Irene continues to weaken

By: Dr. Jeff Masters , 8:46 PM GMT on August 26, 2011

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Satellite data and measurements from the Hurricane Hunters show that Irene continues to weaken. A 1:32 pm EDT center fix by an Air Force Reserve aircraft found that Irene's eyewall is still gone, and the central pressure had risen to 951 mb from a low of 942 mb this morning. The winds measured in Irene near the surface support classifying it as a strong Category 1 hurricane or weak Category 2. Satellite imagery shows a distinctly lopsided appearance to Irene's cloud pattern, with not much heavy thunderstorm activity on the southwest side. This is due to moderate southwesterly wind shear of 10 - 20 knots. This shear is disrupting Irene's circulation and has cut off upper-level outflow along the south side of the hurricane. No eye is visible in satellite loops, but the storm's size is certainly impressive. Long range radar out of Wilmington, North Carolina, shows that the outermost spiral bands from Irene have moved ashore over North Carolina. Winds at buoy 41004 100 miles offshore from Charleston, SC increased to 47 mph, gusting to 60 mph at 3 pm EDT, with significant wave heights of 25 feet.


Figure 1. MODIS satellite image of Hurricane Irene taken at 11:50 am EDT Friday August 26, when Irene was a Category 2 hurricane with 105 mph winds. The eyewall collapsed several hours before this image was taken, and no eye is apparent. Image credit: a href=http://rapidfire.sci.gsfc.nasa.gov/gallery/ NASA.


Figure 2. Distribution of Irene's wind field at 3:30 pm EDT Friday August 26, 2011, as observed by the Hurricane Hunters and buoys. The right front quadrant of the hurricane had about 90% of the storm's hurricane-force winds (yellow and warmer colors, bounded by the heavy black line between the "50" and "60" knot thin black lines.) Tropical storm-force winds (heavy black like bounding the light blue area) extended out 290 miles from the center of Irene. Image credit: NOAA/AOML/HRD.

Forecast for Irene
With its eyewall collapsed and just 18 more hours over water before landfall, Irene does not have time to build a new eyewall and intensify. The storm is too large to weaken quickly, and the best forecast is that Irene will be a strong Category 1 hurricane at landfall in North Carolina on Saturday. Based on the latest wind analysis from NOAA's Hurricane Research Division (Figure 2) and Irene's continued weakening trend, I predict that the 80-mile section of North Carolina coast to the right of where Irene makes landfall will receive sustained hurricane-force winds of 75 - 85 mph on Saturday at landfall; the 80-mile section of coast to the left will receive 55 - 75 mph winds. High wind shear of 30 knots will begin ripping into Irene Sunday morning when it is near Southern New Jersey, and more rapid weakening will occur. By the time Irene arrives on Long Island Sunday afternoon, it will probably have top sustained winds in the 65 - 75 mph range. However, since Irene is such a huge storm--tropical storm force winds extend out up to 290 miles from the center--it has set a massive amount of the ocean's surface in motion, which will cause a much larger storm surge than the winds would suggest. At 3:30 pm EDT this afternoon, a wind analysis from NOAA/HRD (Figure 2) indicated that the potential storm surge damage from Irene still rated a 5.0 on a scale of 0 to 6. This is equivalent to the storm surge a typical Category 4 hurricane would have. While this damage potential should steadily decline as Irene moves northwards and weakens, we can still expect a storm surge one full Saffir-Simpson Category higher than Irene's winds when it impacts the coast. Since tides are at their highest levels of the month this weekend due to the new moon, storm surge flooding will be at a maximum during the high tidal cycles that will occur at 8 pm Saturday night and 8 am Sunday morning. Wherever Irene happens to be at those times, the storm surge damage potential will be maximized. I continue to give a 20% chance that a 3 - 4 foot storm surge high enough to over-top the Manhattan flood walls and swamp the New York City subway system will occur on Sunday. The latest 11 am probabilistic storm surge map from NHC shows a 20 - 30% chance of a storm surge in excess of 3 feet in New York Harbor (Figure 4.) Keep in mind that these maps are calculated for normal tide level, and this weekend's high tides will be nearly 1 foot above normal.

Insurance company AIR-Worldwide is estimating that insured damages from Irene in the U.S. will be $1.5 - $6 billion. They estimate losses in the Caribbean at $0.5 - $1.1 billion from Irene.


Figure 3. Storm surge heights, in feet above normal tide level, which have a 20 percent chance of being exceeded during the next 3 days.  The graphic is based upon an ensemble of Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model runs using the current National Hurricane Center (NHC) official hurricane advisory. The exceedance heights depend on the historical accuracy of NHCs forecasts of hurricane track, and wind speed, and an estimate of storm size. Image credit: NOAA.


Figure 4. Overall chance that storm surges will be greater than 3 feet above normal tide levels during the next 3 days.  The graphic is based upon an ensemble of Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model runs using the current National Hurricane Center (NHC) official hurricane advisory.  Storm surge probabilities depend on the historical accuracy of NHCs forecasts of hurricane track, and wind speed, and an estimate of storm size. Image credit: NOAA.

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

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

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

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

Internet radio show on Irene at 4:30pm EDT
Wunderground meteorologists will be discussing Hurricane Irene on a special edition of our Internet radio show, the Daily Downpour, today (Friday) at 4:30pm EDT. Shaun Tanner , Tim Roche, Angela Fritz, and Rob Carver will take your questions. The email address to ask questions is broadcast@wunderground.com.

Jeff Masters

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Quoting atmosweather:
The AF plane's dropsonde went straight into the maximum wind band and this says it all regarding her strength:

Level Wind Direction Wind Speed
978mb (Surface) 320� (from the NW) 50 knots (58 mph)
977mb 320� (from the NW) 50 knots (58 mph)
972mb 315� (from the NW) 78 knots (90 mph)
967mb 315� (from the NW) 86 knots (99 mph)
942mb 320� (from the NW) 88 knots (101 mph)
935mb 325� (from the NW) 84 knots (97 mph)
917mb 330� (from the NNW) 90 knots (104 mph)
886mb 330� (from the NNW) 78 knots (90 mph)
850mb 330� (from the NNW) 73 knots (84 mph)
696mb 325� (from the NW) 63 knots (72 mph)

Earlier last night and this morning we were seeing regular reports of winds above 110 kts 3,000-5,000 feet above the surface...even in the western side of the storm they were well over 100 kts.

Unfortunately, the winds associated with Irene will not lessen the impact that the huge waves and storm surge and extremely heavy rain will have on the entire NC shore, mid-Atlantic and NE-ern coastline.


I have a different dropsonde reading at 32.03N 76.85W

Significant Wind Levels...
Level Wind Direction Wind Speed
969mb (Surface) 115° (from the ESE) 76 knots (87 mph)
948mb 115° (from the ESE) 96 knots (110 mph)
941mb 120° (from the ESE) 96 knots (110 mph)
935mb 120° (from the ESE) 102 knots (117 mph)
927mb 120° (from the ESE) 98 knots (113 mph)
918mb 125° (from the SE) 101 knots (116 mph)
911mb 125° (from the SE) 96 knots (110 mph)
885mb 130° (from the SE) 94 knots (108 mph)
876mb 135° (from the SE) 98 knots (113 mph)
850mb 135° (from the SE) 91 knots (105 mph)
772mb 140° (from the SE) 76 knots (87 mph)
697mb 145° (from the SE) 83 knots (96 mph)
The highest wind observed in the "Significant Wind Levels" section is noted in bold.
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100. MahFL
TS at LI.....lol.
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I live here (the little red dot):

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Quoting atmosweather:
Afternoon everyone!

RECON penetrating the NE quadrant and the flight level winds are significantly less intense than they were this morning. In terms of true intensity, Irene is doubtful to restrengthen because she has no eyewall or even one in the formative stages, and this is going to allow any and all dry air and mid level shear to disrupt the inner circulation. She would have to get her act together almost immediately to have enough time to deepen again.



That's great news, nobody needs a CAT4 knocking on the door. Still no slouch however, REALLY great news.
Member Since: August 19, 2005 Posts: 5 Comments: 4863
Hello , I have been reading this blog for years but never wrote in.. we are on long island and people in our area should not take this storm lightly . I grew up on the water and I know a strong easterly wind for a long period of time is not good.. The way this storm is acting it does not matter if its a class 1-2-3 or whatever...It might be a nor'easter on steriods , but by no means should people not pay attention...The trees have leaves on them this time of the year making them a big sail verses a sail boat with out sails...( I wish this blog had spell check!!!)
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Quoting MissNadia:
Well at 4:50, just had a rain band pass through Wilmington NC...Wind was ENE 42+ 52 KTs with heavy rain... vis about 1/4 mile...have white caps in the ICW... wind has now dropped of to 31 Kts,
We are 2 hours until high tide and the level is already above normal.

I'm a little southwest of the storm on Tybee Island in GA. We've had rain, significant wind, and local flooding at high tide. No major trees down or power outages.
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WV shows Irene is trying to make a comeback. I also think she is moving more NNE than N

Link
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Quoting FLdewey:
BREAKING -- Obama signs emergency declaration for New York, White House confirms

Sooo does that mean the sharks with laser beams are being let loose?

Maybe not.

More and more mets are coming to grips with reality (a hard commodity to find here)

There will no longer be a hurricane in NY...still wind, still rain, maybe even a bit of surge, but no hurricane winds. ~Denis Phillips
So they can "Bail out Wall Street"
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Quoting TropicalAnalystwx13:
All I can say is wow...I'm in for a long night.

I was thinking the same thing when I was hit. She's a lot stronger now, though. Be safe!
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Quoting NoVaForecaster:


It still does have a shot but not a good one. The eyewall would have to reform now, and there are signs of this starting to occur.



Last chance...
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Any weakening would be welcomed by many I am sure.
While I am glad that she appears (for the moment atleast) to have taken a break. I refuse to criticize anything about her at this point.

I keep thinking about the old saying "he_ _ hath no fury like a woman scorned"......

In the end, she will show us all what she is or is not made of,regardless of what I may think
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Quoting atmosweather:
The AF plane's dropsonde went straight into the maximum wind band and this says it all regarding her strength:

Level Wind Direction Wind Speed
978mb (Surface) 320° (from the NW) 50 knots (58 mph)
977mb 320° (from the NW) 50 knots (58 mph)
972mb 315° (from the NW) 78 knots (90 mph)
967mb 315° (from the NW) 86 knots (99 mph)
942mb 320° (from the NW) 88 knots (101 mph)
935mb 325° (from the NW) 84 knots (97 mph)
917mb 330° (from the NNW) 90 knots (104 mph)
886mb 330° (from the NNW) 78 knots (90 mph)
850mb 330° (from the NNW) 73 knots (84 mph)
696mb 325° (from the NW) 63 knots (72 mph)

Earlier last night and this morning we were seeing regular reports of winds above 110 kts 3,000-5,000 feet above the surface...even in the western side of the storm they were well over 100 kts.


Thanks for the analysis..good stuff
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Quoting civilbull:


Will it be a Fish Spinner?


Too far out to know for sure, but if I had to guess, No.
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Quoting Neapolitan:

From which school did you earn your doctorate in meteorology?


It's common sense. I'm not questioning Dr. Masters' credentials. I'm just pointing out the quote is now hours old and new information makes it unlikely to happen.
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Quoting civilbull:
Looks like another hurricane around september 5th as per the ecmwf and another brewing in the Gulf around the same time


I believe the GFS takes "Jose" the Sept. 5th storm and brings it into Central America. The Euro is showing a small tropical storm hitting Mexico during that same time period.
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Quoting TropicalAnalystwx13:
Power flickers, don't know how much longer I can stay on.
Where are you located?
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The AF plane's dropsonde went straight into the maximum wind band and this says it all regarding her strength:

Level Wind Direction Wind Speed
978mb (Surface) 320 (from the NW) 50 knots (58 mph)
977mb 320 (from the NW) 50 knots (58 mph)
972mb 315 (from the NW) 78 knots (90 mph)
967mb 315 (from the NW) 86 knots (99 mph)
942mb 320 (from the NW) 88 knots (101 mph)
935mb 325 (from the NW) 84 knots (97 mph)
917mb 330 (from the NNW) 90 knots (104 mph)
886mb 330 (from the NNW) 78 knots (90 mph)
850mb 330 (from the NNW) 73 knots (84 mph)
696mb 325 (from the NW) 63 knots (72 mph)

Earlier last night and this morning we were seeing regular reports of winds above 110 kts 3,000-5,000 feet above the surface...even in the western side of the storm they were well over 100 kts.

Unfortunately, the winds associated with Irene will not lessen the impact that the huge waves and storm surge and extremely heavy rain will have on the entire NC shore, mid-Atlantic and NE-ern coastline.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting TropicalAnalystwx13:


Indications are, we will be dealing with another big deal, come the next 7-10 days.


Will it be a Fish Spinner?
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Quoting TropicalAnalystwx13:


Eastern Pender County, the county north of the county Wilmington is in...(Does that make sense?)




Will do, thanks.


Makes sense. Hunker Down and keep us updated.
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Quoting TropicalAnalystwx13:
Winds were gusting at about 50 MPH here.


That is when our electricity went out in Houston during Ike..I am 3 miles north of downtown...winds were 40 gusting to 55 when the lights went out...so good luck.
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Quoting NoVaForecaster:


Wow that storm had a long track.


What really strikes me is how similar the track was to Irene, except that our 2011 storm didn't reach hurricane strength until it crossed Puerto Rico. Irene is also not expected to flee the CONUS after crossing Cape Hatteras, and although the circumstances now seem extremely rare, Irene did have a good shot at a major hurricane landfall in eastern North Carolina.
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Quoting Levi32:
It is certainly looking better than it was a couple days ago, but she's still a big deal.



Indications are, we will be dealing with another big deal, come the next 7-10 days.
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Winds were gusting at about 50 MPH here.
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Quoting Neapolitan:

From which school did you earn your doctorate in meteorology?


University of Common Sense
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Quoting JLPR2:
Seems TD10 wont be Jose...

But the one behind that one will be
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Quoting TropicalAnalystwx13:
All I can say is wow...I'm in for a long night.


Stay safe brother.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting Levi32:
Thanks Dr. Masters.

From previous blog:



Well because the shortwave is going to be passing up over southern Canada, encountering strong resistance from the Bermuda ridge over the northwest Atlantic. This will be creating a strong jet just north of New England, and if you look at the jet, it is in a great position to exhaust air from Irene's surface low via the right entrance region. Irene will be approaching New England by that time (48 hours on this GFS image). This should slow the pressure rises a bit, and I believe this is why the global models show Irene remaining very strong until she crosses Long Island.



At extratropical transition, most of Irene's rainfall will be on the western side over New England and the Canadian Maritimes. The Bermuda High set up is somewhat similar to 1938, except that the high is not nearly as strong and it is now more elongated toward the southeast. Any comparison maps?
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Seems TD10 won't be Jose...
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It is certainly looking better than it was a couple days ago, but she's still a big deal.

Member Since: November 24, 2005 Posts: 628 Comments: 26461
Quoting iceman100:


That quote is quickly becoming dated. A strong Cat 1 is not going to have Cat 4 storm surge.


I don't see how 3 foot storm surge is Cat 4 strength.
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At least those winds were associated with an outer band, and not continuous. Can't say that will last much much longer however.

Quite far from here, but close enough:
Wind Speed: NE 25 G 41 MPH
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4:53 PM 77.0 °F - 73.9 °F 90% 29.66 in 6.0 mi NE 25.3 mph 41.4 mph 0.73 in Rain Light Rain

History for Wilmington, NC
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Quoting iceman100:


That quote is quickly becoming dated. A strong Cat 1 is not going to have Cat 4 storm surge.

From which school did you earn your doctorate in meteorology?
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there's going to be post hurricane depression on the blog next week after all this turmoil and excitement.
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4:51 PM 80.1 °F 85.4 °F 75.9 °F 87% 29.80 in 2.5 mi East 15.0 mph 20.7 mph 0.05 in Rain Light Rain

History for Hatteras, NC
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Quoting Chapelhill:

I'll post it again... Dr. M's discussion said..." potential storm surge damage from Irene still rated a 5.0 on a scale of 0 to 6. This is equivalent to the storm surge a typical Category 4 hurricane would have."



That quote is quickly becoming dated. A strong Cat 1 is not going to have Cat 4 storm surge.
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Won't say much, everyone knows how serious this storm is.

Best wishes and good luck to all on the US East Coast, especially from North Carolina and New York.

Take Care.
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Quoting miguel617:


Where are you located?


Eastern Pender County, the county north of the county Wilmington is in...(Does that make sense?)


Quoting EYEStoSEA:


Will do, thanks.
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Thank you Dr. Masters
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Quoting TropicalAnalystwx13:
All I can say is wow...I'm in for a long night.

Have a safe night and we'll see ya on the other side.
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pensacoladoug,

what is the link to follow OZ?
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Afternoon everyone!

RECON penetrating the NE quadrant and the flight level winds are significantly less intense than they were this morning. In terms of true intensity, Irene is doubtful to restrengthen because she has no eyewall or even one in the formative stages, and this is going to allow any and all dry air and mid level shear to disrupt the inner circulation. She would have to get her act together almost immediately to have enough time to deepen again.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
This looks to be good news. Still weakening. Is TWC kooks still call this the storm of the century and catostrophic? Haha. Someone needs to go to Duck Island and give Stephanie Abrahms a wedgie.
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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.