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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I figured somebody on here would know where to look for this. On the NHC site's 5-day cone graphic, there used to be an animate button that would show where previous cone tracks had been in relation to where it was in the most current update. Does anybody know if they ditched that feature or if I'm just missing it somewhere on the page?
(I liked to see how the cone moved from update to update as they got more confidence in the track.)
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Quoting Bluestorm5:
Sorry... my parents are being a-hole to me. I'll come back later.


that's our job
Member Since: August 13, 2007 Posts: 0 Comments: 10484
4271. scott39
Quoting scott39:
I think after Irene had the N center relocation early this morning, the models had no choice but to shift E. the NHC KNOWS that anything can change, especially out after 3 days. Thats why thier not out in the SE Atlantic with the middle track yet. Thats why the cone is in the Eastern GOM and in the SE Atlantic. They leave that room for a very good reason....Mother Nature
Quoting ProgressivePulse:
Models coming back west a tad, TVCN slightly west.

I think Irene is moving only slightly N of due W now. Maybe that is what is in play. I think Irene is going to be a nail biter to landfall.
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Quoting 7544:
did the models just shift west again



alittle
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Quoting 7544:
did the models just shift west again


Yes, a little bit. I have a feeling the NHC held their track @ 5pm for a reason.
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Reed Timmer
Reported large tornado has just destroyed the town of Goderich, Ontario.. More soon
44 minutes ago

Via Twitter
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Quoting breald:
I just down loaded google earth to my laptop but cannot pull up the models. Is there something else I should download?


Go to http://tropicalatlantic.com and click on Recon There is a kml file you need to download to view the HH flights on Google Earth.

You shall be soon addicted! :)
Member Since: June 1, 2007 Posts: 0 Comments: 886
Quoting WCSCTVCharleston:


2 troughs, thats right. I guess it all depends on how far south the next one digs. But to expect a deep system after land interaction? We've seen the opposite plenty of times..
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Quoting serialteg:


been like that for a wile now... calm before the storm. east coast's not like that tho
will you be out in the storm like you were in Emily, giving us reports?
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4263. Levi32
Quoting scooster67:
Levi,

Is dry air prohibiting the West side from closing off its eye completely?

If so

Do you think it will pull the convection from the North down over the west and cut the dry air off?


Yes the dry air that Irene has been dealing with today is probably not helping the southwest eyewall, though of course most tropical storms don't have a closed eyewall. The center will always look for a way to wrap the convection around the center, so yes we could see some of the bands from the north try to connect around the west wide eventually.
Member Since: November 24, 2005 Posts: 635 Comments: 26601
Quoting weatherman12345:
does that change anything in terms of track if it slows down abit
levi your tidbits this am and yesterday talked about such a scenario -based on the my opion is a flagler beach to vilano beach landfall do you agree ???
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Quoting hotrods:
Looks like the TVCN model is staying put along the east coast Fl.



Slight westward shift 00Z. NHC should maintain their current track @ 11pm.
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Quoting JRRP:
definitivamente looks like hurricane..


11PM will likely be upgraded to a minimal category one hurricane. IMO
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Can anyone tell me if this would be the right steering layer for Irene? It's the 500-850 mb. layer...TIA






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4256. 7544
did the models just shift west again
Member Since: May 6, 2007 Posts: 0 Comments: 6772
Quoting WeatherNerdPR:
It suddenly got quiet...creepy.


been like that for a wile now... calm before the storm. east coast's not like that tho
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I dont see Irene a MH. Any one?
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Quoting clwstmchasr:


700-750 miles off in 5 days. I don't believe that is their error guidance.



More like 250-500 miles
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4252. xcool
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Radar shows trying to close a cloud wall around what appears to be a very small COC. It can be seen just off the extreme NW tip of st croix. Thats where the center fix came from Recon.
Member Since: August 22, 2010 Posts: 0 Comments: 652
4250. msphar
Two hours ago Fajardo reported a gust to 41 Kt. Fajardo is typically a windy place. It is currently reporting 28 Kts. NNE with gusts to 34 kts. This does not seem significant.
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Just as a point of interest, a line from the most recent vortfix at a heading of 285, Irene's current heading, would drag the centre along the north coast of Hispaniola, entering north of Puna Cana and exiting between Cap Hatien and Jean-Rabel. Since Irene is not likely to be more than a cat one at that point, I'd expect that amount of land interaction to have at least a short-term impact on it, even though the terrain is much less rugged than it is to the south.
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Quoting Patrap:
00z Irene Early Cycle NHC model tracks
Irene Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)



Dynamic Models (More sophisticated models)








so...You just had to go and post this right after I told Charleston people to chill, huh?!?!?!
Member Since: August 13, 2007 Posts: 0 Comments: 10484
Quoting P451:
17.85N, 65W - Center located below. (green)






The dry feature (circled purple) that was followed on radar imagery the past 3 hours which had an apparent wsw motion was rotating around the circulation center.

The true surface circulation has continued on a WNW motion.

PR is in a bit of trouble with this one now.

Large wind field, intensifying system, hot towers exploding over the center.



i got 2 energy drinks, 6 bags of ice on the freezer (power's still on), 400W inverter hooked up to the car battery, lots of water stored, gas stove check, light sources check.

gonna blog and post videos today - a puerto rican version of Oz lol
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Quoting scooster67:
Levi,

Is dry air prohibiting the West side from closing off its eye completely?

If so

Do you think it will pull the convection from the North down over the west and cut the dry air off?


Some are suggesting land interaction to the west.

Could be that and not the dry air.?
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Knew the Hurricane Irene was JFV, he made Hurricane Emily when the beloved storm was alive.
Member Since: September 2, 2006 Posts: 110 Comments: 6876
It suddenly got quiet...creepy.
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4243. breald
I just down loaded google earth to my laptop but cannot pull up the models. Is there something else I should download?
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4242. Levi32
Quoting atmosweather:


Good evening Levi hope you're doing well! She has definitely slowed some from earlier today. Just got back from work and I see from the San Juan radar that she has about 40-50% of an eyewall complete, RECON finding plenty of 60-65 mph winds too. I'd say a Category 1 hurricane is becoming likely by the time she reaches the SE-ern coast of PR. Do you agree?


Hey Rich. It is possible she runs close to minimal hurricane status as she moves into Puerto Rico if the current rate of deepening continues. Certainly before Hispaniola she should be a hurricane.
Member Since: November 24, 2005 Posts: 635 Comments: 26601
Quoting FISHHEAD4UFl:
Can someone answer me please lol..... why is nhc shooting through florida still when most models are east of florida

"This storm is expected to slow down and weaken significantly after interacting with the mountainous terrain of Hispaniola. How the storm behaves after it passes Hispaniola and Cuba is uncertain. It depends on how much land mass interaction takes place.
**NOTE: if the storm misses these high terrain islands, it has the chance to strengthen much more than forecasted at this time.

The new models are trending further east which is a good sign for us. BUT, this trend needs to continue for a few model runs before we can think that solution is possible."
From: http://www.wptv.com/dpp/news/tropical-storm-irene- forms-near-the-lesser-antilles
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Quoting WeatherNerdPR:

I'm ready. We barely prepared for Jeanne, and we got no structural damage. I doubt it'll be any different with Irene.
P.S. I didn't mean to offend you Irene, so don't get ticked off and destroy the island.


LOL.
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Quoting WCSCTVCharleston:
Again I cant even remember the amount of times a storm this far out has Charleston SC in its path and it always goes to nc or out to sea


Wait for the next model suites,or the following,Irene is going to visit Florida,just as the models have been predicting for 2 weeks almost,these center re-location gig change the track forecast in short term, but when all is said and done,it's gonna be Florida. JMHO
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4236. Patrap
00z Irene Early Cycle NHC model tracks
Irene Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)



Dynamic Models (More sophisticated models)





Member Since: July 3, 2005 Posts: 423 Comments: 127814
Quoting FLweather:
Haven't the models depicted this trough to move out rather quickly? It doesn't look like it is going to keep diving directly south. When you watch the WV loop it looks like it is already starting to level out, let alone moving extremely fast. By the looks of it, this trough will be gone before we know it. Pay attention to Michigan in particular, it is retreating. I'm no expert and this is just my own opinion. But I recall stating last night that Irene was an imminent threat to PR and would have trouble avoiding a direct hit with the island. That's not even taking into account what the effects of a direct hit would cause...weakening, decoupling, reorganizing in a different area? Idk, JMO.

There are going to be 2 troughs first slows it down 2nd one turns more nw to nnw especially if Irene is a deep system after its trek across the islands.
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4234. 7544
looks like shes moving west again but a bit slower and building
Member Since: May 6, 2007 Posts: 0 Comments: 6772
Quoting leelee75k:


because a hurricane or storm isn't a skinny line or dot on the map and any slight deviation of the track could put the worst weather back over Florida.


Or take it out into the Atlantic.
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4232. hotrods
Looks like the TVCN model is staying put along the east coast Fl.
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What computer model proves to have been most accurate in the past? I believe it is the GFDL is the one most relied upon correct? That would explain why the NHC still has the forecast track on more to the west then to the east, yes?
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Irene's center could be affected by PR. Not much I would say. Looks like SC landfall or so. Who knows. Yesterday it was the GOM.
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4227. snotly
is that a weak ULL over Cuba?
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Quoting Levi32:


They tend to avoid flinging their long-term track in the direction of a sudden model swing, in case the models just flip back the other way. They may also have a reason or two for staying west of the models. If the 0z models stay east of Florida, chances are their track will shift farther east, closer in line with them.
thankyou :)
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Quoting PRweathercenter:



Well, moreso now. You have a strengthening core baring down on you ATM.
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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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