A Gulf of Mexico and an Eastern Atlantic Disturbance Worth Watching

By: Dr. Jeff Masters , 1:53 PM GMT on July 06, 2013

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A tropical disturbance (designated 94L by NHC on Friday) is over the Western Gulf of Mexico, and is headed north towards the Texas/Louisiana coast at 5 - 10 mph. Satellite loops show a modest area of disorganized heavy thunderstorm activity that has been steadily growing this morning. Wind shear has fallen to the moderate range, 10 - 20 knots, since Friday, and the lower wind shear is likely responsible for the increase in thunderstorm activity. A trough of low pressure over the Western Gulf of Mexico is pumping dry air into the west side of 94L, interfering with development. The disturbance should move inland by Sunday morning, bringing heavy rains of 1 - 3" along the Upper Texas and Western Louisiana coasts through Monday morning. None of the reliable forecast models predict that the disturbance will develop, and the disturbance has only a day over water with marginal conditions for development. In their 8 am EDT July 6 Tropical Weather Outlook, NHC gave the disturbance a 20% chance of developing into a tropical depression or tropical storm by Monday.


Figure 1. The Saturday morning NHC Tropical Weather Outlook shows two "Invests" worth watching: 94L over the Gulf of Mexico (area 1), and 95L over the Eastern Atlantic (area 2.) Both were given 20% chances of developing by Monday. Image credit: NHC.

Cape Verdes tropical wave 95L
As we approach mid-July, it's time to begin turning our attention to tropical waves coming off the coast of Africa. We have our first such system worthy of attention today, a tropical wave designated 95L over the Eastern Atlantic near 8°N 33°W, about 800 miles southwest of the Cape Verde Islands. Satellite loops show a modest area of heavy thunderstorms that is showing a moderate amount of spin. Wind shear is moderate, 10 - 20 knots, and ocean temperatures are warm, 28°C. The 8 am EDT Saturday forecast from the SHIPS model predicted that 95L would encounter cooler waters of 27.5°C over the weekend as it headed west to west-northwest at 15 - 20 mph. Wind shear is expected to remain moderate though Monday, which may allow for some additional organization. However, 95L is embedded in a very large area of dry air associated with the Saharan Air Layer (SAL), and July African waves typically have considerable trouble getting organized in the very dry air of the SAL. The disturbance could arrive in the Lesser Antilles Islands as early as Tuesday. A band a strong upper-level winds associated with the subtropical jet stream is expected to be over the northern islands at that time, and if 95L has penetrated as far north as 15°N latitude by that time, it will have to face very high wind shear of 30+ knots. But if 95L stays farther to the south, wind shear should be lower, giving the storm a better chance of development. None of the reliable forecast models predict that 95L will develop. In their 8 am EDT July 6 Tropical Weather Outlook, NHC gave the disturbance a 20% chance of developing into a tropical depression or tropical storm by Monday.


Figure 2. MODIS image of 95L taken at approximately 11 am EDT Saturday, July 6, 2013. Image credit: NASA.

Elsewhere in the tropics
A large upper-level cold-cored low pressure system a few hundred miles north of Puerto Rico will move west over the next dew days, arriving in the Bahamas by Sunday and South Florida by Tuesday. The models do not show that this low will will acquire a surface circulation, and there is only minimal heavy thunderstorm activity associated with it.

In the Eastern Pacific, Tropical Storm Erick is brushing the southwestern coast of Mexico, and is expected to intensify into a Category 1 hurricane on Saturday afternoon. Erick will bring heavy rains of 3 - 5 inches to Southwest Mexico, but the core of the storm is currently expected to remain just offshore. Erick will likely weaken to a tropical storm on Monday, when it will pass just south of Baja.

Cool San Francisco time-lapse fog video
Videographer Simon Christen has created a spectacular 4-minute time-lapse video of fog rushing in past the Golden Gate Bridge into San Francisco. He writes: ""Adrift" is a love letter to the fog of the San Francisco Bay Area. I chased it for over two years to capture the magical interaction between the soft mist, the ridges of the California coast and the iconic Golden Gate Bridge. This is where “Adrift” was born. The weather conditions have to be just right for the fog to glide over the hills and under the bridge. I developed a system for trying to guess when to make the drive out to shoot, which involved checking the weather forecast, satellite images and webcams multiple times a day. For about 2 years, if the weather looked promising, I would set my alarm to 5am, recheck the webcams, and then set off on the 45-minute drive to the Marin Headlands. I spent many mornings hiking in the dark to only find that the fog was too high, too low, or already gone by the time I got there. Luckily, once in a while the conditions would be perfect and I was able to capture something really special. Adrift is a collection of my favorite shots from these excursions into the ridges of the Marin Headlands."


Video 1. Adrift from Simon Christen on Vimeo.

Jeff Masters

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Quoting 1490. nigel20:

Emily (2005) was a small and very strong July hurricane. It's eye tracked well to our south here in Jamaica..luckily.

Hurricane Emily

Yeh well she did some bad stuff to us
Member Since: June 13, 2009 Posts: 2 Comments: 12150
Quoting 1499. huntsvle:


The BAM use a parameterization scheme that is characterized simply by the storms vertical stacking and upward voriticity maximum. It is designed to show what large synoptic features will guide the general motion of the storm while at different levels of the atmosphere. Weak storms tend to be driven by wind fields and synoptic features. The stronger and more vertically solid a storm is, the more it can overcome some of those features. Keep in mind, a TC tends to follow the path of least resistance.
So you're saying the deep storm feels a weakness in the Caribbean.
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Quoting 1497. unknowncomic:
Yep, just curious why a deep one takes the quick left turn.


The deep one isn't accurate to follow at this point, because it's assuming that the storm is very deep. You have to consider what the storms height was at initialization. BAM-D is making an inaccurate assumption at this point, and if a storm is a wave, then BAM-D will not initialize properly.
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Quoting 1484. wunderkidcayman:


Emily of 2005 and it did not recurve at all


I meant Isabel who recurved.

My point is I think '13 will be a hybrid of '04/05. There was a monster Bermuda High '04, and a lot of early CV storms below 10o ...contrasting '05, where the high was tame, but many early CVs. Just look at what's about to jump off Africa.. if 95L can get thus far intact, imagine what a wave who doesn't need the ITCZ can do.
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1500. Dakster
Quoting 1498. daddyjames:


Come on, 'fess up. You a closeted wishcaster. ;)


LOL. ;)
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Quoting 1485. unknowncomic:
Interesting how the BAM-D has it taking an abrupt SW turn. So a stronger storm feels the influence of what, a strong ridge?



The BAM use a parameterization scheme that is characterized simply by the storms vertical stacking and upward voriticity maximum. It is designed to show what large synoptic features will guide the general motion of the storm while at different levels of the atmosphere. Weak storms tend to be driven by wind fields and synoptic features. The stronger and more vertically solid a storm is, the more it can overcome some of those features. Keep in mind, a TC tends to follow the path of least resistance.
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Quoting 1495. Dakster:
What is the earliest a Major Hurricane has formed?

and what is the earliest a Cat 5 Hurricane has formed?

Just thinking out loud here. (Not that I think 95L will be either)


Come on, 'fess up. You a closeted wishcaster. ;)
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Quoting 1489. Dakster:


My understanding of the BAM suite is that they only take steering currents into account. The deeper the storm the higher up in the atmosphere the storm is. So the suite shows how the steering currents affect shallow, medium, and deep storms.
Yep, just curious why a deep one takes the quick left turn.
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Quoting 1481. wunderkidcayman:

Easy here I got two
Both had dry air and SAL to deal with plus both moving at same speed 17-20mph


Yes, but Ivan was already a tropical storm when it dropped south of 9N. It was already a closed circulation.

95L isn't. It most likely won't close its circulation off, if it doesn't do so in the next 12-24 hrs.
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1495. Dakster
What is the earliest a Major Hurricane has formed?

and what is the earliest a Cat 5 Hurricane has formed?

Just thinking out loud here. (Not that I think 95L will be either)
Member Since: March 10, 2006 Posts: 0 Comments: 10435
Quoting unknowncomic:
Interesting how the BAM-D has it taking an abrupt SW turn. So a stronger storm feels the influence of what, a strong ridge?



The BAMD has a problem,,, been doing that since the early model runs
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This setup, given the high to the north and its location would make Bertha Isabel and perhaps (1996) a GREAT analog. Hopefully that doesn't hold true for 95L though. We here in VA are weary after Sandy, Irene, Ernesto (06), Gaston, and Isabel.
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Quoting 1488. twistedfolks:
I'm sure in 2 days they will say 95l is hitting florida then in 4 days it wont be ( seen that story a millions times before )


LOL - yes, a big sigh of relief afterwards. I'm not saying that'll happen. Just saying that is what some of the models are saying.

Me, not sure. If it gets entangled in the mountains of Hispanola, I think it would have trouble doing anything at all.
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Quoting 1481. wunderkidcayman:

Easy here I got two
Both had dry air and SAL to deal with plus both moving at same speed 17-20mph
They were both spinning counter-clockwise as well. Ivan had a friendly environment from start to finish, save for a 6 hour gulp of dry air after it was already a formidable hurricane and before it became a monster.
.
Have you ever read the Tropical Cyclone Report on IVAN. Written by forcaster Stewart. Here. Link
.
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1490. nigel20
Quoting 1479. redwagon:


My favored analog for 95L is Emily 05. After that, Isabel, followed by Ernesto '12 - long CV tracker that replaced his coc about 8 times before landing in CentAm. Last year was the most multiple centers of circ I've ever seen, though '12 had a bunch.

This following the rule that CVs jumping off below 10o tend to run south their entire lives.

Emily (2005) was a small and very strong July hurricane. It's eye tracked well to our south here in Jamaica..luckily.

Hurricane Emily
Member Since: November 6, 2010 Posts: 11 Comments: 8139
1489. Dakster
Quoting 1485. unknowncomic:
Interesting how the BAM-D has it taking an abrupt SW turn. So a stronger storm feels the influence of what, a strong ridge?



My understanding of the BAM suite is that they only take steering currents into account. The deeper the storm the higher up in the atmosphere the storm is. So the suite shows how the steering currents affect shallow, medium, and deep storms.
Member Since: March 10, 2006 Posts: 0 Comments: 10435
Quoting 1485. unknowncomic:
Interesting how the BAM-D has it taking an abrupt SW turn. So a stronger storm feels the influence of what, a strong ridge?



Yes the one that's there now
Member Since: June 13, 2009 Posts: 2 Comments: 12150
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Interesting how the BAM-D has it taking an abrupt SW turn. So a stronger storm feels the influence of what, a strong ridge?

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Quoting 1480. redwagon:
Excepting Emily, who ran recurve.


Emily of 2005 and it did not recurve at all
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1483. Dakster
Quoting 1467. TropicalAnalystwx13:
Check out the tropical wave over central Africa (I call dibs, saw it first):



Grothar called that yesterday... You are very late.
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Quoting 1476. stormchaser19:
95L has improved his vorticity in the last 6 hours!!!!



Yep

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Quoting 1466. sar2401:


Ivan was a CV storm, not an ITCZ wave. Ivan was a very large wave that came off Africa on August 30. Ivan became a TD on September 2, a TS on September 3, and a Hurricane on September 5, the fourth major of 2004. The furthest south that Ivan got was 10N, still very far south, but she was a hurricane by then, not a wimpy tropical wave. Ivan became a cat 5 at 13.4N and remained a cat 5 for almost 9 days. Ivan at its peak was nearly the size of Texas, and was creating his own atmosphere as he plowed through the Caribbean, into the Gulf, up through Alabama, then all the way to Maryland, emerging back over the Atlantic, circling south, crossing Florida, getting back out into the Gulf, and then making final landfall in Lousiana. Ivan was a TS or above for 22 days.

I challenge you to find one thing about 95L which is similar to Ivan except they both happened to be further south than normal at one time.

Easy here I got two
Both had dry air and SAL to deal with plus both moving at same speed 17-20mph
Member Since: June 13, 2009 Posts: 2 Comments: 12150
Excepting Emily, who ran recurve.
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Quoting 1466. sar2401:


Ivan was a CV storm, not an ITCZ wave. Ivan was a very large wave that came off Africa on August 30. Ivan became a TD on September 2, a TS on September 3, and a Hurricane on September 5, the fourth major of 2004. The furthest south that Ivan got was 10N, still very far south, but she was a hurricane by then, not a wimpy tropical wave. Ivan became a cat 5 at 13.4N and remained a cat 5 for almost 9 days. Ivan at its peak was nearly the size of Texas, and was creating his own atmosphere as he plowed through the Caribbean, into the Gulf, up through Alabama, then all the way to Maryland, emerging back over the Atlantic, circling south, crossing Florida, getting back out into the Gulf, and then making final landfall in Lousiana. Ivan was a TS or above for 22 days.

I challenge you to find one thing about 95L which is similar to Ivan except they both happened to be further south than normal at one time.


My favored analog for 95L is Emily 05. After that, Isabel, followed by Ernesto '12 - long CV tracker that replaced his coc about 8 times before landing in CentAm. Last year was the most multiple centers of circ I've ever seen, though '12 had a bunch.

This following the rule that CVs jumping off below 10o tend to run south their entire lives.
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1478. nigel20
Quoting 1474. sar2401:

Possibly because they used the evacuation slides and were burned, suffering from smoke inhalation, or had fatal injuries from using the slides, which has happened before. From the pictures I saw, the rear pressure bulkhead was still intact when the hull was off the runway, so I really doubt they were thrown from the aircraft, I would expect a much higher death toll if that occured. As usual, there will be all kinds of reports after an aircraft accident that later turn out to be false.

It's pretty sad that there had to be fatalities. :(

We had an incident (December 2009) at the Norman Manley International Airport in Kingston, Jamaica where an American Airlines Boeing 737-800 overshot the runway (8900ft). There were only minor injuries, but it could've been worst as it crash landed only a couple feet from the Caribbean sea.


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Quoting 1474. sar2401:

Possibly because they used the evacuation slides and were burned, suffering from smoke inhalation, or had fatal injuries from using the slides, which has happened before. From the pictures I saw, the rear pressure bulkhead was still intact when the hull was off the runway, so I really doubt they were thrown from the aircraft, I would expect a much higher death toll if that occured. As usual, there will be all kinds of reports after an aircraft accident that later turn out to be false.


Agree with you - but a witness also is reporting that "When they did, they saw some people climbing out of San Francisco Bay around the airport, Hayes-White said."

From CNN also.

Edit: From NBC, " first-responders who arrived at the jet saw a handful of survivors emerging from the bay."
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95L has improved his vorticity in the last 6 hours!!!!


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1475. nigel20
Quoting 1472. ncstorm:


I believe Grothar beat you to it..

Good night Everyone!!

Night ncstorm!
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1474. sar2401
Quoting nigel20:
This from CNN Breaking News

‏@cnnbrk
SF fire chief on 2 who died in crash: "My understanding is that they were found on the runway."

Possibly because they used the evacuation slides and were burned, suffering from smoke inhalation, or had fatal injuries from using the slides, which has happened before. From the pictures I saw, the rear pressure bulkhead was still intact when the hull was off the runway, so I really doubt they were thrown from the aircraft, I would expect a much higher death toll if that occured. As usual, there will be all kinds of reports after an aircraft accident that later turn out to be false.
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Quoting 1471. gator23:
Why would you compare 95L to a gulf system at this point? It may not enter the Gulf. Nothing says it cant hit N. or S. Carolina or Florida etc...



Some models are bringing 95L into the SE gulf, then lifted north be a trough that develops. Somewhere in the vicinity of the Gulf Coast of FL.
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1472. ncstorm
Quoting 1467. TropicalAnalystwx13:
Check out the tropical wave over central Africa (I call dibs, saw it first):



I believe Grothar beat you to it..

Good night Everyone!!
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1471. gator23
Why would you compare 95L to a gulf system at this point? It may not enter the Gulf. Nothing says it cant hit N. or S. Carolina or Florida etc...

Quoting 1423. KoritheMan:
It should be noted that there is some historical precedent for strong July Gulf of Mexico hurricanes. I can actually think of three within the last ten years; Dolly in 2008, Dennis in 2005, and Claudette in 2003.

They typically aren't the big monstrous systems we're used to seeing during peak season (with the exception of Dennis), but upper end Category 1's to low end Category 2 hurricanes are not obscenely rare if conditions are right.

Not that that says anything about 95L's potential future.
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Quoting 1465. Tropicsweatherpr:


Hi nigel. Look at that very large complex in Central Africa. The train is leaving the station early.

Aww man.
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Quoting 1467. TropicalAnalystwx13:
Check out the tropical wave over central Africa (I call dibs, saw it first):

I think that's the wave the GFS really wants to develop.
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1468. nigel20
Quoting 1465. Tropicsweatherpr:


Look at that very large complex in Central Africa. The train is leaving the station early.

Yes indeed! Tropical activity should pick up significantly in another month or so.
Member Since: November 6, 2010 Posts: 11 Comments: 8139
Check out the tropical wave over central Africa (I call dibs, saw it first):

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1466. sar2401
Quoting wunderkidcayman:

It does not matter unless if condition are completely different when their not it almost the same Ivan had the same problems as 95L is having now it was moving fast as 95L and it had dry air and SAL problem as 95L does and both looked almost the same at the start


Ivan was a CV storm, not an ITCZ wave. Ivan was a very large wave that came off Africa on August 30. Ivan became a TD on September 2, a TS on September 3, and a Hurricane on September 5, the fourth major of 2004. The furthest south that Ivan got was 10N, still very far south, but she was a hurricane by then, not a wimpy tropical wave. Ivan became a cat 5 at 13.4N and remained a cat 5 for almost 9 days. Ivan at its peak was nearly the size of Texas, and was creating his own atmosphere as he plowed through the Caribbean, into the Gulf, up through Alabama, then all the way to Maryland, emerging back over the Atlantic, circling south, crossing Florida, getting back out into the Gulf, and then making final landfall in Lousiana. Ivan was a TS or above for 22 days.

I challenge you to find one thing about 95L which is similar to Ivan except they both happened to be further south than normal at one time.
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Quoting 1460. nigel20:


Hi nigel. Look at that very large complex in Central Africa. The train is leaving the station early.
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1464. nigel20
This from CNN Breaking News

‏@cnnbrk
SF fire chief on 2 who died in crash: "My understanding is that they were found on the runway."
Member Since: November 6, 2010 Posts: 11 Comments: 8139
Quoting 1418. beell:


I guess they did change the OP. But not by much.

NHOP 2013

5.5.1.3.1
Up to four 6-hourly fixes per day when a storm is within 500 nm of landfall and west of 52.5°W in the Atlantic.


Thanks, Beell, for clearing that up. Should have known there was a hard-n-fast rule being it's a military flight. Never really thought about it much, just knew it has been kind of understood for years that no flights were scheduled until a system had passed 55w. So, it's actually 52.5w. Good to know! :)
Member Since: July 9, 2006 Posts: 184 Comments: 29610
Quoting 1449. Levi32:


I try my best to communicate relevant information to countries near a storm, but I will pay extra attention to make sure I'm not leaving anything out for the Caribbean.


thanks man stay cool
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1461. gator23
The same can be said for Katrina, Andrew and now Sandy. People overreact. Those storms are the exception and not the rule.

Quoting 1454. CosmicEvents:
Agreed but good luck. Ever since IVAN every Cape Verde L and numerous waves that's come down the pike or anywhere near the same pike has been touted as IVAN part 2.
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1460. nigel20
Member Since: November 6, 2010 Posts: 11 Comments: 8139
Chantel and Dorian?.Could we be tracking two named storms by weeks end?
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Quoting 1455. Dakster:



No problem. Glad you took it constructively. ;)


I did and having a Blonde Moment :o)

Taco :o)
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1456. SLU
Quoting 1436. Tropicsweatherpr:


Maybe TSR saw that and went down in numbers. But Phil Klotzbach talked about the cooler sst in MDR too. Here it is below.


If a cool pool of water northwest of Africa filters into the main tropical development region, it could potentially hamper storm formation, said Colorado State University climatologist Phil Klotzbach. Cooler waters also remain near the equator and in the western Atlantic.

"I'd say we're still on pace for an active season. But we're going to be watching those cool anomalies closely," he said. "We might have to lower our forecast [18 storms, nine hurricanes] in early August."


With the expectation of named storm days east of 75W this month, they'll be foolhardy to cut down their numbers. That did not even happen in 2010 and we still got 19 storms.
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1455. Dakster
Quoting 1452. taco2me61:

Thanks Dakster :o) and I forgot it had to be a Major while going through the Box.... :o)

Taco :o)



No problem. Glad you took it constructively. ;)
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Quoting 1444. MississippiWx:


The comparisons to Ivan need to stop. Lol. Ivan was in September, the heart of hurricane season during a hyperactive season. While it's possible 95L could turn into something formidable eventually, it has very little model support for strengthening into much of anything for a while.
Agreed but good luck. Ever since IVAN every Cape Verde L and numerous waves that's come down the pike or anywhere near the same pike has been touted as IVAN part 2.
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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.