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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in between haiti and eastern cuba at 66 hrs.

Member Since: Posts: Comments:
Quoting chsstormgirl:
Surprised the forecast from the psychic twins hasn't been mentioned tonigh regarding Irene.... Has the consensus changed to a storm later this year? Or is this still the one to wipe out the entire east coast?

:)


Hmm, thanks for the reminder. I have to schedule my reading and foot massage.
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She's going to have to have a large jump north to hit PR directly. That just doesn't seem likely. PR is going to be on the bad side though.

Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting presslord:


That pretty much reflects the reality for the majority of the folks in Haiti.
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1517. Patrap
IR Unenhanced Image


Member Since: July 3, 2005 Posts: 426 Comments: 128871
1516. Skyepony (Mod)
Windsat missed...It's messed up though. Look at it's pass of the Caribbean.. click pic & see the bottom of those two last swaths that end south of South America. Same mess up in those areas too.
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66 hours west jogging westward towards Jamaica
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still 1000 mb at 66 hours out. Between Haiti and Cuba.
Member Since: August 1, 2011 Posts: 28 Comments: 8032
1513. scott39
Everyone should do thier best to stay calm before a hurricane approaches. Get away from beaches and low lying areas. If your in a brick or solid built house you will be fine. Stay away from windows and have all the family close together. If you are in a Mobile Home or older home, you need to go to a shelter...DONT WAIT... If the eye passes directly over you..DO NOT...go outside thinking it is over! The backside of the eye will be passing very soon and the winds will pick back up. Once its over, the power will be out, you will be hot and there will be a big mess to clean up. Everyone will be fine-- Fun Fun Fun... Sarcasm Flag way up on the Fun!!
Member Since: June 13, 2009 Posts: 0 Comments: 6871
Quoting tropicfreak:


They have to put up with it constantly with every tropical system taz, most recently with Emily.



this is going too be way stronger then Emily.
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1510. angiest
Quoting trHUrrIXC5MMX:


How about another one like Ike, it was a cat 2 but very serious



It put upwards of 30 feet of surge into parts of Galveston Bay (narrower sections formed by rivers entering the bay, generally), which is in the range of a 4-5 following a similar track.
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1509. bwat
Quoting CanesfanatUT:


I like lamp.
Do you really love the lamp or are you just saying things outloud you see in the office? :) Sorry, I love that movie enough to brink me out of lurking. Ok, I need everyone to be quite, I have an urgent news update.....CANNONBALL! :) Thanks for indulging me.
Member Since: August 18, 2009 Posts: 0 Comments: 353
Member Since: August 31, 2009 Posts: 0 Comments: 5628

60 hours out brief landfall/ land interaction on the western tip of the south thing that sticks out of haiti
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i have doomcasted this storm the death so far now that the center appears to be relocting into the convection andd is becoming stacked i may have to rethink remmember s strong storm mave inch farther north and eastard
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Quoting P451:
Storm placement on the map is likely the 0z (4 hours old). But the rest is recent data.


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Quoting Mucinex:

I also lost a car. Hence the reason I refuse to forgive Max Mayfield for not putting up the Hurricane Warning till after Irene had passed the county line. Car was pretty water tight though. I pushed it 1 1/4 miles which wasn't that hard because it was floating soo well.


The NHC is the only ones that put up hurricane warnings.
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I can't see a thing, DFWstormwatch.

Link

This is more zoom in models. Just saying.
Member Since: August 1, 2011 Posts: 28 Comments: 8032
1501. Grothar
Quoting iahishome:


Hmmm, I think I'd write hrummph Grothar... I think that says 'kids, hump!' which I can't condone!


Sorry, I used the German expression. I did not know that the connotation could be misinterpreted as such. I should have just written hmmmmm! Unless there is another nuance of the language which I may have inadvertently overlooked. Please feel to correct me if the idiomatic expressions are incorrect.
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Quoting Grothar:


Thanks a heap, Orca. You guys should go back to thispst #1358 and enlarge it and see what Orca did with my name. Geez, some buddy you are. :)


hey... I just post them... its the models that run them :)

Thats where you live, its the model that put the Cat 4 in your yard
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Quoting Tazmanian:



well that would be some good new it would be overe water but they still would have too put up with flooding rains


They have to put up with it constantly with every tropical system taz, most recently with Emily.
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1498. JLPR2
Quoting Tropicsweatherpr:


To correct the latitude, PR is at 18N.


To be more precise, Ponce is actually at 17.98°N 66.6°W

The 18N line crosses PR a little below the middle(W to E).
Member Since: September 4, 2007 Posts: 7 Comments: 8735
Quoting prweatherwatcher:



Actualy PR is betwen 18.0 and 18.6 N & 66.0 and 67.7W.


Yes, I am aware now...thanks to the 5 other posts about it.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting MississippiWx:


PR is up at 19N and the center should be no farther north than 16N. That would be a huge jump north...
PR is @ 18.6.. i think this will hit us..in P.R
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Hey guys what do you to take from the fact that the global models show Irene running into a good amount of land interaction and they are still blowing this up to a major hurricane?
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Surprised the forecast from the psychic twins hasn't been mentioned tonigh regarding Irene.... Has the consensus changed to a storm later this year? Or is this still the one to wipe out the entire east coast?

:)
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Quoting dfwstormwatch:

57 hours out c.o.c passes southwest of port-Au-prince,Haiti



well that would be some good new it would be overe water but they still would have too put up with flooding rains
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Quoting MississippiWx:


PR is up at 19N and the center should be no farther north than 16N. That would be a huge jump north...



Actualy PR is betwen 18.0 and 18.6 N & 66.0 and 67.7W.
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wow at 54 hrs out...
Member Since: August 1, 2011 Posts: 28 Comments: 8032
Quoting Tropicsweatherpr:


To correct the latitude, PR is at 18N.


PR is most likely going to get a lot of rain and some wind, but the center won't hit directly. The steering is too straight forward the first 48 hours. We'll see.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
This track reminds of Charley......which hit me hard in Port Charlotte.
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Quoting dfwstormwatch:
i am



i hop this move a way and dont hit tent city
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Quoting MississippiWx:


PR is up at 19N and the center should be no farther north than 16N. That would be a huge jump north...


For the short term....I am seeing something like the NOGAPS line in Chicklit's post (post 1461)....or the black X position in the 700 mb vort map on the post beell made....

That NOGAPS line is best what I am trying to say for the short term....
Member Since: September 15, 2009 Posts: 504 Comments: 3688

57 hours out c.o.c passes southwest of port-Au-prince,Haiti
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Quoting presslord:





this is not good
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1483. Patrap
Creepy Dvorak


Member Since: July 3, 2005 Posts: 426 Comments: 128871
1482. Gorty
Quoting AussieStorm:

Up to you but it looks like a repeat Danielle from last year.



Yep, except this one is further east and north. And that is a very large area of disturbed weather, interesting to see if any will split off and try to form something or if it will all come together and form into one super big cyclone.
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Quoting Grothar:


Even though I live on and Island on the Intracoastal in Ft. Lauderdale. We only have to evacuate for 4's & 5s' There are maps which will tell you. Then do recommend that we do but not necessary.


How about another one like Ike, it was a cat 2 but very serious
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Quoting MiamiHurricanes09:
Am I the only one that sees the circulation under the convection to the WSW of Antigua?

no, i see it too. i also have a question that no one can seem to answer. care to give it a shot?
gom- 23n 87w. do you see that? look on unenhanced check out the spin going on.
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Quoting Tazmanian:
some one post a mode run
i am
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Quoting MississippiWx:


PR is up at 19N and the center should be no farther north than 16N. That would be a huge jump north...


To correct the latitude, PR is at 18N.
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Quoting cat5hurricane:

I know exactly what you were referring to. Give it a rest.

You brought it up. Go ahead, explain it to me.
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Quoting lucreto:


That was based on a bogus run with erroneous data once that was corrected I was spot on.


you are only spot on in your own mind

to the rest of us, well......
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Quoting Tazmanian:



your telling me they have like 700,000 still in tent city i think


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1473. JLPR2
Quoting MississippiWx:


PR is up at 19N and the center should be no farther north than 16N. That would be a huge jump north...


PR is at 18N and the NHC says:
24H 22/0000Z 16.6N 65.9W 55 KT 65 MPH
Member Since: September 4, 2007 Posts: 7 Comments: 8735
some one post a mode run
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Quoting chsstormgirl:


That's correct, he was declared the official poster last night!!
As a matter of fact, he was appointed the official poster, about this time last night. And it was duly noted as such.
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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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