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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We got a new play developing......an ULL is developing in the Caribbean.....this will keep Irene North of the big Islands.
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at least one of the girls is interested in this tropical system... sigh -_-*
Member Since: August 1, 2011 Posts: 28 Comments: 8007
Quoting stormpetrol:


It's called a big ego, I thought he could laugh if the Recon proved him wrong, apparently he can't, its best not to ask!Kinda sad , I always can laugh at myself, hell I ain't no Hurricane expert!


apparently he is using the same form of measurement that my ex husband use to use for....oh wait...i cant post that here...sorry
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Quoting atmoaggie:
Lightning in a convective cell away from center has little meaning...

Lightning in the core *can* mean intensification. Given the cold cloud tops, I wouldn't be surprised.



But, the lightning bit is somewhat confusing. Lightning in the eyewall of a developed hurricane can also signal weakening.


In a developing system with a tightening core it usually signals intensification because of stronger updrafts in the eyewall convection needed to create the supercooled crystals. You are right about already mature major hurricanes...the presence of lightning in those storms rarely means anything.
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Quoting atmoaggie:
If these western outlier GFDL tracks verify, I'll take a picture in a dress.




LOL
Member Since: May 21, 2006 Posts: 5091 Comments: 115081
Quoting pcola57:
Myrtle Grove


Coral Creek.
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5217. JLPR2
Quoting Bluestorm5:
um... what does lightning means in TS? Is it bad?


Usually it is related to rapidly strengthening systems.
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Quoting TampaSpin:
If these western outlier GFDL tracks verify, I'll take a picture in a dress.
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Quoting KEEPEROFTHEGATE:
possible RI flag for storm iam expecting that to commence either just before or after midnight
sigh... just wow. Everything is going "Perfect Storm" for TS Irene...
Member Since: August 1, 2011 Posts: 28 Comments: 8007
Quoting atmosweather:


They found a couple of hurricane force surface winds using the SMFR instrument that were not flagged as suspect, which should be enough for the NHC to upgrade her to hurricane status at 11PM


Yep...that sat appearance is classic of a brand new cat. 1 hurricane...one with a bursting CDO that took it from TS to cat. 1....
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Hey y'all in PR...I usually just lurk, but be safe. Sitting and watching on the AL/FL gulfcoast line. Looks like we are going to be okay...for now at least. Prayers to you in PR.
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5212. nigel20
Quoting alvarig1263:


They're finding 76 MPH surface winds, and 993 MB pressure.

WOW!
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Quoting atmoaggie:
Lightning in a convective cell away from center has little meaning...

Lightning in the core *can* mean intensification. Given the cold cloud tops, I wouldn't be surprised.



But, the lightning bit is somewhat confusing. Lightning in the eyewall of a developed hurricane can also signal weakening.


The flash could have also been a transformer.
Member Since: July 15, 2006 Posts: 17 Comments: 10244
Quoting ecflweatherfan:


First you state that it has begun to turn NW and will recurve, now you state that it will not survive Hispanola. How will it even affect Hispanola if it has already begun the turn and will recurve as you say it has (with no evidence to prove your point to begin with)? Really.

This folks, is the fine example of a troll. Ignore this moron, please. Doesnt know what he/she is talking about. Move on troll, go back to hiding underneath your bridge.


I've already had him on ignore for a while when he said Charley was only a cat 2 at landfall.
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Quoting tiggeriffic:


how is it 100 miles south? if PR is like 40 miles from north to south, and you can see that the eyeish feature is less than half that distance...just askin


It's called a big ego, I thought he could laugh if the Recon proved him wrong, apparently he can't, its best not to ask!Kinda sad , I always can laugh at myself, hell I ain't no Hurricane expert!
Member Since: April 29, 2007 Posts: 0 Comments: 7862
Quoting kmanislander:


They've been up for 3 hours. Not sure how long each mission runs but 6 hours seems a little long.
they still have time. They took off virtually in the center of the storm, so there was no travel time to get there.
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Quoting JLPR2:
While I was on my room, my family saw lightning and you know what lightning in a TS means.
Yeah, ice crystals ...
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Member Since: July 7, 2010 Posts: 0 Comments: 5682
Quoting ackee:
any radio link to what is going on in PR
I know the casinos are open and running.
Just spoke with a friend in one.
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Quoting Grothar:
img src="">


That model clustering I whole-heartedly believe now is rather imminent(GA through Carolinas)....this looks to be the target of Irene with the continued WNW motion and avoidance of Hispaniola...
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Quoting nigel20:
What is recon finding?


They're finding 76 MPH surface winds, and 993 MB pressure.
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Quoting nigel20:
What is recon finding?


They found a couple of hurricane force surface winds using the SMFR instrument that were not flagged as suspect, which should be enough for the NHC to upgrade her to hurricane status at 11PM
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Quoting MiamiHurricanes09:
Blog is in warp speed, lol. Waiting on dat advisory...



yup
Member Since: May 21, 2006 Posts: 5091 Comments: 115081
Quoting zoomiami:


Hi Baha: did my groceries today -- just added a few to the normal weekend stuff. Only thing that I need to check is the battery supply -- can never keep those things in the house.
LOL.... Snap... only thing I forgot to get last night.... I don't usually buy them here. But I am hoping to have a battery operated fan by Wednesday... just in case.... so I need more batteries.... lol
Member Since: October 25, 2005 Posts: 19 Comments: 22087
Quoting interstatelover7165:
Wow, over 5000 posts, 100 pages. How much longer do you think new blog/10000 comments?


We'll have one last push on comments tonight right before, during, and just after the 11pm update. That could get us another 500-1,000 posts and give us total around 6000. However, we have had a few thousand more than that before...We'll make it through the night lol.
Member Since: July 15, 2006 Posts: 17 Comments: 10244
Blog is in warp speed, lol. Waiting on dat advisory...
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Quoting reedzone:
It appears that Hurricane Hunters are now finding our first Hurricane of the Season, Irene. Poses a major threat to Florida Thursday/Friday. 11 p.m. should confirm what the vortex reading shows, 75 mph. Hurricane Irene.


Ehhh be careful saying major threat, I would say it poses a potential threat, in that people should prepare to be safe, but models are continuing to trend east away from Florida, which may contnune to be the trend based on more recent data.

At any rate, Floridians should carefully watch it and do some preparations like making sure they have a hurricane kit/plan, but its not something to lose sleep over yet at all.

The fact that model consensus has shifted away from the West Coast of Florida is why I always stress that people shouldn't hype tropical cyclones in long range. If the models shift back west and stay west, and Irene has 72 hours left of landfall, then we can call Irene a major threat to Florida.

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The only thing REMOTELY reminding me of Katrina from IRENE is thinking we are in the clear, but then worrying we will get a last minute suprise..... hope that was a once in a lifetime experience.
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Gotta love trolls in here...they are ignored so they have to resort to talking to each other...lol...irene might be looking quite scary tomorrow...
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Quoting JLPR2:
While I was on my room, my family saw lightning and you know what lightning in a TS means.
Lightning in a convective cell away from center has little meaning...

Lightning in the core *can* mean intensification. Given the cold cloud tops, I wouldn't be surprised.



But, the lightning bit is somewhat confusing. Lightning in the eyewall of a developed hurricane can also signal weakening.
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5191. nigel20
Quoting Grothar:
img src="">

Irene may just miss Hispaniola in its entirety.
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Quoting midgulfmom:
Dang! Can't read as fast as the blog. I think it's going over the island of PR full lengthwise. Maybe slight bit to the nnw but not much. Just my two cents. We'll see. But looks like the intensive blow up blob is dragging a bit behind the center from the radar pic. (but NOT A PROFFESSIONAL or student of met.) Sounds crazy but I try to imagine the pics in 3D...


f5,f5,f5 should help that :)
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5189. pcola57
Myrtle Grove
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Quoting TampaSpin:


Harumph.
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Quoting MississippiWx:


They can stay longer than 3, especially since they are so close to base. Although, I'm not sure if they will be able to land in St. Croix right now.


I would imagine they will recover to an island east of the system and head home early in the morning. I dont see an attempted landing in St Croix tonight with the SE quad coming through.
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5186. nigel20
What is recon finding?
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Really strong gusts here. Heavy rain too.
Member Since: July 7, 2010 Posts: 0 Comments: 5682
Wow, over 5000 posts, 100 pages. How much longer do you think new blog/10000 comments?
Member Since: August 18, 2011 Posts: 0 Comments: 994
Dang! Can't read as fast as the blog. I think it's going over the island of PR full lengthwise. Maybe slight bit to the nnw but not much. Just my two cents. We'll see. But looks like the intensive blow up blob is dragging a bit behind the center from the radar pic. (but NOT A PROFFESSIONAL or student of met.) Sounds crazy but I try to imagine the pics in 3D...
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Quoting lucreto:
Looks like the system will not survive Hispanola.


First you state that it has begun to turn NW and will recurve, now you state that it will not survive Hispanola. How will it even affect Hispanola if it has already begun the turn and will recurve as you say it has (with no evidence to prove your point to begin with)? Really.

This folks, is the fine example of a troll. Ignore this moron, please. Doesnt know what he/she is talking about. Move on troll, go back to hiding underneath your bridge.
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Quoting Jebekarue:
re post 5143 radar now it looks like the scream mask


I also give a Dvorak 4.0 number along with that sarcasm flag....
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5179. KEEPEROFTHEGATE (Mod)
Quoting Bluestorm5:
um... what does lightning means in TS? Is it bad?
possible RI flag for storm iam expecting that to commence either just before or after midnight
Member Since: July 15, 2006 Posts: 171 Comments: 53815
Quoting gulfbreeze:
Lets not go there.


As a resident of Tallahassee the GFDL run = disaster. I am glad to see it as the outlier but very early and the tracks/Irene could shift west with time.
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Quoting TampaSpin:



Those are 2 very good models......NHC won't move too much right until they too start to move right more.


Agreed!
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5175. Grothar
img src="">
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Quoting NCHurricane2009:


Juding where the CDO is now and where St. Kitts is (Irene passed over St. Kitts this morning)...this has definetly been WNW...and if it continues...this center will only graze the N coast of DR instead of going deep into Hispaniola...not good news at all for Bahamas or US east coast right now...


I'd agree with that, ignoring short term wobbles I can't see her moving far inland once she reaches Hispanola, pattern suggests a WNW motion for the next 24-36 hours.
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Quoting alvarig1263:


It's doing pretty good so far.... lol


Don't quote him, he's a troll.
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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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