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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Is it me? Or did this blog go to hell, right about the time school lets out?
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If you look at this image you see the last four frames where new convection gets shut down, and a new piece of dry air is getting sucked in:



There is a new image coming out in the next 2 or three minutes, when it comes out it will have the URL:

http://rammb.cira.colostate.edu/ramsdis/online/im ages/tropical/214.jpg

After that, the next image in 30 minutes will be:

http://rammb.cira.colostate.edu/ramsdis/online/im ages/tropical/215.jpg

then it goes to 216, then back to 205 (for a total of 12 images).

If you see a really bright 215.jpg or 216.jpg image with lots of development, you are seeing the state of the storm 6 hours ago. keep hitting F5 until the new image comes out.
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BREAKING NEWS:
Hurricane Irene continues its churn toward the U.S. East Coast, and all indications are this storm will be, as President Obama said, "historic." Here are some events that weather experts say could develop over the next 48 hours:
-- Irene is bringing gusty winds, heavy rain and dangerous surf to the South Carolina coast today.
-- North Carolina will be pounded by Irene’s forces Friday night and Saturday.
-- Irene will head north Sunday, hitting a large swath from Virginia to Maine.
-- Major metro areas of Philadelphia, New York and Boston should brace for possible widespread damage, including major flooding, as Irene hits Sunday.
-- The strongest of Irene’s power will be to the east of its center.
-- Widespread power outages are expected over a large section of the Northeast.
-- New York’s metro transit system will be shut down at noon Saturday.
-- East Coast travel will be severely disrupted starting tonight. Hundreds of flights and Amtrak train lines have been canceled.
Member Since: August 28, 2006 Posts: 6 Comments: 2895
A new one to watch. 850 miles northeast of the Lesser Antilles, 1,600 miles east of Miami, 2,000 miles west-northwest of Cape Verde, and 700 miles east-southeast of Bermuda.:

BEGIN
NHC_ATCF
invest_al912011.invest
FSTDA
R
U
040
010
0000
201108261921
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 91, 2011, DB, O, 2011082618, 9999999999, , , , , , METWATCH, , AL912011
AL, 91, 2011082518, , BEST, 0, 274N, 544W, 30, 1018, DB, 0, , 0, 0, 0, 0,
AL, 91, 2011082606, , BEST, 0, 274N, 578W, 30, 1018, DB, 0, , 0, 0, 0, 0,
AL, 91, 2011082612, , BEST, 0, 274N, 590W, 30, 1017, LO, 0, , 0, 0, 0, 0,
AL, 91, 2011082618, , BEST, 0, 274N, 602W, 30, 1015, LO, 34, NEQ, 0, 0, 0, 0, 1017, 100, 25, 0, 0, L, 0, , 0, 0, INVEST, S,
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Quoting HCW:
TWC just said that it's the storm of  your lifetime if you are in the NE


They are absolutely correct! bbl
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Quoting ecupirate:


Thats all total BS and you know it. Points 1-3 are out-right lies and this is not Ike and not near Ike.

Just because YOU want a catasrophic event in the NE doesn't mean it will happen.

Look at this satelite loop and tell me its not weakening and struggling with dry air!

Link


None of that is lies. You need to stop trying to be the big clever person who knows better.
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Quoting TropicalAnalystwx13:
Blog is so much better with all those people on ignore..You should try it.

---

So Levi, this weakening was predicted by the models the whole time?


I didn't notice it until this morning. I usually pay very little attention to the intensity models. I was curious whether the GFDL picked up on the current weakening, and it did.
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870. TX2FL
I've come to the conclusion that the Local NWS which is out of Binghamton, NY in my area is useless. They are calling for 25 MPH winds with gusts to 30 in my area, meanwhile NHC and all models would indicate 45 MPH sustained with gusts to 60-70. SMH....
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Quoting MrstormX:


I'm living in a fantasy for saying that Bush and Reagan were on working vacations at their ranches, that is my historical interpretation so deal with it. And yes...Irene is moving pretty much due North.


Who cares about any of those fat cats.
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868. HCW
TWC just said that it's the storm of  your lifetime if you are in the NE
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Let's hope the models are wrong about Irene trying to intensify in 12-24 hours. An intensifying storm approaching land can cause more damage. Ex: Andrew.

Just ask the Bahamas....
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na na na na
na na na na
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864. hamla
i rode out katrina in lacombe la. and that was
the biggest mistake i have made in my life
when they say GO GO


'>Quoting carpentergrl:
I check here regularly during hurricane season and follow this and Levi's blogs during all active systems no matter where they are. I find the comments on Dr. Master's blog educational even some of the misinformation since I tend to look up much of what is being talked about on other sources offsite.

BTW, I live in SE Louisiana. I live north of the areas that received water damage from Katrina, but not far enough north to have avoided the wind. This area was without power for nearly 3 weeks: Their were over 20 trees down on our 7 acres. Once roads opened our local gasoline supply was quickly exhausted and people had to drive an hour NW to find fuel.

Interesting point about storm surge: Although N.O. was the focus of the flooding here (coastal MS took the worst actual surge), the Northshore area of Lake Ponchartrain took a lot of water. The bayous and rivers flooded well inland and overtook several areas, like Lacombe. In one particular area in Slidell, water reached 12' deep in the sub-division where I was trim carpenter. The land this sub-division was built on had never had any recordable flooding....ever.
Member Since: August 29, 2008 Posts: 0 Comments: 166
Quoting leftlink:


yes, in the SE corner of Irene's circulation where it meets the Bermuda high, looks like some kinda spin.
virgin of irene?? mind filling in a noob
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Member Since: August 2, 2010 Posts: 21 Comments: 9737
Quoting TropicalAnalystwx13:


FINALLY! SOMEBODY WITH COMMON SENSE!!!

Please stop with the scare capitals. Calm reason is what we want.
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Quoting GayWithFatalDisease:
My sources tell me Irene will be downgraded to 85mph at 5pm. No joke. True


You're sources are completely innaccurate and ur giving people the wrong info, thus you are risking lives because if they are not taking this seriously they have a good chance of getting killed. I gotta go now, not gonna deal with the bs on here. I'll be back later peeps.
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Irene is definitely looking less impressive on MIMIC, eye is falling apart in a huff. However the circulation is still super big, and that should help maintain hurricane status up to NC landfall. Not sure what will happen after that.

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Link
Member Since: July 6, 2010 Posts: 113 Comments: 31555
Irene pulling a Charley and wobbling away from the forecast points...
Member Since: August 28, 2006 Posts: 6 Comments: 2895
Tigger? What's the latest down there? Heard something about a surfer on IOP?
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Blog is so much better with all those people on ignore..You should try it.

---

So Levi, this weakening was predicted by the models the whole time?
Member Since: July 6, 2010 Posts: 113 Comments: 31555
Irene still remains a very large threat! However, this satellite image makes Irene look ragged right now as it struggles with dry air. I'm not saying it won't come back later. I'm just stating what I see....and that is a less organized storm than yesterday.
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Quoting SeniorPoppy:


Keep doom casting if that makes you feel better.


Not DOOM casting, being prepared. I barely survived with my life in Katrina. Was airlifted from a helicopter from my home. Do not talk to me about underestimating a storm or being prepared and warned.
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Quoting ConnecticutWXGuy:
So here's a question for you whiners about "oh the media over-hyped the storm."

What is better? over-hyping, or under-hyping? Because unless you can make perfect forecast without any chance of being wrong... one or the other is always going to happen. Do you suggest that the media takes the current forecasts and downplays them? Because as much as I disagree with a lot of what the media does, they certainly have not "up-played" this storm and its potential all that much at all. So if what forecasters and the media have been saying is "over-hyping" Irene... then I can only assume what you desire is for them to downplay every forecast until a hurricane is virtually on-top of any given forecast landfall.


Well said! I don't envy the media at all! In these situations. Damned if they do! Damned if they don't
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Tazmanian4


imposter
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838. 7544
i think today will be good time to reair the program it could happen tomorow for the nyc area to give the peeps there a idea of what they are going to get
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Quoting TropicalAnalystwx13:


FINALLY! SOMEBODY WITH COMMON SENSE!!!


Intensification is the hardest to forecast.
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Quoting MrstormX:


I'm living is a fantasy saying that Bush and Reagan were on working vacations at their ranches, that is my historical interpretation so deal with it. And yes...Irene is moving pretty much due North.
working on clearing timber for the American people?
:P
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I doubt Irene is ever going to clear out another eye, it will have a cloudy but distinguishable center up until its NC landfall. After that point it will start to look ragged, and as it gets well N it will start looking like a giant gale storm. (That is how I see it going down)
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looking at these posts makes it look like there is nothing to worry about. Idiots

later
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Quoting SeniorPoppy:
Lol the doom and gloom forecasts were hilarious on the weather channel this week. More than likely, Irene will be a classic sheared mess when it gets into the mid Atlantic region and northeast.


Every time Stephine Abrams spoke she used the word

"CATASTROPHIC"!!!!!
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I live in Massachusetts and the folks I've seen today are having trouble getting what the storm will do. The last couple of hurricanes petered out as they approached New England and we have hurricanes so rarely that "Category 1" or "Category 2" have no visceral meaning.

I think a forecast that said something like "maximum of 85 mph winds for 4 - 6 hours" would be far more understandable in regions where hurricanes are relatively rare and might speed up preparations.
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Quoting CapnK:
First rainband in Georgetown, SC this AM.




Full size image (800pix wide) at my WU blog.


yeah...we were hit with some in charleston...im in town so didn't get any good pics like that...but saw the black flying at me when i was outside...it was wicked to say the least...not hitting us head on but the Hugo flashbacks were well...yeah...
Member Since: September 16, 2007 Posts: 0 Comments: 3650

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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.