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 900MB:


Well he sure as heck downcasted this thing. I am giving this thing until a few hours to NC to see if it re-intensifies (it might, these hyped forecasters may have just lost patience with "the worst storm since 1938"). NC is my benchmark. If it hits NC at less than 100mph, my guard is officially down for NYC/Long Island!


Mine too.
Hitting N Carolina should weaken it enough and disrupt the surge substantially before it emerges back over water.
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Quoting MahFL:


Video games.
As a gamer, I disagree.

It's more towards texting.
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i will admit it looks like i will be wrong,the way she improved this am,thought irene might get to 115-120. she's fighting the dry air and shear,but appears its going to be a losing battle for her to strengthen. im gonna start calling her"dryrene"...lol...still a dangerous storm surge issue,and high precip event..but we get lucky and hopefully nothing catastrophic...now as i say this,she will strengthen....lol. TWC really playing this up big time....geeeeeeeeeeezzzzzz...just tell the truthful facts..guess they need rating points..hell,they talking about evacuating elderly from hospitals
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Quoting vortextrance:
Irene is not collapsing, significantly winding down, or no longer a threat. Anyone who says that has no credibility. Irene is highly unlikely to weaken significantly, if at all, in the next 24 hours.


I agree with you that Irene is still very much a threat but she going downhill, and maybe in a hurry. HH will tell us the tell on the next couple hrs. She's already went from 115 to 105 today. So she's already showing that trend and her WV, Shortwave and AVN loops are all pointing to a collasped core. Anyone have a Microwave Sat pass of her?
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Quoting MahFL:


Video games.


n txtng
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Quoting MoltenIce:
It's still a hurricane, a large one too.


Oh I totally agree, but they were predicting Cat 4, not a Cat 2. And that makes a huge difference, no?
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171. MahFL
Well convection is re-fireing now on the NW eyewall...just saying !
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170. 900MB
Quoting reedzone:
Dr. Masters is not god, ok? He was just putting out his OPINION on the storm, it's not a fact Irene will rapidly weaken. The storm is not winding down very fast, in fact an eye has popped back out in the latest visible frames and structure has improved. People should NOT let their guard. I have a feeling we will loose ALOT of lives this weekend because you all are letting your guards down. Good luck, seriously :/


Well he sure as heck downcasted this thing. I am giving this thing until a few hours to NC to see if it re-intensifies (it might, these hyped forecasters may have just lost patience with "the worst storm since 1938"). NC is my benchmark. If it hits NC at less than 100mph, my guard is officially down for NYC/Long Island!
Member Since: June 11, 2006 Posts: 0 Comments: 684
Quoting P451:
Those in NJ, NY, CT should look to the following storms for the range of damage they could expect from Irene come Sunday.

Hurricane Gloria - 1985
Hurricane Bob - 1991
Nor'Easter - December 1992
Superstorm - March 1993

These systems represent what you should expect and prepare for from Irene.

This isn't 2009 Hanna. This also isn't Katrina.

Flooding and falling trees is the primary threat. Direct wind damage to buildings is not.


Hey P,

It's not to late to add more cheetos and slim-jims to the supply kit.

What are your thoughts on Irenes current state?
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Quoting hulazigzag:
I think something to be noted was how excellent the NHC has done with the track forecast. The amount of recon and data that were collected have helped them nail down the track. They still have a problem with intensity but hell the last few years at least they can tell us where it's going.

The model done an incredible job so far and they call for a weakening and gain before landfall if i understand that right.
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Quoting ConnecticutWXGuy:


I think in terms of how many people are affected, it will be a bit worse than Bob or Gloria. Gloria hit southeastern New England and caused some decent damage in that area, but I lived a mere 40 miles from landfall and all we got was a couple thunderstorms and some steady rain that added up to under 2 inches. Bob took a similar path and all I got was overcast skies and sprinkles. So I think this storm is a lot more serious in terms of how widespread it will be.


My advice for Northeast coast residents for Irene is this: Think of the worst storm in your local area. This one will be worse.

Maybe the 20 mile stretches where the eye of Bob and Gloria made landfall won't have a worse storm. Maybe Battery Park won't be as bad as 1992. But everywhere else it will be worse.
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Hurricane Irene will most likely be retired when all is set and done. the storm will also be one of the top great Northeastern Hurricanes.
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165. HiWay
Wind was NEVER the threat for this storm! It's the sheer size and with that comes the surge, duration of heavy rainfall and sheer coverage area! A storm this big, especially falling apart will also spawn more tornado capable storms. Mixing in with the Jet Stream will not help matters either. A lot of people focus FAR FAR too much on the little wind speed number. Sure it's the impressive big number but that is NOT the danger to North Carolina, Virginia or the North East.
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164. MahFL
Quoting BobinTampa:



Okay, this is the absolutely LAST time I will post this. It is spelled L-O-S-E!!!!

Why do people constantly misspell 'lose' as 'loose'????



Video games.
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you would think that cool dry air would aid the storm, by providing buoyancy to the warm humid air raising through it...
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The problem is, is that this iis still a huge Hurricane with damaging winds and potentially deadly storm surge. I think reed, in his heavy handed and clumsy way, is simply trying to belay his fear that the normal person will see Irene weakened and go "no big deal"
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I think something to be noted was how excellent the NHC has done with the track forecast. The amount of recon and data that were collected have helped them nail down the track. They still have a problem with intensity but hell the last few years at least they can tell us where it's going.
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Like I said, plenty of reasonable and wise people here :)
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Quoting BobinTampa:



Okay, this is the absolutely LAST time I will post this. It is spelled L-O-S-E!!!!

Why do people constantly misspell 'lose' as 'loose'????


Oh there is "your" and "you're", "their" and "they're", "its" and "it's", and the list goes on...

Hopefully it's just because they're lazy and not because they're uneducated...
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I have a friend who lives in Wildwood/Morey Piers area and when I called him on Tuesday he was all ..meh, no big deal.

As of yesterday that all changed and he was out of there (Mandatory Evacuation) so people are taking this seriously. It will be interesting to see how the Piers deal with this storm.

I know amusement parks and roller-coasters are not a primary concern but I have really enjoyed Morey's, Steel Pier and the rest of the rides along the Jersey Shore. This will be a terrible economic impact to have this happen right before Labor Day.

I am hoping for the best for everyone in the path of Irene and I really hope the worst case scenario does not occur for New York City and the rest of the North East this weekend.
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Update
*All graphics can be magnified by clicking on them (they can also be further magnified in the new window by clicking on the graphic)






Member Since: June 29, 2009 Posts: 13 Comments: 5315
Quoting P451:
Those in NJ, NY, CT should look to the following storms for the range of damage they could expect from Irene come Sunday.

Hurricane Gloria - 1985
Hurricane Bob - 1991
Nor'Easter - December 1992
Superstorm - March 1993

These systems represent what you should expect and prepare for from Irene.

This isn't 2009 Hanna. This also isn't Katrina.

Flooding and falling trees is the primary threat. Direct wind damage to buildings is not.


I think in terms of how many people are affected, it will be a bit worse than Bob or Gloria. Gloria hit southeastern New England and caused some decent damage in that area, but I lived a mere 40 miles from landfall and all we got was a couple thunderstorms and some steady rain that added up to under 2 inches. Bob took a similar path and all I got was overcast skies and sprinkles. So I think this storm is a lot more serious in terms of how widespread it will be.
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Quoting BobinTampa:



Okay, this is the absolutely LAST time I will post this. It is spelled L-O-S-E!!!!

Why do people constantly misspell 'lose' as 'loose'????


Easy Bob, sounds like you starting to loose it! :p
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Quoting P451:


Does anyone recall the environment, moisture wise, that Ike was in?

Irene is in some very dry air and will be begin entraining the continental air into it's core come tomorrow.

Ike didn't have the same continental processes affecting it. I don't recall the water vapor field around him at that time.


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Quoting MoltenIce:
Nanmadol literally stalled off the coast of Luzon. Any serious damage? Nanmadol still looks like a beast. I think it's veering off to the northeast.

Signal #4 raised in Cagayan.... no serious damage reported on the news but may get reported tomorrow or as it leave PAR.
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All convection gone before morning.
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Quoting WeatherMSK:
Anyone can look at this storm on satelite and make common sense that this is one hell of a storm not to be taken lightly. Wake up people.
Whos sleeping. Been up six six this morning thank you very much.
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148. jpsb
Wow, from near cat 4 to lucky to maintain cat 1 in an hour or two. Did someone fire up the weather machine? I'll be back later to see how this story ends. Things looking much better for the N.C. and places north so that is good news.
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Quoting WeatherMSK:
Anyone can look at this storm on satelite and make common sense that this is one hell of a storm not to be taken lightly. Wake up people.


Indeed. Still a very powerful storm.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Irene is not collapsing, significantly winding down, or no longer a threat. Anyone who says that has no credibility. Irene is highly unlikely to weaken significantly, if at all, in the next 24 hours.
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Battered by dry air.
Member Since: October 25, 2008 Posts: 58 Comments: 6257
Quoting KEEPEROFTHEGATE:


Amazing.
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Maximum sustained winds have decreased to near 105 mph
Member Since: August 15, 2008 Posts: 0 Comments: 446
Anyone can look at this storm on satelite and make common sense that this is one hell of a storm not to be taken lightly. Wake up people.
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Quoting drg0dOwnCountry:

She approaches more warm waters now/soon


Warm water isn't everything, as we've seen the past 3 days. She had plenty of warm water. However, she is also approaching an area of increased wind shear and dry continental air.

She is more than likely done strengthening.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting reedzone:
Dr. Masters is not god, ok? He was just putting out his OPINION on the storm, it's not a fact Irene will rapidly weaken. The storm is not winding down very fast, in fact an eye has popped back out in the latest visible frames and structure has improved. People should NOT let their guard. I have a feeling we will loose ALOT of lives this weekend because you all are letting your guards down. Good luck, seriously :/



Okay, this is the absolutely LAST time I will post this. It is spelled L-O-S-E!!!!

Why do people constantly misspell 'lose' as 'loose'????

Member Since: August 14, 2008 Posts: 0 Comments: 545
Here's something to keep in mind for us Northeasterners.



It's been a very wet spring, in some cases the wettest on record and elsewhere it was very close. This has allowed for extra foliage to grow in deciduous forests than in a normal year meaning the trees will have that much extra surface area to catch Irene's wind as it comes plowing north. This means trees are even that much more vulnerable to being toppled from wind saturated soil.
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137. 996tt
Quoting cloudburst2011:
jim cantore must be really depressed the way he was hyping this storm up last night in new york...


Yep. Him and Abrhams have been acting like kooks for several days, but alas, it does get rating and makes their pay checks bigger.
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Quoting ecupirate:


He is at school right now. Im willing to bet he was just a troll posing as an elderly man.


Could it be he is actually busy boarding up and getting out as he said yesterday? Just why do you want to know where he is? He's a nice guy no matter what so what's it to you? You looking more like some of the trolls in this blog. Back to lurking
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TD10's a goner.
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Quoting MississippiWx:
The lack of any significantly cold cloud tops around the eye (or what's left of the eye) should tell us that Irene is simply maintaining intensity. If we start seeing hot towers, then a strengthening phase may begin. However, time is running short for that to happen.


She approaches more warm waters now/soon
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Member Since: July 15, 2006 Posts: 175 Comments: 54858
Update from Sneads ferry NC, was going to decide this evening weather to Head inland or not. Water is really choppy, and only a 10-15 breeze. Think Im riding this one out.
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129. dader
Quoting reedzone:
Dr. Masters is not god, ok? He was just putting out his OPINION on the storm, it's not a fact Irene will rapidly weaken. The storm is not winding down very fast, in fact an eye has popped back out in the latest visible frames and structure has improved. People should NOT let their guard. I have a feeling we will loose ALOT of lives this weekend because you all are letting your guards down. Good luck, seriously :/


My problem with Reed's comments are he puts words in Dr. Master's mouth.

1. Masters did not say that it will weaken rapidly.
2. He did not say it will wind down fast- he said the exact opposite.
3. He talked about the eyewall and said he did not believe it had the time over water to replace it.
4. He never told anyone to let their guard down. Ever- he merely is stating his opinion based on facts.
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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.