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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atmosweather:

I must say you are providing some very thorough and easy-to-understand analyses. Thank you!
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Quoting mydiapersarefull:
From my WB bunker, I can confirm that Aaron Rodgers is looking pretty sharp...











I concur...born a cheesehead
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Quoting 900MB:
Okay, I downloaded Google Earth, Google Chrome, etc...Now how do I get the hurricane hunter recon again?
Thanks!!!

Right click on the link to the .kmz file and save it to your hard drive. Someplace easy like "My Documents". Then click on it and let your computer choose Google Earth to open it (or open Google Earth and click "File" and "Open" and select the .kmz file). You should have all the Hurricane Hunter info your heart desires. Click on the "Weather" tab and you can turn on the satellite or radar too....
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Norcross stated she' larger than Ike.
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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.


Hi. First time poster longtime lurker, and I don't want to start with an argument, but my sister is an EMT in a coastal NC County, and attitudes like the one above endanger her life. Mandatory evacuation means get the hell out. Not get out if you feel like it. Not get out if you're not an old timer who thinks he knows more than the actual meteorologists. Get out. And if you don't, you shouldn't expect emergency workers to do more than fish your waterlogged corpse out of the bay.
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Member Since: July 3, 2005 Posts: 426 Comments: 128609
Quoting weatherwart:


I heard that on TWC, yeah. Closing at noon tomorrow. Then Cantore was talking about the surge at Battery Park. It could be a real mess.

Got it from more official sources, but same same.

Surge is a real concern here, even if the storm weakens because of the size of windfield and the volume of water that is moving.

Another thing...Many of the areas in the cone have had a lot of rain lately and saturated ground. I had the same thing here with Jeanne. Huge pines that had seen a lot of canes came down due more to lack of grip than the force of the wind. I'm expecting to see a lot of that with this storm.
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Quoting j2008:

95 to 100Knts is 110-115MPH, that would be an increase.


That's at flight level. Taking an 80% reduction (could be more like 70-75% since Irene's energy is spread out over such a large area)...this yields 80 kts at best at the surface. They likely didn't sample the strongest winds so she most likely remains a 100 mph Category 2 storm.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting drg0dOwnCountry:
Science is not about politics.


I really wonder if they teach science in some parts of our country anymore.
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Wind are gusting strong now in Wilmington. Heavy rain band coming for us hope it's not the one to deliver the knockout blow as far as electricity is concerned
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From my WB bunker, I can confirm that Aaron Rodgers is looking pretty sharp...









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Quoting TropicalAnalystwx13:
Question: How much worse should conditions get here overnight and tomorrow?
Link
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Quoting 996tt:


I am real close to you. We are staying in Presidio Yacht Club right now, but also have a house in 30a, Rosemary Beach.


wow nice places...We built a rental at Frangista. I currently am in FWB.
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838. 996tt
Quoting JamesSA:

Where do you live?


I got denied many times trying to paddle out today in Cocoa Beach. I was watching guys on cam in Delray yesterday with amazement.
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Quoting 996tt:


Get it, but F2 and F3 tornados have hit down town high rises in Atlanta and Dallas and no real loss of life. These strikes were much more intense and worse than cat 1 winds and perhaps TS winds by the time it even gets there. Again, if he is going to scare everyone, where does he expect them to go.

If they were intellectually honest, they would mention that high rises have sustained direct hits by tornadoes and survived. They just conveniently leave out objective details and play on the subjective.


Why is it so freaking bad to over prepare for this storm? I keep seeing your posts downplaying this: Cat 1 only, media over hype blah blah blah. It may very well be over hyped, but would you rather them treat it like yourself and then potentially get bitten in the ass by this storm? I'd say the dozens of people who died on Galveston Island would've rather had this over hype. My god man 8 people have confirmed to have been killed by this storm already and 1.5 B worth of damage has been done. Treat this storm as a serious threat and nothing can go wrong, treat it as no big deal and you can get injured or worse. Your choice, but I'd take over preparing.
Member Since: October 16, 2008 Posts: 0 Comments: 544
Quoting atmosweather:
Seems like RECON still cannot find any flight level winds more than 95-100 kts. Heights have not dropped in the center and the pressure remains right around 950 mb, so although she appears to be ever so slightly more organized in satellite imagery, that is not being reflected in the actual data so far. We'll see what happens tonight as she has 6-12 hours (at best) left for any restrengthening to happen.


6-12 hours is a long time in Hurricane hours. I have been through 12 TS/ hurricanes and seen many a storm strengthen in the last 3 hours when they were NOT forecast too. 1970 Celia 80 mph storm ended up blowing the airport anemometer off at 161 mph..this lead me to my interest in wx an to getting my meteorology degree years later.
Member Since: August 15, 2008 Posts: 0 Comments: 446
Quoting 996tt:


Get it, but F2 and F3 tornados have hit down town high rises in Atlanta and Dallas and no real loss of life. These strikes were much more intense and worse than cat 1 winds and perhaps TS winds by the time it even gets there. Again, if he is going to scare everyone, where does he expect them to go.

If they were intellectually honest, they would mention that high rises have sustained direct hits by tornadoes and survived. They just conveniently leave out objective details and play on the subjective.


As I heard it, their point of stress for evacuating the high rises in Zone A wasn't due to risk of injury by living on the higher floors. Instead it was the risk of being isolated in an emergency where first responders wouldn't be able to reach them during an emergency due to flooding at the lower / street levels of the high rise. Personally, I think this is a reasonable justification for stressing the need to evacuate. Water enters the lower levels of a high rise, sparks a fire from interaction with an electrical panel and everyone who decided to ride it out is stuck on the higher levels with an out of control fire below them.
Member Since: September 2, 2008 Posts: 0 Comments: 62
Quoting TropicalAnalystwx13:
Question: How much worse should conditions get here overnight and tomorrow?


You should begin to see steadier tropical storm force sustained winds up to 50-60 mph with the chance of hurricane force gusts later tonight and tomorrow morning, then decreasing to 35-45 mph with higher gusts into tomorrow afternoon as she passes your area. Bear in mind there is the potential for isolated tornadoes tonight as her stronger rainbands move in and warm the low level atmosphere further.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
TWC still not in storm alert.
Making the last preparations here in SW CT.

by the way look how big Talas is
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Quoting presslord:
pretty much over here Junky....'cept for some flooding


How much rain and/or surge did you get?
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831. j2008
Quoting atmosweather:
Seems like RECON still cannot find any flight level winds more than 95-100 kts. Heights have not dropped in the center and the pressure remains right around 950 mb, so although she appears to be ever so slightly more organized in satellite imagery, that is not being reflected in the actual data so far. We'll see what happens tonight as she has 6-12 hours (at best) left for any restrengthening to happen.

95 to 100Knts is 110-115MPH, that would be an increase.
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830. 996tt
Quoting JGreco:



I rode out Ivan too in Mary Esther past hurlburt. That was nerve racking:0 Especially with the 115mph sustained and gusts into the 130's I felt during that storm:0


I am real close to you. We are staying in Presidio Yacht Club right now, but also have a house in 30a, Rosemary Beach.
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829. 900MB
Quoting P451:


Start here: http://tropicalatlantic.com/recon/

Download the google earth file. Double click on it and it will install to google earth. Then you'll see a drop down menu appear on your left panel with the recon.



Thanks. Wow, that is complex, but very cool!
Member Since: June 11, 2006 Posts: 0 Comments: 684
Time: 00:34:00Z
Coordinates: 32.2667N 77.0W
Acft. Static Air Press: 696.1 mb (~ 20.56 inHg)
Acft. Geopotential Hgt: 2,715 meters (~ 8,907 feet)
Extrap. Sfc. Press: 949.6 mb (~ 28.04 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 2° at 5 knots (From the N at ~ 5.8 mph)
Air Temp: 14.9°C (~ 58.8°F)
Dew Pt: 11.0°C (~ 51.8°F)
Peak (10s) Flt. Lvl. Wind: 6 knots (~ 6.9 mph)
SFMR Peak (10s) Sfc. Wind: 11 knots* (~ 12.6 mph*)
SFMR Rain Rate: 0 mm/hr* (~ 0 in/hr*)
(*) Denotes suspect data
Member Since: September 8, 2005 Posts: 0 Comments: 3805
Quoting RobDaHood:
From what I heard today, they are expecting to have problems just from the rain. The pumps won't be able to keep up even without surge. That is why they are planning to shut down.


My brother is at Ft. Drum (NY..upstate), they are preparing for TS force winds and a lot of rain. He said NY has gotten a lot of rain lately, too. I see what you mean.
Member Since: August 16, 2007 Posts: 1 Comments: 2350
Hi everyone! It's been pretty bad the last three hours here in Kure Beach, NC. The gusts have been picking up in intensity and frequency and the last time I checked, if you wanted to walk to the beach, you'd have to find another location where the water hadn't come up against the dunes. Waiting for the worst. Anybody got a guess on what the highest winds will be here? Isn't it weird how I live on a barrier island, still have power, but places inland in New Hanover county have been without power for several hours.
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Quoting breald:


Oh that is so sad. :(


Very very sad..what we are really talking about.. IRENE..A KILLER.
Member Since: August 15, 2008 Posts: 0 Comments: 446
Quoting RobDaHood:
From what I heard today, they are expecting to have problems just from the rain. The pumps won't be able to keep up even without surge. That is why they are planning to shut down.


I heard that on TWC, yeah. Closing at noon tomorrow. Then Cantore was talking about the surge at Battery Park. It could be a real mess.
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Quoting JamesSA:

Where do you live?


Folly Beach SC
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Seems like RECON still cannot find any flight level winds more than 95-100 kts. Heights have not dropped in the center and the pressure remains right around 950 mb, so although she appears to be ever so slightly more organized in satellite imagery, that is not being reflected in the actual data so far. We'll see what happens tonight as she has 6-12 hours (at best) left for any restrengthening to happen.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting Patrap:


It has quite the OMG factor and is one to share.

That video makes me tear up..can't watch it anymore...just happy I live in central texas. Just knowing people had to hack through their attics to survive...frightening isn't a strong enough word.
Member Since: August 16, 2007 Posts: 1 Comments: 2350
Quoting surferfb:


Very sorry to hear. I grew up and my parents still live on 5th East.


there was a kite boarder missing most of the day...started out Sullivan't island/IOP... wonder if it was him since tide just came in here (6:30pm high)
Member Since: September 16, 2007 Posts: 0 Comments: 3650
Quoting 996tt:
Everyone is taking prudent safety measures. That's great. Okay, dude is trying to scare 90 percent of the population in NYC by telling them to get out of their high rise buildings. Seriously, those things could take a F2 o3 tornado hit. Is he trying to take about venturi effect? Everyone living in a big city knows this, but where does he expect all of these people living in high rise buildings to go?
What dude is this. I would bet those buildings have had more than this storm will dish up. Not downplaying storm, just believe that there have been NorEasterners with bigger wind punch than this will be. Storm Surge off the rivers may be another thing.
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Question: How much worse should conditions get here overnight and tomorrow?
Member Since: July 6, 2010 Posts: 113 Comments: 32230
Quoting presslord:


they just left with a body they fished out right across from my house @ 4East

Where do you live?
Member Since: August 17, 2009 Posts: 0 Comments: 579
8:37 PM 73.4 °F - 71.6 °F 94% 29.48 in 1.8 mi NNE 33.4 mph 42.6 mph 0.33 in Rain Heavy Rain

Wilmington, NC
Member Since: August 15, 2008 Posts: 0 Comments: 446
Fellow Wilmington residents how we holding up? Power flickering but so far so good for me. I was at wrightsville at high tide and the ocean was CRAZY... don't think the island will make it unscathed next high tide at 6am, also when Irene makes her closest approach, I hope everyone there leaves , that island is in danger tonite . Only 1hr15m til they close the bridge
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What is the wind shear forecast up until landfall in the out banks?

Thnks
Patrick
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Quoting 996tt:


Get it, but F2 and F3 tornados have hit down town high rises in Atlanta and Dallas and no real loss of life. These strikes were much more intense and worse than cat 1 winds and perhaps TS winds by the time it even gets there. Again, if he is going to scare everyone, where does he expect them to go.

If they were intellectually honest, they would mention that high rises have sustained direct hits by tornadoes and survived. They just conveniently leave out objective details and play on the subjective.

Well, tornadoes occupy a very small area, and do not last for long. Hurricanes cover hundreds of miles, and last for hours and hours in a location.
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Quoting weatherwart:
I'm not familiar with New York, but if they get a 4-8ft storm surge in the city, how do they keep the water out of the subway system?
From what I heard today, they are expecting to have problems just from the rain. The pumps won't be able to keep up even without surge. That is why they are planning to shut down.
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Quoting avthunder:
Wow - that was amazing. Should be mandatory viewing for everyone who refuses to leave an evacuation area.


It has quite the OMG factor and is one to share.
Member Since: July 3, 2005 Posts: 426 Comments: 128609
Quoting presslord:


they just left with a body they fished out right across from my house @ 4East


Very sorry to hear. I grew up and my parents still live on 5th East.
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After doing a rough copy and paste of Irene and pasting her in Europe, she would fill up the entire "thicker" section of Europe aka western Europe.... she is about 4/9ths the width of Europe from west to east... so I'd say after accounting for Europe occupying less land at its Eastern end Irene is roughly half the size of Europe... correction her CIRCULATION is... where precip and rain is falling, probably more like 30% to 40%.
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Right, I'm off to bed. Anybody in the way of this thing, take care. Back in 6 or 7 hours.
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Quoting 996tt:


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 . . .



I rode out Ivan too in Mary Esther past hurlburt. That was nerve racking:0 Especially with the 115mph sustained and gusts into the 130's I felt during that storm:0
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Quoting presslord:


they just left with a body they fished out right across from my house @ 4East


Real shame. :(
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Quoting presslord:


they just left with a body they fished out right across from my house @ 4East
Oh, that's horrifying. I'm so sorry to hear that.
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pretty much over here Junky....'cept for some flooding
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Wilmington animated, WunderMap®
Member Since: July 3, 2005 Posts: 426 Comments: 128609

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.