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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Quoting Drakoen:
As I had mentioned earlier, it seems as though PR could get a direct hit from Irene.


Hey Drak, interested to hear your thoughts on track?
Member Since: July 17, 2008 Posts: 0 Comments: 1242
2822. KEEPEROFTHEGATE (Mod)
09L/TS/I/C0
MARK
17.85N/64.70W
Member Since: July 15, 2006 Posts: 163 Comments: 52242
Quoting violet312s:


I'm thinking 7:04 lol
some who are old enough will remeber this -7-14 thats a good time any time
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Quoting luigi18:


salsoul98.5

thanks tomorrow you guys are getting it think i'll listen to the music of st croix tonight it seems heavy rains and winds high in low 80s music keeps flowing cant be all bad
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2819. Patrap
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ACE 2011 Hurricane Season:
Arlene 1.63
Bret 2.95
Cindy 1.84
Don 1.50
Emily 1.99
Franklin 0.405
Gert 1.60
Harvey 1.23(Probably 1.465 by death)
Irene 0.81(So Far)

Total Ace: 13.96(After Harvey: Total ACE~14.19)
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When will recon be getting in there again?
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http://www.wunderground.com/radar/radblast.asp?zoom mode=pan&prevzoom=zoom&num=6&frame=0&delay=15&scal e=1.000&noclutter=0&ID=JUA&type=N0R&showstorms=0&l at=18.46724892&lon=-66.10896301&label=San%20Juan,%2 0PR&map.x=400&map.y
Member Since: August 18, 2011 Posts: 0 Comments: 994
2815. shawn26
I rely heavily on what Levi says.
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2814. xcool
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2813. luigi18
Quoting islander101010:
any suggestions? webcasts with local reports and lots of music

http://www.salsoul.com/
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Tracks will bounce around till probally thursday. If she goes north of hispanola then we could see a cat 2 for sure.......
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Quoting Levi32:
1001mb at St. Croix and falling like a rock.



How often does that update?
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2809. Levi32
Quoting RussianWinter:
Hi guys! I have been a long time lurker but decided to post. I'm transferring to FSU next year to study meteorology and this blog has been relevant to my interests.

Earlier someone made a post claiming Irene was wobbling to the southwest. I'm not so sure about that since it appears to me that there is a southern expansion of convection rather than a southwest wobble.

Irene was my first storm after arriving in the United States so this storm is sort of personal to me.



Welcome to the blog. I believe some are focusing too much on the "eye" feature on radar, which is not really an eye, and draws the human eye to it as the center of the storm, when reality the center is on the southeast side of that clear area. Thus, the clear area will naturally rotate southwest and give the illusion of a wobble in that direction.
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Wow...Look at the outflow on the NW quadrant..*breaks down in tears* Beautiful !

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Quoting TropicalAnalystwx13:


Levi, if the only land it has to contend with is Puerto Rico, exactly how strong could the system get?

Just a guesstimate.


Easily a major hurricane..based on the current conditions.
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Man, this really is a squeaker. If Irene stays on the NHC course and goes over the mts and does not weaken to the point of reorganizing, then there is plenty of time over very warm water, before slamming into S. FL.

On the other hand, if it is weakened substantially, and happens to reorganize just a little to the west, then watch out W FL and central FL .. I think the ukmet handles it in that manner, at least it's last run did.

It's all about timing and minute degrees. Stating the obvious, but a good one to track.
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2805. Drakoen
Not sure if this was already posted, but the ECWMF and the ECMWFEPS are not too far off. With the ECMWFEPS on the left, and the ECWMF operational on the right Florida needs to continue to monitor this system.
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2804. Levi32
1001mb at St. Croix and falling like a rock.

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Quoting StormJunkie:


Radar looks like it has it going right over St. Croix...Am I missing something?

Radar updates frecuently...satellite imagery takes about 30 minutes. He should look at radar.
Member Since: July 7, 2010 Posts: 0 Comments: 5521
Quoting StormJunkie:


Radar looks like it has it going right over St. Croix...Am I missing something?


No, your right, its going right over St. Croix right now.
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Hi guys! I have been a long time lurker but decided to post. I'm transferring to FSU next year to study meteorology and this blog has been relevant to my interests.

Earlier someone made a post claiming Irene was wobbling to the southwest. I'm not so sure about that since it appears to me that there is a southern expansion of convection rather than a southwest wobble.

Irene was my first storm after arriving in the United States so this storm is sort of personal to me.

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Quoting P451:


Yep.

It's going northsouthwest. No! Wait! Now it's going westnortheast! No, wait it's going to NOLA! Ut oh, look out Cabo San Lucas! Holy crap it's heading to Trinidad.

Nope, nope, now it's going back WNW towards PR, false alarm, sorry everyone!


(see avatar....)
Lets not forget "a shift to the left, no right, no left..and another good one, is that an eye??
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Quoting Tazmanian:



it has vary small land too go overe and vary flat land too


+10000
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2798. Patrap
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sitting here in central florida wishing for just a ts storm here out of it and 8 to 10 inches of rain........... I'm a fishhead and the culverts around here should would be flowing and great for me fishing :)
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Quoting barotropic:


I think you may be right. As a matter of fact I dont see a WNW movement. Maybe slightly N of due west.


I agree as well...on visible imagery..it appears that Irene will be south of it's next point or two unless it starts to move in a more northward direction..all I see is a due west movement at this time.
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Quoting Levi32:
We're still waiting for healthier convection to envelope Irene's core, like the kind that was firing last night.



Levi, if the only land it has to contend with is Puerto Rico, exactly how strong could the system get?

Just a guesstimate.
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Quoting P451:


Why even take off? Just sit on the tarmac with the instruments on and let the storm move overhead.



Open airplane door and drop a dropsode from the plane right onto the tarmac
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Quoting MississippiWx:
If you're Puerto Rico, this thing can't come ashore fast enough as it's strengthening nicely now.




it has vary small land too go overe and vary flat land too
Member Since: May 21, 2006 Posts: 5089 Comments: 114050
Quoting neonlazer:
The HH that were flying were from Saint Croix..so they grounded for a bit of they went back there before storm hit.
they can do their test on ground they are in the center of it
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2789. luigi18
Quoting islander101010:
any suggestions? webcasts with local reports and lots of music
Quoting islander101010:


salsoul98.5

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2788. KEEPEROFTHEGATE (Mod)
Quoting Levi32:
We're still waiting for healthier convection to envelope Irene's core, like the kind that was firing last night.

at midnight tonight
Member Since: July 15, 2006 Posts: 163 Comments: 52242
Quoting USAFwxguy:


ese of St Croix, set to pass a bit south. Agree?


Radar looks like it has it going right over St. Croix...Am I missing something?
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2784. Levi32
We're still waiting for healthier convection to envelope Irene's core, like the kind that was firing last night.

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Quoting Levi32:


That's fine. Some will disagree with me on this one. Everyone in Florida should keep an eye on the situation, but in my mind the northward shift last night and this morning sealed the deal to be Florida or farther north.

Also, it's very bad to say Georgia won't get hit simply because they haven't been hit in forever. This is exactly the kind of storm that could do it, like David in 1979.


That's exactly right. Climatology really has nothing to do with whether or not a storm can go to a certain place. I'd say Levi's right on when he's telling people from Florida northward should be paying attention to this storm. They had better be aware of what's going on. This is no joke.
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Quoting P451:


Levi spent all night traveling via dog sled. The guy deserves a break.



Don't know whether to laught out loud or not, since I don't know if you are telling the truth!
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Come on guys give Levi a break. He's one of the main guys here and we all rely on him for info. Lets keep in mind these storms are not perfect science. We all need to use a bit of common sense. These storms can mess with the best of minds. Just saying...
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2779. ackee
any pic from PR or st crox for me think IRENE going jump north past north of hispanola guess we see
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If you're Puerto Rico, this thing can't come ashore fast enough as it's strengthening nicely now.

Member Since: July 15, 2006 Posts: 17 Comments: 10156
2777. Patrap
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http://www.gotostcroix.com/live/harborcam.php

Calm in St. Croix now. Give it about 30 mins or so then the backside will come in.
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Quoting Dakster:
taz is that a pinhole eye forming?



no
Member Since: May 21, 2006 Posts: 5089 Comments: 114050
Quoting USAFwxguy:


Should I go ahead and second that?


You sure can, though many might not agree, what we are calling all a eye feature is more like a closed off dry spot, the actual center is actually at the bottom of that feature and is not the "feature" itself, JMO.
Member Since: April 29, 2007 Posts: 0 Comments: 7506
Quoting interstatelover7165:
Where? I don't see it.

That dent in the clouds east of St. Croix, seems to be trying to show the eye off.
Member Since: July 7, 2010 Posts: 0 Comments: 5521

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About JeffMasters

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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