Category 2 Irene Approaches The Bahamas

By: Dr. Jeff Masters , 7:51 AM GMT on August 23, 2011

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As of 2am EDT, Hurricane Irene was located at 20.1N, 69.7W, 135 miles southeast of Grand Turk Island. It was moving west-northwest at 12 mph with maximum sustained winds of 100 mph, making it a Category 2 storm on the Saffir-Simpson scale. Irene has a minimum central pressure of 978 mb. Hurricane warnings have been issued for the northern coast of the Dominican Republic from the Haiti board to Cabo Engano, the southeastern and central Bahamas, and the Turks and Caicos islands. Hurricane watches have been posted for the north coast of Haiti from Le Mole, St. Nicholas to the Dominican border and the northwestern Bahamas. Tropical storm warnings are in effect for all of Haiti and the southern coast of the Dominican Republic from Cabo Engano to Santo Domingo.

5AM Update
As of 5am EDT, Hurricane Irene was located at 20.3N, 70.1W, 105 miles southeast of Grand Turk Island. It was moving west-northwest at 12 mph with maximum sustained winds of 100 mph, keeping it a Category 2 storm on the Saffir-Simpson scale. Irene has a minimum central pressure of 978 mb.

Figure 1 shows that Irene is maturing into a vigorous storm, with apparent waves in the western edge of the cirrus outflow.


Figure 1 IR satellite view of Irene taken at 135AM EDT, August 22, 2011

Track Forecast

Irene is forecast to move to the north-northwest, passing over all of the Bahama islands by Thursday evening, at which points it starts curving to the north. Irene is forecast to make landfall in the US near Wilmington, NC Saturday evening. However, it is important to note that this is not a definitive forecast, the average forecast error for day 5 is 250 miles. The timing of Irene's recurvature depends on how quickly several small troughs of low pressure in the Northeastern US move to the east. After Saturday, Irene may pose a threat to the mid-Atlantic coastline and locations further north, but it is too early to make a skillful forecast for those regions.

NHC is forecasting for Irene to become a major hurricane (winds faster than 110 mph), within 24 hours, then reaching peak intensity at 130 mph (Category 4 storm) by 8pm EDT Thursday evening.

Forecast models and adaptive observations
The different forecast models are in rough agreement until Irene nears the Carolinas. The dynamical hurricane forecasting models, GFDL and HWRF, have Irene making landfall near Charleston, SC. NGFDL (a variant of the GFDL that uses NOGAPS for background conditions) has landfall near Morehead City, NC, and the GFS has Irene crossing the Outer Banks. The UKMET forecast track splits the difference, placing Irene near Myrtle Beach, SC at landfall.

To reduce the model spread, and improve the track forecast error, the NOAA Gulfstream IV and an Air Force WC-130J have been flying dropsonde missions north of Irene. A dropsonde is an meteorological instrument package dropped from a plane that can tell you the vertical profile of temperature, pressure, moisture, and winds. By flying these missions, the dropsondes can improve all of the numerical weather prediction models initial picture of the atmospheres, which improves the forecast. Also, NHC has asked NWS offices in the southeastern US that launch weather balloons to do so every 6 hours instead of the normal 12 hour frequency.


Figure 2 Official track forecast of Irene as of 2am.

5AM update
The 00Z ECMWF forecast is available and Figure 3 shows the maximum wind speed over the next week for the eastern coast of the US. Green indicates tropical storm force winds, while yellow and orange are hurricane-force winds. The important thing is not to fixate on the predicted landfall location, but to see that Irene's winds will affect areas far away from landfall. The GFS, not shown, agrees with ECMWF that Irene will have a large area of tropical-storm force winds associated with it.

Figure 3 Maximum wind-speed in mph from the 00Z August 23 ECMWF forecast for the next week.

Impacts

In the immediate future, Irene is expected to have a significant impact on the Bahamas and surrounding islands. Hurricane force winds are forecast to reach the southeastern Bahamas and the Turks and Caicos sometime this afternoon or evening. These locations can also expect 5-10 inches of rain. Three to six inches of rain are forecast over northern Hispaniola, with isolated areas receiving up to 10 inches. This could lead to flash flooding and mudslides in mountaineous terrain. NHC is predicting a storm surge of 9-13 feet above normal tide level for the southeastern Bahamas and the Turks and Caicos.

Outside of the islands immediately impacted by Irene, it is my judgement that everybody living on the eastern coast of the US should monitor Irene and review their hurricane preparations over the next few days.

Dr. Masters will have a new blog entry this morning, and Angela Fritz will be covering the afternoon. I'll be back on third shift tonight.

Thanks for reading,

Dr. Rob Carver

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http://www.ssd.noaa.gov/goes/east/carb/
flash-wv.html

Being in east central florida, I wont let my guard down until I see definite NW turn of storm and it passes my latitude. With that in mind, paranoia requires me to ask you to look at a feature to the NE of Irene. Can that make a change to what I hope is a recurve of Irene out to sea? BTW, the trough digging down pleases me because it looks like it will force Irene to miss everyone from a direct hit.

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This is every MODEL known to man......LOOKING BETTER for a non ConUs direct hit!
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kb8cane. Best thing you can do this morning is calm down --I DO understand. You can see from my name where I am and hard not to be in dither. Clear heads needed to make good choices. IF any doubts---take your son and go to one of the shelters.

In the meantime try and prepare you home as best you can. The worst part is the wait. I am hoping she moves more east and the center stays over water and we get the easier side:-)
To be honest, at this point---TS conditons would be considered a gift!!

County EM should start a ramp up soon----pay close attention to them---what they have to advise and are going to be doing. Blog here is great for general info--have to pay attention for US right here-----

I am a vet of these storms and while it doesn't make it much easier---I will be glad to help you in anyway I can-----BAD to be alone with a young man to take care of----


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those models DEFINITELY looking better
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These are the BAM MODELS.........WOW they have been RIGHT on with IRENE........unreal how well they have performed based on intensity...gotta say the GFS has been all over it also.
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Quoting Grandpato4:
The models trending off the NC coast have me hopeful that Irene could go out to sea still.
It already made landfall in the US as a Hurricane Pueto Rico is the United States, so its impossible to miss the united states because it already hit it.
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Quoting Grandpato4:
The models trending off the NC coast have me hopeful that Irene could go out to sea still.


Irene is still very likely to bring some significant impacts to the coast even if it stays offshore.
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Quoting NICycloneChaser:
*Sigh*

Looks like we aren't going to get anything at all from that HH plane. Has to be said, there's been several occasions this year when recon planes have had problems.


Looks like they went home.

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Honestly, if there had been better-formed storms this year you'd all be pointing out what a mess of a storm she is. And, how she's hung up on the mountains. But maybe I don't see the "bigger environment" reason that she's going to push off that island and go.
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Quoting Grandpato4:
The blog is moving more at my speed this morning. Last night I would read a page and then hit refresh and the blog would have gone 2 or 3 more pages.


Hey Grandpa, I'm not totally sure that Raleigh is a safe bet. I'm in Wilmington and may go to Charlotte.

What do you guys think the effect of the gulfstream will have? My very newbie weather watcher mind says major strengthening.
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NEXT UP........:(
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Quoting ProgressivePulse:
Definitely trending to a complete miss with the exception of the Bahamas. Following the right path could put the Bahamas on the left side as well which would be as good of news as you could get out of the situation. Stay Tuned...



Those models on the right aren't exactly great (BAMS, AEMN, etc.)

The consensus still very much favors direct impacts unfortunately.
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Quoting WeafhermanNimmy:
I am going to say this and say this again! This will not impact the US.

Any evidence that proves it would be nice.
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Member Since: December 18, 2006 Posts: 7 Comments: 2685
*Sigh*

Looks like we aren't going to get anything at all from that HH plane. Has to be said, there's been several occasions this year when recon planes have had problems.
Member Since: August 10, 2010 Posts: 2 Comments: 1970
If the 12z models hold to the same general area (which from the look of the 12z BAM models, I think they will) then pretty sure we will be able to breath a little easier here in Chucktown. Wilmington and East will still need to keep a close watch on her though.
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I am going to say this and say this again! This will not impact the US.
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Considering the current forward speed as it nearly stalled, the turn more to the NW is now probably coming.
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Quoting K8eCane:



I wish we could be sure of that. But until I hear it from the NHC....


This forum is a very bad place to get information to make decisions on preparation or evacuations (you are correct in waiting to hear from HPC)

With that said, this is a forum to talk weather (and spray so it seems) The current model situation is like almost all others in that the models can do whatever they want (they are bound by the laws of physics) but the current observations are, and that’s what counts. They are pointing to a different picture of a track. There is no way Irene is going to make landfall if the next 2 upper level disturbances are as strong of the one from this weekend over the northern US. (and short term historic observations point to a decent probability of that happening)
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Quoting connie1976:


This is really good news!!!



Indeed, Irene has been trending right since she began. Hopefully the trend continues, nobody needs a CAT4. Trends can change however, this is just the flavor of the morning :-)
Member Since: August 19, 2005 Posts: 5 Comments: 4863
559. Jax82
Quoting ProgressivePulse:
Definitely trending to a complete miss with the exception of the Bahamas. Following the right path could put the Bahamas on the left side as well which would be as good of news as you could get out of the situation. Stay Tuned...



Good news.
Member Since: September 2, 2008 Posts: 1 Comments: 1261
Quoting WeafhermanNimmy:
Is hoping for shift west so we can feel the rain and wind in Greensboro, NC!


Those of us in ENC disagree..
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For anyone thinking about whether to evacuate or not, please look at this from 2008, and remember hurricane Ike was a Category 2. Prayers and thoughts are with EVERYone who was/is/will be affected by Irene.

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I posted yesterday that if we get lucky Irene will become a monster and by doing so just might miss the ConUs......that just might happen....but, the Bahamas will suffer severe issues in doing so...someone gain anothers loss......:(
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This is a image of a rare tornado that TS Harvey spawned in Belize
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Is hoping for shift west so we can feel the rain and wind in Greensboro, NC!
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I think it is a bit too far east in projected track.

We will see.
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Quoting ProgressivePulse:
Definitely trending to a complete miss with the exception of the Bahamas. Following the right path could put the Bahamas on the left side as well which would be as good of news as you could get out of the situation. Stay Tuned...



This is really good news!!!
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Where's WeatherNerd? i think there's a blackout in their area...
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The models on TWC are different then the ones on this site. They are all basically clustered to go to the coast of NC or offshore.
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Quoting presslord:


That is the most enlightening post we'll see all day!!!


indeed.

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Quoting Jax82:
We could possibly see a major hurricane hitting the northeast, if she does scoot through eastern NC she's going straight up with coast with hurricane force winds. Im praying she gets pulled out to sea.
Could be like Bob, only larger, Bob was only about wide as Massachusetts.
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IN MODELS I TRUST........They have done an excellent job thus far as a big picture. We tend to all look at the long term outlook when really anything beyond 3 days just can't be trusted. I see the models shifted to the East overnite after moving West slightly yesterday.
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Well Turks and Caicos up first. Are there any radars in this area? I've looked everywhere.
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Quoting hurricane23:


The threat for tropical storm winds across mainland south florida has continued to decrease. Gusty winds in the range of 25-35mph and some rain is expected as the storm makes its closest approach . The strongest winds will be over offshore waters.


To add most impacts will be coastal in nature as far as the East Coast Florida is concerned. Some minor beach erosion is possible along with some nasty rip currents. So basically unless you are coming to surf, assuming you know the risks, I would avoid the beaches.
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Quoting Smikey:
I don’t normally jump into the foray of post slinging during wunderhype time, (with no disrespect to those that actually bring meaningful facts to the discussion) but something that has not been discussed:

The GFS, and Euro and other models continue as of this morning to under forecast the strength of the Upper level disturbances over the Northeast US. Its fall in the Northeast this morning (55 degrees where I’m near the NJ coast)


I agree with met Steven DiMartino with his post this morning stating:


“However, the models have been under forecasting the strength of these disturbances as early as this morning’s observations, and that factor can not be discounted when examining the model guidance. A strong disturbance means that influential steering currents from the southwest must be taken into account in the error and thus a faster turning of Irene back into the Atlantic is still very much on the tables. In fact, there are now several models pointing to Irene staying off the East coast completely.”

,i put the chance of landfall along the east coast at 33% now and falling,by tomorrow nc should be on the west side of the cone,jmueo
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Definitely trending to a complete miss with the exception of the Bahamas. Following the right path could put the Bahamas on the left side as well which would be as good of news as you could get out of the situation. Stay Tuned...

Member Since: August 19, 2005 Posts: 5 Comments: 4863
541. Jax82
We could possibly see a major hurricane hitting the northeast, if she does scoot through eastern NC she's going straight up with coast with hurricane force winds. Im praying she gets pulled out to sea.
Member Since: September 2, 2008 Posts: 1 Comments: 1261
Quoting floodzonenc:
Welcome.  When I say your name, I sound like an old man with a speech impediment... j/k.



Lol. Thanks.
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Irene is now moving far enough away from Hispaniola such that the island is having less of an effect on the system.

The topographic-enhanced convection to the south of the island is beginning to weaken and the inner-core of the storm is becoming more symmetric.

I think we should start to see a new round of intensification in the very near-term that should bring Irene up to cat 3 and 4 rather quickly. Get ready cause Irene's set to bring it to the next level.
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Quoting ElConando:
I like the early morning blog, calm and fairly civil and not going 3,000 mph.

I fully agree. Its nice to actually be able to read posts. We should have a few more hours of sanity, then the insanity will begin. (I'm willing to bet that today, someone asks the blog what the development chances of something in Africa is, since SFL is out of the cone for the most part now, and Irene no longer exists to that person)
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tornado Warning for Eastern Puerto Rico
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Thankfully, Tampa Bay and almost all Florida are out of the woods this morning. I hope Irene make that turn well before and recurve before touching any US land area. My thoughts and my pray are with those in Hispaniola and Bahamas.
Member Since: August 23, 2006 Posts: 0 Comments: 1563

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.