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 GatorWX:
Levi, Pat, whomever knows,

Do you think this trough will keep her on a more easterly heading as is evident on satellite and hh fixes or do you suppose she could bend back left as the current trough moves out?


I personally think the latter.
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Quoting floodzonenc:


That's what she said?


I am now profoundly disappointed I didn't invoke innuendo first. I consider myself quite the pervert.
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1500. GatorWX
Levi, Pat, whomever knows,

Do you think this trough will keep her on a more easterly heading as is evident on satellite and hh fixes or do you suppose she could bend back left as the current trough moves out?
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1499. 900MB
Quoting thelmores:
Seems obvious to me that Irene will "skirt" the outer banks, and is far right in track in most if not all models....... will be interesting to see what Irene does when she rounds the Hatteras bend..............



You've got a point there! If she gets one more little burst and misses most of NC, worse for Long Island and NE.
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Quoting wolftribe2009:
do any of you know where I can get some webcam of the storm conditions in NC right now? I can't seem to find any.
Quoting Remek:


Try this one:

Link


Wow
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Quoting KoritheMan:


Norcross is always on top of things.
I spent some time the other night watching him on old Andrew footage (clips from several days out thru brodcasting-from-the-bunker). Gave me a new appreciatoin for him. Seems like a genuinely nice guy.
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Quoting hahaguy:


The only one there who actually knows what he's talking about.


I like Knabb as well. Remember, like Hope, he is a former hurricane specialist.
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http://i52.tinypic.com/2nrhgdl.jpg
Zoomed Water Vapor image with Irene, L/L, and Tropical Forecast Points. Clearly well east of it already and if this NE movement continues she will miss the next one also.
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Quoting cindyker:

Reposting for those asking: Topsail Webcam , NC


The cam is awesome! Thanks! Those are some angry waves for sure.
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norocross mentioned the 11pm adivsory 100mph wind 951mb NNE at 13mph i believe
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Thanks for all pics Tigger, and great job getting them posted. Stay safe!
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1489. njdevil
76.9? What was the 8PM position as E/W goes?
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Stay safe TWA13!



000
URNT12 KNHC 270254
VORTEX DATA MESSAGE AL092011
A. 27/02:34:10Z
B. 32 deg 32 min N
076 deg 52 min W
C. 700 mb 2679 m
D. 66 kt
E. 086 deg 44 nm
F. 171 deg 91 kt
G. 087 deg 67 nm
H. 952 mb
I. 10 C / 3051 m
J. 15 C / 3049 m
K. 11 C / NA
L. NA
M. NA
N. 12345 / 7
O. 0.02 / 1 nm
P. AF308 2909A IRENE OB 20
MAX FL WIND 108 KT SE QUAD 22:47:20Z
DROPSONDE RELEASED NEAR MAX FL WIND INBOUND RECORDED 79 KTS AT SPLASH PT
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting TropicalAnalystwx13:
Good night guys, will report on conditions tomorrow morning, if possible.


Have a great night and stay safe! Hopefully things don't end up being too bad in your neck-of-the-woods.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
@TStormSC: Vinegar works on skunk smell, too. I've set it out in bowls when skunks go off outside my window - it takes a while but it works. Not sure how it would be for dogs, though. :-( Acidic, so not good for their skin.

Best of luck!
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1484. 7544
irenes moving east no models were showing is she trying to go a round the high and turn around wouldnt that be a big surpise k just like emily did is that possible the way the high is place now just asking lol
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Quoting KoritheMan:


Norcross is always on top of things.


Certainly is.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Good night guys, will report on conditions tomorrow morning, if possible.
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Quoting AllStar17:
Norcross is on top of things. He mentioned that veer to the right...and said models did not depict that.


Quoting P451:


Moving exactly as forecast.

Improved organization exactly as modeled earlier this morning.

Pretty impressive score for the models here. All that data gathered by those scores of flights and the weather balloon launches really paid off here.




So have the models performed well or not?
Just curious here, not looking to cause an argument
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Irene's intensity is pretty much the same. Only up 1 mbar.
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Quoting thelmores:
Seems obvious to me that Irene will "skirt" the outer banks, and is far right in track in most if not all models....... will be interesting to see what Irene does when she rounds the Hatteras bend..............



I agree.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Quoting hahaguy:
Cool pics tigger.


our biggest problems were super high tides and some power outages...i did NOT venture to Folly Beach where Press was...last time it flooded there from some rain it was SUPER deep...wasn't taking the chance with little one...i was nervous enuf going down town...water sits on roads some but these tides were higher than my hubby even remembers and he is from here and use to LIVE down town...
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Quoting beell:


Yup, based on an amateur 500mb height analysis of recon-she will be east of OBX. No landfall in NC.

Crow standing by...!
I would warm that pan up if I were you...don't think she will pass East of OBX.
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1476. GatorWX
Levi, Pat, whomever knows,

Do you think this trough will keep her on a more easterly heading as is evident on satellite and hh fixes or do you suppose she could bend back left as the current trough moves out?
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1475. hahaguy
Quoting KoritheMan:


Norcross is always on top of things.


The only one there who actually knows what he's talking about.
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This is ridiculous but not surprising...
With Hurricane Bearing Down Eric Cantor Says Disaster Relief Should Be Paid For With Spending Cuts

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Seems obvious to me that Irene will "skirt" the outer banks, and is far right in track in most if not all models....... will be interesting to see what Irene does when she rounds the Hatteras bend..............

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Hi Patrap--it's Fred who came to your intro course four years ago.. In Bangkok watching tropical monsoon conditions. Seems Irene is a real wet blanket, winds low and rains too high.
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1471. Levi32


The line of white moisture through Michigan is the front that will be helping to pick up Irene and enhance rainfall heavily as she moves up into the mid-Atlantic.

Member Since: November 24, 2005 Posts: 635 Comments: 26652
Quoting AllStar17:
Norcross is on top of things. He mentioned that veer to the right...and said models did not depict that.


Norcross is always on top of things.
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1469. 900MB
Quoting MahFL:
The center of Irene is now shaped like an S.


She is just trying to let you know that she is a "Superstorm", watch out :)
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Quoting P451:


Moving exactly as forecast.

Improved organization exactly as modeled earlier this morning.

Pretty impressive score for the models here. All that data gathered by those scores of flights and the weather balloon launches really paid off here.



Moving east of the next forecast point.
Link
Member Since: June 29, 2009 Posts: 13 Comments: 5313
1466. hahaguy
Cool pics tigger.
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Norcross is on top of things. He mentioned that veer to the right...and said models did not depict that.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
1463. ncstorm
Tornado warning issued - radar showed a tornado 19 miles southeast of Main Gate at Camp LeJeune moving northwest at 50 mph in Onslow County
Member Since: August 19, 2006 Posts: 13 Comments: 15666
Fantastic PIC tigger.. glad you figured it out!! keep them coming!!
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The Cape is going to take it on the chin!
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1459. gecko
Quoting TStormSC:
Frying Pan Shoals slightly lower on winds and gusts, but up to 27' waves.

Quick moment of levity; I hope you enjoy:

My two terriers just killed a skunk in the back yard. My neighbor down the road saw the lights on and called to ask if had shot one. That bad.

Hope all do well with the storm! If you are hunkered down in a small space, please think of the company I am keeping in my basement and smile a little. We can't go into the rest of the house either.

All take care!



I hear fabric softener works on the smell, but I've never tried it. I keep a gallon of industrial enzyme skunk deodorizer on hand for this kind of occasion.
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1458. GatorWX
Probably one of the ugliest 950mb storms I've seen.
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Quoting tiggeriffic:
ok...last one for tonight...Battery again...look at the water line on the right...then the road on the left...you can see it is higher...and it wasnt more than 10" down from where my son was standing on the top of the wall where the guardrail is


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1456. MahFL
The center of Irene is now shaped like an S.
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1455. Levi32
Quoting 900MB:


Do you think they nailed the center on that pass?


Yeah it looks like it. It's hard to miss the center of a hurricane with the plane. They almost always get it on the first pass.
Member Since: November 24, 2005 Posts: 635 Comments: 26652
1454. GatorWX
Quoting Levi32:
Extrapolated pressure still near 950-951mb:

023500 3231N 07655W 6969 02721 9506 +156 +125 339020 021 010 001 03


Impressive, considering her sat presentation.
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ok...last one for tonight...Battery again...look at the water line on the right...then the road on the left...you can see it is higher...and it wasnt more than 10" down from where my son was standing on the top of the wall where the guardrail is
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Despite the weakening, I hope New Englanders are still taking her seriously.
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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.