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 tiggeriffic:


i mentioned earlier that the mets on tv were saying it looked more like a hit north of hispanolia and was slammed for it...hope they don't do the same to you...


Thanks........LOL.......i have a hard shell hat!
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This pass should show a due west movement,or does Recon lie?
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4971. Patrap
Unenhanched IR

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Where you at in gulf breeze?
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NOTE!

The feature which is 98L will help to moisten the atmosphere for the next wave that is about to come off Africa. I think this wave is going to be the next big threat later down the road and some models even show it blowing up in a few days. We will have to watch it.

Link
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Irene is landfaling in Vieques right now...
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993.5mb. Let's see if we got a dropsonde.

015930 1751N 06520W 8428 01453 9935 +211 +176 277008 010 018 001 03
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4965. mrjr101
Quoting MrstormX:
Borderline cat 1, will be at the forecasters discretion.


Cat1 because it's PR, how much you want to bet?
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Quoting killdevilmax:
The drama on here is great entertainment. Gave up tv tonight for this blog. Yo Taz




hi killdevilmax
Member Since: May 21, 2006 Posts: 5091 Comments: 115362
I've seen several posts about "its only a tropical storm".

A tropical storm that is bouncing up and down between a cat 1 that is intensifying can cause a lot of trouble. When Katrina came across South Florida it was "only a tropical storm", but was ramping up as it moved.

No power for several areas for 10 days, lots of roofs taken off, and major flooding. That's not exactly nothing.

You should always be prepared for at least one category more than its forecasted, especially for those of us who live right off of those 90 degree waters.
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4962. NCSCguy
Quoting tiggeriffic:


you'd have to do it before the winds start...but have even seen those viaducts close on down 61 before...took us 9.5 hours to get from West Ashley to Summerville going the back way during floyd
Well I have never been in a hurricane before (except Hugo, but I was 2 so I don't remember that). But I hear that evacuation is a nightmare and I am totally not looking forward to it.
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4961. 900MB
Quoting kmanislander:
A whole page of contaminated winds over 70 mph.

Center fix shortly


Kman-
What do you mean "contaminated"? Effect of rain? Barbs before and after were 50's and 55's, so you figure it is plausible?? Or at least close.
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Quoting Grandpato4:


Yes, they are monitoring the situation and my property will be one of the first they secure should the storm be heading that way.
Glad to hear this...

@ Detrina... we've had carolinacasters practically since the start of the blog.... and definitely since 2006... lol
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Quoting emguy:
From an Irene standpoint...I'm really not all that impressed with the current shortwave trough moving through the eastern US. It kinda looks flat and looks like it may be starting to pull to the NE already.

Later down the road as Irene moves into the next weakness (break in ridge), the Bermuda high will be building back in, so I am a little speculative of the models showing an almost due north coast to the Carolinas. NW seems to be a better fit. It just seems too sharp for the pattern, especially if the "ridge bridge", better known as a "wrap around high" does develop later on. Special note on the "ridge bridge" otherwise...this could potentially slow a storms forward speed, which could increase flood threats in impacted areas of the US.


and allow it to gain strength
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Quoting Grothar:


Are you on Viegues, that small skinny island to the East of Puerto Rico?

Vega Alta(North-Central PR). Very little rain, but gusty winds have almost made me loose power countless times.
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4957. msphar
Esperanza 12 Kts. ENE gusting 26 Kts
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!!!!woooooo yah fireworks!!!First hurricane!!!!fireworks.
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Quoting mcluvincane:
Hurricane Irene has arrived I see



no it has not
Member Since: May 21, 2006 Posts: 5091 Comments: 115362
Quoting WeatherNerdPR:

Squalls should hit me soon.


You are about to catch it. How's prep been going on P.R.?
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4953. MahFL
Hurricane at 11 pm ?
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4952. Patrap
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4951. jonelu
Quoting Grothar:


Very close. Very, very close. Depends on how strong that trough will be. If it stay more W-NW. It could be very close to SE Florida and move very slowly. Iam more concerned about that than the category at this time.
Why do you think she will be going slow?
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Quoting MiamiHurricanes09:
Holy Jesus! 66 knot SFMR winds in the northeast eyewall:

015430 1806N 06514W 8446 01465 //// +142 //// 113060 062 066 040 01

Pressure down to 994mb and they haven't reached the circulation yet:

015830 1754N 06519W 8435 01440 9940 +193 +188 082010 011 022 001 03


That is like 76 MPH. Thinking we have Hurricane Irene now.
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Quoting P451:


And replaced Rita with Rina.

:|

It's nothing less than asking for trouble, and possibly treasonous. This bs started last year, with Igor. Who taunts a storm by calling it Igor. Do we expect a storm named Igor to go quietly in the night, like Harvey?
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Quoting Dakster:


Hey, you get to watch Darwin at work...
Link
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The drama on here is great entertainment. Gave up tv tonight for this blog. Yo Taz
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Quoting barotropic:


You keep on saying thing like Motoring atc. But....there is no motoring here. If you havent taken notice, Irene really isnt looking good, is full of dry air and the small COC which just recently developed is slowly expanding again. and you keep saying wnw.....when its, at least for the most part maybe N of due west. The COC is about in line with the S coast of puerto rico and has been for the most part for hours. There is no "Motoring" . If you measure precipitation under storm total and or 1 hour total....there is practically no expansion with time....cause not a whole lot of motion either way is going on. Frankly from a radar presentation standpoint I have seen a strong depression look better.


I like it!
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4943. Grothar
Quoting WeatherNerdPR:

Squalls should hit me soon.


Are you on Vieques, that small skinny island to the East of Puerto Rico?
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Quoting KEEPEROFTHEGATE:


Man that ridge really builds back toward the east coast/florida.Do you have the current and how does it compare to the 19th?
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Long night ahead of pressures have fallen enough and winds are at Hurricane force by 11 PM. More problematic is the slowing of the system leading to greater rainfall across Puerto Rico over the next 12-24 hrs.
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TD.Harvey_12amGMT_ATCF : Starting 21August_12amGMT and ending 22August_12amGMT

The 4 short line-segments represent TropicalDepressionHarvey's path
and the westernmost line-segment is the straightline projection.

Using straightline projection of the travel-speed&heading derived from the ATCF coordinates spanning the 6hours between 6pmGMT then 12amGMT :
TD.Harvey's travel-speed was 12mph(19.3k/h) on a heading of 305.1degrees(NW)
TD.Harvey was headed toward passage over Tuxpan,Veracruz(state) ~18&1/3rd hours from now

Copy&paste 17.3n89.6w-17.5n90.7w, 17.5n90.7w-17.9n92.0w, 17.9n92.0w-18.4n93.3w, 18.4n93.3w-19.0n94.2w, tam, 18.4n93.3w-21.02n97.33w into the GreatCircleMapper for more info

The previous mapping (for 21August_6pmGMT)
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Quoting MiamiHurricanes09:
Yeah, and flight level winds are a little below it. Nevertheless, I really didn't consider it suspect since they were SFMR winds in the 60 knot range.
Very close to hurricane strength. The northern band they flew through is quite intense.
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Quoting zoomiami:


Wondered where you were!


I'm here... your going to get wet :)
Just updating the HH data as it comes in... if this thing passes North of PR/Haiti (which I hope it does, they have enough problems).. your going to get hammered
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Hurricane Irene has arrived I see
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we all most have are 1st hurricane
Member Since: May 21, 2006 Posts: 5091 Comments: 115362
Quoting MrstormX:
Borderline cat 1, will be at the forecasters discretion.

For the sake of the blog, just make it a hurricane!
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting FLdewey:


Great post. I'm thinking she'll miss us to the east, which is fine by me. This of course is based on no scientific data, but it has the same chance of being correct. ;-)


Hey at least your honest enough to admit its not based on scientific data :)


As for me, I'm going to school for this stuff so, everything I bank on is based on real scientific knowledge haha.


Anyways, I'm leaning toward a more right path too, and did form the start, however in all honesty, I would almost want to see a category 1 hurricane make landfall here in Tampa Bay, because for one it would be quite exciting, yet not devastating, yet scary and strong enough to shake up residents to remind them that hurricanes do sometimes make landfall here as rare as it is, and that even a low end hurricane is powerful indeed!

I'm worried that there will be slaughter here in Tampa Bay if a high end hurricane plows into here. Many people not only ignore warnings here now, but they even literally believe foolish things like that there is some sort of government shield created by McDill AFB over the area, or a voodoo spell that keeps them away.

Stuff like that scares me, it makes me worry for people here when I here that people believe things like that and are so slow to heed warning.
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4933. Patrap
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Welp we have hurricane force winds and the data is not suspected.

Peak (10s) Flt. Lvl. Wind: 62 knots (~ 71.3 mph)
SFMR Peak (10s) Sfc. Wind: 66 knots (~ 75.9 mph)
SFMR Rain Rate: 40 mm/hr (~ 1.57 in/hr)
(*) Denotes suspect data
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4931. Dakster
Quoting FLdewey:


+100,000 ;-)

Irene is fidd'nin to blow up. DOOM:CON™ may be upgraded tonight... twice is one day. :-o


Does school start tomorrow in Central Florida?

Tomorrow is the first day back here in South Florida...
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4930. tarps3
Quoting cerespa:

Vieques


Thanks!
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Quoting gulfbreeze:
YES!@!!!!
??????????? Why? This meant high end major hurricane for East Coast.... *facepalm*
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Someone earlier made a comment about Irene stalling! What would be the chance of stalling before Florida?

New to this blog!!
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Quoting Grothar:
I know all eyes should be on Harvey and Irene, but this could be important next week.



Gro looking "upstream"...scarily like we're the Fish looking into the maw of a big ol' Bear.
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Borderline cat 1, will be at the forecasters discretion.
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4925. MahFL
Looks to me Irene will pass over the NE corner of PR. That would enable strengthening all the way to Florida...
Member Since: June 9, 2004 Posts: 0 Comments: 3706
Quoting P451:


Evening.


Motoring WNW. Steady as she goes.

Core looking better and better....but I wonder if it has a chance to fill in the rest of the southern side before PR.

Amazing how it ditched that large broad feature and a small tight circulation center popped out of the SE corner of it for us to see.



You keep on saying thing like Motoring atc. But....there is no motoring here. If you havent taken notice, Irene really isnt looking good, is full of dry air and the small COC which just recently developed is slowly expanding again. and you keep saying wnw.....when its, at least for the most part maybe N of due west. The COC is about in line with the S coast of puerto rico and has been for the most part for hours. There is no "Motoring" . If you measure precipitation under storm total and or 1 hour total....there is practically no expansion with time....cause not a whole lot of motion either way is going on. Frankly from a radar presentation standpoint I have seen a strong depression look better.
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this is fun
Member Since: May 21, 2006 Posts: 5091 Comments: 115362

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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.