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.

Links
Long-range radar out of Puerto Rico

Jeff Masters

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Quoting Levi32:
000
URNT12 KNHC 220021
VORTEX DATA MESSAGE AL092011
A. 22/00:05:00Z
B. 17 deg 51 min N
065 deg 01 min W
C. 850 mb 1383 m
D. 55 kt
E. 314 deg 46 nm
F. 040 deg 58 kt
G. 294 deg 37 nm
H. 994 mb
I. 16 C / 1524 m
J. 20 C / 1520 m
K. 18 C / NA
L. NA
M. NA
N. 12345 / 8
O. 0.02 / 3 nm
P. AF302 0309A IRENE OB 03
MAX FL WIND 58 KT NW QUAD 23:52:40Z
MAX FL TEMP 21 C 273 / 10 NM FROM FL CNTR



looks like the winds will be going up
Member Since: May 21, 2006 Posts: 5091 Comments: 115362
Center fix located WNW of Past, and pressure dropped to 994 Now, PR will be the caribbean island to be hit, Hispanoila and Cuba will be spared, though with those two being spared the US will not
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FWIW, ATCF says:

AL, 09, 2011082200, , BEST, 0, 179N, 650W, 50, 994, TS, 50, NEQ, 30, 0, 0, 30, 1010, 125, 30, 0, 0, L, 0, , 0, 0, IRENE, M,
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4120. Patrap
TS IRENE Building a SOlid core slowly but confidently tonight in Warm SST's and low Shear.

Member Since: July 3, 2005 Posts: 426 Comments: 129093
4119. GoWVU
Quoting presslord:
as to Charleston evac...the islands are likely to be under mandatory evac...possibly as far inland as Hwy 17...virtually no chance of anything west of 17 seeing a mandatory evac


you really think that press? There is lots of low lands if that thing comes our way
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Got a brief gust. Weird how it got quiet as soon as it started LOL
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Quoting NCSCguy:
North Charleston, right next to Trident Tech, but I work in West Ashley.


I work in West Ashley too LOL
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Quoting NCSCguy:
North Charleston, right next to Trident Tech, but I work in West Ashley.


see post 4106
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Quoting Levi32:


I noted a bit ago that she had slowed down on radar, and as I said then, I think the reason is the center trying to organize around the stronger convective bands that are developing to the east and north. That can lead to slowing.


How would a sudden slow down affect the future track in your eyes?
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4112. ncstorm
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Recon supports a 65 mph storm.
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Quoting HurricaneIrene:


No there won't, and that can be accredited to the latest GFDL run.


Noticed that you just joined, welcome to WU.
Member Since: September 2, 2006 Posts: 110 Comments: 6878
Quoting aquak9:

It's ok, man...lotsa folk gettin' fussy.
Aqua,

I think Irene might be smelling your Blueberry Muffins.
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as to Charleston evac...the islands are likely to be under mandatory evac...possibly as far inland as Hwy 17...virtually no chance of anything west of 17 seeing a mandatory evac
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Tropical Depression Harvey looking good...May make Tropical Storm status again soon..

Member Since: July 6, 2010 Posts: 113 Comments: 32532




Dead centre of Track, going to miss PR/Haiti.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
4103. Levi32
000
URNT12 KNHC 220021
VORTEX DATA MESSAGE AL092011
A. 22/00:05:00Z
B. 17 deg 51 min N
065 deg 01 min W
C. 850 mb 1383 m
D. 55 kt
E. 314 deg 46 nm
F. 040 deg 58 kt
G. 294 deg 37 nm
H. 994 mb
I. 16 C / 1524 m
J. 20 C / 1520 m
K. 18 C / NA
L. NA
M. NA
N. 12345 / 8
O. 0.02 / 3 nm
P. AF302 0309A IRENE OB 03
MAX FL WIND 58 KT NW QUAD 23:52:40Z
MAX FL TEMP 21 C 273 / 10 NM FROM FL CNTR
Member Since: November 24, 2005 Posts: 635 Comments: 26685
One thing for sure Irene covers a large area!
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4100. JRRP
Quoting Stormchaser2007:
Did the westcasters stop yet?

lol
Member Since: August 16, 2007 Posts: 0 Comments: 6165
Quoting bigeasystormcaster:
Looks as though Irene has resumed a more westerly track or 270 degrees At 8:15PM eastern time it appears that it is located at 17.5N 65.0W and that the center is just SW of a recent blow-up of thunderstorms. Please confirm this observation if anyone would care to do so.



Lowest pressure on 1st pass: 995.4mb, at 17.78N.

Lowest pressure on 2nd pass: 994.9mb, at 17.85N.

Irene is not moving due west, but WNW.
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4098. Levi32
Quoting CaneAddict:


I'd think that's due to Irene building an eyewall...what do you think is the cause of this?


I noted a bit ago that she had slowed down on radar, and as I said then, I think the reason is the center trying to organize around the stronger convective bands that are developing to the east and north. That can lead to slowing.
Member Since: November 24, 2005 Posts: 635 Comments: 26685
4096. NCSCguy
Quoting presslord:


lottsa variables to that. What part o' town are you in?
North Charleston, right next to Trident Tech, but I work in West Ashley.
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Irene should be able to get ot 65 mph or 70 mph before getting to PR...
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El Conando we havent had birds in SW Fla either!
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Post 4010. I was one of the folks that excpected a TS in the BOC.
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Quoting aquak9:

They had Ike making landfall in Miami as a Cat 3 at one point, I believe....



Doesn't mean they're 800 miles off. A degree of longitude over a long distance adds up. If you take the Eastern edge of their cone at day 5 it takes you right to SC's doorstep. It's pretty much within the cone.
Member Since: December 18, 2006 Posts: 7 Comments: 2687
Irene looks better than some hurricanes.
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Quoting zparkie:
Charleston? that would mean the NHC would be about 800 miles off, I dont think they make that big of mistakes.



what aqua said
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Quoting weatherguy74:

Brett that is the new run

Thanks
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4086. Levi32
Member Since: November 24, 2005 Posts: 635 Comments: 26685
Just what Irene needed.
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Did the westcasters stop yet?
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4082. Patrap
..my eyes burn..
Member Since: July 3, 2005 Posts: 426 Comments: 129093
4081. 7544
i think irene is on her way of being the first atlantice hurricane
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Quoting zparkie:
Charleston? that would mean the NHC would be about 800 miles off, I dont think they make that big of mistakes.


See post 4001.
Member Since: September 2, 2006 Posts: 110 Comments: 6878
Quoting bigeasystormcaster:
Looks as though Irene has resumed a more westerly track or 270 degrees At 8:15PM eastern time it appears that it is located at 17.5N 65.0W and that the center is just SW of a recent blow-up of thunderstorms. Please confirm this observation if anyone would care to do so.


No, your wrong
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Doc needs to change the title of this post to Dangerous Irene headed towards Puerto Rico. I guess we will be getting an update soon.
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Quoting Bretts9112:

is that new or is that old?

Brett that is the new run
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4076. GoWVU
Quoting zparkie:
Charleston? that would mean the NHC would be about 800 miles off, I dont think they make that big of mistakes.


Charleston is right in the middle, soooo I have to think we are not out of danger, and by looking at the models lots pointing this way
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Quoting NCSCguy:
Hi this is my first post but I have been lurking for several years now. I currently live in Charleston and was wondering about how far out does a storm have to be before they start issuing evacuation notices? I can't get off work to head for higher ground until they do.


lottsa variables to that. What part o' town are you in?
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Quoting Levi32:
Recon last went through the center 98 minutes ago, and Irene traveled about 19 miles in that time. That is a forward speed of about 12mph.


I'd think that's due to Irene building an eyewall...what do you think is the cause of this?
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Quoting zparkie:
Thats funny , no birds here in south florida, must be knowing something we dont, my cat is acting funny too, keeps looking outside at the sky.


An ant said said hello to me today while I was on the phone. Whoops! I mean aunt.
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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.