Hurricane Irene Prepares to Leave the Bahamas and Head for the US

By: Dr. Jeff Masters , 7:51 AM GMT on August 25, 2011

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As of 2AM EDT, Hurricane Irene was located at 24.2N, 76.0W, 105 miles east-southeast of Nassau or 760 miles south of Cape Hatteras. It was moving northwest at 12 mph with maximum sustained winds of 115 mph, making it a Category 3 storm on the Saffir-Simpson scale. Irene has a minimum central pressure of 950 mb. Hurricane force winds can be found up to 70 miles from Irene's center, and tropical storm force winds can be found out to 255 miles from the storm's center.

Hurricane warnings are in effect for all of the Bahamas. Hurricane and tropical storm watches will likely be posted for the Carolina coastlines later this morning. At this time, Dare County Emergency Management has issued a mandatory evacuation order for all visitors in their county. Dare County Schools will also be closed Thursday and Friday.

Satellite Views
Figure 1 is the infrared satellite image of Irene at 135EDT. The convection is a bit unbalanced around the storm center, which is going to cause Irene to wobble like an unbalanced clothes washer (Analogy courtesy of Angela Fritz) over the next few hours. At the time this image was taken, the convection around Irene's center appears to be getting more vigorous, as cold cloudtops are starting to increase around the storm center. This is important to note because microwave satellite imagery from Wednesday evening suggested Irene was starting an eyewall replacement cycle. Figure 2 shows passive microwave imagery from a Air Force DMSP polar-orbiting satellite. The two concentric green/yellow bands in the image suggest that two eyewall features are present in Irene, and Hurricane Hunter observations confirm this. This has important consequences for Irene's intensity, because in an eyewall replacement cycle, as the inner eyewall weakens, the storm's intensity drops. However, once the inner eyewall is gone, and the outer eyewall contracts to replace it, the storm intensity will increase again.


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


Figure 2 DMSP F18 microwave overpass of Irene at 824PM EDT, August 24, 2011. Image courtesy of the Naval Research Laboratory

Track Forecast

Irene is forecast to move to the northwest, passing over the northwest Bahamas by Thursday evening, then curving to the northeast. 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. Sunday, Irene may make secondary landfall anywhere from New Jersey to Long Island and the southern New England coastline. In my opinion, New York City may be significantly impacted by Irene. 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 Category 4 storm (winds faster than 130 mph) by Thursday morning. As Irene moves northward into cooler water, the intensity is expected to drop slowly to a Category 2 storm before making landfall in the Outer Banks.


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

Forecast models and today's planned flights
The different forecast models are still in fairly good agreement about Irene's track through the Bahamas and along the east coast of the US. The 00Z GFS run is in close agreement with the 12Z ECMWF run, but the 00Z ECMWF run (shown in figure 4) is continuing the ECMWF's trend of shifting the track westward with each run. NHC forecasters have been placing emphasis on the ECMWF's forecast track when making their forecasts for IRene, so it is possible that the NHC track will shift westwards at the 5AM update.

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 (Gonzo), and two flights for NOAA 42, a WP-3D (Kermit). They may have to give NOAA a littering permit for all of the dropsondes used to monitor Irene and her environment, but the forecast improvements they generate are worth the effort.


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

Impacts

Hurricane force winds will arrive in the northwestern Bahamas today. Storm surge near the center of Irene will be 7-11 feet above tide level. The Bahamas can expect 6-12 inches of rain over the next day or so, and it looks like the Turks and Caicos islands will receive a total of 6-12 inches from Irene. Large, swells from Irene will start landing on the southeastern US coastline later today. Please don't go in the water, as these swells can cause dangerous rip currents. Dr. Masters has catalogued the worst-case storm surge surge scenarios as a function of storm intensity here.

In my opinion, people living from the Carolinas to Cape Cod should pay close attention to Irene and prepare for a wide range of impacts. I think that there is a 75% chance of Irene's secondary landfall will be somewhere between JFK airport and Cape Cod. That said, Irene's size will cause significant impacts for people living far from it's center.

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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Good mid morning blog. We're getting close to finding out some things. Any more westward and the Northern NC coast and the Delmarva penisula gets a historic storm. Not to mention DC/Balt. That would help our Northern friends a bit and knock down the second strike. Either way, this is not a good story. I think we will be remembering Irene for a long time. Today is get things together day, tomorrow will be crazy.

Cat 5: You've been on this well for the last few days, still betting on the western landfall.
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she might slow down later today just as she leaves the northern bahamas now the time if she is to make cat 4 status
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Today, August 25, 2011, 12 minutes ago
August 25, 2011 7:50 am EDT
Location: 28.906N 78.471W
Wind Direction: ENE (70°)
Wind Speed: 23.3 knots
Wind Gust: 27.2 knots
Significant Wave Height: 13.1 ft
Dominant Wave Period: 12 sec
Average Period: 7.0 sec
Atmospheric Pressure: 29.80 in (1009.1 mb)
Pressure Tendency: +0.01 in (+0.3 mb)
Air Temperature: 84.4°F (29.1°C)
Water Temperature: 84.9°F (29.4°C)

This bouy is going to have a long day

Station 41010 - CANAVERAL EAST 120NM East of Cape Canaveral
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wonder what sepetember holds for tropial activity across the atlantic and gulf basins?

strange season for sure

other than Jose who looks to be going out to sea, nothing else to speak of
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Quoting cat5hurricane:

That's very near where I am projecting.


Well im in a tricky situation...the HURRICANE watch starts about 25-30 miles to my north...(Im in Wilmington) and now you guys are saying NC/SC border ?
Member Since: April 26, 2006 Posts: 5 Comments: 3222
What does this convert to (mph)?

859mb 65° (from the ENE) 117 knots (135 mph)
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Quoting tpabarb:
Why isn't Wilmington in a hurricane watch when NOAA tells me on my weather radio that we'll have hurricane force winds tomorrow? Actual question - anyone know?


If the NHC track at the 11am EDT update adjusts to compensate for the westward shift of the GFDL and GFDN models you may get put under a hurricane watch. We'll just have to wait and see how today unfolds
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435. 7544
morning all what time will irene be to the closest to so fla to the ne and could we see more than expected in so fla if the west wobbles start up again looking at the radar coming into viw looks like all rain tia
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Wow, here in West Palm Beach (26 miles inland) I was just sitting here waiting for the first of the outer bands to get here and out of nowhere the Sun just peeked through the clouds following a couple of light showers. Wasn't expecting to see that at all today.
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Eleuthera (pop. 8,000) getting hit now. Nassau (pop. 249,000) on the island to the west has dodged a bullet.



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tilted or eroded on sw side....
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Okay, am tapped out for the morning.
Will check in later for further news.
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Quoting TropicalXprt:
Getting the first of the bands here in Florida. Guess all the idiots saying fish storm were WRONG.


They were wrong when it hit PR
Member Since: July 27, 2011 Posts: 0 Comments: 204
ime: 12:11:30Z
Coordinates: 25.4N 76.55W
Acft. Static Air Press: 696.7 mb (~ 20.57 inHg)
Acft. Geopotential Hgt: 2,724 meters (~ 8,937 feet)
Extrap. Sfc. Press: 950.1 mb (~ 28.06 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 204° at 14 knots (From the SSW at ~ 16.1 mph)
Air Temp: 15.7°C (~ 60.3°F)
Dew Pt: 13.7°C (~ 56.7°F)
Peak (10s) Flt. Lvl. Wind: 20 knots (~ 23.0 mph)
SFMR Peak (10s) Sfc. Wind: -
SFMR Rain Rate: -
(*) Denotes suspect data
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426. Vero1
Quoting tpabarb:
Why isn't Wilmington in a hurricane watch when NOAA tells me on my weather radio that we'll have hurricane force winds tomorrow? Actual question - anyone know?

BULLETIN
HURRICANE IRENE INTERMEDIATE ADVISORY NUMBER 20A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011
800 AM EDT THU AUG 25 2011

WATCHES AND WARNINGS
--------------------
CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

THE GOVERNMENT OF THE BAHAMAS HAS DISCONTINUED THE HURRICANE
WARNING FOR THE SOUTHEASTERN BAHAMAS.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* THE CENTRAL AND NORTHWESTERN BAHAMAS

A HURRICANE WATCH IS IN EFFECT FOR...
* NORTH OF SURF CITY NORTH CAROLINA TO THE NORTH CAROLINA-VIRGINIA
BORDER INCLUDING THE PAMLICO...ALBEMARLE...AND CURRITUCK SOUNDS

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* NORTH OF EDISTO BEACH SOUTH CAROLINA TO SURF CITY NORTH CAROLINA

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA. A WATCH IS TYPICALLY ISSUED 48 HOURS
BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL-STORM-FORCE
WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT OR
DANGEROUS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

INTERESTS ELSEWHERE IN THE MID-ATLANTIC STATES AND NEW ENGLAND
SHOULD MONITOR THE PROGRESS OF IRENE.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE.
FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE
THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.


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Quoting WxLogic:


Not quite... but would support a longer NW heading (to WNW at times) before NNW could materialize.


Her westward component is becoming less and less. Having said that, I still believe she could make it as far W as the NC/SC border. Right at the tip.
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Good morning from the sunny Outer Banks (OBX) of NC. The way I see it using the GRILL forecasting method, it I situated my grill on a N/S axis, I'm ok, but if I turn it E/W, than than I am in the latest path. fyi, no locals I can find are leaving at this point. They have made evacuation mandatory for our guests (+ or - 200K), but the locals are staying put, as it is forecast as a CAT 2. Would you go? Storm surge is 6 to 8 feet, we are a sandbar, but a fairly hilly one with maritime forests, CCC dunes, and some well known areas,which seem to flood often. So would you go? I need to make the call by 11:00 am, if I am to get help leaving. I am leaning toward staying.
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Quoting Skyepony:
What is that on the SSE side there at the end of MIMIC?


Government secret project to push Irene into the carolina's in order to save the North East....

Member Since: July 27, 2011 Posts: 0 Comments: 204
The storm is now 230 miles due east of Miami
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we can say adios to Jose once it goes out to sea
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Irene further away from the Carolinas under hurricane watches but closer to FL under nothing
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417. HCW

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416. Skyepony (Mod)
What is that on the SSE side there at the end of MIMIC?
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Why isn't Wilmington in a hurricane watch when NOAA tells me on my weather radio that we'll have hurricane force winds tomorrow? Actual question - anyone know?
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ametti:i grew up in ledyard and was their for gloria and bob,trees will go down,power will go out,basements will flood,run from the ocean and hide from the wind,make sure your sub-pump works and take refuge in your basement,falling large trees are deadly when they fall on your house,listen to your local emergency managment for evacuation zones and instructions,god bless and stay safe..oh yea make sure you have enough supplies to be without food and water for 5-7 days!!
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Quoting Skyepony:
90L got declared..TD10 is born.
the weaker waves are the ones to be watching now
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Member Since: July 3, 2005 Posts: 427 Comments: 129457
Quoting MahFL:
Doesn't a bigger eye usually mean a larger windfield ?


Wilma had a tiny eye and a huge windfield
Member Since: July 27, 2011 Posts: 0 Comments: 204
409. Vero1
Quoting Skyepony:
90L got declared..TD10 is born.

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU AUG 25 2011

THE 1007 MB LOW CENTERED SW OF THE CAPE VERDE ISLANDS WAS
UPGRADED TO TROPICAL DEPRESSION TEN AT 0900 UTC. TROPICAL
DEPRESSION TEN IS CENTERED NEAR 12.4N 30.4W AT 25/0900 UTC
MOVING W-NW AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007
MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT.
PLEASE SEE THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADER
MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. T.D. TEN COULD BECOME A
TROPICAL STORM LATER TODAY.
SCATTERED MODERATE/STRONG CONVECTION
IS WITHIN 75/90 NM OF LINE FROM 16N28W TO 13N33W. SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS COVER THE REMAINDER
OF THE AREA FROM 9N-13N BETWEEN 30W-35W.

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Quoting cat5hurricane:

It would almost be a blessing to NYC then, as it would be considerably weaker. One would have to image. I guess barring it jogs NE back over the open water before shifting NNW then. A double-whammy so to speak. That's a doom scenario, and unlikely.

I suppose it all depends on location. If Irene can manage to keep her eye mostly offshore--or if her eye is only inland over the OBX for a short time--and if she moves just fast enough that she doesn't experience rapid cooling, she'll have plenty of steam left over for the NYMSA--not to mention that she'll be pushing a pretty wide wall of water on her right side, and that'll have nowhere to go when it reaches Long Island and Cape Cod.
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407. MahFL
Doesn't a bigger eye usually mean a larger windfield ?
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She has a pinhole eye!

Well, no not Irene....,this storm
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Member Since: July 3, 2005 Posts: 427 Comments: 129457
Re: #398.
Wow N. You get a double gold star for helpful links this morning! These are great, thanks!
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402. Skyepony (Mod)
90L got declared..TD10 is born.
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Link


Photos from Crooked Island
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Irene does not need to go any farther W for the sake of S/N Carolina and farther N up the East Coast. Hopefully it wont get as intense as some of the models are showing.
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Quoting MahFL:



So on that steering it's going to Florida ?


Not quite... but would support a longer NW heading (to WNW at times) before NNW could materialize.
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Another page to reference for those potentially in harms way:

TROPICAL CYCLONE IMPACTS - DECISION SUPPORT
Member Since: September 23, 2005 Posts: 14 Comments: 11307
Quoting 900MB:
Funk finding some green again
Link

Yeah, she seems to be finding her footing again after her expected EWRC stumble...
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Quoting TropicalAnalystwx13:
Severe damage reported in the Bahamas, near Crooked Island.
Link
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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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