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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5023. Thrawst
Quoting Grothar:


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


Speaking of skinny islands....

http://www.youtube.com/watch?v=8wHMaJ6AtNs
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Quoting P451:
Interesting that this fix would be "due west" of the previous fix by recon.... for that would not line up with radar imagery which continues to show a steady WNW movement. The previous fix lined up with the radar imagery which is indisputable now. This one doesn't.

*shrug*



Remember that radar is probably not capturing the surface position of the center, only the mid levels. Would suggest that the mid levels are offset to the NE of the surface low center.
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Quoting TexasGulf:
If I were in the Bahamas right now, I'd be battening down the hatches. The Bahamas will be on the East side of circulation and should get the worst of the winds and storm surge.

If Irene goes just North of Hispaniola, the hurricane might become stronger than anticipated, meaning a more northerly track. That would be to the right side of guidance... or Bahama bound. Better safe than sorry.
Things are pretty slow here right now. Between tomorrow and Tuesday there'll be more hype. People buying food and plywood and stuff.

Member Since: October 25, 2005 Posts: 19 Comments: 22073
If you all have not looked at the Channel 2 loop you need to take a look.........WOW
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5019. amd
Quoting philliesrock:
lol am I seriously the only person seeing the NW jog? Everybody else thinks it 's to the W or WNW or something.


i thought that i saw the same thing, but recon is confirming that Irene is barely gaining any latitude. It looks like in the next vortex message that Irene has gained about 0.05 degrees north latitude or less, and has moved 0.30 degrees to the west
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Quoting atmosweather:


If you haven't taken notice, the hurricane hunters continue to find a steadily strengthening storm that is on the verge of becoming a hurricane.


Not for long...
Member Since: October 26, 2003 Posts: 0 Comments: 363
5017. JLPR2
Got power back again, but considering how everything is outside, it's just temporal. :\

Really windy now, but still under TS strength.
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Quoting RukusBoondocks:
IF the gfdl model doesnt start shifting to the right soon there could be problems with the west coast of FL


How soon? 12 hours, 24 hours, 48 hours?
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5015. 900MB
Quoting TropicalAnalystwx13:
Recon supports a 70 mph Tropical Storm.


So far.....
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5014. Dakster
Can we at least wave goodbye to Harvey?
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Quoting MiamiHurricanes09:
Yup, and I'm pretty sure that's what the NHC is gonna go with at 11p.m.


No pressure drop on this fix (maybe 1 mb) but the winds are catching up to the pressure falls of the last 4-6 hours.
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interesting...
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Quoting Grothar:


I know some people criticize us for posting those waves off of Afric when there is an active system close to home, but I always like to look ahead.


I think this is a good practice. There is room enough on this blog for more than one Area of Interest.
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5010. Patrap
Quoting weatherwart:


Dang, that's a big storm. Looks like good outflow. How are you doing, Patrap?


Sippin a FRESCA and watching the Spinning Yellow and red swirly thingee on da screen here.
Member Since: July 3, 2005 Posts: 423 Comments: 128236
Quoting RukusBoondocks:
who here thinks Irene will ride up the west coast of FL?


The noodles do not show that.
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Quoting weatherguy03:


You can wait until Tuesday, by then the track will be more certain for Florida.


I would considerb avoiding heavy rain which will affect us all over the place in FL,
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Quoting kmanislander:
Due West on the center fix. Waiting for dropsonde for pressure.
yes, last time dropsonde showed lower pressure than extrapolated strangely enough.
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Quoting RukusBoondocks:
who here thinks Irene will ride up the west coast of FL?


Me.
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Quoting gbreezegirl:
Where you at in gulf breeze?
IN proper or inside City Limits
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Over 5000!
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Time: 01:59:00Z
Coordinates: 17.8667N 65.3167W
Acft. Static Air Press: 843.5 mb (~ 24.91 inHg)
Acft. Geopotential Hgt: 1,443 meters (~ 4,734 feet)
Extrap. Sfc. Press: 993.7 mb (~ 29.34 inHg
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Member Since: August 2, 2010 Posts: 21 Comments: 9814
Due West on the center fix. Waiting for dropsonde for pressure.
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5000. 900MB
Quoting philliesrock:
lol am I seriously the only person seeing the NW jog? Everybody else thinks it 's to the W or WNW or something.


I see it a tad. Looks like it is going in a few miles south of Vieques and will hit PR on SE coast. Will probably cut a 2/3 slice route through PR.
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Quoting Chicklit:


You are about to catch it. How's prep been going on P.R.?

Well, my main concern has been my sato puppy. She's safely inside now. I also have a Shih-Tzu (4 cute years)but she lives inside. Also, a lot of chairs, tables and potted plants have been stuffed in the back garage. Windows are sealed, and I'm far from flood zones. Can't say the same for my school though.
Member Since: July 7, 2010 Posts: 0 Comments: 5681
4997. Dennis8
Quoting P451:


The difference between "just a tropical storm" and a serious tropical storm is the wind field.

One look at Irene's wind field tells you it is a serious tropical storm.

This is not a storm where they just barely found a 60mph wind in one quadrant away from the center - while the rest of the storm is a 30mph breeze.

No, this is a very solid strong wind field extending up to 150 miles outward with 40kt+ winds in all directions except the SW which only goes out about 75 miles.

That is a HUGE and serious storm.



IF this is huge what was IKE w/ TS winds 500 miles across???? Hurricane winds 200 miles across? Lets calm down.
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Quoting Patrap:
Unenhanched IR



Dang, that's a big storm. Looks like good outflow. How are you doing, Patrap?
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SFMR Peak (10s) Sfc. Wind: 66 knots (~ 75.9 mph)
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Quoting P451:


While it's not immediately flagged they can and do go back and review the data and would probably flag this.

Look at the rain rate accompanying it.


Regardless Irene is on the verge. I would suspect 70mph TS at 11PM.




Agreed... btw, can anyone post the updated models from 00z? Thanks!
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I can hear the keyboards clicking away at the NHC all the way up here in St. Augustine!
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993.4 mbs
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Just wait and see now.
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Quoting TropicalAnalystwx13:
Recon supports a 70 mph Tropical Storm.
Yup, and I'm pretty sure that's what the NHC is gonna go with at 11p.m.
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4988. Dennis8
EYE GOING DUE WEST
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4987. emcf30
Quoting MrstormX:


lol...you are having a double rainbow incident.


LOL
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lol am I seriously the only person seeing the NW jog? Everybody else thinks it 's to the W or WNW or something.
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Anyone applauding for a Hurricane has some real issues in life......Sorry for your existence!
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who here thinks Irene will ride up the west coast of FL?
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Recon supports a 70 mph Tropical Storm.
Member Since: July 6, 2010 Posts: 113 Comments: 31993
Hi folks. I saw a post on here earlier about a tornado striking Goderich Ontario (a community on the shores of Lake Huron). I don't want to go offtopic here, but I just wanted to say initial damage estimates are high end F2/low end F3 - 240 to 250 km/hr (Canada still uses the traditional Fujitsu scale, not the EF scale the US does).

Initial damage estimates here.

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Quoting Orcasystems:


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


See that -- not too happy about it. The shutters have lots of spiders in them!
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IF the gfdl model doesnt start shifting to the right soon there could be problems with the west coast of FL
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This is going to be one long week.
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UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 22 AUG 2011 Time : 011500 UTC
Lat : 17:56:42 N Lon : 65:26:06 W


CI# /Pressure/ Vmax
3.3 / 996.9mb/ 51.0kt


Final T# Adj T# Raw T#
3.3 3.5 4.0

Center Temp : -74.9C Cloud Region Temp : -65.7C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
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4976. Grothar
Quoting cycleranger:


Gro looking "upstream"...scarily like we're the Fish looking into the maw of a big ol' Bear.


I know some people criticize us for posting those waves off of Afric when there is an active system close to home, but I always like to look ahead.
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Quoting ecflweatherfan:
IDK, but it seems like motion based on radar seems to be between 275-280 degrees, not so much 285. It will be interesting to see where the HH spot the CoC on this pass. Still thinking the long trek across PR (the length of the island). I mean, Irene wants to visit PR... who can blame her, I have heard it is beautiful there. Hope all that are there are "hunkered down".
did someone call? :)
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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.


If you haven't taken notice, the hurricane hunters continue to find a steadily strengthening storm that is on the verge of becoming a hurricane.
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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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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.