July Atlantic hurricane outlook

By: Dr. Jeff Masters , 12:55 PM GMT on July 13, 2012

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It's mid-July, and we have yet to see a named storm form in the Atlantic this month. The computer models are not predicting any development through at least July 20, and if we make it all the way to the end of the month without a named storm forming, it will be the first July since 2009 without a named storm. Since the current active hurricane period began in 1995, 13 of 17 years (76%) have had a named storm form during July. The busiest July occurred in 2005, when five named storms and two major hurricanes formed. These included Hurricane Dennis and Hurricane Emily--the strongest hurricanes ever observed so early in the season. Only eight major hurricanes have formed in July since record keeping began in 1851. As seen in Figure 1, most of the last half of July activity occurs in the Gulf of Mexico and waters off the Southeast U.S. coast. These type of storms form when a cold front moves off the U.S. coast and stalls out, with the old frontal boundary serving as a focal point for development of a tropical disturbance (as happened for Alberto, Beryl, Chris, and Debby in 2012.) There will be at least two cold fronts moving off the U.S. Mid-Atlantic coast over the next two weeks. The first of these fronts will push offshore around July 20, and we will need to watch the waters offshore of North Carolina for development then. Formation potential will be aided by ocean temperatures that are about 0.7°C (1°F) above average along the U.S. East Coast.


Figure 1. Tracks of all tropical storms and hurricanes 1851 - 2006 that formed July 16-31. The U.S. coast from North to Texas are the preferred strike locations. Only a few storms have formed in the tropical Atlantic and Caribbean in July. Wind shear is typically too high and SSTs too cool in July to allow African waves in the Caribbean and tropical Atlantic to develop into tropical storms. However, a few long-track "Cape Verdes" hurricanes have occurred in July, spawned by tropical waves that came off the coast of Africa. African tropical waves serve as the instigators of about 85% of all major hurricanes.


Figure 2. The seasonal distribution of Atlantic hurricane activity shows that July typically has low activity. Image credit: NHC.

Sea Surface Temperatures: slightly above average
The departure of Sea Surface Temperatures (SST) from average over the tropical Atlantic between Africa and Central America was about 0.3°C above average during June (Figure 3.) This figure has not changed much over the first two weeks of July. These temperatures are not warm enough to appreciably affect the odds of a July named storm or hurricane. The strength of the Azores-Bermuda high has been near average over the past two weeks, driving near-average trade winds. The latest 2-week run of the GFS model predicts continued average-strength trade winds through late-July, so SSTs should remain about 0.3°C above average during this period, due to average amounts of cold water mixing up from below due to the wind action on the water.


Figure 3. Sea Surface Temperature (SST) departure from average for July 12, 2012. SSTs were 0.3°C above average over the tropical Atlantic's Main Development region for hurricanes, from Africa to Central America between 10° and 20° North Latitude. Note the large region of above average SSTs along the Equatorial Pacific off the coast of South America, the hallmark of a developing El Niño episode. Image credit: NOAA/NESDIS

El Niño on the way?
For two consecutive weeks, ocean temperatures 0.5 - 0.6°C above average have been present in the tropical Eastern Pacific, which is right at the threshold for a weak El Niño episode. NOAA's Climate Prediction Center has issued an El Niño Watch, and gives a 61% chance that El Niño conditions will be present during the August - September - October peak of the Atlantic hurricane season. The likely development of a full-fledged El Niño episode means that Atlantic hurricane activity will probably be suppressed in 2012, due to the strong upper-level winds and high wind shear these events typically bring to the tropical Atlantic.


Figure 4. Sea Surface Temperature (SST) departure from average for the the equatorial Eastern Pacific (the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region"). El Niño conditions exist when the SST in this region rises 0.5°C above average. As of July 9, 2012, SSTs in the Niño 3.4 region had risen to 0.5°C above average. To be considered an "El Niño episode", El Niño conditions must occur for five consecutive months, using 3-month averages. Image credit: NOAA Climate Prediction Center.

Wind shear: above average
Wind shear is usually defined as the difference in wind between 200 mb (roughly 40,000 foot altitude) and 850 mb (roughly 5,000 foot altitude). In most circumstances, wind shear above 20 knots will act to inhibit tropical storm formation. Wind shear below 12 knots is very conducive for tropical storm formation. High wind shear acts to tear a storm apart. The jet stream has two bands of strong high-altitude winds that are currently bringing high wind shear to the Atlantic. The southern branch (subtropical jet stream) is bringing high wind shear to the Caribbean, and the northern branch (polar jet stream) is bringing high wind shear to the waters offshore of New England. This configuration often leaves a "hole" of low shear between the two branches, off the Southeast U.S. coast and over the Gulf of Mexico. The jet stream is forecast to maintain this two-branch pattern over the coming two weeks. Wind shear has been about 10 - 20% higher than average over the first two weeks of July, and is predicted to be mostly above average for the coming two weeks. This will cut down on the odds of a July storm.


Figure 5. Vertical instability over the Caribbean Sea in 2012 (blue line) compared to average (black line.) The instability is plotted in °C, as a difference in temperature from near the surface to the upper atmosphere. Thunderstorms grow much more readily when vertical instability is high. Instability has been lower than average, due to an unusual amount of dry air in the atmosphere, reducing the potential for tropical storm formation. Image credit: NOAA/NESDIS/CIRA.

Dry air: above average
As seen in Figure 5, there has been an unusual amount of dry, stable air in the Caribbean this year creating low levels of vertical instability. This has occurred due to a combination of dry air from Africa, and upper-atmosphere dynamics creating large areas of sinking air that dry as they warm and approach the surface. The Gulf of Mexico and tropical Atlantic between the coast of Africa and the Lesser Antilles have also seen low vertical instability this summer. June and July are the peak months for dry air and dust coming off the coast of Africa, and the Saharan dust storms have been quite active over the past two weeks. Expect dry air to be a major deterrent to any storms that try to form in the tropical Atlantic during July.

Steering currents: average
The predicted steering current pattern for the next two weeks is a typical one for July. We have an active jet stream bringing many troughs of low pressure off the East Coast of the U.S. These troughs are frequent enough and strong enough to recurve any tropical storms or hurricanes that might penetrate north of the Caribbean Sea. Steering current patterns are predictable only about 3 - 5 days in the future, although we can make very general forecasts about the pattern as much as two weeks in advance. There is no telling what might happen during the peak months of August, September, and October--we might be in for a repeat of the favorable 2010 and 2011 steering current pattern, which recurved most storms out to sea--or the unfavorable 2008 pattern, which steered Ike and Gustav into the Gulf of Mexico.

Summary: a below average chance of a July tropical storm
Given that none of the computer models are forecasting tropical storm formation in the coming seven days, SSTs are only slightly above average, and wind shear and vertical stability are above average, I'll go with a 30% chance of a named storm forming in the Atlantic during the remainder of July.


Figure 6. Hurricane Emilia over the Eastern Pacific at 20:35 UTC July 10, 2012. At the time, Emilia was a Category 3 hurricane with 125 mph winds. Emilia peaked earlier in the day as a Category 4 storm with 140 mph winds--the strongest hurricane in the East Pacific so far in 2012. Image credit: NASA.

An active Eastern Pacific hurricane season
It's been a very active start to the Eastern Pacific hurricane season, where we've already had six named storms, four hurricanes, and three intense hurricanes. A typical season has 4 named storms, 2 hurricanes, and 0 intense hurricanes by July 14. The formation of Tropical Storm Fabio on July 12 marks the 4th earliest formation of the Eastern Pacific's season's sixth storm. The record is held by the year 1985, when the season's sixth storm formed on July 2. Record keeping began in 1949.

Have a great weekend, everyone, and I'll be back Monday with a new post.

Jeff Masters

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Quoting washingtonian115:
Hmmm in what time frame is this?.

Very end of the run, about 15 days... We'll have to see if future runs pick up on it.
Member Since: February 11, 2012 Posts: 79 Comments: 7290
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1159. Patrap
ACE 24 Hour (Estimated) EPAM Protons
(Updates every 5 minutes)

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Here we go..


see the spike:

http://www.swpc.noaa.gov/rt_plots/mag_3d.html

Added edit: OPe, I see WXweatherboyMA got it in already
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Quoting MAweatherboy1:
12z GFS...

Hmmm in what time frame is this?.
Member Since: August 14, 2010 Posts: 10 Comments: 15704
1156. Buhdog
Quoting GeorgiaStormz:


not really, thats more just windflows in opposite directions any rotation is very slight


not saying its at the surface, but i can see it clear as day...as light as it may be. Storms in S fl are far more than expected, I think they are related.
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Quoting nigel20:

Hey MA...what's up?


i just think its funny that we call him MA which is like Ma
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Quoting MrMixon:
We're seeing a little activity now - needles started climbing about an hour ago.




Bit of a spike on the magnetometer, lol...

Member Since: February 11, 2012 Posts: 79 Comments: 7290
Remember the image last night of 12/21/12? I'm making a better one now, stay tuned!
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Quoting GeorgiaStormz:
Wow. What a difference a year makes.

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Quoting nigel20:

Hey MA...what's up?

Hey Nigel, I'm doing well... Trying to keep cool, lol... It'll be close to 90 up here for the next 5 days... I'm not used to that kind of stuff!
Member Since: February 11, 2012 Posts: 79 Comments: 7290
Quoting Buhdog:
rotation in the fl straits

Link


not really, thats more just windflows in opposite directions any rotation is very slight
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1149. MrMixon
We're seeing a little activity now - needles started climbing about an hour ago.



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Quoting washingtonian115:
Let's agree to disagree shall we?.


we shall
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1147. Patrap


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1146. nigel20
Quoting MAweatherboy1:
12z GFS...


Hey MA...what's up?
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1145. Buhdog
rotation in the fl straits

Link
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Quoting GeorgiaStormz:


3 in August
3 in September
1 in October
0 in November
Let's agree to disagree shall we?.
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12z GFS...

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1142. Patrap
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Quoting TropicalAnalystwx13:

7 more named storms between the two most active months of the hurricane season, not to mention the slightly slower October and November?

That doesn't seem right..


3 in August
3 in September
1 in October
0 in November
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1140. bappit
I think the season is a stud. Four named storms so far. Might draft it for my fantasy hurricane season. Keeper league,right?
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1139. nigel20
Quoting hurricanehunter27:
Captured by the international space station crew. The picture shows red sprites hovering just above an intense thunderstorm.


Very nice, hh27!
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Quoting GeorgiaStormz:


what is FPSMDH?

And i say 11-4-2, no storms till august.
There could be a US landfall, idk if there will be or not.
It means face palm shaking my damn head.This is one of those season where people have to see it to believe it.
Member Since: August 14, 2010 Posts: 10 Comments: 15704
Quoting GeorgiaStormz:


what is FPSMDH?

And i say 11-4-2, no storms till august.
There could be a US landfall, idk if there will be or not.

7 more named storms between the two most active months of the hurricane season, not to mention the slightly slower October and November?

That doesn't seem right..
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Quoting GTcooliebai:
I was noticing that yesterday. Along the west coast of FL. we have been receiving rain everyday for the past week and more is on the way for next week. I would think this wetness would be considered a pattern as the dry air that was in the Gulf last year is no longer there this year and we saw only one storm develop in the Gulf, this year we've had Debby so far and we're only a month and half in to the Hurricane Season with Aug. Sep. Oct. and Nov. still to come. A bit of foreshadowing?


They are talking about some dry air arriving later next week but I don't buy it, if it does arrive it will likely be short lived for a couple days maybe. The way the pattern has been is more comparable to how it used to be in Florida and I believe we will stay in that.

Granted not every day is going to be as stormy as others. For example, despite very high moisture the coverage on Thursday and Friday wasn't that great. Why? Because after 3 days of widespread strong thunderstorms and some severe around, with such a tropical air mass in place you get a very efficient transport of latent heat into the upper atmosphere, this produced a a stable layer to form on Thursday and still somewhat yesterday. However, the atmosphere will soon return to a more unstable condition, making the atmosphere more favorable for strong to severe thunderstorms with massive amounts of lightning once again.


My point is there will be of course briefly some drier weather for a day or 2 but I don't expect an extended period of drier weather. We only had one after Debby because tropical systems sitting around like that for a while disrupt the normal pattern and Debby allowed a huge trough to dig into the area bringing dry air. Now though, the summer pattern for once has finally established and it's locked deeply in place. I expect more widespread thunderstorms to return tomorrow with higher moisture returning and much more unstable air, once again there will be a threat for strong to severe thunderstorms and most thunderstorms will produce numerous lightning strikes, expect destructive lightning with strong to severe cells.

I suspect 40% is too low for tomorrow, I'm thinking at least 50% maybe even 60% returning tomorrow, again on Monday and into Tuesday probably as well.


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Quoting washingtonian115:
If I could I'll give this post a 100000000000000+.It's real sad that some people aren't taking this season series because they think El nino will save their @&*.Real sad.Even some bloggers who I would expect more sense from say they aren't really anticipating much from this season and it'll just be another one of those El nino years that go into the book quietly without a sound.FPSMDH.


what is FPSMDH?

And i say 11-4-2, no storms till august.
There could be a US landfall, idk if there will be or not.
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Captured by the international space station crew. The picture shows red sprites hovering just above an intense thunderstorm.

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1133. nigel20
Hopefully everyone is having a good weekend so far...good afternoon!
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Quoting opal92nwf:
Hey everyone! I was just reading comments that were posted shortly after this blog was written, and I was alarmed of the complacency and stubborness that some people have about the El Nino forming. Unfortunately, some people believe that just because an El Nino is forming, this makes the season a dud and that we don't have to worry about significant development and just party on instead. This is not the case! We should be all the more prepared! Years like 1992, 1983, or 1965 (el nino) were so lacking in storms more than this year and then BOOM! a major hurricane strike caused untold misery and destruction. Whether or not the El Nino conditions affect the Atlantic in or after August, we should be prepared regardless! Also, climatology is starting to go against us in some parts of the country like Florida, where we have not seen a hurricane since 2005. Climatologically, parts of South Florida see a hurricane every 3-4 years. Despite all this said, though, I am not saying for sure this will happen, as I wouldn't be suprised if this year was a dud (in the sense of no significant hurricane strikes), BUT, keep watching and DON'T let your guard down, anyone should be ready for the rest of the season for a damaging hurricane strike.
If I could I'll give this post a 100000000000000+.It's real sad that some people aren't taking this season series because they think El nino will save their @&*.Real sad.Even some bloggers who I would expect more sense from say they aren't really anticipating much from this season and it'll just be another one of those El nino years that go into the book quietly without a sound.FPSMDH.
Member Since: August 14, 2010 Posts: 10 Comments: 15704
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Hey everyone! I was just reading comments that were posted shortly after this blog was written, and I was alarmed of the complacency and stubborness that some people have about the El Nino forming. Unfortunately, some people believe that just because an El Nino is forming, this makes the season a dud and that we don't have to worry about significant development and just party on instead. This is not the case! We should be all the more prepared! Years like 1992, 1983, or 1965 (el nino) were so lacking in storms more than this year and then BOOM! a major hurricane strike caused untold misery and destruction. Whether or not the El Nino conditions affect the Atlantic in or after August, we should be prepared regardless! Also, climatology is starting to go against us in some parts of the country like Florida, where we have not seen a hurricane since 2005. Climatologically, parts of South Florida see a hurricane every 3-4 years. Despite all this said, though, I am not saying for sure this will happen, as I wouldn't be suprised if this year was a dud (in the sense of no significant hurricane strikes), BUT, keep watching and DON'T let your guard down, anyone should be ready for the rest of the season for a damaging hurricane strike.
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Quoting Patrap:


The weather is a tad outside my sphere of influence, but I can def help with the second.


www.bestofbatonrouge.com/restaurants

Personal Favorite Restaurant
Mason's Grill




THANKS!!

My wife insists on going to Louisiana at least twice a year, just for the food. Not that I mind.
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Quoting wxchaser97:
1710 CHASE CROSSING ACCOMACK VA 3776 7567 TORNADO NEAR THE INTERSECTION OF CUSTIS NECK ROAD AND DRUMMANDTOWN RD. NUMEROUS TREES UPROOTED AND SOME BUILDING DAMAGED. FIRE AND EMS RESPONDING. (AKQ)


likely gone now:
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I've got to go get my haircut, be back in 30mins-1 hr.
Member Since: March 16, 2012 Posts: 123 Comments: 7885
CI# /Pressure/ Vmax
4.4 / 980.9mb/ 74.6kt


Final T# Adj T# Raw T#
4.3 4.7 5.8

Estimated radius of max. wind based on IR : 20 km

Center Temp : +6.0C Cloud Region Temp : -64.9C

Scene Type : EYE

Positioning Method : RING/SPIRAL COMBINATION

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : PACIFIC

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : ON
Rapid Dissipation Flag : OFF
Member Since: March 16, 2012 Posts: 123 Comments: 7885
If Fabio can wrap that convection around just a little more and get that eye a little warmer, it sould be declared a Category 2.

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1710 CHASE CROSSING ACCOMACK VA 3776 7567 TORNADO NEAR THE INTERSECTION OF CUSTIS NECK ROAD AND DRUMMANDTOWN RD. NUMEROUS TREES UPROOTED AND SOME BUILDING DAMAGED. FIRE AND EMS RESPONDING. (AKQ)
Member Since: March 16, 2012 Posts: 123 Comments: 7885
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1121. Patrap
Quoting OldLeatherneck:


Hey Patrap,

Wife & I are headed to SE Texas and Louisiana next week. Would appreciate if you could order up at least 1 day of sunshine!

If you can't do that, do you know of any good restaurants in Baton Rouge??


The weather is a tad outside my sphere of influence, but I can def help with the second.


www.bestofbatonrouge.com/restaurants

Personal Favorite Restaurant
Mason's Grill


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Quoting Patrap:


Hey Patrap,

Wife & I are headed to SE Texas and Louisiana next week. Would appreciate if you could order up at least 1 day of sunshine!

If you can't do that, do you know of any good restaurants in Baton Rouge??
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1118. hydrus
Quoting bappit:

That process occurs whether we have TC's or not. Since TC's are infrequent at best, the 24 x 7 events do the job.
True, and if we did not have those 24/7 events, tropical cyclones would be even more powerful than they already are.
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1116. KEEPEROFTHEGATE (Mod)
Quoting MontanaZephyr:
oooo...

Just had a pop-up commercial with audio!

Took me a minute t find where the gxd dxmned thing was coming from.

This site!

Some Gxd Dxmned Shxt about about buy some drugs.

I see the weather channel deal has already fuqed the site.

What a god dxmned drag.


well if ya paid the 10.00 dollar membership fee you would not have any ads

iam ad free been so since july 2006
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TORNADO WARNING
VAC001-141800-
/O.NEW.KAKQ.TO.W.0017.120714T1712Z-120714T1800Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE WAKEFIELD VA
112 PM EDT SAT JUL 14 2012

THE NATIONAL WEATHER SERVICE IN WAKEFIELD HAS ISSUED A

* TORNADO WARNING FOR...
CENTRAL ACCOMACK COUNTY IN SOUTHEAST VIRGINIA...

* UNTIL 200 PM EDT

* AT 106 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO. THIS DANGEROUS STORM WAS LOCATED 5 MILES EAST OF ONLEY...
OR 15 MILES NORTHEAST OF EXMORE...AND MOVING SOUTHEAST AT 5 MPH.

* THIS DANGEROUS STORM WILL AFFECT MAINLY RURAL AREAS OF CENTRAL
ACCOMACK COUNTY.

PLEASE SEND YOUR REPORTS OF HAIL AND OR WIND DAMAGE...INCLUDING TREES
OR LARGE LIMBS DOWNED...BY CALLING NOAA`S NATIONAL WEATHER SERVICE IN
WAKEFIELD AT...1...800...7 3 7...8 6 2 4.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE... OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 3766 7558 3764 7558 3763 7559 3763 7564
3769 7566 3772 7560 3770 7557 3767 7557
TIME...MOT...LOC 1712Z 330DEG 3KT 3768 7562
Member Since: March 16, 2012 Posts: 123 Comments: 7885
Fabio:EP, 06, 2012071412, , BEST, 0, 161N, 1138W, 80, 978, HU, 64, NEQ, 25, 25, 20, 25, 1009, 200, 20, 0, 0, E, 0, , 0, 0, FABIO, D,

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Convection almost fully around the eye now.
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.