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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2002. Levi32
950.9mb extrapolated:

055730 3324N 07634W 6967 02715 9509 150 070 131009 012 009 003 03

She's still holding steady, amazingly.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
2001. JRRP


here we go again
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Quoting Levi32:


These are a lot weaker than even earlier today, though, which is good news. However, it is the very weakest quadrant of the storm. We'll see if they are weaker elsewhere as well. We're about to get a pressure reading in the eye.


Hopefully every quadrant is weaker.
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1999. JLPR2
ECMWF is running.
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1998. Levi32
Quoting VAbeachhurricanes:


yeah, winds have not been very impressive from the start today levi.


These are a lot weaker than even earlier today, though, which is good news. However, it is the very weakest quadrant of the storm. We'll see if they are weaker elsewhere as well. We're about to get a pressure reading in the eye.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting Levi32:
Very lackluster winds in the SW quad of Irene on this new pass from the hurricane hunters.



LOL. We posted the same exact thing....and I swear I did not see you post it before I did.
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Quoting atmosweather:
Wow...RECON plane almost at the center coming through from the SE side and there are almost no hurricane force winds at flight level let alone the surface. Her southern portion is just very very weak compared to the northern and eastern sides.


Very dry in the South West.

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Quoting Levi32:
Very lackluster winds in the SW quad of Irene on this new pass from the hurricane hunters.



yeah, winds have not been very impressive from the start today levi.
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Quoting AllStar17:
Where is my new avatar? I uploaded it like 25 minutes ago now.


Did u try CTRL-F5
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It appears that Irene's southwestern quadarant lacks any hurricane force winds.
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Great website Tampa
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Quoting Levi32:
Very lackluster winds in the SW quad of Irene on this new pass from the hurricane hunters.



Good!
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Wow...RECON plane almost at the center coming through from the SW side and there are almost no hurricane force winds at flight level let alone the surface. Her southern portion is just very very weak compared to the northern and eastern sides.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting jonelu:
Im still here...never left.


Hear you jonelu, I'm still here too, not leaving....just trying to make the point that all Floridians aren't self-contained and heartless, glad to know you're one if us that still care about others that have to experience potential devastation! You seem very supportive....Mel
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1986. Levi32
Very lackluster winds in the SW quad of Irene on this new pass from the hurricane hunters.

Member Since: November 24, 2005 Posts: 635 Comments: 26547
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Well, from the looks of things we get more severe weather some days in WCF than Irene is dishing out. 5+" just the other day (in 90 minutes!). Last summer a 50mph gust took an oak tree down. Those seabreeze storms can get pretty crazy. Of course, about 1-2 hours and the sun is out again, this is agonizingly slow for folks it seems. Nice east jog, now just needs to pick up some forward speed.
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Night all....be safe everyone in Irene path...

Check back in tomorrow.
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Quoting NJ2S:
does it look as if she will go west or east of NYC? any ideas?


More likely to pass just to the east rather than to the west. But it won't matter a great deal considering Irene's massive windfield and storm surge and her potential to dump 6-10 inches of rain over a pretty wide area in the mid-Atlantic and Northeast.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting AllStar17:
Where is my new avatar? I uploaded it like 25 minutes ago now.


It's dead.
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Quoting TampaSpin:


Didn't know this was you and Orca's Blog........Of course many know that....
Why person in question got where he is. Got confused as to who's blog it was. And No it isn't mine, but I do know who's it is and try to act accordingly. Nuff said.
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Where is my new avatar? I uploaded it like 25 minutes ago now.
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Quoting c150flyer:
Power just went out here in more head city...



Large band moving onshore now, highest winds yet for you.
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Quoting NJ2S:
does it look as if she will go west or east of NYC? any ideas?


Right now I'd say east.
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Quoting Ryuujin:
why are people thinking this is going to go out to sea? I mean, it's following the path almost to a T. *sigh* people.


As a MA resident, I'd LOVE for Irene to magically curve out to sea. Not even REMOTELY counting on it.

Seems like a whole lot of wishful thinking to say she's definitely going out, though, given the evidence at hand.
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Quoting 72andSunny:
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!



Fantastic. Thank you!
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1974. NJ2S
does it look as if she will go west or east of NYC? any ideas?
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Quoting tvengineer8:



If the flood wall near my house in New Orleans had been built 1/2 as well as that pier was... my life would be totally different right now :-)
Second one. Been owned by the same family for years. I googled it. interesting.
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Quoting ShenValleyFlyFish:
Perfectly appropriate. As long as you were going to play by the rules I was going to let it slide. When you guys started sucking in innocents something needed to be said.


Didn't know this was you and Orca's Blog........Of course many know that....
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Power just went out here in more head city...
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Daggers!
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1968. whitewabit (Mod)
Selected buoys wave height ...

41001 - 20.7
41004 - 17.4
41013 - 20.7
41036 - 26.6
44014 - 11.2
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1967. Ryuujin
Quoting SamWells:


Impressive, but offshore waves ain't inshore surge, right?


it's not, of course. But it's an indication of the danger of the surge.
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Quoting QacarXan:
Pier at Topsail still taking sledgehammer waves again and again. That pier is well-designed to last so long:

http://www.surfchex.com/index.php



If the flood wall near my house in New Orleans had been built 1/2 as well as that pier was... my life would be totally different right now :-)
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Quoting Ryuujin:


Did you hear the offshore wave heights? 22 feet every 15 seconds? That's crazy. That's just nuts sort of surge coming towards the coast.


Impressive, but offshore waves ain't inshore surge, right?
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1964. Ryuujin
why are people thinking this is going to go out to sea? I mean, it's following the path almost to a T. *sigh* people.
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Quoting TampaSpin:



This was not necessary....
Perfectly appropriate. As long as you were going to play by the rules I was going to let it slide. When you guys started sucking in innocents something needed to be said.
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Quoting thegoldenstrand:
Hope anyone near Pamlico Sound NC has evacuated, it looks like it will get pretty dicy there within the next 7-9 hours. Does crossing any of those outer banks really count as a landfall? Thinking max sustained winds should be around 95-100 mph.


Yes it would count as a landfall.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting Levi32:


I apologize...just thought a live look at Irene was worth seeing. That was my only intention.
Knew that. Why I said something. Figured if folks who knew history collected a stint in the brig they had it coming but saw some other folks getting sucked in.
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Hope anyone near Pamlico Sound NC has evacuated, it looks like it will get pretty dicy there within the next 7-9 hours. Does crossing any of those outer banks really count as a landfall? Thinking max sustained winds should be around 95-100 mph.
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AF306 Mission 31 will reach the center shortly.
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Cape Lookout reporting winds out of the East at 51 mph gusting to 59 mph.

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Quoting Orcasystems:


He is a guy who was permanently banned from WU by Dr Masters... but some people like to rub Jeff's face in it by intentionally posting information about it.



This was not necessary....
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Pier at Topsail still taking sledgehammer waves again and again. That pier is well-designed to last so long:

http://www.surfchex.com/index.php
Member Since: August 25, 2011 Posts: 0 Comments: 20
Quoting ProgressivePulse:
T-minus 15 minutes, next band moving onshore, further increased winds.





That next rainband is probably going to hammer the Onslow Bay, Morehead City and the southern OBX with hurricane force gusts.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
1954. KEEPEROFTHEGATE (Mod)
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T-minus 15 minutes, next band moving onshore, further increased winds.



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1952. KEEPEROFTHEGATE (Mod)
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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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