Irene roars into life; may become the season's first hurricane

By: Dr. Jeff Masters , 12:03 AM GMT on August 21, 2011

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Tropical Storm Irene roared into life this evening, transitioning from a tropical wave to a 50 mph tropical storm in just a few short hours. An Air Force hurricane hunter aircraft in the storm was finishing up its mission when it suddenly came across a region with intense thunderstorms and surface winds of 50 mph. The aircraft found that a center of circulation had barely closed off on the southwest edge of this region, though the plane found almost no winds from the west around the circulation center. The 6:10pm EDT center fix found a central pressure of 1007mb, which is quite high for the observed 50 mph winds. Dry air to the north and west is slowing development, as well as moderate wind shear of 10 - 20 knots, as analyzed by the University of Wisconsin CIMSS group. Infrared satellite loops and radar out of Martinique show the storm is poorly organized, with no evidence of spiral bands. The center of Irene is expected to cross over the Caribbean island of Dominica early Sunday morning, but the heaviest thunderstorms lie to the north of the center, and will affect Guadeloupe, Antigua, and St. Kitts and Nevis.


Figure 1. Evening satellite image of Irene.

The computer models have shifted southwards since yesterday, and now take Irene south of Puerto Rico on Monday, and along the south shore of the Dominican Republic on Tuesday. On Wednesday, Irene should pass near or over southern Haiti, Eastern Cuba, and Jamaica. On Wednesday and Thursday, the models agree that a trough of low pressure will dip down over the Eastern U.S., which is likely to turn Irene to the north. The exact timing and strength of this trough varies considerably from model to model, and will be critical in determining where and when Irene will turn to the north. We can expect that Irene will impact Central Cuba, the Bahamas, and the Florida Keys on Thursday, but it is uncertain whether Irene's turn to the north will take the storm into the Gulf of Mexico or not. Irene most reminds me of Tropical Storm Fay of 2008. Fay formed just off the coast of Puerto Rico, and was never quite able to get organized enough to become a hurricane, due to passage over Hispaniola and Cuba. Fay topped out as a strong tropical storm with 70 mph winds, and did over $500 million in damage in the U.S., mostly due to flooding rains in Florida that accumulated to over 25 inches in a few areas. Fay also dumped heavy rains on Hispaniola, triggering flooding that claimed eight lives.


Figure 2. Track of Tropical Storm Fay of 2008.

Irene will be battling dry air and moderate wind shear of 10 - 20 knots through Sunday, and it will take the storm 1 - 3 days to build up an eyewall and intensify into a hurricane. Irene is more of a threat than Tropical Storm Emily of early August was, since Irene has closed off a center farther east than Emily did and has more time to organize before encountering Hispaniola. I don't think passage over Hispaniola will destroy Irene, since it is a fairly large storm, and is likely to be a hurricane by then. However, if Irene follows the NHC forecast, it will have an extended encounter with Hispaniola and Cuba on Tuesday through Wednesday that will probably weaken the storm below hurricane force. Keep in mind that the average error for an official 5-day forecast from NHC for a developed storm is 200 - 250 miles. Irene could easily miss Florida and move up the East Coast and hit North or South Carolina, or pass through the Florida Keys and into Gulf of Mexico, ending up who knows where. Given the uncertainties, this weekend would be a good time to go over your hurricane preparedness if you live anywhere in the Caribbean, Bahamas, or U.S. coast, since Irene could well be paying you a visit as a tropical storm or hurricane sometime in the next week.

Harvey hits Belize
Tropical Storm Harvey made landfall at 2pm EDT on Saturday near Dangriga Town, Belize, as a tropical storm with 60 mph winds. Harvey continues to dump very heavy rains on northern Guatemala, Belize, and portions of Mexico's Yucatan Peninsula as the storm tracks westwards at 12 mph. Dissipation is expected Sunday as the storm pushes inland. Harvey was a small storm, and the strongest winds were confined to a short stretch of coast near where the center came ashore. Winds at Belize City, Belize on Saturday topped out at 15 mph.


Figure 3. Radar image of Harvey taken at 11:30am EDT on Saturday, August 20, 2011, a few hours before landfall in Belize. A small closed eye is visible just south of the offshore islands of Belize. Image credit: Belize National Meteorological Service.

An exceptionally active early part of hurricane season
It's been a strangely hyperactive season for weak storms in the Atlantic so far this year. Tropical Storm Irene is the 9th named storm this year, and its formation date of August 20 ties 2011 with 1936 as the 2nd earliest date for formation of the season's 9th storm. Only 2005 had an earlier date. The first eight storms this year have stayed below hurricane strength, making 2011 the first hurricane season since record keeping began in 1851 to have more than six consecutive tropical storms that did not reach hurricane strength. As I discussed in Friday's post, a major reason for this is the lack of vertical instability over the tropical Atlantic so far this year. We've had a large amount of dry, sinking air over the tropical Atlantic, and the usual amount of dry, dusty air from the Sahara, both helping to keep the atmosphere stable and stop this year's storms from intensifying into hurricanes. Hurricane activity typically ramps up big-time by August 20, with more than 80% of all the hurricanes and 65% of all the tropical storms occurring after that date. At our current pace, 2011 will become the second busiest Atlantic hurricane season on record, with 24 - 27 named storms. There are only 21 names in the list of names for a hurricane season, so we may have to break out the Greek alphabet again in late October this year, as occurred in 2005. Ironically, this was the last time the current set of names was used in the Atlantic, so 16 of this year's 21 names are repeats of 2005. I'm not too happy about seeing another hurricane season challenge the Hurricane Season of 2005 in any way, and let's hope we don't retire another five names this year, like occurred in 2005! With vertical instability much lower this year than in 2005, and that year having already seen one storm (Dennis) retired by this point in the season, I doubt that will happen, though.


Figure 2. The annual cycle of average hurricane frequency in the Atlantic. Historically, about 35% of all the tropical storms and 15% of all the hurricanes will have occurred by August 20.

Invest 98L near the Cape Verde Islands
A tropical wave near Cape Verde Islands off the coast of Africa, Invest 98L, is spreading heavy rains and strong gusty winds to those islands today. So far this morning, top sustained winds measured in the Cape Verde Islands were 23 mph at Mindelo. 98L has a long stretch of ocean to cross before it could affect any land areas. Approximately 70 - 80% of all tropical cyclones that pass this close to the Cape Verde Islands end up curving out to sea and not affecting any other land areas, according to Dr. Bob Hart's excellent historical probability of landfall charts. The latest set of long-range model runs go along with this idea, and I'd be surprised if 98L threatens any land areas.

Jeff Masters

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Hard to keep up with the blog so if this was mentioned... Sorry.
Anyone looked at the radar out of the French Antilles? To my very untrained eye it seems the center would cross Guadalupe. If so, north of what was thought.
Thoughts?
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Invest 97L appears nearly closed also.
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Quoting 3211976:

That's a cool looking image. Good job.
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Quoting stormpetrol:
Link

Look at this and tell me where u see the LLC, I see it at 13.8N/60.3W
Yes I definitely see a spin there.
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Quoting JrWeathermanFL:

Dont listen to him. He has like 30 screen names. I have deleted 22 of them. I dont know much about him. But ask Taz.


You have mail.
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Quoting stormwatcherCI:
Where in Cayman are you ?


South Sound area... you?
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Quoting yoboi:


where is it going???

Put him on ignore. He is bad for the blog. I'm fairly new but he has like 30 screen names. Ask one of the older bloggers.
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262. JLPR2
Quoting MiamiHurricanes09:
Wow, quite the northward shift.

AL, 09, 2011082100, 03, TVCN, 24, 165N, 650W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 36, 173N, 666W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 48, 180N, 696W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 60, 190N, 716W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 72, 199N, 735W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 84, 208N, 752W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 96, 222N, 767W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 108, 238N, 780W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 120, 256N, 792W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 132, 283N, 800W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 144, 298N, 806W, 0, 0, , 0, , 0, 0, 0, 0,


That's just 44miles to the south of PR.
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Quoting CybrTeddy:


Any chance you could post a image of the latest TVCN run if possible?


TVCN, DSHIP, and OFCI

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If the center of Irene was to reconsolidate to the NE would that put us all in the clear as far as the Fla. panhandle/ big bend is concerned...Im not liking that gfdl track..
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JMA shows gulf, but here's it's problem. Look at where it has Irene tomorrow morning:

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Only time will tell where this is going. It has a done a great job of mixing out the dry air and moistening its own environment. Its large size helped itself on that front.
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T.C.F.W.
09L/TS/I/CX
MARK CENTRE FIX
16.63N/57.71W
Member Since: July 15, 2006 Posts: 169 Comments: 53296

Quoting dfwstormwatch:

and the model ends with a pressure of 920 MB going through the Yucatan peninsula .................. WELL THAT'S JUST WONDERFUL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!



Down the Rabbit Hole we all go..

Thats Low,,and Big

And On the prowl


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255. JLPR2
I got a rather bad sign here.
Crickets are mysteriously quiet...
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Quoting watercayman:


Yeah, and us in Cayman too. Not liking that grudge at all, but something I've been a bit worried about...
Where in Cayman are you ?
Member Since: October 9, 2008 Posts: 0 Comments: 8266
Quoting bocahurricane:


Oh he is definitely not cancelling the trip, it just makes me nervous being in the "cone of doom" and being alone. Obviously I am a serious tropical system watcher and will be monitering the situation closely.


if you really are nervous about it, then FAU used to run a service were you could advertise for students to help. pretty sure that some college students would be happy to earn those extra bucks. however, would not wait until the last moment to decide . . . contact them on monday. At least they used to provide a service, check to see if it still exists.
trying to hire professionals (at this late stage in the game) may not be possible.
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Link

Look at this and tell me where u see the LLC, I see it at 13.8N/60.3W
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Quoting CybrTeddy:


Any chance you could post a image of the latest TVCN run if possible?
A northward shift wasn't just quite the correct working on my part...more like a shift towards the right.

Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Stormchaser2007:
00z TVCN has less Cuba and more water.

Also goes east of Florida.



thats not good
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Quoting Levi32:


They would probably have to shift at least slightly if a reformation occurs. There is no guarantee that it will, but it may if the convection continues to fire strongly north of the surface center.


Thanks. I feel like the next 24-48 hours will determine whether or not this is a threat to me in SE NC, being on the eastern fringe of the current "cone".
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247. MZT
The must be a lot of confidence in the models, being so tightly clustered on Florida. I am already seeing mentions of tropical weather in the NWS extended forecast for Charlotte:

It seems reasonable to expect some part of the southeast to be in some danger from a tropical cyclone shown by the collection of model guidance in the vicinity of the Florida Peninsula next Saturday. ... Have gone with a blanket chance of precipitation through the end of the day. People across the Carolinas will want to keep track of this one for Saturday night and Sunday.
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246. ackee
its seem like the models are split into two camps a west idea is not out of question also turn to north is also possible guess we just have to wait and see
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245. yoboi
Quoting JasonCoolMan2008:
Irene is no good guys,I tell you that!!! Ok i may be get scared now!!!


where is it going???
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Levi. Are you going to provide a new show for us to see tonight or do we wait for tomorrow?
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00z TVCN has less Cuba and more water.

Also goes east of Florida.
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Quoting JrWeathermanFL:

Dont listen to him. He has like 30 screen names. I have deleted 22 of them. I dont know much about him. But ask Taz.


I agree. I have 30 of them on my ignore list.

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Quoting daddyjames:
Quoting bocahurricane:
Hey everyone, I have been on this site for years mostly as a lurker. I have a question for some of experts on here. Normally I wouldnt be at that worried but I live in Palm Beach County and my husband is heading out of town on business tomorrow and won't be back till Friday. I have 2 kids (ages 1 and 3). I have a 6 bedroom 2 story house that will take me at least 2 days to shutter if I can't find someone to hire and do it for me. How concerned should I be and when do you think we are going to have a better idea exactly where, when and strength?

Seriously, bocahurricane. One option is that you have available to you (if all you need is muscle) is to advertise at the FAU - Boca campus (but well beforehand. Student employment services used to run a program that put people like you in touch with college students in need of $$$$. That's one way I helped pay the bills . . .


That is an great suggestion, I will definitely explore that option if needed. Thanks :)
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Quoting Verdog:


I agree, I don't think we have a way out of this one, unfortunately.

Dont listen to him. He has like 30 screen names. I have deleted 22 of them. I dont know much about him. But ask Taz.
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WOW, look at the nice OutFlow....
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Quoting MiamiHurricanes09:
Wow, quite the northward shift.

AL, 09, 2011082100, 03, TVCN, 24, 165N, 650W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 36, 173N, 666W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 48, 180N, 696W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 60, 190N, 716W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 72, 199N, 735W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 84, 208N, 752W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 96, 222N, 767W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 108, 238N, 780W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 120, 256N, 792W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 132, 283N, 800W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 144, 298N, 806W, 0, 0, , 0, , 0, 0, 0, 0,


Any chance you could post a image of the latest TVCN run if possible?
Member Since: July 8, 2005 Posts: 259 Comments: 23560


Guadeloupe radar
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Quoting Levi32:


It has a grudge on the gulf coast? I'm not sure, but it doesn't make a whole lot of sense. However, we have seen stranger things, which is why the gulf option remains open for now. Tomorrow will give us a better idea of what relation to Hispaniola this storm will have, as we should have a more defined and trackable center then with a clear long-term motion.


Yeah, and us in Cayman too. Not liking that grudge at all, but something I've been a bit worried about...
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odd Pressure is steady or rising at all stations? Link
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Quoting GTcooliebai:
Here's a wonderful site for all your computer model wonders Link enjoy ;)


Nice page. bookmarked. Thanks.
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Quoting 3211976:


Now I'm impressed if you took the time to align those two images so perfectly.
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Quoting GTcooliebai:
Good God!
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Quoting barotropic:


I wouldnt put the shutters up, nor would I cancel the trip. I would be a little patient and see what the NHC says and the models say the next couple runs. I would start to watch them more carefully tomorrow. It may be a tough call as if infact Irene goes over land toward S Florida, the intensity forecast may be somewhat of a coin toss.


Oh he is definitely not cancelling the trip, it just makes me nervous being in the "cone of doom" and being alone. Obviously I am a serious tropical system watcher and will be monitering the situation closely.
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Quoting KennyNebraska:


Why? The rigs and refineries in that part of the world have been closed by the EPA haven't they?


Not all the rigs were shut down, and they've started opening some areas up just recently. I don't think they shut down the refineries at all. But the refineries would be the structures most likely to cause gasoline to rise if they were knocked off line or couldn't recieve products.

The oil may come from other countries, but a large portion of overseas oil goes through the GOM.
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Quoting dfwstormwatch:
ill be back around 10-11 pm to post the 00z gfs,gdfl,hwrf, and maybe the ecmwf models


Thank you DFW, I appreciate it when you do that.
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Quoting KennyNebraska:


Yeah, you know in order for it to happen, Irene will have to experience the Atlantic high all the way through the next four days, with barely any influence from the trough that is supposed to be at full amplitude over the east CONUS some few days from now.

How likely is that?


I hope you are right. That makes me feel better.
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Quoting MiamiHurricanes09:
Wow, quite the northward shift.

AL, 09, 2011082100, 03, TVCN, 24, 165N, 650W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 36, 173N, 666W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 48, 180N, 696W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 60, 190N, 716W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 72, 199N, 735W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 84, 208N, 752W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 96, 222N, 767W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 108, 238N, 780W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 120, 256N, 792W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 132, 283N, 800W, 0, 0, , 0, , 0, 0, 0, 0,
AL, 09, 2011082100, 03, TVCN, 144, 298N, 806W, 0, 0, , 0, , 0, 0, 0, 0,


132 hours is just off Cape Canaveral.
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Computer models: GFS 18Z gives Irene the Stall of Doom over Haiti, while HWRF 12Z insinuates a cat. 3 landfall over Miami.
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Quoting JrWeathermanFL:
More polls:

What will Irene peak at?
A.50-70mph
B.75-105mph
C.110-130mph
D.135-165mph
E.170+

Will Gert emerge over the BOC?
A.Yes
B.No

What will 98L peak at?
A.Invest
B.TS
C.Hurricane
D.Major Hurricane

If we get to the Greek names, how far do you think we'll get?
A.1st name-4th name
B.5th name or more

CB(Gert already dissipated)CA
Member Since: November 13, 2009 Posts: 2 Comments: 728
Quoting CarolinaHurricanes87:
Levi and p451:

I've noticed both of u mention u think the LLC will jump / merge slightly northwards/NE into the convection and MLC at some point.... Does that mean u think the models will shift slightly to the N/E as well?


They would probably have to shift at least slightly if a reformation occurs. There is no guarantee that it will, but it may if the convection continues to fire strongly north of the surface center.
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About

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