Alex building an eyewall, still not a hurricane

By: Dr. Jeff Masters , 7:34 PM GMT on June 29, 2010

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Tropical Storm Alex is slowly building an eyewall, which is now more than 50% complete, according to recent satellite imagery and microwave images (Figure 1.) Satellite loops show a slot of dry air is spiraling into the center of the storm, and until this dry slot gets closed off, Alex will not be able to intensify significantly. Alex's heavy thunderstorms and low level spiral bands continue to slowly increase, but upper-level outflow is mediocre to the north and east, and absent elsewhere. The Hurricane Hunters are in the storm and have not found any hurricane-force winds at the surface yet.


Figure 1. Microwave "radar in space" image taken at 10:11 am CDT Tuesday June 28, 2010, showing that Alex had built an eyewall a little more than 50% complete. Image credit: Navy Research Lab.

Impacts
Alex is already bringing bands of heavy rain to the coasts of Texas and Mexico, as seen on the Brownsville, Texas radar. Hurricane local statements with projections for how Alex will affect the coast are now being issued by the National Weather Service in Brownsville and Corpus Christi. Since Alex is a large storm, it will have a storm surge that will affect most of the South Texas coast. NHC is giving a 40% - 60% chance of a storm surge of at least 3 feet affecting the Brownsville area, and 10% - 30% chance the surge will exceed 5 feet. In theory, a Category 2 hurricane moving WNW at 5 mph can bring a storm surge of up to 8 - 9 feet to the South Texas coast (Figure 2.) However, Alex is now unlikely to get that strong, and the surge should be less. Flooding damage from the expected 6 - 12 inches of rain from Alex will also be a major concern, as will wind damage. The combined wind, surge, and flooding damage from 2008's Hurricane Dolly, which hit near Brownsville, were about $1.05 billion. Dolly was a Category 2 hurricane offshore that weakened to a Category 1 hurricane with 85 mph winds when it made landfall. I expect Alex will be similar in its impacts to Dolly, though Alex's storm surge damage is likely to be greater. If Alex hits more than 50 miles south of the Texas border, as currently appears likely, the damage will be far less, since this region of the coast is relatively sparsely populated.


Figure 2. Maximum Water Depth (storm tide minus the elevation of the land it is passing over) computed using the primary computer model used by the National Hurricane Center (NHC) to forecast storm surge--the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. The accuracy of the SLOSH model is advertised as plus or minus 20%. The "Maximum Water Depth" image shows the water depth at each grid cell of the SLOSH domain. Thus, if you are inland at an elevation of five feet above mean sea level, and the combined storm surge and tide (the "storm tide") is ten feet at your location, the water depth image will show five feet of inundation. This Maximum of the "Maximum Envelope of Waters" (MOM) image was generated for high tide, and thus shows the worst-case inundation scenarios for a mid-strength Category 2 hurricane moving WNW at 5 mph. For more information on storm surge, consult our detailed storm surge pages.

Track forecast for Alex
The latest 12 UTC (7am CDT) runs of our most reliable computer models confirm the faster movement of Alex to the coast, and residents in the affected areas now have 12 hours less to prepare for Alex's arrival than it seemed with yesterday's forecasts. Conditions will begin to deteriorate along the coast late tonight, so today is the day to finish preparations if you live near the Texas/Mexico border! The ridge that is steering Alex to the northwest is expected to strengthen today and Wednesday, which should push Alex on a more west-northwest and then westerly track on Wednesday. A few models even have Alex moving west-southwest by the time it makes landfall. The most northerly landfall location, near Brownsville, is predicted by the HWRF model.

To get the probability of receiving tropical storm force winds or hurricane force winds for your location, I recommend the NHC wind probability forecasts. The 4am CDT (9 UTC) wind probability product predicted that Brownsville, Texas had the highest odds of getting a direct hit from Alex:

Brownsville, TX: 88% chance of tropical storm conditions (winds 39+ mph), 23% chance of hurricane force winds (74+ mph). This is the cumulative probability through Saturday morning. The wind probability forecasts also include separate probabilities for each 12-hour period between now and three days from now, and each 24 hours for the period 4 - 5 days from now.

Corpus Christi, TX: 42% tropical storm, 1% hurricane.

La Pesco, MX: 37% tropical storm, 3% hurricane.

Freeport, TX: 18% tropical storm, 0% hurricane.

Tampico, MX: 14% tropical storm, 0% hurricane.

Galveston, TX: 13% tropical storm, 0% hurricane.

Intensity forecast for Alex
Alex is over a region of ocean with a warm, clockwise rotating Loop Current eddy that broke off from the Loop Current in July 2009 and moved west-southwest over the past 11 months. This eddy has moderately high total ocean heat content . Wind shear has fallen to a low 5 knots, and is projected by the SHIPS model to remain in the low range, below 10 knots, this afternoon and Wednesday. The combination of low wind shear and moderately high ocean heat content should allow Alex to intensify into a Category 1 hurricane, but time is running out for it to be a Category 2 hurricane. NHC is giving Alex a 79% chance of being a hurricane on Wednesday morning, and a 4% chance it will be a major hurricane at that time. Water vapor satellite images show the amount of dry air over the western Gulf of Mexico has decreased over the past day, though as I noted above, the dry slot wrapping into Alex's core is currently keeping the storm from closing off an eyewall. Dry air may turn out to be an increasing detriment to Alex on Wednesday as the storm approaches land. Another factor limiting Alex's intensification may be that the atmosphere is more stable than usual right now--temperatures at 200 mb are a rather warm -50°C, and are expected to warm an additional 1 - 2 degrees by Wednesday. I don't expect Alex to stall out again, so slow motion leading to upwelling of cold water will probably not be a problem for Alex. The main issue limiting intensification will be the fact that Alex is so large, and it takes more time for a large storm to organize. Thus, I think Alex has only a 10% chance of intensifying into a major hurricane before landfall.

Elsewhere in the tropics
The last few runs of the NOGAPS model have been predicting the formation of a tropical disturbance off the coast of Nicaragua on Friday or Saturday that will move northwestward towards western Cuba. The GFS model, and the two models that use it for starting conditions, the GFDL and HWRF, are indicating the possibility that a weak extratropical storm may form along coastal Alabama this weekend. It is unlikely that such a storm would be over water long enough to transition to a tropical storm.

Wind and ocean current forecast for the BP oil disaster
It currently appears that Alex's winds will not directly affect the oil slick location. However, because Alex is such a deep low pressure region, strong southeast to south winds of 10 - 20 knots will blow over the oil slick region today through Thursday, according to the latest marine forecast from NOAA. The resulting currents should act to push oil to the west and northwest onto portions of the Louisiana, Mississippi, and Alabama coasts, according to the latest trajectory forecasts from NOAA and the State of Louisiana. Oil will also move westward along the central Louisiana coast towards the Texas border. Alex is currently bringing swells of 3 - 4 feet to the coastal regions impacted by the oil slick, and these swells will increase to 6 - 8 feet on Wednesday. Wave heights will increase to 5 - 7 feet on Wednesday. Alex is expected to bring a storm surge of 1 - 2 feet along the coast in the oil spill region. The swells and waves that will accompany these high water levels will act to push oil deep into the marshlands in some locations. The long range forecast for the oil slick region is uncertain, due to the possibility a weak area of low pressure might develop late this week along the remains of a cold front draped across the region.

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

"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) Alex
2) A look ahead at what may happen the rest of hurricane season

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.

Next post
I'll have an update Wednesday morning by 9:30am CDT. Rob Carver is planning on doing a late-night update tonight.

Jeff Masters

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1193. Patrap
Suggested reading.

Conservation of Momentum and energy.

Angular Momentum

Quiz Weds at 00 UTC
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If Alex catches up to its pressure, it would become a major hurricane.

Its running out of time though...
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IMO we'll find hurricane force winds south of the COC. That's were the heaviest convection is.
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WTF, man... 974 mb. Would be very interesting if this was still a TS after all this!!! Probably be the deepest on record for a TS. Also looking at RGB loop, almost appears to be a SW jog. Bear in mind, earlier this afternoon the models were projecting a SW turn (after landfall though). Interesting stuff here.
Member Since: March 19, 2010 Posts: 0 Comments: 1147
Call me a dunce and slap me silly if Alex isn't a hurricane by late tonight.
Member Since: August 9, 2009 Posts: 10 Comments: 4979
Quoting Stormchaser2007:
Alex is probably the strongest TS in history if that reading is right.



I said it first lol
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1186. Patrap
I gotta get a Loudspeaker..

LOL
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Quoting Chicklit:

'It ain't the meat it's the motion.'
Alex has not been able to tighten up its circulation.

LMAO!!!
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Quoting CybrTeddy:
If Alex gets below 970 mb and its still a Tropical Storm.. that would be utterly insane. Category 3 pressure in a TS.


that would be crazy... maybe like taz says it would be changed post season lol
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Quoting Stormchaser2007:
Alex is probably the strongest TS in history if that reading is right.

Yup, that is definitely not suspicious because of the steady decrease, plus I'm sure that's not the lowest pressure.
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Quoting Stormchaser2007:
Alex is probably the strongest TS in history if that reading is right.





yup i was thinking the same thing
Member Since: May 21, 2006 Posts: 5091 Comments: 115082
Alex is probably the strongest TS in history if that reading is right.

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If Alex gets below 970 mb and its still a Tropical Storm.. that would be utterly insane. Category 3 pressure in a TS.
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1178. pilatus
omg. 974.0 and still a little off the eye. rapid intensification?
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1177. Patrap
NOAA ADDS GOM Viz Loop

Rapid scan
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Quoting jaevortex:


christ how far out? 40 miles?
Like 10 miles. These are the 8PM coordinates: 23.2°N 94.5°W
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Quoting Patrap:
Size matters..Size matters..Size matters

Did I mention Cyclone size matters?

'It ain't the meat it's the motion.'
Alex has not been able to tighten up its circulation.
Member Since: July 11, 2006 Posts: 14 Comments: 11322
Quoting CybrTeddy:
974.0 mb found by recon..

.. okay this is a Hurricane.


Or the strongest Tropical Storm in history.
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i think they still say 70mph winds next update
Member Since: May 21, 2006 Posts: 5091 Comments: 115082
1171. JLPR2
9740
O_O
:\
:O
Starts to hyperventilate
*dies*
XD
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Alex is probably down to 970mbs.
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All right what's to keep this from doing a loop d loop down their?
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I was thinking sub-975mb before, I think we might see sub-970mb now.
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OMFG
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974.0 mb found by recon..

.. okay this is a Hurricane.
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Damn.

974mb.

Not seeing any strong winds.
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Quoting MiamiHurricanes09:
974.0MB and not at the center yet!!

000
URNT15 KNHC 300016
AF303 1001A ALEX HDOB 16 20100630
000700 2321N 09448W 8430 01411 9900 +200 +157 052043 043 037 000 00
000730 2320N 09448W 8432 01406 9897 +200 +154 049042 043 037 000 03
000800 2319N 09446W 8430 01404 9894 +197 +152 048042 043 037 000 00
000830 2317N 09445W 8432 01399 9889 +197 +155 048041 041 036 000 03
000900 2316N 09444W 8432 01395 9886 +197 +160 049041 043 037 000 00
000930 2315N 09443W 8429 01394 9881 +196 +164 048041 042 037 000 00
001000 2314N 09442W 8429 01391 9876 +200 +161 049041 042 038 000 03
001030 2312N 09440W 8431 01384 9871 +201 +154 048043 043 038 000 00
001100 2311N 09439W 8427 01382 9864 +199 +162 048042 044 038 001 00
001130 2310N 09438W 8432 01371 9860 +198 +159 045044 044 037 000 00
001200 2309N 09437W 8430 01367 9855 +193 +160 042044 045 038 003 00
001230 2307N 09436W 8429 01364 9848 +193 +161 042043 045 040 006 00
001300 2306N 09435W 8429 01355 9840 +191 +165 040043 043 045 010 00
001330 2305N 09433W 8428 01348 9831 +193 +166 038044 045 045 010 00
001400 2304N 09432W 8423 01343 9816 +206 +154 036046 047 041 004 00
001430 2302N 09431W 8429 01330 9804 +207 +151 032048 049 044 002 00
001500 2301N 09430W 8428 01312 9786 +207 +159 024051 052 045 005 00
001530 2300N 09428W 8435 01291 9771 +203 +169 018044 047 047 005 03
001600 2259N 09427W 8426 01283 9753 +202 +170 014033 039 042 005 00
001630 2258N 09425W 8436 01261 9740 +207 +167 008020 025 030 002 03
$$
;




christ how far out? 40 miles?
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Alex is such a legand, I think NHC kinda of scared they might cause panic. I feel Alex might be a cane.
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OMG
Member Since: May 21, 2006 Posts: 5091 Comments: 115082
1161. Patrap
Size is ALEX's most burdensome Load
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974.0MB and not at the center yet!!

000
URNT15 KNHC 300016
AF303 1001A ALEX HDOB 16 20100630
000700 2321N 09448W 8430 01411 9900 +200 +157 052043 043 037 000 00
000730 2320N 09448W 8432 01406 9897 +200 +154 049042 043 037 000 03
000800 2319N 09446W 8430 01404 9894 +197 +152 048042 043 037 000 00
000830 2317N 09445W 8432 01399 9889 +197 +155 048041 041 036 000 03
000900 2316N 09444W 8432 01395 9886 +197 +160 049041 043 037 000 00
000930 2315N 09443W 8429 01394 9881 +196 +164 048041 042 037 000 00
001000 2314N 09442W 8429 01391 9876 +200 +161 049041 042 038 000 03
001030 2312N 09440W 8431 01384 9871 +201 +154 048043 043 038 000 00
001100 2311N 09439W 8427 01382 9864 +199 +162 048042 044 038 001 00
001130 2310N 09438W 8432 01371 9860 +198 +159 045044 044 037 000 00
001200 2309N 09437W 8430 01367 9855 +193 +160 042044 045 038 003 00
001230 2307N 09436W 8429 01364 9848 +193 +161 042043 045 040 006 00
001300 2306N 09435W 8429 01355 9840 +191 +165 040043 043 045 010 00
001330 2305N 09433W 8428 01348 9831 +193 +166 038044 045 045 010 00
001400 2304N 09432W 8423 01343 9816 +206 +154 036046 047 041 004 00
001430 2302N 09431W 8429 01330 9804 +207 +151 032048 049 044 002 00
001500 2301N 09430W 8428 01312 9786 +207 +159 024051 052 045 005 00
001530 2300N 09428W 8435 01291 9771 +203 +169 018044 047 047 005 03
001600 2259N 09427W 8426 01283 9753 +202 +170 014033 039 042 005 00
001630 2258N 09425W 8436 01261 9740 +207 +167 008020 025 030 002 03
$$
;


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1159. Patrap
A good Comparison in relative terms

69, Camille a Cat 5 at Landfall...24 ft Storm Surge.

One could drive thru the impact Zone in a Hour.

East to West



K in 2005 Cat 3/4 at Landfall.. 30 foot storm Surge.

Took 3 Hours to drive from Impact zone end to end.

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And the cloud tops warmed further near center. Wonder IF they are going to find more than 70 mph.

So what's holding it back. Anyone?



Still susceptible to d-min? Maybe?
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting MiamiHurricanes09:
What's the link? I lost it, again. Lol.


Linky
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Quoting jaevortex:


8:30
What's the link? I lost it, again. Lol.
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Quoting lopaka001:
I am convince that Barometer Bob is Mr. Rogers..
StormW when do you come on?


8:30
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1154. Patrap
Size matters..Size matters..Size matters

Did I mention Cyclone size matters?
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1153. Patrap

ALEX Graphics Archive


3-Day Track Forecast, Uncertainty Cone, and Watch/Warning

3-Day Cone and Watch/Warning (no track line)

5-Day Track Forecast, Uncertainty Cone, and Watch/Warning

5-Day Cone and Watch/Warning (no track line)

Surface Wind Field and Watch/Warning

Wind History

Maximum 1-minute Wind Speed Forecast Table

34-kt Surface Wind Speed Probabilities (120 Hours)

50-kt Surface Wind Speed Probabilities (120 Hours)

64-kt Surface Wind Speed Probabilities (120 Hours)
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Quoting pipelines:


They haven't upgraded alex to hurricane status because it hasn't been a hurricane. Pressure doesn't dictate designation, wind speed does. The NHC will upgrade Alex to hurricane status when they have proof it is a hurricane, not a second before.

I understand , but when they quote(list) the most intense hurricanes , they are always graded by pressure not necessarily wind speed, personally I agree with windspeed also, this is what I find confusing when rating the intensity of a hurricane, for example Gilbert had a lower pressure than Ivan, crossed nearly the same distance from us (Grand Cayman) on a similar path, yet Ivan devastated us and to me Gilbert was nothing short of a good summer squall compared to Ivan, though I'll admit Gilbert was a quick mover but still Gilberts power or wind was no comparison to Ivan's.
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Quoting JLPR2:


O_O
If thats far from the center I dont want to know the central pressure XD
Lol. I believe it is about 40 miles from the center.
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may be they will find a 875mb
Member Since: May 21, 2006 Posts: 5091 Comments: 115082
1149. Patrap
00:06:30Z 23.383N 94.817W 842.9 mb

(~ 24.89 inHg) 1,414 meters

(~ 4,639 feet) 990.4 mb

(~ 29.25 inHg) - From 53° at 42 knots
(From the NE at ~ 48.3 mph)
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990mb 40 miles away from the center.

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1147. JLPR2
Quoting MiamiHurricanes09:
Still far from the center. Lowest pressure 990.4mb.

000
URNT15 KNHC 300006
AF303 1001A ALEX HDOB 15 20100629
235700 2351N 09505W 8429 01453 9952 +190 +147 062041 041 035 000 00
235730 2349N 09504W 8428 01452 9951 +189 +146 061041 042 034 000 00
235800 2347N 09504W 8432 01446 9948 +191 +146 061042 042 035 000 03
235830 2346N 09503W 8429 01449 9947 +189 +151 059040 041 036 000 00
235900 2344N 09503W 8429 01445 9946 +187 +156 064042 043 037 000 00
235930 2343N 09502W 8431 01442 9942 +190 +155 063041 041 037 000 00
000000 2341N 09501W 8430 01442 9939 +191 +154 061041 042 038 000 03
000030 2339N 09501W 8427 01444 9937 +190 +157 059039 039 037 001 03
000100 2338N 09500W 8430 01437 9936 +190 +158 059040 040 037 001 00
000130 2337N 09459W 8434 01431 9934 +190 +157 062040 040 038 000 00
000200 2335N 09458W 8426 01437 9930 +190 +159 058040 041 038 000 00
000230 2334N 09457W 8430 01431 9929 +190 +158 056039 040 039 000 00
000300 2333N 09456W 8430 01429 9926 +190 +159 056040 041 038 000 03
000330 2331N 09455W 8429 01430 9922 +192 +159 054040 041 038 000 03
000400 2330N 09454W 8429 01426 9920 +194 +159 054039 040 038 001 00
000430 2328N 09453W 8432 01421 9917 +194 +159 055039 040 038 000 00
000500 2327N 09452W 8429 01421 9916 +190 +161 054040 041 039 003 00
000530 2326N 09451W 8426 01422 9912 +192 +161 053040 042 039 002 00
000600 2324N 09450W 8433 01413 9908 +194 +159 053039 040 038 000 00
000630 2323N 09449W 8429 01414 9904 +197 +155 053042 042 037 000 00
$$
;



O_O
If thats far from the center I dont want to know the central pressure XD
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1145. will45
Quoting Tazmanian:




they this found a 904mb >??????


990.4
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Quoting Stormchaser2007:


lol

Sorry.
Lol.
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oh
Member Since: May 21, 2006 Posts: 5091 Comments: 115082

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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.