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 TropicalAnalystwx13:
The pier is safe!


What would you say the max winds are at your house right now?
Member Since: Posts: Comments:
1101. hahaguy
1:43 AM GMT on August 27, 2011
Quoting TropicalAnalystwx13:
Maybe I shouldn't say I LOST power, but it was a long flicker ;)


If I were you I'd log off cause you don't want to risk damaging your computer when the power goes out for good.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
1100. ShenValleyFlyFish
1:42 AM GMT on August 27, 2011
Quoting aislinnpaps:


Yes, shutting it down and sending the workers home. One of them lives upstate and isn't happy. He won't be able to 'go home'. He lives about two hours upstate.
Sounds like time for a sick day to me.
Member Since: September 9, 2007 Posts: 36 Comments: 4687
1099. ncstorm
1:42 AM GMT on August 27, 2011
Quoting Levi32:


Is that a picture from today? Is there already flooding?


Yes thats from today..
Member Since: August 19, 2006 Posts: 13 Comments: 16225
1098. jdjnola
1:42 AM GMT on August 27, 2011
Quoting TropicalAnalystwx13:
The pier is safe!


For now! Those are some major waves!
Member Since: August 4, 2008 Posts: 0 Comments: 238
1097. weatherwart
1:42 AM GMT on August 27, 2011
Quoting chicagowatcher:

I'm still seeing it. The cam looks like it's programmed to zoom in, out and pan around. Depending on the cam action, you can lose the pier. But then again, maybe I'm seeing old content...


No, you're right. It's switching around to different angles. The pier is still there. But, it's taking a real beating.
Member Since: August 18, 2008 Posts: 0 Comments: 884
1096. RitaEvac
1:42 AM GMT on August 27, 2011
Quoting 900MB:


Hey, anywhere you go, there are dopes. Dopes in my hometown of NYC, dopes having hurricane parties on the beach in Virginia. For us Manhattan folks, we know a good storm and we know that these cheap assed glass towers pop 200lb glass sheets like nothing.


And they WILL
Member Since: July 14, 2008 Posts: 2 Comments: 9686
1095. dogsgomoo
1:42 AM GMT on August 27, 2011
This is a question for anyone that might be able to give a reasonable opinion.

I have some acquaintances living just a bit north of Seaside Heights New Jersey. I've visited them recently and even at regular tide the streets flooded so I've taken a look at the surge predictions for that area. They look high but these people say that they have seen those exact predictions before and all that happened was some decent winds, some street flooding, and the power went out. There will be a voluntary evac and curfew only. Once you're off the island you don't get back on. So they are staying. At least they are prepared with supplies for a week to ten days.

Now that Irene is weaker do you think that this is a reasonable decision on their part? I'm worried but it's hard for me to understand how the surge is really going to go.
Member Since: March 4, 2008 Posts: 0 Comments: 316
1094. JamesSA
1:42 AM GMT on August 27, 2011
Quoting victoriahurricane:
Hey Levi or atmos I heard on the TWC that this year the storm surge values given are what is expected on top of the land, is this true? a 3 foot surge wouldn't be pretty then.


If you think that through it really would make no sense. Ground is typically uneven and might be 8 feet higher in your back yard than in your front yard, or the yard across the street. Ground has hills and gullies and high spots and low spots over even a small area.

Storm surge has to be measured against some reliable constant in order to be meaningful.
Member Since: August 17, 2009 Posts: 0 Comments: 579
1093. AllStar17
1:42 AM GMT on August 27, 2011
Quoting TropicalAnalystwx13:
Maybe I shouldn't say I LOST power, but it was a long flicker ;)


Oh.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
1092. PcolaDan
1:42 AM GMT on August 27, 2011
You guys must be looking at a different cam, I still see the pier, and with lights blazing.
Member Since: August 22, 2008 Posts: 12 Comments: 6010
1091. TropicalAnalystwx13
1:41 AM GMT on August 27, 2011
Maybe I shouldn't say I LOST power, but it was a long flicker ;)
Member Since: July 6, 2010 Posts: 113 Comments: 32857
1090. Ameister12
1:41 AM GMT on August 27, 2011
TWCBreaking: NY Port Authority will close all 5 NYC Airports to all arriving flights beginning at noon Sat. They'll remain open for departing flights.

Via Twitter
Member Since: August 9, 2009 Posts: 10 Comments: 5085
1089. thewindman
1:41 AM GMT on August 27, 2011
video on surchex of Topsail Island pier is AMAZING
Member Since: August 21, 2008 Posts: 0 Comments: 143
1088. ncstorm
1:41 AM GMT on August 27, 2011
Quoting victoriahurricane:


How do you know that's from Irene? It's daytime there.



Star News
Member Since: August 19, 2006 Posts: 13 Comments: 16225
1087. weatherman566
1:41 AM GMT on August 27, 2011
Did you hear that someone already died off the Virginia coast? 22 year old surfer died while being caught in the rip currents from Irene.

Member Since: July 15, 2008 Posts: 0 Comments: 108
1086. TropicalAnalystwx13
1:41 AM GMT on August 27, 2011
Quoting Levi32:


Is that a picture from today? Is there already flooding?


Yes, major. It is not the only place.
Member Since: July 6, 2010 Posts: 113 Comments: 32857
1085. AstroHurricane001
1:41 AM GMT on August 27, 2011
Please repost the video link for Topsail Pier.
Member Since: August 30, 2008 Posts: 8 Comments: 2836
1084. rv1pop
1:41 AM GMT on August 27, 2011
Quoting NJcat3cane:
im sticking it out here in Atlantic City even with mandatory evac here..should be crazy

Darwin candidate.
Member Since: August 18, 2007 Posts: 0 Comments: 191
1083. WeatherNerdPR
1:40 AM GMT on August 27, 2011
Quoting Krycek1984:


doesn't get retired just because it caused 1.1 billion in damage.

Have you SEEN the aftermath in Eastern PR??
Member Since: July 7, 2010 Posts: 0 Comments: 5725
1082. chicagowatcher
1:40 AM GMT on August 27, 2011
Quoting Krycek1984:
the pier in that webcam from topsail island just collapsed. cool webcam!

I'm still seeing it. The cam looks like it's programmed to zoom in, out and pan around. Depending on the cam action, you can lose the pier. But then again, maybe I'm seeing old content...
Member Since: August 28, 2005 Posts: 0 Comments: 153
1081. AllStar17
1:40 AM GMT on August 27, 2011
Quoting TropicalAnalystwx13:


Well...for now, it is underwater, lol.


You lost power and it was already restored? Wow....talk about quick.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
1080. Levi32
1:40 AM GMT on August 27, 2011
Quoting ncstorm:
Carolina Beach



Is that a picture from today? Is there already flooding?
Member Since: November 24, 2005 Posts: 635 Comments: 26700
1079. ShenValleyFlyFish
1:40 AM GMT on August 27, 2011
Quoting want2lrn:
Pier just went POOF on that video
Switched cams I think. lol Look at direction of wave travel.
Member Since: September 9, 2007 Posts: 36 Comments: 4687
1078. victoriahurricane
1:40 AM GMT on August 27, 2011
Quoting ncstorm:
Carolina Beach



How do you know that's from Irene? It's daytime there.
Member Since: October 16, 2008 Posts: 0 Comments: 544
1077. TropicalAnalystwx13
1:40 AM GMT on August 27, 2011
The pier is safe!
Member Since: July 6, 2010 Posts: 113 Comments: 32857
1076. 900MB
1:40 AM GMT on August 27, 2011
Quoting RitaEvac:
NYC folks amaze me, they have no clue about wind in a tropical system. If the storm is only 70mph when it gets there they think ohhhhh, not a big deal people told ya, yeaaaaaaaaaaa, that's at the surface fool, go up hundreds of feet on up on those skyscrapers it'll be 100mph EASY. That's gonna be a lot of glass raining down, and don't even forget about the funneling affect on the city streets that are going to be stronger between bldgs than it will be on the coast.

Big time learning lesson on the way for the BIG APPLE


Hey, anywhere you go, there are dopes. Dopes in my hometown of NYC, dopes having hurricane parties on the beach in Virginia. For us Manhattan folks, we know a good storm and we know that these cheap assed glass towers pop 200lb glass sheets like nothing.
Member Since: June 11, 2006 Posts: 0 Comments: 684
1075. AstroHurricane001
1:39 AM GMT on August 27, 2011
Quoting chicagowatcher:
and a battery operated router...


Except that excessive recharging can reduce the overall power storage time capacity.
Member Since: August 30, 2008 Posts: 8 Comments: 2836
1074. bingcrosby
1:39 AM GMT on August 27, 2011
Topsail pier just imploded
Member Since: August 14, 2008 Posts: 0 Comments: 137
1073. EYEStoSEA
1:39 AM GMT on August 27, 2011
Dang, they get the power back on quick there in NC...when the power goes out here in MS, ya better get the generator going, cause it's gonna be hours and hours...
Member Since: September 16, 2010 Posts: 0 Comments: 1496
1072. TropicalAnalystwx13
1:39 AM GMT on August 27, 2011
Quoting victoriahurricane:


What's happening with your yard?


#1066.
Member Since: July 6, 2010 Posts: 113 Comments: 32857
1071. aislinnpaps
1:38 AM GMT on August 27, 2011
Quoting Methurricanes:
They are shutting down the MTA at 12:00pm tommorrow.


Yes, shutting it down and sending the workers home. One of them lives upstate and isn't happy. He won't be able to 'go home'. He lives about two hours upstate.
Member Since: August 22, 2009 Posts: 0 Comments: 3167
1070. Ameister12
1:38 AM GMT on August 27, 2011
Tornado warning for Hyde, Beaufort, and Pamlico County!

Member Since: August 9, 2009 Posts: 10 Comments: 5085
1069. PcolaDan
1:38 AM GMT on August 27, 2011
Quoting victoriahurricane:
Hey Levi or atmos I heard on the TWC that this year the storm surge values given are what is expected on top of the land, is this true? a 3 foot surge wouldn't be pretty then.


That doesn't make sense. At what height of land would it be? Sea level at the beach, 100 yards inland, a mile???
Member Since: August 22, 2008 Posts: 12 Comments: 6010
1068. Krycek1984
1:38 AM GMT on August 27, 2011
Quoting WeatherNerdPR:

Damage from Hurricane Irene has exceeded at least$1.1 billion USD.
I'd retire her.


doesn't get retired just because it caused 1.1 billion in damage.
Member Since: August 5, 2010 Posts: 0 Comments: 290
1067. victoriahurricane
1:38 AM GMT on August 27, 2011
Quoting TropicalAnalystwx13:
Sorry I was gone - lost power literally. Its back on now.


What's happening with your yard?
Member Since: October 16, 2008 Posts: 0 Comments: 544
1066. TropicalAnalystwx13
1:37 AM GMT on August 27, 2011
Quoting spayandneuter:


ahhh, no vague-posting! What kind of problems? Are you OK?


Well...for now, it is underwater, lol.
Member Since: July 6, 2010 Posts: 113 Comments: 32857
1065. emcf30
1:37 AM GMT on August 27, 2011
Member Since: August 7, 2010 Posts: 0 Comments: 1957
1064. ShenValleyFlyFish
1:37 AM GMT on August 27, 2011
Quoting chicagowatcher:
LOL i KNOW. I sat here staring at that for about 15 minutes just waiting for a huge swell to overtop it and knock all the lights out.

Impressive and scary.
It's what's underneath eroding will get it if it goes. They topple toward the waves usually.
Member Since: September 9, 2007 Posts: 36 Comments: 4687
1063. RitaEvac
1:37 AM GMT on August 27, 2011
Not sure of what the rule is, but for every 10 stories you go up, the wind increases 10mph, think about how many bldgs are 30-70 stories up in NYC, may I say glass damage....
Member Since: July 14, 2008 Posts: 2 Comments: 9686
1062. shadoclown45
1:37 AM GMT on August 27, 2011
Quoting Tazmanian:




any ch that Irene geting retired ?


Yes if the rains they predict will fall, fall we will have a retired storm from extensive damage anyways we're somewhere like 1.1 billion into this hurricane form puerto rico the Bahamas and evacuation costs.
Member Since: July 27, 2008 Posts: 0 Comments: 108
1061. Krycek1984
1:37 AM GMT on August 27, 2011
the pier in that webcam from topsail island just collapsed. cool webcam!
Member Since: August 5, 2010 Posts: 0 Comments: 290
1060. GeoffreyWPB
1:37 AM GMT on August 27, 2011
Did that pier just get taken out?
Member Since: September 10, 2007 Posts: 0 Comments: 11557
1059. WeatherNerdPR
1:37 AM GMT on August 27, 2011
Quoting Tazmanian:




any ch that Irene geting retired ?

Damage from Hurricane Irene has exceeded at least$1.1 billion USD.
I'd retire her.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
1058. SQUAWK
1:37 AM GMT on August 27, 2011
Quoting Dutchlady:


That's a sturdy pier, so far...


It just got wiped out!!!!
Member Since: December 9, 2008 Posts: 0 Comments: 2498
1057. want2lrn
1:37 AM GMT on August 27, 2011
Pier just went POOF on that video
Member Since: July 28, 2010 Posts: 0 Comments: 285
1056. summerland
1:37 AM GMT on August 27, 2011
Quoting TropicalAnalystwx13:
Sorry I was gone - lost power literally. Its back on now.

Be safe. And you can log off when you need to -- don't risk a power surge that damages your computer.
Member Since: August 30, 2008 Posts: 0 Comments: 85
1055. padirescu
1:36 AM GMT on August 27, 2011
Quoting DallasGumby:
But, what about the hundreds or thousands of deaths caused by 5 million people all trying to evacuate in a single day?


Seriously? You actually expect me to justify a response to this comment?

What's the average commute volume in and out of Manhattan each day and how many deaths are there on a daily basis? I'll leave it at that.
Member Since: September 2, 2008 Posts: 0 Comments: 62
1054. ncstorm
1:36 AM GMT on August 27, 2011
Member Since: August 19, 2006 Posts: 13 Comments: 16225
1053. TropicalAnalystwx13
1:36 AM GMT on August 27, 2011
Quoting Tazmanian:



you need a laptop


I have a laptop, lol, but it lost connection.
Member Since: July 6, 2010 Posts: 113 Comments: 32857
1052. weatherwart
1:36 AM GMT on August 27, 2011
Holy moley! That Topsail pier is getting creamed!
Member Since: August 18, 2008 Posts: 0 Comments: 884

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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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