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 NCHurricane2009:


Is that a 51 kt wind at surface or flight level?


Flight level, estimate surface winds:

43.1 knots (~ 49.6 mph)
Tropical Storm
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770. Skyepony (Mod)
FNMOC Navy has Harvey in the EPAC.
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Models are gonna shift left, right, about 20 times from now till Thursday. Remember that 5 day forecast are subject to large errors.
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I think HH just entered an area of higher winds last barb is showing 50 knots, we will see if it gets any higher, 55 or 60 knts.
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How close to the coast is the dry air? And are you talking about the carolinas or florida? If the storm stayed 50 miles offshore and parallelled the coast, couldn't it stay at a cat 2, 3, or 4 strength all the way up to Georgia?

Was there ever a major hurricane that ran up the entire FL coast without touching it?

Quoting sullivanweather:
Believe it or not, a storm stalling over the Gulf Stream off the coast would tend to weaken it. There's plenty of dry air over towards the Southern Appalachians in all the model runs by the time the storm gets there so it would be likely that the storm would ingest this dry continental air being stalled so close to the US mainland.

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Quoting presslord:
A direct hit on Hilton Head would wipe out half the population of Canada!!!


LOL! There are more Ontario license plates on Hilton Head than mosquitoes!
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Irene still dealing with dry air issues; satellite imagery shows outflow boundaries from collapsing thunderstorms. In addition, the low level center displaced to the south of the mid level center within a cyclonically curved band.
Member Since: October 28, 2006 Posts: 57 Comments: 30490
Quoting SavannahStorm:
Recon found 51kts 100 miles north of the center-

Irene is a big girl, need to go on Atkins.

From 100° at 51 knots
(From the E at ~ 58.6 mph)


Is that a 51 kt wind at surface or flight level?
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Quoting cloudburst2011:
im very glad to say this with confidence the strong high over texas isnt going anywhere until next saturday so that should assure the central and eastern GOM the protection from irene...so we here have nothing to worry about just pray for our friends in florida and hope they fair out well with irene...
Very true, Irene does not look to get too strong right now which is a good thing also.
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Well i see Irene is having some stomach problems after she ingested that dry air last night, she is likely going to get you PR, Sorry, pretty unexpected, But BE PREPARED, looks like PR, then Scrape NE DR before heading into the VERY EXCEPTIONALLY WARM WATERS in the turks and caicos/Bahamas and GULF STREAM, should be interesting for sure
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760. Skyepony (Mod)
Oceansat of 98L
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Quoting scottsvb:
Chances of Irene.

Bahamas 60%
Stay east of Bahamas 20%
Florida 15%
Gulf of Mexico 5%

Puerto Rico 99%
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758. swfla
It appears to be coming though
Link

Quoting weathercuco:
report from Sabana Grande, PR: winds are picking up a bit, getting really cloudy. no rain yet.
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Quoting TropicalAnalystwx13:
Irene is beginning to strengthen, and has that hurricane look...75 mph cane in 24 hours or less IMO.



Very ominous. Be ready PR!
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717. shawn26
Can someone post the latest GFDL?


been tring too, be here is the latest models link..for some reason can't upload the pic?? Link
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A direct hit on Hilton Head would wipe out half the population of Canada!!!
Member Since: August 13, 2007 Posts: 0 Comments: 10490
Chances of Irene.

Bahamas 60%
Stay east of Bahamas 20%
Florida 15%
Gulf of Mexico 5%
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Quoting 7544:
its one run peeps wait for the next one models are getting confuse right now stay tuned


What's to get confused. All the models have shifted EAST!
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Quoting Joshfsu123:
We are still more than 5 days out from a potential landfall on Thursday/Friday (if it hits Florida).

Models are often WRONG by up to 200/250 miles this far out in time and the NHC often cites this in their discussion when they issue their forecast path out 5 days.

Yes, storm may go to NC - it may go to Florida and if it stays weaker due to land interaction, it could make it into the eastern Gulf of Mexico.

It comes down to timing and right now, its going to be close.... but ONE model run doesn't mean it is going anywhere... you need to look for consistency and wait for all the computer models to come into better agreement, which right now there are some differences.


Right on...and I don't think we can favor one scenario (E GOM) or the other (east US coast) until we see how Irene passes Hispaniola....this will be the critical time....
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Quoting wxhatt:


Yes! Definitely!


Someones excited...
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Quoting connie1976:
...so....I'm confused....South Florida is now out of it? Why does the nhc still have us in the cone then? will they change it at 5?

Connie this called watching every model run hysteria. The NHC can't change its cone every hour when the GFS comes out, and then 2 hours later because of the ECMWF swings East or West. Look for trends and a consensus. South Florida is not out of it go by what the NHC cone shows you not a model run, if Irene's path changes the cone will adjust in time.
Member Since: July 7, 2005 Posts: 0 Comments: 5306
Quoting TropicalAnalystwx13:
Irene is beginning to strengthen, and has that hurricane look...75 mph cane in 24 hours or less IMO.


I see an arc cloud.
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People- THIS DOESN'T MEAN FLORIDA IS OUT OF IT. Models always shifts so it's still to early. People from Tampa to Virginia Beach need to watch this CAREFULLY.
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Quoting connie1976:
...so....I'm confused....South Florida is now out of it? Why does the nhc still have us in the cone then? will they change it at 5?
Umm, South Florida is NOT out of it...yet. (And may not be "out of it", concerning Irene's ultimate track.)

*Could* still get TS force or hurricane force winds out of Irene with a close enough track even if it doesn't get a direct landfall, which is also still possible.

Would it be useful and sensible if they jumped on a S FL miss only to call for a hit in the next advisory?
This is, and always will be, a dynamic process with lots of moving parts that sometimes behave in ways not predicted.
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Irene is beginning to strengthen, and has that hurricane look...75 mph cane in 24 hours or less IMO.

Member Since: July 6, 2010 Posts: 113 Comments: 32029
I don't know who's worse... those saying it's going to directly hit Florida, or those who now say it's going to ride the coast and hit SC.

Calm down guys! LOL
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Quoting cloudburst2011:



well imo this is already mapped out irene with everything set in place cant miss fla...the high to the east is building in combined with the 2 trofs later in the week will put irene right on top of fla...this cone will not deviate its solid...
i am seeing what you are saying but history tells me the cone will shift. Whether it is east west north or south i have no idea. i just know the 5 day error for the cone is large thus the cone will move.
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really dark now in St. Barth's
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Quoting chevycanes:

it's crazy how you now have people saying FL is not at risk now and that the cone will shift way east.

this is 1 model run of the GFS. let's see what the Euro, GFDL, HWRF and others show. even then it's just too early to tell.


Not true.. GFS does well out to 5 days. Your right that we still need to see the Euro..but that has also trended east from 12Z yesterday.
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6z GFDL
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Quoting TaylorSelseth:
I think Irene will barely miss Hispanola, which is BAD NEWS for the Carolinas. :-(


Yes! Definitely!
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Quoting Patrap:
12z Early Cycle NHC model tracks
Irene
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Heya PATRAP, that one statistical track goes over your house!! Least it isn't a dynamic track LOL
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untill they find other readings this is what they will stick by at the 2.

1007mb (29.74 inHg)
Sea Level (Surface) 120° (from the ESE) 44 knots (51 mph)
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Quoting CCSoFLA79:


Thank you for the response. I seem to think the same. I will begin preps making sure my supplies are ready Just incase. Thank you again



dont get me wrong the c0ne will shift SLIGHTY east south florida will still be in the center lets see a few consistent models runs showing it missing fl then ill talk
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Recon found 51kts 100 miles north of the center-

Irene is a big girl, need to go on Atkins.

From 100° at 51 knots
(From the E at ~ 58.6 mph)
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Quoting TaylorSelseth:
That's exactly why I don't want this to hit Hispanola. I find it very sick to see people WANTING it to hit the island to disrupt the storm. It smacks of "they are not white people, so who cares what happens to them".


yes...there is a lot of thinly veiled racism afoot when it comes to Haiti
Member Since: August 13, 2007 Posts: 0 Comments: 10490
NHC has Florida in the cone for now.. but it will adjust to the bahamas. Florida isnt 100% not going to be hit.. but chances are like 20% only.

I wouldnt be suprised to see this go even more East than the 12Z GFS run Long range 5day outlook showing a threat to Carolinas.. but it's too far out to say yet.
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day time model runs are East nite times are west as of right now there is no WNW monement
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Quoting Hurricanes12:
Everyone is freaking about one model shift, LOL.


it's crazy how you now have people saying FL is not at risk now and that the cone will shift way east.

this is 1 model run of the GFS. let's see what the Euro, GFDL, HWRF and others show. even then it's just too early to tell.
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Quoting Grandpato4:


Hugo?
Not as strong, but yea it landfalled between Savannah, Ga and Charleston, SC as Category 1/2
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727. 7544
Quoting Hurricanes12:
Everyone is freaking about one model shift, LOL.


thats too funny
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Quoting weatherman12345:
hahahaha
WHAT?
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Crappy quality, but here is Irene's center on PR long range radar.
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Miami, Jacksonville, Hilton Head, Savanna,
Member Since: August 27, 2005 Posts: 0 Comments: 685
May have a three-some:

Member Since: July 6, 2010 Posts: 113 Comments: 32029

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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.