97L a major rainfall threat; October hurricane outlook; NC rains finally end

By: Dr. Jeff Masters , 2:08 PM GMT on October 01, 2010

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A large and complex region of disturbed weather (Invest 97L), centered about 800 miles east of the Lesser Antilles Islands, is headed west-northwest at 15 - 20 mph and will bring heavy rain showers and gusty winds to the northern Lesser Antilles Islands on Saturday and Sunday. Wind shear is a moderate 5 - 15 knots over 97L, and the waters beneath are very warm, 29°C. However, recent satellite imagery shows that the intensity and areal coverage of 97L's heavy thunderstorms have decreased this morning, thanks to some dry air being ingested into the storm. The SHIPS model predicts that wind shear over 97L will rise to the high range, 20 - 30 knots, Saturday through Tuesday, but some of the global computer models depict only moderate amounts of shear for 97L during this period. The NOGAPS model is the only model currently showing significant development 97L, and that model predicts 97L will be near Puerto Rico on Monday, the Dominican Republic on Tuesday, Haiti on Wednesday, and Eastern Cuba and the southeast Bahamas on Thursday. NHC is giving 97L a 40% chance of developing into a tropical depression by Sunday, but as of this morning, had not tasked the Hurricane Hunters to fly into the storm over the next two days. 97L will slow down to 5 - 10 mph on Sunday, bringing the potential for an extended 3 - 4 day period of heavy rains for the islands in its path. Even if 97L does not develop into a tropical depression, its slow motion may result in life-threatening flash flooding and mudslides in Puerto Rico, the Dominican Republic, Haiti, and eastern Cuba next week.


Figure 1. Morning satellite image of Invest 97L.

October hurricane outlook
October is here, and it is time to take stock of where we stand and how far we have to go before hurricane season is over. The beginning of October traditionally marks the two-thirds point of hurricane season; approximately one-third of all hurricanes and 28% of named storms occur after October 1. Tropical Storm Nicole brought us up to fourteen named storms for the year, and I expect about 4 - 5 more named storms this year with 2 - 3 of these being hurricanes. That would add up to 18 - 19 named storms for the season, putting 2010 in 3rd - 5th place all-time for most named storms. Since record keeping began in 1851, only four seasons have finished with more than eighteen named storms. These seasons were 2005 (28 named storms, with the 17th named storm, Rita, occurring by October 1); 1933 (21 named storms, with the 18th named storm occurring by October 1;) 1995 (19 named storms, with the 15th named storm, Opal, occurring by October 1;) and 1887 (19 named storms, with the 10th named storm occurring by October 1.) The most likely time to get activity is during the first two weeks of October. There are still two weeks of peak hurricane season left before the activity traditionally begins to decline steeply (Figure 2.) Given the record warm sea surface temperatures in the Atlantic this fall, the presence of La Niña in the Eastern Pacific keeping wind shear lower than average, and the observed increase in late-season activity in recent decades, I expect this year's peak portion of hurricane season will last until the end of October. I predict three named storms, two hurricanes, and one intense hurricane will form in the Atlantic this month, with two named storms and one hurricane occurring in November - December, making 2010 as the third busiest Atlantic hurricane season of all-time.


Figure 2. Climatological frequency of Atlantic named storms and hurricanes.

Jamaica cleans up after Nicole
Tropical Storm Nicole lasted only six hours as a tropical storm, but the storm's torrential rains hit Jamaica hard. Nicole's rains killed at least six people on the island, and at least thirteens others are missing and feared dead. The storm cut power to 170,000 island residents, and caused millions of dollars in damages. Wunderground member JamaicaZed wrote me to say his rain gauge in the Kingston suburb of Norbrook caught 17.39" of rain Monday through Thursday, with 11.10" coming on Wednesday.

Historic rainfall event for eastern North Carolina ends
The rains have finally ended In North Carolina, where tropical moisture streaming northward in advance of Nicole generated a historic rainfall event this week. Wilmington, NC set records this week for the heaviest 3-day, 4-day, and 5-day rainfall events in city history, and the month of September ended up as the second rainiest month ever recorded in the city. A remarkable 22.54" of rain fell on Wilmington during the 5-day period Sunday through Thursday. The previous record was 19.06", set in September 1999 during Hurricane Floyd. Fortunately, eastern North Carolina was under moderate drought conditions prior to this week's rainfall onslaught, with just 0.18" of rain falling during the first 25 days of September. Only minor to moderate flooding is occurring on North Carolina rivers, with just one river, the Northeast Cape Fear River near Chinquapin, expected to experience major flooding. Portlight.org is beginning to identify needs in Eastern North Carolina in the wake of the flooding, and expects to perform the first deployment of their new relief trailer within the next few days and send a truck loaded with water, food and personal hygiene supplies.

The most remarkable thing about Wilmington's second-wettest month in history is that it came without a hurricane affecting North Carolina. All four of the other top-five wettest Septembers in history were due, in large part, to hurricanes:

#1 23.41 inches 1999 (Hurricanes Dennis and Floyd)
#2 22.72 inches 2010 (plume of tropical moisture in advance of TS Nicole)
#3 20.10 inches 1877 (Hurricane Four)
#4 18.94 inches 1984 (Hurricane Diana)
#5 16.93 inches 1924 (Hurricane Five and Tropical Storm Eight)


Figure 3. Radar-estimated precipitation for North Carolina since Sunday shows that the precursor moisture from Nicole has brought widespread rain amounts of fifteen inches (white colors.)

Heavy rains and flooding for New England
The plume of tropical moisture that affected North Carolina is now triggering heavy rains in New England, and flood warnings are posted throughout most of New Jersey, eastern Pennsylvania, eastern New York, Delaware, and Vermont this morning. In New York City, heavy rains this morning have overwhelmed one section of the city's subway system, and flooding closed several key road arteries in the city, snarling the morning commute. About two inches of rain have fallen so far this morning in the city. Severe weather is not expected, and no tornadoes were reported yesterday in association with this weather system.

Elsewhere in the tropics
Disturbed weather continues in the Central Caribbean, where the remnants of Tropical Storm Nicole will bring isolated heavy rain showers today to Hispaniola, Jamaica, Cuba, the Cayman Islands, and northern Honduras. The GFS model predicts this activity will concentrate near Hispaniola over the weekend, then push northwards into the Bahamas, with a subtropical or extratropical storm forming over the Bahamas on Sunday or Monday. This storm could bring 2 - 4 inches of rain to the Bahamas Sunday and Monday. The storm will then move north-northeastwards, parallel to the U.S. East Coast, and not affect any other land areas. Several of the models are predicting the formation of a tropical depression in the Mid-Atlantic 5 - 7 days from now, in a location that would not be of any danger to land areas.

Next update
I'll have an update Saturday morning.

Jeff Masters

Flooding (jdwagon)
Shannon Hills, Ridgeway, VA
Flooding
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Quoting lhwhelk:
Hurricane History: Since things are a little slow, and since several bloggers on here know everything--VBG--I would like to ask if anyone knows about a hurricane from the dim and distant past. I grew up in the Lower Rio Grande Valley of Texas (Brownsville, Weslaco, Mission). When my parents moved there in 1943, all of the very tall palm trees were bent into a zig-zag shape--straight up from the ground, then a kink to the north/right, then straight up again. They were told, and told me, that this had been caused by a hurricane that bent the palms down and that they then retained that bend. They were also told that the same hurricane had destroyed a hotel on South Padre Island, blowing a grand piano from the hotel across the Laguna Madre in to Port Isabel. I've not been able to find an appropriate hurricane to match this story. Anyone know anything about this?


"The first storm of 1931 made landfall in the Galveston area as a tropical storm.

A tropical storm formed August 11th in the southern Gulf of Mexico near the Yucatán Peninsula and slammed into the upper Texas coast near Freeport, Texas as a very compact Category 4 hurricane two days later. As the storm moved over the Gulf of Mexico, it intensified from a Category 1 to a Category 4 with winds estimated at 140 mph and an estimated central pressure of 942 millibars in less than one day. The eye crossed the coast about 10 p.m. on August 13, slashing a 30- to 40-mile wide path of destruction across Brazoria County, Texas. Official warning for the storm came just 4 hours prior to landfall, and many people trying to evacuate inland had to abandon their cars in high winds and heavy rains. The 1932 hurricane retained its strength miles from the coast and killed 40 people. The greatest single toll for any town was 7 in West Columbia, Texas, where sustained winds over 100 mph flattened homes. Two neighborhoods that had been constructed for oil industry workers there were wiped clean. Freeport, Angleton and Galveston suffered extensive wind damage, and the inland towns of Brazoria, West Columbia, Damon and Needville, all in the path of the eye, were also devastated. Damage estimates topped $7 million in 1932 U.S. dollars.

The Texas area was alive with activity in 1933, with the second storm making landfall in Mexico after threatening Texas; the fourth storm making landfall near Matagorda Bay in Texas as a 45 mph (70 km/h) tropical storm on July 23. The fifth storm made landfall near Brownsville, Texas on August 5 as a strong tropical storm. The storm produced strong winds and high tides along the coast of Texas, while heavy rains in south Texas and northern Mexico caused heavy damage. High tides from the storm covered parts of South Padre Island. The tenth storm threatened Texas, causing the issuance of tropical storm warnings for portions of the southern Texas coastline. The eleventh storm made landfall just north of Brownsville early on September 5. 179 people were killed and doing 28 million dollars in damage.


In 1934, the third storm was a Category 1 hurricane passed over north Florida as a tropical storm and made landfall in central Texas, causing 11 casualties and $1-$2 million in damage. The fifth storm was another Category 1 hurricane that grazed Galveston.

The third storm of the 1936 season caused severe crop damage was reported in San Patricio and Nueces Counties. In all, the hurricane caused $550,000 (1936 USD) in damage, primarily to oil refinery property, though no deaths or injuries were reported. The fourteenth storm of the season made landfall near Brownsville.

The third and fifth storms of 1938 made landfall in the state."

The 1940's had some storms...all of them made landfall North of Galveston however.

Hope this helps :)

Member Since: July 6, 2010 Posts: 113 Comments: 31860
BUSY, BUT LITTLE IMPACT ON U.S. AND THE SEASON IS QUICKLY ENDING!
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466. bwi
Good evening. I'm a little surprised by the location of NHC's 20% circle out in the Atlantic. I know they've been following that area, but it seems that whatever hints of circulation might exist would seem to be further west closer toward the islands. Winds south at buoy at 14.5n 53w and hinting SSW at 14.5 56w.
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Quoting ncweatherenthus:
http://www.wral.com/weather/story/8385446/

Windsor could use your help with over 50 people being evacuated by swift water rescue teams and Coast Guard helicopters. There are a lot of little towns that are under water right now. We haven't heard much in terms of what the state is planning to do though. Just a mess for everyone along and east of I-95.


Thanks nc. I am headed up that way early in the morning to begin identifying communities that are a good fit for the Portlight mission. Specific information and contacts have been hard to come by today, but being in the area tomorrow should make things much easier. So far it seems that Swansboro, Bertie, and Hubert may be some of the areas we begin in. We are also prepared to assist in anyway we can while we are also carrying out an assessment. The Portlight Live Webcam will be running for much of this trip and you can view it here beginning tomorrow morning.

Have to finish getting ready to leave so I can get a little sleep before I head out at about 5am. Y'all have a good night.
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464. JLPR2
A line of convection...
hmm...
So anyone got any theories as to why it is so linear?

Member Since: September 4, 2007 Posts: 7 Comments: 8641
Hurricane History: Since things are a little slow, and since several bloggers on here know everything--VBG--I would like to ask if anyone knows about a hurricane from the dim and distant past. I grew up in the Lower Rio Grande Valley of Texas (Brownsville, Weslaco, Mission). When my parents moved there in 1943, all of the very tall palm trees were bent into a zig-zag shape--straight up from the ground, then a kink to the north/right, then straight up again. They were told, and told me, that this had been caused by a hurricane that bent the palms down and that they then retained that bend. They were also told that the same hurricane had destroyed a hotel on South Padre Island, blowing a grand piano from the hotel across the Laguna Madre in to Port Isabel. I've not been able to find an appropriate hurricane to match this story. Anyone know anything about this?
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I didn't really mean the 8PM TWo was at 30%.

It was just a guess...I got it wrong :(
Member Since: July 6, 2010 Posts: 113 Comments: 31860
Quoting sailingallover:

Is that not a trough to shear them and pick them up and take them NE?
But yes we are seeing some late waves. But the reason CV season is considered over as I mentioned earlier is troughs and fronts start picking the waves off very quickly before they can make it across the Atlantic. Shear increases, SST drop rapidly from the Canaries current and fronts start making it down into africa as well.
Yes there could be a late season waves that defies odds/fronts and everything and comes all the way across and creams us as a CAT 5. I don't think it's ever happened but I'd be interested if you find something.
Here is one for you...Link ......The Great Hurricane of 1780...200 mph winds.!.... Oct-9 thru Oct-20...
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An (almost) final thought for the "season is over" crowd: below is a graphic showing every post-September hurricane and tropical storm in the Atlantic over the last 100 years. If you look closely, you may be able to see one or two. ;-)

Click for larger image:

Appropriate tropical weather-related image
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the area near 10n and 40w looks more interesting tonight than 97L.
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Quoting hydrus:
Neat pic Chuck...I still believe the Cape Verde Season still might have a couple more storms for the Atlantic Basin. Just my harmless opinion..


I agree, at least one maybe two more named storms from the disturbances rolling off the African coast
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Quoting hydrus:
Someone said the Cape Verde season is over. Are these not waves moving across Africa?...

Is that not a trough to shear them and pick them up and take them NE?
But yes we are seeing some late waves. But the reason CV season is considered over as I mentioned earlier is troughs and fronts start picking the waves off very quickly before they can make it across the Atlantic. Shear increases, SST drop rapidly from the Canaries current and fronts start making it down into africa as well.
Yes there could be a late season waves that defies odds/fronts and everything and comes all the way across and creams us as a CAT 5. I don't think it's ever happened but I'd be interested if you find something.
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Quoting sailingallover:

But we will get RAIN..a lot of rain..then some more rain..and after that..rain.


yes, we should see rain that can cause some flooding, that's correct.
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Quoting PanhandleChuck:
Neat pic Chuck...I still believe the Cape Verde Season still might have a couple more storms for the Atlantic Basin. Just my harmless opinion..
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Quoting sailingallover:

But we will get RAIN..a lot of rain..then some more rain..and after that..rain.
Hey,....I was wondering if you all are going to get any rain....
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452. JRRP
convection is increasing

i'll be back later
Member Since: August 16, 2007 Posts: 0 Comments: 5684
451. JLPR2
Quoting sailingallover:

But we will get RAIN..a lot of rain..then some more rain..and after that..rain.


I hate rain in the week -.-
I wish 97L would turn into a major so it could turn to the NE. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8641
Quoting WeatherfanPR:
NAM model still entertains me !!! but 97L is so boring right now and looks like is gonna pass north of us according to track models.

But we will get RAIN..a lot of rain..then some more rain..and after that..rain.
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Someone said the Cape Verde season is over..... Are these not waves moving across Africa?...
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Look at this mess...
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447. JLPR2
Quoting WeatherfanPR:
NAM model still entertains me !!! but 97L is so boring right now and looks like is gonna pass north of us according to track models.


Don't ignore it and give it till D-max, now if by d-max it doesn't manage anything, well then we can chill. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8641
NAM model still entertains me !!! but 97L is so boring right now and looks like is gonna pass north of us according to track models.
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Quoting CaptnDan142:


Why Igor?


It's believed that Environment Canada will likely request retirement of Igor, as they did with 2003's Hurricane Juan...
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Quoting CaptnDan142:


Question is, how much of it do you remember? ;-)


For some odd reason, I believe that there was a discussion about priests and me going to catholic school K - 12th grade. I was amazed that I did not get banned and no matter how much I drink tonight, I refuse to get on that topic again. LOL
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442. JLPR2
Quoting sailingallover:

Pressures are still high and ship reports don't show a circulation just a NE/SE wind vertex so not to much to worry about but we really need to watch this..Shear will keep it from organizing and is still 20-30knots over the upper half but if it gets a chance it will develop fast.


I modified that comment, it went back to being elongated on the 00z update, with the vort to the SW gaining presence, seems 97L is having a vortex fight. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8641
441. JLPR2
Hmm...
The CMC has the SW tail of 97L's vort winning out.


Although maybe it will dissipate completely. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8641
Quoting pilotguy1:


I suggest the Jager and Bud at this time. I doubt it will hurt anything.


You've been warned, I'll be right back.
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Quoting JLPR2:
97L's Vort is looking rounder.


Pressures are still high and ship reports don't show a circulation just a NE/SE wind vertex so not to much to worry about but we really need to watch this..Shear will keep it from organizing and is still 20-30knots over the upper half but if it gets a chance it will develop fast.
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Quoting PanhandleChuck:
I don't know if y'all remember about a week ago, don't make me break out the Jager and Bud Light again to liven up this crowd.


Question is, how much of it do you remember? ;-)
Member Since: August 21, 2007 Posts: 0 Comments: 856
436. beell
12Z Sunday Surface

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I don't know if y'all remember about a week ago, don't make me break out the Jager and Bud Light again to liven up this crowd.
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Complete Update


AOI
AOI AOI AOI

AOI AOI AOI

TS BUSTED FORECAST ALIBI
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432. beell
Quoting plywoodstatenative:
Bell: isn't that what did most of the damage with the rain, a coastal low that formed after the circulation of Nicole just about died out?


Pretty much. What made that mess bad was the very narrow moisture feed from the tropics training over the same area. Forced in between the trough to the west and strong ridging in the western Atlantic. Plenty of moisture advecting N from the Caribbean. The northern end of the system formed an extratropical low and the remnants followed behind.

That pattern still exists to a fair extent although the moisture maybe not quite as deep.

A wait and see. For now, maybe just a bit more rain for areas that don't need it. It would be sub-tropical at best.
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Quoting pilotguy1:

Sometimes when there is nothing to say silence is a good thing.


And sometimes when there is something to say.... silence is also best. LOL
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Quoting WeatherNerdPR:

I heard a quote on an article from up there that said Igor "Was a 50 to a 100 year event."


Here's an excerpt from the Wiki article:

Significant wind and flooding damage was reported across much of the island of Newfoundland as Igor passed just to the east. Many communities had to declare a state of emergency and some parts of the community of Clarenville were evacuated due to flooding. 238 mm (9.37 inches) of rain fell on the Burin Peninsula at St. Lawrence, making Hurricane Igor at least the third wettest tropical cyclone to be recorded in Canada

Being the third wettest storm would definitely put it in the 'rare events' category. I just don't think they'll retire it is all.
Member Since: August 21, 2007 Posts: 0 Comments: 856
Why was the 8PM update late.. it takes a REALLY long time to look at the mess in Atlantic/Carib and see if anything actually has potential to develop
I give up..This morning 97 was defined Vertex on ASCAT and RGB sat loops..now there is so much scattered convection and little vortices you cant find anything for sure!
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Quoting CaptnDan142:


It was bad up there, no doubt. Just not sure if they will see is as retirement worthy.

I heard a quote on an article from up there that said Igor "Was a 50 to a 100 year event."
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423: Most of this season has been that way, crazy, and just outright dumbfounding at times. I am interested to see what happens with the up and downgrading of these storms after its all said and done.
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426. JLPR2
97L's Vort is looking rounder.



Scratch that, the new one shows it elongated again. xD
Member Since: September 4, 2007 Posts: 7 Comments: 8641
Quoting MZT:
Ignore whacked Newfoundland pretty hard - parts of it were unreachable for weeks because of washed out roads.


It was bad up there, no doubt. Just not sure if they will see is as retirement worthy.
Member Since: August 21, 2007 Posts: 0 Comments: 856
If a coastal low were to form off of Florida, Ike, what then is the chance it would draw up the moisture laden environment that 97L is currently in?
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Quoting plywoodstatenative:
here is what interests me on this system, that being 97L: Its coming from a region that usually does not produce tropical systems this time of year. Normally we are watching the Gulf and Caribbean for storms, not the eastern Atlantic


An anomoly? Maybe that's why it has such a low chance attached to it.
Member Since: August 21, 2007 Posts: 0 Comments: 856
Bell: isn't that what did most of the damage with the rain, a coastal low that formed after the circulation of Nicole just about died out?
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421. MZT
Quoting CaptnDan142:


Why Igor?
Igor whacked Newfoundland pretty hard - parts of it were unreachable for weeks because of washed out roads.
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420. KYDan
Quoting WatchingThisOne:


Um, when the lettering on the chart is less than 1 point in size (for anyone on a high res monitor), could you (and other posters) please do us the favor of typing e.g. "OOZ NAM +84". Would save me dragging out the Windows magnifying glass each time. Thanks in advance.

WTO


Here is a suggestion that might help you, and I know it helps me. If you are using a pc, put the cursor on the image and right click, then choose "view image". The image will open in a new window at it's full size instead of the shrunken image you see here on the blog.

Dan
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here is what interests me on this system, that being 97L: Its coming from a region that usually does not produce tropical systems this time of year. Normally we are watching the Gulf and Caribbean for storms, not the eastern Atlantic
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Quoting MZT:
Earl and Matthew may be gone. Igor definately. I would not rule out the possibility that "six hour Nicole" could be retired either.

Perhaps this season will be a record-breaker in terms of names removed from use.

And yet we had so many in August ready to call the season a dud...


Why Igor?
Member Since: August 21, 2007 Posts: 0 Comments: 856

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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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