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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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: 1498
Quoting presslord:


we're at WobbleCon level 4


Lol which way are we wobbling Sir?
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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


I agree completely. Would love to see a healthy discussion on this at some point.
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STATEWIDE, NC (WECT) – Governor Bev Perdue issued a statement Tuesday urging all North Carolina residents to prepare for Hurricane Irene.

The governor said the state's veteran emergency management team is ready for the forecasted hurricane, but citizens need to be prepared as well.

"Please make sure you have three days worth of food, water and supplies," said Perdue in a statement. "You may lose water or electrical power during the storm, and grocery stores and other businesses may be closed. Also make sure you know the evacuation routes in case you must leave the area."

Perdue explained that it only takes a short time to put your hurricane survival kit together, so do that now.

Click here to see a hurricane survival checklist to help prepare your kit.

"We will be ready if Hurricane Irene reaches North Carolina," Gov. Perdue said. "Our teams are already lining up supplies, trucks and resources to reach anywhere the storm might touch."

Gov. Perdue has directed state Emergency Management officials to take steps including:

Placing the North Carolina National Guard personnel on standby

Establishing coordination with the National Hurricane Center and National Weather Service

Bringing FEMA's coordinating officer into the Emergency Operations Center, which is standard practice.

Starting daily video teleconference calls with FEMA National and FEMA Region 4 (Southeast)

Checking and updating equipment at the Emergency Management warehouse (water, MREs, cots, blankets, portable toilets, sandbags and bagging machines, generators.)

Planning where to pre-position food, water and other supplies.

Making plans to activate the NCEM Regional Coordination Center in Kinston. The RCC coordinates with the counties to see what they need.

Ordering the State Emergency Response Team to activate Thursday morning. SERT is composed of all involved state agencies, private sector and volunteer organizations, such as: NCDOT, DENR, Agriculture, Commerce, utility companies, Red Cross and Baptist Men.

Begin checking with public water and wastewater treatment operations to see if they need assistance before or after the storm.

Developing 24-hour staffing plans through the weekend.

If needed, the Gov. is prepared to issue executive orders declaring a state of emergency, which allows the state to tap into federal resources to recover from the storm, and enacting other emergency measures to make it easier to restore power, remove debris and transport essential goods and services.
Copyright 2011 WECT. All rights reserved.

1 vote
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823. Gorty
Quoting Joshfsu123:
Folks, the TROF that may turn Irene to the NNE/NE is still over the Western United States or east of Alaska... still a day or two away from knowing how strong it will be and where it will set up.

If it sets up to the West, that will move the Hurricane NORTH (not NNE) into the Mid-Atlantic states. If it sets up a little east, Irene will move NNE and ride along the coast, potentially missing landfall.

Each run of the models will probably be different, west and east, over the next few days but two things are clear: there has been a trend eastward, meaning the TROF may be stronger, and we are still 4 days out - too soon to where she will go.

Better to be prepared.


Put nicely... but you left out the two hurricane models that are west the GFDL and HWRF.
Member Since: November 8, 2008 Posts: 12 Comments: 1058
Quoting KirbyPuckett34:
786. ncstorm 2:06 PM GMT on August 24, 2011

Please stop bashing the NHC..who would you rather have forecasting and predicting the path of the storm, the blog?? If that happened, Irene would have made a double loop over Florida, traveled to the Gulf and sat there and became a cat 6 in the "hot bath waters" and then hit NO and traveled back to Florida and rode up the entire east coast destroying NYC while poor Texas still didnt get any rain..I believe the NHC are doing a great job..

I couldn't have said it better myself. Don't understand why people hope for disasters


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.
Member Since: August 4, 2011 Posts: 0 Comments: 680
Quoting overwash12:
You listen to CoasttoCoast A.M. ,don't you? LOL


Not familiar with it
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Quoting Detrina:
Just popping in on a break at work. what is the latest on Miss Irene plz?
thanks:)


we're at WobbleCon level 4
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Quoting ncstorm:
Please stop bashing the NHC..who would you rather have forecasting and predicting the path of the storm, the blog?? If that happened, Irene would have made a double loop over Florida, traveled to the Gulf and sat there and became a cat 6 in the "hot bath waters" and then hit NO and traveled back to Florida and rode up the entire east coast destroying NYC while poor Texas still didnt get any rain..I believe the NHC are doing a great job..


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.
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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


Anything two weeks out is a guess not a forecast. Even those guessing can get it right sometimes.
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Just popping in on a break at work. what is the latest on Miss Irene plz?
thanks:)
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It's one thing to disagree with the NHC, but the bashing needs to stop. I agree about the Center line issue though, media tends to look only at that.
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Quoting BobinTampa:


Think your computer may be upside down.

Link


lol, it kept going west and west and west when it was supposed to have gone north, you know exactly what I'm talking about
Member Since: July 14, 2008 Posts: 2 Comments: 9689
Quoting HCW:
Do I need to issue a wobble watch warning ?
Were at just a wobble watch right now! Wobble Warnings may come later! :)
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Quoting ncstorm:
Please stop bashing the NHC..who would you rather have forecasting and predicting the path of the storm, the blog?? If that happened, Irene would have made a double loop over Florida, traveled to the Gulf and sat there and became a cat 6 in the "hot bath waters" and then hit NO and traveled back to Florida and rode up the entire east coast destroying NYC while poor Texas still didnt get any rain..I believe the NHC are doing a great job..


Brilliantly put!

Honestly, this is a Charley type forecast, in that it will be coming up just shy of parallel to the coast, so even a couple degrees difference can equal hundreds of miles difference in landfall. If this storm were coming perpendicular to the coast, the errors in the NHC forecast would appear far smaller.
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I think everyone should embrace the bickering and debate. A public that is engaged is a lot more likely to finance the research that may one day get a handle on Weather Forecasting.
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Quoting RitaEvac:


And it kept going west too didn't it


west-ish.
Member Since: Posts: Comments:
Folks, the TROF that may turn Irene to the NNE/NE is still over the Western United States or east of Alaska... still a day or two away from knowing how strong it will be and where it will set up.

If it sets up to the West, that will move the Hurricane NORTH (not NNE) into the Mid-Atlantic states. If it sets up a little east, Irene will move NNE and ride along the coast, potentially missing landfall.

Each run of the models will probably be different, west and east, over the next few days but two things are clear: there has been a trend eastward, meaning the TROF may be stronger, and we are still 4 days out - too soon to where she will go.

Better to be prepared.
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Glad S Fla is out of the cone of error....it'll be nice to go watch the 10-12 ft surf!!!!!!
will pray for the people in the path...good prep and heed the warnings please........
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Quoting Grandpato4:


I think I am going to stop even listening to the NHC. They have lost all credibility in my mind. I will pay attention maybe three days out from now on but no more following it five days or more out.


Obviously you aren't listening to the NHC very well at 5 days out. In their forecasts it states very well that 5 day forecasts can error 200-250 miles and that you should continue to check back in the days leading up to a possible landfall. The 5 day forecast gives you an idea of where it might go but it's not a guarantee nor intended to be.
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Quoting RitaEvac:


And it kept going west too didn't it


Think your computer may be upside down.

Link
Member Since: Posts: Comments:
NHC tropical cyclone forecast tracks can be in error. This forecast uncertainty is conveyed by the track forecast "cone", the solid white and stippled white areas in the graphic. The solid white area depicts the track forecast uncertainty for days 1-3 of the forecast, while the stippled area depicts the uncertainty on days 4-5. Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone about 60-70% of the time.
From the NHC...I think they do a great job!
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Member Since: Posts: Comments:
786. ncstorm 2:06 PM GMT on August 24, 2011

Please stop bashing the NHC..who would you rather have forecasting and predicting the path of the storm, the blog?? If that happened, Irene would have made a double loop over Florida, traveled to the Gulf and sat there and became a cat 6 in the "hot bath waters" and then hit NO and traveled back to Florida and rode up the entire east coast destroying NYC while poor Texas still didnt get any rain..I believe the NHC are doing a great job..

I couldn't have said it better myself. Don't understand why people hope for disasters
Member Since: Posts: Comments:
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’s Jet Propulsion Laboratory for many years. Hoagland’s 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. – via Glenn Kreisberg at http://www.grahamhancock.com/forum/KreisbergG2.php
You listen to CoasttoCoast A.M. ,don't you? LOL
Member Since: June 24, 2007 Posts: 0 Comments: 1498
954.5 mb
(~ 28.19 inHg)
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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.
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Quoting Zaphod:
The fervor about track shifts in the models is pretty funny. The NHC cone is 3 days long because that's how far the predictions are solid. The 5 day cone gets really wide because the predictions are poor.

Humans have a hard time dealing with probability, and the cone is notionally wide enough to cover 66% of the actual paths, so you can expect 1/3 to move outside it.

For this storm, maybe it's sometimes been in the 1/3 outside the early path, as the models shift east. But what does it matter if it's solidly wrong 5 days out?

Anyway, sometimes the atmosphere sets up so that paths are very sensitive to initial conditions, and that's what we've had. Seems like the consensus of models has quieted down lately, and the cone could probably be tightened a bit, but boy people would be surprised if the storm went from being an eastern outlier to a western outlier!


Weather is a chaotic process, and models will only ever get so good...probably could be better than they are, but with looming budget issues I wouldn't be surprised if we'll be stuck with this level of accuracy for a long time.


Nice explanation,just this time the cone was about 3000 miles wide !!!!
Irene has been moving to the east every single minute ,so is NOT RELIABLE AT ALL what models and the NHC showed with Irene's track.
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Quoting CarolinaHurricanes87:


I mean this is supposed to be the first hurricane to hit in 3 years and they are off by literally thousands of miles?


Actually not really. They say never truly look past three days out. AND in EVERY discussion that we read at the very end of it they say something along the lines of:

"Users are reminded that significant errors are possible with
forecasts at longer lead times...so one should not focus on the
exact forecast positions at 96 and 120 hours."

So how can anyone justify reading the "its possibly heading towards so and so city in five days" and then totally skip the last paragraph like it's not there and then be pissed when it doesnt verify.  That's true selective reading!
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Quoting ph34683:


That's interesting because Ocracoke is already being evacuated and it's in Hyde county.

And it's Currituck, not Carrituck.


Ocracoke has to be evacuated well ahead of any other evacs because of how long it takes to clear the island. They don't have the luxury of waiting for a hurricane watch to be issued.
Member Since: Posts: Comments:
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
Member Since: Posts: Comments:
13:45 UTC Image

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792. Gorty
Quoting aimetti:


can someone post these? im a noob


http://euler.atmos.colostate.edu/~vigh/guidance/n orthatlantic/track_early1.png
Member Since: November 8, 2008 Posts: 12 Comments: 1058
Quoting Zaphod:


Mr. Beeblebrox, do you have your towel?
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting gulfscout:


They said the whole time to be prepared just in case. Can you imagine the 4 mil + that evacuated from the metro houston area. Yet some of them were sorry when they brushed off the storm that came three years later.
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.
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I see no one downcasting irene for now.
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Anyone have recent observation data, that eye is increasingly looking super strong.
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IRENE via Eastern Cuba Radar Loop
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Please stop bashing the NHC..who would you rather have forecasting and predicting the path of the storm, the blog?? If that happened, Irene would have made a double loop over Florida, traveled to the Gulf and sat there and became a cat 6 in the "hot bath waters" and then hit NO and traveled back to Florida and rode up the entire east coast destroying NYC while poor Texas still didnt get any rain..I believe the NHC are doing a great job..
Member Since: Posts: Comments:
"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’s Jet Propulsion Laboratory for many years. Hoagland’s 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. – via Glenn Kreisberg at http://www.grahamhancock.com/forum/KreisbergG2.php
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Quoting BobinTampa:


of course, you thought Emily was headed west.


And it kept going west too didn't it
Member Since: July 14, 2008 Posts: 2 Comments: 9689
Quoting scCane:


Eyewall replacement cycle ahoy, still wobbling as it moves but right now still looks wnw.


That little stall right at the end is really easy to see.....interesting stuff.
Member Since: August 18, 2010 Posts: 14 Comments: 1606
Look up the history of 1960 hurricane Donna,after ravaging Florida,emerged back out to the east coast of Fl. came ashore at Topsail,N.C. as a cat 2 ,went up the coast hit long Island as a strong cat 1 90mph. So even if it hits N.C. it could still cause alot of damage all the way to N.Y. !
Member Since: June 24, 2007 Posts: 0 Comments: 1498
Quoting Gorty:


They are reliable and MUST be included as a possible track.


can someone post these? im a noob
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So NOAA just found 954.5 in the center - we'll have a vortex message in a few minutes. It's down a millibar or so over the last few hours. Still, I was hoping this storm would weaken a little as it plowed through the islands, and it's certainly not doing that.
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Quoting Grandpato4:
Governor just said they were not even considering coastal evacuations for any areas outside of Dare and Carrituck counties in NC. This is reassuring.


That's interesting because Ocracoke is already being evacuated and it's in Hyde county.

And it's Currituck, not Carrituck.
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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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