Irene continues to weaken

By: Dr. Jeff Masters , 8:46 PM GMT on August 26, 2011

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Satellite data and measurements from the Hurricane Hunters show that Irene continues to weaken. A 1:32 pm EDT center fix by an Air Force Reserve aircraft found that Irene's eyewall is still gone, and the central pressure had risen to 951 mb from a low of 942 mb this morning. The winds measured in Irene near the surface support classifying it as a strong Category 1 hurricane or weak Category 2. Satellite imagery shows a distinctly lopsided appearance to Irene's cloud pattern, with not much heavy thunderstorm activity on the southwest side. This is due to moderate southwesterly wind shear of 10 - 20 knots. This shear is disrupting Irene's circulation and has cut off upper-level outflow along the south side of the hurricane. No eye is visible in satellite loops, but the storm's size is certainly impressive. Long range radar out of Wilmington, North Carolina, shows that the outermost spiral bands from Irene have moved ashore over North Carolina. Winds at buoy 41004 100 miles offshore from Charleston, SC increased to 47 mph, gusting to 60 mph at 3 pm EDT, with significant wave heights of 25 feet.


Figure 1. MODIS satellite image of Hurricane Irene taken at 11:50 am EDT Friday August 26, when Irene was a Category 2 hurricane with 105 mph winds. The eyewall collapsed several hours before this image was taken, and no eye is apparent. Image credit: a href=http://rapidfire.sci.gsfc.nasa.gov/gallery/ NASA.


Figure 2. Distribution of Irene's wind field at 3:30 pm EDT Friday August 26, 2011, as observed by the Hurricane Hunters and buoys. The right front quadrant of the hurricane had about 90% of the storm's hurricane-force winds (yellow and warmer colors, bounded by the heavy black line between the "50" and "60" knot thin black lines.) Tropical storm-force winds (heavy black like bounding the light blue area) extended out 290 miles from the center of Irene. Image credit: NOAA/AOML/HRD.

Forecast for Irene
With its eyewall collapsed and just 18 more hours over water before landfall, Irene does not have time to build a new eyewall and intensify. The storm is too large to weaken quickly, and the best forecast is that Irene will be a strong Category 1 hurricane at landfall in North Carolina on Saturday. Based on the latest wind analysis from NOAA's Hurricane Research Division (Figure 2) and Irene's continued weakening trend, I predict that the 80-mile section of North Carolina coast to the right of where Irene makes landfall will receive sustained hurricane-force winds of 75 - 85 mph on Saturday at landfall; the 80-mile section of coast to the left will receive 55 - 75 mph winds. High wind shear of 30 knots will begin ripping into Irene Sunday morning when it is near Southern New Jersey, and more rapid weakening will occur. By the time Irene arrives on Long Island Sunday afternoon, it will probably have top sustained winds in the 65 - 75 mph range. However, since Irene is such a huge storm--tropical storm force winds extend out up to 290 miles from the center--it has set a massive amount of the ocean's surface in motion, which will cause a much larger storm surge than the winds would suggest. At 3:30 pm EDT this afternoon, a wind analysis from NOAA/HRD (Figure 2) indicated that the potential storm surge damage from Irene still rated a 5.0 on a scale of 0 to 6. This is equivalent to the storm surge a typical Category 4 hurricane would have. While this damage potential should steadily decline as Irene moves northwards and weakens, we can still expect a storm surge one full Saffir-Simpson Category higher than Irene's winds when it impacts the coast. Since tides are at their highest levels of the month this weekend due to the new moon, storm surge flooding will be at a maximum during the high tidal cycles that will occur at 8 pm Saturday night and 8 am Sunday morning. Wherever Irene happens to be at those times, the storm surge damage potential will be maximized. I continue to give a 20% chance that a 3 - 4 foot storm surge high enough to over-top the Manhattan flood walls and swamp the New York City subway system will occur on Sunday. The latest 11 am probabilistic storm surge map from NHC shows a 20 - 30% chance of a storm surge in excess of 3 feet in New York Harbor (Figure 4.) Keep in mind that these maps are calculated for normal tide level, and this weekend's high tides will be nearly 1 foot above normal.

Insurance company AIR-Worldwide is estimating that insured damages from Irene in the U.S. will be $1.5 - $6 billion. They estimate losses in the Caribbean at $0.5 - $1.1 billion from Irene.


Figure 3. Storm surge heights, in feet above normal tide level, which have a 20 percent chance of being exceeded during the next 3 days.  The graphic is based upon an ensemble of Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model runs using the current National Hurricane Center (NHC) official hurricane advisory. The exceedance heights depend on the historical accuracy of NHCs forecasts of hurricane track, and wind speed, and an estimate of storm size. Image credit: NOAA.


Figure 4. Overall chance that storm surges will be greater than 3 feet above normal tide levels during the next 3 days.  The graphic is based upon an ensemble of Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model runs using the current National Hurricane Center (NHC) official hurricane advisory.  Storm surge probabilities depend on the historical accuracy of NHCs forecasts of hurricane track, and wind speed, and an estimate of storm size. Image credit: NOAA.

Links
For those of you wanting to know your odds of receiving hurricane force or tropical storm force winds, I recommend the NHC wind probability product.

Wunderground has detailed storm surge maps for the U.S. coast.

The National Hurricane Center's Interactive Storm Surge RIsk Map, which allows one to pick a particular Category hurricane and zoom in, is a good source of storm surge risk information.

Wunderblogger Mike Theiss is in Nassau, documenting the storm's impact on the Bahamas.

Internet radio show on Irene at 4:30pm EDT
Wunderground meteorologists will be discussing Hurricane Irene on a special edition of our Internet radio show, the Daily Downpour, today (Friday) at 4:30pm EDT. Shaun Tanner , Tim Roche, Angela Fritz, and Rob Carver will take your questions. The email address to ask questions is broadcast@wunderground.com.

Jeff Masters

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Quoting Joshfsu123:



In the NHC discussion, they state extra ridging in the next 12-24 hours will keep Irene along the coastline - so if this verifies, you should see Irene bend a little more to the left once around the OBX area - this will keep it riding the coastline from Maryland/Delaware, to New Jersey and then New York.

Radar suggests she is on path to landfall in the OBX.


Not doubting the track at all, canes wobble. Close to land like this however, that jog NE just spared 25 miles of people from experiencing hurricane winds.
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At 39 hours, the GFS has a powerful Irene directly over NYC.

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1748. Levi32
Quoting GatorWX:
Does anyone think the gfdl scenario is plausible to some extent? Initially, it's off quite a bit showing Irene moving north from the beginning of the run, and I expect more of a ne heading as the storm moves through the mid atlantic into ne, but overall, the model is hinting at the storm bending back to the left as the current trough pulls out. I highly doubt she'll make landfall in NJ and move inland, but I am interested in how the model builds a bit of ridging after the current trough moves out. What I disagree with is the model not showing much, if any influence from the midwest trough approaching the storm, and I think if she does move in a more northerly direction, it would be brief because of the approaching trough.


Its 500mb forecast shows the reason to be a secondary shortwave that rounds the base of the trough after the first shortwave moves by to the north over southern Canada. The NAM shows this as well. It's possible that the hurricane could phase with this 2nd shortwave and pass up a bit farther west than forecast, more over Vermont. The GFDL is not as far outside of the model pack this time around, and thus may have a better chance of being right, but it has had an incorrect left bias so far.
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Quoting NoVaForecaster:
To all Fishcasters:



I think it's safe to say that dinner is served.
Better pull that. I got 24 hr in the WU Brig for similar.
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Quoting sunlinepr:


So there is still a posibility that it stays off land... Besides everything, good news...


In my opinion, no way it misses the Outer Banks and still a high probability of a second land fall in the New England States.
Member Since: August 29, 2010 Posts: 0 Comments: 5236
Glad it has weakened a bit. That being said, my coast has little or no dunes. The outer banks, va and md will take a big hit here. As to points north, be very glad this isn't as bad as it could be and you will take a lot of water up the nose. Catatrophic, no, but a lot of trouble coming. Just don't cut NC 12, please.
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Quoting scubanaked:
Please, Jeff Masters, update the message at the top of every page of your forum I'm still reading that you made a statement at 11:30 am. I read your message yesterday and I let all my coworkers know, and they alerted their people up north. Because of that some people in NY got a heads up. Thank you. But, now I am looking to you to issue a statement of your assessment, because it's very hard to discern who is actually qualified to speak on here
if residents of the Northeast don;t heed the advice/statements of their mayors/governors/emergency management as to the dangers and how to protect from them, what would make you think a blog would be of any help. Unfortunately, in this case, some people are going to learn from their own stupidity and mistakes.
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1743. j2008
Quoting ConnecticutWXGuy:


you are somewhat correct. I think people should have to take an IQ test and score at least 100 (average) to comment in here. Most of the bickerers and bashers seem like they would have trouble achieving the IQ of a fetus.
LOL. I'm a Freshman right now and I'm trying to learn about hurricanes etc. Its sorta an addiction, It shocks me how uneducated some of the people are on this blog. They seem to thing they are so importaint that they have to be heard, like that Jason dude who has 32 different names LOL. On the other hand I really feel for the people on the East coast, many of them dont know what its like to go through a hurricane. Everybody please be safe, Irene isnt a joke so I hope everybody is getting prepared.
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Quoting P451:


That's the forecast and there's little reason to doubt it.

I've been maintaining for days that the northern region needed to wait to see how the storm interacted with the outer banks.

Once there we would know whether or not this was going to beeline for western LI, pull a little east, or pull a little inland and decay some.

Despite the little pull to the NNE tonight I still say like you said and the forecast said it will bend back a little northward and ride up the coast and landfall in western LI around noon tomorrow or so.

Seems like the best bet, but, we will know for sure in the morning.

It's still a little tricky but at this point that only matters for the western most portions forecasted to feel the impacts of the storm. She's so big it's not going to change anyone's forecast much except for the western most sections.




Yep - I am in DC so we are under a Tropical Storm warning and expecting Tropical Storm conditions (30/40 mph with higher gusts) - but the Hurricane Warning is about 30 miles to our SE now... so any shift westward, ever so slightly, would put our region in worse conditions.

A shift eastward may keep us out of the rain shield that's currently over NC and about to enter SE Virginia...

So I'm eagerly waiting to see what things look like midday tomorrow.
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Quoting BaltimoreBrian:
I think the mandatory evacuations of hundreds of thousands of people in NJ and NY is overdoing it. I'm just not seeing such high surges as possible.

I think the real killer will be river flooding inland where people think they are safe.
I hope you are right about the surge but if you go to the site you posted, the real times observations at 8656483 Beaufort, NC are running above predicted and the trend doesn't look good to me. I would be very carefull what I predicted right now, or whom I listened too. Evac orders are to be respected unless you want to be Orca bait.
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Quoting PrivateIdaho:
Impressive rain sheild....tornado warnings popping up.




There have been 550 deaths from tornadoes in the USA this year. If we have three more this year will be in second place for tornado fatalities.
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Yep, me & you both!
Still trying to determine if friends left --- I am pretty sure they did since they have a brain and their home is beachfront.... But I hate to see the damage along the Outerbanks and all along the east coast. : (
Quoting zoomiami:


Yep -- it is a shame.

Watching on all these great places I've visited and lived up and down the coast, makes me sad.

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Quoting Joshfsu123:



If accurate, Levi has been stating some of those winds above the surface would like mix down to the surface upon landfall - means some could face 100/110+ winds at the surface, especially with wind gusts..


The frictional effects of those winds traveling over land will bring those 2,000-3,000 foot winds down to the surface. If you look at the readings from the SFMR instrument, portions of the coastline and those close to the shore can expect winds around 10-15% higher since they are going to be over land not over the ocean where there is little to no friction.
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Moving NNE,but from the NHC discussion i am still not energized.
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Quoting scubanaked:
Please, Jeff Masters, update the message at the top of every page of your forum I'm still reading that you made a statement at 11:30 am. I read your message yesterday and I let all my coworkers know, and they alerted their people up north. Because of that some people in NY got a heads up. Thank you. But, now I am looking to you to issue a statement of your assessment, because it's very hard to discern who is actually qualified to speak on here


Best i can tell you from who is on. Levi32, Progressivepulse and P451. No intent to offend others....Just saw reedzone, he is good also.
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Wilmington has been spared and I am safe. Wrightsville may have had worse impacts And I wish them good news tomorow but I'm shocked how weak Irene is here in wilmingon. I think the NE will be in for a big surprise they've evacuated for nothing. Just how I bought $150 of supplies for nothing.

Next time I'll trust my instincts and gut and live with what happens. I feel dumb and misled right now.

You have another ? hours before actually being hit.. Don't congradulate yourself yet
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Every time I look at the radar loops of Irene coming ashore, I think of Katrina. I just remember being terrified while watching the radar loops of her coming ashore...before we lost power of course. Just two monster hurricanes with massive amounts of rain and wind.

I live in Hattiesburg...winds well over 100mph here.

Katrina Radar Loop


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Quoting Levi32:
Wave heights at a buoy south of Wilmington, North Carolina:


Woot!
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ALL OF THE MODELS SUGGEST THAT SOME SLIGHT MID-LEVEL
RIDGING WILL OCCUR ACROSS SOUTHERN NEW ENGLAND AND THE MID-ATLANTIC STATES DURING THE NEXT 12-24 HOURS...WHICH SHOULD ACT TO KEEP IRENE CLOSE TO THE COASTS OF NEW JERSEY AND THE DELMARVA PENINSULA."


How close to Delmarva we talkin' here?
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Edited my comment and look what happens.

Out for the night, I hope, everyone stay safe.
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Impressive rain sheild....tornado warnings popping up.

Member Since: August 29, 2010 Posts: 0 Comments: 5236
Quoting zoomiami:


Yep -- it is a shame.

Watching all these great places I've visited and lived up and down the coast, makes me sad.

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1725. GatorWX
Does anyone think the gfdl scenario is plausible to some extent? Initially, it's off quite a bit showing Irene moving north from the beginning of the run, and I expect more of a ne heading as the storm moves through the mid atlantic into ne, but overall, the model is hinting at the storm bending back to the left as the current trough pulls out. I highly doubt she'll make landfall in NJ and move inland, but I am interested in how the model builds a bit of ridging after the current trough moves out. What I disagree with is the model not showing much, if any influence from the midwest trough approaching the storm, and I think if she does move in a more northerly direction, it would be brief because of the approaching trough.
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Quoting Beachfoxx:
{{{Zoo}}}

Its a shame that it takes a monster storm to bring so many of us out of the woodwork! : )
Hope all is well down your way...


Yep -- it is a shame.

Watching on all these great places I've visited and lived up and down the coast, makes me sad.

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Quoting BaltimoreBrian:
I think the mandatory evacuations of hundreds of thousands of people in NJ and NY is overdoing it. I'm just not seeing such high surges as possible.

I think the real killer will be river flooding inland where people think they are safe.
please go to Cape May and let me know what happens, if you survive, that is...
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Please, Jeff Masters, update the message at the top of every page of your forum I'm still reading that you made a statement at 11:30 am. I read your message yesterday and I let all my coworkers know, and they alerted their people up north. Because of that some people in NY got a heads up. Thank you. But, now I am looking to you to issue a statement of your assessment, because it's very hard to discern who is actually qualified to speak on here
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Quoting HurricaneHunterJoe:
excellent



If accurate, Levi has been stating some of those winds above the surface would like mix down to the surface upon landfall - means some could face 100/110+ winds at the surface, especially with wind gusts..
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1718. snotly
No it was a better blog 5.2345 years ago, exactly, on a Tuesday, I remember it better than everyone else.


Quoting OSMS:
This use to be a decent weather/storm blog 5 - 6 years ago. Now it seems to be about everybody trying to prove they are better than everyone else.
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1717. 900MB
For real, from NYC, good night. Need my rest, someone has to keep an eye on Cantore and Cooper!
Member Since: June 11, 2006 Posts: 0 Comments: 684
{{{Zoo}}}

Its a shame that it takes a monster storm to bring so many of us out of the woodwork! : )
Hope all is well down your way...
Quoting zoomiami:


lmao
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Quoting PrivateIdaho:


I had it hitting Moorehead City earlier but now it looks to be headed toward cape Hatteras.....looks like more than a jog to me.


So there is still a posibility that it stays off land... Besides everything, good news...
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Quoting aquak9:
hi foxx!!

Beell's gotta buzz?? well worth losing sleep over to watch this! :)

and to the "misled" person- save your hurricane supplies and donate them to a food pantry come thanksgiving.
or to the people to the east of you who will need it come Sunday and beyond...
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Quoting OSMS:
This use to be a decent weather/storm blog 5 - 6 years ago. Now it seems to be about everybody trying to prove they are better than everyone else.


you are somewhat correct. I think people should have to take an IQ test and score at least 100 (average) to comment in here. Most of the bickerers and bashers seem like they would have trouble achieving the IQ of a fetus.
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1711. zawxdsk
Whew - just got off the phone with the family in Wilmington. Apparently they were exaggerating when they said that they live 'right on the beach.' They live on the river side, which shouldn't be favorable for a storm surge. Still had power.

Still not the best of moves...
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1710. 900MB
Quoting Joshfsu123:


Negative on the path - NHC was quite clear in their discussion on what is likely to happen (this has outstanding model support as well) - Irene will make landfall in the OBX and then move near the coastline throughout the day tomorrow into Sunday.

From NHC discussion -

"THE FORECAST TRACK HAS ONLY BEEN NUDGED SLIGHTLY EASTWARD OF THE PREVIOUS TRACK THROUGH 36 HOURS DUE TO THE MORE EASTWARD INITIAL POSITION. HOWEVER...ALL OF THE MODELS SUGGEST THAT SOME SLIGHT MID-LEVEL
RIDGING WILL OCCUR ACROSS SOUTHERN NEW ENGLAND AND THE MID-ATLANTIC STATES DURING THE NEXT 12-24 HOURS...WHICH SHOULD ACT TO KEEP IRENE CLOSE TO THE COASTS OF NEW JERSEY AND THE DELMARVA PENINSULA."


Long Island is only 120 miles long, so we could both be right, besides, the "NHC Discussion" changes on a regular basis.
Member Since: June 11, 2006 Posts: 0 Comments: 684
Levi and Progressive thank you for the explanation. Makes sense for them not to fly at the surface. :) Sorry for the typos in the previous post, laying down and typing doesn't jive well with me. Levi, i know you are busy with Irene and many people look to your knowledge, so i will look for an update on the high once this system has moved on.

Many thanks to all on here who help the novices learn! Stay safe if you are in the storms path.
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1708. srada
Quoting CarolinaHurricanes87:


Ok I understand u some of u guys think preparing is the right thing and assure me doing it next time is the right thing to do thanks I appreciate the advice.

To the people taking personal shots... I could go for a jog right now if I didn't mind a light shower. Nothings happening. The beach is another story but 5 miles inland we r A okay. And as far as misled... A hurricane warning means hurricane conditions r expected. We have barely received tropical storm conditions and if u look at the radar we've received our heaviest part of the storm.


Carolina, I am from wilmington as well. Irene is not supposed to be here until 2am where we will feel hurricane force winds. You havent even begun to feel the wrath of Irene yet.
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Quoting atmosweather:
Now this is a little better...dropsonde ENE of the eye finds 90 mph surface winds and 120 mph winds at just below 3,000 feet.
excellent
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1706. OSMS
This use to be a decent weather/storm blog 5 - 6 years ago. Now it seems to be about everybody trying to prove they are better than everyone else.
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1705. Levi32
Wave heights at a buoy south of Wilmington, North Carolina:

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Quoting sunlinepr:


Is it moving now more to the east (NE)?


I had it hitting Moorehead City earlier but now it looks to be headed toward cape Hatteras.....looks like more than a jog to me.
Member Since: August 29, 2010 Posts: 0 Comments: 5236
Quoting 900MB:
Night everyone! NYC checking out.

I'm sure I will be on between 5 and 8 in the am. Parting thoughts:

-Will barely scrape outer banks and path will adjust to Eastern Long Island by 8 am.

-Next few hours will be interesting. If there is an intensity boost it is between now and 8 am.

-A boost before NC means a stronger storm for Long Island and Eastern NE. But, doubt intensity picks up more than a tick given the lousy presentation.

-Christie and Bloomberg will be more defensive than the Jets and the Giants come Monday night :)


Negative on the path - NHC was quite clear in their discussion on what is likely to happen (this has outstanding model support as well) - Irene will make landfall in the OBX and then move near the coastline throughout the day tomorrow into Sunday.

From NHC discussion -

"THE FORECAST TRACK HAS ONLY BEEN NUDGED SLIGHTLY EASTWARD OF THE PREVIOUS TRACK THROUGH 36 HOURS DUE TO THE MORE EASTWARD INITIAL POSITION. HOWEVER...ALL OF THE MODELS SUGGEST THAT SOME SLIGHT MID-LEVEL
RIDGING WILL OCCUR ACROSS SOUTHERN NEW ENGLAND AND THE MID-ATLANTIC STATES DURING THE NEXT 12-24 HOURS...WHICH SHOULD ACT TO KEEP IRENE CLOSE TO THE COASTS OF NEW JERSEY AND THE DELMARVA PENINSULA."
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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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