Irene continues to weaken

By: Dr. Jeff Masters , 8:46 PM GMT on August 26, 2011

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Satellite data and measurements from the Hurricane Hunters show that Irene continues to weaken. A 1:32 pm EDT center fix by an Air Force Reserve aircraft found that Irene's eyewall is still gone, and the central pressure had risen to 951 mb from a low of 942 mb this morning. The winds measured in Irene near the surface support classifying it as a strong Category 1 hurricane or weak Category 2. Satellite imagery shows a distinctly lopsided appearance to Irene's cloud pattern, with not much heavy thunderstorm activity on the southwest side. This is due to moderate southwesterly wind shear of 10 - 20 knots. This shear is disrupting Irene's circulation and has cut off upper-level outflow along the south side of the hurricane. No eye is visible in satellite loops, but the storm's size is certainly impressive. Long range radar out of Wilmington, North Carolina, shows that the outermost spiral bands from Irene have moved ashore over North Carolina. Winds at buoy 41004 100 miles offshore from Charleston, SC increased to 47 mph, gusting to 60 mph at 3 pm EDT, with significant wave heights of 25 feet.


Figure 1. MODIS satellite image of Hurricane Irene taken at 11:50 am EDT Friday August 26, when Irene was a Category 2 hurricane with 105 mph winds. The eyewall collapsed several hours before this image was taken, and no eye is apparent. Image credit: a href=http://rapidfire.sci.gsfc.nasa.gov/gallery/ NASA.


Figure 2. Distribution of Irene's wind field at 3:30 pm EDT Friday August 26, 2011, as observed by the Hurricane Hunters and buoys. The right front quadrant of the hurricane had about 90% of the storm's hurricane-force winds (yellow and warmer colors, bounded by the heavy black line between the "50" and "60" knot thin black lines.) Tropical storm-force winds (heavy black like bounding the light blue area) extended out 290 miles from the center of Irene. Image credit: NOAA/AOML/HRD.

Forecast for Irene
With its eyewall collapsed and just 18 more hours over water before landfall, Irene does not have time to build a new eyewall and intensify. The storm is too large to weaken quickly, and the best forecast is that Irene will be a strong Category 1 hurricane at landfall in North Carolina on Saturday. Based on the latest wind analysis from NOAA's Hurricane Research Division (Figure 2) and Irene's continued weakening trend, I predict that the 80-mile section of North Carolina coast to the right of where Irene makes landfall will receive sustained hurricane-force winds of 75 - 85 mph on Saturday at landfall; the 80-mile section of coast to the left will receive 55 - 75 mph winds. High wind shear of 30 knots will begin ripping into Irene Sunday morning when it is near Southern New Jersey, and more rapid weakening will occur. By the time Irene arrives on Long Island Sunday afternoon, it will probably have top sustained winds in the 65 - 75 mph range. However, since Irene is such a huge storm--tropical storm force winds extend out up to 290 miles from the center--it has set a massive amount of the ocean's surface in motion, which will cause a much larger storm surge than the winds would suggest. At 3:30 pm EDT this afternoon, a wind analysis from NOAA/HRD (Figure 2) indicated that the potential storm surge damage from Irene still rated a 5.0 on a scale of 0 to 6. This is equivalent to the storm surge a typical Category 4 hurricane would have. While this damage potential should steadily decline as Irene moves northwards and weakens, we can still expect a storm surge one full Saffir-Simpson Category higher than Irene's winds when it impacts the coast. Since tides are at their highest levels of the month this weekend due to the new moon, storm surge flooding will be at a maximum during the high tidal cycles that will occur at 8 pm Saturday night and 8 am Sunday morning. Wherever Irene happens to be at those times, the storm surge damage potential will be maximized. I continue to give a 20% chance that a 3 - 4 foot storm surge high enough to over-top the Manhattan flood walls and swamp the New York City subway system will occur on Sunday. The latest 11 am probabilistic storm surge map from NHC shows a 20 - 30% chance of a storm surge in excess of 3 feet in New York Harbor (Figure 4.) Keep in mind that these maps are calculated for normal tide level, and this weekend's high tides will be nearly 1 foot above normal.

Insurance company AIR-Worldwide is estimating that insured damages from Irene in the U.S. will be $1.5 - $6 billion. They estimate losses in the Caribbean at $0.5 - $1.1 billion from Irene.


Figure 3. Storm surge heights, in feet above normal tide level, which have a 20 percent chance of being exceeded during the next 3 days.  The graphic is based upon an ensemble of Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model runs using the current National Hurricane Center (NHC) official hurricane advisory. The exceedance heights depend on the historical accuracy of NHCs forecasts of hurricane track, and wind speed, and an estimate of storm size. Image credit: NOAA.


Figure 4. Overall chance that storm surges will be greater than 3 feet above normal tide levels during the next 3 days.  The graphic is based upon an ensemble of Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model runs using the current National Hurricane Center (NHC) official hurricane advisory.  Storm surge probabilities depend on the historical accuracy of NHCs forecasts of hurricane track, and wind speed, and an estimate of storm size. Image credit: NOAA.

Links
For those of you wanting to know your odds of receiving hurricane force or tropical storm force winds, I recommend the NHC wind probability product.

Wunderground has detailed storm surge maps for the U.S. coast.

The National Hurricane Center's Interactive Storm Surge RIsk Map, which allows one to pick a particular Category hurricane and zoom in, is a good source of storm surge risk information.

Wunderblogger Mike Theiss is in Nassau, documenting the storm's impact on the Bahamas.

Internet radio show on Irene at 4:30pm EDT
Wunderground meteorologists will be discussing Hurricane Irene on a special edition of our Internet radio show, the Daily Downpour, today (Friday) at 4:30pm EDT. Shaun Tanner , Tim Roche, Angela Fritz, and Rob Carver will take your questions. The email address to ask questions is broadcast@wunderground.com.

Jeff Masters

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Quoting JLPR2:


You need to upload the image elsewhere or else it wont be visible to others.
Models that far out have a lottery chance of being right. Is this a case of wish casting I think so.
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500. JLPR2
Quoting RitaEvac:
WTH is this...



According to the GFS that's Katia.
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Quoting TropicalAnalystwx13:


A moderately deep disturbance in the baroclinic atmosphere located in the western Central Gulf of Mexico???


Seen in to many times...
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Quoting drg0dOwnCountry:
Running outside in the dark during a hurricane does not sound very clever anyway :)


lol, it isn't dark yet...And the winds aren't necessarily hurricane force yet. ;)
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Quoting JLPR2:


You need to upload the image elsewhere or else it wont be visible to others.
Thats on 9-11
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496. 996tt
Quoting RitaEvac:
WTH is this...



Surfs up. Means won't have to drive to East Coast . . . Seriously, what is that?
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Quoting RitaEvac:
WTH is this...



A moderately deep disturbance in the baroclinic atmosphere located in the western Central Gulf of Mexico???
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Look at the contrast from Aug. to Sept. in the GOM, of course this is based off Climatology and may not be the pattern we see coming up.







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Storm Relative 1km Geostationary Visible Imagery

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Quoting bwat:
Bastardi is a NE wishcaster, also its easy to be right about a storm forming when you claim every wave and disterbance in the atlantic is gonna form. Him and that whole sight is about hits and advertising. Go over there right now, but before you can click on a forecast a huge flash add pops up over the screen.
You don't have 1% percent of his talent. Truth hurts.
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490. ADCS
Quoting TropicalAnalystwx13:
I think she made progress with her eyewall..





Dreaded pinhole?
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Quoting TropicalAnalystwx13:
Yeah, well, I went outside to get video of the wind and it decides to stop.

:\
Running outside in the dark during a hurricane does not sound very clever anyway :)
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488. 996tt
Quoting weatherwart:
Hot and dry in Florida today. Irene sucked all the moisture right out as she went by.


Oh my God its hot. Destin supposed to 95 or 96 tomorrow. GOM tropical system would be horrendous news as it has been hot this summer and the Gulf is primed.
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485. 900MB
2 frames further(30mins) looks better!
Member Since: June 11, 2006 Posts: 0 Comments: 684
WTH is this...

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Quoting TropicalAnalystwx13:


lol, she didn't want to get caught in her ugly state. Hopefully, she won't have enough time to become "pretty".

LOL

She's so self-centered...
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EYEWALL might be re-forming. Last frame on the rainbow shows cloud tops getting colder which is evident by the deeper reds showing up. Then you see a hole in the middle of the storm where the cent er is.

Hard to say it is the eye but we could be in form her making a come back

Link
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Quoting TropicalAnalystwx13:
I think she made progress with her eyewall..



i agree... last frame and a burst of covection on inner core
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It would be interesting to test prior year(s)Gulf Loop Current/ Eastern Gulf upwelling/perturbation against subsequent intensities. My list of Loop Current Crossers (hurricanes only): 1998-Earl (minimal Hurricane) Georges-(the unheeded warning to NO-75 miles east of being Katrina) 1999-Brett (not really a loop storm but I am in a generous mood); 2000 Gordon (lame-o storm); 2001-None; 2002-Lilli (long tracker-western edge of loop); 2003-Claudette (even further west-See Brett); 2004-Charley (You sick freak meso-blowup in the hot shallows of FL Gulf Coast), Ivan-tips off the loop current barrage in 2005 with Katrina, Rita, Wilma (I stayed up all night in disbelief watching this pinhole). If you really want to get picky, you go from 1998 to 2004, Ivan, before an intense cyclone taps the really hot water of the Eastern Gulf. When the steering currents finally started dumping closed circulations into the eastern gulf at the end of 2004, the SST was way hot and probably deeply saturated. The 2004-2005 blowup was focused regionally in the eastern Gulf which probably not coincidently was an unplowed, overheated, fertile breeding ground for some high energy events.
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Quoting TropicalAnalystwx13:
I think she made progress with her eyewall..


0_o
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Quoting WeatherNerdPR:

She's EVIL!


lol, she didn't want to get caught in her ugly state. Hopefully, she won't have enough time to become "pretty".

LOL
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I think she made progress with her eyewall..



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Quoting TropicalAnalystwx13:
Yeah, well, I went outside to get video of the wind and it decides to stop.

:\

She's EVIL!
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Quoting Xyrus2000:


Are you aware that NONE of your images are showing up? Stop trying to hotlink to their site. Follow the information in the graphic.


They do show for the poster, that's why he didn't know.
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473. JLPR2
Quoting wunderweatherman123:

384 hours out we have a hurricane in the Gulf of mexico from the tropical storm in the bay of campeche and tropical storm in the carribean. both of them combined to become a hurricane. in this run the hurricane is moving due north towards lousiana. Credits to the 18z GFS.


You need to upload the image elsewhere or else it wont be visible to others.
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5 storms and 1 depression in August? Pretty impressive, and we still have 5 days left.
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Hot and dry in Florida today. Irene sucked all the moisture right out as she went by.
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Irene's eye is back!
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Quoting BahaHurican:
Except for every 4th run, which showed it taking pretty much the track it is now, and every other 4th run, which showed it going up the middle of FL.... and....

Well you get my drift. 240hrs is trend, not the end.

But 3 days out is the bomb. NHC track through here was almost exactly correct by Tuesday, with only slight modulations due to trocchoidal wobbling. I think we are getting better, slowly yes, but better. NHC will get its 7-day forecast eventually [though not, I expect, any time soon... lol]



Baha, lets not forget the unprecedented amount of resources that were thrown at this storm. The track forecast is only a reflection of the large amount of data collected over a very large geographical region. Unfortunately, this is not, and will not, be the case with every storm . . .
BTW, you don't know me but happy to hear that you are doing fine (exception of the power/phone outages).
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Bought a membership, best money spent, love the radar loops. Didn't know it would reset my post count, but worth it!
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Quoting bwat:
Bastardi is a NE wishcaster, also its easy to be right about a storm forming when you claim every wave and disterbance in the atlantic is gonna form. Him and that whole sight is about hits and advertising. Go over there right now, but before you can click on a forecast a huge flash add pops up over the screen.


yeah... Elliott Abrams is just about the only one worth listening to on that site. His video blogs are great. The rest of them tend to focus on extremes. But nobody should talk down about Elliott.
Member Since: November 17, 2010 Posts: 11 Comments: 527
It's times like this I am reminded of one of my favorite phrases after reading the blog throughout the day and realizing my ignore list went up an additional 25 more people.

"There is no cure for Stupidity"
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Quoting DontAnnoyMe:


Nobody but you can see the pics; remote linking has been disabled on that site.


But you can view the image this way: copy the image location, open another tab or window, and paste it there.
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Quoting wunderweatherman123:

384 hours out we have a hurricane in the Gulf of mexico from the tropical storm in the bay of campeche and tropical storm in the carribean. both of them combined to become a hurricane. in this run the hurricane is moving due north towards lousiana. Credits to the 18z GFS.


Are you aware that NONE of your images are showing up? Stop trying to hotlink to their site. Follow the information in the graphic.
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Yeah, well, I went outside to get video of the wind and it decides to stop.

:\
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Quoting wolftribe2009:


I disagree with that this storm is a dud. It might not be a CAT 2 when it reaches the city but it will be pushing a wall of water along it's path into the city. It might not be as high as it could have been had the storm not weakened but it will still be a large swell.

to0 funny when you have to swim to the closed store come chat then and they say it's just the cast of jersey shore that acts like that
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Irene is frail inject some hot water
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Quoting goldenpixie1:
Quoting PureScience:
"I am just a high school drop out but I can't help but wonder why we even spend a dime sending Hurricane Hunters into storms to get precise measurements when the guys and gals with the degrees resort to assumptions and guesses of the storms intensity when they don't get readings to support their hype."

My thought on that is that the planes go out and take readings. The data they bring back is then interpreted. Part of the interpretation would also include data from other sources. Then an reasonable conclusion is drawn.

Not all weatherman see the same things when looking at their data and some have more experience than others. Some go with pure data, some add in their gut feeling. It's not an exact science. That's why you see statements that are a bit vague or hedging. IMO.


That probably is exactly how it is done in Communist China. But we don't 'cotton-to' Command and Control government prouncements. In a democracy everyone has the opportunity to speak out. It is my job to separate the wheat from the chaff.

And laugh a little about how freedom isn't so free sometimes.
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Quoting ProgressivePulse:
NAO went moderately positive today folks. Look for more ridging on the east coast and west tracks after Irene's passing, assuming it holds positive.

25Aug2011 -0.62453E+00
26Aug2011 0.48188E-01
its expected to be neutral postive until september
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Quoting twincomanche:
He will eat those words.


Yea I believe the GOM is a sitting duck this year. I just can't imagine a hurricane season like this one without one in the gulf. The pattern changed in mid august which has opened the door more for the eastern gulf. I expect the Texas high to back westward in September and that is when I think we will have to watch the GOM.
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Quoting ProgressivePulse:
NAO went moderately positive today folks. Look for more ridging on the east coast and west tracks after Irene's passing, assuming it holds positive.

25Aug2011 -0.62453E+00
26Aug2011 0.48188E-01


Me no like.
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456. bwat
Quoting wxmobilejim:

he has been right about Irene from a week before she formed so I would say he lost his mind. He was saying east coast when everyone else was saying gulf then Florida.
Bastardi is a NE wishcaster, also its easy to be right about a storm forming when you claim every wave and disterbance in the atlantic is gonna form. Him and that whole sight is about hits and advertising. Go over there right now, but before you can click on a forecast a huge flash add pops up over the screen.
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I think the NNE motion was a wobble (Irene is wobbly) due to the recent uptick of convection on her NE semicircle.
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NAO went moderately positive today folks. Look for more ridging on the east coast and west tracks after Irene's passing, assuming it holds positive.

25Aug2011 -0.62453E+00
26Aug2011 0.48188E-01
Member Since: August 19, 2005 Posts: 5 Comments: 5451

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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.