Huge Western Caribbean low bringing heavy rains; Wisconsin levee failing

By: Dr. Jeff Masters , 12:26 PM GMT on September 27, 2010

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Today, for the first day since August 20, the National Hurricane Center will not be issuing any advisories for an Atlantic named storm. Thus ends a remarkably active 36-day period that saw the formation of ten named storms, six hurricanes, and five intense hurricanes--an entire hurricane season's worth of activity, compressed into just five weeks of the six-month season. This season is not done yet, as we still have three more weeks of peak hurricane season left to go, and the Western Caribbean is looking poised to generate a tropical storm sometime in the next ten days.


Figure 1. Morning satellite image of the Western Caribbean and Central America, showing the remains of Matthew over Mexico, and a large area of disturbed weather beginning to develop over the Western Caribbean.

A wet week ahead for the Western Caribbean, Florida, and the Western Bahamas
Pressures are falling over the Western Caribbean today as a large area of low pressure develops over the region. This low is bringing heavy rains across a huge area, from the Pacific shores of El Salvador, Guatemala, and Mexico, to eastern Cuba and Haiti. All of Central America, eastern Mexico, the western 2/3 of the Caribbean, plus the Bahamas and Florida can expect sporadic periods of very heavy tropical rains over the coming week, with peak amounts of 3 - 6 inches per day possible. In the Western Caribbean, a few hundred miles east of Mexico's Yucatan Peninsula, a region of concentrated thunderstorms has built this morning, and has the potential to develop into a tropical depression by Wednesday. A large trough of low pressure over the Eastern U.S. is producing steering currents that will pull this area of disturbed weather to the north-northeast across western Cuba on Tuesday and Wednesday. The disturbance should move over Florida on Wednesday and Thursday, and over North Carolina by Thursday and Friday. All of these regions can expect very heavy rains from the disturbance, and NHC is giving a 30% chance that the disturbance will develop into a tropical depression by Wednesday. The Hurricane Hunters are on call to investigate the disturbance this afternoon, if necessary.

Once the disturbance moves out of the Caribbean, the GFS and NOGAPS models predict that the Western Caribbean will "reload" and produce another tropical disturbance capable of developing into a tropical depression late this week or early next week. The steering currents are not expected to change over the coming ten days, and Florida and western Cuba can expect to see this second disturbance potentially bring a second round of heavy rain late this week and early next week.

Levee failing in Wisconsin due to rains from Hurricane Karl's moisture
In Portage, Wisconsin, about 25 miles north of Madison, a sub-standard 120-year-old levee is failing, thanks to flood waters 3.5 feet above flood stage on the Wisconsin River. The river was swollen last week by heavy rains of up to seven inches that fell in its watershed to the northwest. The rains were generated by a plume of very moist air associated with what was Hurricane Karl. This moisture was lifted over a warm front draped over Minnesota and Wisconsin on Wednesday and Thursday. These types of rain events are called Predecessor Rain Events (PREs), because they typically precede the actual arrival of the rain shield of a tropical storm.


Figure 2. Rainfall over Minnesota and Wisconsin for the seven-day period ending 8pm EDT Sunday 9/26/10. Heavy rains to the northwest of Portage, Wisconsin led to flooding along the Wisconsin River in Portage. Image credit: NOAA.

Canadian Military responds for Hurricane Igor relief
At least twenty communities in Newfoundland, Canada are still cut off from civilization after Tuesday's rampage by Hurricane Igor. The Canadian military has sent three warships and a number of helicopters into the disaster zone to deliver food, fuel, and medical supplies to those communities still cut off. Igor killed one person and caused over $100 million in damage to the island.


Figure 3. Miniature golf anyone? A house in St. John's Newfoundland now has a very three-dimensional front yard, thanks to Hurricane Igor's winds and rain. Image credit: Zach Goudie.

I'll have an update Tuesday morning.

Jeff Masters

Wisconsin River Flooding in Wisconsin Rapids September 2010 (LadyWriter)
Jackson Street Bridge late Saturday afternoon at cresting.
Wisconsin River Flooding in Wisconsin Rapids September 2010
Wisconsin River Flooding in Wisconsin Rapids September 2010 (LadyWriter)
Taken from First Avenue while looking eastward toward Grand Avenue Bridge/Elks Club when the flooding was at its worst
Wisconsin River Flooding in Wisconsin Rapids September 2010

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Quoting barotropic:
Just checked and pressure falls have seemed to level off in the area (caymans and bouys) at 1001 - 1002 mb.
1.77" rain since midnight.
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Both the GFDL and HWRF 06z runs are showing Cat 1 in the Keys/S. Florida area... that's not good.
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Just checked and pressure falls have seemed to level off in the area (caymans and bouys) at 1001 - 1002 mb.
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2611. 7544
nicloe will be the practice storm for what follows

Link
Member Since: May 6, 2007 Posts: 0 Comments: 6874
is there any chance of the front retreating a bit? It looks stalled to me on radar.
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So satellite show 2 "blobs" of convection. Am i correct that the "center" is in the middle of them? Or is it the "blob" on the right?
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Quoting Jeff9641:
Models have shifted left with 96L with the HWRF showing a 100mph storm over Cape Canaveral. The GFS, NAM, CMC, and Euro show this system now exiting near Cape Canaveral. Track toward SW FL then NE to Cape Canaveral. Naples NNE will be the track.


I don't see 100mph, but I do see a Cat 1 from the HWRF... that is definitely increased from before.
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http://www.ndbc.noaa.gov/station_page.php?station=42056

Wind switched to west and NW on the 056 buoy.

That would put the center to the NE of that Buoy.
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2605. Grothar
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Quoting cat5hurricane:
Shear Forecast



Doesn't look too bad. Might see a stronger system
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Good Morning All!

Looks like there is already a fair amount of northerly shear over 96L (on the west side of the trough axis).
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2600. IKE
What a trough in the east...my low was 58.8.....

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Quoting BobinTampa:
I don't think we've gotten a drop of rain in Tampa. All the computer models had us getting 5+



Bob,
Had a nice time in Tampa. What a great city. Will be back up for the Pitt vs. USF game.
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Quoting ILwthrfan:


Next year has the potential to be even worse if we don't get that heat out of the Carribean.


Polar ice? ;)
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Quoting hunkerdown:
except the convection mass futuremet is referring to is not further south, more to the E/ENE


I agree and as a matter of fact I think this could result in a system that tracks just a bit more to the east which would keep it offshore florida. As the circulation moves north the west side in particular will be hit hard by southerly shear. I expect a pretty sloppy system with florida being on a weaker sheared side
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I don't think we've gotten a drop of rain in Tampa. All the computer models had us getting 5+

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Quoting cat5hurricane:

At least compared to Matthew, this is a VERY tight consensus!
I know.
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Quoting ILwthrfan:


Next year has the potential to be even worse if we don't get that heat out of the Carribean.


Love hearing about the 06z GFS 8160h =)
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Quoting MahFL:


The HH will be over the disturbance at 10:30 am EDT.
Sounds good. I think sooner rather than later will be better for us. Our government tends to wait until something is knocking on the front door to put up warnings. I work at the post office on the southeast coast right across the street from the sea. Means taking all the mail out of the boxes, covering electronics with plastic and basically securing the post office.
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2588. MahFL
Quoting stormwatcherCI:
AN AIR FORCE RESERVE UNIT HURRICANE HUNTER AIRCRAFT IS
SCHEDULED TO INVESTIGATE THIS SYSTEM LATER TODAY.

I wonder what time it will go out there. At least then we will know for sure what is going on.


The HH will be over the disturbance at 10:30 am EDT.
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Good consensus on where it is headed. Homestead-south and northern Bahamas need to keep a heads up.Link
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2586. pottery
Good Morning all.
Lovely morning here, but it looks to be a hot day.
96L is Threatening to get itself into gear today. Heavy rains in Cayman, which must also be a big threat to Jamaica.
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Quoting Neapolitan:
Assuming Nicole will be born today--and I don't think that's a wild assumption at this point--that would be 12 named storms during August and September. That hasn't happened during the current "active" period (1995 through now); the average over that span has been 8.1, and the maximum--11--has happened three times (2000, 2002, and 2004). (FWIW, 2005 had just ten in that two-month span, as did the hyperactive 1933 season.) Anyway, because I'm a weather nerd interested in such things, I'm looking to see how often twelve or more Aug/Sep storms have happened in the past. I'm sure it has, but I would imagine it's a fairly rare thing...


Next year has the potential to be even worse if we don't get that heat out of the Carribean.
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Naples here too....

Just spoke to Johnny Roberts On Great Guana Cay, Abaco. They are prepared. Looks like NW Bahamas will receive the brunt of the storm compared to South Fl.
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Quoting surfmom:
just an old nursey rhyme - means rains are coming
- Info-mercial time/Factoid for the day
The complete saying states: RED SKY IN MORNING, SAILORS WARNING; RED SKY AT NIGHT, SAILORS DELIGHT. This saying only applies to mid-latitude locations (winds are easterly in the tropics / in the high latitudes the sun rises and sets at a large deviation from the east-west trajectory). Storm systems in the middle latitudes generally move west to east. A red sky in the morning implies the rising sun in the east is shining on clouds to the west and conditions are clear to the east. Clouds moving from the west (especially upper level cirrus) indicate an approaching storm system. A red sky at night implies the sun (setting in the west) is shining on clouds to the east and conditions are clear to the west (because the sun can be seen setting). If you can see the sunset, the sky will be redder. Clouds to the east indicate an exiting storm system in the middle latitudes. Upper level clouds (especially cirrus) are noted for giving the sky a reddish hue during dawn or dusk. As a mid-latitude cyclone approaches, it is the upper level cirrus that are seen first, followed by lower clouds. The approach of upper level cirrus from the west often indicates an approaching storm system. The sky will not be as red at night if a storm system is approaching because the sun is setting behind the clouds approaching from the west. A red sky at night implies "the storm system moving through has ended!"; The clouds have broken and the sun is shining on and reddening the exiting clouds. The sun will continue to shine on clouds for a period of time after the sun has dipped below the horizon (especially cirrus). Keep in mind this saying was developed before satellite, radar and modern meteorological knowledge. Much of the knowledge of an approaching storm system back then was cloud and wind patterns. Of course, this saying (weather folklore) has some profound problems such as:

(1) The sky can be "reddish" near the sun at dawn and dusk (with or without clouds)
(2) storm systems do not always move straight west to east
(3) cirrus can occur without a storm system approaching or leaving. Clouds can cover one side of the sky or the other without being directly associated with a storm system
(4) the meteorological sailor may delight at an approaching storm system even while taking precautions at the same time
(5) rarely do the clouds from an approaching or exiting storm system only cover 1/2 of the eastern or western sky. The saying represents an ideal case.

SUMMARY: If you can see the sunrise but the west part of the sky is dark: look out for approaching bad weather. If you can see the sunset: the weather conditions will be nice.
the boat already left the dock :)
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2580. WxLogic
Based on Radar trends and Water Vapor imagery... the Front has lost momentum and stalled a couple counties to the N of my location (namely from Hernando County to Flagler County). PCPN from the SE is evident in radar indicating a deep SE flow is starting to come into CFL and should prevent further S propagation of the front. This should allow a further N displacement of the disturbance as it starts being drawn to the N then NE.
Member Since: August 14, 2008 Posts: 4 Comments: 5038
2579. surfmom
Quoting cat5hurricane:
Thank for that. I had completely forgotten that as well. LOL
It's good for us simple folks that still can't grasp the maps
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Why is that if the High is sitting in the Atlantic?
Quoting BenBIogger:


Would likely miss FL east coast.
Member Since: August 28, 2008 Posts: 0 Comments: 57
2577. surfmom
Quoting SpicyAngel1072:


Red Sky - Sailor's Warning? please explain.. thanks =)
just an old nursey rhyme - means rains are coming
- Info-mercial time/Factoid for the day
The complete saying states: RED SKY IN MORNING, SAILORS WARNING; RED SKY AT NIGHT, SAILORS DELIGHT. This saying only applies to mid-latitude locations (winds are easterly in the tropics / in the high latitudes the sun rises and sets at a large deviation from the east-west trajectory). Storm systems in the middle latitudes generally move west to east. A red sky in the morning implies the rising sun in the east is shining on clouds to the west and conditions are clear to the east. Clouds moving from the west (especially upper level cirrus) indicate an approaching storm system. A red sky at night implies the sun (setting in the west) is shining on clouds to the east and conditions are clear to the west (because the sun can be seen setting). If you can see the sunset, the sky will be redder. Clouds to the east indicate an exiting storm system in the middle latitudes. Upper level clouds (especially cirrus) are noted for giving the sky a reddish hue during dawn or dusk. As a mid-latitude cyclone approaches, it is the upper level cirrus that are seen first, followed by lower clouds. The approach of upper level cirrus from the west often indicates an approaching storm system. The sky will not be as red at night if a storm system is approaching because the sun is setting behind the clouds approaching from the west. A red sky at night implies "the storm system moving through has ended!"; The clouds have broken and the sun is shining on and reddening the exiting clouds. The sun will continue to shine on clouds for a period of time after the sun has dipped below the horizon (especially cirrus). Keep in mind this saying was developed before satellite, radar and modern meteorological knowledge. Much of the knowledge of an approaching storm system back then was cloud and wind patterns. Of course, this saying (weather folklore) has some profound problems such as:

(1) The sky can be "reddish" near the sun at dawn and dusk (with or without clouds)
(2) storm systems do not always move straight west to east
(3) cirrus can occur without a storm system approaching or leaving. Clouds can cover one side of the sky or the other without being directly associated with a storm system
(4) the meteorological sailor may delight at an approaching storm system even while taking precautions at the same time
(5) rarely do the clouds from an approaching or exiting storm system only cover 1/2 of the eastern or western sky. The saying represents an ideal case.

SUMMARY: If you can see the sunrise but the west part of the sky is dark: look out for approaching bad weather. If you can see the sunset: the weather conditions will be nice.
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What I don't get is that if this front is now south of us, why is it still raining with 98% Humidity?

Hudson, FL (34667)
76.1 °F
Mostly Cloudy
Humidity: 98%
Dew Point: 76 °F
Wind: 0.0 mphfrom the North

Wind Gust: 0.0 mph
Pressure: 29.69 in(Rising)
Heat Index: 75 °F
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2575. IKE
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2574. tkeith
Quoting Thundercloud01221991:
Subtropical... in that region of the world???
Could be subtropical if attatched to the front...I think
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It's a nice, crisp 67 degrees here in Galveston. The first cool front of the season always puts me in the mood for a pumpkin spice latte from Starbucks...liquid crack!
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Subtropical... in that region of the world???
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2570. 7544
looks like watches for so fla may go up latter on today after reading that 2 and might already be a td by then
Member Since: May 6, 2007 Posts: 0 Comments: 6874
Quoting cat5hurricane:

I agree. In this particular case if the center is indeed concentrated anywhere further south, it would have a much better chance at becoming a more potent system since it would have more time under relatively low shear & high TCHP's.
except the convection mass futuremet is referring to is not further south, more to the E/ENE
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2568. WxLogic
Quoting IKE:
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT TUE SEP 28 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A BROAD AREA OF LOW PRESSURE OVER THE NORTHWESTERN CARIBBEAN SEA
CONTINUES TO GENERATE WIDESPREAD THUNDERSTORMS AND STRONG GUSTY
WINDS TO NEAR TROPICAL STORM FORCE. ALTHOUGH THE LOWEST SURFACE
PRESSURES ARE LOCATED BETWEEN THE ISLE OF YOUTH CUBA AND GRAND
CAYMAN...THE STRONGEST WINDS ARE OCCURRING A COUPLE HUNDRED MILES
TO THE EAST AND SOUTH OF THIS LOCATION. THIS SYSTEM HAS THE
POTENTIAL TO BECOME A TROPICAL OR SUBTROPICAL CYCLONE BEFORE
MERGING WITH A FRONTAL SYSTEM NEAR THE FLORIDA PENINSULA BY LATE
TOMORROW. AN AIR FORCE RESERVE UNIT HURRICANE HUNTER AIRCRAFT IS
SCHEDULED TO INVESTIGATE THIS SYSTEM LATER TODAY. THERE IS A HIGH
CHANCE...80 PERCENT... OF THIS SYSTEM BECOMING A TROPICAL OR
SUBTROPICAL CYCLONE DURING THE NEXT 48 HOURS.

HEAVY RAINS AND STRONG GUSTY WINDS TO TROPICAL STORM FORCE ARE
EXPECTED TO AFFECT THE CAYMAN ISLANDS...JAMAICA...AND CUBA TODAY.
THESE WEATHER CONDITIONS ARE LIKELY TO SPREAD OVER THE FLORIDA
KEYS...SOUTHERN FLORIDA...AND THE NORTHWESTERN BAHAMAS LATER TODAY
AND WEDNESDAY. INTERESTS IN CUBA...THE CAYMAN ISLANDS...THE
FLORIDA KEYS...AND THE CENTRAL AND SOUTHERN FLORIDA PENINSULA
SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. FOR ADDITIONAL
INFORMATION...CONSULT STATEMENTS FROM YOUR NATIONAL WEATHER SERVICE
FORECAST OFFICE OR NATIONAL METEOROLOGICAL SERVICE.

AN AREA OF LOW PRESSURE...THE REMNANT OF TROPICAL DEPRESSION
JULIA...LOCATED ABOUT 150 MILES SOUTH-SOUTHEAST OF BERMUDA IS MOVING
WEST-NORTHWESTWARD NEAR 15 MPH. CONDITIONS ARE NOT CONDUCIVE FOR
SIGNIFICANT DEVELOPMENT AND THERE IS A LOW CHANCE...10 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE AGAIN DURING THE NEXT 48
HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH



At least we're getting a HH out today.
Member Since: August 14, 2008 Posts: 4 Comments: 5038
AN AIR FORCE RESERVE UNIT HURRICANE HUNTER AIRCRAFT IS
SCHEDULED TO INVESTIGATE THIS SYSTEM LATER TODAY.

I wonder what time it will go out there. At least then we will know for sure what is going on.
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Quoting stormwatcherCI:
Thanks for the thoughts. It's just that I know the possibility of it developing quickly in the western Caribbean so I am watching it close.


As are we all.
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well this sounds bad for us

000
ABNT20 KNHC 280909
TWOAT
SPECIAL TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
510 AM EDT TUE SEP 28 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SATELLITE AND SURFACE OBSERVATIONS INDICATE THE LARGE LOW PRESSURE
SYSTEM LOCATED OVER THE NORTHWESTERN CARIBBEAN SEA IS CONTINUING TO
STRENGTHEN AND THUNDERSTORM ACTIVITY IS BECOMING BETTER ORGANIZED.
SURFACE PRESSURES ARE FALLING AND SUSTAINED WINDS HAVE NOW
INCREASED TO NEAR TROPICAL-STORM-FORCE. ENVIRONMENTAL CONDITIONS
ARE BECOMING MORE FAVORABLE FOR DEVELOPMENT...AND ONLY A LITTLE MORE
ORGANIZATION OF THE ASSOCIATED THUNDERSTORM ACTIVITY IS NEEDED FOR
THIS SYSTEM TO BECOME A TROPICAL DEPRESSION OR A TROPICAL STORM
AT ANY TIME>. THERE IS A HIGH CHANCE...80 PERCENT... OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. INTERESTS IN
CUBA...THE CAYMAN ISLANDS>...THE FLORIDA KEYS...AND THE CENTRAL AND
SOUTHERN FLORIDA PENINSULA SHOULD MONITOR THE PROGRESS OF THIS
SYSTEM. FOR ADDITIONAL INFORMATION... CONSULT STATEMENTS FROM YOUR
NATIONAL WEATHER SERVICE FORECAST OFFICE OR NATIONAL METEOROLOGICAL
SERVICE.


AN AREA OF LOW PRESSURE...THE REMNANT OF TROPICAL DEPRESSION
JULIA...LOCATED ABOUT 175 MILES SOUTH-SOUTHEAST OF BERMUDA IS MOVING
WEST-NORTHWESTWARD NEAR 15 MPH. CONDITIONS ARE NOT CONDUCIVE FOR
SIGNIFICANT DEVELOPMENT AND THERE IS A LOW CHANCE...10 PERCENT...
OF THIS SYSTEM BECOMING A TROPICAL CYCLONE AGAIN DURING THE NEXT
48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

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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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