Category 3 Hurricane Earl pounding northern Lesser Antilles and Puerto Rico

By: Dr. Jeff Masters , 2:40 PM GMT on August 30, 2010

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An intensifying Hurricane Earl is pounding Puerto Rico and northern Lesser Antilles Islands with heavy rain and high winds this morning. The eye of Earl passed just north of Anguilla at 9am EDT, and Juliana airport on neighboring St. Martin Island recorded sustained winds of 47 mph, gusting to 68 mph at 8am EDT before going silent. An Air Force Hurricane Hunter aircraft currently in Earl just found a central pressure of 960 mb at 9:42 am EDT. This is a significant drop of 25 mb in 25 hours. Top flight level winds at 10,000 feet seen by the Air Force aircraft were 128 mph. Using the usual rule of thumb that the surface winds are 90% of the 10,000 foot flight level winds gives one surface winds of 115 mph, which is right at the border of Cat 2/ Cat 3 strength. Top winds seen at the surface by the Air Force's SFMR instrument were lower, 104 mph. Recent satellite imagery shows that Earl is not perfectly symmetrical--there is still fewer heavy thunderstorms on the hurricane's north side, suggesting that upper-level northerly winds are bringing 5 - 10 knots of wind shear to the storm.


Figure 1. Radar image of Earl taken at 7am EDT 8/30/10 from the St. Maarten radar. Image credit: Meteorological Service of the Netherlands Antilles and Aruba.

Outlook for the Caribbean islands today
Latest radar animations out of Puerto Rico and St. Marten show that the eye of Earl is on track to pass just to the northeast of the islands of Anguilla, St. Maarten, and The Settlement in the British Virgin Islands today. The periphery of Earl's southern eyewall will probably bring Category 1 hurricane conditions to some of these islands today. NHC is giving its highest odds for hurricane-force winds to Saint Maarten--a 99% chance. These odds are 4% for St. Thomas in the Virgin Islands, and 2% for San Juan, Puerto Rico. The main threat to Puerto Rico will be heavy rains--up to eight inches in isolated areas. Earl's rains, in addition to causing flooding and dangerous landslides, will also help alleviate drought conditions that have affected many of the islands this year.

Intensity forecast for Earl
Wind shear as diagnosed by the latest SHIPS model forecast is nearly non-existent over Earl--just 3 knots--put is probably higher than that, based on the fact that the northern portion of Earl cloud pattern is ragged. Further evidence of this is the fact that Earl's eyewall had a gap in its west side, according to the latest report from the Hurricane Hunters. Ocean temperatures are a near-record 30°C, and very warm waters extend to great depth, resulting in a total ocean heat content highly favorable for rapid intensification. These nearly ideal conditions for intensification should bring Earl to Category 4 strength by Tuesday morning, and Category 5 is not out of the question. Earl should be able to maintain major hurricane status through Thursday, when it will make its closest approach to North Carolina. Sea surface temperatures are very warm, 29°C, along the U.S. East Coast, and wind shear is expected to remain low through Thursday. By Friday, when Earl will be making its closest approach to New England, wind shear will rise to a high 20 - 30 knots and ocean temperatures will plunge to 20°C, resulting in considerable weakening. Earl will still probably be a Category 2 hurricane on Friday, when it could potentially make landfall in Massachusetts or Nova Scotia, Canada.


Figure 2. Swath of surface winds from Earl predicted by the 2am EDT Monday August 30, 2010 run of NOAA's GFDL model. Hurricane force winds (yellow colors, 64 kt and above) are predicted to stay off the coast and tropical storm force winds (light green colors, 34 knots and above) are predicted to stay off the U.S. coast, but affect the coast of Canada. Image credit: Morris Bender, NOAA/GFDL.

Track forecast for Earl
Once Earl passes the Lesser Antilles, steering currents favor a northwesterly course towards North Carolina. History suggests that a storm in Earl's current location has a 25% chance of making landfall on the U.S. East Coast, and Earl's chances of making a U.S. landfall are probably close to that. None of the computer models show Earl hitting the U.S., but the storm will likely come uncomfortably close to North Carolina's Outer Banks and to Massachusetts. The latest set of model runs (2am EDT, or 6Z) project Earl will miss North Carolina by 200 - 300 miles on Thursday, and Massachusetts by a similar distance on Friday. Keep in mind that the average error in a 4 - 5 day NHC forecast is 200 - 300 miles, so the East Coast cannot breathe easily yet. The Outer Banks of North Carolina and Cape Cod, Massachusetts are both at the edge of the cone of uncertainty. NHC is giving Cape Hatteras a 9% chance of receiving hurricane force winds. These odds are 14% for Nantucket, 4% for Boston, and 2% for New York City. The main determinant of whether Earl hits the U.S. or not is a strong trough of low pressure predicted to move off the U.S. East Coast Friday. This trough, if it develops as predicted, should be strong enough to recurve Earl out to sea late in the week, with the storm just missing landfall in the U.S., but possibly making landfall in Nova Scotia, Canada.

Regardless of Earl's exact track, the U.S. East Coast can expect a long period of high waves beginning on Thursday. Significant beach erosion and dangerous rip current will be the rule, due to waves that will reach 10 - 15 feet in offshore waters (Figure 3.)


Figure 3. Wave forecast for 8am Friday, September 3, 2010, as produced by the 8pm EDT August 29 run of NOAA's Wavewatch III model. The model is predicting waves of 4 - 5 meters (13 - 16 feet) in the offshore waters from North Carolina to New Jersey.

Hurricane History for the northern Lesser Antilles
The last Cape Verdes-type hurricane to affect the Barbuda and the surrounding northern Lesser Antilles Islands was Hurricane Debby of 2000, which passed over the islands on August 28 as a Category 1 hurricane. Damage was less than $1 million, and no fatalities were reported. The last hurricane of any kind to pass through the northern Lesser Antilles Islands was Category 4 Hurricane Omar, on October 16, 2008. Omar took an unusual track, moving towards the northeast, and the storm's eyewall missed all of the islands. Omar did $80 million in damage to the Caribbean, mainly on the islands of Antigua, Barbuda, Dominica, the SSS Islands (Saba, St. Eustatius, and St. Maarten), and the U.S. Virgin Islands. No direct deaths were attributed to Omar, and the name Omar was not retired from the 6-year rotating list of hurricane names.

Links to track Earl
Wundermap of the northern Lesser Antilles Islands
Long range radar out of San Juan, Puerto Rico
Visible rapid scan satellite loop

97L
The tropical wave (Invest 97L) now 1000 miles east of the Lesser Antilles Islands has a well-defined surface circulation and enough heavy thunderstorms to be classified as a tropical depression, if it can maintain that state for another six or so hours. Satellite loops show the surface circulation clearly, but also that heavy thunderstorm activity has been slow to build. The storm is experiencing low wind shear of less than 5 knots, and is over warm 29°C waters. The main impediment to development continues to be dry air associated with the Saharan Air Layer (SAL) surrounding the storm. The latest SHIPS model forecast calls for shear to stay in the low range, 5 - 10 knots, through Tuesday, and this should allow 97L to organize into a tropical depression today or Tuesday. NHC is giving 97L a 90% chance of developing into a tropical depression by Wednesday.

97L is moving quickly to the west, at about 20 mph. This means it is catching up to Earl, which has slowed down to 14 mph. By Tuesday night, Earl is expected to be a large and powerful major hurricane with a well-developed upper-level outflow channel heading clockwise out from Earl's center at high altitudes. These strong upper-level winds will bring high levels of wind shear, 20 - 30 knots, to 97L, and probably arrest the storm's development. The most likely scenario depicted in the computer models is for 97L to be drawn into the low pressure wake of Earl and pass to the northeast of the Lesser Antilles. Earl would then eventually destroy 97L through high wind shear, and by robbing the storm of its moisture. An alternative scenario is that 97L will stay far enough away from Earl that it will be able to pass through the northern Lesser Antilles islands as a tropical storm on Wednesday and Thursday, then bend northwestwards to potentially threaten the Bahamas and U.S. East Coast. There is a very high degree of uncertainty on what may happen to 97L. History suggests that a storm in 97L's current location has a 25% chance of making landfall on the U.S. East Coast.


Figure 4. Morning satellite image of 97L.

Danielle
Hurricane Danielle is on its way to oblivion over the cold North Atlantic waters, and is only of concern to shipping interests.

Elsewhere in the Tropics
Over in the Western Pacific, tropical cyclone activity is ramping up, with two named storms expected to affect land this week. As is typical in a La Niña year, these storms have developed close to mainland Asia, and don't have a lot of time over water to intensify into strong typhoons. The storm of most concern is Typhoon Kompasu, which is expected to hit Okinawa today and recurve northward into Korea on Thursday. It now appears the Kompasu will not have major impacts on China's largest city, Shanghai. In the South China Sea, the fearsome sounding Tropical Storm Lionrock is forecast to hit the Chinese coast near Hong Kong on Tuesday, but is not predicted to develop into a typhoon.

The GFS model is predicting formation of a tropical depression off the coast of Africa about seven days from now.

Jeff Masters

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1481. SeaMule
it looks like Earl has stopped its fast motion wwnw at 15 mph, because it is on the west edge of the ridge. Now, one would think that it's time for Earl to start a more northerly track. However, the currents may not influence him much. the high is building in..Earl has created his own anti-cyclone above...and for this reason a continued motion...as is....ala wwnw or perhaps wnw...will probably continue...a tad slower, and for the next 24 hours. the door may shut for a turn north...and the east coast, and Florida...will soon be puckerin up!


imho
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1480. JLPR2
Impressive:
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Quoting Hurricanes101:


way to count your chickens WAY before they are hatched

97L still has a great chance of being Fiona


Perhaps. But 97L doesnt maintain convection in the afternoons. And last night it barely took advantage of Diurnal Max.

What are the chances of cat 4 Earl disrupting her environment, sending her 15 plus sheer? High. I'm not gripped to my chair wondering about 97L like i was last night. Pfft.
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1478. hydrus
Quoting Neapolitan:
So 97L has a closed circulation, great satellite presentation, persistent (though still light) convection at the center, a fairly low pressure of 1007, and winds of 35 knots...yet the NHC hasn't declared it a TD. Just wonderin'...
Well there givin her a 90% chance. So it must be dern near t.d.
Member Since: September 27, 2007 Posts: 1 Comments: 22643
Quoting Flyairbird:
to where? Oklahoma?
Mexico
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Quoting rwdobson:


The temperature in Toronto is pretty much 100% irrelevant. The trough is 1000 miles (maybe more) west of there.
I think we were both looking at our own forecasts, as most of the trough have to pass thru down here anyway in OHIO
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1474. 900MB
Storm- A couple questions for someone with interests in NYC and Montauk:
1- Once Early makes it past OBX, any guess on the forward speed passing Long Island. Remembering that when the "Long Island Express" happened, forward speed was a big contributing factor.
2- What do you make of that trough that we are waiting for? I think it is stationary right now, and not sure how strong it is?? A pretty strong high is sitting on top of us now and it is not forecast to move anytime soon. Could the trough nudge that high offshore and cause trouble for Long Island?
Okay, that was more than 2 questions. Much appreciated as always Storm!
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Everyone should take it easy and give a little more credit to the computer models that have been consistent on turning Earl before reaching the E coast.

Earl is going to turn into the trof very soon and will NOT make it anywhere near Florida.

When the model spread looks like a smashed spider and there are multiple scenarios being put forward, then we can watch each 1/18 mile of a wobble and talk of biting nails. But for this situation, let's sit back and watch a beautiful hurricane develop.
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Say Hello to Shrek's lovely wife
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1470. GetReal
Member Since: July 4, 2005 Posts: 204 Comments: 8898
1469. hydrus
Quoting will40:


its gonna have to stay stronggggggggggggggggggg to beat Hazel
Hazel was incredible...Pop told me his experience with Hazel...I asked, what was it like? He said BAD.
Member Since: September 27, 2007 Posts: 1 Comments: 22643
Quoting FloridaHeat:


is the brownish/organge color on that map the trough that will turn him


From the loop here it seems the brownish/orange is dry air representing the high dropping down and the trough that moved Danielle out that it appears Earl has missed. You can really see the clock-wise flow of the high on here above Earl. As for a trough to turn him north, there may be a small trough? over Alabama? And you can see a larger one clearly farther west. Hopefully it beats Earl to the coast. Not sure if that's what supposed to turn him though. Just thinking out loud. :)
Link
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1466. HadesGodWyvern (Mod)
National Hurricane Center
Tropical Cyclone Outlook
18:00 PM UTC August 30 2010
=======================================

Showers and thunderstorm associated with a broad area of low pressure area located several hundred miles south of Manzanillo, Mexico has not changed substantially in organization today. However, conditions appear conducive for some slow development of this system during the next couple of days as it moves west northwestward at 10 MPH.

Tropical Cyclone Formation Potential
======================================
There is a MODERATE chance of this disturbance to form into a significant tropical cyclone within the next 48 hours
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Quoting Flyairbird:
Based on your reports up there and mine here, I honestly don't think this trof is going to be all of that.


The temperature in Toronto is pretty much 100% irrelevant. The trough is 1000 miles (maybe more) west of there.
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Quoting sarepa:
Did Earl just did a little jog to the west?


Smell of Rum is giving him 2nd tough.
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So 97L has a closed circulation, great satellite presentation, persistent (though still light) convection at the center, a fairly low pressure of 1007, and winds of 35 knots...yet the NHC hasn't declared it a TD. Just wonderin'...
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Quoting LongIslandXpress38:


We should evacuate Boston to Miami..
to where? Oklahoma?
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Quoting angiest:


I think that was the A/B high moving west, not the one over the eastern US.


What does it mean for Earl in the short-term (3 days) for his track?
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Quoting 1992Andrew:
97L had the opportunity to ramp up convection but dry air was too much for baby fetus aborted Fiona. The wave behind the invest has a chance to be Fiona. Or the one behind that one. For sure, don't submit your ballot for 97L, gulf coast casters and admirers of yesterday's ECMWF model run.


way to count your chickens WAY before they are hatched

97L still has a great chance of being Fiona
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Quoting viman:
Is it my eyes, from watching computer screens too long, or is Earl making a westward wobble?


Your eyes are right, it has taken a westward jog. Probably just a wobble and will continue in WNW direction.
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Quoting StormW:
Keep in mind...Mother nature is just warming up.


I hear you, StormW. It's only August 30th. this train is just beginning to roll in.. I think?
Member Since: August 18, 2008 Posts: 0 Comments: 474
Quoting txsweetpea:
Has EARL turned North yet?


Not yet.. Sure hope it does soon though..
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Thanks for the posting of the long radar loop from PR. That is very helpful to me.

I place a straight edge of paper level right through the eye at the start of the loop, and then I can see the motion over the loop period better that way.
Member Since: July 12, 2007 Posts: 0 Comments: 6069
Quoting StormW:
Keep in mind...Mother nature is just warming up.


Yes Sir it is..
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1450. will40
Quoting HurricaneIsabel:
Vabeachhurricanes,

Hurricane party? lol if this steers too much left, this will be going in the record books. Strongest hurricane to hit the nc/va


its gonna have to stay stronggggggggggggggggggg to beat Hazel
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1449. GetReal
Quoting txsweetpea:
Has EARL turned North yet?




That depends upon your definition of north... IMO the answer is no....
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Quoting EastCarolina:


Its not going in the Gulf. The trough will steer Earl, it just depends on how much and when.


Yep I agree.. I believe it will make that turn sometime late tonight or early tomorrow morning.. But Im not sure how much of a turn it makes tho.. I'm not counting out a possible strike from the Carolina's and up to the Northeast.. I sure hope it recurves out to sea tho.. But we still got September, October, and maybe November..
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Ground floor APT here on a Barrier island off Long Island...

Definitely watching Earl. Stoked to see 20 foot waves not so stoked that my house is at 6 foot elevation.

Personally I think this going to be a real close call but a time to remember that just because its NY does not mean your safe...

Ill be prepping my backyard for trop winds Friday morning.
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Quoting HurricaneIsabel:
Vabeachhurricanes,

Hurricane party? lol if this steers too much left, this will be going in the record books. Strongest hurricane to hit the nc/va


looks like we are gonna need one! haha not lookin good
Member Since: September 6, 2007 Posts: 0 Comments: 6704
Quoting snowboy:
90 degrees and cooking here in Canada near Toronto. The famous trough nowhere in sight - we MAY see it late Thursday.

Interesting Forecaster Discussion for nearby Buffalo which speaks for itself:

Long term /Thursday through Sunday/...

At the start of the period strong ridging will still be in place
across the eastern third of the nation on Thursday. This is in part
due to Hurricane Earl...with the impacts of its outflow on the upper
troposphere helping to hold the ridge up and the approaching middle
latitude system at Bay for about a day longer than it would
otherwise. By Friday Earl will be gaining latitude and allow the
next Pacific system to spread east into the Great Lakes region. By
next weekend most model guidance allows a trough to dig into the
Great Lakes and northeast...although there are expected differences
with amplitude.


Looking at the details...on Thursday a weakening frontal boundary
will try to sag south towards the region...but will be held at Bay
and wash out owing to strong/persistent ridging over the northeast.
Model consensus among the past few runs of the GFS/ECMWF/gefs mean
give enough confidence to remove mention of precipitation for Thursday.
850mb temperatures up around +20c will bring one more very warm day. A
surface cold front is then forecast by GFS/European model (ecmwf) and most ensemble
members to sweep across the area late Thursday night or Friday. Will
continue with chance probability of precipitation for this period.
Based on your reports up there and mine here, I honestly don't think this trof is going to be all of that.
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Quoting myway:
Considering we may have a major hurricane impacting people. Can we at least stop the political stuff until there are no storms to watch. It never turns out well no matter what side you are on.


Exactly.
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1443. unf97
Quoting GetReal:



Azores high strengthening and nosing westward, north of Earl, preventing a more pronounced WNW to NW turn.... IMO

Watch out those in the Se Bahamas....


Yeah, it appears that the weakness left behind by Danielle is still there, but is shrinking, based on this map analysis. Very interesting.
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1442. hydrus
Quoting VAbeachhurricanes:


west again after a north wobble............ omg
Eventually, (this thing finally will max out) its path should smooth out. When informative stages, they wobble.jmo
Member Since: September 27, 2007 Posts: 1 Comments: 22643
Quoting obxnagshead:
Storm or anyone with knowledge...
When will he have a better grasp on Earl??
The OBX seems like we will be fine but if not we may be caught off guard. What are your thoughts on the future path, seems it changes with each model run. When will the next model runs be??
This morning we were really in the cone, now not so much. Do you think we will remain just outside of the cone from this point on???


Are you serious? You are in the bullseye in the OBX. I would start preparing.
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1440. viman
Is it my eyes, from watching computer screens too long, or is Earl making a westward wobble?
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Quoting Relix:
.1N
.4W

Heh, so much for the NW movement so far. 3 more hours of this and PR should get stronger winds.

So far here in Toa Baja getting gusty once more. Not many rains but definitely lots of breeze now. Preparing for the worst which should come soon!


I still think worse case scenerio for Puerto Rico is guest to Hurricane force. This storm would have to really truck due west and a little south IMO for it to shed sustained Hurricane force winds on the North Shore of Puerto Rico.

One Positive that no one seems to be mentioning is all that dry stable air to his north behind Danielle's old front? Doesn't anyone think this is going to hamper Earls strength in about 48 hours?
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Quoting snowboy:
90 degrees and cooking here in Canada near Toronto. The famous trough nowhere in sight - we MAY see it late Thursday.

Interesting Forecaster Discussion for nearby Buffalo which speaks for itself:

Long term /Thursday through Sunday/...

At the start of the period strong ridging will still be in place
across the eastern third of the nation on Thursday. This is in part
due to Hurricane Earl...with the impacts of its outflow on the upper
troposphere helping to hold the ridge up and the approaching middle
latitude system at Bay for about a day longer than it would
otherwise. By Friday Earl will be gaining latitude and allow the
next Pacific system to spread east into the Great Lakes region. By
next weekend most model guidance allows a trough to dig into the
Great Lakes and northeast...although there are expected differences
with amplitude.


Looking at the details...on Thursday a weakening frontal boundary
will try to sag south towards the region...but will be held at Bay
and wash out owing to strong/persistent ridging over the northeast.
Model consensus among the past few runs of the GFS/ECMWF/gefs mean
give enough confidence to remove mention of precipitation for Thursday.
850mb temperatures up around +20c will bring one more very warm day. A
surface cold front is then forecast by GFS/European model (ecmwf) and most ensemble
members to sweep across the area late Thursday night or Friday. Will
continue with chance probability of precipitation for this period.

Yea I just talked to a friend there & she said it was soo hot!
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1435. angiest
Quoting Hurricanes101:
The ridge moving westward is a good thing, it helps to open that slight weakness enough to help Earl turn NW

What we do not want is for the ridge to move NE


I think that was the A/B high moving west, not the one over the eastern US.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
1434. Or4590
Quoting CBConnie:
Thanks for the reply, Hurricane4life.....I live in Cape Breton, right beside the beach! I'm preparing for Earl, just incase! I was living in Halifax during Hurricane Juan, and it scared the living bejeesus out of me!


Damn...I thought I was the only Caper here...
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Has EARL turned North yet?
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Ok so Ive really got issues when it comes to understanding hurricanes on radar when it comes to rain. Having to mix in the spin with fwd motion really does me in.
I am in Eastern Puerto Rico (Humacao) and it has been pretty dry and windless for a while now. Safe to say the worst has passed or is everything south of St Croix going to make it's way in to PR?
Thanks!
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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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