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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New steering layer

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Radar is down. HD Radar still working tho. I guess in a few minutes now if not Already Irene will be the first Hurricane to hit the US.
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looks like the models may have shifted
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5920. Drakoen
Irene will have to squeeze through the CONUS ridge and the Subtropical ridge:

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5917. GetReal
At the 54 hour plot for the latest GFS run the east coast trough is no longer there.... Hopefully this is just a bad run on the model, but then again it should have more data to work with.
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5916. tarps3
hr 72

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Quoting BahaHurican:
Shoulda just called it at 11 p.m.


Exactly!
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5914. JLPR2
Still 20-30miles from PR. -_-
Might manage Cat 1 before making its official landfall.
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5913. xcool
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Quoting Dem86Mets:
The 54 hr position is basically the same as the 60 hr position on the 18z GFS.
not per post 5885 its not, its further South at the 54 hours on this 00z run
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Quoting P451:
Recon fixes have this heading:



Radar has this heading:



I guess it'll all come out in the wash come tomorrow AM.





Its all a lie, were all pawns in the Matrix!!! Or we'll know sooner or later.
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5910. tarps3
0z GFS Hr 60



0z GFS HR 66

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5909. Drakoen
Quoting scCane:
So is this simply the windshield whipper effect or do you expect this to actually stick this time?


Could allow Irene to come a bit closer to Florida than the previous runs. I've been juxtaposing the 500mb pattern of both the NAM and GFS 00z runs and they are not dissimilar.
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I'm gone. I gotta get some sleep tonight...
Member Since: October 25, 2005 Posts: 19 Comments: 20733
How much further W is the GFS showing...does it show west Florida coast or something? hmmm....
Member Since: September 15, 2009 Posts: 391 Comments: 3519
A bit further south.

Where Irene exits PR will determine the legacy of this system.

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We are inside the Black Hole....

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Quoting GetReal:
I'm getting a sick feeling if this holds true.
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The 54 hr position is basically the same as the 60 hr position on the 18z GFS.
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Well, TWC have drawn 2 lines in the "cone". One heads for Miami, others heads for Charleston. Between these two is were it can lands, but we still got tons of time.
Member Since: August 1, 2011 Posts: 23 Comments: 7467
Quoting NCHurricane2009:


You would think something as important as a radar would be on generator power or something...C'MON!
Things like that happens here all the time , a lot of imconpetence in the administration,,unfortunately...
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Quoting MiamiHurricanes09:
000
URNT12 KNHC 220358
VORTEX DATA MESSAGE AL092011
A. 22/03:41:30Z
B. 17 deg 54 min N
065 deg 31 min W
C. 850 mb 1348 m
D. 62 kt
E. 157 deg 9 nm
F. 247 deg 63 kt
G. 156 deg 11 nm
H. 989 mb
I. 17 C / 1523 m
J. 22 C / 1515 m
K. 15 C / NA
L. NA
M. NA
N. 12345 / 8
O. 0.02 / 1 nm
P. AF302 0309A IRENE OB 10
MAX FL WIND 67 KT NE QUAD 01:53:40Z
;



No cigars on the cane quite yet...
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Quoting MiamiHurricanes09:
000
URNT12 KNHC 220358
VORTEX DATA MESSAGE AL092011
A. 22/03:41:30Z
B. 17 deg 54 min N
065 deg 31 min W
C. 850 mb 1348 m
D. 62 kt
E. 157 deg 9 nm
F. 247 deg 63 kt
G. 156 deg 11 nm
H. 989 mb
I. 17 C / 1523 m
J. 22 C / 1515 m
K. 15 C / NA
L. NA
M. NA
N. 12345 / 8
O. 0.02 / 1 nm
P. AF302 0309A IRENE OB 10
MAX FL WIND 67 KT NE QUAD 01:53:40Z
;


Interesting that they took 989.9 as 989. I would have thought 990.

Anyway, back in the morning. Good night.
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5898. GetReal
IMO the NAM and GFS may be indicating that the east coast trough will not be as strong as earlier forecast, or quickly lift out allowing bermuda high to ridge further west.
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Quoting P451:
Recon fixes have this heading:



Radar has this heading:



I guess it'll all come out in the wash come tomorrow AM.





Come on P....tell us what you really think. Short term wobble or long term trend?
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Quoting tarps3:
0z GFS Hr 54

Seems to be slowing at 54
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5895. scCane
Quoting Drakoen:
This GFS run is different from the previous runs. The heights to the north of Irene are higher and the trough is lifting out a bit faster.
So is this simply the windshield wiper effect or do you expect this to actually stick this time?
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5894. 7544
looks like this run gfs shifts back west what u think the ridge does look stronger
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Quoting Drakoen:
This GFS run is different from the previous runs. The heights to the north of Irene are higher and the trough is lifting out a bit faster.


500 mb pattern very similar to the 12z and 00z NAM runs.
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Quoting Drakoen:
This GFS run is different from the previous runs. The heights to the north of Irene are higher and the trough is lifting out a bit faster.
meaning what?
Member Since: August 1, 2011 Posts: 23 Comments: 7467
Quoting NCHurricane2009:


Well from the get go...I suspect this run since it had it just south of PR....not making sense at all...and early positioning in a model run means EVERYTHING...

It's still s of Puerto Ricos coasts latitude. It's can still ride the southern portion if the island as long as it keeps moving the same degree as it is now.
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Quoting Abacosurf:
It is technically still south of PR. Center of the center is at 17.9


Post 5874 IMO clearly shows otherwise...I mean that eye is barreling straight into eastern Puerto Rico...not southern....
Member Since: September 15, 2009 Posts: 391 Comments: 3519
are any models running or not until 2?
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Quoting Abacosurf:
Way farther! Hmmm.


And right after the nhc finally shifted further east...lol. I've been saying be leery of the track forecast until all the good models come into better agreement...
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Quoting Drakoen:
This GFS run is different from the previous runs. The heights to the north of Irene are higher and the trough is lifting out a bit faster.


Not to significant though, should end up with a similar result at the end of the run.
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5885. xcool



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Quoting zoomiami:


Looking at this graphic -- the weather field is huge -- it is almost the size of florida. This is what I was talking about earlier about the size of the storm and the widespread effects.

Hi Kman: is your son back at school? or are you coming over next week?
some models have taken Irene up florida's spine,this would cover the whole state and costal waters if she does that...wow
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Quoting MississippiWx:
This is from a different angle, so it's not picking up all of the precip. However, it gives you a good view of the center. Looks to be on a westerly path and should graze the Southern part of PR.



Excellent view... lets you predict the path...
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5882. tarps3
0z GFS Hr 54

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Quoting Relix:
Emily is a hurricane? Not surprising.
Emily is passing through PR? Not surprising.
That PR still has power? HOLY *^*^%#
lol!
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5880. luigi18
Quoting Relix:
Emily is a hurricane? Not surprising.
Emily is passing through PR? Not surprising.
That PR still has power? HOLY *^*^%#


Lol
Member Since: September 21, 2008 Posts: 0 Comments: 470
000
URNT12 KNHC 220358
VORTEX DATA MESSAGE AL092011
A. 22/03:41:30Z
B. 17 deg 54 min N
065 deg 31 min W
C. 850 mb 1348 m
D. 62 kt
E. 157 deg 9 nm
F. 247 deg 63 kt
G. 156 deg 11 nm
H. 989 mb
I. 17 C / 1523 m
J. 22 C / 1515 m
K. 15 C / NA
L. NA
M. NA
N. 12345 / 8
O. 0.02 / 1 nm
P. AF302 0309A IRENE OB 10
MAX FL WIND 67 KT NE QUAD 01:53:40Z
;
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Still Port or south of Track



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5877. Drakoen
This GFS run is different from the previous runs. The heights to the north of Irene are higher and the trough is lifting out a bit faster.
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I'm no weather expert but when I checked in earlier the center was southeast of St Croix...Next I look it's northwest...How is that not at least WNW movement?
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Quoting NCHurricane2009:


Well from the get go...I suspect this run since it had it just south of PR....not making sense at all...and early positioning in a model run means EVERYTHING...
It is technically still south of PR. Center of the center is at 17.9
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Quoting NCHurricane2009:


Well from the get go...I suspect this run since it had it just south of PR....not making sense at all...and early positioning in a model run means EVERYTHING...
but it was initialized at 8pm I believe, and at that time the center would have been just south or at least on the south side of PR
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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.