Irene's eyewall collapses; further intensification unlikely

By: Dr. Jeff Masters , 3:14 PM GMT on August 26, 2011

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Satellite data and measurements from the Hurricane Hunters show that Irene is weakening. A 9:21 am EDT center fix by an Air Force Reserve aircraft found that Irene's eyewall had collapsed, and the central pressure had risen to 946 mb from a low of 942 mb this morning. The highest winds measured at their flight level of 10,000 feet were 125 mph, which would normally support classifying Irene as a Category 3 hurricane with 115 mph winds. However, these winds were not mixing down to the surface in the way we typically see with hurricanes, and the strongest surface winds seen by the aircraft with their SFMR instrument were just 90 mph in the storm's northeast eyewall. Assuming the aircraft missed sampling the strongest winds of the hurricane, it's a good guess that Irene is a mid-strength Category 2 hurricane with 100 mph winds. Satellite imagery shows a distinctly lopsided appearance to Irene's cloud pattern, with not much heavy thunderstorm activity on the southwest side. This is due to moderate wind shear of 10 - 20 knots due to upper-level winds out of the southwest. This shear is disrupting Irene's circulation and has cut off upper-level outflow along the south side of the hurricane. No eye is visible in satellite loops, but the storm's size is certainly impressive. Long range radar out of Wlimington, North Carolina, shows that the outermost spiral bands from Irene are now beginning to come ashore along the South Carolina/North Carolina border. Winds at buoy 41004 100 miles offshore from Charleston, SC increased to 36 mph as of 10 am, with significant wave heights of 18 feet.


Figure 1. Distribution of Irene's wind field at 9:30 am EDT Friday August 26, 2011, as observed by the Hurricane Hunters and buoys. The right front quadrant of the hurricane had about 90% of the storm's hurricane-force winds (yellow and warmer colors, bounded by the heavy black line between the "50" and "60" knot thin black lines.) Tropical storm-force winds (heavy black like bounding the light blue area) extended out 290 miles from the center of Irene. Image credit: NOAA/AOML/HRD.

Forecast and storm surge potential for Irene
With its eyewall collapsed and just 24 more hours over water before landfall, it is unlikely Irene will have time to build a new eyewall and intensify. The storm is too large to weaken quickly, and the best forecast is that Irene will be a Category 2 hurricane at landfall in North Carolina on Saturday, and a rapidly weakening Category 1 hurricane at its second landfall in New England on Sunday. However, since Irene is such a huge storm--tropical storm force winds extend out up to 290 miles from the center--it has set a massive amount of the ocean's surface in motion, which will cause a much larger storm surge than the winds would suggest. At 9:30am EDT this morning, a wind analysis from NOAA/HRD (Figure 1) indicated that the potential storm surge damage from Irene rated a 5.1 on a scale of 0 to 6. This is equivalent to the storm surge a typical Category 4 hurricane would have. While this damage potential should gradually decline as Irene moves northwards and weakens, we can still expect a storm surge one full Saffir-Simpson Category higher than Irene's winds. Since tides are at their highest levels of the month this weekend due to the new moon, storm surge flooding will be at a maximum during the high tidal cycles that will occur at 8 pm Saturday night and 8 am Sunday morning. Wherever Irene happens to be at those times the storm surge damage potential will be maximized. A surge rivaling that experienced during Hurricane Isabel in 2003 is likely in northern NC, southern Maryland, and up Chesapeake Bay on Saturday night. Coastal New England from New York City to Massachusetts may also see storm surges characteristic of a Category 1 hurricane during Sunday morning's high tide, even if Irene has weakened to a tropical storm. I continue to give a 20% chance that a storm surge high enough to over-top the Manhattan flood walls and swamp the New York City subway system will occur on Sunday.

Wind damage
I don't think Irene is going to do a lot of wind damage to the mid-Atlantic states, since the eye of the storm will be just offshore, and the I-95 corridor from Virginia to New Jersey will be on the weak (left) side of the hurricane. The current wind distribution of Irene (Figure 1) shows almost all of the hurricane's winds are on the right side of the storm, and by the time the storm reaches Virginia, there will be likely be no hurricane-force winds on the left side of Irene. Sustained winds should stay below 74 mph (hurricane force), and wind damage will be similar to that wrought be some of the strongest Nor'easters of the past 20 years, from Virginia northwards to New York City. Since Irene will be steadily weakening as it approaches its second landfall on Long Island, I give a 50% chance that no mainland U.S. surface station in New England will record sustained hurricane-force winds. I do think it likely that one or more of the offshore islands--Block Island, Nantucket, and Marthas Vinyard--will get Category 1 hurricane winds. Though the wind damage to buildings will be similar to what the Northeast has seen during some of the more severe nor'easters of the past 20 years, tree damage will be much worse. The trees are in full leaf during hurricane season, and catch the wind much more readily than during the winter. Tree damage will very heavy, and we can expect trees in regions with saturated soils will fall over in high winds onto power lines. Irene is likely to cause one of the top-five most widespread power outages in American history from a storm. The record power outage from a Northeast storm was probably the ten million people that lost power during the great Blizzard of 1993. I don't think Irene's power outages will be quite that extensive, but several million people will likely lose power.

Irene likely to bring destructive fresh water flooding
In addition to storm surge, flash flooding and river flooding from Irene's torrential rains are the main threats. The hurricane is expected to bring rains in excess of 8" to a 100-mile-wide swath from Eastern North Carolina northwards along the coast, through New York City. The danger of fresh water flooding is greatest in northern New Jersey, Southeast Pennsylvania, and Southeast New York, where the soils are saturated from heavy August rains that were among the heaviest on record. New Jersey has had its 6th wettest August on record, with most of that rain falling in the past two weeks. Expect major river flooding throughout New Jersey the Delmarva Peninsula, and regions near New York City, as Irene's rains run off the saturated soils directly into the rivers. In general, the heaviest rains will fall along the west side of the hurricane's track, and the greatest wind damage will occur on the east side. I don't think flooding from heavy rains will be a huge concern in North Carolina, which is under moderate to severe drought. Irene's rains are likely to do some good in Southeast Virginia, where a fire triggered by lightning from a thunderstorm on August 4 sparked a fire in the Dismal Swamp that is burning out of control. Right now, it does not appear that tornadoes will be a major concern, but there will probably be a few weak tornadoes. Hurricane Bob of 1991, the last hurricane to affect New England, spawned six tornadoes, most of them weak F-0 and F-1 twisters.


Figure 2. Predicted rainfall for the 5-day period ending at 8 am EDT Wednesday August 31, as issued by NOAA/HPC.

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

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

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

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

Internet radio show on Irene at 4:30pm EDT
Wunderground meteorologists will be discussing Hurricane Irene on a special edition of our Internet radio show, the Daily Downpour, today (Friday) at 4:30pm EDT. Shaun Tanner , Tim Roche, Angela Fritz, and Rob Carver will there, and I will be available if my schedule permits. Listeners can email in or call in questions. The email address to ask questions is broadcast@wunderground.com.

Portlight mobilizes for Irene
The Bahamas have been hit hard by Irene, and unfortunately, it appears that the Northeast U.S. may have its share of hurricane victims before Irene finally dissipates. My favorite disaster relief charity, Portlight.org, is mobilizing to help, and has sent out their relief trailer and crew to North Carolina. Check out this blog to see what they're up to; donations are always needed.

Jeff Masters

Hurricane Irene's Wrath ! (MikeTheiss)
A shot of the Palm Trees at Nassau, Bahamas being thrashed by high winds during Irene's closest approach !
Hurricane Irene's Wrath !
Aftremath of Hurricane Irene in Nassau, Bahamas (ktbahamas)
Utility pole with street light snapped in half by Irene's winds on a busy street in New Providence.
Aftremath of Hurricane Irene in Nassau, Bahamas
Irene Response (presslord)
Portlight deploying to North Carolina
Irene Response

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Quoting Levi32:
Clearly a very unhealthy SW quad and an attempt at a double eyewall:



Based off that image I have a VERY difficult time believing Irene will even maintain her strength let only strengthen. It's entire southern half has been eroded. Those things don't fix themselves overnight. Even still massive windfield 75+ over a 150 mile area is still a very real threat to lives. Not too mention I am very curious to what type of surge we will see with this storm with its pressure being way down there around 950 mb range.
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All the birds in New York are gone. Its dead silent out here in Westchester county. Also why hasn't anyone boarded up their windows?
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Quoting Levi32:


Thanks. I don't see a live stream there, but maybe they'll have one up when landfall is occurring.


Yep, they always send reporters to the coast for these events.
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Quoting ncstorm:


by the time Irene gets here, it wont be a light on in wilmington..LOL


She's coming in soon.

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Quoting stormchaserDAZ:
virgin of irene?? mind filling in a noob


I had posted that if you looked at the rainbow loop in post 540, on the last frame there is what may appear to some as a face in the lower right of the frame.

That's all; sorry to take up bandwidth; just thought it was amusing.
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Quoting ncstorm:


by the time Irene gets here, it wont be a light on in wilmington..LOL


its gone up..

By 2:45 p.m. Friday, nearly 3,700 Progress Energy customers were already without power
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Quoting PrivateIdaho:
Cape Lookout NC...things are going to start going down hill here in a hurry.




can u find me one for the Chas area...press just called, still no power, wants updates...last i got on my phone was conditions for us to be worst from 3pm - 8pm tonight...tia and press thanks you too...already told him you were posting winds for us :)
Member Since: September 16, 2007 Posts: 0 Comments: 3650
Quoting Bluestorm5:
I'm REALLY frustrated with Weather Channel. North Carolina's coast should be in Catastrophic Threat as well for Wilmington to OBX. Storm surge will hit us hard...



I think catastrophic would be if Irene was a Cat 4 or Cat 5, not that damage won't be severe there.
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Taz-4 = No more!
Po-Po-Po-Poof
Enjoy the troll pit.
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Quoting TropicalAnalystwx13:


lol, it just started raining?
\

there is actually rather strong winds judging by the live video feeds showing these outer bands. It is more than just raining.
Member Since: November 17, 2010 Posts: 11 Comments: 527
Lights went out in Houston, Texas in Ike at 45 mph gust....
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Quoting ncstorm:


Really?


Yes.

Quoting AllStar17:


Do you rely on that graphic?


No.
Member Since: July 6, 2010 Posts: 113 Comments: 32080
Quoting wunderweatherman123:

compared to today in the morning does she look better?


Nope - worse.
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I'm REALLY frustrated with Weather Channel. North Carolina's coast should be in Catastrophic Threat as well for Wilmington to OBX. Storm surge will hit us hard...

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Quoting DontAnnoyMe:


WRAL should be a good one for NC.


Thanks. I don't see a live stream there, but maybe they'll have one up when landfall is occurring.
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Quoting Bluestorm5:
IT'S THE STORM SURGE AND FLOODING THAT IS A THREAT FOR NE, NOT WINDS.


That's true but a cat 1 storm surge is nothing compared to what they were calling for even last night.
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Quoting Levi32:
Clearly a very unhealthy SW quad and an attempt at a double eyewall:


compared to today in the morning does she look better?
Member Since: August 23, 2011 Posts: 0 Comments: 1724
Quoting Bluestorm5:
IT'S THE STORM SURGE AND FLOODING THAT IS A THREAT FOR NE, NOT WINDS.


Not true. Didn't you read Dr. M's blog?

"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. "
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957. Gorty
Quoting SeniorPoppy:



The fear mongering is in full swing.


Right, that means my NWS has me which is far from the coast in western Mass, has wind gusts to 80 mph and sustained winds increasing from 45-55 to 45-65 mph. But no, you are far more experienced than the people at my NWS...

-sarcasm-
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I wonder if the Hurricane warnings will be changed to Tropical storm warnings due to Irene's continued weakening trend..seems plausible
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Quoting Levi32:
Clearly a very unhealthy SW quad and an attempt at a double eyewall:



She is digesting a lot of dry air on the SW side. Looks to cut her in two
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Quoting Elena85Vet:
I posted this in earlier blogs.

For those questioning whether they should leave their homes.

If local officials are evacuating or suggesting evacuation from your area...GO!!

If you are near the coast below 25ft Mean Sea Level (MSL)...GO!!

If you are MILES inland, but in a flood zone near creeks or rivers...GO!!

The primary threat to life from Irene is going to be WATER. Both 'sea water' (within a few miles of the beach) and 'fresh water' heavy rain (inland near creeks and rivers).

Coastal Storm Surge refers to WATER LEVEL above mean sea level (MSL). There are waves to be added on top of that.

The unknown is NOT worth the RISK.


Winds from a strong CAT 2 or weak Cat 3 are NOT going to cause widespread 'catastrophic' structural damage to homes (ala Hurricane Andrew). Those winds will however knock out power and the ability of your municipality to pump water to your home for potentially a couple of weeks. Those winds will knock trees over (possibly onto your home), peal shingles from your roof, siding from your home, rip the cheaper steel sheds from their footings, cause projectiles to go airborne into windows. Anything that is not bolted down in your yard needs to be put away. Stay indoors.

Please be respectful of Emergency Personel before, during, and after the storm. They are only doing their jobs.


Edit: Even though the eyewall of Irene has collapsed and further intensification is unlikely, does not change the above information.


post of the day...add in, power outages, storm surge and flooding causes sewer backups...the raw sewage can and will contaminate EVERYTHING you own...it isn't just the wind...it is what is IN the winds...and Irene's winds may have diminished some, but the surge and the water/rain that is in her is still the original cat strength...it has to release at some point...the winds may have gone down but not the intensity
Member Since: September 16, 2007 Posts: 0 Comments: 3650
Quoting SeniorPoppy:



The fear mongering is in full swing.


Regardless of how great you are, and how you have the media completely cracked, it's better to have people prepared, and a bust of a storm, than have people unprepared and have a serious event with wide scale flooding.
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Quoting NICycloneChaser:


Wow, power starting to go out already? Only had the first edge of Irene.


by the time Irene gets here, it wont be a light on in wilmington..LOL
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The 12z Euro finally shows more realistic deepening to 943mb at landfall in NC, but the pressure is slow to rise as Irene moves up the mid-Atlantic states, still 954mb near the Jersey coast in 48 hours.

The reality here is that as long as Irene keeps her pressure under 960mb at landfall in NC, no matter what the winds are there, this is going to be an epic storm in the northeast United States. It's massive, and the storm surge won't be that much different if Irene is only a low-end Cat 2 in North Carolina. Her intensity in New England won't be much different either. It could be good news for North Carolina, but nothing has changed farther north.

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I think we all need to look at this again!!!
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Quoting TropicalAnalystwx13:
The Weather Channel is about to upgrade the threat level for parts of the Northeast to Catastrophic.


Do you rely on that graphic?
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Quoting overwash12:
100% should be at 115mph by 8 A.M. Sat. morning.


Tell me what the power ball numbers are going to be on Saturday. Please
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Quoting TropicalAnalystwx13:


lol, it just started raining?


LOL..I know right..
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Quoting ncstorm:
New Hanover County - Thousands without power around Wilmington
Published: Friday, August 26, 2011 at 8:35 a.m.
Last Modified: Friday, August 26, 2011 at 3:18 p.m.

About 2,600 people without power

UPDATE: About 2,600 Progress Energy customers were without power at about 2:45 p.m., according to the utility's website.

Multiple power failures are being reported in the Myrtle Grove area of New Hanover County and near the intersection of Wrightsville Avenue and Independence Boulevard.

The utility is assessing damage right now in several of the areas according to the company's site.

- From staff reports


Wow, power starting to go out already? Only had the first edge of Irene.
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944. HCW
91L


Member Since: August 10, 2002 Posts: 0 Comments: 1408
Why is the GFDL consistently the westernmost track?
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Quoting TropicalAnalystwx13:
The Weather Channel is about to upgrade the threat level for parts of the Northeast to Catastrophic.


Really?
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Quoting ncstorm:
New Hanover County - Thousands without power around Wilmington
Published: Friday, August 26, 2011 at 8:35 a.m.
Last Modified: Friday, August 26, 2011 at 3:18 p.m.

About 2,600 people without power

UPDATE: About 2,600 Progress Energy customers were without power at about 2:45 p.m., according to the utility's website.

Multiple power failures are being reported in the Myrtle Grove area of New Hanover County and near the intersection of Wrightsville Avenue and Independence Boulevard.

The utility is assessing damage right now in several of the areas according to the company's site.

- From staff reports


lol, it just started raining?
Member Since: July 6, 2010 Posts: 113 Comments: 32080
Quoting TropicalAnalystwx13:
The Weather Channel is about to upgrade the threat level for parts of the Northeast to Catastrophic.



The fear mongering is in full swing.
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Quoting Tazmanian4:
no i am real taz al so i this got bannded yesterday so i this new acount


the real taz knows how to speak English and spell.
Member Since: November 17, 2010 Posts: 11 Comments: 527
Quoting Levi32:
Does anyone know of any good live news streams, perhaps local ones on the east coast for Irene? Here in Fairbanks I have no TV and I'm going to miss seeing reporters from TWC and CNN in the storm. I want to know what's going on there.


WRAL should be a good one for NC.
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Quoting GayWithFatalDisease:


LOL, talk about ragged. LOL. NYC will see a thunderstorm. 40 MPH come Saturday night


Heavy rains too.
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Cape Lookout NC...things are going to start going down hill here in a hurry.


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Quoting SeniorPoppy:


A tropical storm. So overly dramatic. There will be some significant effects but that statement is over the top.
IT'S THE STORM SURGE AND FLOODING THAT IS A THREAT FOR NE, NOT WINDS.
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Due to the fact, that I cannot stop a hurricane, or escape it's consecuences; This would be my plan.
I would have a backup of money for such events as this one. Get all your necessary documents according to a pre elaborated plan and Take a vacation inland Conus. Leaving on time, drive with your family, (taking care, that you leave in a safe place the ones that would prefer to stay} going West to whatever city you want to explore and get to know. Staty in modest motel and visit museums, zoos or whatever are your likes... And sure, Remember to Have your insurance up to date...
At least in Conus, you can prepare on time and either bunker down or leave. Here I can only prepare and bunker down...
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New Hanover County - Thousands without power around Wilmington
Published: Friday, August 26, 2011 at 8:35 a.m.
Last Modified: Friday, August 26, 2011 at 3:18 p.m.

About 2,600 people without power

UPDATE: About 2,600 Progress Energy customers were without power at about 2:45 p.m., according to the utility's website.

Multiple power failures are being reported in the Myrtle Grove area of New Hanover County and near the intersection of Wrightsville Avenue and Independence Boulevard.

The utility is assessing damage right now in several of the areas according to the company's site.

- From staff reports
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The Weather Channel is about to upgrade the threat level for parts of the Northeast to Catastrophic.
Member Since: July 6, 2010 Posts: 113 Comments: 32080
929. Gorty
Wow me in western Mass! from nws:

Sunday: Tropical storm conditions possible. Showers. The rain could be heavy at times. High near 69. East wind 45 to 55 mph increasing to between 45 and 65 mph. Winds could gust as high as 80 mph. Chance of precipitation is 100%. New rainfall amounts in excess of 4 inches possible.

I did the bold parts.
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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.