Alex continues to slowly organize

By: Dr. Jeff Masters , 7:17 PM GMT on June 28, 2010

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Tropical Storm Alex continues to slowly grow more organized as it steams away from Mexico's Yucatan Peninsula. Satellite loops show that Alex's heavy thunderstorms continue to increase in areal extent, and low level spirals bands are slowly building to the south and north. The clockwise flow around an upper-level high pressure system a few hundred miles west of Alex is bringing about 15 knots of wind shear to the storm, which is slowing intensification. Heavy thunderstorm activity is limited on the storm's northwest side, thanks to the shear and some dry continental air flowing off the coast of North America. Sea Surface Temperatures are very warm, 29°C. The latest Hurricane Hunter center fix, at 12:07 pm CDT, showed a central pressures of 990 mb, a 1 mb rise in six hours. Top winds were holding steady near 60 mph. Alex has stalled out the last few hours, as it began to "feel" the trough of low pressure to its north breaking down the high pressure ridge that has been pushing the storm to the west-northwest. This stall has allowed the storm to churn up cold water from the depths, which is probably interfering with development. Satellite loops show that Alex has a very large circulation covering about 2/3 of the Gulf of Mexico. We can expect that should Alex become a Category 2 or stronger hurricane, its storm surge will affect a much wider stretch of coast than Hurricane Dolly of 2008 did.


Figure 1. Afternoon satellite image of Alex.

Track forecast for Alex
The latest 12 UTC (7am CDT) runs of our most reliable computer models have come into much better agreement. A consensus forecast arrived at by averaging together most or all of the tracks of our top models--the GFS, ECMWF, GFDL, NOGAPS, HWRF, UKMET, and GFDN--is pretty much what NHC always uses as the basis of their forecast. This consensus forecast has narrowed in on the region just south of the Texas/Mexico border as being the most likely landfall location, with the usual cone of uncertainty surrounding it. The computer model that had been making the northernmost landfall predictions, the Canadian model, is now projecting a landfall 100 miles south of the Texas/Mexico border. There has been a general southward shift of the models in their latest runs, and the most northerly landfall location, near Port Mansfield, is now being predicted by the HWRF model. The earliest landfall time is Wednesday morning, and the latest is Thursday morning. Which model should you trust? Last year, the best performing models at the 3 day forecast period were the GFS, Canadian, ECMWF, and GFDL.

With steering currents relatively weak, the uncertainty in landfall location is high. The average error in an NHC 72-hour track forecast last year was 230 miles, which is about the distance from Brownsville to Port O'Connor. Consider also that the NHC cone of uncertainty is the region where 2/3 of the time (using the last 5 years of statistics) the center of a storm will go. Forecast errors tend to be equally large along track (speed errors) and cross-track (deviations from side-to-side), so that means that about 20% of the time a storm will not be in the cone of uncertainty. Given the slow motion of Alex and the recent uncertainty of the computer models, people living just beyond the edge of the cone of uncertainty should not be confident yet that Alex will miss them.

To get the probability of receiving tropical storm force winds or hurricane force winds for your location, I recommend the NHC wind probability forecasts. The 10am CDT (15 UTC) wind probability product predicted that Brownsville, Texas had the highest odds of getting a direct hit from Alex:

Brownsville, TX: 67% chance of tropical storm conditions (winds 39+ mph), 16% chance of hurricane force winds (74+ mph). This is the cumulative probability through Saturday morning. The wind probability forecasts also include separate probabilities for each 12-hour period between now and three days from now, and each 24 hours for the period 4 - 5 days from now.

La Pesco, MX: 49% tropical storm, 6% hurricane.

Tampico, MX: 31% tropical storm, 4% hurricane.

Corpus Christi, TX: 45% tropical storm, 6% hurricane.

Freeport, TX: 23% tropical storm, 2% hurricane.

Galveston, TX: 21% tropical storm, 1% hurricane.


Figure 2. Skill of computer model forecasts of Atlantic named storms during 2009. OFCL=Official NHC forecast; GFS=Global Forecast System model; GFDL=Geophysical Fluid Dynamic Laboratory model; HWRF=Hurricane Weather Research Forecasting model; NOGAPS=Navy Operational Global Prediction System model; UKMET+United Kingdom Met Office model; ECMWF=European Center for Medium Range Weather Forecasting model; CMC=Canadian GEM model; TVCN=one of the consensus models that lends together all (or most) of the above models; BAMM=Beta and Advection Model (Medium Layer.) Image credit: National Hurricane Center 2009 verification report.

Uncertainty in the NHC Cone of Uncertainty
A research project funded by NOAA known as the Joint Hurricane Testbed has produced a remarkable number of tools now in operational use at the National Hurricane Center to improve hurricane forecasts and warnings. One of these projects, called "Prediction of Consensus TC Track Forecast Error and Correctors to Improve Consensus TC Track Forecasts", was an effort by Dr. Jim Goerss at the Navy Research Lab to improve the accuracy of the NHC "cone of uncertainty" (AKA the "Cone of Death") showing where a storm is expected to track 2/3 of the time. The radius of the circles that make up the cone are based on error statistics of the official NHC forecast over the past five years. We can expect in certain situations, such as when the models are in substantial disagreement, a consensus forecast made using these models will have much greater than average errors. Since the NHC typically bases their forecast on a consensus forecast made using a combination of reliable hurricane forecasting models, it is instructive to view the "GPCE" (Goerss Prediction Consensus Error) circles to see if the uncertainty cone should be smaller or larger than usual. The consensus forecast I'll look at is called "TVCN", and is constructed by averaging the track forecasts made by most of (or all) of these models: GFS, ECMWF, NOGAPS, GFDL, HWRF, GFDN, and UKMET. In the case of this morning's 12 UTC (7am CDT) June 28 run of these models, here is what the radius of the "cone of uncertainty" should be, in nautical miles:

12 hours: 42 nm
24 hours: 73 nm
36 hours: 96 nm
48 hours: 112 nm
72 hours: 173 nm
96 hours: 327 nm
120 hours: 376 nm

And here is the radius of NHC's "cone of uncertainty" for their official forecast, based on the average errors for the past five years:

12 hours: 36 nm
24 hours: 62 nm
36 hours: 85 nm
48 hours: 108 nm
72 hours: 161 nm
96 hours: 220 nm
120 hours: 285 nm

So, the GPCE error estimates are showing that the latest forecasts for Alex out to 72 hours are 4% - 17% higher in uncertainty than average. The 4 - 5 day forecasts are 32% - 49% more uncertain than average--but of course, we expect Alex to be inland at those times.

Intensity forecast for Alex
Alex is currently over a region of ocean with relatively low total ocean heat content (about 10 - 30 kJ/cm^2). By Tuesday and Wednesday, the heat content will increase to 40 - 70 kJ/cm^2, which is high enough to allow Alex to rapidly intensify. Wind shear is currently a moderate 15 knots, and is projected by the SHIPS model to decrease to the low range, below 10 knots, on Tuesday and Wednesday. The combination of low wind shear and high ocean heat content should allow Alex to intensify into a hurricane. NHC is giving Alex a 78% chance of being a hurricane on Wednesday morning, and a 16% chance it will be a major hurricane at that time. Water vapor satellite images, though, show plenty of dry air over Texas and the adjoining waters, and this dry air may turn out to be a significant detriment to Alex. Another factor limiting Alex's intensification may be that the atmosphere is more stable than usual right now--temperatures at 200 mb are a rather warm -50°C, and are expected to warm an additional 1 - 2 degrees by Wednesday. Another factor limiting Alex's intensification may be its slow forward speed. Alex has already stalled out once, and may stall out later in its path, as well. A stalled-out storm tends to pull up cold water from the depths, limiting intensification. In short, Alex has the potential to intensify into a major hurricane, but there are enough roadblocks that I give a 20% chance of this happening.

Elsewhere in the tropics
None of the reliable computers models is calling for tropical storm formation over the the next seven days in the Atlantic.

Wind and ocean current forecast for the BP oil disaster
It currently appears that Alex will not directly affect the oil slick location, other than to bring 2 - 4 foot swells to the region on Wednesday. However, because Alex is such a deep low pressure region, strong southeast winds of 15 - 25 knots will blow over the oil slick region today through Wednesday, according to the latest marine forecast from NOAA. The resulting currents should act to push oil to the west and northwest onto portions of the Louisiana, Mississippi, and Alabama coasts, according to the latest trajectory forecasts from NOAA and the State of Louisiana. Oil will also move westward along the central Louisiana coast towards the Texas border.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Portlight continues its Haiti response
Hurricane season is here, and Haiti is not ready. Over 1.5 million Haitians are living outside in tents or under tarps, and are highly vulnerable to a hurricane. Portlight is working on constructing steel shelters out of shipping containers for homeless Haitians, as detailed in the Haitian Relief Recap blog post. Please visit the Portlight.org web site or the Portlight blog to learn more and to donate to Portlight's efforts in Haiti.


Figure 3. Still frame from the remarkable video taken inside the Haitian Presidential Palace during the 2010 earthquake.

To remind people of just how devastating the earthquake was, the Haitian government released a video earlier this month showing the inside of the Haitian Presidential Palace during the mighty Haitian earthquake.

Next post
Dr. Rob Carver is planning on making a post late tonight, and I'll have an update by 9:30am CDT on Tuesday.

Jeff Masters

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Good night. I wonder what Alex will look like in the morning. I strongly believe that Alex will get stronger than the current NHC forecast of 90 mph. I think that forecast is too low.
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I still say Northerly when you average it.



AOI
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2805. xcool
NOAA G-IV not all dat was put in models i just find out .
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so GlobalWarming will it be very soon like in 3-7 days or will it be later is is there anything out there now
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2803. jpsb
Quoting Skyepony:
Alex tore up Darby this afternoon.
A late lunch, lol. W
Quoting iluvjess:
Well CNN just cleared it all up for us. Alex will make landfall around 2:00 AM Thursday just South of Brownsville...
Greaqt now I can go to bed and sleep soundly.
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Quoting mtyweatherfan90:
Finally a NW movement of Alex.

Link


Id say NNW
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Quoting GlobalWarming:


Why is the Xtrap model taking it towards Houma, La? Gulp, :(.


XTRAP is not a model. It is just a demonstration of what would happen were the storm to continue on its present heading.
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Quoting GaltsGulchCO:
would upwelling and aerating crude oil in a hurricane vortex "lubricate" or otherwise have a material effect on the intensity? I did not see this in Dr. M's previous post on the subject, and while this will (hopefully) not be an Alex issue, it was a question which jumped to mind.

First thought is that there isn't enough crude on the surface to actually have any effect. It would have to be a dang strong effect for the volume available to do anything...
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Quoting AlexEmmett:

oh 60kt would be 69.047 strong ts very close now
Again those are flight level. What you have to look at is the flight level winds (68 knots) and translate it to surface winds (about 51 knots).
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting mtyweatherfan90:
Finally a NW movement of Alex.

Link


You need three points to make an average... so I would say 350.... Northerly.
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2796. Levi32
Quoting Daveg:


BAM suite shifted northward which is interesting.
Member Since: November 24, 2005 Posts: 635 Comments: 26685
2795. guygee
Quoting LightningCharmer:

It is not just you, I have to go clear out my cache, plus I get annoying white breaks in the loops sometimes with Flash. Got all the latest software. The switchover has its good and bad, and on the SSD site I still use Java when I have problems with Flash.
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Finally a NW movement of Alex.

Link
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Quoting MiamiHurricanes09:
Those are flight level winds and are not at the surface.

oh 60kt would be 69.047 strong ts very close now
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Quoting LightningCharmer:


Thanks. Looking at the current water vapor, it appears the ULL will be over the Bahamas today, Tuesday.
I see what u mean; the SW arc of it is already over the SE Bahamas. Still not quite sure what mechanism will cause it to just "go away" by Friday....
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Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting AlexEmmett:

68kts is 78.253 damn cat1


That is at flight level not surface.
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2789. will45
Quoting AlexEmmett:

68kts is 78.253 damn cat1


Thats flight level
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txsweetpea... Alex is all over the place. Your guess is as good as ours at this point. LOL
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Quoting Levi32:


Flight-level....translates to 51 knots at the surface.

oh well but its gettign closer
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2786. Levi32
Quoting Asta:
Yes- the Coriolis effect. Thanks.


Coriolis effect is what makes the storm spin, not what tells it where to go.
Member Since: November 24, 2005 Posts: 635 Comments: 26685
Quoting GaltsGulchCO:
would upwelling and aerating crude oil in a hurricane vortex "lubricate" or otherwise have a material effect on the intensity? I did not see this in Dr. M's previous post on the subject, and while this will (hopefully) not be an Alex issue, it was a question which jumped to mind.


The oil slick will not have an appreciable effect on intensity.
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Quoting AlexEmmett:

68kts is 78.253 damn cat1
Those are flight level winds and are not at the surface.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting AlexEmmett:

68kts is 78.253 damn cat1


Thats flight level. Converts down to about 55kts or so at the surface.
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2782. scott39
Quoting Levi32:


Recon can't lie....and it's hard to tell when you have a CDO unless you have an eye.
probably just looking at the storms moving that way
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2781. Levi32
Quoting AlexEmmett:

68kts is 78.253 damn cat1


Flight-level....translates to 51 knots at the surface.
Member Since: November 24, 2005 Posts: 635 Comments: 26685
2780. Daveg
Member Since: September 23, 2005 Posts: 0 Comments: 426
Night tc, I'm headed there before long myself! Especially since I have a Prob & Stat exam on Wed...Levi, you there...Wanna swing by and take that for me ;)
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Hello All!!!! Just got to get back to the blog. Is Alex still going to "the west"? Need Info, Thanks.
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2777. Levi32
000
URNT12 KNHC 290354
VORTEX DATA MESSAGE AL012010
A. 29/03:41:00Z
B. 21 deg 04 min N
091 deg 40 min W
C. 925 mb 555 m
D. 43 kt
E. 127 deg 11 nm
F. 206 deg 56 kt
G. 129 deg 15 nm
H. EXTRAP 985 mb
I. 22 C / 762 m
J. 23 C / 758 m
K. 21 C / NA
L. NA
M. NA
N. 1345 / 9
O. 0.02 / 1 nm
P. AF304 0701A ALEX OB 13
MAX FL WIND 68 KT NE QUAD 01:59:00Z
MAX OUTBOUND FL WIND 60 KT NW QUAD 03:47:40Z

SLP EXTRAP FROM 925 MB
Member Since: November 24, 2005 Posts: 635 Comments: 26685
Well CNN just cleared it all up for us. Alex will make landfall around 2:00 AM Thursday just South of Brownsville...
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LOL AlexEmmett... I hear ya. But I cleaned it up and did not spell it out ;o)
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Quoting KEEPEROFTHEGATE:
816

URNT12 KNHC 290354

VORTEX DATA MESSAGE AL012010

A. 29/03:41:00Z

B. 21 deg 04 min N

091 deg 40 min W

C. 925 mb 555 m

D. 43 kt

E. 127 deg 11 nm

F. 206 deg 56 kt

G. 129 deg 15 nm

H. EXTRAP 985 mb

I. 22 C / 762 m

J. 23 C / 758 m

K. 21 C / NA

L. NA

M. NA

N. 1345 / 9

O. 0.02 / 1 nm

P. AF304 0701A ALEX OB 13

MAX FL WIND 68 KT NE QUAD 01:59:00Z

MAX OUTBOUND FL WIND 60 KT NW QUAD 03:47:40Z

SLP EXTRAP FROM 925 MB

;

68kts is 78.253 damn cat1
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would upwelling and aerating crude oil in a hurricane vortex "lubricate" or otherwise have a material effect on the intensity? I did not see this in Dr. M's previous post on the subject, and while this will (hopefully) not be an Alex issue, it was a question which jumped to mind.
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Quoting atmoaggie:

Well, about the rainfall, sunlight,etc. Umm, nose joway.
Lacking sunlight for a few days and, ahh, let's go big, 45 inches of rain, is not going to cool 30 meters (90 feet+) of water in a measurable way if the water were uniformly warm for the whole column.

BUT, these waters are not warm all the way down. Our best examples of deep, warm waters get that way over years and years in the tropics. Shelf waters, even in the BOC had both a cold winter and guess where colder fresh water from the land flow goes. Under the warm surface waters.

I also used to question if the TCHP really did capture the depth of warm waters on the shelf. Eventually worked out that it really cannot be full column warm mixed as there are no currents to force stably stratified colder water 10 meters+ below to the surface and conduction isn't going to do it.

Some of this is a bit on the supposition side. If anyone knows better and has info to share, please do. (preferably with some links)


I guess this is something that hasn't really been researched much. I would be interested to see how much the water temps have changed after Alex has left the region and compare it to a system that stalled over a deep area of water for about the same period of time. I'm wondering because it doesn't seem to me that cold water upwelling is causing any issues for Alex, the water temps are lowering for sure but still seem plenty warm enough to allow Alex to create plenty of convection. But what if Alex was over a deep area of water and this same situation was happening? I bet it would be having a lot more issues creating convection.

The current issues I see with Alex is that wind shear injected dry air into Alex's core last night and is still fighting with it.
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Quoting HoustonTxGal:
It is like Alex is just sitting there trying to decide who he wants to go mess with. As my grandmother says... "he needs to S#*t or get off the pot!"

careful you dont wanna get banned
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2767. KEEPEROFTHEGATE (Mod)
816

URNT12 KNHC 290354

VORTEX DATA MESSAGE AL012010

A. 29/03:41:00Z

B. 21 deg 04 min N

091 deg 40 min W

C. 925 mb 555 m

D. 43 kt

E. 127 deg 11 nm

F. 206 deg 56 kt

G. 129 deg 15 nm

H. EXTRAP 985 mb

I. 22 C / 762 m

J. 23 C / 758 m

K. 21 C / NA

L. NA

M. NA

N. 1345 / 9

O. 0.02 / 1 nm

P. AF304 0701A ALEX OB 13

MAX FL WIND 68 KT NE QUAD 01:59:00Z

MAX OUTBOUND FL WIND 60 KT NW QUAD 03:47:40Z

SLP EXTRAP FROM 925 MB

;
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2766. Levi32
Quoting scott39:
Levi. does it look like on the Sat that Alex is starting to go more NNW?


Recon can't lie....and it's hard to tell when you have a CDO unless you have an eye.
Member Since: November 24, 2005 Posts: 635 Comments: 26685
2765. Daveg
Member Since: September 23, 2005 Posts: 0 Comments: 426
so guys when will we have 95L any guesses where will it be and coming from
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It is like Alex is just sitting there trying to decide who he wants to go mess with. As my grandmother says... "he needs to S#*t or get off the pot!"
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2762. tkeith
2559. nrtiwlnvragn 10:19 PM CDT on June 28, 2010

roger...
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2761. Asta
Yes- the Coriolis effect. Thanks.
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nite chicklit and storm and all others off to bed. i too can barely keep my eyes open.
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As I asked in post2597, could somebody PLEASE check this to see if I've entered the correct coordinates or have miscalculated the numbers, cuz
TropicalStormAlex heading toward DeepwaterHorizon spillfall within 4days.
(Straightline projection using its last 2 positions. Take with HUGE grain of salt)

Copy&paste TAM, MOB, PBI, SAL, 19.7N91.6W, 20.3N91.7W-28.7N88.4W, 20.5N91.8W-28.7N88.4W, 21.0N91.6W-28.7N88.4W, 20.5N91.8W-21.0N91.6W into the GreatCircleMapper.

The shortest red line shows the heading between the last two positions. Below the map shows:
TSAlex had a heading of 20.6degrees (~2degrees north of NorthNorthEast), while
traveling a distance of 37miles(~60kilometres) over 6hours at a speed of 6mph(~10kph);
TSAlex's distance from DeepwaterHorizon* decreased by 36miles from 603miles to 567miles;
the previous closure rate was ~2mph, and at the current closure rate of 6mph,
TSAlex remains ~95hours away from the DeepwaterHorizon.

At 120hours away, personnel evacuations & shutdown procedures for ship evacuations begin.
Even knowing that straightline projections are almost always wrong, especially over long distances, AdmiralAllen and BP have gotta be chewin' on nails with worry... rusty nails.
(See the bottom of blog1521post705 for more info, & blog1521post3353 before obvious corrections)

* Which I've been marking as 28.7N88.4W
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Quoting Grecojdw:


Yes for all of us in the Northern Gulf, Texas this is your storm for the taking.


I'll second that motion. :-)
Member Since: July 24, 2006 Posts: 1 Comments: 987
Quoting BahaHurican:
I was looking at that ULL on OPC's forecast page, and they are suggesting it will be over the NW Bahamas by Wednesday but disappated by Friday....


Thanks. Looking at the current water vapor, it appears the ULL will be over the Bahamas today, Tuesday.
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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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