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 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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5872. mbjjm
In the last nhc discussion , they mentioned the Fim model any info on this model , its the first Im hearing it.
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5871. 47n91w
MESSAGE DATE: AUG 22 2011 03:26:00

THE FAA SAN JUAN WSR-88D DOPPLER WEATHER RADAR (TJUA) HAS GONE DOWN...MOSTLY LIKELY DUE TO A LOSS OF POWER AT THE CAYEY RADAR SITE...AS RAIN BANDS ASSOCIATED WITH TROPICAL STORM IRENE MOVED ACROSS THAT AREA. WE ARE UNABLE TO RESTART THE RADAR AT THIS TIME AND FAA AOCC HAS BEEN NOTIFIED. RESTORATION TIME IS UNKNOWN.

Edit: Blog's moving fast, I apologize for the repeat.
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Quoting air360:


Please correct me if i am wrong but you mean since it initiated it farther south to begin with it is still showing it being more south?


There was nothing wrong with initiation. It just takes the track farther south and west so far.
Member Since: July 15, 2006 Posts: 17 Comments: 10244
Quoting P451:
Well... the power is still generally on in the major regions. Nothing large scale i is out.

last year I had wondered about the night side of this satellite image. I wondered about if this was a realtime image or not. From what I remember, it turns out the image of city lights is not realtime, but an image overjoyed just a google maps are...so those lights will must likely stay on the whole time as its not a true time picture...would be cool if it was real time though...
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Quoting NCHurricane2009:


You would think something as important as a radar would be on generator power or something...C'MON!
Yeah I was a little surprised about that.. guess they do things on Island Time there. It has been down for the past half hour now.
Member Since: September 19, 2004 Posts: 32 Comments: 6123
Quoting Drakoen:


I agree. Satellite and radar giving her a more westerly component.


It will be interesting to see how long this heading holds.

For me that's it for tonight.

See everyone tomorrow.
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Irene Vortex (8/22 03:41:30Z): MSLP: 989mb; Inbound Flt. Lvl. Wind (Item F.): 63kts (~72.4mph); Max Flt. Wind (from Remarks): 67kts (~77.0mph)
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Quoting Tazmanian:



yup now whats see what they find in winds


like before, winds take time to pick up in accordance to MB drops
Member Since: August 22, 2006 Posts: 2 Comments: 1983
Quoting PrivateIdaho:


I hope so for you sunline....or maybe 20.


Or maybe 10???.... I'm checking the conveyor belt....
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Quoting kmanislander:


Going down fast. 3 mbs in about 2 hours.


Never mind...I thought she was at 993 mb more than 2 hours ago....
Member Since: September 15, 2009 Posts: 473 Comments: 3668
5861. air360
Quoting MississippiWx:
So far the GFS is farther South.


Please correct me if i am wrong but you mean since it initiated it farther south to begin with it is still showing it being more south?
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5860. JLPR2
Lightning getting more frequent now.

Irene is attempting some rapid strengthening.
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Quoting Drakoen:


Yeah Sully, i've had that gut feeling too.


Wow, that can't be good, living in South Carolina now.
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Quoting MississippiWx:
So far the GFS is farther South.
Way farther! Hmmm.
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5856. HadesGodWyvern (Mod)
Philippines Atmospheric Geophysical Astronomical Services and Administration
Tropical Cyclone Bulletin #2
TROPICAL DEPRESSION MINA
11:00 AM PhST August 22 2011
=====================================

Tropical Depression "MINA" has maintained its strength as it moves north northwestward.

At 10:00 AM PhST, Tropical Depression Mina located at 13.7N 127.7E or 350 kms east southeast of Virac, Catanduanes has 10 minute sustained winds of 25 knots. The depression is reported as moving north northwest slowly

Additional Information
======================

Tropical Depression "Mina" is expected to enhance the southwest monsoon and will bring scattered to widespread rains over Southern Luzon and Visayas.

Estimated rainfall amount is from 10-20 mm per hour within the 300 km diameter of the tropical depression.

The public and the disaster coordinating councils concerned are advised to take appropriate actions and watch for the next bulletin to be issued at 11 PM tonight.
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5854. snotly
will all the convection north act to lower relative pressure and pull the storm north as it interacts with land?
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Quoting atmosweather:


By a lot.


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...
Member Since: September 15, 2009 Posts: 473 Comments: 3668
Quoting ChrisDcat5Storm:


thats slighty due north of west


The NHC consider 275 to be due West but technically just N of due West.
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Lightning is a potential sign of rapid intensification within a tropical cyclone. Lightning and rapid intensification have been in association with rapid strengthening like within hurricane Felix 2007.
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5849. luigi18
Quoting Gearsts:
Is a miracle that power is still on.

Yup power still up here in bayamOn
Member Since: September 21, 2008 Posts: 0 Comments: 481
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.

Member Since: July 15, 2006 Posts: 17 Comments: 10244
Shoulda just called it at 11 p.m.
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5846. Drakoen
Quoting sullivanweather:
I know many people here tonight that have been watching these things for years have that gut feeling this will be one of those fabled East Coast hurricanes.

I know I've had it for a number of days now. Atmospheric pattern resembles August 1955, which serves as a great analog month for this one.


Yeah Sully, i've had that gut feeling too.
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Quoting kmanislander:
New center fix still showing a track of about 275. Not currently WNW


I've been say'n
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Quoting MississippiWx:


Just had to pick my jaw up from the floor. Wow!


Going down fast. 3 mbs in about 2 hours.
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Quoting MississippiWx:


Just had to pick my jaw up from the floor. Wow!


IMO...its strengthening...but not that impressive of a pressure drop considering it was 993 mb hours ago...she'll either be upgraded to a 'cane in a special statement or in the post-storm analysis....
Member Since: September 15, 2009 Posts: 473 Comments: 3668
Quoting Relix:
Emily is a hurricane? Not surprising.
Emily is passing through PR? Not surprising.
That PR still has power? HOLY *^*^%#


That's the miracle of the Via Verde$$....
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Quoting MississippiWx:
So far the GFS is farther South.


By a lot.
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Satellite and radar showing a more westerly track.
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5838. tarps3
0z GFS Hr 48

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Well, lightnings here was just freaking out tonight. Never seen this much lightnings ever here... bad omen?
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Quoting MiamiHurricanes09:
Could be rapidly intensifying right before landfall. 989.9mb.

034130 1754N 06532W 8434 01414 9899 +214 +179 152003 009 017 000 00



yup now whats see what they find in winds
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Quoting kmanislander:
New center fix still showing a track of about 275. Not currently WNW


thats slighty due north of west
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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 *^*^%#

I know for sure I would of lost power, got to give credit to your power grids!
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So far the GFS is farther South.
Member Since: July 15, 2006 Posts: 17 Comments: 10244
Time: 03:41:30Z
Coordinates: 17.9N 65.5333W
Acft. Static Air Press: 843.4 mb (~ 24.91 inHg)
Acft. Geopotential Hgt: 1,414 meters (~ 4,639 feet)
Extrap. Sfc. Press: 989.9 mb (~ 29.23 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 152° at 3 knots (From the SSE at ~ 3.4 mph)
Air Temp: 21.4°C (~ 70.5°F)
Dew Pt: 17.9°C (~ 64.2°F)
Peak (10s) Flt. Lvl. Wind: 9 knots (~ 10.3 mph)
SFMR Peak (10s) Sfc. Wind: 17 knots (~ 19.5 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)
(*) Denotes suspect data
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5830. Drakoen
Quoting kmanislander:
New center fix still showing a track of about 275. Not currently WNW


I agree. Satellite and radar giving her a more westerly component.
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Quoting NCHurricane2009:


Well that's neat...that shows Irene has gone through two NW wobbles and a general WNW track since birth...one NW wobble occuring last night...another occurring today when it was by St. Croix...
It is a nice visual. What caught my attention was near the end. Irene's filling out on the southern side. imo of course.

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Could be rapidly intensifying right before landfall. 989.9mb.

034130 1754N 06532W 8434 01414 9899 +214 +179 152003 009 017 000 00
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Quoting GetReal:


Oh boy here we go. Blog explosion in 3...2...
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Quoting Rainman32:
NOUS62 TJSJ 220326
FTMJUA
MESSAGE DATE: AUG 22 2011 03:26:00
THE FAA SAN JUAN WSR-88D DOPPLER WEATHER RADAR (TJUA) HAS GONE
DOWN...MOSTLY LIKELY DUE TO A LOSS OF POWER AT THE CAYEY RADAR
SITE...AS RAIN BANDS ASSOCIATED WITH TROPICAL STORM IRENE MOVED
ACROSS THAT AREA. WE ARE UNABLE TO RESTART THE RADAR AT THIS TIME
AND FAA AOCC HAS BEEN NOTIFIED. RESTORATION TIME IS UNKNOWN.


You would think something as important as a radar would be on generator power or something...C'MON!
Member Since: September 15, 2009 Posts: 473 Comments: 3668
989.9 mb (~ 29.23 inHg)
17.9N 65.5333W
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I know many people here tonight that have been watching these things for years have that gut feeling this will be one of those fabled East Coast hurricanes.

I know I've had it for a number of days now. Atmospheric pattern resembles August 1955, which serves as a great analog month for this one.
Member Since: Posts: Comments:

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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.