Irene continues to weaken

By: Dr. Jeff Masters , 8:46 PM GMT on August 26, 2011

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Satellite data and measurements from the Hurricane Hunters show that Irene continues to weaken. A 1:32 pm EDT center fix by an Air Force Reserve aircraft found that Irene's eyewall is still gone, and the central pressure had risen to 951 mb from a low of 942 mb this morning. The winds measured in Irene near the surface support classifying it as a strong Category 1 hurricane or weak Category 2. Satellite imagery shows a distinctly lopsided appearance to Irene's cloud pattern, with not much heavy thunderstorm activity on the southwest side. This is due to moderate southwesterly wind shear of 10 - 20 knots. This shear is disrupting Irene's circulation and has cut off upper-level outflow along the south side of the hurricane. No eye is visible in satellite loops, but the storm's size is certainly impressive. Long range radar out of Wilmington, North Carolina, shows that the outermost spiral bands from Irene have moved ashore over North Carolina. Winds at buoy 41004 100 miles offshore from Charleston, SC increased to 47 mph, gusting to 60 mph at 3 pm EDT, with significant wave heights of 25 feet.


Figure 1. MODIS satellite image of Hurricane Irene taken at 11:50 am EDT Friday August 26, when Irene was a Category 2 hurricane with 105 mph winds. The eyewall collapsed several hours before this image was taken, and no eye is apparent. Image credit: a href=http://rapidfire.sci.gsfc.nasa.gov/gallery/ NASA.


Figure 2. Distribution of Irene's wind field at 3:30 pm EDT Friday August 26, 2011, as observed by the Hurricane Hunters and buoys. The right front quadrant of the hurricane had about 90% of the storm's hurricane-force winds (yellow and warmer colors, bounded by the heavy black line between the "50" and "60" knot thin black lines.) Tropical storm-force winds (heavy black like bounding the light blue area) extended out 290 miles from the center of Irene. Image credit: NOAA/AOML/HRD.

Forecast for Irene
With its eyewall collapsed and just 18 more hours over water before landfall, Irene does not have time to build a new eyewall and intensify. The storm is too large to weaken quickly, and the best forecast is that Irene will be a strong Category 1 hurricane at landfall in North Carolina on Saturday. Based on the latest wind analysis from NOAA's Hurricane Research Division (Figure 2) and Irene's continued weakening trend, I predict that the 80-mile section of North Carolina coast to the right of where Irene makes landfall will receive sustained hurricane-force winds of 75 - 85 mph on Saturday at landfall; the 80-mile section of coast to the left will receive 55 - 75 mph winds. High wind shear of 30 knots will begin ripping into Irene Sunday morning when it is near Southern New Jersey, and more rapid weakening will occur. By the time Irene arrives on Long Island Sunday afternoon, it will probably have top sustained winds in the 65 - 75 mph range. However, since Irene is such a huge storm--tropical storm force winds extend out up to 290 miles from the center--it has set a massive amount of the ocean's surface in motion, which will cause a much larger storm surge than the winds would suggest. At 3:30 pm EDT this afternoon, a wind analysis from NOAA/HRD (Figure 2) indicated that the potential storm surge damage from Irene still rated a 5.0 on a scale of 0 to 6. This is equivalent to the storm surge a typical Category 4 hurricane would have. While this damage potential should steadily decline as Irene moves northwards and weakens, we can still expect a storm surge one full Saffir-Simpson Category higher than Irene's winds when it impacts the coast. Since tides are at their highest levels of the month this weekend due to the new moon, storm surge flooding will be at a maximum during the high tidal cycles that will occur at 8 pm Saturday night and 8 am Sunday morning. Wherever Irene happens to be at those times, the storm surge damage potential will be maximized. I continue to give a 20% chance that a 3 - 4 foot storm surge high enough to over-top the Manhattan flood walls and swamp the New York City subway system will occur on Sunday. The latest 11 am probabilistic storm surge map from NHC shows a 20 - 30% chance of a storm surge in excess of 3 feet in New York Harbor (Figure 4.) Keep in mind that these maps are calculated for normal tide level, and this weekend's high tides will be nearly 1 foot above normal.

Insurance company AIR-Worldwide is estimating that insured damages from Irene in the U.S. will be $1.5 - $6 billion. They estimate losses in the Caribbean at $0.5 - $1.1 billion from Irene.


Figure 3. Storm surge heights, in feet above normal tide level, which have a 20 percent chance of being exceeded during the next 3 days.  The graphic is based upon an ensemble of Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model runs using the current National Hurricane Center (NHC) official hurricane advisory. The exceedance heights depend on the historical accuracy of NHCs forecasts of hurricane track, and wind speed, and an estimate of storm size. Image credit: NOAA.


Figure 4. Overall chance that storm surges will be greater than 3 feet above normal tide levels during the next 3 days.  The graphic is based upon an ensemble of Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model runs using the current National Hurricane Center (NHC) official hurricane advisory.  Storm surge probabilities depend on the historical accuracy of NHCs forecasts of hurricane track, and wind speed, and an estimate of storm size. Image credit: NOAA.

Links
For those of you wanting to know your odds of receiving hurricane force or tropical storm force winds, I recommend the NHC wind probability product.

Wunderground has detailed storm surge maps for the U.S. coast.

The National Hurricane Center's Interactive Storm Surge RIsk Map, which allows one to pick a particular Category hurricane and zoom in, is a good source of storm surge risk information.

Wunderblogger Mike Theiss is in Nassau, documenting the storm's impact on the Bahamas.

Internet radio show on Irene at 4:30pm EDT
Wunderground meteorologists will be discussing Hurricane Irene on a special edition of our Internet radio show, the Daily Downpour, today (Friday) at 4:30pm EDT. Shaun Tanner , Tim Roche, Angela Fritz, and Rob Carver will take your questions. The email address to ask questions is broadcast@wunderground.com.

Jeff Masters

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Quoting 900MB:
NYC reporting. Outflow clouds have moved into the city and it is muggy as heck. The city has been in panic mode all day, ever since Bloomberg announced that mass transit will be shut completely tomorrow. Shutting mass transit means that all of the stores will close 2 hours earlier. There were long lines to get into the local fairway supermarket and 2 security guards at the door controlling the crowds. Everyone was civil but plenty of nervous energy going around. There was a rumor that a curfew would be instituted as well.
What concerns me most is if this is a total dud. Believe me, next time NYers will think they are crying wolf again and then disaster could ensue.


That's the lose-lose situation that the NHC is in right now. Either it hits and is catastrophic or it hits and is nothing and then no one will pay attention the next time a big storm comes their way.
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400. JLPR2
GFS and EURO differ significantly in possible Jose's track.

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Quoting 900MB:


hmm definitely a redevelopment of some deep convection around the center. I disagree with the somewhat wild predictions that this thing will restrengthen to a cat 3, but a cat 2 is probably a bit more of a possibility than advertised.
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Is it true the death texas ridge is forecasted to completely break apart? if it does the US gulf coast will now be at risk for tropical systems too....
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397. hamla
imo
as yogi berra said

it aint over till its over

dont count irene out she is too big
ts force winds for up to 24 hours for some folks along the east coast big waves storm surge, flooding from surge,flooding from rain,power out for weeks in some cases,trees down etc
this aint fun
been there done that
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JLPR, there is nothing that tells you that Jose will go out to sea, it will head WNW cuase a weakness in the ridge then Head W when the Ridge build back in..
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oops, mistake
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394. 900MB
Quoting 900MB:
Rainbow looking much better. Pressure drop to 949? Any chance at one last pop?
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393. 900MB
Rainbow looking much better. Pressure drop to 949? Any chance at one last pop?
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Quoting rkay1:
If by NC you mean curving out to sea, than yeah.  The pattern has been Mexico and curving out to sea.  With the exception of Irene I would say that pattern still holds.  It took nearly perfect timing to hit the CONUS and at times Irene did look she might of had a chance to curve as well.  IMO, Irene will be the last real threat to the US this season unless the environment really switches around.



LOL i guess we can all cancel the rest of the season now because this guy said this is it
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Quoting leftlink:


I am wondering why they spend so much $$ on the dropsondes but have not fixed key buoys in the atlantic, i.e. in the NE quadrant of Irene:

http://www.ndbc.noaa.gov/station_page.php?station =41002

It would be nice to have that working again -- and also to have buoys off the coast of the Bahamas and the DR, where there was very little live data on storm intensity.



because every time taxes go up people complain, and that's where the money would come from to pay for these expensive additional buoys. In fact forecasts would probably be a heck of a lot more accurate if people were willing to put more tax money into the field. Are they willing to? Nope.
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389. yoboi
central GOM needs to watch next week look south of cuba now thats what joe was talking about plus the hight over texas finally breaks next week
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Quoting WeatherNerdPR:
Has Irene been moving NE? Link


No, there is new convection building in areas that haven't had them, and thus it makes it look like the storm is moving that direction.

Quoting Tazmanian:




????


The winds, lol. They had to have just gust over 50 mph, probably near 60 mph.
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386. JLPR2
Quoting lottotexas:
conus interaction from any of these ??


GFS wants to develop

Jose (CV storm) Out to sea
Katia (Caribbean Storm, GOM)
Lee (Subtropical Atl)

Lets see just how much materializes.
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Quoting cntrclckwiseSpenn:



What part of the Gulf is Bastardi talking about? Anyone know? The only thing I've seen is a storm developing in the BOC off Mexico. Does he mean Texas, Central, FL panhandle/FL west coast??


Who knows, the guys clearly lost his mind.
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lottotexas,
Too early to tell on the Cape Verde storms, but BOC system could pose a threat to TX(not much of a threat, more beneficial) prob Strong TS... My reasoning to it going to TX is the TX ridge is forecasted to break down next week, and a trough is suppose to sweep in right as the storm forms, so it would draw it north... Hermine(2010) type Track
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For those so unwilling or to arrogant to read the comments of a HS drop out. I am A member of MENSA with an IQ that places me in the top 1%. I have read and tracked weather events since I was in grade school I am more than capable of comprehending the data presented. If you want to dispute the veracity of my post please do so. But please provide facts to explain my errors.

Sorry that my intro threw you.
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"PRZEDCASTER", HI Mark Good to see you are back posting.
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Link

Would not want to be in the Philippines.
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Has Irene been moving NE? Link
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What is with the models which suggest a strengthening ?
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Quoting ncstorm:
Tweet from Joe Bastardi
BigJoeBastardi Joe Bastardi
Storm has not started deepening, I still think it will. Convection should refire and eye re develop later tonight

BigJoeBastardi Joe Bastardi
Watch the gulf for next weekend, the east coast may be threatened by Sep 10 again. It fits pattern



What part of the Gulf is Bastardi talking about? Anyone know? The only thing I've seen is a storm developing in the BOC off Mexico. Does he mean Texas, Central, FL panhandle/FL west coast??
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377. 900MB
NYC reporting. Outflow clouds have moved into the city and it is muggy as heck. The city has been in panic mode all day, ever since Bloomberg announced that mass transit will be shut completely tomorrow. Shutting mass transit means that all of the stores will close 2 hours earlier. There were long lines to get into the local fairway supermarket and 2 security guards at the door controlling the crowds. Everyone was civil but plenty of nervous energy going around. There was a rumor that a curfew would be instituted as well.
What concerns me most is if this is a total dud. Believe me, next time NYers will think they are crying wolf again and then disaster could ensue.
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Quoting washingtonian115:
I'm with a friend right now that's been storm chasing for a few years now.So I decided to join him.Hey why not.This could be a heck of an experience.


Stay safe!
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Quoting TropicalAnalystwx13:
Holy Crap!




????
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373. HCW

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60 knot winds extend 180 miles North:

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Quoting HurricaneDean07:
So far according to the models;
TC formation expected...
Jose, Cape Verde storm that is developed by
GFS, HWRF, EURO, NOGAPS, CMC...
Katia, BOC system developed by EURO, and NOGAPS
Lee, Another Cape Verde system behind it, at the end of the run in GFS(A few others)
conus interaction from any of these ??
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Holy Crap!
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Quoting Dennis8:


Welcome back...
Did u get your people out in time, Dennis?

Quoting BahaHurican:
Finally, yes.
I take this back. Still a phone problem.
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Quoting PureScience:
I am just a high school drop out but I can't help but wonder why we even spend a dime sending Hurricane Hunters into storms to get precise measurements when the guys and gals with the degrees resort to assumptions and guesses of the storms intensity when they don't get readings to support their hype.



I am wondering why they spend so much $$ on the dropsondes but have not fixed key buoys in the atlantic, i.e. in the NE quadrant of Irene:

http://www.ndbc.noaa.gov/station_page.php?station =41002

It would be nice to have that working again -- and also to have buoys off the coast of the Bahamas and the DR, where there was very little live data on storm intensity.

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Quoting PureScience:
"I am just a high school drop out but I can't help but wonder why we even spend a dime sending Hurricane Hunters into storms to get precise measurements when the guys and gals with the degrees resort to assumptions and guesses of the storms intensity when they don't get readings to support their hype."

My thought on that is that the planes go out and take readings. The data they bring back is then interpreted. Part of the interpretation would also include data from other sources. Then an reasonable conclusion is drawn.

Not all weatherman see the same things when looking at their data and some have more experience than others. Some go with pure data, some add in their gut feeling. It's not an exact science. That's why you see statements that are a bit vague or hedging. IMO.
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Bastardi and his patterns.

I could say that. More storms have been taking a route between NC/Bermuda over the last few years.

Now give me that money.
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Quoting ncstorm:
Tweet from Joe Bastardi
BigJoeBastardi Joe Bastardi
Storm has not started deepening, I still think it will. Convection should refire and eye re develop later tonight

BigJoeBastardi Joe Bastardi
Watch the gulf for next weekend, the east coast may be threatened by Sep 10 again. It fits pattern


If I were his boss, I would have fired him a long time ago.
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306 Patrap [Irene satellite photo animation]

?Finally taking the northeastward motion that was predicted?
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Quoting HurricaneLovr75:
Here in Plymouth county Mass. I expect to see wind gusts but no sustained winds. Glad she weakened. But I believe that nobody in Mass will ever believe a forecasted Hurricane except people on Cape Cod. I thought this was going to be my chance to see sustained hurricane winds. Two straight storms , Earl last year, that don't live up to the hype. I will have to be laughed at again in work for saying that this is the one. One day it will happen and it might be the next one.


You may be laughed at, but it's a hell of a lot better then being under prepared when the inevitable big storm hits.
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So far according to the models;
TC formation expected...
Jose, Cape Verde storm that is developed by
GFS, HWRF, EURO, NOGAPS, CMC...
Katia, BOC system developed by EURO, and NOGAPS
Lee, Another Cape Verde system behind it, at the end of the run in GFS(A few others)
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Quoting rkay1:
Irene trolled everyone for the past 2 weeks.  Don't get me wrong, a CAT1 is still a storm by any means, but after all this drama I would of expected Irene to be related to Andrew.  After targeting the entire East coast, forecasted at times to be a CAT4, I just expected a completely different storm.  This is great news!


Why the surprise? Intensity forecasts are well advertized to be poor. Just be thankful Florida and North Carolina both dodged a serious situation. The Bahama's however were not so lucky and received the max that Irene had to offer. A serious situation still applies to the NE in the form of rain and storm surge, hopefully they can dodge a bullet as well. That would be the best outcome that could be expected with Irene at the moment.
Member Since: August 19, 2005 Posts: 5 Comments: 5046
Tweet from Joe Bastardi
BigJoeBastardi Joe Bastardi
Storm has not started deepening, I still think it will. Convection should refire and eye re develop later tonight

BigJoeBastardi Joe Bastardi
Watch the gulf for next weekend, the east coast may be threatened by Sep 10 again. It fits pattern
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Quoting wunderweatherman123:

la nina AGAIN this winter 0__0 wow
More dry conditions in Texas then.Just no break for them.Next hurricane season could be interesting once again.This could break the pattern.
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I wouldn't trust #349...
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Quoting NoVaForecaster:


Appears to be shielding it from the core pretty well right now.



This is not true, the dry air still in the core in a big way. You get the best picture looking at the color infrared satellite photos... here is the photo at 1:15pm eastern time:

16:15Z


and here is the photo at 6:15pm, or 5 hours later:



What has happened to Irene is that land interaction made the storm so big and spread out that her wind field expanded a bit too much, and thus she is drawing in air from all the land masses she passes.

First she drew in dry air from the DR, then from cuba, then Florida, and now Georgia. The only time she rapidly intensified was in the approach to Puerto rico completely over water, and then when she passed Hispaniola and had open water to her southwest, and then finally when she went north of cuba.
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Quoting washingtonian115:
I'm with a friend right now that's been storm chasing for a few years now.So I decided to join him.Hey why not.This could be a heck of an experience.


Heck yeah.....I would like to myself....I think :/
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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.