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

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Quoting Tazmanian4:
i hope nyc get hit by cat 5 i am this kindling


Buh bye...poof!
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Quoting SOUTHFL43YRS:


I'm having trouble understanding your comments.


he is an imposter trying to mimic one of the better bloggers on here...please ignore him, he is a troll
Member Since: September 16, 2007 Posts: 0 Comments: 3650
923. Gorty
Anyone else also thinks she turned to the NNE now?
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Quoting naviguesser:
Taz_4 is not Taz = ignore


Yes, I am almost certain you are correct there.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Quoting wunderweatherman123:
so what are the chances irene reaches cat 3 again? less than 50?


I'd put the odds around 50/60%. It does have a weak internal structure right now, but the spiral bands and becoming better defined, and most models predict a 5-15 kt. jump in intensity before Irene makes landfall tomorrow morning.
Member Since: July 6, 2010 Posts: 113 Comments: 31466
Quoting Tazmanian4:
poof to your as well
Really? Must we battle the Argyle Army right now? Have you nothing better to do with your time than play with a sockpuppet? I pity you.
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Mission 29 is en route to Irene. It will be interesting to see if the central pressure continues to rise.
Member Since: June 29, 2009 Posts: 13 Comments: 5300
Being a long time lurker, but never poster, can I ask why people on this blog get so caught up in rooting for the storm to become stronger or weaker? Is there some sort of betting pool I missed?

Isn't it more important to analyze facts?
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Taz_4 is not Taz = ignore
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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.
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Happy to join you guys. Been lurking from Ft. Laud
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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.


Most people in this region haven't even experienced a true tropical storm. This system is forecast to come in as a Category 1 hurricane, into an area that is known to receive widespread tree and power line damage just from typical severe thunderstorms.
Member Since: November 17, 2010 Posts: 11 Comments: 527
Quoting FLdewey:


Something tells me he's okay.


Sounds like you know who it really is...
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Quoting weatherman321:
If this storm ends up a tropical storm an is to the east of NYC I'm afraid people will be even more reluctant to listen to officials for the next storm that could take Irene's path in the future... Besides that stay safe everyone


Well those people would be quite ignorant.
Member Since: June 29, 2009 Posts: 13 Comments: 5300
A westward motion should continue with 91L over the next couple of days. After then, the trough that is expected to turn Irene to the ENE just come and swoop up 91L as well. It is possible that 91L makes it to tropical storm status before it is absorbed by the front, and with the way things have been going in that area so far this season, I wouldn't doubt it...

Member Since: July 6, 2010 Posts: 113 Comments: 31466
Quoting wunderweatherman123:
so what are the chances irene reaches cat 3 again? less than 50?
100% should be at 115mph by 8 A.M. Sat. morning.
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Quoting Tazmanian4:
Extrap. Sfc. Press: 943.4 mb


? There's no recon in the centre at the minute...
Member Since: August 10, 2010 Posts: 2 Comments: 1971
If this storm ends up a tropical storm an is to the east of NYC I'm afraid people will be even more reluctant to listen to officials for the next storm that could take Irene's path in the future... Besides that stay safe everyone
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Quoting Tazmanian4:
i hope nyc get hit by cat 5 i am this kindling


I'm having trouble understanding your comments.
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Quoting Melagoo:
Comparison with Nanmadol and Irene

Nanmadol - 155 mph



Irene - maybe 100 mph



Sure Irene is huge but that thing in the Pacific is a real monster.
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Quoting TropicalAnalystwx13:


FINALLY! SOMEBODY WITH COMMON SENSE!!!

+1
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Media is overplaying this big time Im in Wilmington Wrightsville Beach the wind is about 15mph right now. But of course the media is telling everyone in New york and Philly that we are getting battered right now. They have evacuations and closing down casinos in Atlantic city....Anyway heres the statement from Wrightsville Beach>>


Town Of Wrightsville Beach Establishes Curfew

WRIGHTSVILLE BEACH - The Town of Wrightsville Beach is currently under a Hurricane Warning. The current forecast indicates that our area will experience tropical storm conditions beginning Friday evening, and we may experience hurricane conditions on Saturday.

While a mandatory evacuation is not anticipated, Town of Wrightsville Official are strongly encouraging a voluntary evacuation of residents in beach front and low-lying areas due to the potential for power outages, storm surge, and flooding.

As a result of the State of Emergency, a curfew has been established for Friday August 26th beginning at 10:00 p.m. through Saturday August 27th at 7:00 a.m. Traffic over the Heidi Trask Drawbridge on to Wrightsville Beach will be limited to residents, employees and others with an essential need for access.

Non-essential services have been suspended and Town Offices will close at 2:00 p.m. Friday, August 26th.

Information about the storm and any other preparations is available on the town’s website at www.towb.org
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It is hard to compare one storms effects to another. At landfall several things will determine the damage it leaves. But the storm surge is the deadliest.
After Katrina hit, the mayor of Biloxi said that Hurricane Camille killed more people in 2005, then in 1969 when it hit.

One of the big reasons Camille was one of the most powerful storms to hit the US, but it was a small tight storm. A lot of people said that Camille was a 5 when it hit and we were okay here, but Katrina is a 3 we will be ok. Wrong.

Irene is a big wide storm like Katrina and it bought in a lot of surge with it. When that water hits the coastline it it just keeps going in. Bays fill up and if the wind is at the right angle the surge will even get higher. Also it will back up in the rivers for miles. Irene will cause a lot of flooding.

Where I live is about 40 miles from where both these storms made landfall. After Camille there was some flooding here, but not like after Katrina. The city of Pascagoula just about every house south of Hwy 90 had water damage. And right on the coast add wave action, that is above the storm surge. Also add the 10-15 inches or more of rain that will be added on top of the surge.

If you can not make up your mind about leaving, read "Katrina Storm Surge" by Margie Keiper. its on the main 'Tropical Page', under 'Hurricane Resources'.
She gives a very detailed report on the Surge, From Grand Island LA, to The Florida Panhandle.

Remember this if the water comes up, you will likely be on your own, because help may not be able to get to you.
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Quoting Levi32:


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.


Oh, okay, Thanks.
Member Since: July 6, 2010 Posts: 113 Comments: 31466
894. wpb
as nhc has said we do a vgod job with the track
we need to improve our ability to forecast intensity

true again in 2011. think the dry air and shear were under weighted.

noting both hmdl and gfdl show increase in strenght before landfall?????
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Quoting TropicalAnalystwx13:
Invest 91L:



Eh? Missed that lol
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Tazmanian4 7:20


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so what are the chances irene reaches cat 3 again? less than 50?
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Quoting NOLALawyer:
I guess school is out for the day in enough places for the kids to get back on the board.

This is how I look at Irene. She is going to cause severe damage to NC. Flooding is her biggest threat, and it will likely be massive. After that, everything else is academic. Even if she literally vanished from sight an hour after she lands, she will have earned a retirement. And, let's not forget what she has already done to PR, the DR and the Bahamas.



You know, adults do a lot of this too. So instead of automatically jumping on "us kids", why don't you find out if they are actually kids or not. ;)
Member Since: July 6, 2010 Posts: 113 Comments: 31466
Quoting Levi32:


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.


Hopefully they are dead wrong about Irene making a comeback. Hopefully weakening continues throughout its lifetime.
Member Since: June 29, 2009 Posts: 13 Comments: 5300
Quoting HCW:
TWC just said that it's the storm of  your lifetime if you are in the NE


A tropical storm. So overly dramatic. There will be some significant effects but that statement is over the top.
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Quoting TStormSC:
Tigger? What's the latest down there? Heard something about a surfer on IOP?


kite boarder near sullivan's island was spotted bout mile out...then that bad feeder band hit...last i heard they were still looking for him
Member Since: September 16, 2007 Posts: 0 Comments: 3650
Invest 91L:

Member Since: July 6, 2010 Posts: 113 Comments: 31466
Comparison with Nanmadol and Irene

Nanmadol - 155 mph



Irene - maybe 100 mph

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Quoting Tazmanian4:
Guys i this farted may be i this make this storm march stronger


HUH?
Member Since: August 28, 2006 Posts: 6 Comments: 2895
I guess school is out for the day in enough places for the kids to get back on the board.

This is how I look at Irene. She is going to cause severe damage to NC. Flooding is her biggest threat, and it will likely be massive. After that, everything else is academic. Even if she literally vanished from sight an hour after she lands, she will have earned a retirement. And, let's not forget what she has already done to PR, the DR and the Bahamas.

Member Since: September 3, 2009 Posts: 0 Comments: 520
Quoting ShenValleyFlyFish:
Utter silliness. That kind of snow in those places would be front page headlines the world over.
But it has happened before (the snow) so: 1)it's not utter silliness and 2) people behaved exactly the way DavidHOUTX described. It's human nature.
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880. Gorty
NNE looks like has begun. Less interaction down south means stronger system for New England and LI.
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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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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.