Dangerous Tropical Storm Irene headed for the Dominican Republic

By: Dr. Jeff Masters , 2:38 PM GMT on August 21, 2011

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Tropical Storm Irene roared into life last night, transitioning from a tropical wave to a 50 mph tropical storm in just a few short hours. Irene is getting organized quickly, and has the potential to become a hurricane by Monday morning. All interests in the Dominican Republic, Haiti, Cuba, the Bahamas, and South Florida should prepare for the arrival of this dangerous storm. An Air Force hurricane hunter aircraft in the storm found the strongest winds near 18°N latitude to the north of Irene's center at 8am this morning. After passing through the center, the plane returned to the area of strongest winds two hours later, and found that flight level winds at 5,000 feet had increased by about 5 - 8 mph. However, the pressure in the latest center fix taken at 10am EDT remained the same as two hours previously, 1007 mb, and the plane noted that Irene's center was not circular, signs that the storm still has some work to do before serious intensification can begin. Visible satellite loops and radar out of Martinique show the storm has rapidly organized this morning, with well-developed spiral bands forming and a large area of intense thunderstorms to the north of the center. Irene has shrugged off the dry air that was bothering it yesterday, and wind shear has fallen to the low range, 5 - 10 knots, as analyzed by the University of Wisconsin CIMSS group. Torrential rains and strong gusty winds are affecting the northern Lesser Antilles this morning. A wind gust of 41 mph was recorded at St. Eustatius at 8am local time.


Figure 1. Morning satellite image of Irene.

Track forecast for Irene
The computer models are in agreement that Irene will pass just south of Puerto Rico tonight, then hit the south coast of Hispaniola in the Dominican Republic or Haiti on Monday afternoon. Irene should then emerge into the channel between Haiti and Cuba on Tuesday afternoon, when the storm will have 12 or so hours over water before having to contend with Cuba. A trough of low pressure is expected to move across the Eastern U.S. on Wednesday and Thursday, turning Irene to the northwest and north by Thursday. The 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. Irene's strength will also matter--a stronger Irene is more likely to turn northward earlier. The most likely path for Irene is a track just east of the Florida Peninsula and into Georgia, South Carolina, or North Carolina by next weekend, but a landfall near Miami then directly up the Florida Peninsula is also a reasonable solution--like Tropical Storm Fay of 2008 did. 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.

Intensity forecast for Irene
Irene is embedded in a large envelope of moisture now, and wind shear will remain low, 5 - 10 knots, for the next five days. With water temperatures very warm, 28 - 30°C, these conditions should allow for intensification except when land is interfering. Irene's current appearance on satellite loops gives me the impression of a storm that is not fooling around, and I expect Irene will be a hurricane before hitting Hispaniola on Monday. Passage over Hispaniola will not destroy Irene, since it is a fairly large storm. Once the storm finishes with Hispaniola, it will have to deal with Cuba, which will keep Irene from intensifying significantly. Once Irene pops off the coast of Cuba Wednesday or Thursday into the Florida Straits, Irene will likely be a tropical storm. If the storm then has at least a day over water before hitting land, it will likely become a hurricane again, and could become a major hurricane if it ends up missing South Florida and moving over the warm waters on either side of the Florida Peninsula.

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 southern Mexico, but dissipation is expected tonight 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.

Invest 98L northwest of the Cape Verde Islands
A tropical wave few hundred miles northwest of the Cape Verde Islands off the coast of Africa, Invest 98L, has become disorganized and lost most of its heavy thunderstorms. The disturbance is moving over colder waters and encountering drier air, and NHC is giving 98L only a 10% chance of developing into a tropical depression by Tuesday. The latest set of model runs keep 98L well out to sea away from any land areas over the next five days.

Links
Long-range radar out of Puerto Rico

Jeff Masters

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Quoting WeafhermanNimmy:
Guys where are some good places to hurricane chase if it makes landfall in SC?


tie yourself to the Folly Beach pier...
Member Since: August 13, 2007 Posts: 0 Comments: 10484
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Quoting WeafhermanNimmy:
Guys where are some good places to hurricane chase if it makes landfall in SC?


From the hotel tv in Columbia...you don't want to chase this one.
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Quoting WxLogic:


Will be on late too then :). Do you have happen to have the flight pattern by any chance?


Flight pattern not posted yet.

Final 06Z HWRF position





HOUR: 126.0 LONG: -79.20 LAT: 32.10 MIN PRESS (hPa): 933.00 MAX SURF WIND (KNOTS): 100.00
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I dont like the 6z gfs it brings the center almost right over me while its still at hurricane with 984mb pressures yikes :/
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75 mph on the NHC website---until 8am at least
Quoting JrWeathermanFL:
Wikiapedia said Irene is 85mph. Is this true?
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Quoting weathermanwannabe:
Good Morning. I am leaving for CT today to take supplies to my Daughter in College in the pick-up. Gonna miss you folks and let's pray that Florida and as much of the US as possible stays on the weaker west side of the storm. The Bahamas needs to prepare for a Cat 2-3 because it will really ramp up for them.

If the storm does make landfall on the East Coast, I will be driving back to Florida on Friday so I may take I-85 or I-75 down instead of I-95.

Talk to you folks during the weekend.........WW
safe trip take alot of cds
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Quoting JrWeathermanFL:
Wikiapedia said Irene is 85mph. Is this true?


No, still at 75mph.
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Good morning irene, let me pour you a cup of coffee, so you can wake up and increase in cycling endurance..

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Quoting doabarrelroll:


At this point parts of this bog become useless. People here from Florida will still say "its coming to Florida" people here from SC and NC will say "its coming to the Carolinas" and GOM airea blogger will say "OMG u guys if this gets into the GOM it could be really bad". For now I will trust the NHC until I am out of the cone.
if the blog is usless why are you
here?
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POLL TIME!

What will be Irene be at 8?
A.80 mph(CAT1)
B.95 mph(CAT2)
C.115 mph(CAT3)
D.135 mph(CAT4
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vis. giant mass of clouds
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Guys where are some good places to hurricane chase if it makes landfall in SC?
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Good Morning. I am leaving for CT today to take supplies to my Daughter in College in the pick-up. Gonna miss you folks and let's pray that Florida and as much of the US as possible stays on the weaker west side of the storm. The Bahamas needs to prepare for a Cat 2-3 because it will really ramp up for them.

If the storm does make landfall on the East Coast, I will be driving back to Florida on Friday so I may take I-85 or I-75 down instead of I-95.

Talk to you folks during the weekend.........WW
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Wikiapedia said Irene is 85mph. Is this true?
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Quoting doabarrelroll:


At this point parts of this bog become useless. People here from Florida will still say "its coming to Florida" people here from SC and NC will say "its coming to the Carolinas" and GOM area blogger will say "OMG u guys if this gets into the GOM it could be really bad". For now I will trust the NHC until I am out of the cone.


That's a good idea. Their tracks are very accurate, and if they need to adjust again they will. They know what they're doin.
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7104. WxLogic
Quoting nrtiwlnvragn:


No flight last night, first one this afternoon.


Will be on late too then :). Do you have happen to have the flight pattern by any chance?
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Quoting Waltanater:
We always have to be concerned with the "worst case scenario" in these situations. Now we have been told by models and general consensus that the storm is taking a more eastern route (east side of FL), however is there a possibility that it will keep wnw and therefore hit SFL directly? If so, what is the one PRIMARY factor here that "could" cause this westerly component and how strong a factor is that now, or will be? Anyone's thoughts about this.


I don't know whether a WNW orientation is possible. A S-N orientation is possible if the high to the E were to build in more, of if the storm stayed weaker..
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7101. A4Guy
the NHC clearly notes the following...which should be considered when relying so heavily on the Eastern outlier models:

WHAT IS NOTEWORTHY IS THAT ALL OF THE GLOBAL AND REGIONAL MODELS AGREE THAT THE OUTFLOW OF IRENE WILL CONVERGE WITH WESTERLY TO NORTHWESTERLY UPPER-LEVEL
MID-LATITUDE FLOW OVER THE MID-ATLANTIC STATES BY 96 HOURS AND BEYOND. THIS UPPER-LEVEL MASS CONFLUENCE COULD MAINTAIN THE MID- TO LOW-LEVEL RIDGE A LITTLE BIT STRONGER AND LONGER THAN WHAT NOGAPS AND THE ECMWF ARE FORECASTING...
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Quoting WxLogic:


I was meaning to ask you about that... based on your statement I take last night we didn't have any G-IV flights?


No flight last night, first one this afternoon.
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We always have to be concerned with the "worst case scenario" in these situations. Now we have been told by models and general consensus that the storm is taking a more eastern route (east side of FL), however is there a possibility that it will keep wnw and therefore hit SFL directly? If so, what is the one PRIMARY factor here that "could" cause this westerly component and how strong a factor is that now, or will be? Anyone's thoughts about this.
Member Since: May 16, 2010 Posts: 0 Comments: 1471
Quoting nash28:


Everyone should be taking this seriously. Not waiting until a hurricane watch is issued.

Everyone from FL, GA, SC and NC need to be prepared. All four states are possible here.


Interesting only bc I still feel no level of threat whatsoever in Wilmington! Not me, but the general public seems very disconcerned, or unknowing. I realize this may be due to our location being further north and Irene taking longer to get here....

but if she doesnt cross Hispanolia I see nothing stopping her from gaining strength and am worried we could quickly have a major hurricane coming our way. Guess we'll find out the next couple days, but people here seem to still be in "watch and wait" mode... if theyve even heard about Irene
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Quoting WxLogic:


For this year... good question.
gfs
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7095. nash28
06zGFS is rather ugly.

Rakes SC/NC and also appears to slow forward motion which is never good.
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Morning from Palm Beach County. Probably a good thing that school is back in session. Haven't had a chance to look at the latest model runs, but I'm assuming they are moving further and further east as they have been? TIA.
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7093. WxLogic
Quoting nrtiwlnvragn:


Think I will stay up late tonight to see the 00Z that should have the data from this afternoon's high altitude flight. If a model windshield wipe is coming, that would be the first to indicate it.


I was meaning to ask you about that... based on your statement I take last night we didn't have any G-IV flights?
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7092. Hhunter
-----This will be the strongest hurricane to hit the east coast since Floyd of 1999 and right in line with analog years used here in the preseason forecast for years with hurricanes that ran the east coast.

The path is shifted a bit further east and the hurricane is now forecasted to go to cat 4 before making landfall in the Carolinas, cutting to the mouth of the Chesapeake, the striking New England as the first hurricane to make landfall there since Bob in 1991. ---from Bastardi....

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Quoting scott39:
Where is the trough coming from and when should we be able to see it on the satt?


There's 2. You can see #1 over the NE US on WV imagery of the Eastern United States.
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Oh my, now all you people talking OTS with Irene are going out on a limb. All you will do is bring out all the fish trolls to the blog
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Quoting WxLogic:


Won't be surprised that it goes out to sea like NGP.


Think I will stay up late tonight to see the 00Z that should have the data from this afternoon's high altitude flight. If a model windshield wipe is coming, that would be the first to indicate it.
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Quoting CanesfanatUT:


XTRAP

haha


LOL
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7087. scott39
Where is the trough coming from and when should we be able to see it on the satt?
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Quoting CarolinaHurricanes87:
When will the forecast be considered accurate enough (and Irene close enough) to start issuing watches and warnings for the US?

And when should people here in Wilmington, NC start taking this thing seriously? (not as far as following the storm, but getting ready for it?)


NHC issues watches 36-48 hrs before, and warnings 24 hours before. When you're in the 3 day cone you should be starting final preps..
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7085. WxLogic
Quoting FSUstormnut:
which model has done the best this year?


For this year... good question.
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Quoting WxLogic:


Won't be surprised that it goes out to sea like NGP.


this looks like another emily track, just east of florida..coincidence..hmmm more like current storm pattern.
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7083. nash28
Quoting CarolinaHurricanes87:
When will the forecast be considered accurate enough (and Irene close enough) to start issuing watches and warnings for the US?

And when should people here in Wilmington, NC start taking this thing seriously? (not as far as following the storm, but getting ready for it?)


Everyone should be taking this seriously. Not waiting until a hurricane watch is issued.

Everyone from FL, GA, SC and NC need to be prepared. All four states are possible here.
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Quoting FSUstormnut:
which model has done the best this year?


XTRAP

haha
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Quoting nash28:
Having a hurricane prep meeting this morning at work. Most of the folks I work with have never been through a hurricane before..
That should be fun...
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"Pumping the ridge" does not exist! Y'all stop it!!!

Off to class; see y'all later. Got to go learn me how to fix some radars...Well, I think we'll start with basic electronics until next term.
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which model has done the best this year?
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7078. scott39
Quoting WxLogic:


Won't be surprised that it goes out to sea like NGP.
I hope your right!
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When will the forecast be considered accurate enough (and Irene close enough) to start issuing watches and warnings for the US?

And when should people here in Wilmington, NC start taking this thing seriously? (not as far as following the storm, but getting ready for it?)
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Quoting nrtiwlnvragn:
06Z HWRF so far trending further east.


this is what my money is on... NC, maybe Cape hatteras. gonna be a monster storm but its more and more North and East of forecast points. too late for the Bahamas though
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7074. WxLogic
Quoting nrtiwlnvragn:
06Z HWRF so far trending further east.


Won't be surprised that it goes out to sea like NGP.
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Wow, 6Z GFS pushed a lot East. I know can't put any faith in one model run, but this has been a trend. Is the strengthening of Irene faster than anticipated, plus the lower anticipated land interaction causing this? I am also reading that the high is anticipated to be STRONGER, how does this jive with the further east tracks?
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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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