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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NAO went moderately positive today folks. Look for more ridging on the east coast and west tracks after Irene's passing, assuming it holds positive.

25Aug2011 -0.62453E+00
26Aug2011 0.48188E-01
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Quoting MHCgirl:
The local forecasters here have downgraded the storm. It seems like we are in for just a windy day with a few inches of rain on the coast of NC. Not at all what was expected but happy to know that we won't be cleaning up a mess come Sunday.


I think you should keep an eye on Irene. There are more than a few that believe she still has some tricks up her sleeve. The storm surge is still going to be bad no matter what the storm does.
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Quoting wunderweatherman123:

384 hours out we have a hurricane in the Gulf of mexico from the tropical storm in the bay of campeche and tropical storm in the carribean. both of them combined to become a hurricane. in this run the hurricane is moving due north towards lousiana. Credits to the 18z GFS.


Nobody but you can see the pics; remote linking has been disabled on that site.
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Quoting TropicalAnalystwx13:


Nope, still north :P

Blargh!
lol
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Quoting NoVaForecaster:


It doesn't look likely that storms will get In the GOM but if they do the water temp is like 94 degrees and the storm would absolutely explode. I give it a 40% chance that a storm makes it in there IMO. I hope that none do regardless
Quoting rkay1:
You made a good prediction and looks to be playing out just the way you said.  I also agree and believe that anything that forms will head for STX or Mexico.

I have seen this type of pattern before where a strong high pressure set's up over Texas and literally REFUSES to go any where.Yes it has shifted back and forth over the south west but it's not really dying out like every wants it to.And your right.If a storm does find it's way in the Gulf with those SST it ain't gonna be petty for someone.
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447. AVL
Quoting MHCgirl:
The local forecasters here have downgraded the storm. It seems like we are in for just a windy day with a few inches of rain on the coast of NC. Not at all what was expected but happy to know that we won't be cleaning up a mess come Sunday.


Well, Thats good to know...WE usually get 90 mph winds with our rains up here in the mountains to...
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Quoting MHCgirl:
The local forecasters here have downgraded the storm. It seems like we are in for just a windy day with a few inches of rain on the coast of NC. Not at all what was expected but happy to know that we won't be cleaning up a mess come Sunday.


I'll be glad when you loose power, so you idiotic posts don't waste blog space, good luck and have fun trying to get on the blog for a few days if not weeks
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Quoting WeatherNerdPR:
Radar would seem to show NNE motion. I'm probably wrong, though.


Nope, still north :P
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384 hours out we have a hurricane in the Gulf of mexico from the tropical storm in the bay of campeche and tropical storm in the carribean. both of them combined to become a hurricane. in this run the hurricane is moving due north towards lousiana. Credits to the 18z GFS.
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Quoting NoVaForecaster:


It doesn't look likely that storms will get In the GOM but if they do the water temp is like 94 degrees and the storm would absolutely explode. I give it a 40% chance that a storm makes it in there IMO. I hope that none do regardless


GOM had not had a deep heat tapping hurricane for several years before 2004. The place was rigged to blow and blow it did.
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Radar would seem to show NNE motion. I'm probably wrong, though.
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360 hours out the tropical storm in the carribean that made landfall in the NE yucatan swallows up the tropical storm in the bay of campeche now the tropical system is NW of the yucatan
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The local forecasters here have downgraded the storm. It seems like we are in for just a windy day with a few inches of rain on the coast of NC. Not at all what was expected but happy to know that we won't be cleaning up a mess come Sunday.
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Quoting rkay1:
IMO, we are seeing the same old patterns of late. South Texas/Mexico and Curving out to sea. I don't want to sound like a cynic but I hope everyone got their thrills from Irene because I don't see another real threat this season (CONUS). Its almost like the US used up all its hurricanes in 2005.


I am not sure how to respond to this.. there's a hurricane about to hit the US coast. Your point is pretty much invalid.
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26 ft waves at this location.


Member Since: August 29, 2010 Posts: 0 Comments: 5236
436. yoboi
Quoting cntrclckwiseSpenn:


The Euro breaks down the texas ridge, but the GFS still has the high in place 8-10 days out? I guess thats not good news for FL's west coast if the GFS holds true since the weakness seems to be in that area.

The Storm is now over the DR correct? So who knows how much development will be available with it going over hispanola and cuba...



true
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At least up to this point, Irene seems to be doing a good job protecting her inner core from the dry air intrusion. Will be interesting to see which wins the battle.
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Quoting MrstormX:


Who knows, the guys clearly lost his mind.

he has been right about Irene from a week before she formed so I would say he lost his mind. He was saying east coast when everyone else was saying gulf then Florida.
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tropical storm in the bay of campeche tropical storm making landfall in the north eastern yucatan 324 hours out
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Quoting HurricaneDean07:
Be back tomorrow... Its my birthday going out to celebrate. :)


Happy anniversary of your birth! Have Fun, Be Safe.
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Quoting HurricaneDean07:
Be back tomorrow... Its my birthday going out to celebrate. :)


Happy Birthday and have a great time :)
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426. 996tt
GOM is bad for storm surges. All of the water from storm gets pushed in and there is no where for it to go. Hopefully, Irene storm surge won't be nearly as bad as Ike.
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Quoting HurricaneDean07:
Be back tomorrow... Its my birthday going out to celebrate. :)

Have a happy Birthday!
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Quoting wunderweatherman123:
Is it true the death texas ridge is forecasted to completely break apart? if it does the US gulf coast will now be at risk for tropical systems too....
Back in June I had given my opinion about not seeing to many Gulf storms this year.However no one believed me.And I got jumped on upon.We'll have to see how September goes.
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Quoting superpete:
For anyone in the impending power outage areas,this is an easy way to retain communication by laptop computer, providing the network remains active.You will need the following:
A 1000 Watt Inverter ( Converts DC battery power to 120 volts ac)
A power strip or extension cord with multiple 120 volt outlets
A vehicle 12 volt battery, marine/ RV deep cycle or cranking battery
A positive and negative connection between the Inverter & vehicle battery, AWG 8 (8 gauge wiring)
Connect your modem &/or the wireless WiFi hub to the inverter as your computer requires. Turn Inverter ON & moniter the 120 volt output to the connected equipment.You will also be able to even charge the laptop battery for a short while. A deep cycle RV battery should provide at least an hour or two of run-time.Good luck to all on the East Coast through this weekend.
SP


I have also been posting similar information, However, the 400W with 800W surge you can get from truck stops for $30 to $40 is more efficient than the 1000W. None of the 200w inverters I have tested are any good. DEEP CYCLE batteries from Walmart have proven excellent value for me. If you have a vehicle, DO NOT use the car battery. If you do the battery will be ruined within a few cycles and you will not have power to start the car. When the deep cycle battery gets low, start the car and then use jumper cables or a charging cable to recharge your deep cycle battery - should take less than 20 minutes to charge. I get up to 7 hours of computer / router (plus 45 mins or so with a 7W CFL light)time on a charge. I run the computer off the inverter - recharging the computer battery takes more power than running on power!
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Waves really coming in now...Topsail Link
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Quoting ProgressivePulse:


Why the surprise? Intensity forecasts are well advertized to be poor. Just be thankful Florida and North Carolina both dodged a serious situation. The Bahama's however were not so lucky and received the max that Irene had to offer. A serious situation still applies to the NE in the form of rain and storm surge, hopefully they can dodge a bullet as well. That would be the best outcome that could be expected with Irene at the moment.
As I intimated on the earlier blog, Irene's danger is going to be the size. Sure, it's only cat 1 winds, but after 24 hours of that, anything not tied down is going to be gone... Give me a few minutes to post my pictures so you can see what TS winds did. More importantly, the surge is likely to be quite large. This is what east coast residents need to be concerned about.

Frankly, anybody who is disappointed that Irene isn't going to be worse should have been in Acklins and Mayaguana, where they got the cat 3 winds directly - and where they will be without water, power, and telephone service for nearly two weeks.
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Quoting 900MB:
If it wobbles any farther east, then yes.
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Quoting 900MB:
NYC reporting. Outflow clouds have moved into the city and it is muggy as heck. The city has been in panic mode all day, ever since Bloomberg announced that mass transit will be shut completely tomorrow. Shutting mass transit means that all of the stores will close 2 hours earlier. There were long lines to get into the local fairway supermarket and 2 security guards at the door controlling the crowds. Everyone was civil but plenty of nervous energy going around. There was a rumor that a curfew would be instituted as well.
What concerns me most is if this is a total dud. Believe me, next time NYers will think they are crying wolf again and then disaster could ensue.


I disagree with that this storm is a dud. It might not be a CAT 2 when it reaches the city but it will be pushing a wall of water along it's path into the city. It might not be as high as it could have been had the storm not weakened but it will still be a large swell.
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Going outside in 20-30 minutes to get video for you guys :P
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Still a good-lookin' storm.
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Quoting yoboi:
central GOM needs to watch next week look south of cuba now thats what joe was talking about plus the hight over texas finally breaks next week


The Euro breaks down the texas ridge, but the GFS still has the high in place 8-10 days out? I guess thats not good news for FL's west coast if the GFS holds true since the weakness seems to be in that area.

The Storm is now over the DR correct? So who knows how much development will be available with it going over hispanola and cuba...
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It may be just my bad eyes again, but it seems as if Irene is trying to tighten the core again with tops building and getting colder.
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Be back tomorrow... Its my birthday going out to celebrate. :)
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408. 900MB
Quoting ConnecticutWXGuy:


hmm definitely a redevelopment of some deep convection around the center. I disagree with the somewhat wild predictions that this thing will restrengthen to a cat 3, but a cat 2 is probably a bit more of a possibility than advertised.


Next few frames should be interesting. Might have a chance of a higher mph number by 11. Doubt they will acknowledge any strengthening until then. We've been sliding on each advisory since 2 am, so she may be due a bounce. Stay safe up in CT, I'll hold NYC down for ya!
Member Since: June 11, 2006 Posts: 0 Comments: 684
Station 41013
NDBC
Location: 33.436N 77.743W
Conditions as of:
Fri, 26 Aug 2011 21:50:00 UTC

Winds: NE (40) at 42.7 kt gusting to 56.3 kt
Significant Wave Height: 23.9 ft
Dominant Wave Period: 16 sec
Mean Wave Direction: SE (141)
Atmospheric Pressure: 29.27 in and falling rapidly
Air Temperature: 77.2 F
Dew Point: 77.0 F
Water Temperature: 82.9 F
Member Since: August 29, 2010 Posts: 0 Comments: 5236
Quoting Wunderweatherman123:
Yep, will be down to 100! :0 <- shock face
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404. JLPR2
Quoting HurricaneDean07:
JLPR, there is nothing that tells you that Jose will go out to sea, it will head WNW cuase a weakness in the ridge then Head W when the Ridge build back in..


I'm not saying it will head out to sea, I'm saying the GFS is showing it is going out to sea.
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A restaurant in Ocean City is boarded up...

...and fishcasting.
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Quoting 900MB:
NYC reporting. Outflow clouds have moved into the city and it is muggy as heck. The city has been in panic mode all day, ever since Bloomberg announced that mass transit will be shut completely tomorrow. Shutting mass transit means that all of the stores will close 2 hours earlier. There were long lines to get into the local fairway supermarket and 2 security guards at the door controlling the crowds. Everyone was civil but plenty of nervous energy going around. There was a rumor that a curfew would be instituted as well.
What concerns me most is if this is a total dud. Believe me, next time NYers will think they are crying wolf again and then disaster could ensue.


That's the lose-lose situation that the NHC is in right now. Either it hits and is catastrophic or it hits and is nothing and then no one will pay attention the next time a big storm comes their way.
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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.

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