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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Dry air still a problem, but Irene is looking a little better than she did earlier today.



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Quoting CosmicEvents:
There was a report I saw today on CNN that said that some of the older locals, who had rode out every storm for the last 40 years, were leaving for this one. Because of the direction and water rise from both sides. It was something that worried the real old-timers.


Yah, I can see that. The biggest problem is track and positioning. Most of the locals here don't look at the wind speed. If the storm is angling in such a way that the NE quad is going to run roughshod over say... Oregon Inlet north, then they know what is gonna flood due to storm surge. Then after the storm passes, again, depending on track, they worry about Sound side flooding.

Most of the OBX residents I know who were coming inland at least here to Elizabeth City, were Sound side residents. They'd gotten burned hard during Isabel, and didn't want to go through that again.

Not trying to downplay ANYTHING, just making a statement that the OBX residents for the most part have their head screwed on tight. If they're sitting tight, they're MORE than prepared for Irene.
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Quoting ShenValleyFlyFish:
Anybody done the math? How many sq mi/km is Europe? How many sq mi/km Emily. I could do it but it would be with pencil and paper. Some of you young guys out there ought to be able to do it in a flash. Give you something to do beside think up your next troll fart.


Europe is 3,837,081 sq miles
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Quoting Patrap:
# 725

I'd modify that or you'll be on a permanent wu-cation



oh come now...with all the stuff that gets left up on this blog? is that better?
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747. Gorty
Irene is getting convection to more spots around her eye. Looks like the dry air is letting up a bit on her look at the space where the air was, it is now filling in.
Member Since: November 8, 2008 Posts: 12 Comments: 1058
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 809
NWS STORM PREDICTION CENTER NORMAN OK
815 PM EDT FRI AUG 26 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

FAR EASTERN NORTH CAROLINA
COASTAL WATERS

EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 815 PM
UNTIL 500 AM EDT.

TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 30 STATUTE
MILES EITHER SIDE OF A LINE FROM 40 MILES NORTH NORTHEAST OF CAPE
HATTERAS NORTH CAROLINA TO 15 MILES SOUTHWEST OF WILMINGTON NORTH
CAROLINA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 808...

DISCUSSION...DISCRETE SHOWERS AND TSTMS WITH LOW LVL ROTATION
EXPECTED TO PERSIST ALONG ARC OF LOW LVL CONFLUENCE NOW LOCATED OVER
THE NC CSTL WATERS ON NRN FRINGE OF CIRCULATION OF HRCN IRENE. AS
IRENE CONTINUES SLOWLY NWD...THE CONFLUENCE BAND SHOULD GRADUALLY
LIFT NWD...WITH ADDITIONAL WARMING/MOISTENING OF THE BOUNDARY LAYER
OCCURRING IN ITS VICINITY. THIS MAY ALLOW THE LOW LVL
CIRCULATIONS...AND THEIR ATTENDANT TORNADO THREAT...TO SPREAD
FARTHER W WITH TIME...IMPACTING THE BARRIER ISLANDS FIRST
AND...LATER THIS EVE/EARLY SAT...FAR ERN PORTIONS OF THE NC CSTL
PLN. GIVEN EXISTING WIND PROFILES...AND THE LIKELIHOOD FOR SOME
STRENGTHENING OF THE LOW LVL WIND FIELD IN WW AREA LATER
TNGT...EXPECT THAT TORNADO RISK WILL INCREASE WITH TIME...ESPECIALLY
OVER FAR ERN AND NERN NC

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 12035.


...CORFIDI


Member Since: July 3, 2005 Posts: 426 Comments: 128654
745. HCW

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Quoting presslord:
Do women really think that looks good?!


That would be a big NO..NO..NO for me..:O
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Quoting tiggeriffic:


sup...did you get the pic i sent ya?


yes ma'am...lottsa water...the Ashley River was above Murray Blvd
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The biggest joke for me so far with this storm is that on Tuesday and Wednesday a lot of the tourists left and on Wednesday night a lot of the locals checked in. Normally the last places on any island with power are the hotels. So a lot of the local residents used the hotels as "storm shelters" to get away from the discomfort of homes without power and water...
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Quoting breald:


I think Brian Williams, who is reporting live from NJ made that comparison. TWC was just talking to him. :)
Anybody done the math? How many sq mi/km is Europe? How many sq mi/km Irene. I could do it but it would be with pencil and paper. Some of you young guys out there ought to be able to do it in a flash. Give you something to do beside think up your next troll fart.
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For a storm who can't maintain a full eyewall, I am in awe of Irene...
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Quoting hamla:
tornado watch just issued

patrap u da man


HPC and the Boyz are on it well seems
Member Since: July 3, 2005 Posts: 426 Comments: 128654
Quoting presslord:
Do women really think that looks good?!


sup...did you get the pic i sent ya?
Member Since: September 16, 2007 Posts: 0 Comments: 3650
737. 996tt
Quoting P451:


This is due to the absolute continuous sorties run through and around this storm. Throw in the mass weather balloon launch covering basically the eastern third of the US mainland and you have tons of great data for the models to crunch.





Yeah, they take it seriously when heading toward DC and NYC. We don't get near that servicing when entering the GOM toward us.

I totally get it though. Just shows what can be done when heightened scrutiny arises.
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Quoting weatherwart:


Your graphic is showing up as a big DISABLED BOX. You can see it. Everyone else sees the big black & white box.


I noticed I wonder why. Anyway I guess I'll install the software they reccomend and repost later.
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This is cool! Reminds me of when she had an eye. Wouldn't be surprised if she surprised everyone and sprouted a new one.

"Irene: From tropical storm to hurricane":

Link
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# 725

I'd modify that or you'll be on a permanent wu-cation

Member Since: July 3, 2005 Posts: 426 Comments: 128654
http://l.yimg.com/bt/api/res/1.2/t4bTtAb9Fn0Talo_zh MhHw--/YXBwaWQ9eW5ld3M7Zmk9aW5zZXQ7aD00OTU7cT04NTt 3PTYzMA--/http://media.zenfs.com/en_us/News/ap_web feeds/cd2a603b170ce713f60e6a7067002eb9.jpg
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junky...while I wouldn't disagree with that...I also probably wouldn't leave that up too long ;-)
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Quoting Levi32:
We've got to appreciate the outflow that is sustaining Irene as well. I mean look at the satellite loops - an 85kt outflow stream to the east of the storm, flowing south. That's amazing.


Irene's outflow coverage is ginormous. Just look at that image you posted.
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730. 996tt
Quoting aislinnpaps:
TWC is talking to Mark Potter from Nag's Head and he is saying about how many are not leaving. I think we may see deaths that weren't necessary before this is all over.


I hope not, but I don't get that sinking feeling I did when Ike was approaching and people were not leaving. I have been through canes before, including a direct hit by Ivan, and my rule of thumb is I stay unless 4 or 5. Cat 3 depends on track. I also live 10 stories up in a hurricane proof cement and steel structure though its right on the water. I did lose a stilt beach house in Navarre during Ivan. The entire house was washed into the sound on the other side, but I knew not to be there . . .
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729. hamla
tornado watch just issued

patrap u da man
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Quoting K8eCane:

nope thats not hurricane force...no hurricane force here that i can tell


you are aware the storm is still quite a bit to the south right?
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Quoting CaneHunter031472:
Talking about long range predictions here we go GOMEX IS next.

GFS 18Z T=384hrs




Your graphic is showing up as a big DISABLED BOX. You can see it. Everyone else sees the big black & white box.
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We've got to appreciate the outflow that is sustaining Irene as well. I mean look at the satellite loops - an 85kt outflow stream to the east of the storm, flowing south. That's amazing.

Member Since: November 24, 2005 Posts: 635 Comments: 26654
4200 on Folly Beach were without power all day...a 65mph gust knocked down a power pole.....and the repair guys in the buckets were having an interesting time up there in the breeze gettin' it all put back together
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Quoting Swpepper:


The vast majority of people not leaving Nags Head or the OBX in general are the residents, most of whom have weathered these storms multiple times.

Not to sound harsh, but it's the TOURISTS that evacuations are for. When you've got Joe Shmoe from Colorado who's never been in a hurricane in his life standing on his rental property balcony with a webcam, that's when death and injury occurs. I'd personally trust the judgement of a Nags Head resident of 40 years. Heck, around here we (jokingly) say that if the locals leave, it's time to run for the hills, because it's the end of the world.
There was a report I saw today on CNN that said that some of the older locals, who had rode out every storm for the last 40 years, were leaving for this one. Because of the direction and water rise from both sides. It was something that worried the real old-timers.
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Talking about long range predictions here we go GOMEX IS next.

GFS 18Z T=384hrs


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Quoting presslord:
Do women really think that looks good?!


Oh hell no.
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MIAMI (AP) — Forecasters say Hurricane Irene off the coast of North Carolina is still packing 100 mph winds and turning toward the north-northeast.

Tropical storm conditions are spreading all over southeastern North Carolina Friday night. The storm's main thrust is supposed to hit the Carolina coast early Saturday.

The National Hurricane Center is saying its biggest concern is storm surge of 6 to 11 feet along the coast of North Carolina. That is possible at Ablemarle and Pamlico Sounds.

A sustained wind of 50 mph was measured at Wrightsville Beach, N.C., along the coast.
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6,000 People in Wilmington without power..

Link
Member Since: August 19, 2006 Posts: 13 Comments: 15666
Quoting BahaHurican:
A lot of rain damage in PR, a lot of wind damage here - is Irene getting ready to complete the hurricane trifecta with serious surge damage in her third landfall?


Hopefully not, a diptych image of hurricane damage is plenty enough as it is.
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Do women really think that looks good?!
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712. Gorty
Quoting AllStar17:
Gorty:

Well, the farther east Irene goes....it would seem the weaker the winds would be in the W. Massachusetts area. I'm certainly rooting for Irene to go east, east, east!


Maybe the hurricane winds I won't get. But the local guys are getting a consensus that I will see just under hurricane force gusts.
Member Since: November 8, 2008 Posts: 12 Comments: 1058
Once the surge inundates,,above ones ability to remain higher,,well...one may have a difficult time surviving the Surge and winds.

Mr Guerra explains it well during the last min of this one from 6 years ago Monday.

Video taken by Guerra Family during/after Hurricane Katrina. Chalmette, La.


Member Since: July 3, 2005 Posts: 426 Comments: 128654
Quoting ncstorm:


I think it was a voluntary evacuation so I am pretty sure people are there..


Wow. That much water this early on, not a good sign.
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Quoting Dennis8:


8:00 PM 73.4 °F - 71.6 °F 94% 29.50 in 3.0 mi NNE 25.3 mph 38.0 mph 0.05 in Rain Heavy Rain

WILIMINGTON
nope thats not hurricane force...no hurricane force here that i can tell
Member Since: April 26, 2006 Posts: 5 Comments: 3190



Spanish Moss.
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Joe B. was buff! lol!
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I'm just amazed at how accurate the models have been as far as track is concerned. Also the fact that his monster was predicted 300 and so hours before it happened is also amazing. I'm glad the system is steadily weakenong, but It does not mean that it ia not dangerous anymore.
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705. zingo
Quoting KeyWestwx:
Zingo! Did u create this storm just to send it to your mother-in-laws house?!
I'm not saying right now. I kinda got side tracked with PressLords recent post. Joe looks good!! LOL
Member Since: September 1, 2008 Posts: 0 Comments: 17
Quoting weatherwart:


Are people staying out on that island or did most evacuate?


I think it was a voluntary evacuation so I am pretty sure people are there..
Member Since: August 19, 2006 Posts: 13 Comments: 15666
Quoting Patrap:
Note the Shear Markers on the Northern Semi Circle coming ashore,,expect a SPC Tornado Watch Box to be issued soon.



12z sounding for MHX shows a particularly unstable airmass too. That area in SE and S central NC is ripe for these rainbands to produce embedded rotating storms.
Member Since: September 24, 2005 Posts: 33 Comments: 9265

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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.