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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Uh oh...time to break out your *poof* list again, everyone...*sigh*
Member Since: Posts: Comments:
Quoting CarolinaHurricanes87:
I'll stop "bashing the nhc". But next time I wont take them seriously until 3 days out and I expect a lot of others to do the same. You just cant "cry wolf" about a MAJOR hurricane, something that can completely wipe a beach town out, then have zero effects on that beach town... without making people a little more skeptical next time around.

Off to work, glad my area will be spared but even more glad I didnt waste $$$ buying supplies like I was considering doing

Better to be on the SAFE side than the alternative...
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I think the NHC do a great job. We need to remember that Wx prediction is not an exact science. It's fluid with lots of variables. We have computer models that help speed up the analysis, but we need the PhD's to make the final word. I thank them for their service.

Interesting to note that so far in this satellite/radar loop that Irene is tracking slightly to the right of the cone center line.

14 hr loop
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875. hamla
who would you rather have giving info on the tropics the nhc,tpc or fox case solved
Member Since: August 29, 2008 Posts: 0 Comments: 167
Going back in the imperfect historic record of coastal storms, there are believed to have been at least five epic hurricanes — in 1938, 1893, 1821, 1815 and 1635. One theory is that they repeat every 70 to 80 years. It likely won’t be this storm. It might not be this year. But it will almost certainly happen again, no matter how many masters of the universe build seaside monuments on terrain where nothing will last forever.
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That is not good
Quoting CaneHunter031472:
12z Early Cycle NHC model tracks
Irene

Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)


Dynamic Models (More sophisticated models)

Member Since: Posts: Comments:
Quoting 69Viking:


I think all cones should have the line removed out past 3 days, this way everyone in the cone area knows to be aleart and prepared but not to worried just yet that they have to evacuate. At 3 days out it's more critical to make possible evacation plans so the line should be there.
I think you are right.
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Quoting gulfscout:
Still much of the carolina coast will still be in the cone today and should monitor and prepare with a storm this size.


well....no...not exactly...much of the South Carolina will not, in fact, be in the cone
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Folks, whats going on here, I here this story and that story, except for the Bahamas, is Irene going to be a fish storm?

Is the Trough going to push her out to sea?
Why is everyone so tough on the NHC?

Look at Cantore and the Weather Channel, talkin about scarring people!
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Quoting WeatherNerdPR:
Puerto Rico got blasted by Irene's butt.
And I STILL don't have power.


baby got BACK
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Member Since: July 3, 2005 Posts: 426 Comments: 129093
Quoting CaneHunter031472:
12z Early Cycle NHC model tracks
Irene

Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)


Dynamic Models (More sophisticated models)


The Xtrap has Irene going through Miami and then into New Orleans. Just as well no one pays any attention to it.
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Damage estimates should come in tomorrow. I saw an article on the newspaper that said damages to agriculture were near $17 million.
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862. MahFL
After the wobble west she does jog NW, so all in all it's on track, but it's fun to watch !
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Quoting presslord:
In my never to be opinion...two things would resolve most of the NHC issues being discussed here:

1.) Stop with the 5 day forecasts....3 is plenty...and accuracy drops dramatically after that

and

2.) remove the center line....it is often misleading


Using that logic however in 2000 the 3 day cone was just as inaccurate as the current 5 day cone. So we should have had then a 24 or 48 hour cone. In my opinion the 5 day should stay, as they are working on a 7 day cone currently, doing in house this year a 7 day forecast, which I don't think is necessary. NHC claims that the professionals in Emergency Management are asking for the 7 day.


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Quoting Cat5Hurricane250:
954.5 mb
(~ 28.19 inHg)


It wouldn't surprise me if this storm bottomed out in the 930's.
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Quoting help4u:
joe b said this when everyone had it hitting Florida and going in gulf. His forcast was over two weeks ago

Joe Bastardi, Twitter 21 Aug,

... Irene has developed, and I have no changes... its a Florida/Se threat where the preseason impact forecast was centered


Did JB say that Irene will not hit Florida?

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Quoting Neapolitan:

Well, since tropical cyclones are inanimate objects with no mind and no self-determination, of course "something something is affecting the path and intensity of tropical storms and hurricanes in the Atlantic Ocean": SSTs, proximity to land, latitude, steering currents, synoptic weather patterns, the timing of EWRCs, and so on...


Right.

It's not like weird tracks for tropical cyclones are a new phenomenon.

People love a good conspiracy theory.
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Quoting Detrina:
Just popping in on a break at work. what is the latest on Miss Irene plz?
thanks:)
She's a Cat 3 with 115 mph and 957 mb.
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Quoting presslord:
Is there anything else out there we oughta be lookin' at?


Invest 90L off Africa and slightly south of the Cape Verde. In additon, there was one HELL of a storm happening in central Africa yesterday
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Is that the Bermuda High that I see pushing on the North Eastern periphery of Irene?
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Quoting Grandpato4:
I do not understand why my posts are being flagged when they are stating fact. I am just about done with this website. I see much worse stated on here day after day that gets praise and I state an island is accessible only by ferry and the post is removed.


Grandpa... This site is only for spreading false rumors and second guessing experts who have spent their lives studying storms and weather. Cheer up and just lurk, I find this blog as funny as Comedy Central
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852. MahFL
Irene now has the classic S shape.
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Quoting LurkerLizSC:
I believe that all the latest technology and sales pitches about accuracy have the public convinced that the cone is a pretty sure thing. When we see a cone, we expect it to be based on fact. I think that the cone should not be so specific until a few days out. Therefore, the NHC should focus more on tracking and less on long-term forecasting. My confidence in forecasting is fading fast this week. Speculation is damaging.


I think all cones should have the line removed out past 3 days, this way everyone in the cone area knows to be aleart and prepared but not to worried just yet that they have to evacuate. At 3 days out it's more critical to make possible evacation plans so the line should be there.
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Quoting NEwatcher:


I am sure that in 1938 they would have loved a 5 day warning. The NHC is there to inform so you can make the best preparations for your family.


I totally agree. In the end, the decision to go/no go is mine alone. The more information I have, the better the decision. I don't post often here as there are far too many idiots that would learn a lot more if they kept their hands in their laps and their eyes on the screen. From time to time, though, I'll toss my oar in the water... like this one :)
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Member Since: Posts: Comments:
Quoting Grandpato4:
I do not understand why my posts are being flagged when they are stating fact. I am just about done with this website. I see much worse stated on here day after day that gets praise and I state an island is accessible only by ferry and the post is removed.


We all know the quality of this site is going down, ppl need to stop the elementary school antics. There is a major hurricane forecast to strike the United States, and here we have ppl flagging innocent posts and having side conversations about idiot bloggers like JFV. This is my last post non-weather related...I hope this becomes a pay only blog, cause this is getting stupid.
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I've been following this storm every day since it was an Invest and nearly every time, the cone changed. I understand that they state it's not accurate past a certain time, but then some people, including me, need to stop paying attention to that cone because it clearly doesn't mean anything. When the models pointed at SC, I was reading all across the board about how bad it's going to be there. Whey they shifted east, it was disaster in NYC. Now, it's supposedly going to be terrible in OBX or LI or whatever else is in the cone but how can we really say this. For all we know, maybe this will hit Florida now. I mean, do we really know??
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Still much of the carolina coast will still be in the cone today and should monitor and prepare with a storm this size.
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Intrigued by the events of today! I was up all night following Irene, looking at various imagery, etc. But, I disappear off to work for a while, and BAM! We have a major hurricane. We are now 9-1-1. And folks this will be an emergency.
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the NHC's reach exceeds their grasp
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Quoting presslord:


the whole point of WobbleCon is...we don't know ;-)


Doh! thanks:) back to work, will check back next time I get a chance
Member Since: Posts: Comments:
Puerto Rico got blasted by Irene's butt.
And I STILL don't have power.
Member Since: Posts: Comments:
I'll stop "bashing the nhc". But next time I wont take them seriously until 3 days out and I expect a lot of others to do the same. You just cant "cry wolf" about a MAJOR hurricane, something that can completely wipe a beach town out, then have zero effects on that beach town... without making people a little more skeptical next time around.

Off to work, glad my area will be spared but even more glad I didnt waste $$$ buying supplies like I was considering doing
Member Since: August 4, 2011 Posts: 0 Comments: 631
Quoting CarolinaHurricanes87:


Hoping for disaster? Im just saying when they CALL FOR DISASTER... for everyone from texas to the OBX, and 99% of the people in these areas receive NOTHING, it hurts long-term how serious people take the situations. Im glad I hadnt started preparing bc Id feel like a fool had I spent time and $ in an awful economy and end up with a cloudy day and big waves...

They sounded an alarm for a lot of people when there was absolutely no reason to do so. If they arent sure in a projected path, maybe they should consider widening the cone or delaying the release of the projections until they are a little more sure.


When did the NHC ever provide a forecast that went west of central Florida (ignoring cone width)?
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting Gorty:


Put nicely... but you left out the two hurricane models that are west the GFDL and HWRF.


those models have been consistently west (and therefore the most consistently innacurate) for the life of the storm.
Member Since: August 14, 2008 Posts: 0 Comments: 546
Quoting Methurricanes:
If this goes just west of Narragansett bay as a Cat 3 this could have a record breaking surge, due to the funnel shape of the bay. However the Fox Point Hurricane Barrier will hopefully stop such a surge.


The great unknown with the virtually untested Fox Point hurricane barrier (built after Carole and no real storm surges of note since), is if it works to keep Providence safe, what's going to happen to the rest of the communities along the bay. The water has to go somewhere...
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Quoting floodaintcovered:
"Richard C. Hoagland ...technical science adviser to Walter Cronkite during the Apollo missions, worked with Carl Sagan developing the message discs placed aboard Pioneer spacecraft and has had a close working relationship with NASA%u2019s Jet Propulsion Laboratory for many years. Hoagland%u2019s own independent research group is called The Enterprise Mission.

"Hoagland claims, among other things, that after scouring hundreds of hours of satellite radar images from a variety of sources, he has documented a phenomenon which he believes is evidence that someone or something is affecting the path and intensity of tropical storms and hurricanes in the Atlantic Ocean. As sci-fi as that sounds, the evidence is quite compelling. %u2013 via Glenn Kreisberg at http://www.grahamhancock.com/forum/KreisbergG2.php

Well, since tropical cyclones are inanimate objects with no mind and no self-determination abilities, of course "something is affecting the path and intensity of tropical storms and hurricanes in the Atlantic Ocean": SSTs, proximity to land, latitude, steering currents, synoptic weather patterns, the the location and size of the A-B high, MJO, the timing of EWRCs, and so on...
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Quoting Detrina:


Lol which way are we wobbling Sir?


the whole point of WobbleCon is...we don't know ;-)
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12z Early Cycle NHC model tracks
Irene

Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)


Dynamic Models (More sophisticated models)
Member Since: August 1, 2007 Posts: 0 Comments: 201
On the anniversary of Hurricane Andrew...

Hurricane Andrew - Path Of Terror
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Quoting PrivateIdaho:
I copied my genetic code on my arm so I can be identified.



LOL!!!!!!!
Member Since: August 19, 2006 Posts: 13 Comments: 16042
Quoting floodaintcovered:


Not familiar with it
Richard is on as a guest alot,I have heard him speak before. That's all.
Member Since: June 24, 2007 Posts: 0 Comments: 1479

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About

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