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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229. 900MB
Quoting ILwthrfan:
We are approaching Dinurnal minimum as well so that is playing a factor into her warmer cloudtops.


She does have a tendency to blow up at the end of the day. Guess one more chance.
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Interestingly, the 06Z HWRF Simulated Reflectivity shows Irene having a lot of problems with her eye and shows almost an open storm (albeit a strong one) after crossing the Outer Banks.

Link to Simulated Reflectivity

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Dr. Jeff Masters said:

"It looks like Irene will pass New Jersey during low tide, which may limit the storm surge inundation to 3 - 6 feet there."

**** I think you have a type-o in your analysis here. NDFD is posting 8am Sunday just off of Central Jersey. High tide Sunday 8/28 at Atlantic City is 7.14am with a departure of +4.44.****

http://tidesandcurrents.noaa.gov/noaatidepredicti ons/NOAATidesFacade.jsp?Stationid=8534720&bmon =08&bday=27&byear=2011&edate=&time length=daily
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Quoting lowerbamagirl:
I have a technical blog question. Is there anyway to ignore people and actually get back to the page you were on? I have tried everything including the back button, but to no avail. I rarely ignore, but during an active landfalling system, my list grows extensively!


I use FF and after adding an ignore, I use the pull-down next to the back button and select three down to get to where I was reading. Or... hit back button 2 or 3 times. Note, the ignored user will still be there until you press 're-load' or 'refresh'.
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Irene could still strengthen a little,but that doesn't really matter too much given the size of this storm. Imo
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224. MahFL
Quoting JerseyShoreGirl:
I am going to wait to see what happens in NC before I jump the gun here in NJ. I will still head all the warnings, but the last update actually makes me feel a bit more calm.


It's heed not head lol.....lmao....
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Quoting oracle28:


Fish Storm? JUST KIDDING!!!
Nope right on NHC track, I'd say.
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221. 996tt
Quoting ncstorm:
You guys are reaching..I saw NOTHING in the NHC previous discussion that said Irene will dissipate into nothing..not even a "might"..people in the path of Irene please follow your local NWS and NHC for any information ..the next advisory is at 2pm..


They won't ever say that. Better to have people prepared just in case something bad happens at the very last minute and everyone is caught off guard and unable to escape.

Should be a much better scenario for everyone and no skyscrappers in NYC falling over with millions displaced. Dang, seems like some are disappointed that is not going to happen. Well, gotta run. Just taking a breather and checking phone. Winds should be shifting here soon and waves, althought not as large or Floyd, Bill et al, are still better than usual cept for the 90 % 2 block closeouts . . .
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218. MahFL
Irene wobbled west.
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Quoting wunderweatherman123:
just curious is irene done stregthining or what?

She has weakend a bit but the question is open if she has time to regain
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Quoting wxobsvps:
202...

after you click Update Ignore List, just go to BLOGS then Jeff Masters. The name you Ignored may not show up on the list when you hit Update, but the posts will be gone when you get back to the Blog.


Thank you for answering, as to the post immediately above yours I will try it first on him.
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Quoting lowerbamagirl:
I have a technical blog question. Is there anyway to ignore people and actually get back to the page you were on? I have tried everything including the back button, but to no avail. I rarely ignore, but during an active landfalling system, my list grows extensively!
I right click on the ignore button; click on open in a new tab; go through the instructions, then close the tab and I am back to where I was. HTH POP
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Quoting lowerbamagirl:
I have a technical blog question. Is there anyway to ignore people and actually get back to the page you were on? I have tried everything including the back button, but to no avail. I rarely ignore, but during an active landfalling system, my list grows extensively!


I have the same issue sometimes. I usually write the post and page # down before I do anything, then go back to it myself.
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09L/MH/I/C2
RI FLAG (off)
RD FLAG (flag)
MARK
30.48n/76.98w





ALWAYS FOLLOW NHC/TPC FORECASTS FOR ALL WARNINGS REGARDING THIS STORM
Member Since: July 15, 2006 Posts: 169 Comments: 53296
just curious is irene done stregthining or what?
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I would think for the next 8 hours or so there could still be potential intensification. There is alot of warm water underneath Irene and she should be further away from the Florida coastline on the southwest side. The landmass curves away from the storm in this time period of movement so there should probably be less land interaction on the southwest side of the storm.
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207. 996tt
Quoting lowerbamagirl:
I have a technical blog question. Is there anyway to ignore people and actually get back to the page you were on? I have tried everything including the back button, but to no avail. I rarely ignore, but during an active landfalling system, my list grows extensively!


Yep, just don't read post you don't want to read.
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You guys are reaching..I saw NOTHING in the NHC previous discussion that said Irene will dissipate into nothing..not even a "might"..people in the path of Irene please follow your local NWS and NHC for any information ..the next advisory is at 2pm..
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How is it that a hurricane is 400 miles away... and there isn't even a swell?
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Quoting HurricaneHunterJoe:
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


They were relaying mayor's words of evacuating elderly from hospitals in zone A (flood potential area). Please say the whole thing and not take out of context. Was a wise move considering the anticipated storm surge Dr. Masters referred to. On another note, imagine what will happen to all the rats in the underground stormwater and sewer systems below NYC when they and the subways flood. Don't they usually go for higher ground? Like up into buildings etc. Shiver, Shiver
Member Since: September 2, 2010 Posts: 0 Comments: 81
I am going to wait to see what happens in NC before I jump the gun here in NJ. I will still head all the warnings, but the last update actually makes me feel a bit more calm.
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I have a technical blog question. Is there anyway to ignore people and actually get back to the page you were on? I have tried everything including the back button, but to no avail. I rarely ignore, but during an active landfalling system, my list grows extensively!
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Quoting StormJunkie:


I hope this image of a deteriorating storm does not give coastal residents a false since of security. The winds can come down some fairly quickly; but the storm surge she brings is still going to be awfully nasty.
but ya know stranger things have happen this could very well just disappear into nothing but some rains gusty winds and heavy surf typical rainy windy day nothing more noting less watch wait see
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Obama says Hurricane Irene "extremely dangerous"

(Reuters) - President Barack Obama on Friday warned Americans to take Hurricane Irene seriously and urged them to obey orders to evacuate from the path of what is likely to be an "extremely dangerous and costly" storm.

"All indications point to this being a historic hurricane," Obama said in a statement to reporters from the farm where he is vacationing on this island off the Boston coast.

Fifty-five million people are potentially in Hurricane Irene's path, from the Carolinas to Cape Cod on the East Coast, and tens of thousands are evacuating as cities including New York and Washington brace for the powerful storm to hit. http://www.reuters.com/article/2011/08/26/us-stor m-irene-obama-idUSTRE77P4IM20110826

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Quoting P451:


They really sampled this storm and it's forward environment extensively even deploying weather balloon throughout the eastern 1/3rd of the US.

They have a lot of very precise data to work with and that would explain why the track has been so good.

I still say we just don't know what to expect up in NJ/NY/CT until we see how Irene interacts with North Carolina and what her heading and structure is after the fact.

However given how good the data has been I don't have much cause to question the present forecast track. It seems good.




Agree completely.
Member Since: June 29, 2009 Posts: 13 Comments: 5300
Quoting KEEPEROFTHEGATE:
Looks to be turning NNE
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Quoting HurricaneHunterJoe:
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


TWC has been in a downward spiral for a couple of years now. How about Die-rene instead of Dryrene?
Member Since: June 29, 2009 Posts: 13 Comments: 5300
192. 996tt
NHC tracking has been particularly good, epsecially better than 2008 and pre-2008
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As I posted yesterday. Irene reminds me of Hurricane Ike.

Ike's eyewall collapsed as well but it maintained it's Cat 2 strength and Cat 4 Storm Surge across the western gulf. That energy doesn't stop on a dime.

Irene will remain a coastal and inland issue up the east coast.
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Hurricane hunters fly into eye of storm
NBC's Peter Alexander reports from Biloxi, Mississippi where he joined a crew of hurricane hunters on an 11-hour flight that took them into the eye of Hurricane Irene to learn more about the storm's strength and potential threat.

Visit msnbc.com for breaking news, world news, and news about the economy

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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'????



I'm putting the over/under at 14 days.
Member Since: August 29, 2010 Posts: 0 Comments: 5236
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'????



actually, "lose" is spelled kinda funny. I mean look at "close", using that pronounciation we should pronounce "lose" as "lowz" or maybe "lowce". It would make more sense to spell "lose" as "looze" or maybe "luze".

So I can see why a lot of people make that mistake, especially when typing fast. In fact when you think about it, it's downright silly the way "Lose" is spelled. I mean, the only difference in the way "Lose" and "Loose" are pronounced is the "S" or "Z" sounds, so let's just change the number of "O"s, yeah that makes sense.
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Quoting HurricaneHunterJoe:
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


I know very little, but I know more than all at the Weather Channel. They're just selling stuff.
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We are approaching Dinurnal minimum as well so that is playing a factor into her warmer cloudtops.
Member Since: February 2, 2010 Posts: 0 Comments: 1456
Quoting reedzone:
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.
Probably, but let's not hope that it's a total calamity instead of just a regular calamity. You need to calm down. Nobody's letting their guard down here. Dr. Masters and the NHC are talking science and probabilities. Their resources far exceed your own mind. You really owe the Dr. an apology, imo.
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its your're opinion that their are knot typing it good

Quoting ReefMaster:

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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The personal attacks are starting again. I am flagging every one. Disagree with facts, not personal attacks.
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181. 996tt
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.


I'd paddle out in that thing. Well am about paddle back out down here in windy Cocoa area. Cat 1 and 2, ride those out in my house and the kooks from TWC will probably be out on the beach when this rolls through or hanging in their motorhome staying dry between shots at or on the beach somewhere. Cat 3 is when start to worry, unless you live on an island and your house is about 5to 10 foot about sea level like we saw at Galvestin in Ike and one of my places in Navarre during Ike which ended up in the sound when surge when completely across the island. If your in a safe structure, cat 1 or 2 not bad. Just no A/C and unsafe water for days and days tends to suck afterwards.
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I hope this image of a deteriorating storm does not give coastal residents a false since of security. The winds can come down some fairly quickly; but the storm surge she brings is still going to be awfully nasty.
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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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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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