Irene's eyewall collapses; further intensification unlikely

By: Dr. Jeff Masters , 3:14 PM GMT on August 26, 2011

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Satellite data and measurements from the Hurricane Hunters show that Irene is weakening. A 9:21 am EDT center fix by an Air Force Reserve aircraft found that Irene's eyewall had collapsed, and the central pressure had risen to 946 mb from a low of 942 mb this morning. The highest winds measured at their flight level of 10,000 feet were 125 mph, which would normally support classifying Irene as a Category 3 hurricane with 115 mph winds. However, these winds were not mixing down to the surface in the way we typically see with hurricanes, and the strongest surface winds seen by the aircraft with their SFMR instrument were just 90 mph in the storm's northeast eyewall. Assuming the aircraft missed sampling the strongest winds of the hurricane, it's a good guess that Irene is a mid-strength Category 2 hurricane with 100 mph winds. 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 wind shear of 10 - 20 knots due to upper-level winds out of the southwest. 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 Wlimington, North Carolina, shows that the outermost spiral bands from Irene are now beginning to come ashore along the South Carolina/North Carolina border. Winds at buoy 41004 100 miles offshore from Charleston, SC increased to 36 mph as of 10 am, with significant wave heights of 18 feet.


Figure 1. Distribution of Irene's wind field at 9:30 am 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 and storm surge potential for Irene
With its eyewall collapsed and just 24 more hours over water before landfall, it is unlikely Irene will 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 Category 2 hurricane at landfall in North Carolina on Saturday, and a rapidly weakening Category 1 hurricane at its second landfall in New England on Sunday. 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 9:30am EDT this morning, a wind analysis from NOAA/HRD (Figure 1) indicated that the potential storm surge damage from Irene rated a 5.1 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 gradually decline as Irene moves northwards and weakens, we can still expect a storm surge one full Saffir-Simpson Category higher than Irene's winds. 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. A surge rivaling that experienced during Hurricane Isabel in 2003 is likely in northern NC, southern Maryland, and up Chesapeake Bay on Saturday night. Coastal New England from New York City to Massachusetts may also see storm surges characteristic of a Category 1 hurricane during Sunday morning's high tide, even if Irene has weakened to a tropical storm. I continue to give a 20% chance that a storm surge high enough to over-top the Manhattan flood walls and swamp the New York City subway system will occur on Sunday.

Wind damage
I don't think Irene is going to do a lot of wind damage to the mid-Atlantic states, since the eye of the storm will be just offshore, and the I-95 corridor from Virginia to New Jersey will be on the weak (left) side of the hurricane. The current wind distribution of Irene (Figure 1) shows almost all of the hurricane's winds are on the right side of the storm, and by the time the storm reaches Virginia, there will be likely be no hurricane-force winds on the left side of Irene. Sustained winds should stay below 74 mph (hurricane force), and wind damage will be similar to that wrought be some of the strongest Nor'easters of the past 20 years, from Virginia northwards to New York City. Since Irene will be steadily weakening as it approaches its second landfall on Long Island, I give a 50% chance that no mainland U.S. surface station in New England will record sustained hurricane-force winds. I do think it likely that one or more of the offshore islands--Block Island, Nantucket, and Marthas Vinyard--will get Category 1 hurricane winds. Though the wind damage to buildings will be similar to what the Northeast has seen during some of the more severe nor'easters of the past 20 years, tree damage will be much worse. The trees are in full leaf during hurricane season, and catch the wind much more readily than during the winter. Tree damage will very heavy, and we can expect trees in regions with saturated soils will fall over in high winds onto power lines. Irene is likely to cause one of the top-five most widespread power outages in American history from a storm. The record power outage from a Northeast storm was probably the ten million people that lost power during the great Blizzard of 1993. I don't think Irene's power outages will be quite that extensive, but several million people will likely lose power.

Irene likely to bring destructive fresh water flooding
In addition to storm surge, flash flooding and river flooding from Irene's torrential rains are the main threats. The hurricane is expected to bring rains in excess of 8" to a 100-mile-wide swath from Eastern North Carolina northwards along the coast, through New York City. The danger of fresh water flooding is greatest in northern New Jersey, Southeast Pennsylvania, and Southeast New York, where the soils are saturated from heavy August rains that were among the heaviest on record. New Jersey has had its 6th wettest August on record, with most of that rain falling in the past two weeks. Expect major river flooding throughout New Jersey the Delmarva Peninsula, and regions near New York City, as Irene's rains run off the saturated soils directly into the rivers. In general, the heaviest rains will fall along the west side of the hurricane's track, and the greatest wind damage will occur on the east side. I don't think flooding from heavy rains will be a huge concern in North Carolina, which is under moderate to severe drought. Irene's rains are likely to do some good in Southeast Virginia, where a fire triggered by lightning from a thunderstorm on August 4 sparked a fire in the Dismal Swamp that is burning out of control. Right now, it does not appear that tornadoes will be a major concern, but there will probably be a few weak tornadoes. Hurricane Bob of 1991, the last hurricane to affect New England, spawned six tornadoes, most of them weak F-0 and F-1 twisters.


Figure 2. Predicted rainfall for the 5-day period ending at 8 am EDT Wednesday August 31, as issued by NOAA/HPC.

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 there, and I will be available if my schedule permits. Listeners can email in or call in questions. The email address to ask questions is broadcast@wunderground.com.

Portlight mobilizes for Irene
The Bahamas have been hit hard by Irene, and unfortunately, it appears that the Northeast U.S. may have its share of hurricane victims before Irene finally dissipates. My favorite disaster relief charity, Portlight.org, is mobilizing to help, and has sent out their relief trailer and crew to North Carolina. Check out this blog to see what they're up to; donations are always needed.

Jeff Masters

Hurricane Irene's Wrath ! (MikeTheiss)
A shot of the Palm Trees at Nassau, Bahamas being thrashed by high winds during Irene's closest approach !
Hurricane Irene's Wrath !
Aftremath of Hurricane Irene in Nassau, Bahamas (ktbahamas)
Utility pole with street light snapped in half by Irene's winds on a busy street in New Providence.
Aftremath of Hurricane Irene in Nassau, Bahamas
Irene Response (presslord)
Portlight deploying to North Carolina
Irene Response

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Quoting 69Viking:


No kidding, does the NHC not pay attention to their own information when deciding direction of a storm??? It's like they don't want to go against the forecast of their last advisory that said it would continue N for a while and then turn NE yet even a rookie weather enthusiast can see via satellite that it moved W of N over the last few hours, this wasn't just jog left of the eye.


Relax. .2 degrees is only about 15 miles.
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Quoting carcar1967:



I would tend to disagree, I think she will intensify a little before landfall. Only time will tell. I hope she does weaken.


She's a tired old bag of wind now definitately not the impressive storm of last night
Member Since: July 31, 2006 Posts: 19 Comments: 1557
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Member Since: July 15, 2006 Posts: 169 Comments: 53296
We are located on the West side of Morehead City. So far we are just seeing some light rain and a little breeze...expect that to change for soon...especially if that eye keeps heading towards us!

Does anyone know if Grandpa got off of Atlantic Beach? Has anyone heard from him in the past 24hrs? There was a mandatory evac of his area so hopefully he listened!
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what are everyones thoughts on TD10?
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ECMWF 12Z run is in...



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Quoting FLdewey:
Jet or not jet... I will be impressed if she's a hurricane when she gets to NYC.


Irene will not be a Hurricane when she blows into NY City and the media hype will scare everyone except New Yorkers
Member Since: July 31, 2006 Posts: 19 Comments: 1557
Quoting huber:


I agree! Looking at the visable this thing is headed toward Wilmington. Very intrested to see when the "turn" occurs. Wilmington, Wrightsville Beach, Surf City, Topsail Beaches could be in the landfall area.


No kidding, does the NHC not pay attention to their own information when deciding direction of a storm??? It's like they don't want to go against the forecast of their last advisory that said it would continue N for a while and then turn NE yet even a rookie weather enthusiast can see via satellite that it moved W of N over the last few hours, this wasn't just jog left of the eye.
Member Since: August 25, 2006 Posts: 1 Comments: 3010
Quoting FLdewey:
Jet or no jet... I will be impressed if she's a hurricane when she gets to NYC.


I agree, at the rate she is falling apart she may be a TS when she gets about even with Virginia.
Member Since: July 27, 2011 Posts: 0 Comments: 204
Quoting Cayman2010:

Whilst that is certainly the case for many of the said people, it is still a gross generalization and certainly not indicative of all. There are many people from those places listed who do not fall into this generalization and continue to follow the situation with great concern for all those in Irene's path.

They are also the ones who just aren't necessarily, being condescending and telling you what to do :-)


Many of us are lurkers with minimal posts. It doesn't mean we don't care.
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Quoting Melagoo:
I think Irene is weakening by the hour won't be the threat she was earlier but still a big storm Probably a weak Cat 1 at most - Media Hype at its best again



I would tend to disagree, I think she will intensify a little before landfall. Only time will tell. I hope she does weaken.
Member Since: June 9, 2011 Posts: 0 Comments: 100
Quoting duranta:
"Hindsight is much better than foresight. You can use the same argument about the people who died from the evacuation of parts of Houston in advance of Rita. In hindsight, Houston didn't need to be evacuated, yet people died from the evacuation.

I'm not being critical of those who make the evacuation/no evacuation call. I'm just saying the call has to be made with the best available information, not "pretending" a storm will be something it is not likely to be."

Houston did not have its act together as far as contr-flow. Louisiana had problems with it during Gustave evac despite many practice runs. People weren't allowed to get out of the flow, for example, for personal needs. At times, the human factor is not considered though you are moving masses of humanity.


The Houston Rita evacuation was unnecsessary and an over reaction by a politician. Only three areas of Houston needed to be evacuated, but Mayor Bill White ordered the evacuation of the whole city, declaring "Houston would not be another Katrina". He made his decision without consulting Texas state emergency management officials and called for the evacuation of Houston before Galveston was evacuated. The deaths that occured during the Houston evac are Bill White's responsibility.
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Quoting P451:


Airports will close. Raritan bay south of JFK is slated to get 90kt gusts sunday afternoon and 26 foot waves.

They'll shut down late Saturday or very very early Sunday and not reopen until Monday in a limited capacity - and that depends on what damage the airport sustains. It's pretty wide open to the water.

I can only imagine what's going to surface from those waters. Been a big "dumping ground" for decades.
Member Since: August 3, 2005 Posts: 10 Comments: 5526
Quoting CarolinaHurricanes87:
A few rain bands have come thru Wilmington but not much so far. Interested to see how high the surge at wrightsville is... I've heard 2-4 and 8-10 so idk what to believe. Stocked up and ready to go though, just waiting at this point.


Use the WunderMap Hurricane products and turn on the Storm Surge product for a quick overview.
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Folks in the Onslow Bay area beware!!This thing is really gonna push some water up in there! Wouldn't surprise me to see 10-15 ft. with the water she's pushing!
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Quoting sullivanweather:
Due to the dry stable air in the mid levels one can see the waves in the atmosphere emanating from Irene.

http://aviationweather.gov/adds/satellite/display Sat.php?region=ALB&isingle=mult_big&itype=vis



Thanks, sullivanweather. Thats a very interesting phenomenon you have pointed out. It shows, for example, that all of Massachusetts is already beginning to feel the influence of Irene!

Can you or someone please explain more about these waves? What are they and how are they propagated to such a long distance away from the core... They seem to be some sort of pressure wave, not carrying moisture or heat... Is that correct? It's extremely interesting to see how these waves move out so far from the core... to me at least!
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09L/MH/I/C2
RI FLAG (off)
RD FLAG (flag)
MARK
31.29n/77.08w





ALWAYS FOLLOW NHC/TPC FORECASTS FOR ALL WARNINGS REGARDING THIS STORM
Member Since: July 15, 2006 Posts: 169 Comments: 53296
657. Vero1
Quoting FLdewey:
Irene is really not looking that good.
nor was this guy...http://www.wesh.com/video/28984605/detail.ht ml
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656. dader
Quoting Tampa77:
NYC now issuing manual evacs
Can you manually evacuate me Tampa 77? ;)
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Quoting FLdewey:
Irene is really not looking that good.


She's looking a little emaciated from eating dry air. Her ribs are showing on the RGB.
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653. HCW
added recon info to the Level 3 radar


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Looks to be great surf for Central Fl Sat & Sun-offshore winds with a pumping swell. Actually, this storm is too close, but east coasters will get a workout...sure does look like it is going a little west though.....
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I think Irene is weakening by the hour won't be the threat she was earlier but still a big storm Probably a weak Cat 1 at most - Media Hype at its best again
Member Since: July 31, 2006 Posts: 19 Comments: 1557
Quoting hswiseman:


Maybe a small improvement in appearance in 17:45 infrared shot

yes the last 2 frames and approaching warm waters now maybe this will be the trend the models have predicted
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647. huber
Quoting ncCANEiac:
77.29 to 77.5 in 3 hours just doesn't add up to northerly movement to me!! Wilmington beware!


I agree! Looking at the visable this thing is headed toward Wilmington. Very intrested to see when the "turn" occurs. Wilmington, Wrightsville Beach, Surf City, Topsail Beaches could be in the landfall area.
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Quoting 53rdWeatherRECON:
img

It looks like it angled to the east in the last few frames.
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Quoting SWLACajun:


LA/TX border (Sulphur, LA) and you are ABSOLUTELY correct on everything you said the then some. Just saying people don't discount the energy that a storm surge has even with weakened levees. The water was going over the top of many it was so high. NYC levees may not be able to keep it from breaching height wise.


That is a good point. It will be interesting to see how high the storm surge gets in the NYC area. People often forget that if they have a 4 ft storm surge, the high swell are on top of the storm surge!

It is kind of interesting all the attention this is getting. If Houston or NOLA or Miami received 2 feet of snow in a night the northerners would be like so? Kinda weird that they are the ones in our shoes now.
Member Since: August 18, 2011 Posts: 0 Comments: 598
This is an extremely dangerous tropical cyclone that is going to impact a large and extremely populated area of the US. Gulf Stream should help her intensify probably back to a major hurricane tonight. Dry air doesn't seem to be as much of a factor compared to southwesterly shear which is tearing apart the chances of developing the southwestern outflow and southern outflow channel. Otherwise this would be the big one. however intensification til landfall is quite possible. Her major problem remains the inner core battles of which type of eye she wants, there have been EWRCs keeping her in check, otherwise she would have had a chance at category five status.
Member Since: July 29, 2011 Posts: 9 Comments: 5
643. NJ2S
Quoting zoomiami:


Depending on how the hurricanes comes into that area, it is possible that the airport may not be open or not open to commercial traffic.

Even if it is open, who knows how many people they may have to move that got stuck when the airport was closed?

Don't think changing to either of those two are going to matter, same conditions will apply. Isn't it only about 45 miles from Newark to JFK?


true but newark at least is slightly farther inland(very slightly) JFK is direcly on jamaica bay and basically right in the bullseye
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Quoting ShenValleyFlyFish:
Point well taken. However if you are depending on following blog chatter to make serious decisions you are being foolish. You would be much better off prepping and listening to your local authorities. Much as we like to mistrust government this is one instance where it is doing what it should.
understood.  for the record, I would never make a serious decision based on blog comments.  I'm in RI and far enough away from water to not be at danger (although a few blocks over might be in a worst case scenario).  regardless, I'm taking my wife and newborn and getting out of here tonight for a weekend with our parents in PA.  
there are a lot of great people here that have been very helpful with both hurricane prep info as well as minute by minute updates, neither of which the local government is providing is such detail.  the decisions I'm making are only in the extent of preparation I do to my property before leaving.  
While you are 1000000% correct that no one should be making serious decisions based on this board, the truth is that it's full of very helpful information, in fact the best I've come across.  seeing it contaminated with a political debate on the eve of landfall is a darn shame.  there will be an infinite amount of time to debate that AND those choosing to do so with have the added bonus of hindsight! 
be safe guys and gals and when in doubt, get out.
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Quoting ncCANEiac:
77.29 to 77.5 in 3 hours just doesn't add up to northerly movement to me!! Wilmington beware!


wind is picking up somewhat here..been raining as well..
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Based on 624, looks like beaucoup dry air being entrained.
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77.29 to 77.5 in 3 hours just doesn't add up to northerly movement to me!! Wilmington beware!
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Quoting drg0dOwnCountry:
But right now Irene is intensifying


Maybe a small improvement in appearance in 17:45 infrared shot

Member Since: August 29, 2005 Posts: 0 Comments: 44
I just hope people don't let their guards down and brush this storm off. So what if it doesn't hit you and you have extra water for awhile? At least you were ready.
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Quoting tiggeriffic:


lol...hubs and son got kicked off Daniel Island before noon...it was rough then...in a lull now...


gonna get rougher before it gets better. The roads to Kiawah and Seabrook were terrible back then. I'm guessing they aren't any better now.
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Quoting Cayman2010:

Whilst that is certainly the case for many of the said people, it is still a gross generalization and certainly not indicative of all. There are many people from those places listed who do not fall into this generalization and continue to follow the situation with great concern for all those in Irene's path.

They are also the ones who just aren't necessarily, being condescending and telling you what to do :-)

I lurked when it was forming, and I am lurking now. I agree lots of people come out of the woodwork when they are threatened personally, but there many who comment year round, even from here in Florida.
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poppin out for a bit...just got alert on phone bout to get nailed with another rain band soon...
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629. NJ2S
Quoting TBird78:
The news whores in NYC are finally getting wind that there's a hurricane coming and now that's all you hear.

So to them: thanks for the pre-landfall coverage of Ike, Katrina, Allison, Andrew and any of the other GOM and Florida storms.


i do agree the media can really be out there..esp for ratings.....BUT living in the Northeast I think we must take extra percaution because we r not used to these situations...I also remember following katrina from florida to NOLA b4 this blog only using TV....so to say there was no coverage is a bit exaggerated....nonetheless i agree the media needs to stick with acurate and up to date information not hyping up something for rating.
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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.