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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1673. shawn26
If that is a pinhole eye and it is moving due west, it will go under Puerto Rico
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1672. robj144
Quoting atmoaggie:
Honestly, *could* be. But will Irene maintain it?



I don't think that's an eye. If it was, isn't that a rather small eye for such a weak system so far?
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Quoting atmoaggie:
Honestly, *could* be. But will Irene maintain it?


I think it'll keep popping it up as it strengthens, not really sustaining it until it reaches 70-75mph. Just a guess, though.
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Quoting Bluestorm5:
I have many friends who is Hurricanes' fans. They LOVE the name now and they call themselves, "Caniacs".



This is correct. Some of the best hockey fans in the country (obviously canada has better), and I myself am a CANIAC!!!

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Quoting Stormchaser2007:
Repost

18z models

Little bit of Hispaniola

FULL IMAGE



If it stays on the North/East part of Hispaniola, there's not too many mountains so disruption would most likely be limited
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Quoting tennisgirl08:
People on here are ridiculous. There is no eye, the storm is moving due west, and there is a lot of uncertainty with regards to track and intensity. No need to overhype this thing right now. Let it play out...


The radar from PR does indeed suggest an eyewall is forming. St Croix may not be a good place for the HH to "hunker down".
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1667. ncstorm
Quoting RyanFSU:
ECMWF 12z tighter zoom:



NC would be on the NE quadrant side of that storm..not good at all!!
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Quoting MississippiWx:
Sigh...I guess some are going to believe what they see, regardless if it's real or not.

I guess we have about 3 or 4 eyes in this new rapid scan frame:

Wow Irene is a four eyeded storm?
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Well, the GFS, ECMWF and HWRF have shifted well off the east coast of FL, good for FL (specially the West Coast) not so good nor GA, NC and SC. HOWEVER, the 12Z GFDL and NAM still shows a huge major hurricane still just off the WEST coast of FL. The GFDL hasn't done so well with this system so far, so I am believing the GFS more. The UKM is out in left field (literally) showing the storm heading toward the middle of the Gulf. So I guess for now I will shift (I am in the Tampa Bay Area) from panic mode to just watchful apprehension.
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Quoting tennisgirl08:
People on here are ridiculous. There is no eye, the storm is moving due west, and there is a lot of uncertainty with regards to track and intensity. No need to overhype this thing right now. Let it play out...
is it dry air?
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Quoting MississippiWx:
Sigh...I guess some are going to believe what they see, regardless if it's real or not.

I guess we have about 3 or 4 eyes in this new rapid scan frame:



The human mind is constantly trying to find order in chaos.
Member Since: August 29, 2010 Posts: 0 Comments: 5236
1660. ackee
IRENE does not have eye to me when look on IR can see its dry air seem like moving west
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1659. Gorty
Quoting Gorty:
Is New England a possible target from Irene? It almost looks like she could go south to due north into LI and then CT on north. New England will get wrecked by a major. I live in New England.


Anyone? lol
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Quoting StormJunkie:
All of the 18z Bam runs have shifted well to the east; and so I expect the trend to continue with the globals. Looks like it may miss Cuba all together. So it's up to PR, DR, & Haitian mountains to keep her in check.

Why am I sure I am about to hear pumping the ridge? LMAO
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Levi, if you are out there... Do you think that is an eyewall forming?
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The best post of the PM...The weakness retreating indicates that the storm will track further west and once again you will see the models change as Irene will easily run a cycle now slightly north of west and not wnw. The steering flow tells the story...thanks for this post


Quoting USAFwxguy:
You can see in the CIMMS images below how the Atl high has gained some ground into the FL peninsula, as the CONUS high retreated just a bit

-3hr


Current:


The weakness over the Eastern GoM is facilitated by the retreating CONUS high, as opposed to the Atl high eroding. That should cause Irene to move generally westward in the near term.
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1654. RyanFSU
ECMWF 12z tighter zoom: Solid Category 3

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Quoting atmoaggie:
Honestly, *could* be. But will Irene maintain it?



Nope, it didn't because it's not an eye.

Member Since: July 15, 2006 Posts: 17 Comments: 10159
Quoting breald:




That storm is also why the hockey team Carolina Hurricanes got their name. They moved to Raleigh shortly after the storm hit. People were a little mad at the name they picked..LOL. A little useless tidbit.
I have many friends who is Hurricanes' fans. They LOVE the name now and they call themselves, "Caniacs".
Member Since: August 1, 2011 Posts: 28 Comments: 7902
WIND SWELL
6am ENE 33mph ESE 15.1 ft @ 11 sec
9am ENE 39mph ESE 18.4 ft @ 12 sec
12pm E 43mph ESE 24.3 ft @ 13 sec
3pm E 44mph ESE 27.2 ft @ 13 sec
6pm ESE 43mph ESE 27.9 ft @ 13 sec
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1650. MZT
Quoting connie1976:
The people here are so funny!! ...each day the models shift, so there are always a new group of people... watch tomorrow it sends it out to sea...so the fishcasters will be here...
Once it does form an eye, then comes the "wobblecasting" ... It jogged north! It dipped west! The models are all wrongzor!
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Quoting Dennis8:


Are you in Nassau?
LOL no I am in Naples Fl. But have a home in Abaco.
The airports will be flowing with outbounders trying to leave.
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Honestly, *could* be. But will Irene maintain it?

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Quoting Hurricane1956:
Don't understand why the National Hurricane Center has not! change the track cone to the East??,all Models are now in agreement that it will go East of us here in Miami,any thoughts?? about this.
I don't think they update the charts and what not until 5 pm. Right?
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1646. WxLogic
Quoting connie1976:
The people here are so funny!! ...each day the models shift, so there are always a new group of people... watch tomorrow it sends it out to sea...so the fishcasters will be here....lol...(although, if it does that I believe it will atleast hit the bahamas...so it really isn't a fish storm)...lol...


It never fails.
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I guess if it is, or even if it isn't, it doesn't really matter either way, lol.
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Repost

18z models

Little bit of Hispaniola

FULL IMAGE

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that was awesome to see an eye pop out right before your very eyes like that. kinda creepy. my prayers are with anyone in this storms path. it don't look to bad yet, but that eye did appear out of nowhere. wonder if it will stay that way or what?
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Quoting Neapolitan:
Keep this handy reference, Taz:

Pinehole or pinhole

;-)



LOL
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
All of the 18z Bam runs have shifted well to the east; and so I expect the trend to continue with the globals. Looks like it may miss Cuba all together. So it's up to PR, DR, & Haitian mountains to keep her in check.
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Quoting Stormchaser2007:


Cone is only updated at 11 and 5

Thank you
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People on here are ridiculous. There is no eye, the storm is moving due west, and there is a lot of uncertainty with regards to track and intensity. No need to overhype this thing right now. Let it play out...
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Quoting TropicalAnalystwx13:
You can see once the mid-level center and low-level center aligns, it develops that eye.

Really beautiful, thanks ...

There she blows ... with Puerto Rico in her sights?

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Quoting NICycloneChaser:


Ah, I see the surface pressure has risen, to 99999mb. Fairly high.


Nearly a 100bar. Even Jupiter doesn't create that much pressure on its surface.

The Great Red Spot would be jealous of such an estimate.
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1636. dearmas
Quoting weatherxtreme:
I am confused now with all the wishcasting..."it's going to NC,GA,SC etc... so will florida be out of the cone now at 5pm?


Thank you, was justing getting ready to ask the same....I'm lost ;)

Tampa Fl here
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Keep this handy reference, Taz:

Pinehole or pinhole

;-)
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Quoting spathy:


It looks like its not completely stacked vertically.(yet)
See the little spin to the SE of the eye like feature.


It is stacked, recon confirmed this.

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Quoting connie1976:
The people here are so funny!! ...each day the models shift, so there are always a new group of people... watch tomorrow it sends it out to sea...so the fishcasters will be here....lol...(although, if it does that I believe it will atleast hit the bahamas...so it really isn't a fish storm)...lol...


Yeah, the Fishcasters are on break today but will probably show up tomorrow when models change again LoL!
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WOW!!! I just got home from work and the models have shifted ALOT in the past 24 hours. My area (Wilmington NC) is now directly in the threat area... and if anything, maybe the north side (meaning we'd get the worst of the storm were it to make landfall slightly south of here in SC).

Any thoughts on why these models have moved, if they will slide back east (to florida), and IF it stays over open water coming my way... how strong can this thing get?

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Quoting NCHurricane2009:
http://www.ssd.noaa.gov/goes/flt/t2/flash-vis.htm l

This is not random...this is an eye! Look at the last three frames...high clouds circle the immediate center and form an eye wall...then an eye suddently pops in the middle at the end...

...that also means Irene has been going straight west for a while....a track going straight for the S coast of Puerto Rico or just S of Puerto Rico...and direct strike for Hispaniola...which means weaker storm due to mountainous terrain disruption and perhaps a more westerly track than an east coast threat...hmmm....



here that guys someone who lives in the carolinsa and isnt a wishacaster i agree with ya
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Sigh...I guess some are going to believe what they see, regardless if it's real or not.

I guess we have about 3 or 4 eyes in this new rapid scan frame:

Member Since: July 15, 2006 Posts: 17 Comments: 10159
Quoting HCW:
LOL
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ok...out till 5 or so...laundry to do...
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18z models

Little bit of Hispaniola

FULL IMAGE

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1626. Dennis8
Quoting Abacosurf:
I would be outa there by Tues. PM.

Honestly.


Are you in Nassau?
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1625. WxLogic
Quoting USAFwxguy:
You can see in the CIMMS images below how the Atl high has gained some ground into the FL peninsula, as the CONUS high retreated just a bit

-3hr


Current:


Which is why i don't see any movement of Irene to the N or NW until it gets past DR... unfortunately.
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Ok, so it's definitely an eye. Agreed that it doesn't have the ring of extreme deep convection around it, but it does have some around it. The dry air ingested on the western section has caused this but as the larger band to the north continues to wrap in our convection should pop in the next several hours near the eye.

Irene is vertically stacked in a very low shear environment, even a "weak" eye will show.

Another thing to confirm this is the recon data. There is a sigificant temperature increase inside the eye versus outside. It is this temperature increase from sinking air in the eye that clears out the eye in storms.

I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 15°C (59°F) at a pressure alt. of 1,530m (5,020ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 21°C (70°F) at a pressure alt. of 1,519m (4,984ft)
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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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