Bill is gone; Invest 92 pops up

By: Dr. Jeff Masters , 2:08 PM GMT on August 24, 2009

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Hurricane Bill is no more. The hurricane swept past Canada's Nova Scotia province Sunday afternoon, then made landfall early this morning in southeastern Newfoundland as a borderline tropical storm/Category 1 hurricane. Bill's waves claimed two lives over the weekend, a 54-year old swimmer that drowned in Florida, and a 7-year old girl in Maine that got swept into the sea by a big wave. The first death of the 2009 Atlantic hurricane season occurred on August 16, when a swimmer drowned in the rough surf from Tropical Storm Claudette at Pananma City Beach, FL.

Nova Scotia misses a direct hit
The center of Bill scooted parallel to the coast of Nova Scotia Sunday afternoon, and never quite came onshore. Since the storm's forward speed was so rapid--about 35 mph--this resulted in a highly asymmetric wind distribution. Since the top winds of a hurricane include the forward motion of the storm, Bill's top winds of 85 mph observed in the offshore, right front quadrant of the storm meant that the winds on the weak side of the storm, over Nova Scotia, were 85 mph minus 35 mph, or just 50 mph. Winds along most of the coast stayed below 39 mph, the borderline for tropical storm-force winds. The strongest winds measured in Canada were at Sable Island, which lies 150 miles offshore of Nova Scotia. Winds on the island hit 61 mph, gusting to 77 mph, between 4 - 5 pm ADT Sunday afternoon. A few islands along the Nova Scotia coast, such as Beaver Island and Hart Island, reported sustained winds of 39 - 40 mph. The big story for Nova Scotia was the waves from Bill. Buoy 44258 at the mouth of Halifax Harbor recorded significant wave heights of 29.5 feet and maximum wave heights of 49 feet as Bill passed 50 miles offshore. The buoy recorded top sustained winds of 35 mph, gusting to 51 mph. The waves combined with a 1.5 - 3 foot storm surge flooded many coastal roads. Buoy 44150, about 160 miles offshore of of the southwest tip of Nova Scotia, was in the east eyewall of Bill between 10 - 11 am ADT, and reported sustained winds of 62 mph, gusting to 85 mph, with significant wave heights of 44 feet. The buoy recorded a maximum wave height of 87 feet, according to Environment Canada. The highest official rain report on Nova Scotia was 2.6" (65 mm) at Yarmouth. Rainfall cause some localized flooding and road damage. Bill's winds cut power to about 40,000 people at the height of the storm. At Peggys Cove, three men were hit by a giant wave but were not hurt. A gift shop and attached home in the village were swept off of their foundation.

Newfoundland gets hit, but damage is minor
The southeast corner of Newfoundland took a direct hit from Bill. The storm made landfall early this morning as a borderline tropical storm/Category 1 hurricane. Top winds on the island were measured at Cape Race, which recorded sustained winds of 58 mph, gusting to 76 mph, between 1:30 and 2:30 am NDT. A storm surge of 1.2 meters (4 feet) was estimated by Environment Canada for Placentia Bay where Bill made landfall. Damage was minor on Newfoundland, with no major flooding reported. Bill dumped up to three inches of rain on Newfoundland.


Figure 1. The eye of Hurricane Bill on August 19 at 2157 UTC, from a NOAA P-3 Hurricane Hunter aircraft flying at 10,000 feet. Photo credit: Jack Parrish of NOAA's Aircraft Operations Center.

Kelvin-Helmholtz instability waves in the eye of Bill
Flight Director Jack Parrish of NOAA's Aircraft Operations Center snapped a cool photo in the eye of Hurricane Bill on Friday, showing the existence of a Kelvin-Helmholtz instability wave (Figure 1). The photo was taken on August 19 at 2157 UTC, from a NOAA P-3 Hurricane Hunter aircraft flying at 10,000 feet. The photo is taken looking WNW towards the eyewall. The towering clouds of the eyewall extend up to 50,000 - 55,000 feet in the photo, and the ocean surface is not visible, due to stratocumulus clouds covering the bottom of the eye. The center of the photo shows that the top of one of these stratocumulus clouds has a feature that looks like a breaking wave in the ocean. Well, that is an example of a breaking wave in the atmosphere known as a Kelvin-Helmholtz instability wave. The atmosphere behaves as a fluid, and thus has wave-like motions. When there is a sudden change of wind speed along the top of a cloud (wind shear), the flow can become unstable and cause breaking waves to form. One can see Kelvin-Helmholtz in the sky several times per year, and several alert wunderphotographers have uploaded photos of these waves over the years. However, it is uncommon to see these waves in the stratocumulus clouds covering the eye of a hurricane.


Figure 2. Water vapor satellite image for 8:15 am EDT 8/24/09. A tropical wave is approaching the Northern Lesser Antilles Islands, but is running into high wind shear from an upper-level cold low to the west of it. Image credit: NOAA/SSD.

Tropical wave approaching Lesser Antilles becomes Invest 92
A tropical wave with a moderate amount of shower activity is moving west-northwest at 20 - 25 mph and is approaching the northern Lesser Antilles Islands. This wave was designated "Invest 92" (92L) by NHC this morning. The wave is under about 20 - 30 knots of wind shear due the strong upper-level winds from the west. These winds are being created by the counter-clockwise flow of air around an upper-level cold-cored low north of Puerto Rico (Figure 2). This low is expected to move west-southwest and slowly weaken over the next two days, allowing shear to drop to the moderate 10 - 20 knot range beginning Tuesday night, according to the SHIPS model. By Wednesday, the upper low is predicted to be weak enough and far enough away from 92L that it will have a chance to develop. Most of the models show some degree of development of 92L by Thursday, when it is expected to be a few hundred miles off the coast of South Carolina. This wave could turn northward and give a wet weekend to New England, though it is too early to be confident of this. NHC is giving 92L a low (less than 30% chance) of developing into a tropical depression by Wednesday morning. The upper-level low will create plenty of wind shear and dump cold, dry air into 92L over the next two days, so Wednesday is probably the earliest we can expect the system to begin organizing into a tropical depression.

Several models predict the development of a tropical wave coming off the coast of Africa late this week.

I'll have an update Tuesday.

Jeff Masters

Beach Wall wave 1 (BeachBecky)
Waves from Hurricane Bill crashing on the sea wall during high tide in Lynn, MA
Beach Wall wave 1
Hurricane Bill Waves Day 2 # 9 (RIWXPhoto)
Hurricane Bill Waves Day 2 # 9
Kelvin-Helmholtz Instabilities (btangy)
Kelvin-Helmholtz Instabilities to the S of Boston. Wavy like pattern in clouds is caused by a difference in winds between the cloud layer and the layer just above (called wind shear). The manifestation of this at the top of the altostratus deck is quite a beautiful and rare sight!
Kelvin-Helmholtz Instabilities

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Outlier experimental model from CIMSS. Performed so-so on past hurricanes, but have seen no data on developing systems. Just another view which is probably way off base.

CRAS45NA
Member Since: September 23, 2005 Posts: 15 Comments: 11347
sorry my mistake with the dates
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1546. IKE
Here's where the HWRF centers it at 6 hours into it's run....centered near 22 north....GFDL has it centered between 21-22 north on the start of it's run too..




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1545. KEEPEROFTHEGATE (Mod)
good morning ike those things will change a few times before its right
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1543. IKE
Quoting BobinTampa:


Labor Day is the weekend after this coming weekend.



Yeah...he's got the wrong weekend and besides, looks like 92L may stay offshore anyway.
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Quoting stoormfury:
Looks like a labor day hurricane for the northeast


Labor Day is the weekend after this coming weekend.

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1541. IKE
Quoting KEEPEROFTHEGATE:
157

WHXX01 KWBC 250809

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

0809 UTC TUE AUG 25 2009



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL922009) 20090825 0600 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

090825 0600 090825 1800 090826 0600 090826 1800



LAT LON LAT LON LAT LON LAT LON

BAMS 18.9N 61.5W 21.3N 64.8W 23.7N 67.3W 26.0N 69.5W

BAMD 18.9N 61.5W 21.0N 63.6W 23.1N 65.3W 24.9N 67.0W

BAMM 18.9N 61.5W 20.8N 64.2W 22.5N 66.2W 24.2N 68.1W

LBAR 18.9N 61.5W 20.7N 63.9W 22.4N 66.2W 23.9N 68.0W

SHIP 25KTS 30KTS 36KTS 46KTS

DSHP 25KTS 30KTS 36KTS 46KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

090827 0600 090828 0600 090829 0600 090830 0600



LAT LON LAT LON LAT LON LAT LON

BAMS 28.1N 71.1W 31.4N 72.6W 34.0N 72.4W 37.3N 67.8W

BAMD 26.4N 68.4W 28.8N 69.9W 31.8N 69.8W 36.8N 65.5W

BAMM 25.7N 69.6W 28.1N 71.3W 30.8N 71.1W 34.9N 67.1W

LBAR 25.3N 69.3W 27.1N 70.6W 28.9N 71.5W 30.8N 72.2W

SHIP 52KTS 65KTS 73KTS 81KTS

DSHP 52KTS 65KTS 73KTS 81KTS



...INITIAL CONDITIONS...

LATCUR = 18.9N LONCUR = 61.5W DIRCUR = 295DEG SPDCUR = 19KT

LATM12 = 17.1N LONM12 = 58.0W DIRM12 = 294DEG SPDM12 = 21KT

LATM24 = 15.9N LONM24 = 54.0W

WNDCUR = 25KT RMAXWD = 50NM WNDM12 = 20KT

CENPRS = 1012MB OUTPRS = 1014MB OUTRAD = 120NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN


Can you send a memo to the BAM model suite? There's nothing at 18.9N and 61.5W. It's at least 100 miles north of there.

I see it near 21.0N and 61.6W.
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1540. Engine2
Quoting stoormfury:
Looks like a labor day hurricane for the northeast

Huh? Models please?
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Looks like a labor day hurricane for the northeast
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Looks like father like son.
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1537. WxLogic
Quoting wunderkidcayman:

and that is for what 92L,93L or possible 94L


This would be for all 3... you'll see the steering for 92L is WNW, for 93L is W and for the AOI (better not use 94L yet to avoid confusion... hehe) is W also to a little WSW at times.
Member Since: August 14, 2008 Posts: 4 Comments: 5038
1535. KEEPEROFTHEGATE (Mod)
157

WHXX01 KWBC 250809

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

0809 UTC TUE AUG 25 2009



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL922009) 20090825 0600 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

090825 0600 090825 1800 090826 0600 090826 1800



LAT LON LAT LON LAT LON LAT LON

BAMS 18.9N 61.5W 21.3N 64.8W 23.7N 67.3W 26.0N 69.5W

BAMD 18.9N 61.5W 21.0N 63.6W 23.1N 65.3W 24.9N 67.0W

BAMM 18.9N 61.5W 20.8N 64.2W 22.5N 66.2W 24.2N 68.1W

LBAR 18.9N 61.5W 20.7N 63.9W 22.4N 66.2W 23.9N 68.0W

SHIP 25KTS 30KTS 36KTS 46KTS

DSHP 25KTS 30KTS 36KTS 46KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

090827 0600 090828 0600 090829 0600 090830 0600



LAT LON LAT LON LAT LON LAT LON

BAMS 28.1N 71.1W 31.4N 72.6W 34.0N 72.4W 37.3N 67.8W

BAMD 26.4N 68.4W 28.8N 69.9W 31.8N 69.8W 36.8N 65.5W

BAMM 25.7N 69.6W 28.1N 71.3W 30.8N 71.1W 34.9N 67.1W

LBAR 25.3N 69.3W 27.1N 70.6W 28.9N 71.5W 30.8N 72.2W

SHIP 52KTS 65KTS 73KTS 81KTS

DSHP 52KTS 65KTS 73KTS 81KTS



...INITIAL CONDITIONS...

LATCUR = 18.9N LONCUR = 61.5W DIRCUR = 295DEG SPDCUR = 19KT

LATM12 = 17.1N LONM12 = 58.0W DIRM12 = 294DEG SPDM12 = 21KT

LATM24 = 15.9N LONM24 = 54.0W

WNDCUR = 25KT RMAXWD = 50NM WNDM12 = 20KT

CENPRS = 1012MB OUTPRS = 1014MB OUTRAD = 120NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN
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1534. KEEPEROFTHEGATE (Mod)
T.C.F.A 92L
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1533. IKE
6Z GFDL on 92L...


6Z HWRF on 92L...


System appears to be forming further north than where it was centered last night. Looks like another Bill track to me.
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Quoting WxLogic:
Current steering supports a WNW for the time being:


and that is for what 92L,93L or possible 94L
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1531. WxLogic
Current steering supports a WNW for the time being:

Member Since: August 14, 2008 Posts: 4 Comments: 5038
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morning all
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yea pretty much guaranteed to swing north.
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thank you for the answers I had thought they started at one and went through all the numbers in the 20s 30s etc and was confused how they went through 90 some invests in just a few weeks without me noticing.....DOH!!!
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1526. FLBlake
Quoting TightLines305:
Mysterious Tubular Clouds Defy Explanation

http://www.wired.com/wiredscience/2009/08/morninggloryclouds/



Roll Form Cloud
Link
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Good News for us in S.FL.

looks like south Florida dodged another one.

Member Since: March 19, 2009 Posts: 0 Comments: 1421
the area in the catl near with a low pressure near 14n 35w is far from organising into something tropical in the near future. there is no convergence or divergence and convection with this system. what it has going for it is a strong 850mb vorticity, low vertical shear and an anticyclone just to the west. development will be slow to occur
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67/22 is about where the center could be, the convection has blown off to the NW?
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Quoting zebralove:
I have a question for everyone, How do they decide the number for Invests? Just a few weeks ago they were naming invests 2 and 3 now the invests are 92 and 93. I have only been learning just over a year now and I remember last year they were numbering invests at 93 94. Can anyone tell me how they get numbered?
Confused the heck out me as well. I thought they started with 90 and went through to 99 before coming back to 90.

Oh... and good morning folks

British Isles, Ireland - How goes it??
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1519. Skyepony (Mod)
Here's some pretty good pictures of the lightning that scrubbed this morning's launch.
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1518. WxLogic
Quoting zebralove:
I have a question for everyone, How do they decide the number for Invests? Just a few weeks ago they were naming invests 2 and 3 now the invests are 92 and 93. I have only been learning just over a year now and I remember last year they were numbering invests at 93 94. Can anyone tell me how they get numbered?


They move sequentially... 1, 2, 3, etc... then once they get to 9... then they start over with 0, 1, 2, etc...
Member Since: August 14, 2008 Posts: 4 Comments: 5038
1517. IKE
If 92L is about 300 miles NE of San Juan and it's moving WNW, it should pass north of the Bahamas.
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Quoting TightLines305:
Mysterious Tubular Clouds Defy Explanation

http://www.wired.com/wiredscience/2009/08/morninggloryclouds/


KEWL !!!!
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good morning we have 92L I knew that 93L would form and look like we will soon have 94L from that east atlantic wave/low and just maybe 95L from that african wave/low

Link

Link

Link
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1514. WxLogic
Indeed... they're drawing the Red circle as we speak.
Member Since: August 14, 2008 Posts: 4 Comments: 5038
and then POOF!
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I have a question for everyone, How do they decide the number for Invests? Just a few weeks ago they were naming invests 2 and 3 now the invests are 92 and 93. I have only been learning just over a year now and I remember last year they were numbering invests at 93 94. Can anyone tell me how they get numbered?
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1511. IKE
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT TUE AUG 25 2009

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

A LARGE AREA OF CLOUDINESS AND THUNDERSTORMS CENTERED ABOUT 300
MILES NORTHEAST OF SAN JUAN PUERTO RICO IS ASSOCIATED WITH A
TROPICAL WAVE INTERACTING WITH AN UPPER-LEVEL LOW. EARLY MORNING
VISIBLE SATELLITE IMAGES SUGGEST THAT THE WAVE HAS BECOME A LITTLE
BETTER ORGANIZED. UPPER-LEVEL WINDS ARE FORECAST TO BECOME MORE
CONDUCIVE FOR DEVELOPMENT DURING THE NEXT DAY OR SO AS THE SYSTEM
MOVES WEST-NORTHWESTWARD AROUND 20 MPH. THERE IS A HIGH
CHANCE...GREATER THAN 50 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS. A RECONNAISSANCE
AIRCRAFT IS SCHEDULED TO INVESTIGATE THE AREA THIS AFTERNOON.
INTERESTS IN THE BAHAMAS AND THE TURKS AND CAICOS ISLANDS SHOULD
MONITOR THE PROGRESS OF THIS SYSTEM.

AN AREA OF DISTURBED WEATHER OVER THE SOUTHWESTERN CARIBBEAN SEA IS
ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE NEAR THE COAST AT THE
BORDER BETWEEN COSTA RICA AND NICARAGUA. DEVELOPMENT OF THIS
SYSTEM IS NOT ANTICIPATED BEFORE IT MOVES INLAND OVER CENTRAL
AMERICA TODAY. THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE. LOCALLY HEAVY RAINFALL IS
POSSIBLE OVER NICARAGUA AND COSTA RICA DURING THE NEXT DAY OR SO AS
THIS SYSTEM MOVES WESTWARD INTO THE EASTERN PACIFIC OCEAN.

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

$$
FORECASTER BROWN
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Mysterious Tubular Clouds Defy Explanation

http://www.wired.com/wiredscience/2009/08/morninggloryclouds/
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it looks like the area at 35w is becoming a bit more interesting. let's see if it can build more convection
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Quoting Greyelf:


Always funny seeing named highs and lows. Those silly Europeans.


Do they retire any highs or lows? :P
Member Since: August 18, 2008 Posts: 0 Comments: 628
It looks like 92L should become a depression soon, having seemingly overcome the shear, which should relax. It looks to follow a path similar to Bill but maybe a little further west. Still too early to say exactly how far west it will move before swinging towards the north and northeast.

93L is doing what a late August low-latitude disturbance in the SW Caribbean should do...move almost due west, cross central America and move into the Pacific, where it should develop further. If it was October or November, that system would have swung more towards the north.

That low-level circulation near 14N and 34W is interesting...very broad but very little convection, mostly a swirl of low clouds. If convection doesn't develop over the next day or so, it'll probably spin down slowly, but it's certainly worth watching for now, as is the wave coming off Africa.
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1505. Greyelf
Quoting HadesGodWyvern:


right overland U.K. in the coming hours


Always funny seeing named highs and lows. Those silly Europeans.
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morning
the tropical wave at 35W has lost most of it's convection due to very dry air in the vicinity. meanwhile very robust tropical wave is about to exit the african coast. it is carrying 1009mb low with it . most of the global models are hinting of some form of development in the CATL the next few days. the wave at35W is a fairly large one ,with an elongated area of low pressure
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Good Morning all. Need Coffee! No go shuttle?
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1502. WxLogic
Morning.. 456..
Member Since: August 14, 2008 Posts: 4 Comments: 5038
1500. WxLogic
Good morning...
Member Since: August 14, 2008 Posts: 4 Comments: 5038
Good Morning all

Tropical Invests 92L and 93L

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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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