97L continues to grow more organized; headed for Bahamas and Florida

By: Dr. Jeff Masters , 7:07 PM GMT on July 20, 2010

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A tropical wave (Invest 97L) between Puerto Rico and the Dominican Republic has continued to become more organized today, and is a threat to develop into a tropical depression as early as Wednesday morning. The disturbance has brought heavy rains of 8+ inches to Culebra and Vieques islands over the past day, and all of Puerto Rico and the Virgin Islands are under flash flood watches today. The storm could bring an additional 3 - 6 inches of rain to the islands over the next two days. The upper level low centered a few hundred miles north of the Dominican Republic is no longer bringing high levels of wind shear to 97L; wind shear has fallen to the moderate range, 10 - 15 knots, which should allow 97L to continue to develop today. Satellite images of 97L show a moderate area of steadily organizing thunderstorms, with curved bands developing to the north and east of the center. There are no signs of a surface circulation on satellite imagery or on the 10:38am EDT ASCAT pass. Surface observations show only light winds over Puerto Rico and the Dominican Republic, but the surface winds at Punta Cana on the eastern tip of the Dominican Republic have shifted to the west this afternoon, indicating that a surface circulation may be forming just north of that location. Long-range radar loops from San Juan do not show any evidence of a surface circulation. The Hurricane Hunter mission scheduled for today was canceled, but is scheduled to fly Wednesday afternoon.


Figure 1. Total precipitation from 97L as predicted by the 12Z (8 am EDT) July 20, 2010 run of the HWRF model. Image credit: Morris Bender, NOAA/GFDL.

Track Forecast for 97L
The storm is in a fairly straightforward steering current environment, and 97L should progress steadily to the west-northwest through Saturday. The rains from 97L's thunderstorms will bring the threat of isolated flooding to the Dominican Republic today and Wednesday, and to Haiti on Wednesday and Thursday. Heavy rains from 97L will begin moving into eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas on Wednesday, and South Florida can expect heavy rains to arrive as early as Thursday night. The latest suite of model runs from 8am EDT this morning (12Z) foresee a more northerly track for 97L into Central Florida. Several models develop 97L into a tropical storm, with both the GFDL and HWRF models predicting 97L will hit South or Central Florida as a tropical storm on Friday. Most of the models have 97L entering the Gulf of Mexico on Saturday, but the amount of time 97L has over the Gulf may be limited to a day or less if the storm ends up exiting into the Gulf near Tampa Bay. The NOGAPS model predicts a more southerly path across South Florida and into Louisiana.

Intensity Forecast for 97L
One factor potentially aiding development of 97L will be the Madden-Julian oscillation, which currently favors upward motion over the Gulf of Mexico and Caribbean. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. Also in favor of development are the warm ocean temperatures of 29°C. The SHIPS model predicts shear will stay in the moderate range, 10 - 20 knots, over the next five days. The primary detriment to development of 97L over the next three days will probably be the presence of dry, stable air in its path over the Bahamas, thanks to the upper-level low to the north of the Dominican Republic. If the center forms close to the coast of the Dominican Republic, the high mountains of Hispaniola may also be a problem for the storm. NHC is giving 97L a 60% chance of developing into a tropical depression by Thursday, which is a reasonable forecast. I think there is a 70% chance 97L will eventually become Tropical Storm Bonnie, sometime in the next five days. Sudden rapid development today or on Wednesday is unlikely, due to the dry air over the Bahamas. I put the odds of 97L making it to hurricane strength before reaching Florida at 30%, and I give a 20% chance it will be a hurricane in the Gulf of Mexico. The probability of 97L being a hurricane in the Gulf of Mexico will depend heavily upon how long the storm spends over land or interacting with land over the next four days, which is very uncertain.

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) Invest 97
2) A look ahead at the coming two weeks

Today's show will be about 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Jeff Masters

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828. unf97
Quoting JLPR2:
I know you guys are glued to 97L at the moment and I understand that but look at the SAL for a moment, confined to some patches in the CATL and to the north of the Cape Verde islands, looks like the blob off the coast has a nice clearing.



yes, the SAL out there is definitely waning. The new CV wave in time I believe will have a very decent chance to develop in the coming days.
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827. DEKRE
Post 808:

See Link

Straight copy
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When do the next set of models coem out 8 right?
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824. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15670
Quoting AstroHurricane001:


Taz, did you write this or did someone on storm2k write it?



some one us i was this shearing it
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this is one predicted path , from NOGAPS,is it one to worry about Link
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There, is everybody happy now? Absolutely no shear. If I wanted this much nagging, I would....never mind!!!! Someone may be watching.

Member Since: July 17, 2009 Posts: 71 Comments: 26117
Quoting weatherwart:


Okay, I did. Is that a pressure gradient? I'm really not sure what I'm looking at, patrap. Higher pressure area? Help, please?


Steering Layer routes are between the isobars
Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting HarleyStormDude52:
according to the dynamic models I am not going to get to run on generator and grill out with my neighbors!!!!!!


not looking like it.....but, hurricane season has just begun...
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Quoting TexasGulf:


I wouldn't cancel. You're far enough North from the projected path. Melbourne may get some wind and tropical rain, some really cool waves on the beach but otherwise you'll be fine.

If your vacation isn't until next weekend, this system (soon to be known as Hurricane Bonnie) will be West of you by then. No worries. Enjoy your trip. Just know that I am sometimes wrong... but even still this shouldn't amount to more than a Cat-1 at worst until it enters the Gulf.
I was also about to suggest, cancellation the day of arrival if it looks like u will be going into a hit. But that presupposes u will not be getting there until Friday or Saturday.
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Quoting Tazmanian:
Last week was one in which frontal lows are more likely to develop into tropical cyclones than tropical waves. This phenomenon is also more likely to happen in an El Nino year than a year like 2010. Reliable models also did not foresee any development. Putting all these pieces together, my forecast was for no development.

Overall, not to brag, this forecast was executed very well. No tropical waves threatened to develop, and no frontal lows looked promising either. My grade for last week is an A.

You can see last week's at this thread:
viewtopic.php?f=31&t=108544

Onto this upcoming week....

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

Current situation and models

As we look at the current situation, there are no tropical cyclones in the Atlantic. There are, however, a few interesting areas that may be worth watching. The Central and Western Caribbean has a large disturbance that some models are hinting may develop, and the NHC gives a 10% chance of development here over the next 48 hours. There is also a tropical wave near the northern Leeward Islands that some models also want to develop, with the NHC also giving a 10% chance of development over the next 48 hours. However, the Euro model, which did a great job on Alex and TD #2, does not hint at development at this time. That said, the next run comes later tonight, and I will not see the run until I wake up tomorrow at the earliest.

Some members here are also talking about a new tropical wave coming off Africa - however, it looks like it is weakening at this time and I do not foresee this system developing, nor do any models

Looking down the road, at the weekend, the Euro model does hint at a strong tropical wave coming off the African coast. That is one thing, but will it develop? Time will tell.

Recent history

Since 1995, there have been five new tropical storms develop:

Cesar in 1996
Franklin in 2005
Gert in 2005
Cristobal in 2008
Dolly in 2008

That's a two-storm drop from last week, which may seem contradictory as we near August. But then, remember that of seven tropical storms for the period of last week, five came from frontal lows. Of this week's new five, only one came from a frontal low: Cristobal. So tropical wave developments actually increase slightly, from two last week to four this week.

Also, all of these five storms that developed were in "home-grown" areas. Franklin and Cristobal came just off the southeast coast, and Gert and Dolly near the Yucatan. Cesar appears to be an outlier, forming in the southeastern Caribbean - in fact, it was the first storm to develop in that area for this upcoming week since Hurricane Anna in 1961.

Only one of these storms, Dolly, became a hurricane this upcoming week (though Cesar became one shortly after this period, but that's for next week) - doing so in the Gulf of Mexico after forming into a tropical storm in the western Caribbean. Dolly then even went on to become a C2! Franklin and Cristobal were close, but couldn't quite pull it off as they headed out to sea, away from the East Coast. And while Gert developed in the Bay of Campeche, a combination of forming from a very disorganized disturbance and having little time to strengthen crippled its chances of getting stronger than 45 mph.

There were also six storms previously intact coming into this week:

Chantal in 1995
Danny in 1997
Danny in 2003
Emily in 2005
Beryl in 2006
Bertha in 2008

Chantal, 2003 Danny, Beryl, and Bertha were already at rather northerly latitudes. Beryl was just developing and would reach 60 mph, but no higher before clipping Nantucket and heading out to sea. The other three storms of these four would get no stronger and weaken before dissipating or becoming extratropical. It should be noted that Danny in 1997 also made landfall in Alabama on the 19th, weakened over land, and then re-strengthened into a tropical storm off the East Coast during this period. Like Beryl, maximum winds reached 60 mph as it neared Nantucket.

Only Emily remained in a tropical latitude the entire time, and re-strengthened from a minimal hurricane into a C3 over the Gulf of Mexico before making landfall in northern Mexico.

So what does this all tell us?

While tropical waves have a slightly better chance of developing than last week, the chances still aren't that good. If one does form, the best bet is in an area close to home. And if you're looking for a storm to form into a hurricane, the Gulf of Mexico remains as ripe as last week - Gert notwithstanding.

Back to looking ahead

So let's go back to this week. Tropical waves exist in the Caribbean and northern Leeward Islands that some models see development with. These are favorable areas, although the Leeward Islands wave probably will not develop until at least Thursday due to shear, and at this point be likely closer to the Bahamas. The reliable Euro, however, does not see development with either of these two. The wave currently coming off Africa would be expected to fizzle around this time, as would the strong wave the Euro sees coming off around probably Saturday.

The Euro is very reliable, and this week is still a very shaky week for development. However, seeing two waves in these areas near home makes my prediction for this week a bit tougher than last week. All this put together, however, and I think the wave in the Caribbean will be too slow to develop and run into land. I also think the Leeward Islands wave will struggle as shear increases. It may try to make a comeback by Thursday, but it could also have problems with land interaction around that time. The models that try to develop this system include the GFS, the NAM, and their supporting ensembles - not the most reliable ones in the world. I would also like to see what the NOGAPS and UKMET say before predicting this disturbance to develop.

Therefore, I predict no tropical cyclone development this week.

Confidence in this prediction is about 80%.

-Andrew92


Taz, did you write this or did someone on storm2k write it?
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815. JLPR2
I know you guys are glued to 97L at the moment and I understand that but look at the SAL for a moment, confined to some patches in the CATL and to the north of the Cape Verde islands, looks like the blob off the coast has a nice clearing.

Member Since: September 4, 2007 Posts: 7 Comments: 8690
The HWRF path above is unlikely. It is too close to the area that gets that kind of path. It's off by at least fifty miles without even starting to discuss it.
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Quoting Grothar:


Can't you ever say anything nice? LOL
No.


LOL!
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Re: Post #756

Thanks WathchingThisOne, that was EXTREMELY helpful!!!
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Quoting Orcasystems:
Models take it to at least a CAT 1



AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI


yep..
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting Patrap:
97L Floater - Rainbow Color Infrared Loop

Check the MSLP box


Okay, I did. Is that a pressure gradient? I'm really not sure what I'm looking at, patrap. Higher pressure area? Help, please?
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commet re move
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Quoting CaicosRetiredSailor:
Afternoon Baha,

Steady 15-20 mph from East today.

My bummer for today is that after all our talk about Wx station, I have been troubleshooting mine today.
the digital Barometer is not working, I thought it just needed to be re-set but it won't take initialize... going through tests and spares now. Of course I have my old analog one which I had with me 30 yrs ago in Bahamas and it still works.

CRS


GReat... why is it they only malfunction just when u need them to work??? lol

Hope u can get it back online by tomorrow a.m.

We've been pretty steady at around 15 here today. I'll be interested to see how much the wind has picked up by this time tomorrow...
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according to the dynamic models I am not going to get to run on generator and grill out with my neighbors!!!!!!
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Quoting Patrap:
Plan of the Day

000
NOUS42 KNHC 201445
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1045 AM EDT TUE 20 JULY 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 21/1100Z TO 22/1100Z JULY 2010
TCPOD NUMBER.....10-050

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (NORTH OF HISPANIOLA)
FLIGHT ONE -- TEAL 70
A. 21/1800Z
B. AFXXX 01BBA INVEST
C. 21/1400Z
D. 21.0N 70.0W
E. 21/1700Z TO 21/2100Z
F. SFC TO 10,000 FT

FLIGHT TWO -- NOAA 49
A. 22/0000Z
B. NOAA9 02BBA SURV
C. 21/1730Z
D. NA
E. NA
F. 41,000 TO 45,000 FT


FLIGHT THREE -- TEAL 71
A. 22/0600Z, 1200Z
B. AFXXX 0303A CYCLONE
C. 22/0400Z
D. 22.0N 72.0W
E. 22/0500Z TO 22/1200Z
F. SFC TO 15,000 FT

2. SUCCEEDING DAY OUTLOOK: CONTINUE 6-HRLY FIXES IF
SYSTEM REMAINS A THREAT. A POSSIBLE G-IV
MISSION FOR 23/0000Z.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

Bold is the Gulfstream 2 G-4 High Flyer.

The other Are C-130 HH flights with times on station and wheels up
I don't believe that the flight you bolded is our normal G-IV flight...the type that looks at the environment ahead of the cyclone. Rather..this flight is a surveillance flight of the developing TD to be, but at high altitudes, as opposed to the low-level Hurricane Hunters.
.
.
Of course, I could be wrong. My source is The Weather Channel, who mentioned this particular mission.
Member Since: August 3, 2005 Posts: 10 Comments: 5578
WOW, marching (band :P) for 8 and a half hours in 95 degree temps has worn me out, so besides that I'm mainly sleeping in my free time instead of being here. Where the HECK did that code red come out of lol. Of course the tropics heat up right as I get back to school.
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Quoting MiamiHurricanes09:
SHIPS shows only 15 knots over 97L. CIMSS has been doing poorly as of late.


Can't you ever say anything nice? LOL
Member Since: July 17, 2009 Posts: 71 Comments: 26117
Models take it to at least a CAT 1



AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
The areas north of Cuba were relatively dry for awhile. Bonnie says: welcome to my world.
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Quoting Patrap:


They wacko .. No one is gonna get a 5 day notice.

They have beaucoup Private Met offices on the situ. But they have to act on their info.

BP aint known for Brillance nor saftey,..

I worked for Chevron offshore in the Mid 90's and safety was always the Number 1 issue.


If BP can keep their Vessels in Place.
They will as long as Possible.

The USCG and Admiral Allen had to force the SOB's to Produce a Hurricane Plan 6 weeks ago.


Actually, the deepwater horizon crew valued safety enough to make a rap video about it:
Link
Not sure if that is a good or bad thing, I just know w/o the captions I wouldn't be able to understand wtf they are saying.
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some commets about the big wave


Link
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Quoting leo305:
Mayfield said no models take it up to hurricane strength, and that most only develop it into a depression, and only some into a Tropical storm.

That doesn't seem accurate to me..


About half the models take it into the gom with hardly any land interaction.

All the way from PR to Louisiana and not a hurricane? I don't think so.
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Are the oil rigs shutting down? they might have to deal with a ts soon
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Quoting Patrap:
18z Early Cycle NHC model tracks
Invest97
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)




imn confused I thought the models came out every 6 hours. Shouldnt they come out at 8
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795. txjac
Quoting Weather456:
My next blog was to be this morning but a severe lightining strike from last associated with 97L damage the power grid and the entire island of St. Kitts is without power. I am blogging from a mobile device and hope to get my updates back up when power is restored. The system also caused flooding and disruption to land transportation. Its just a mud mess down here.


Stay safe weather ...hope power comes back soon and all goes back to usual soon ...
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NASA MSFC Viewer 97L
Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting BahaHurican:
unfortunately we've had our moments here in Nassau as well.... :o(


It happened in the Northern Virginia suburbs of D.C. a couple Summers ago. A strong line of thunderstorms rumbled through from west to east leaving 50K+ people without electrical power for 1-3 DAYS!

Who needs terrorists when Mother Nature can be so disruptive.
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Quoting boteman:


...at this time. The next model run could very well change.


There are multiple models that take it to Cat 1
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Royalpalmbeaches: High pressure. It's possibly weaker over Cuba. Although a few paths of SFWMD show it going over Cuba!
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Quoting boteman:


...at this time. The next model run could very well change.


yea but at this time, most models do develop it into at least a TS, and SHIPS takes it up to Hurricane strength
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting CaicosRetiredSailor:
Afternoon Baha,

Steady 15-20 mph from East today.

My bummer for today is that after all our talk about Wx station, I have been troubleshooting mine today.
the digital Barometer is not working, I thought it just needed to be re-set but it won't take initialize... going through tests and spares now. Of course I have my old analog one which I had with me 30 yrs ago in Bahamas and it still works.

CRS




I have to reload the software onto a spare laptop for mine... I crashed an old machine it was connected to..and never reloaded it :)
Member Since: October 1, 2007 Posts: 81 Comments: 26511
97L Floater - Rainbow Color Infrared Loop

Check the MSLP box
Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting Royallypalmbeaches:
Hello, come in often to get perspective on the weather. Last night I saw the area east of Fl. was unfavorable for development. and then move through Cuba and head up into the GOM. What happened? Have a 4 day stay in Melbourne on the Ocean. Not not sure whether to cancel.


I wouldn't cancel. You're far enough North from the projected path. Melbourne may get some wind and tropical rain, some really cool waves on the beach but otherwise you'll be fine.

If your vacation isn't until next weekend, this system (soon to be known as Hurricane Bonnie) will be West of you by then. No worries. Enjoy your trip. Just know that I am sometimes wrong... but even still this shouldn't amount to more than a Cat-1 at worst until it enters the Gulf.
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Quoting leo305:
Mayfield said no models take it up to hurricane strength, and that most only develop it into a depression, and only some into a Tropical storm.

That doesn't seem accurate to me..


...at this time. The next model run could very well change.
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Member Since: July 3, 2005 Posts: 423 Comments: 128240
Another rainy day in Grand Cayman. I think it just may rain all summer - I feel bad for our visitors but it is such a nice treat from the overwhelming heat of July. Definitely feels like hurricane weather
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Quoting bjdsrq:


St Kitts is amazing. I can't imagine too many places where a summer-tstorm lightning strike would take out the whole grid, but St Kitts is one of those places. My guess is the grid looks something like this:
Link
unfortunately we've had our moments here in Nassau as well.... :o(
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Later everyone!
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Afternoon Baha,

Steady 15-20 mph from East today.

My bummer for today is that after all our talk about Wx station, I have been troubleshooting mine today.
the digital Barometer is not working, I thought it just needed to be re-set but it won't take initialize... going through tests and spares now. Of course I have my old analog one which I had with me 30 yrs ago in Bahamas and it still works.

CRS


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Quoting Grothar:
Still some shear!





http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8sht.GIF


At this point I would look more to the shear in satellite pics than models.. shear is easy to spot. There is still some strong shear above 22N in the current visible loop but the cloud tops south of 21N look intact except outflow
Member Since: September 1, 2009 Posts: 23 Comments: 1007

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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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