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.

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Long-range radar out of Puerto Rico

Jeff Masters

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2673. luigi18
Quoting Levi32:


Why on Earth would NC be out of the woods. It takes only 1.5 degrees longitude to get from the Florida coast to the NC coast. That's why the whole area from south Florida to North Carolina should be watching this closely. Anyone there could see this storm.


Hello Levi you think we are going to have a category 1 hurricane here in PR or still TS ?
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This radar called Grlevelx has a station in Puerto Rico, completely forgot about that.

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2671. Dakster
Quoting USAFwxguy:


This is why they need Ausprey HH.


I don't think I would want to be on one of those in a TS either... I think it is spelled Osprey?
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Levi...#2647
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2668. HCW
Check out this ship report from the middle of Irene

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Quoting Dakster:
I am surprised that Irene isn't making a bee line for Washington, with all that hot air been blown around there... Has to be a hurricane's dream.
Ha - we could use a good house cleaning up there!
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Quoting USAFwxguy:


This is why they need Ausprey HH.


The Aussies have them too?
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Harvey could be a TS again, crazy...
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Quoting Levi32:


Why on Earth would NC be out of the woods. It takes only 1.5 degrees longitude to get from the Florida coast to the NC coast. That's why the whole area from south Florida to North Carolina should be watching this closely. Anyone there could see this storm.
Or all of them....lol
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Landfall In St. Croix?
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nam looks about right to me beaten up but still a big system north of cuba 84 hr
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Irene will be a storm running on a track which small changes in track could largely change the landfall position. If it largely misses or is otherwise not impacted by Hispaniola, this could be a very strong storm given the conditions. Very dangerous.
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Quoting NICycloneChaser:


Take off scheduled for 7:00pm EDT.
When They gonna get there? oh, right 7:05. LOL
Member Since: August 18, 2011 Posts: 0 Comments: 994
2658. Levi32
Quoting wxhatt:
Levi, Does this mean N.C. is out of the woods now?


Why on Earth would NC be out of the woods. It takes only 1.5 degrees longitude to get from the Florida coast to the NC coast. That's why the whole area from south Florida to North Carolina should be watching this closely. Anyone there could see this storm.
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2657. Dakster
I am surprised that Irene isn't making a bee line for Washington, with all that hot air been blown around there... Has to be a hurricane's dream.
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2655. WxLogic
Quoting Stormchaser2007:


Non-tropical NAM.


I knew someone was going to say something. Please note that I'm not talking about directly about Irene. NAM is used for CONUS and as we know the the C CONUS High is in CONUS and the possible cut-off low is in CONUS too.
Member Since: August 14, 2008 Posts: 4 Comments: 5038
Irene has alot more moisture than Don did. LOL. Saw Video of Puerto Rico, pretty darn wet there with a Hurricane Warning in place.
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Quoting MississippiWx:


LOL. I was hoping everyone had forgot about that by now. It still cracks me up...


Oh, you'll be hearing it for at least the next week :P
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Quoting NICycloneChaser:


A spinning propeller would not function at all well with strong winds.
Oh.
Member Since: August 18, 2011 Posts: 0 Comments: 994
Quoting 7544:
irene looks like a cat 1 hurricane at this hour whens the next plane tia


Take off scheduled for 7:00pm EDT.
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I told ya'll yesterday that Harvey would go to the BOC. Ya'll said it wouldn't and it wasn't even in the forecast track. Well lookey there. It did!
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2649. Torgen
Quoting interstatelover7165:
Why not?



Because all it would take is one wind gust to totally lose lift on one side and you'd drop like a rock, smashing to pieces with no chance to recover.

Not to mention what debris does to rotor blades...
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Quoting stormpetrol:
I think Irene will surprise a few and move south of PR and just skim the coast of DR/Haiti to the south. Next few hours should be interesting. JMO.


I think you may be right. As a matter of fact I dont see a WNW movement. Maybe slightly N of due west.
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Levi...I just saw your tropical tidbit.(very informative BTW) I saw how you showed the high's (bridging). Why wouldn't that shift the storm westward? Sorry in advance if that's a dumb question...just trying to learn!!
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Quoting 954FtLCane:

or pompano/delray.....
Let's hope it keeps moving east!
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Quoting interstatelover7165:
Why not?


A spinning propeller would not function at all well with strong winds.
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Quoting WeatherNerdPR:

Windsh*t! LOL
Still remember


LOL. I was hoping everyone had forgot about that by now. It still cracks me up...
Member Since: July 15, 2006 Posts: 17 Comments: 10284
2643. Seastep
.
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Quoting wolftribe2009:


This to me it an example of "storms" having their own mind. Anytime they sense a chance to get back over water they do so. It was why I kept saying that Harvey would emerge over the BOC. Now the chance to become a hurricane is gone because he stayed too far to the south but it might be interesting if he pulls a trick.

IMAGINE IF HE TURNS NORTH LOL

The entire blog would go crazy.


Nah. He won't Texas is suicide to anything with rain in it.
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2641. 7544
irene looks like a cat 1 hurricane at this hour whens the next plane tia
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I know we are focused on Irene and all, but we may see Tropical Storm Harvey again.

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Quoting lottotexas:
Anyone seen Miami Hurricane today?
He was on this morning when recon was out.
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2638. wxhatt
Levi, Does this mean N.C. is out of the woods now?
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Quoting Stormchaser2007:
FULL


Cool Image.
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Quoting NICycloneChaser:


Just fly straight upwards...

Helicopter would be more convenient. Though, actually, a helicopter in a TS probably isn't the best idea.
Why not?
Member Since: August 18, 2011 Posts: 0 Comments: 994
2635. ncstorm
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Quoting WxLogic:
18Z @84HR 500MB:

Interesting... cut-off low, such a solution could weaken the steering for Irene.







Yeah, the NAM is pretty crazy this run...

Member Since: July 15, 2006 Posts: 17 Comments: 10284
take your pick

Wilmington NC

Charleston SC

or the Gulf of Mexico

Those are the track that the models are giving right now in the latest runs

Link
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Quoting NCHurricane2009:


Dude...me and you must have been riding out Fran real close...when I said Raleigh...I mean southern Cary...toward the Apex side....


I live in Wilmington now... But lived in Cary for 8 years earlier. Small world lol
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FULL

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Quoting Bretts9112:

IT IS
IMPORTANT NOT TO FOCUS ON THE EXACT FORECAST TRACK...ESPECIALLY AT
DAYS 4 TO 5 SINCE THE MOST RECENT 5-YEAR AVERAGE ERRORS AT THOSE
FORECAST TIMES ARE 200 AND 250 MILES RESPECTIVELY.


I totally agree. As long as landfall in FL is possible, NHC probably doesn't want to make major changes in projected track that take FL out of play.

A 200 mile difference in position means that it could hit Miami (sooner than later). If it's headed for the Carolinas, landfall will be days later - with more time to prepare.

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2627. Torgen
Quoting interstatelover7165:
Considering that the HH are in St Croix, it certainly won't take them long to get to Irene.


But it's gonna be fun trying to get to altitude in that. Usually you can get up to where you need to be for readings without fighting every foot.
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Very much in agreement with the NHC track.
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Quoting WxLogic:
18Z @84HR 500MB:

Interesting... cut-off low, such a solution could weaken the steering for Irene.







Non-tropical NAM.
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Quoting stormpetrol:
I think Irene will surprise a few and move south of PR and just skim the coast of DR/Haiti to the south. Next few hours should be interesting. JMO.


DR/Haiti to the south??? I'd say north if anything.
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Quoting interstatelover7165:
Considering that the HH are in St Croix, it certainly won't take them long to get to Irene.


Just fly straight upwards...

Helicopter would be more convenient. Though, actually, a helicopter in a TS probably isn't the best idea.
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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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