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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Wow, 6Z GFS pushed a lot East. I know can't put any faith in one model run, but this has been a trend. Is the strengthening of Irene faster than anticipated, plus the lower anticipated land interaction causing this? I am also reading that the high is anticipated to be STRONGER, how does this jive with the further east tracks?
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7072. WxLogic
Quoting justalurker:


depends on her speed too.


Indeed... out running the building High.
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Quoting nash28:


They have both shifted a bit east of where they were for several days. Having said that though, they are still the outliers.
not saying which will turn out to be correct, but the same could be said for the models that have her farthest to the East
Member Since: August 15, 2008 Posts: 0 Comments: 2515
We went to bed last night thinking our "Hurricane deductible account" might stand a chance of staying in the bank. This sytem reminds me of Jeanne, I had looked out the window as it crossed over us and said "I have seen worse thunderstorms than this" and immediately lost power for eight days. Lesson learned!
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7069. WxLogic
Quoting hurricane23:
06z UKMET & GFDL are still over sfl this morning.


They're quite persistent at it.
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7068. rod2635
Quoting bwi:
Looks like 6z GFS also stays offshore until nearly up SC -- Cape Fear. Agrees with ECMWF, and has N or NNE motion after.

A track slightly west of the new GFS and ECMWF would have the post-landfall tropical storm or remnants coming right up the large east coast cities, affecting Richmond, DC, Philly, NYC with strong winds (and possible power outages).


Regrettably my concern as well. This far out a guess, but Myrtle Beach area landfall, followed by a trip up the coast would dump heavy rain on already saturated ground. Have properties on NJ shore and in Philly area. More concerned about Philly since we've had record rains this month, near 13 inches. Any rain along with tropical force gusts will send trees down. Same thing happened with Floyd where we recd 8" rain, 40 mile gusts resulting in a massive tree falling on our house. Would not care to see a repeat of that, but suspect conditions plausible for it to happen with Irene.
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Quoting WxLogic:


Is possible specially if it shifts further offshore (away from the islands) eroding the W periphery of the Bermuda High more than expected, which could buy it enough time to recurve before the High builds back up.


depends on her speed too.
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7066. jfm1975
Good Moning everyone. I just read a lot of the posts. I can tell you this. I am getting the same sick feeling I had before andrew and Wilma. People of south florida.This will bd one ti remember
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7065. WxLogic
Quoting OracleDeAtlantis:
She's pumpin' the ridge ...? I think we heard and saw that last year, in at least one case.


Hmm... you know, I believe IKE was did that (it was a rather intense HURR while in the ATL).
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Quoting StormJunkie:


Yeah, now that she has just escaped most land masses it appears; they will be on this like white on rice...Unless of course we're talkin' red rice...Yum.
Wow, way to remind me that I prolly will be eating more fire engine [steamed corned beef and white rice] than the law allow over the next little while.... lol

Member Since: October 25, 2005 Posts: 19 Comments: 22728
Im having some trouble modifying my comment. (I am talking about 120 hours out not now...
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9/1/0
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7061. nash28
Quoting hurricane23:
06z UKMET & GFDL are still over sfl this morning.


They have both shifted a bit east of where they were for several days. Having said that though, they are still the outliers.
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My forecast straight from NWS..

Friday: Hurricane conditions possible. Showers and thunderstorms likely. Mostly cloudy, with a high near 89. Chance of precipitation is 60%.
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06Z HWRF so far trending further east.
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7058. WxLogic
Quoting sporteguy03:

Interesting, so it could cause the gap North of it to close smaller?


It should actually get smaller as the TROF/weakness departs in a day or so. Which is why models bring it closer to the US coastlines.
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Quoting WxLogic:
Notice the following:

Weaker Irene (6HR ago):



HURR Irene (Current, but to update 1HR or so):



It could intensify the Bermuda High further as it moves in tandem with it towards the WNW.
She's pumpin' the ridge ...? I think we heard and saw that last year, in at least one case.
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Quoting WeatherNerdPR:
Really rough night, winds seemed to be near 60 mph at my house. The center of Irene passed just west of me. Still gusting to 40 - 50mph here.


Glad U OK!!
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06z UKMET & GFDL are still over sfl this morning.
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7054. scott39
Quoting charlottefl:



Just a fancy way of saying its the point where the winds at the mid latitudes and the outflow from Irene meet..
How long do you think it could hold the high at the mid to low levels, when it gets closer to Fl. Ive got Ederley family in Palm Bay Fl. 600 miles away, and I trying to get a better grasp on the NHCs language. TIA
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Quoting weatherb0y:
How likely is that?


Not going to happen...
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Does anyone know how the NHC comes up with the Wind Probability Table?
I only ask since there is only 6% chance of a Cat. 3, yet, they have have the winds at 110mph.  Seems like the actual chances should be higher if it only takes 1mph to make it a cat. 3.
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7051. WxLogic
Quoting weatherb0y:
How likely is that?


Is possible specially if it shifts further offshore (away from the islands) eroding the W periphery of the Bermuda High more than expected, which could buy it enough time to recurve before the High builds back up.
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Quoting mcluvincane:


She's going to be a record breaker. This one will go down in the History Books.
dont get ahead of yourself sign of panic she still might not get her name retired
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Oh no. My cousin went to Jr College in Jacksonville. Be bad if Irene came his way.
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Irene's pressure has fallen 20 MB's since Jeff's last update. lol - Time for a new one....?
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Quoting WxLogic:
Notice the following:

Weaker Irene (6HR ago):



HURR Irene (Current, but to update 1HR or so):



It could intensify the Bermuda High further as it moves in tandem with it towards the WNW.

Interesting, so it could cause the gap North of it to close smaller?
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Because it seems that Irene will now avoid hitting the Dominican Republic/Haiti, Irene will likely get stronger than projected. Therefore, any ridge weakness north of it may influence Irene more, so things are looking better for FL (although not out of the woods yet), but not so good further north (GA, SC, NC).
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7045. nash28
Quoting weatherb0y:
How likely is that?


That would indicate a much weaker High. Probably not that far east, but agreed.... That would be the best case scenario in what appears to be a major on the way.
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THE ECMWF...NOGAPS...AND GFDN MODELS
ARE THE RIGHTMOST OF THE NHC MODEL GUIDANCE SUITE AND KEEP IRENE
WELL EAST OF FLORIDA...WHEREAS THE UKMET AND THE GFDL MODELS ARE
THE LEFTMOST OF THE MODELS AND TAKE IRENE NEAR THE WEST COAST OF
FLORIDA. THE GFS AND THE REST OF THE NHC MODEL GUIDANCE IS TIGHTLY
PACKED BETWEEN THESE TWO EXTREMES AND TAKE IRENE THROUGH THE
BAHAMAS AND JUST OFF THE FLORIDA EAST COAST.
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Really rough night, winds seemed to be near 60 mph at my house. The center of Irene passed just west of me. Still gusting to 40 - 50mph here.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting charlottefl:
00ZLink CMC rides the entire SE US coastline...




its also initialized 200 mils south of where it is now. there is an increasing chance this storm never touches the us..
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Quoting WCSCTVCharleston:
\




Its ready to go I really think the NHC intensity forecast is very conservative
They always are! Expect a CAT 2 now.
Member Since: May 16, 2010 Posts: 0 Comments: 1472
Quoting WxLogic:
06Z NGP... whole US coast is spared. Good solution.
How likely is that?
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7039. WxLogic
Quoting nrtiwlnvragn:
Our Hurricane Hunter blogger LRandyB is on this morning's flight.


Nice to have bloggers that are close to the action.
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RSO Loop about half the loop is dark, but refresh every 10 minutes of so and it will fill in.
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7037. WxLogic
06Z NGP... whole US coast is spared. Good solution.
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7036. nash28
Having a hurricane prep meeting this morning at work. Most of the folks I work with have never been through a hurricane before..
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You can go out to 225nm on that radar site:


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Quoting BahaHurican:
Hey, Tboy... was wondering we hadn't seen u a day or two...

Quite a few of those comments are likely to be from pple in the actual forecast area... dunno how well they'll hold up to the pple posting "Eeeek!!!!" over and over again, though.... lol



business will be a boomin today....as it should....this hurricanader looks like it means business!!
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Quoting bwi:
Looks like 6z GFS also stays offshore until nearly up SC -- Cape Fear. Agrees with ECMWF, and has N or NNE motion after.

A track slightly west of the new GFS and ECMWF would have the post-landfall tropical storm or remnants coming right up the large east coast cities, affecting Richmond, DC, Philly, NYC with strong winds (and possible power outages).


She's going to be a record breaker. This one will go down in the History Books.
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7032. QMiami
Quoting BahaHurican:
Ya'll, all I gotta say is P541 and Drak have been ON with this... Looks like Irene is exiting the coast not too far from Levittown, which is west of San Juan. Any of our PR bloggers still online? Was wondering how badly power grids have been affected....


not from PR but earlier discussion had said 800,000 without power
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Recon are wheels up...
Member Since: October 25, 2005 Posts: 19 Comments: 22728
Our Hurricane Hunter blogger LRandyB is on this morning's flight.
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Last view of the nice eye Irene has, we could get a major later today, not likly but possible.

Link
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7027. scott39
If your in Fl. and not getting prepared right now...then lawd help ya!
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We have Take Off

Time: 10:50:00Z
Coordinates: 17.7N 64.75W
Acft. Static Air Press: 961.5 mb (~ 28.39 inHg)
Acft. Geopotential Hgt: 409 meters (~ 1,342 feet)
Extrap. Sfc. Press: 1006.3 mb (~ 29.72 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 170° at 28 knots (From the S at ~ 32.2 mph)
Air Temp: 23.9°C (~ 75.0°F)
Dew Pt: 23.3°C (~ 73.9°F)
Peak (10s) Flt. Lvl. Wind: 29 knots (~ 33.3 mph)
SFMR Peak (10s) Sfc. Wind: -
SFMR Rain Rate: -
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000
WTNT64 KNHC 220958
TCUAT4

HURRICANE IRENE TROPICAL CYCLONE UPDATE...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011
550 AM AST MON AUG 22 2011

CORRECTED TIME IN DATE/STIME HEADER

PRELIMINARY REPORTS INDICATE THAT WIDESPREAD TREE AND POWERLINE
DAMAGE HAS OCCURRED ON PUERTO RICO...AND MORE THAN 800 THOUSAND
HOMES ARE WITHOUT POWER ON THE ISLAND.

ALSO...FAA DOPPLER WEATHER RADAR INDICATES WINDS TO NEAR MAJOR
HURRICANE STRENGTH ARE NOW OCCURRING IN THE HIGHER ELEVATIONS OF
THE INTERIOR MOUNTAINOUS REGIONS OF PUERTO RICO.

$$
FORECASTER STEWART
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Woke up with a hurricane and the new NHC track will bring it into GA, possibly as a major hurricane.
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Quoting scott39:
What is upper-level mass confluence. TIA



Just a fancy way of saying its the point where the winds at the mid latitudes and the outflow from Irene meet..
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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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