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 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: 5682
Quoting USAFwxguy:


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


lol, no! Its over St. Croix right now!
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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.



there not grounded they will be takeing off at 7pm
Member Since: May 21, 2006 Posts: 5091 Comments: 115085
Quoting NCSaint:


Actually, the HH fleet were some of the first to upgrade to the 6-blade C-130J variant...even more stable in the environment they fly in. Just for info purposes...not a barb by any means


Nice. Maybe in a year when I have my avionics degree and FCC certification; I can find a way in to the maintenance market for the Hunters...
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Quoting Drakoen:
As I had mentioned earlier, it seems as though PR could get a direct hit from Irene.


I agree, what are your thoughts on where she might end up?
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2768. Dakster
taz is that a pinhole eye forming?
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Quoting TropicalAnalystwx13:
Tropical Storm Warnings in Mexico, Harvey expected to become a tropical storm again.

Wow... looks like a Veracruz landfall... can't believe I called that.... lol

And yes, I know the disturbance in the EPac is not Harvey; it just came off Harvey's parent wave...

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Quoting interstatelover7165:
Where? I don't see it.
it's hard to see, but the clouds in center is getting thinner and circular.
Member Since: August 1, 2011 Posts: 28 Comments: 8009
2764. Levi32
Quoting weatherman12345:
I don't blame him. it probably gets repetitive saying the same thing over and over again


I meant no disrespect. Common sense just doesn't support the idea that a 5-day forecast track which is only a 90 mile shift from a state means that the state is safe.

I apologize if I sounded abrupt.
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2763. 7544
shes tightning up now the plane just might find a hurricane when they go in or she might be one a t this hour imo
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Quoting interstatelover7165:
Where? I don't see it.



on the rader you can
Member Since: May 21, 2006 Posts: 5091 Comments: 115085
Quoting VAbeachhurricanes:
Whens recon take off?
The HH that were flying were from Saint Croix..so they grounded for a bit of they went back there before storm hit.
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2758. HarryMc
Quoting NCSaint:


Actually, the HH fleet were some of the first to upgrade to the 6-blade C-130J variant...even more stable in the environment they fly in. Just for info purposes...not a barb by any means


Hey not barb here either. The C130J is the cat's meow. Ever been in the cockpit? All virtual instruments and such... wicked neat.
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Quoting VAbeachhurricanes:
Whens recon take off?



7pm
Member Since: May 21, 2006 Posts: 5091 Comments: 115085
2756. MZT
This is one of the best formed "50 MPH" tropical storms I've ever seen.
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Link

This should clear up the West or WNW question. There is clearly a northern component to Her motion.
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2754. Patrap
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2753. Drakoen
As I had mentioned earlier, it seems as though PR could get a direct hit from Irene.
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Quoting WeatherNerdPR:
Eye showing up:
Where? I don't see it.
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Another view:

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Whens recon take off?
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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.


True about GA...but it would be an anomaly if it hit that state directly. Regardless, Irene will be an interesting one to watch...and looking forward to your future analysis :)
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Quoting NICycloneChaser:


I'm now becoming more certain that that is an eye. Recon will almost certainly find her stronger than 50mph.


An eyewall is definitely forming. This is 0.5 degree tilt out of San Juan. 9,500 ft above the radar site.


It's still open to the NE
Photobucket
Member Since: December 18, 2006 Posts: 7 Comments: 2686
Quoting islander101010:
any suggestions? webcasts with local reports and lots of music
SALsa.LOL
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2746. wpb
gfs 18z run should start soon.

noaa jet flying monday? its data will give the models much more reliability.
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2745. HarryMc
Quoting KEEPEROFTHEGATE:
more like a speed bump no pun or disrespect intended for the people of that island nation hold not long she be gone


I had a contract there from the late 70's to the mid 80's and just haven't been back since. Nice people there back then, probably still. Christianstead had the King Christian and Outrigger... both probably gone by now. But, it's hardly a speedbump.
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2744. NCSaint
Quoting HarryMc:


I think they got it right already. The 4 prop C130 is probably the most stable air-frame out there for heavy weather.


Actually, the HH fleet were some of the first to upgrade to the 6-blade C-130J variant...even more stable in the environment they fly in. Just for info purposes...not a barb by any means
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Quoting islander101010:
any suggestions? webcasts with local reports and lots of music spanish is fine
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Member Since: July 15, 2006 Posts: 17 Comments: 10247
Guys, of all bloggers... I got to say Levi32 and MississippiWx know their stuff the best. I would listen to them very carefully, because trust me they are no wish-caster or doom-caster.
Member Since: August 1, 2011 Posts: 28 Comments: 8009
Quoting mcluvincane:
Guys this is panning out like levi stated in his tidbit. unbelievable how levi is so good at his forecast.


I know!
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2738. Lizpr
Quoting KEEPEROFTHEGATE:
more like a speed bump no pun or disrespect intended for the people of that island nation hold not long she be gone


That's so wrong but funny lol
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South Carolina so far seems to be where it will make a second landfall. Let's hoe new model runs give us some hope for it to stay away from the US.
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Eye showing up:
Member Since: July 7, 2010 Posts: 0 Comments: 5682
Charlotte Amalie St. Thomas, Cyril E. King Airport, Virgin Islands


4 PM (20) Aug 21 80.1 (26.7) 75.9 (24.4) 29.74 (1007) ENE 38 light rain
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2734. Dakster
Quoting HarryMc:


I think they got it right already. The 4 prop C130 is probably the most stable air-frame out there for heavy weather.


I would say whatever they are doing they got it right. After all the years of flying into Hurricanes...
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Quoting luigi18:


SALSA!
any suggestions? webcasts with local reports and lots of music
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Hi Everyone! I usually just lurk but I have a question. I know its still a ways away and I know lots of things can change BUT... Given the current forecast for Irene, what, if anything might Tampa get from this storm? Im not good at deciphering most of the language used on here or reading the maps and such so Laymen's terms would be great!! lol Thanks!
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Thanks USAF; figured but saw the comment about "spinning blades" and just wanted to make sure people didn't think they were flying jet engines in to these things. ;)

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Quoting KanKunKid:


Just think of all that prayer and thoughtfulness wasted on those smug Haitians! If we would have only known, we could have pointed it elsewhere. Probably the Bahamians sitting there without a care in the world, believing Lucreto and suddenly get washed out to sea! Not one prayer for the Bahamians! All wasted on the Haitians camping out and playing scrabble, cooking hotdogs and making smores on a bald mountain.
Mores the pity.
You are SOOOOO wrong... lol
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Quoting Seflhurricane:
they are likely going to issue Hurricane/ Tropical storm Watches for the central bahamas at 5pm
More likey 11 p.m. tonight or 5 a.m. tomorrow. They will want to see how far north Irene gets.

Quoting WeatherNerdPR:

Do storms wobble when closing off their eyewalls? Irene seems to be wobbling WSW.
Storms wobble all the time [like Weebles of old... lol] There's even a name for it... trochoidal? This is one reason why you can't depend on the track as a straight line. The storm wobbles to the left and right of the track. It's also why we don't assume a short-term WNW track is the new direction of the storm. A storm on a westward track will wobble to the WNW, then to the WSW, so that the overall direction of movement over a 6 hour period is due west.


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Quoting barotropic:


I believe that NHC track is such that they want to see just a bit more consistency. Plenty of reason from a model perspective to shift it further east. But since the Bahamas are there and watches etc. are up, you dont want to shift the track over them and than shift it back west again if you can avoid it. I think they will look at the 18Z runs etc. and a track further east will apply then.


That suits me...
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2726. luigi18
Quoting CaicosRetiredSailor:
From St. Croix
via Stormcarib

- Winds are picking up

By Jill Fisher
Date: Sun, 21 Aug 2011 16:24:45 -0400

We've had rain and gusty winds since around noon. The winds are definitely
increasing now. Internet is out, cable is still working, power is still on ...
Hope I didn't jinx it! We've got the backup plan in place - generator and DVD
player ready to go. All is well here :)

~Jill~

Sent from my iPhone


we aware! we here in PR ready to rumble!
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Quoting P451:


You're checking out Harvey?

What do you feel about Irene posing a pretty big threat to you?

I am trying to bear up under the pressure... just realized that in my grocery store run yesterday I forgot to get an extra set of batteries. I have a battery-operated fan coming in, but didn't think to order batteries at the same time... [duh....] So I need to get extra.

Plus I need a USB wireless modem for my Acer so I can blog with that. My Toshiba has no battery life left... Oh. I just remembered the battery backup; I need to set that up....

IOW, I've done most of the essentials.... just got to be in a position to blog as long as phone lines are up... lol
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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.
That depends who the pilot is. The Repubs would say if it's a Democrat he'll fly around in circles wasting money. The Dems would say if it's a Republican he'll stand in place on the ground. And the Tea Party would say the whole idea of HH is unconstitutional.
.
.
There's that wind again...blowing EAST!
Member Since: August 3, 2005 Posts: 10 Comments: 5582
i think the recon will find Irene a hurricane or vary close too one
Member Since: May 21, 2006 Posts: 5091 Comments: 115085

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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.