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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1852. JGreco
Quoting MississippiWx:
150...



Wow...wonder if that lines up with the beginning of the weakening Texas ridge that is suppose to start at the beginning of September.:O...??
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Quoting MississippiWx:
141...Jose and....KATIA <<<<


Oh man, not again... here they come
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1850. Verdog
Dumb question.... Why does the HH's avoid Georgia like the plague? They fly south to reach a northern target. I could see this 12 hours+ ago.....

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And just for fun, a list of rivers in eastern PA, NJ and southeastern NY that are at record highs for the date now.

Schuykill River (PA)
Lehigh River (PA)
Hackensack River (NY, NJ)
Passaic River (NJ)
Delaware River (NY)
Nissequogue River (NY)
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162

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Quoting P451:


hah!

Thanks. Very well prepared. Am likely to lose power possibly for days where I am....so don't think I croaked if I'm not around for a spell after tomorrow LOL


I just want you to know that all of us Floridians have not stopped watching and hoping and praying that others in the path of Irene have as little damage as possible. Unfortunately I think we still have a "knee jerk reaction" when a tropical system appears to head our way...every western wobble equates to blue tarps, no electricity, massive debris, closed stores, no gas, curfews, etc. I'm sorry you've gotten the impression that once we are out.of danger, no one else matters. We, well I can speak for myself and others from FL that openly blog and support others, haven't stopped watching, waiting, and sending our best to those in any strong system's path! 2004-2005 has left a lasting scar that we wish no one else must endure, which its why my prayers and contributions have gone out to PR, DR, the Bahamas, and anywhere else forced to suffer the wrath of Irene and/or any other catastrophe our American and Island bretheren have had and will have to endure. Please be safe and know that you are in many thoughts and prayers!!!! Keep us up to date, please!! Mel
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Quoting Seastep:


She is strengthening as I type.


Also, delete all your posted blogs, please...
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New tornado watch just issued for NE-ern NC, SE-ern VA and extreme S-ern MD until 11AM eastern.
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I don't know about anyone else, but I am seeing a couple of things tonight:

1. Irene has resumed a motion that will reconnect with the forecast track, if it holds.

2. Irene appears to be strengthening as she begins passing over the Gulf Stream. I think the weakening trend of the last 18 hours or so is over, and Irene may maintain Cat 2 status until she reaches Long Island. JMO's.
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1843. Zaphod
Is there a total kept for sondes dropped and recon flights? This storm has to have set records, probably 2x any other cane, for measurement effort.

Still, it's a weird storm. For two days I keep thinking she's about ready to build again, and then she falls apart. Yet another modest strengthening cycle seems to be commencing.

We shall see what the night brings....
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Quoting hswiseman:
Outflow to the south has improved MARKEDLY. Irene has not looked this well since yesterday morning. Overall angular momentum is huge, obviously, and if symmetry can be regained, it looks possible to add intensity.

Link
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VIRGINIA BEACH – A 22-year old man has drowned while surfing in the Croatan area.

On Thursday evening, Lee Terrell of Norfolk was surging in waist deep water about 50 yards off shore. His friends say he paddled past two waves but suddenly began to struggle in the water.

Two of Terrell’s friends and a bystander went into the water and pulled him to shore. A nurse and another person started CPR until rescue personnel arrived. Terrell was taken to Virginia Beach General Hospital but was pronounced dead at 7:23.

The emergency call came in at 6:19 p.m. and happened in the 900 block of South Atlantic Avenue.



Unfortunately, we already have a death associated with the hurricane here in VB, but waves were relatively small today. I think this might be due to inexperience in the water or a medical condition possibly. Sorry to see this.
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1838. JLPR2
Quoting MississippiWx:
150...



Very different to the last run. This time it strengthens the first wave and turns it into Jose while the second one stays weaker and becomes Katia. It was backwards in the 18z run.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
1837. bassis
Link

Cool pic. Lets you see the true size of her
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Quoting Floodman:


Uh oh...press finally got him a FEMA guy
LMAO You ain't right!
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1834. docrod
Quoting Seastep:


She is strengthening as I type.


Stop typing please ;>)
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Quoting ShenValleyFlyFish:
I'm over the Mountain. Hop we get some rain out of this, it's in no way assured. Hope everyone else stays safe. Got a Brother down in the lowlands, but he's a survivor and no fool. He's on the short wave post event crew so if anything really happens he'll be in the thick of things and loving every minute.


Okay, good news.
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150...

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1831. Seastep
Quoting galvestonhurricane:
I don't see Irene strengthening before landfall. Although instead of weakening, she may stay at the same intensity.


She is strengthening as I type.
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Quoting NoVaForecaster:


Interesting looking swirl near the Canary Islands.



Looks like an upper level disturbance.
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1828. hamla
one model shows a ts in gom in a week or so,is this still showing up on latest model runs???
i saw this on a post earlier
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Quoting MississippiWx:


Could be part of the reason why the Atlantic instability is going back up, coupled with climatology. However, I believe the lack of instability in the Atlantic has been more global-related than SAL related.



It appears that we are in for a long September...
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Quoting PrivateIdaho:


Shen, what conditions are you expecting at your location?
I'm over the Mountain. Hope we get some rain out of this, it's in no way assured. Hope everyone else stays safe. Got a Brother down in the lowlands, but he's a survivor and no fool. He's on the short wave post event crew so if anything really happens he'll be in the thick of things and loving every minute.
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141...Jose and....KATIA <<<<
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By the way, to all the people who incorrectly said that Irene would be the next Ike, I am glad (for the sake of North Carolina) that I was right.
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Quoting GTcooliebai:
Yep just as I feared, SAL is non-existent:



Could be part of the reason why the Atlantic instability is going back up, coupled with climatology. However, I believe the lack of instability in the Atlantic has been more global-related than SAL related.

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Quoting Losttsol:
Light, but steady rain now here in Virginia Beach. Wind not bad though. Maybe some 20mph gusts. The fun begins.


Stay safe, my fellow Virginian :-)

Thoughts and prayers your way.
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1821. Dennis8
Wilmington rain from Irene Precipitation 3.75 in
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1820. jonelu
Quoting PrivateIdaho:
Impressive rain sheild....tornado warnings popping up.

They are getting hammered pretty well. And her slow forward motion does not bode well for anyone in her path..
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Link
Quoting hunkerdown:
anybody got a satellite of Africa to see what this new "potential system" originates from ?
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I don't see Irene strengthening before landfall. Although instead of weakening, she may stay at the same intensity.
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Video of Hurricane Irene 1999 - upper TS to Lower Cat 1 winds sustained with gusts to 80 mph. Sounds like some people will be sitting thru this for 8 to 10 hours from NC northward.

Link
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Quoting NoVaForecaster:


Interesting looking swirl near the Canary Islands.



Most likely more upper level in nature.
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Yep just as I feared, SAL is non-existent:

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Watch during the hurricane season and post when I see fit. Appreciate all here. It just sometimes seems like the blog is too caught up in drama to remember why we're here, the incredible phenomenon of the tropics.

Do what they say - and if you like you can even Ignore the user...
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ROFL -
Flood you always do make me laugh! : )
Quoting Floodman:


Uh oh...press finally got him a FEMA guy
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129...Strengthening Jose and TD12?

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1810. Thrawst
I don't know if this has been mentioned yet.. but is it ironic that TD-10 in 2005 ALSO dissipated.. and was 1/2 responsible for the formation of the K word? :/
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Quoting ProgressivePulse:




Thank you very much :)
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Outflow to the south has improved MARKEDLY. Irene has not looked this well since yesterday morning. Overall angular momentum is huge, obviously, and if symmetry can be regained, it looks possible to add intensity.
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1807. snotly
1724 total US tornadoes this year so far. How many will Irene add?
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Recipe for de-skunking a dog:

Need:

1 quart (or liter) of 3% Hydrogen Peroxide, H2O2.
Use fresh (unopened) hydrogen peroxide (H2O2). Hydrogen peroxide eventually turns into water (H2O).
1/4 cup (50 ml.) of Baking Soda
1 teaspoon (5 ml.) of Liquid Soap
1 pair of plastic or latex gloves

Method:

Combine the ingredients in an open container (do not store in a sealed bottle--it will explode).

Using gloves, wash your dog with lukewarm water and the mixture while the mixture is bubbling. Work the mixture well into the fur.

Be sure to concentrate on the area that was sprayed.
Keep mixture away from your dog's face and eyes (it's a harsh solution).

Let the mixture stand for 10 minutes or so before rinsing off.

Rinse the dog with lukewarm tap water. Don't wash the mixture into your dog's eyes (use a washcloth to cover the eyes if you're rinsing the head).

How it works:

Forget what you have heard about tomato juice--it doesn't work. Skunk spray is mainly composed of low molecular weight thiol compounds. ("Thiols" are compounds with the "-SH radical" attached to a carbon atom.)

In industrial applications, alkaline hydrogen peroxide (H2O2) is used for scrubbing similar compounds from waste gas streams.

Hydrogen peroxide and baking soda, when combined, become a "chemical engine" for churning out oxygen. That's why it has to be used immediately after mixing. The soap breaks up the oils in the skunk spray, allowing the other ingredients to do their work.

------------------------------------------------

This is the method groomers use. Good luck!

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Recon heading back for another look.

Flying over Tallahassee...


Link
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Quoting MississippiWx:
105..Jose, with another strong wave behind him. By the way, the Euro developed this same wave on the 12z run.



The tropics are going to heat up after Irene...
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Quoting MississippiWx:
105..Jose, with another strong wave behind him. By the way, the Euro developed this same wave on the 12z run.

No surprise here, the SAL must be good now that Irene paved the way. Plus we're in peak season now.
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Quoting BaltimoreBrian:


Of course tides on the NC coast are above normal now. I never said they wouldn't be.

In NY and NJ there have been several noreasters that brought high tide surges without necessitating the evac of hundreds of thousands of people.

In April 2007 all NYC tidal guages were above 4.5 feet above normal, with some greater than 6 feet above normal with a pressure of 28.60" at JFK airport and over 7" of rain in Central Park. No mass evacuations.

In Dec 1992 storm surge at NYC stations was higher. 5 to 7 feet.

And Hurricane Donna brought a surge of 11 feet to Battery Park in 1960. Hundreds of thousands lived in today's evacuation zones then. They didn't die.

I think the threat from the storm surge in the NYC area is being overhyped.

And I think the threat from river flooding inland is underhyped.
You obviously know more than I. I will agree on the river flooding. That I know something about.
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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.