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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I just looked at the NOAA tropical floater loop - last visible pic is 1815Z.

It looks to me like eye is starting to form – and if
that’s the eye, it appears that’s it already at lat
of next forecast point

So is it north of forecast track?
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Quoting A4Guy:


Unless they feel that the easternmost models (HWRF and GFS) are over-doing the strength of the storm. It seems that the models often have trouble with land interaction.
I do think the NHC track will shift East...but stay maybe to the left of the guidance envelope.


TVCN has had two consecutive east shifts today, NHC will move their track to that point, just off the FL East coast.
Member Since: August 19, 2005 Posts: 5 Comments: 5449
1721. ncstorm
Quoting CarolinaHurricanes87:


This is a dramatic shift in the models the past few days. I realize the past week we've had models point from galveston to cape hatteras...... but the last 3 days has been a big change, and consistently east. It looked like the gulf, specifically the panhandle of FL and tampa, were in the bullseye. Now, its looking like the SE US is. This is important because the storm is less than a week away now, and people here in NC are not only unprepared but for the most part dont even know Irene exists. You guys can poke fun at whoever may be exaggerating right now but the fact is, the gulf and florida were expecting this storm, now a whole new group of people is expecting it... with less days to prepare. I am shocked my area of NC is back in play as it looked VERY unrealistic just 2 days ago when the NWS Wilmington specifically said the pattern just didnt seem possible for our area to be affected.

I understand people may be freaking out or whatever, but if the models hold true and this is a SE US storm, people will need to start acting quickly and seriously in the next 3 days


that will come back to bite them if Irene heads our way
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Quoting ProgressivePulse:
18Z TVCN shifted east, passing between Grand Bahama & the FL east coast. Expect the NHC to follow @ 5pm



Interesting...but the UKMET and GFDL still have a western bias. The nhc is still going to split the difference...as long as these models keep showing this...
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1719. BA
nice loop
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1718. nigel20

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and what if it does weaken significantly while traversing Hispaniola? A weak storm would not be affected as much by condition north, as a strong storm would be affected. Right. That's why I think, after it moves over the big island things may change.
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Irene is showing off a less elongated core in the 18z Surface Wind Analysis.

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Interesting.. the UKMET still has the path going into the GOM
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Quoting Gorty:


Anyone? lol


Personally I wouldn't be worried unless you're in an area that would flood.
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Quoting dearmas:


Thank you, was justing getting ready to ask the same....I'm lost ;)

Tampa Fl here


This is a dramatic shift in the models the past few days. I realize the past week we've had models point from galveston to cape hatteras...... but the last 3 days has been a big change, and consistently east. It looked like the gulf, specifically the panhandle of FL and tampa, were in the bullseye. Now, its looking like the SE US is. This is important because the storm is less than a week away now, and people here in NC are not only unprepared but for the most part dont even know Irene exists. You guys can poke fun at whoever may be exaggerating right now but the fact is, the gulf and florida were expecting this storm, now a whole new group of people is expecting it... with less days to prepare. I am shocked my area of NC is back in play as it looked VERY unrealistic just 2 days ago when the NWS Wilmington specifically said the pattern just didnt seem possible for our area to be affected.

I understand people may be freaking out or whatever, but if the models hold true and this is a SE US storm, people will need to start acting quickly and seriously in the next 3 days
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1712. Patrap





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Next couple frames coming on vis imagery will reveal whether that's an eye-like feature or not - right now I'm guessing might well just be a circular patch of dry air rotating around the center lying just SE of it...

And, LOL, it's absolutely impossible to read all comments and even come close to staying current on this blog!
;)
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if the models shift it will not last long...look at those steering maps please..they tell the story. here in Florida you can see the ridge has strengthened today. The 5PM cone will be history later.
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1708. MZT
Quoting WeatherNerdPR:
*Trying* to form an eyewall, I think
It's been a slow wrap all day but it does look better on the south than it did this morning.
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1707. sigh

Quoting hunkerdown:
I believe NC is technically classified a Mid-Atlantic State
Your belief is wrong. I've never heard anyone call NC a Mid-Atlantic state, and officially (i.e., according to the U.S. Census) it's not. The Mid-Atlantic runs from Virginia to New York.
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1706. barbamz
Quoting Progster:


The radar from PR does indeed suggest an eyewall is forming. St Croix may not be a good place for the HH to "hunker down".


Indeed. Webcam St Croix harbour. Not a place to relax, lol
Link
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Quoting charlottefl:


From that radar and from that brief eye poppin' there has been a due west track from St. Kitts...if this continues...Irene will more directly to Hispaniola and models will shift back to the left...
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Quoting P451:


Yeah I'm guessing about 280... seems to be going right for St Croix if you ask me.





lets remmber something for her to miss hispaniola she would have to move at an angle of 291 atm she moving roughyl 280 i dont see it going or PR or north of hispaniola on its current heading it'll go through north central hispaniola after it emerges we'll have a clearer picture of were she wants to go all bets r of until she emerges for hispaniola and what kind of shape she is in
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Quoting RyanFSU:


850-mb Winds, I cannot legally plot up the 10-meter. Multiply by 0.9 :-)
Right. Goofy ECMWF rules...
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Quoting WeatherNerdPR:
*Trying* to form an eyewall, I think.


I can say...THAT is an eye!

:P
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Quoting RyanFSU:
ECMWF 12z tighter zoom: Solid Category 3

Hey I got family down there!.C.S.C needs to watch this one closely.Hugo part two?
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1700. Dennis8
Quoting Abacosurf:
LOL no I am in Naples Fl. But have a home in Abaco.
The airports will be flowing with outbounders trying to leave.


I have a group at Atlantis for a Meeting. Hotel says "Don't worry be HappY" They have underground shelter for my clients IF NEEDED.
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Quoting TerraNova:


I don't think the storm is deep enough to maintain an open eye yet, I'm guessing it'll come and go as the storm continues to strengthen.
Yeah, prolly will come and go.
Quoting robj144:


I don't think that's an eye. If it was, isn't that a rather small eye for such a weak system so far?
True, given the broadness.
Quoting WeatherNerdPR:

I think it'll keep popping it up as it strengthens, not really sustaining it until it reaches 70-75mph. Just a guess, though.
Yup.
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Quoting P451:
A little rapid scan from GOES EAST (until it jumps to the last frame...)


looks like there is still 2 spins in irene
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1697. RyanFSU
Quoting atmoaggie:
Hi Ryan.

Is the MaxWind in those plots for 850 mb or 10 m AGL?


850-mb Winds, I cannot legally plot up the 10-meter. Multiply by 0.9 :-)
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Quoting tiggeriffic:


i think i just threw up a little...GULP


Tigs, you got a little...right....there...

LOL

How's things, toots?
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This was just posted by Oz. Seems a bit ambitious to me.

"TS Irene's center is beginning to relocate to a position further north. There is a very strong likelihood that this cyclone may run right up the Florida peninsula and impact an area somewhere between Jacksonville, FL and the Outer Banks of North Carolina. My plan is to get the broadcast up and running before leaving Tampa and stay on the air throughout Thursday evening, Friday, Saturday & Sunday...without interruption. Stay tuned for more updates as my travel date gets closer."

He has told me yesterday that he wants to drive through Irene as it moves inland. I think he should think twice about doing such a thing especially if it becomes a major.
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Quoting ncstorm:
TWC is showing a new batch of models that that Irene off shore of east coast of FL except one model which still has the West Coast of Florida


Been wondering why that one model has Irene in the gulf. Anyone care to comment?
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Quoting USAFwxguy:
You can see in the CIMMS images below how the Atl high has gained some ground into the FL peninsula, as the CONUS high retreated just a bit

-3hr


Current:


The weakness over the Eastern GoM is facilitated by the retreating CONUS high, as opposed to the Atl high eroding. That should cause Irene to move generally westward in the near term.


This is very significant...showing that Irene is not going to be moving north anytime soon
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1691. A4Guy
Quoting ProgressivePulse:
18Z TVCN shifted east, passing between Grand Bahama & the FL east coast. Expect the NHC to follow @ 5pm



Unless they feel that the easternmost models (HWRF and GFS) are over-doing the strength of the storm. It seems that the models often have trouble with land interaction.
I do think the NHC track will shift East...but stay maybe to the left of the guidance envelope.
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*Trying* to form an eyewall, I think.
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Quoting Surferdude:
WIND SWELL
6am ENE 33mph ESE 15.1 ft @ 11 sec
9am ENE 39mph ESE 18.4 ft @ 12 sec
12pm E 43mph ESE 24.3 ft @ 13 sec
3pm E 44mph ESE 27.2 ft @ 13 sec
6pm ESE 43mph ESE 27.9 ft @ 13 sec


Going to get out the big wave gun and give it a shot out there? I assume you're in PR?

Have a blast but be safe...
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Harvey's remains are getting pulled North from the BOC to join Irene's party!

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Right ..it is funny..when the models shift east all the sleepers from Georgia, Sc and NC come in with their fanatic thoughts on Irene. It's crazy the storm is days away and there are many twists and turns to occur. You people are going to wear yourselves out with this...



Quoting tennisgirl08:
People on here are ridiculous. There is no eye, the storm is moving due west, and there is a lot of uncertainty with regards to track and intensity. No need to overhype this thing right now. Let it play out...
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Quoting shawn26:
It looks to ne moving due west right now
It could fool everyone and keep moving more westerly than no westerly. It's happened plenty of times in the past.
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Decent shift east

Last time before I go.


18z models

Little bit of Hispaniola

FULL IMAGE

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Quoting RyanFSU:
ECMWF 12z tighter zoom: Solid Category 3

Hi Ryan.

Is the MaxWind in those plots for 850 mb or 10 m AGL?
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Quoting CarolinaHurricanes87:



This is correct. Some of the best hockey fans in the country (obviously canada has better), and I myself am a CANIAC!!!

lol, I'm Blues fan myself, but I strongly agrees that Caniacs are one of the best fanbase in sports. Anyway, let's go back on topic :)
Member Since: August 1, 2011 Posts: 28 Comments: 8027
18Z TVCN shifted east, passing between Grand Bahama & the FL east coast. Expect the NHC to follow @ 5pm

Member Since: August 19, 2005 Posts: 5 Comments: 5449
Quoting atmoaggie:
Honestly, *could* be. But will Irene maintain it?



I don't think the storm is deep enough to maintain an open eye yet, I'm guessing it'll come and go as the storm continues to strengthen.
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Looks to me like Irene is moving west again

IR
Link

Visible
Link
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Quoting CarolinaHurricanes87:
WOW!!! I just got home from work and the models have shifted ALOT in the past 24 hours. My area (Wilmington NC) is now directly in the threat area... and if anything, maybe the north side (meaning we'd get the worst of the storm were it to make landfall slightly south of here in SC).

Any thoughts on why these models have moved, if they will slide back east (to florida), and IF it stays over open water coming my way... how strong can this thing get?



They (the models) moved because Irene's center regenerated more northward overnight....

...but these very few hours mean EVERYTHING as to whether this model shift can come to fruition or not. If Irene is going WNW right now...it will go through PR and graze just N of Hispaniola...leaving it un-obstructued to intensify and hit the SE coast (E FL...GA...Carolinas...etc.)

...if it is going west right now...then its going to pass over the S coast or just south of PR...then go right into Hispaniola...get weaker...and take something of a track more like GFDL into SW FL and maybe east GOM....



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This morning's soundings:







*Some* dry air ahead, but Irene doing the moistening bit decently well.
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Link
rough seas and gloomy conditions @ the us virigin islands live webcam
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As I thought, I don't really believes there is an eye there.
Member Since: August 1, 2011 Posts: 28 Comments: 8027
1673. shawn26
If that is a pinhole eye and it is moving due west, it will go under Puerto Rico
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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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