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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Good Morning. Lots of the folks on the Blog certainly follow the models and NHC bases their track on the model guidance as well. While we can certainly speculate as to where the models will shift to based upon emerging conditions, best thing to do IMHO (certainly for the general public) is to focus on the NHC 3-Day track which is the best educated guess out there. Also, since this is such a large storm, it will have far reaching impacts so do not focus on the center line but prepare accordingly if you are in the 3-day cone just in case.
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Wow, couple of model runs and now some are saying Florida is out of it?? Wishcasting to NC, GA, SC etc... unbelievable. It is still too early to tell what it will really do but doesn't appear the cone has moved as of yet. JMO
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Quoting wxhatt:
Look at this, gaining lattitude all the time. On this trajectory, it may even get on the north side of PR.

This is what the models are seeing. I expect a shift even farther to the east...


not to me looks like it on a west course s of puerto rico
Member Since: September 11, 2010 Posts: 1 Comments: 5001
For now GFS is pretty much in line with HWRF and ECMWF.

We'll see how it ECMWF does on the 12Z run.
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819. 7544
what time does the euro come out next ?tia
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Look at this, gaining lattitude all the time. On this trajectory, it may even get on the north side of PR.

This is what the models are seeing. I expect a shift even farther to the east...


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Storm Relative 1km Geostationary Visible Imagery


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Irene will never become a hurricane unless it gets some deep convection near the center. Which does not look to be happening anytime soon! If it remains 50mph with a small circulation, will not even survive hispaniola (see: Emily). Not RIP-casting, just being realistic. Everyone needs to stop looking at the models 200 hours out to see where it will make landfall (highly inaccurate that far out), and keep in mind that it might not make it that far.

Also, I'm seeing a more westerly motion for the first time since advisories started being issued (Even though NHC keeps saying it's moving due west when it's obviously been constantly gaining latitude).
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Quoting 7544:
is she getting stronger at this hour ?


IMO...not until I see a convective burst in the center of the comma head due ESE of Puerto Rico....
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For now the TVCN (Consensus Model) is a SEFL strike. It has shifted slightly eastward and if the 18Z is likewise the NHC will shift the cone eastward in line with the TVCN as they are currently west of it. TVCN is highly accurate and the NHC track is NEVER too far from it, if not on it. TO avoid swinging with every shift in the models, likely to be more shifts, I personally stick with the consensus.

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Guys, we have been watcing these model runs from day 1, back and forth-back and forth. And will continue to do so at this time until we get closer to an actual track. As of now the Hurricane Center has Florida in the cone, yes that good change but all this west or further east or Ga/Sc/Nc talk, take it one day at a time until it becomes more clear. Take the precautions now just incase. But as far as track for now, keep an eye on the Hurricane Centers track.
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Quoting rkay1:
Why doesn't this blog have auto refresh or live updates?  Get with the times wunderground...


F5.....F5.....F5....lol
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Quoting TropicalAnalystwx13:


Definitely not true.


2005 Ophelia - never got over cat1 while meandering over the Gulf Stream
1999 Dennis - went from cat2 to tropical storm while stalled over the Gulf Stream
1999 Floyd - Turned and slowed over the Gulf Stream and weakened from cat 4 to cat 2
1995 Felix - Performed a very slow right turn over the Gulf Stream, only maintained strength.

The Gulf Stream hardly ever intensifies storms because of proximity to land and the typical presence of a frontal boundary in the region of the East Coast providing shearing winds. The Gulf Stream historically is only able to maintain the strength of systems encountering this more hostile environment.
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We need Levi
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Quoting WeatherNerdPR:

Puerto Rico 99%

Webcam view of the beach of San Juan, Puerto Rico.

Click image for link page.
Member Since: September 30, 2007 Posts: 9 Comments: 15977
most likely fri will be a day i remember
Member Since: September 11, 2010 Posts: 1 Comments: 5001
Looks like anywhere from FL to NC could be effected by Irene.
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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".

Oh, please, get off your high horse. The storm does not care about what we want it to do. It will do what it does. We have no control over that. It's simply a fact that if it mows through Hispaniola that could severely weaken it. No one wants anyone to suffer. (and if they do, that is their problem, won't affect the storm)
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Quoting Bluestorm5:
Oh boy... 384 hrs out, we got another tropical system. If that high pressure remains in mid-Atlantic for the next 2-3 weeks, Irene may not be the only storm to hit Florida/East Coast....
And it still likes that big monsoon low in the GoM...which hopefully, if it happens, will only be a large, disorganized wetmess for Texas, rather than a significant cane.
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802. wpb
INTERESTS IN FLORIDA ARE ADVISED NOT TO FOCUS
ON THE EXACT FORECAST TRACK BECAUSE OF THE INHERENT UNCERTAINTIES
IN LONGER-RANGE FORECASTS.

above was written into the 11am discussion
maybe so people in fla wont go nuts bc the nhc track is over them.let them know it could move hundreds of miles from what they have now...
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Look at this, gaining lattitude all the time. On this trajectory, it may even get on the north side of PR.

This is what the models are seeing. I expect a shift even farther to the east...


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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?
you need to stop reading what everybody posts here as actuality, truth and/or gospel. These are people's opinion based on model runs and minute by minute staring at the satellites. At this point, there is noting definite as to her exact track or strength. You are best off monitoring what the NHC says and once it is three days out, thats when the pieces will begin to fall into place.
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look at the big vis shot of the tropical atlantic irene is headlining now these system like that
Member Since: September 11, 2010 Posts: 1 Comments: 5001
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Quoting presslord:


yes...there is a lot of thinly veiled racism afoot when it comes to Haiti

...and sometimes not-so-thinly veiled... :-\
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Quoting Bluestorm5:
Oh boy... 384 hrs out, we got another tropical system. If that high pressure remains in mid-Atlantic for the next 2-3 weeks, Irene may not be the only storm to hit Florida/East Coast....


Dont post maps past 5 days.. they are pointless
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Quoting TropicalAnalystwx13:


I don't see any outflow boundaries, just a lot of cirrus.



Yes there are in that same image you posted. Notice the arc of clouds at the surface to the west of the mid level center, that's an outflow boundary.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
Quoting NCHurricane2009:


Dude...more like 100%...Irene's imminent for Puerto Rico IMO....

First time I've seen all of PR go blood red:
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Quoting SavannahStorm:


LOL! There are more Ontario license plates on Hilton Head than mosquitoes!


LOL...what? I never knew that....huh
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Since I'm probably 1 of 2 Mets on here right now.. if anyone has a question..feel free to ask.
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Thanks all!! :)
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12Z NOGAPS has the bahamas and heading to SC 120 hours out

Link
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Quoting TropicalAnalystwx13:
It stalled over the Gulf Stream...



That model is DOOOOOM :-(
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784. Skyepony (Mod)
Irene partial pass by ASCAT.
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Oh boy... 384 hrs out, we got another tropical system. If that high pressure remains in mid-Atlantic for the next 2-3 weeks, Irene may not be the only storm to hit Florida/East Coast....
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Quoting WeatherNerdPR:

Puerto Rico 99%


and R.D. 98.9%
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781. 7544
is she getting stronger at this hour ?
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Quoting Drakoen:
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.


I don't see any outflow boundaries, just a lot of cirrus.

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764. Drakoen


exactly, that's why my thinking is a lot more of a westerly track than what they are expecting..but just me and i'm not wishcasting either :) just seeing what i see
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Quoting WeatherNerdPR:

Puerto Rico 99%


Dude...more like 100%...Irene's imminent for Puerto Rico IMO....
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Landfall in the US is still a long way off from the POV of uncertainty. If you have time, look at the range of possibilites in the CMC ensemble run on day-5 (GFS won't be much different). MSLP runs from 938 mb to 1004, and position from Georgia to western Cuba. Link
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09L/TS/I/C0
MARK
17.65n/63.57w
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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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