Hurricane Irene Approaches the Bahamas

By: Dr. Jeff Masters , 7:42 AM GMT on August 24, 2011

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As of 2AM EDT, Hurricane Irene was located at 21.3N, 72.6W, 400 miles southeast of Nassau. It was moving west-northwest at 9 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 966 mb. Hurricane warnings have been issued for all of the Bahamas and the Turks and Caicos Islands. Tropical storm warnings are in effect for Haiti from Le Mole St. Nicholas to the Dominican Republic border.

Satellite Views
Figure 1 shows that Irene has a large eye visible in infrared imagery, (26 miles across accoring to a report from the Hurricane Hunters at 130AM) with well-defined outflow cirrus bands. Tuesday evening, TRMM, NASA's tropical research satellite, flew directly overhead Irene, getting a radar scan of the storm using it's downward pointing radar, shown in Figure 2. It is immediately apparent that Irene has well-developed bands of rain showers, with strong storms present in the eyewall.


Figure 1 IR satellite view of Irene taken at 113AM EDT, August 23, 2011


Figure 2 TRMM radar overpass of Irene at 713PM EDT, August 22, 2011. Image courtesy of the Naval Research Laboratory

Track Forecast

Irene is forecast to move to the northwest, passing over all of the Bahamas by Thursday evening, then curving to the north. Irene then makes landfall in the US near or at the Outer Banks Saturday afternoon, then traveling along the mid-Atlantic coastline of the US. After Saturday, Irene may pose a threat to Long Island and the New England coastline. However, NHC is quick to remind us that the average forecast error for day 4 is 200 miles, so don't stop your hurricane preparations if you aren't in the immediate area of landfall. It is also important to note that the windfield of Irene is expected to be large, affecting areas distant from the immediate track of Irene's center. Tropical storm forces winds are expected to be found out to at least 150 miles away from Irene's center on Friday afternoon.

NHC is forecasting for Irene to become a major hurricane (winds faster than 110 mph), within 24 hours.


Figure 3 Official track forecast of Irene at 2AM EDT.

Forecast models and adaptive observations
The different forecast models are in fairly good agreement about Irene's track through the Bahamas and along the east coast of the US. The GFDL, a dynamical hurricane forecasting model, which had been a western outlier from the other models is now agreeing with them. When a set of weather models using slighly different initial views of the atmosphere and slightly different ways of simulating how the atmosphere works all agree on a forecast, then meteorlogists tend to believe that the forecast is more likely to occur. The 00Z GFS and ECMWF (wind swath shown in Figure 4) forecasts are nearly identical, which furthur boosts forecaster confidence.

In the 11PM forecast discussion, the NHC forecaster praises the NOAA Gulfstream IV (aka Gonzo) for providing infomation about the atmosphere around Irene that will influence it's track. Looking at the plan of the day valid for today, it will be a busy day for airborne reconnaissance. Three flights for the Air Force hurricane hunters, two flights for the Gulfstream IV, and two flights for NOAA 42, a WP-3D (aka Kermit).


Figure 4 Plot of the maximum sustained winds in mph over the next week from the 00Z ECMWF forecast.

Impacts

In the immediate future, Irene will have a significant impact on the Bahamas and surrounding islands. Hurricane force winds are ongoing over the Turks and Caicos islands and southeastern Bahamas. These locations can expect storm surges that are 5-8 feet above tide levels. The northwestern Bahamas can expect hurricane force winds Thursday, and storm surges that are 7-11 feet above tide levels. The Turks and Caicos islands and all of the Bahamas can expect 6-12 inches of rain over the next two days.

I still think people living along the east coast of the US should closely monitor Irene and review their hurricane preparations. Irene will be a large storm, impacting areas far from the storm center track.

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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1328. Mucinex
Quoting E46Pilot:



People still use IE, thats the problem. Use Mozilla Firefox, it is much better, and no problems.

The problem is that some of us are at work or accessing the site from locations were there is no choice but to use IE. The Admins have known this for years but have done nothing to fix it.

However, for those on IE, if you wait for the page to turn over, the blog will return to it's normal appearance.
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Irene has been heading due west for the past 3 satellite frames (90 minutes). I think she's finally feeling the ridge and knows she has to go around it before going north, and that is why I have been saying expect Irene to be quite a ways west by the time it gets near FL, than what the models have been predicting.
Member Since: September 2, 2008 Posts: 0 Comments: 744
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Quoting Floodman:


I have always used IE and had relatively few problems


I use Chrome and Firefox but Firefox is a memory leaking piece of crap. I find Chrome to be the most stable with no memory leaks and it's HTML 5 compliant...

Irene does look like she's wobbling west of forecast points but I'm sure the course correction wobble is coming anytime...
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Quoting RitaEvac:


If she is at 77W, even if she starts going North it's already to late in my book


Yep alot riding on when that next short wave gets to the NE, if it's delayed or weaker than forecast this thing is not going to turn like they are forecasting it to turn! She's already crossing 74W and still heading in that WNW direction.....
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Out to 24, the GFS is slightly farther SW than 6z.
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After 24 hours the 12 GFS is south and west of the 6z...

12z:


6z:
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It has changed from 290 to 305 degrees on the 11:00AM update from the NHC. I will be alot happier when it gets past Jupiter Fl. but due have faith in the NHC track.
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1318. hcubed
Quoting clodburst2011:



yes joe b scares me sometimes with the crazy predictions he comes up with...i guess we can say joe b hit a homerun on this one..just hope its not to devastating...


Heck, some of the posters on HERE scare me with their crazy predictions.

One guy a few years ago kept bringing every storm into NOLA as a cat 5...
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Eve
Quoting Neapolitan:

Precisely. To show this, I've combined the NHC's 3- and 5-day cone from Sunday afternoon with the storm's track as of last evening. It's true that Irene has stayed against the hard right side of that cone--but she's stayed within that cone nonetheless. Bottom line: the NHC's 3-day cone is pretty much rock solid. Folks who ignore it do so at their own peril...

Irene


Good point, people from Wilmington NC, to Boston MA needs to understand its ALL ABOUT PREPARING FOR THE WORST and hoping for the best.
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I live on the FL east coast just above Melbourne. Even if it is on NHC track, I'm not taking my eye off this one until it makes that more northerly turn. She's at 74WW Now and still moving slightly more west than north. I don't fully trust the model at this time.

Best wishes to and praying for all you folks in the Bahamas.
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Quoting RitaEvac:


Yea....better make a hellava turn now if that's the case




yah, NHS i bet is hoping for a hard turn. but what's there 2 do it? nothing....and now she enters the shallow waters around Bermuda (hottest water in the Gulf Stream) with a bullseye on Miami.....
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Quoting CaneHunter031472:
Ridge is buliding back to the west. I'm not seeing any changes in the models, but I'm sure they will follow soon. Anyone has any comment about this? I'm not going to make wild guesses at this point.


If this holds all bets are off, I would expect a shift west in the projected path jmo.
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12Z NOGAPS and GFS both have Irene getting pretty close to FL coast...

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1311. GoWVU
Quoting ILwthrfan:
Steering layer for 950 mb to 969 mb system





still looks like a SE coast threat???? she needs to start turning now!!!
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Quoting 69Viking:


That's still more West than North dah which indicates a WNW movement just as I said earlier!
She needs a bigger north movement than a west movement to be going nw.
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Like I said if there is a Westward shift it would not likely be much, but my concern is growing for Nassau in the Bahamas, I hope they're prepared...
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1308. Vero1
Quoting ecupirate:
The eye has been nailing the NHC tropical points dead on for the last 12 hours.

And every 6 hrs NHC moves the points to the eye.
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Quoting jonelu:
NHC has been dead on with Irene especially through day 3. So Fl is fine and unlikely to get anything more than gusty winds and rain.


How can you say they were dead on...they completely missed the forecast when she went north of hispanola. They had it going over Hispanola and some earlier forecasts we're for it to go south...JMO
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Quoting 69Viking:


That's still more West than North dah which indicates a WNW movement just as I said earlier!


Very true, good point. I'd say we are going to see a more gradual than sharp turn with her.
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Quoting JasonCoolMan2004:
sorry for porn pic!!!
Jason you commited a offence not only to this blog but to the whole world posting porn on a open blogg like this i hope Weather Under Ground Reports you and you get charged for the offence . They could be sued for what you did on there blog
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and to add to that, the upper level pattern change is supposed to begin by Friday with the Bermuda High shifting westward into the western atlantic parking itself.

September will be interesting. That High looks to be in place. Not to sound crazy but if a storm is in the wrong place at the wrong time, Florida will be a sitting duck as well as the other gulf coast states

some of the GFS models indicate the High getting stronger as well
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Quoting cornchucker:
Posters are really begging for a U.S. landfall, and those who are, are no better than the vultures at the weather channel begging for something news worthy. After a week of reading posts, the media, and this forum continues to pretend that Irene has already made landfall with posts like "Irene a historic storm to slam into North Carolina", etc, etc. Well guess what folks, you can talk and talk about Irene not taking the turn toward the north and east, just like previous storms, but one way or another, this storm will continue to head out to sea. Get over it and salivate over the next tropical wave.


Yea....better make a hellava turn now if that's the case
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Anyone have any idea where this thing is going, just based on the main feeder band on the west side--- I have heard there is a way to tell, but I am not sure if that is true or not. Anyone?
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Quoting Hurricane1956:
With all your respect,I believe the eye of the Hurricane is following the Hurricane Center points exactly as they lay it out.I'm very confident here in Miami about the Hurricane Center confidence in their track otherwise they could easily issued Warnings this morning or yesterday,this is my own opinion after being a member of this blog for many years,the Hurricane center track in the 2-3 days range is 90% accurate.

Precisely. To show this, I've combined the NHC's 3- and 5-day cone from Sunday afternoon with the storm's track as of last evening. It's true that Irene has stayed against the hard right side of that cone--but she's stayed within that cone nonetheless. Bottom line: the NHC's 3-day cone is pretty much rock solid. Folks who ignore it do so at their own peril...

Irene
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the shortwave trough lost. in my eyes this is academic at this point, but here is my daily prediction...


by 10:00 est in miami crap will be hitting the fan in the lil brick stormhouse.....panic sets in as they realize......
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Edit

Already posted
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Steering layer for 950 mb to 969 mb system



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The desperation of the Florida wishcaster is ramping up. The further North it goes the louder they scream, "It's heading west, see that wobble"?
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Quoting jonelu:
NHC has been dead on with Irene especially through day 3. So Fl is fine and unlikely to get anything more than gusty winds and rain.



ok , if you say so. enjoy the anomaly reading as the eye approaches 80w down low.....lol
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1295. wpb
noaa plane heading back will croos ovr broward county in 30 min
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1294. Mucinex
Quoting IMA:
For the vets on the block

LoL! Of course! The Bronies will defend NY!
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Quoting cornchucker:
Posters are really begging for a U.S. landfall, and those who are, are no better than the vultures at the weather channel begging for something news worthy. After a week of reading posts, the media, and this forum continues to pretend that Irene has already made landfall with posts like "Irene a historic storm to slam into North Carolina", etc, etc. Well guess what folks, you can talk and talk about Irene not taking the turn toward the north and east, just like previous storms, but one way or another, this storm will continue to head out to sea. Get over it and salivate over the next tropical wave.


Well now that we have your permission....
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She's top heavy, gonna be harder to turn, big storms like this tend to control environment around themselves therefore more westward if you will
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Quoting ILwthrfan:


Well I got her going 1.1 North and 1.3 West over the last 8 hours, that was from 2 AM position to 10 AM position. So she has made that NW turn, it's just a question is when she decides to make those "other" turns.


That's still more West than North dah which indicates a WNW movement just as I said earlier!
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12hr:
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Quoting ILwthrfan:
You talk about steering layers. Look at this one, if she were to continue to strengthen it would put her in the 949 mb and below this would be her steering layer.

img src="http://tropic.ssec.wisc.edu/real-time/atlanti c/winds/wg8dlm6.GIF" style="m
ax-width: 501px; width: 500px; ">


It's really tight. I can't say the High will stay like that, strengthen, or weaken over time. We'll just having to wait and see, it's holding steady for now tho..
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1288. jonelu
Quoting odinslightning:
as I predicted yesterday the storm hasn't made a hard hook to the right and I dont believe it will. The eyewall is now at 74w/22.4n . The NHS had this plotted at 74/24 with this already making its hard hook. They were wrong....

The weak shortwave trough lost the war against the bermuda high. Get ready florida, thats all I can say.
NHC has been dead on with Irene especially through day 3. So Fl is fine and unlikely to get anything more than gusty winds and rain.
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Quoting cloudburst2011:



rita the gap is closing in on IRENE...SHE BETTER START MAKING THE TURN SOON OR SHE WONT MAKE IT AT ALL...SOUTH FLA MAY HAVE TO BE UNDER TROPICAL STORM WARNINGS IF THIS WEST JOG CONTINUES FOR 12 HOURS...VERY INTERESTING THIS TROF MAY NOT BE AS STRONG AS THEY ARE PREDICTING..ITS POSSIBLE IRENE WILL NOT GET PICKED UP BY THE TROF THEN WE HAVE A REALLY STICKY SITUATION HERE..


so what does this do to your prediction 70% fish?
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Quoting Floodman:


I have always used IE and had relatively few problems
I use Chrome. :D

Try it...much much better than IE.
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1284. rv1pop
Quoting yonzabam:


Mine doesn't work for Jason. Tried it four times in the past twenty minutes. He's getting smarter.
reminds me of Littleton
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1283. 7544
could she come closer to so fla if the high is that strong and the high is moving west if so by how many miles closer sorry dont know how to red the lines on that sterring map tia
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Quoting odinslightning:
Get florida, thats all I can say.


I guess it time for you to create your own Hurricane Center. You know more than the professionals.
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Quoting CothranRoss:
Does anyone else have a slight vibe that the model consensus it a little bit too east? I kind of do, and it seems like everyone on the blog does.



ummm lol yah.


bermuda high = best SEC offensive line.


running back to the left out of the backfield around the flank..... NHS may give up a touchdown down the sidelines on this one....
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Quoting E46Pilot:



People still use IE, thats the problem. Use Mozilla Firefox, it is much better, and no problems.


I have always used IE and had relatively few problems
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1278. HCW
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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