter weather? That will be nice for when winter weather is forecasted.
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Quoting gwadaman:
Afternoon all, im here sitting on our boat Grey Ghost in Rodney Bay (North side of Island) riding out the Hurricane. We came over from Barbados for the Fishing Tournament. Time is now 4:45pm and the wind is ripping in Rodney Bay we have no way of telling what the wind speed is bolwing thru here at.Our bigest problem is it will get dark in an hour. the Island is still out of power.


You're on a boat in a hurricane...? I hope that's a very large and secure boat.
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Quoting gwadaman:
Afternoon all, im here sitting on our boat Grey Ghost in Rodney Bay (North side of Island) riding out the Hurricane. We came over from Barbados for the Fishing Tournament. Time is now 4:45pm and the wind is ripping in Rodney Bay we have no way of telling what the wind speed is bolwing thru here at.Our bigest problem is it will get dark in an hour. the Island is still out of power.


No one is reacting, so I do it from Germany. Stay save during the night, keep us informed. All the best and thank you for posting in this aggravating situation!
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499. amd
Quoting atmoaggie:


thanks for the long radar loop. I was wondering where I could find something like that online. It really shows how there may have been dry air Saturday morning that temporarily weakened the eye, and how Tomas has really come together in the past few hours.
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This is a little random, but tell me if anyone else finds this a bit misleading...on the wind radius map, it shows the area of hurricane force winds being very small and directly in the center, but why would that be the case when the hurricane force winds are surrounding the center, in the eye wall? Should the graphic not reflect that as being the proper wind radius? Clearly, St. Lucia is still experiencing hurricane force winds, but if one were to judge the wind radius graphic, it would seem that the strong winds have passed. I don't get it.
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497. Gorty
Quoting weatherwatcher12:
Where did everyone go?


I know right?!? It just went dead.
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496. SLU
Quoting largeeyes:
No doubt the banana crop will be damaged, if not destroyed. Hasn't that industry dropped A LOT since the favorable status in the EU was dropped? Now, if the banana ketchup industry was disrupted, I'm not sure what the flea market would sell....


The banana industry has fallen and tourism has taken over but even that could take a beating too.
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Where did everyone go?
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Quoting jambev:
Slowly but surely the NHC track is swinging around to the model consensus after 5 days.

The track barely shifted as noted in the discussion, nowhere near model consensus.
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Quoting SLU:


Sure. What's for sure is that our vital Banana Industry could be completely destroyed. Those plants can't stand winds of more than 35 - 40mph.
No doubt the banana crop will be damaged, if not destroyed. Hasn't that industry dropped A LOT since the favorable status in the EU was dropped? Now, if the banana ketchup industry was disrupted, I'm not sure what the flea market would sell....
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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.

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