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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guys if you are going wave watching on the beach un les they have it close plzs where a life jacket so that way if a wave comes up and take you at too sea the life jacket will keep you a float in tell help comes



life jacket can save your life plzs ues it and ware it and stay safe at the same time
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Quoting CosmicEvents:
Once she got away from the Bahamas her COC had been disrupted and it's never been able to tighten up again.
Eye/Eyewall formation has been a problem for Irene through out her life cycle.
Even as a cat 2/3 she's had difficulty forming a well developed eye/eyewall.

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Doesn't look that weak to me. Looks stronger on each frame

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298. SLU
Quoting TropicalAnalystwx13:
Yeah, this really qualifies as a tropical depression :\



Not normal to see a tropical cyclone struggle like this near the Cape Verdes in late August.
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Quoting TropicalAnalystwx13:
Yeah, this really qualifies as a tropical depression :\


What in the world happened to it?!
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Has the Wunderground KMZ file been updated lately?
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295. yoboi
is something forming south of cuba?
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Sorry to use caps, but CAN SOMEONE PLEASE LINK TO THESE WEBCAMS PEOPLE ARE TALKING ABOUT? Thank you. Maybe 3rd time I'll get a response.
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Quoting TropicalAnalystwx13:


Yup...according to the models, this should've been in the Gulf of Mexico.
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]

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I am a RN with the Red Cross here in Fla., they are saying there is a massive need for response from our region to help out up there.
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Quoting HurricaneDean07:
How you doing TAWX, conditions still okay


Pouring down rain, gusty, but still good for now.

15-20 mph sustained, 25-35 mph frequent gusts, and 40-50 mph infrequent gusts (in strong bands).

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290. AVL
Any one that would like to chime in on this it is appreciated.

Last night the issue was pressure drop and winds not catching up. The general concensus was that the storm was using the drop (Energy?) to increase in size. Now that she is smaller, injected with dry air, and pressure is dropping will it make it easier for the wind speeds to correlate with pressure drop?
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Yeah, this really qualifies as a tropical depression :\

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How you doing TAWX, conditions still okay
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286. JLPR2
In 96hrs the GFS develops lows with both of this disturbances getting ready to emerge from Africa.



The action doesn't end with Irene.
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Quoting victoriahurricane:
Does anyone have a link to a webcam with sound showing Irene's waves at a beach somewhere close to landfall expectations?




7674u.com
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storm surge starting to come in http://grandstrandcams.com/webcameras-oceans-one-b ar-harbor.php
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The percentage of "Downgradecassters," has dropped off a bit lately?
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Quoting NICycloneChaser:


Look at that cam, then tell yourself that Irene's centre is 175 miles away from there. Massive storm.


Yeah, just make me feel bad! lol.
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Quoting Dennis8:


Sorry for your loss in Katrina...


As well for you ,,in IKE.

Calamity knows no borders'..
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Quoting Stormchaser2007:


Amazing what dry air can do.

Cavitation? LOL!
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Quoting Stormchaser2007:


Amazing what dry air can do.
That trek through the Bahamas loosened up and disrupted her COC and it's never been able to tighten up again.
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Quoting Olivia1001:
pensacoladoug,

what is the link to follow OZ?
7674u.com
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Quoting bohonkweatherman:
In about a week the Strong High Pressure over Texas is suppose to Split and be out of Texas, relief but also opens Texas up for tropical systems IMO.


YES it willl
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All the birds in New York are gone. Its dead silent out here in Westchester county. Also why hasn't anyone boarded up their windows?
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Quoting TropicalAnalystwx13:
One webcam view from Wrightsville Beach, North Carolina. You could probably find a better one. Anybody know of one?

Link


Look at that cam, then tell yourself that Irene's centre is 175 miles away from there. Massive storm.
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if you follow this 12 hour loop you can tell there is slight strengthening at the end.

Link
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Quoting atmosweather:


Chances are low but far from impossible. With the way she looks now she's certainly running out of time to do so.


Thank you!
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Quoting Patrap:


No,,but I've friends in Galveston across from JSC.

Im in NOLA.


Sorry for your loss in Katrina...
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Quoting TropicalAnalystwx13:


You're wrong..I only see 1 pixel of red.

LOL!


Stop being so pixy! There were 2 there a few minutes ago. Looks like it wants to come back a little. Looks a litle better than 1/2 hour ago.

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Storm Relative 1km Geostationary Visible Imagery

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Quoting Stormchaser2007:


Amazing what dry air can do.


I love dry air!!!!
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Quoting TropicalAnalystwx13:
One webcam view from Wrightsville Beach, North Carolina. You could probably find a better one. Anybody know of one?

Link


Try SurfChex.com Some issues with it connecting to the server. They have a few other cams on the outer banks as well.
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Quoting Levi32:
No -70C tops...if you want to be picky there's 2 pixels of red lol. It's a rather pathetic looking IR presentation of a Cat 2 hurricane.



Amazing what dry air can do.
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Sounds like Dennis Rygaard
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263. JLPR2
GFS is showing consistence in developing a system SE of the CV islands.

18Z GFS, 3days out...


Now, according to the model, that should be Jose.
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Quoting Dennis8:


Are you in Bolivar? I lost a home and business there.


No,,but I've friends in Galveston across from JSC.

Im in NOLA.
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Quoting Patrap:
Houston wasnt Bolivar by a lonnnnnng shot.



I also had a home damaged on Tiki island...do we know each other?
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One webcam view from Wrightsville Beach, North Carolina. You could probably find a better one. Anybody know of one?

Link
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09L/H/I/C1
RI FLAG (off)
RD FLAG (OFF)
WEAKENING FLAG (FLAG)
MARK
33.55n/76.9w forecast point





ALWAYS FOLLOW NHC/TPC FORECASTS FOR ALL WARNINGS REGARDING THIS STORM
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4:50 pm NE 40.8 50.5 23.6 16 9.2 ESE 29.36 -0.24 76.5 82.9 76.3 - - -

Bold items are Windspeed (kts), Gust (kts), and Waveheight at the buoy @ Frying Pan Shoals. This is 50 miles due south of Wilmington, NC.
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Quoting Patrap:
Houston wasnt Bolivar by a lonnnnnng shot.



Excellent quote
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Quoting AstroHurricane001:
For better or for worse, long-range computer model forecasts a week ahead show a strong high pressure system centered over Eastern Canada and a trough in the central CONUS. This could drive some hurricane tracks toward South Florida, Louisiana or say, Texas, especially as several highs are seen drifting from the Arctic regions toward eastern North America on the longest-range runs.
In about a week the Strong High Pressure over Texas is suppose to Split and be out of Texas, relief but also opens Texas up for tropical systems IMO.
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Quoting Patrap:
Houston wasnt Bolivar by a lonnnnnng shot.



Are you in Bolivar? I lost a home and business there.
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TD 10 bust how evere we sould still watch it down the road may be it will come back too life later
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Quoting Levi32:
No -70C tops...if you want to be picky there's 2 pixels of red lol. It's a rather pathetic looking IR presentation of a Cat 2 hurricane.



You're wrong..I only see 1 pixel of red.

LOL!
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NOAA airplane is ringing in with 949mb extrapolated pressure. Another vortex message should be out shortly. Winds north of the eye are still below 100kts at flight-level, weaker than earlier.
Member Since: November 24, 2005 Posts: 635 Comments: 26700

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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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