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 TropicalAnalystwx13:


Take your finger and put it on the screen where the loop starts. Take another finger and put it where it ends. At that current projection, it would only clip the NE part of Puerto Rico. Right??
now there is scientific accuracy at it's finest...
Member Since: August 15, 2008 Posts: 0 Comments: 2515
Quoting NCHurricane2009:


More like +100000


You are under exaggerating.
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2471. Skyepony (Mod)
UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 21 AUG 2011 Time : 191500 UTC
Lat : 17:14:42 N Lon : 64:18:45 W


CI# /Pressure/ Vmax
3.1 / 999.4mb/ 47.0kt


Final T# Adj T# Raw T#
2.8 2.6 2.6

Center Temp : -32.7C Cloud Region Temp : -48.2C

Scene Type : CURVED BAND with 0.38 ARC in LT GRAY
Maximum CURVED BAND with 0.60 ARC in LT GRAY
at Lat: 18:02:24 N Lon: 64:54:36 W



Cloud Region Scene Type Description
UNIFORM CDO Overcast cloud region with uniform temperature structure
EMBEDDED CENTER Arc of convection within central overcast cloud region
IRREGULAR CDO Cloud region over storm center, but large shift in coverage
CURVED BAND Curved cloud region surrounding circulation center
SHEAR Displaced convection and exposed circulation center

Eye Region Scene Type Description
EYE Any eye type (clear, ragged, and obscured)
PINHOLE Very small eye/pronounced warm spot
LARGE Clear, well-defined eye with radius >= 38 km
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Quoting WxLogic:
18Z NAM @694HR:



Notice the High and TROF positions

694HRS?!
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2469. Levi32
Virgin Islands are reporting a 1003mb pressure as Irene's center nears, with 30-40kt winds out of the northeast.
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Quoting USAFwxguy:


Well it won't be a large distance... but the RADAR feature I think is tricking a bunch of people anxious to see an eye. It is close, but I think the storm CoC is a bit further south along 17.5, just beyond 64.

As seen on RGB.


What you're seeing on RGB is more mid-level. Radar is the best tool we have right now to figure out where a center is located. It's much better than any visible or infrared at this point.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting USAFwxguy:


Well it won't be a large distance... but the RADAR feature I think is tricking a bunch of people anxious to see an eye. It is close, but I think the storm CoC is a bit further south along 17.5, just beyond 64.

As seen on RGB.


Then the radar would show it..
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LOL bird on the camera.

http://www.comoestaeso.com/forums/content/inches- live-surf-cams-22/
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A question before the 5pm rush....Why is the GFDL having such a tough time with Irene? Is it predicting stronger/weaker steering?
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Quoting stormpetrol:


+1000


More like +100000
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Im seeing a wobble slightly west, may not change the heading of WNW, but its not an illusion, we wont know where shes heading untill she shows us the way.
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lol...

MississippiWx and TropicalAnalystwx13 vs. stormpetrol and USAFwxguy.

j/k
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Looks like most of the heaviest rainfall is North and East of Puerto Rico.

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2460. WxLogic
18Z NAM @69HR:



Notice the High and TROF positions
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Quoting scott39:
The way some of your are living for every model run to go your direction is embarassing! It turns WU into a joke for lurkers who are needing help.


Yes, it can be frustrating if you really need information but I always take my local authorities advice first and foremost. I've been thru probably a dozen TS's and Hurricanes in my life and your locals are the best to listen to.
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http://www.comoestaeso.com/forums/content/inches- li ve-surf-cams-22/

Puerto Rican web cam... on the SE coast.
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HWRF and GFDL show all of Florida needs to watch this closely. Just because other models are trending to east does not put anyone in FL off the hook, besides that the cone is going to keep FL on the map for most of the forecast period. Might want to get prepared.
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2453. scott39
Quoting scott39:
The way some of your are living for every model run to go your direction is embarassing! It turns WU into a joke for lurkers who are needing help.
Not to mention the dramatization of how strong it may get.
Member Since: June 13, 2009 Posts: 0 Comments: 6912
would not be surprised to see a 60mph TS , and by the way is recon headed out to at 7pm est
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Quoting TropicalAnalystwx13:



100 kts.....


SHIPS is based on the GFS model run, and the 12Z GFS is the first GFS run to take Irene only over extreme north Hispaniola, which I assume is the reason for the sudden intenification by SHIPS.
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Harvey is over water again:
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Due to the early and fast start to the season I had originally predicted 17.Now I've bumped it up to 19 name storms.I'll explain when I make a blog later this week.
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Quoting Neapolitan:
Responding to trolls is like intentionally leaving food out for cockroaches to nibble on, then complaining that bugs won't leave you alone.


+1000
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Quoting FLdewey:

Okay I'll bite - which part in your infinite experience isn't true?


Radar doesn't support what he said...It definitely shows the circulation just to the east of St. Croix, and moving WNW.

Ask the others, you'll get the same answer.
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Quoting lucreto:


Not to lessen your experience but Fran was in reality only a Cat.1 imagine a stronger storm


Fran was a Cat 3 when it came onshore. By the time it crossed Central NC, it was not even a Cat 1.
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2445. Grothar
Gee Sorry folks. I posted about the GFDL earlier and forgot to post the graphic. I just woke up from a nap so you will have to excuse me. so here it is. I wonder what the new one will show.

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2443. scott39
The way some of your are living for every model run to go your direction is embarassing! It turns WU into a joke for lurkers who are needing help.
Member Since: June 13, 2009 Posts: 0 Comments: 6912
Quoting USAFwxguy:
Guys the thing you see like directly east of St Croix isn't the "eye"... the CoC is located ese of St Croix along 17.5N, and headed west (map west) set to pass to the south of St Croix


I don't know where you're seeing that because radar doesn't support your claim.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
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2440. Torgen
Quoting weatherman566:


I disagree with that statement. Emily was different. Emily was a much smaller storm, and models such as GFS and ECMWF had a difficult time picking her out. Irene is a large system that the models have seen for days. The models will be more precise with Irene.


Emily also had multiple areas of circulation for most if its life. A true mutant.
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Quoting USAFwxguy:
Guys the thing you see like directly east of St Croix isn't the "eye"... the CoC is located ese of St Croix along 17.5N, and headed west (map west) set to pass to the south of St Croix


Thank you, I just posted that.
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We'll see the eye appear soon I believe...Now that it has likely closed off/is closing off, its eyewall.

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Quoting Gorty:


I blogged about it. check it out.
Nice blog.
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2435. Torgen
Quoting Seflhurricane:
yes we do hopefully we can get a detailed analysis after the 5pm advisory


Well, 5pm EDT is around lunch time for Levi, isnt' it?
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Quoting Gorty:


How serious is this getting? Especially if she doesn't weaken much from crossing the islands?


People are over dramatic IMO. Getting scared before there is a reason. I am currently in the cone and I'll be scared when there is a reason to, not because of what MAY happen. Come on people.....
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am looking forword too the next recon they sould find a eye wall on there rader has well
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting zparkie:
The models will jump all around, because the storm doesnt go in a straight line, spin a top on the ground and see what is does, it spins alittle to the right the models go to the right, it spins alittle to the left, the models go to the left, every four hours they take the average and determine track
Reminds me of that song from the eighties. Irene to the left, Irene to the right,C'mon Irene....
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Responding to trolls is like intentionally leaving food out for cockroaches to nibble on, then complaining that bugs won't leave you alone.
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Quoting NCHurricane2009:


Whoa...what weatherman said that?

This is getting very serious....no joke anymore....


They brought it up when the jetstream pattern changed last week. That it would open up the SE coast for a tropical hit like Fran.
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Quoting Dakster:
xcool is that the eye wall closing off in the radar image?


That's what I said...I think so.
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2426. emcf30
Quoting BahaHurican:
F5... F5... F5... F5...

Oh heck, is it getting that time again?
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Quoting MississippiWx:
The center of Irene is just consolidating and that can give the illusion of a different motion. It's still basically on a WNW heading. If you watch the center, it still goes on the same heading the whole radar loop.





we're in for quite a ride tonight
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Quoting snow2fire:


I live in Cary. They have had hurricane issues in Wake CO. Most problems were due lots of big trees falling in high winds: roads were closed, many houses damaged, and loss of power for up to 2 weeks in the past. So, even though we're not right by the ocean, we can be affected by a hurricane.


Dude...me and you must have been riding out Fran real close...when I said Raleigh...I mean southern Cary...toward the Apex side....
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Quoting USAFwxguy:
Guys the thing you see like directly east of St Croix isn't the "eye"... the CoC is located ese of St Croix along 17.5N, and headed west (map west) set to pass to the south of St Croix


Definitely not true.
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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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