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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cone shifted right via TWC .... 70MPH
Member Since: Posts: Comments:
Received a message from a friend that my earlier post was deleted for "volating community standards". I apologize. Thought I was providing some info about a weather site that other members had requested.

I read the community standards and don't understand the violation, but so be it.

Steel
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...IRENE STRENGTHENING AS IT APPROACHES PUERTO RICO...

11:00 PM AST Sun Aug 21
Location: 17.9°N 65.5°W
Max sustained: 70 mph
Moving: WNW at 15 mph
Min pressure: 993 mb
Member Since: Posts: Comments:
5369. yoboi
tracking west watch tomm eve nola will be in the cone
Member Since: Posts: Comments:
5368. luigi18
Quoting goldenpixie1:
G'evening all! Waiting on the latest news and possible upgrade. Hope y'all are safe!

Thanks
Bayamon,Pr blowing nicely!
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Quoting interstatelover7165:
000
WTNT44 KNHC 212045
TCDAT4

TROPICAL STORM IRENE DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011
500 PM AST SUN AUG 21 2011

IRENE IS GRADUALLY BECOMING BETTER ORGANIZED IN ITS APPEARANCE ON
SATELLITE IMAGES...WITH CURVED BANDS BECOMING BETTER DEFINED. THE
CURRENT INTENSITY IS HELD AT 45 KT IN ACCORDANCE WITH OBSERVATIONS
EARLIER THIS AFTERNOON FROM THE AIR FORCE HURRICANE HUNTERS.
ANOTHER HURRICANE HUNTER PLANE IS SCHEDULED TO INVESTIGATE IRENE
AROUND 0000 UTC. WITH A WELL-DEFINED UPPER-LEVEL OUTFLOW
ANTICYCLONE SITUATED OVER THE STORM...THE PRIMARY IMPEDIMENT TO
STRENGTHENING OVER THE NEXT COUPLE OF DAYS SHOULD BE LAND
INTERACTION. IF IRENE MOVES OVER MORE OF HISPANIOLA OR OVER PARTS
OF EASTERN CUBA IT WILL LIKELY BE WEAKER THAN INDICATED
HERE...HOWEVER IF THE SYSTEM ENDS UP MOVING TO THE NORTH OF BOTH OF
THOSE LAND MASSES IT COULD STRENGTHEN MORE THAN EXPECTED. THE
OFFICIAL INTENSITY FORECAST IS SOMEWHAT HIGHER THAN THE LATEST LGEM
STATISTICAL-DYNAMICAL GUIDANCE.

THE FORWARD MOTION HAS SLOWED A BIT AND IS NOW NEAR 285/15. IRENE
CONTINUES TO BE STEERED BY THE FLOW ON THE SOUTH SIDE OF A
MID-LEVEL SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC. THE
WEST-NORTHWESTWARD MOTION IS LIKELY TO CONTINUE FOR 1 TO 2 DAYS
WHICH WOULD BRING THE CENTER NEAR OR OVER PUERTO RICO...AND NEAR OR
OVER THE DOMINICAN REPUBLIC. OVER THE NEXT FEW DAYS...A COUPLE OF
TROUGHS ARE FORECAST TO CREATE A WEAKNESS IN THE RIDGE NEAR THE
SOUTHEAST U.S. COAST WHICH SHOULD INDUCE A TURN TO THE RIGHT AROUND
DAY 3. SEVERAL OF THE RELIABLE TRACK GUIDANCE MODELS SUCH AS THE
ECMWF AND GFS HAVE SHIFTED EASTWARD FROM THEIR PREVIOUS RUNS AND SO
HAS THE DYNAMICAL CONSENSUS. THE OFFICIAL TRACK FORECAST HAS BEEN
SHIFTED A LITTLE TO THE RIGHT OF THAT FROM THE PREVIOUS ADVISORY
AND LIES ON THE WESTERN SIDE OF THE GUIDANCE ENVELOPE. IT IS
IMPORTANT NOT TO FOCUS ON THE EXACT FORECAST TRACK...ESPECIALLY AT
DAYS 4 TO 5 SINCE THE MOST RECENT 5-YEAR AVERAGE ERRORS AT THOSE
FORECAST TIMES ARE 200 AND 250 MILES RESPECTIVELY.

FORECAST POSITIONS AND MAX WINDS

INIT 21/2100Z 17.7N 64.4W 45 KT 50 MPH
12H 22/0600Z 18.2N 66.6W 60 KT 70 MPH...INLAND
24H 22/1800Z 18.9N 69.3W 65 KT 75 MPH...INLAND
36H 23/0600Z 19.6N 71.5W 50 KT 60 MPH...INLAND
48H 23/1800Z 20.3N 73.5W 50 KT 60 MPH...OVER WATER
72H 24/1800Z 22.7N 76.7W 60 KT 70 MPH
96H 25/1800Z 25.5N 79.5W 75 KT 85 MPH
120H 26/1800Z 28.5N 81.5W 50 KT 60 MPH...INLAND

$$
FORECASTER PASCH




old
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
LOL, NHC must lurk on here.


Lol...I was wrong. My track had not updated from 11AM this morning for some reason. It's east.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
11:00 PM AST Sun Aug 21
Location: 17.9N 65.5W
Max sustained: 70 mph
Moving: WNW at 15 mph
Min pressure: 993 mb

just as said , go back and look
Quoting stormpetrol:
Wouldn't surprise me to see the NHC keep at it WNW or even 70 mph!just saying....., if they upgrade to hurricane 75mph with movement West would surprise the hell out of me , just been watching them too long.....

Oh wait I found it , goodnight!
Member Since: April 29, 2007 Posts: 0 Comments: 7663
Note the continued rightward shift of the cone....the chances of an east coast major event continue to rise...
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Quoting southbeachdude:
cone shifted right via TWC .... 70MPH
Left...actually.
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5362. ncstorm
Member Since: August 19, 2006 Posts: 13 Comments: 14420
5361. Relix
Consistency I guess
Member Since: August 3, 2006 Posts: 0 Comments: 2646
Why not designate "ONE" person to post the update..
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5359. nigel20
Quoting Tazmanian:




yup

Taz saw your comment earlier and you're right, we are already over 5300 comments.
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cone shifted right via TWC .... 70MPH
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Path shifted to east.
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Cone moved east !
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Quoting MississippiWx:
Farther west with track. LOL.

LOL, NHC must lurk on here.
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5354. emguy
I knew they would be hardpressed to upgrate to hurricane with a 993 MB pressure. They usually look at 988 as the threashold and the storm is still washing out some dry air near the center.
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cone shifted right via TWC .... 70MPH
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Tropical Storm IRENE Storm Archive
...IRENE STRENGTHENING AS IT APPROACHES PUERTO RICO...
11:00 PM AST Sun Aug 21
Location: 17.9°N 65.5°W
Max sustained: 70 mph
Moving: WNW at 15 mph
Min pressure: 993 mb
Member Since: Posts: Comments:
Quoting weatherguy03:
I still believe South Carolina/North Carolina is going to feel the brunt of Irene.
Irene won't be able to make it that far north due to the ridge rebuilding west
Member Since: Posts: Comments:
BULLETIN
TROPICAL STORM IRENE ADVISORY NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011
1100 PM AST SUN AUG 21 2011

...IRENE STRENGTHENING AS IT APPROACHES PUERTO RICO...



SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.9N 65.5W
ABOUT 50 MI...75 KM WNW OF ST. CROIX
ABOUT 50 MI...85 KM SE OF SAN JUAN PUERTO RICO
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...993 MB...29.32 INCHES
Member Since: Posts: Comments:
000
WTNT44 KNHC 212045
TCDAT4

TROPICAL STORM IRENE DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011
500 PM AST SUN AUG 21 2011

IRENE IS GRADUALLY BECOMING BETTER ORGANIZED IN ITS APPEARANCE ON
SATELLITE IMAGES...WITH CURVED BANDS BECOMING BETTER DEFINED. THE
CURRENT INTENSITY IS HELD AT 45 KT IN ACCORDANCE WITH OBSERVATIONS
EARLIER THIS AFTERNOON FROM THE AIR FORCE HURRICANE HUNTERS.
ANOTHER HURRICANE HUNTER PLANE IS SCHEDULED TO INVESTIGATE IRENE
AROUND 0000 UTC. WITH A WELL-DEFINED UPPER-LEVEL OUTFLOW
ANTICYCLONE SITUATED OVER THE STORM...THE PRIMARY IMPEDIMENT TO
STRENGTHENING OVER THE NEXT COUPLE OF DAYS SHOULD BE LAND
INTERACTION. IF IRENE MOVES OVER MORE OF HISPANIOLA OR OVER PARTS
OF EASTERN CUBA IT WILL LIKELY BE WEAKER THAN INDICATED
HERE...HOWEVER IF THE SYSTEM ENDS UP MOVING TO THE NORTH OF BOTH OF
THOSE LAND MASSES IT COULD STRENGTHEN MORE THAN EXPECTED. THE
OFFICIAL INTENSITY FORECAST IS SOMEWHAT HIGHER THAN THE LATEST LGEM
STATISTICAL-DYNAMICAL GUIDANCE.

THE FORWARD MOTION HAS SLOWED A BIT AND IS NOW NEAR 285/15. IRENE
CONTINUES TO BE STEERED BY THE FLOW ON THE SOUTH SIDE OF A
MID-LEVEL SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC. THE
WEST-NORTHWESTWARD MOTION IS LIKELY TO CONTINUE FOR 1 TO 2 DAYS
WHICH WOULD BRING THE CENTER NEAR OR OVER PUERTO RICO...AND NEAR OR
OVER THE DOMINICAN REPUBLIC. OVER THE NEXT FEW DAYS...A COUPLE OF
TROUGHS ARE FORECAST TO CREATE A WEAKNESS IN THE RIDGE NEAR THE
SOUTHEAST U.S. COAST WHICH SHOULD INDUCE A TURN TO THE RIGHT AROUND
DAY 3. SEVERAL OF THE RELIABLE TRACK GUIDANCE MODELS SUCH AS THE
ECMWF AND GFS HAVE SHIFTED EASTWARD FROM THEIR PREVIOUS RUNS AND SO
HAS THE DYNAMICAL CONSENSUS. THE OFFICIAL TRACK FORECAST HAS BEEN
SHIFTED A LITTLE TO THE RIGHT OF THAT FROM THE PREVIOUS ADVISORY
AND LIES ON THE WESTERN SIDE OF THE GUIDANCE ENVELOPE. IT IS
IMPORTANT NOT TO FOCUS ON THE EXACT FORECAST TRACK...ESPECIALLY AT
DAYS 4 TO 5 SINCE THE MOST RECENT 5-YEAR AVERAGE ERRORS AT THOSE
FORECAST TIMES ARE 200 AND 250 MILES RESPECTIVELY.

FORECAST POSITIONS AND MAX WINDS

INIT 21/2100Z 17.7N 64.4W 45 KT 50 MPH
12H 22/0600Z 18.2N 66.6W 60 KT 70 MPH...INLAND
24H 22/1800Z 18.9N 69.3W 65 KT 75 MPH...INLAND
36H 23/0600Z 19.6N 71.5W 50 KT 60 MPH...INLAND
48H 23/1800Z 20.3N 73.5W 50 KT 60 MPH...OVER WATER
72H 24/1800Z 22.7N 76.7W 60 KT 70 MPH
96H 25/1800Z 25.5N 79.5W 75 KT 85 MPH
120H 26/1800Z 28.5N 81.5W 50 KT 60 MPH...INLAND

$$
FORECASTER PASCH
Member Since: August 18, 2011 Posts: 0 Comments: 994
TWC said it's increased to 70mph.
Member Since: Posts: Comments:
New advisory out!!!
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5345. Grothar
Quoting Swede38:


Svensk?


Norsk!
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5344. Skyepony (Mod)
Looks like a brief tornado vortex just went over the radar site, at San Juan, PR. It's still working..
Member Since: Posts: Comments:
70mph
Member Since: Posts: Comments:
5342. Dzstr
000
WTNT84 KNHC 220249
TCVAT4

IRENE WATCH/WARNING BREAKPOINTS/ADVISORY NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011
1100 PM AST SUN AUG 21 2011

.TROPICAL STORM IRENE

PRZ001-002-003-004-005-006-007-008-009-010-011-01 2-013-220900-
/O.CON.KNHC.HU.W.1009.000000T0000Z-000000T0000Z/
1100 PM AST SUN AUG 21 2011

PUERTO-RICO 18.22N 66.44W
VIEQUES 18.12N 65.43W
CULEBRA 18.32N 65.28W

$$

VIZ001-002-220900-
/O.CON.KNHC.TR.W.1009.000000T0000Z-000000T0000Z/
/O.CON.KNHC.HU.A.1009.000000T0000Z-000000T0000Z/
1100 PM AST SUN AUG 21 2011

ST-THOMAS-AND-ST-JOHN 18.33N 64.85W
ST-CROIX 17.74N 64.73W

$$

ATTN...WFO...SJU...
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to the experts,if irene weakens some what going over land, will it take a more westerly track?
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Edit: Farther East.

Member Since: July 15, 2006 Posts: 17 Comments: 10159
5339. Buhdog
MY god Irene is HUGE.
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Big friggin ouch on this advisory
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I think NHC is late because they are talking to countries about update to Hurricane Warning.
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wow.......
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5335. reid221
11 PM 70 mph .. shift east .. 993 mb
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She's still a TS per the forecast advisory...
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crap...even our local on the 8s say tropical weather for sat...new updates...at 70mph...new cone too...shift to the right
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send in the bears
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Quoting NCHurricane2009:


Me too! and the blog will under go major-RI mode as Taz would say...


Yes, the blog will go nuts if its a hurricane...but, that could be offset if the cone shifts east and barely includes South Florida.
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70 mph, moving 285. 993mb
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Quoting MississippiWx:
Since the advisory is not yet out, I'm willing to bet they are about to upgrade to a hurricane.


The advisory will be reposted around 40 times if not upgraded over 100 if they do upgrade IRENE.
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5327. WxLogic
00Z NAM @84HR

Note TROF / High locations and strength in CONUS

Member Since: August 14, 2008 Posts: 4 Comments: 4927
5326. HadesGodWyvern (Mod)
Dvorak 3.5

60 kts for AL092011
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Quoting TampaCat5:

ULL? Where?


Yes, please show me where in a graphic...
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I remember Hurricane Irene back in 1999 dropped a lot of rain on South Florida. I had waist-high water in front of my home and koi fish swimming all around. History may repeat itself 12 years later it sees.
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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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