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 JLPR2:
Interesting look, but lacking a little convection.


WHOA....that is a tad eye-ish...but what if its a coincidence with the random crumpled clouds at the broad center?
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Quoting InTheFloridaKeys:
I believe the NHC has this track nailed.... no doubt in my mind that this is a Florida event


IDK...just the fact that Dr. M mentioned GA, SC and NC has my stomach doing flip flops...thinking i will hit the store tomorrow for a few extra canned things just in case...and gonna work on the ice from the ice maker and empty it every chance i get into bags just in case...not liking this...seriously gonna be critter watching the next few days
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Let's all hope that the NHC forecast for this storm comes to pass.No one needs to be dealing with a major hurricane anywhere in this economy.
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New Dvorak Estimates
UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 21 AUG 2011 Time : 171500 UTC
Lat : 17:08:00 N Lon : 63:47:36 W


CI# /Pressure/ Vmax
3.1 / 999.0mb/ 47.0kt


Final T# Adj T# Raw T#
2.9 2.8 2.8

Center Temp : -38.9C Cloud Region Temp : -47.0C

Scene Type : CURVED BAND with 0.46 ARC in LT GRAY
Maximum CURVED BAND with 0.64 ARC in LT GRAY
at Lat: 18:07:47 N Lon: 62:59:24 W

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : ON
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 105km
- Environmental MSLP : 1012mb

Satellite Viewing Angle : 23.8 degrees

************************************************* ***
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Getting more confident that this may go just east of Florida...but not quite there yet. ECMWF/GFS now leaning that way. So Savannah maybe in the path...still a ways out though.

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Quoting StormJunkie:


The Canadian thinks so...Have seen many a track like this continue to shift E with time. Question is really when does the shifting stop.
not surprised... does this happens everytime a major threatened East Coast like this?
Member Since: August 1, 2011 Posts: 28 Comments: 7902
Katrina wiped Waveland out completely, leveled it......but whatever water came in, moved right out. In NOLA we had a week of flood life, living in canoes, paddling to the store....fun stuff like that.
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Quoting MississippiWx:


The pressure drop is more related to the HH investigating the wrong area.


That makes sense...that might be why winds haven't ramped up significantly despite a low pressure at 999 mb...

And 999 mb and 50 mph winds exercise this is still a broad circulation.....
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St. Maarten is becoming quiet and it's starting to clear up.



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is euro coming out right now?
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1413. 7544
it be funny if the eruo goes with the gfdl and not the gfs whos posting it lets go start the show
Member Since: May 6, 2007 Posts: 0 Comments: 6690
1411. hydrus
Quoting nigel20:

Rapid fire blog, over 1350 comments.
looks like sa bee with arms.
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Ok so im a bit confussed the current center of Irene rests which lat and long?
Member Since: May 23, 2011 Posts: 0 Comments: 91
1409. ncstorm
Well what do you know..NWS in Wilmington, NC has changed it tune..

000
FXUS62 KILM 211738
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
138 PM EDT SUN AUG 21 2011

.SYNOPSIS...
A PIEDMONT SURFACE TROUGH AND A FEW APPROACHING DISTURBANCES ALOFT
WILL PROVIDE A FOCUS FOR SCATTERED THUNDERSTORMS TODAY. MEANWHILE
A COLD FRONT WILL TRACK ACROSS THE AREA LATE MONDAY INTO TUESDAY
SUSTAINING A CHANCE OF RAINFALL. HIGH PRESSURE WILL FOLLOW AND BUILD
INTO THE CAROLINAS WEDNESDAY THROUGH THURSDAY. TROPICAL CYCLONE
IRENE COULD POTENTIALLY IMPACT THE SOUTHEAST STATES AS WE HEAD INTO
NEXT WEEKEND.
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1408. JLPR2
Interesting look, but lacking a little convection.
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Quoting P451:



Don't you understand? Only the following places exist on the map.



Nobody else exists or matters...at all.

When a storm stops threatening any of those regions those individuals disappear entirely. You can already see the NOLA contingent has become sparse on today's blog.



the puerto rican party is still in full effect
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1405. bwi
Passing to the north of buoy 42060

Continuous Winds TIME
(AST) WDIR WSPD
12:50 pm WNW ( 301 deg ) 3.3 m/s
12:40 pm NW ( 315 deg ) 2.0 m/s
12:30 pm WNW ( 295 deg ) 3.0 m/s
12:20 pm SW ( 215 deg ) 5.1 m/s
12:10 pm SW ( 223 deg ) 4.7 m/s
12:00 pm WSW ( 245 deg ) 3.6 m/s
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Quoting zparkie:
South Florida will be in a mess, thousands of forelosed houses with no shutters, the banks wont send anyone out to board them up, windows will go and roofs will fly off, banks will lose millions and tax payers will have to give the banks another 800 billion to stay in business. All those poor people who had to sell thier shutters for scrap metal to survive. I mean anything could happen, it could get into the warm waters of the bahamas and crank up like andrew did, could you imagine? South Florida has the worst unemployment and economy in the country, might create a bunch of work. Hope no one dies and god bless.

You're right. The banks can even keep up with the lawns, pools and other areas of foreclosed homes now, much less what shape they would be in after a bad ts. Great Point.
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1403. WxLogic
Quoting MiamiHurricanes09:
12z Euro initialization:




Let's see if it remain consistent with last run or ???
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Quoting TropicalAnalystwx13:


Nothing to suggest that Irene is strengthening except a drop in pressure from 1006 mb. to 999 mb.


The pressure drop is more related to the HH investigating the wrong area.
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I believe the NHC has this track nailed.... no doubt in my mind that this is a Florida event
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Quoting scott39:
Levi, Is that a new cone on the NHC site? When is the 2pm discussion posted?


Cones and discussions are released at 5 A.M./P.M. and 11 A.M./P.M., not during the 2 A.M./P.M. and 8 A.M./P.M. intermediate advisories.
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Quoting nrtiwlnvragn:


That graphic shows the wind at 900 mb, not at the surface. 12Z HWRF surface winds at the end of the run:

HOUR: 96.0 LONG: -76.70 LAT: 26.00 MIN PRESS (hPa): 940.00 MAX SURF WIND (KNOTS): 101.00
HOUR: 102.0 LONG: -77.30 LAT: 27.40 MIN PRESS (hPa): 936.00 MAX SURF WIND (KNOTS): 104.00
HOUR: 108.0 LONG: -77.90 LAT: 28.50 MIN PRESS (hPa): 935.00 MAX SURF WIND (KNOTS): 102.00
HOUR: 114.0 LONG: -78.70 LAT: 29.70 MIN PRESS (hPa): 934.00 MAX SURF WIND (KNOTS): 103.00
HOUR: 120.0 LONG: -79.20 LAT: 30.80 MIN PRESS (hPa): 933.00 MAX SURF WIND (KNOTS): 108.00
HOUR: 126.0 LONG: -79.90 LAT: 31.80 MIN PRESS (hPa): 933.00 MAX SURF WIND (KNOTS): 107.00


Still a strong storm.


At a 933mb surface pressure, 900 mb would pretty much be right off the deck, a few hundred feet up. So probably not much disparity in the winds at surface vs. winds at 900 mb. Is it going to have a 35kt difference over just a few hundred feet? IDK. At 107kt surface winds, that looks more realisitic.
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Quoting BiloxiGirl:
Can anyone tell me why the UKM Model on Irene has it tracking so much further west? It is so far off it almost looks like the extrapolated run. What would cause this difference?


Don't know but the UK is usually very good.......
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1395. WxLogic
Well GFDL is seeing another possibility if it remains weak... which track wise I agree given that Irene will face land interaction.

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1394. Levi32
Quoting Tropicsweatherpr:
Levi,you think it may become a hurricane before it hits PR?


Doubtful the way the core looks right now, but the NE quad still has some hefty winds with it.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
1393. 7544
gfdl doesnt follow the others this run for sw fla
Member Since: May 6, 2007 Posts: 0 Comments: 6690
1392. Patrap
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Quoting Bluestorm5:
Well, enough with doomcasting... is there ANY chance it'll recuvre out to sea or brush Cape Hatteras?


The Canadian thinks so...Have seen many a track like this continue to shift E with time. Question is really when does the shifting stop.
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Quoting Stormchaser2007:


107 knots is a major hurricane.
*facepalm* I must be tired from last night... I was thinking MPH. 107 knots = high end Category 3. I'm here to learn, not trolling, and I still got long way... sigh.
Member Since: August 1, 2011 Posts: 28 Comments: 7902
Quoting Clearwater1:


Has the gfdl ever been a real player in this storm. I mean, it has constantly been the outlying model. Right?


I really don't put too much faith into the GFDL/HWRF solutions. However, the 12z HWRF solution is not too unbelievable.
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I think the models could eventually trend to NC, instead of SC, we've seen this several times with storms moving up the coast, like Floyd, Fran, Bertha, etc.
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Quoting NCHurricane2009:


Ya' know...before Andrew in 1992 and the 2005 'canes...Hugo was the costliest hurricane in US history....


Yes and it was in 1989. That is 22 years without a CAT 4 hitting the Carolinas. A lot has changed since then and so they have a right to be worried about this one.
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Quoting MississippiWx:


The problem is that it's going to go basically right over PR with the center reformation. There is nothing that hints Irene is strengthening much at this time. Unless convection gets going in earnest, hurricane intensity is probably not going to happen before PR.


Nothing to suggest that Irene is strengthening except a drop in pressure from 1006 mb. to 999 mb.
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Quoting zparkie:
South Florida will be in a mess, thousands of forelosed houses with no shutters, the banks wont send anyone out to board them up, windows will go and roofs will fly off, banks will lose millions and tax payers will have to give the banks another 800 billion to stay in business. All those poor people who had to sell thier shutters for scrap metal to survive. I mean anything could happen, it could get into the warm waters of the bahamas and crank up like andrew did, could you imagine? South Florida has the worst unemployment and economy in the country, might create a bunch of work. Hope no one dies and god bless.
Wow you painted the saddest picture of us south floridians!!!
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Can anyone tell me why the UKM Model on Irene has it tracking so much further west? It is so far off it almost looks like the extrapolated run. What would cause this difference?
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Quoting NCHurricane2009:


IMO...its a close call because pressure dropped to 999 mb...but I don't see a brilliant convective burst over the center either...so I am getting mixed messages about strengthening....

...if this hasn't strengthened wind-wise by 5 PM at all...then I don't see this ever becoming a hurricane before PR....


If I had too GUESS I would guess this is not going to be a major hurricane till late in the track, if it is ever a major hurricane. Its still in a relatively bad place to get its act together, although its obviously trying to ramp up.....its got the land and a little dry air against it.

Too bad Storm W isn't on here cause he was great at looking at the upper level steering, and also finding the ULL that can sheer these things...
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1382. scott39
Levi, Is that a new cone on the NHC site? When is the 2pm discussion posted?
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Quoting TropicalAnalystwx13:


Well, it does have some things to work on, such as the dry air that it is dealing with. However, it is trying to filter it out, and the storm IS strengthening at this time. It should pass by Puerto Rico sometime after midnight tomorrow morning, and may wait until early morning tomorrow morning. If it isn't a hurricane by Puerto Rico, it will be close (65-70 mph or so)


The problem is that it's going to go basically right over PR with the center reformation. There is nothing that hints Irene is strengthening much at this time. Unless convection gets going in earnest, hurricane intensity is probably not going to happen before PR.
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Link

can see the center here on PR radar
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Quoting wolftribe2009:


I LOVE when people start talking about New Orleans Levees and Katrina. All they remember is New Orleans. It ticks me off because Mississippi got the worst of the storm's wrath. I have a friend who lived there during Katrina and he lost his house in the storm as it wiped it right off the beach.

The person above was stating that a CAT 3-4 in SC would be like Katrina in Mississippi. I understood what they meant. Enough on the freaking levee stories.
I know how that feels.Most of the media during Katrina was in NOLA because it was populated and was a major city.But it was actually as you said Mississippi that got the most destruction.The media pulled that trick again during Gustav.They went to NOLA when Baton Rouge got the worst of it.
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Quoting NCHurricane2009:


IMO...its a close call because pressure dropped to 999 mb...but I don't see a brilliant convective burst over the center either...so I am getting mixed messages about strengthening....

...if this hasn't strengthened wind-wise by 5 PM at all...then I don't see this ever becoming a hurricane before PR....


maybe a stronger TS
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1377. nigel20

Rapid fire blog, over 1350 comments.
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Quoting NCHurricane2009:


Ya' know...before Andrew in 1992 and the 2005 'canes...Hugo was the costliest hurricane in US history....


only thing that saved chas from hugo was we got the eye...if it had hit Edisto instead...we would have been toast...but we did get the eye so Awendaw got the worst and that is lower population and fishing community...the were blasted with 20 ft storm surge...aweful...waiting for this one...please to no hugo again...one was enuf for me
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Quoting TropicalAnalystwx13:
uh_oh



straight up winyah bay around Georgetown, SC worse case scenerio for Grand Strand!
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1374. Patrap
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Well, enough with doomcasting... is there ANY chance it'll recuvre out to sea or brush Cape Hatteras?
Member Since: August 1, 2011 Posts: 28 Comments: 7902

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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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