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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Dang, step away for an hour. Irene trying her darndest to get fully dressed again :(
Member Since: Posts: Comments:
1151. Remek
Quoting tiggeriffic:


OK...i gotta see this...where's the link


Topsail cam link:

cam
Member Since: August 29, 2005 Posts: 0 Comments: 118
Quoting TropicalAnalystwx13:


Great...


The fun has not even started!
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1149. hahaguy
Topsail is getting hammered.
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Note: Not here, but in Topsail Island.
Member Since: July 6, 2010 Posts: 113 Comments: 32860
1147. 996tt
Quoting PensacolaBuoy:


Weather Channel forecast.
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Quoting Remek:


It's deceiving - when the camera zooms in the shadow is projected on the breaking waves, makes it looks like a section is floating.


Saw it again, you are exactly right.
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1145. Levi32
Quoting atmosweather:


Surge in this area is expected to be 3 to 6 feet, with the possibility of higher amounts depending on the exact track of Irene. This is a very dangerous amount of water rise and could really put parts of the coastal island underwater. They better be very prepared and confident that their structure can hold under 70-80 mph winds and a Category 3 type storm surge.


Agreed.
Member Since: November 24, 2005 Posts: 635 Comments: 26701
Quoting PensacolaBuoy:


IM IM THAT BOAT :D
Member Since: July 27, 2008 Posts: 0 Comments: 108
1143. zawxdsk
Quoting Dennis8:

Wilmington

9:45 PM 75.2 °F - 71.6 °F 89% 29.41 in 4.0 mi NNE 26.5 mph 46.0 mph 0.31 in Rain Rain


RAP's Surface Page shows 25kts up and down the coast with gusts in the upper 35-39 kt range. Lots of heavy rain.
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1142. Dennis8
Quoting PensacolaBuoy:


YIKES!
Member Since: August 15, 2008 Posts: 0 Comments: 446
1141. Dennis8
Quoting zoomiami:


With the water like that already -- hate to see it as the storm gets closer.


Just like Ike.. we woke up Friday morning 6am with water topping Galveston seawall and the eye was 18 hours away...2:10 am Saturday!
Member Since: August 15, 2008 Posts: 0 Comments: 446
Quoting PensacolaBuoy:



Is that from today? :}
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Quoting PensacolaBuoy:

doom
Member Since: July 7, 2010 Posts: 0 Comments: 5725
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1137. Dennis8
Hatteras-first gust above 40 mph


9:47 PM 78.8 °F - 75.2 °F 89% 29.65 in 1.8 mi ESE 26.5 mph 40.3 mph 0.23 in Rain Heavy Rain
Member Since: August 15, 2008 Posts: 0 Comments: 446
Quoting Levi32:


That's amazing. The water is pushing out very far ahead of the center.


With the water like that already -- hate to see it as the storm gets closer.
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Quoting Levi32:


That's amazing. The water is pushing out very far ahead of the center.


Reminiscent of Ike...this storm reminds me of Ike with similar size and strength...
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1134. 996tt
Quoting jdjnola:


Oh. Wouldn't know about that, nothing is that fancy in Southern Louisiana. Haha!


Yep, Ike busted the end of Pensacola Pier up and that pier is long and perhaps 25 to 30 feet off the water.
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Quoting cindyker:


Its mesmerizing... those are big waves...
Yup. I've also got a Nags head cam up, but it's a ton calmer. I've never been down there before, though, so I'm not familiar with area. Don't know if Nags is more protected...

cam
Member Since: August 28, 2005 Posts: 0 Comments: 153
1132. SQUAWK
Quoting PcolaDan:


Ah I see, a tropical delusion. :|

That's it exactly. Clearly.
TIA
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What's ironic about the complaints I've seen in these forums about the precautionary actions being taken in NYC is.... most of them probably don't even live in NYC, or the Northeast for that matter! A few of my friends in Manhattan have told me most of the people there aren't too upset about the evacuation orders and transit being shut down. It's an excuse to miss work and go party somewhere out of the evacuation zone, to most of them.
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1130. Remek
Quoting PcolaDan:
You guys must be looking at a different cam, I still see the pier, and with lights blazing.


It's deceiving - when the camera zooms in the shadow is projected on the breaking waves, makes it looks like a section is floating.
Member Since: August 29, 2005 Posts: 0 Comments: 118
Quoting Methurricanes:
Wait, did or did not the Topsail Beach Peir collaspe?


OK...i gotta see this...where's the link
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Quoting Methurricanes:
Wait, did or did not the Topsail Beach Peir collaspe?


No, it did not...Yet.
Member Since: July 6, 2010 Posts: 113 Comments: 32860
Quoting dogsgomoo:
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.


Surge in this area is expected to be 3 to 6 feet, with the possibility of higher amounts depending on the exact track of Irene. This is a very dangerous amount of water rise and could really put parts of the coastal island underwater. They better be very prepared and confident that their structure can hold under 70-80 mph winds and a Category 3 type storm surge.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
I can't tell if Topsail pier pics are repeating...

you can see the deck of the pier moving up and down and side to side - not the best thing for structural integrity/longevity
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Quoting SQUAWK:


It was an illusion caused by the cam zooming in on a big wave that overtopped the pier and then the cam panned to the left and it looked like the thing collapsed -- but it did not.


Ah I see, a tropical delusion. :|
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Quoting Methurricanes:
Wait, did or did not the Topsail Beach Peir collaspe?

Nope still there:
Cam Link
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1123. Dennis8

Wilmington

9:45 PM 75.2 °F - 71.6 °F 89% 29.41 in 4.0 mi NNE 26.5 mph 46.0 mph 0.31 in Rain Rain
Member Since: August 15, 2008 Posts: 0 Comments: 446
1122. jdjnola
Quoting PcolaDan:


The newer ones here are made so the boards break free and save the main structure. Easy to just puts boards back down.


Oh. Wouldn't know about that, nothing is that fancy in Southern Louisiana. Haha!
Member Since: August 4, 2008 Posts: 0 Comments: 238
Wait, did or did not the Topsail Beach Peir collaspe?
Member Since: August 1, 2011 Posts: 0 Comments: 701
Quoting ShenValleyFlyFish:
Switched cams I think. lol Look at direction of wave travel.


It looked to me that it was zoomed in on the end of the pier. But i am positive i saw it take it out. At least i think LOL
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Quoting cloudburst2011:
CALM DOWN
with your posts
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Quoting CybrTeddy:


What would you say the max winds are at your house right now?


Still not surpassed 55-60 MPH gusts, but they have been steadily increasing.

Quoting hurricanejunky:


Where are you located?


Eastern Pender County (The county north of Wilmington).
Member Since: July 6, 2010 Posts: 113 Comments: 32860
1117. SQUAWK
Quoting PcolaDan:
You guys must be looking at a different cam, I still see the pier, and with lights blazing.


It was an illusion caused by the cam zooming in on a big wave that overtopped the pier and then the cam panned to the left and it looked like the thing collapsed -- but it did not.
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1115. Levi32
Quoting ncstorm:


Yes thats from today..


That's amazing. The water is pushing out very far ahead of the center.
Member Since: November 24, 2005 Posts: 635 Comments: 26701
Quoting aspectre:
31.2n77.5w has been re-evaluated&altered for H.Irene's_12amGMT_ATCF
31.1n77.5w, 32.1n77.2w are now the most recent positions
Starting 26August_12amGMT and ending 27August_12amGMT

The 4 shorter line-segments represent HurricaneIrene's path
and the westernmost line-segment is the straightline projection.

Using straightline projection of the travel-speed&heading derived from the ATCF coordinates spanning the 6hours between 6pmGMT then 12amGMT :
H.Irene's travel-speed was 11.8mph(19k/h) on a heading of 14.3degrees(NNW)
H.Irene was headed toward passage over Atlantic,NorthCarolina ~15hours from now
(MRH is Beufort-MoreheadCity)

Copy&paste 27.7n77.3w-28.8n77.3w, 28.8n77.3w-30.0n77.4w, 30.0n77.4w-31.1n77.5w, 31.1n77.5w-32.1n77.2w, mrh, 12nc, 31.1n77.5w-34.89n76.327w into the GreatCircleMapper for more info

The previous mapping (for 26August_6pmGMT)

I think you mean NNE :P
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting bingcrosby:
Topsail pier just imploded

If I was the guy who built that pier I'd be watching that webcam too....
Member Since: September 23, 2008 Posts: 0 Comments: 22
Quoting padirescu:


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.
Those people all have a place to go and public transportation to get them there. You're advocating 5 million people leaving the city, with public transportation ceasing at noon, when many of them have nowhere to go - and, basing that on a hypothetical that there will be hundreds or thousands of deaths in high-rises caused not by the storm, but by secondary emergencies for which the authorities will not be able to respond.

I have no opinion whether areas of NYC should be evacuated. I do have an opinion about people assuming there is no risk in an evacuation.
Member Since: August 22, 2007 Posts: 0 Comments: 376
Quoting jdjnola:


For now! Those are some major waves!


The newer ones here are made so the boards break free and save the main structure. Easy to just puts boards back down.
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Personally I feel that they will retire this storm no matter what for at least political reasons. Knowing how backwards our economy is in every way.... the DOW would probably fall every day that a storm named Irene existed after this... more because of the area it is going to effect than anything. I know that sounds dumb... but just think about how things work now a days. So much as a bad memory can be economically damaging, and I think Irene is going to be a bad memory for many in the Mid Atlantic and Northeast, even if it only strikes as a tropical storm... or for that matter even if it doesn't make landfall at all. I guarantee you they will be politically pressured to retire the name.

But I have a feeling it's going to have more reasons than just political to be retired.
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Quoting TropicalAnalystwx13:
Maybe I shouldn't say I LOST power, but it was a long flicker ;)


Where are you located?
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As far as the high-rise buildings in Manhattan go....I'd expect some, many windows, to be blown out. Anyone in those apartments, condos, whatever, will be ok as long as they have some safe area away from flying glass. But the building itself should have structural integrity.
.
.
I'm more concerned that we'll see a whole building failure in some of the older lower-rise buildings that are built on soil of dubious integrity. There's many older 20-40 story brick "projects", ....and I'm afraid we may lose one or more. Just one would be a catastrophe, they have 2000-3000 people inside.
Member Since: August 3, 2005 Posts: 10 Comments: 5689
1107. 996tt
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


Structural engineer talking rationally about high rises now. Basically saying no cause for alarm. Props to TWC for interviewing this engineer so a voice of reason.
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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.


Its mesmerizing... those are big waves...
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31.2n77.5w has been re-evaluated&altered for H.Irene's_12amGMT_ATCF
31.1n77.5w, 32.1n77.2w are now the most recent positions
Starting 26August_12amGMT and ending 27August_12amGMT

The 4 shorter line-segments represent HurricaneIrene's path
and the northernmost line-segment is the straightline projection.

Using straightline projection of the travel-speed&heading derived from the ATCF coordinates spanning the 6hours between 6pmGMT then 12amGMT :
H.Irene's travel-speed was 11.8mph(19k/h) on a heading of 14.3degrees(NNE)
H.Irene was headed toward passage over Atlantic,NorthCarolina ~15hours from now
(MRH is Beufort-MoreheadCity)

Copy&paste 27.7n77.3w-28.8n77.3w, 28.8n77.3w-30.0n77.4w, 30.0n77.4w-31.1n77.5w, 31.1n77.5w-32.1n77.2w, mrh, 12nc, 31.1n77.5w-34.89n76.327w into the GreatCircleMapper for more info

The previous mapping (for 26August_6pmGMT)
Member Since: Posts: Comments:
Quoting ShenValleyFlyFish:
Sounds like time for a sick day to me.


A lot of people who work in NYC live upstate or out of the city. But if it were me, I'd be taking a sick day!
Member Since: August 22, 2009 Posts: 0 Comments: 3167
1103. owntime
Quoting Remek:


Thx for the link. Not sure how long that pier's going to last. It's really getting battered.


From the looks of the live cam, it appears that the pier will not make it.
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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: July 8, 2005 Posts: 259 Comments: 24579

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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.

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