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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Levi. Check 4km IR Arent the cloud tops cooling again?

http://weather.hawaii.edu/satellite/satanim.cgi?r es=4km&banner=uhmet&chnl=ir&domain=asb&size=large& period=720&incr=30&rr=900&satplat=goeseast&overlay =off&animtype=flash
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http://www.ndbc.noaa.gov/station_page.php?station=4 1013

Frying Pan Shoals
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Unless it turns SHARP NE all the sudden, Irene will landfall between SC/NC and Morehead City.
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Quoting Gorty:
To those who say people are hyping this up. Guess what? Remember that ice storm in 2008? People were hyping that up too? Well it DID play out! Sure the hype was useless for me, I just got plain rain but many other areas got clobbered with the crippling ice storm.

So for some, the hype was right and for others the hype was wrong.


Indeed. I imagine forecasting Ice accumulation in specific areas is very difficult. The amount we saw in 2008 takes a pretty special setup with the Temperatures. It was one of the most beautiful things i've ever witnessed when i woke up in the morning, but I was also without power for over two weeks.
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obx cams
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1174. LargoFl
Washington d.c would anyone know how bad the flooding would be inside the city itself?
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Quoting BobinTampa:
Isn't the storm surge much greater when a storm is coming in perpendicular to the coast? Since Irene is basically skirting the coast, wouldn't that lessen storm surge concerns for most of the coast (except for RI and Conn)?



Parts of North Carolina are perpendicular to Irene. Some of the Barriers are aligned west southwest to east northeast which would be perdicular if the storm was moving NNW, but shes movin North right now.
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1171. Gorty
Idk to you downcasters, more and more expert weaher forecasters are agreeing with each other for me in western Mass for winds to be over 40 and 50 mph with higher gusts... Gusts don't know yet, right now could be 60-80 or more mph
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Quoting Tazmanian:
did they ban him?


Ahhhh, we finially have the REAL Taz. Good to have you back on.
Member Since: September 2, 2010 Posts: 0 Comments: 81
Picture Irene as a plow, from her storm surge, then picture the entire time 60+ mph winds keeping all that water out in front of the "plow" from escaping.

This effect, combined with the size of the system, slow forward speed, abnormally high tides.

There is no over hyping this system, it is as they say, "Once in a lifetime".
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Shear and dry air continues to pummel Irene's core......

To me, I don't see any way Irene can organize itself and spin out the dry air enough to re-obtain Major status....

I fully expect Irene to make landfall as a strong Cat 2 storm. But because of the tremendous size of Irene, this STILL will be a record breaking storm in several area's!

I wish those in harms way the best of luck!

Here is an image (water vapor) which shows Irene allowing dry air to entrain into the core.......

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1167. Levi32
Quoting Jedkins01:


Irene should continue weakening, I highly doubt we will see Irene make landfall as a category 3, and based on what the NHC said about Irene not transitioning its highest winds to the surface, I would expect NC to get a wind maximum of category 1 strength if the eye wall actually makes landfall. However, hours of tropical storm strength winds with gusts to hurricane force should cover a rather large area near the coast.

To me its clear that Irene reaching major hurricane status again is quite unlikely.

Although Irene is suffering from dry air intrusion, that's only relative to preventing growth, its kinda hard to call a hurricane dried out. That's sort of oxymoron-ish, lol.



It's very bad to assume that the winds at flight-level over the water won't come cascading down to the surface over the land as turbulence increases. If it's 950mb, Cat 3 gusts could find themselves hitting the surface. It's not wise to play this down, even if it is not upgraded later today.
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1166. jonelu
Quoting Tazmanian:
did they ban him?
I dont know but I reported him 6 times..
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Quoting Melagoo:
That is because the are all still intouch with Mother Earth we lost that ability long ago


Aren't birds sensitive to changes in atmospheric pressure?
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does any one have a link to a live cam off the coast of NC?
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did they ban him?
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My neighbor just brought in his 25 ft boat his family in Wilmington was holding... couple of cars came to my other neighbor's family from Wilmington area came here and brought in suitcases. At least we got special garage to store our boat here...
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1161. Melagoo
Quoting TexasGulf:
Someone posted earlier that all the birds were gone from their area around New York or Jersey. If the birds are GONE and everything is quiet... that's not a good sign.

In Beaumont, Tx for Hurricane Rita... our trees were filled with birds that fled from western Louisiana. The birds KNEW and evacuated to safer areas.

If the birds are gone and you see no squirrels... everything seems quiet and still... then I would do what THEY are doing. Call your friends further West and see if their trees are unusually full of birds. If so, then consider leaving and going where the birds went. They sense the weather and won't stay in an unsafe environment.
That is because the are all still intouch with Mother Earth we lost that ability long ago
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Quoting TexasGulf:
Someone posted earlier that all the birds were gone from their area around New York or Jersey. If the birds are GONE and everything is quiet... that's not a good sign.

In Beaumont, Tx for Hurricane Rita... our trees were filled with birds that fled from western Louisiana. The birds KNEW and evacuated to safer areas.

If the birds are gone and you see no squirrels... everything seems quiet and still... then I would do what THEY are doing. Call your friends further West and see if their trees are unusually full of birds. If so, then consider leaving and going where the birds went. They sense the weather and won't stay in an unsafe environment.


Yeah i seen that post. Calm before the storm.
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1159. Levi32
Quoting ecupirate:
Levi & Others

Here is a live local news stream for Eastern NC

Link


Thanks a lot.
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1158. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 163 Comments: 52096
Hi Cyber, nice to see you on the blog.
Member Since: September 2, 2010 Posts: 0 Comments: 81
Invest 91L is 35mph
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1155. Gorty
To those who say people are hyping this up. Guess what? Remember that ice storm in 2008? People were hyping that up too? Well it DID play out! Sure the hype was useless for me, I just got plain rain but many other areas got clobbered with the crippling ice storm.

So for some, the hype was right and for others the hype was wrong.
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anybody got a link to Oz's chase?

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Hurricanes #1 killer is storm surge. This entire situation reminds me of Ike, except off the US coast instead of in the Gulf of Mexico. Irene, even though its a Category 2, is generating massive swells and will be generating Isabel-style surge to North Carolina, I suspect that the effects will be similar. The thing is, Irene is massive, and probably pretty high up on the IKE Scale. This is a very serious situation, and further proof why the current Hurricane scale should be discarded for one that takes in account both the wind and surge. Ike and Irene are absolute proof of that.
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Isn't the storm surge much greater when a storm is coming in perpendicular to the coast? Since Irene is basically skirting the coast, wouldn't that lessen storm surge concerns for most of the coast (except for RI and Conn)?

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Quoting NavarreMark:


Yep. He's had enough beans for now.

Howdy Cosmic.

Hope your staying safe. That means I hope your Being Safe.


How peculiar that most of us on this blog enjoy each other's sense of humor and quote the same old, classic and whacky movies!
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1149. franck
Irene was shot...Bobby, Irene was shot!!!
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Quoting stormchaserDAZ:
alright keep ure panties on jesus christ im intitled to my opinion and my opinion is that irene will be downgraded to a weak cat one unless she can get her act back to gether wich i find highly unlikely theres no need for name calling were mostly all profecionals here


Finally. A funny post...yeesh
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Someone posted earlier that all the birds were gone from their area around New York or Jersey. If the birds are GONE and everything is quiet... that's not a good sign.

In Beaumont, Tx for Hurricane Rita... our trees were filled with birds that fled from western Louisiana. The birds KNEW and evacuated to safer areas.

If the birds are gone and you see no squirrels... everything seems quiet and still... then I would do what THEY are doing. Call your friends further West and see if their trees are unusually full of birds. If so, then consider leaving and going where the birds went. They sense the weather and won't stay in an unsafe environment.
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Quoting Levi32:


Right, the models are seeing the water. It's hard to tighten up the core of a dried-out hurricane as large as this though, and the Gulf Stream is very thin. The models may be responding too quickly to it, but we will see. I've had my forecast for a low-end Cat 3 at landfall for a while now, and I'll stick to it based on what we're seeing today.


Irene should continue weakening, I highly doubt we will see Irene make landfall as a category 3, and based on what the NHC said about Irene not transitioning its highest winds to the surface, I would expect NC to get a wind maximum of category 1 strength if the eye wall actually makes landfall. However, hours of tropical storm strength winds with gusts to hurricane force should cover a rather large area near the coast.

To me its clear that Irene reaching major hurricane status again is quite unlikely.

Although Irene is suffering from dry air intrusion, that's only relative to preventing growth, its kinda hard to call a hurricane dried out. That's sort of oxymoron-ish, lol.

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A hurricane is like a race car - even if it flames out its gonna hit something hard and do some damage.
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Research HWRF (purple) does not forecast restrengthing, while the operational does. This is from 06Z, the problem with the research version, it is not timely.


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Levi, try www.nbcnewyork.com They have live stream. I would think CNN and the Weather Channel may have live stream when it gets close.
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Quoting Levi32:


Right, the models are seeing the water. It's hard to tighten up the core of a dried-out hurricane as large as this though, and the Gulf Stream is very thin. The models may be responding too quickly to it, but we will see. I've had my forecast for a low-end Cat 3 at landfall for a while now, and I'll stick to it based on what we're seeing today.


Thin yes, but also deep. The maps almost look like she'll track right along it for the next 13 hours until 8am tomorrow morning passing the outer banks, dead smack in the middle of this deep hot current.
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Irene probably will not strengthen much if any before landfall based on MIMIC which reveals a slowly decaying core. On the flip side, Irene is and will probably remain massive.
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1137. Levi32
West Beach, NC is already getting gusts to tropical storm force and periodic sustained winds above 30mph.
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Levi & Others

Here is a live local news stream for Eastern NC

Link
Member Since: July 27, 2011 Posts: 0 Comments: 204
Quoting VAbeachhurricanes:
Anyone have a link that lists evacuation orders?

http://www.vaemergency.gov/
Link
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The mere fact that Irene was a Cat 3 is going to be enough to create a storm surge reminiscent of a Cat 3 hurricane. Just look at what happened with Katrina (no, I am not saying that this is going to be like Katrina, just showing an example), she weakened to a Cat 3 before landfall, yet still produced a Cat 5 surge.
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While the attention is now focus on hurricane Irene the the devastating consequences for the eastern seaboard of the CONUS, my attention as a resident of the lesser antilles is now focused on the consistent runs of the reliable models, that a very strong cyclone will plow through the windward islands around the 6th of sept. the disturbance is about to exit the african coast the next 24 hrs. Like the residents of the eastern usa who can see their plight, we in the ilands have to wait for this scenario to play out.
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Update
*All graphics can be magnified by clicking on them (they can also be further magnified in the new window by clicking on the graphic)






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About JeffMasters

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