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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1899. Seastep
RAMSDIS 1KM radar:

Loop

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1897. cwf1069
Quoting TampaSpin:
OZ is freaking crazy.........OMG

Can you give me the link please?
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1896. IMA
Quoting Beachfoxx:
Did you was and wax it?? You gotta do both to get significant rainfall. : )

Yeah, and put pink eyelashes on it - seriously :)
Sorry I didn't call today, he was glued to me until he went to bed. LOL <3
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Quoting Beachfoxx:
Ditto that!
*applause*
Most of us (Floridians) watch EVERY storm like it is our storm... we've been hit, lost our homes, been without power, water & other basics... we do not "wish" for anyone to be impacted by these storms --- what we do want is to know that people are prepared & heed the advice of the local authorities. Your decision could be a matter of life or death.
Be safe & stay alert...

Double ditto but for me it was 1992 Andrew that I dont want anyone else to suffer through. Florida is the nations speed bump because we can handle it. Its a fair trade beautiful weather and women 90% of the time, to deal with these things 10% of the time
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Turn Turn Turn Fish Storm
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This next band moving on shore NC will be bringing an elevated wind speed. Looks like it's trying to complete an eye again.

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1892. Levi32
Wow is that really Oz...what a character lol. I'm glad for a live feed of the storm conditions wherever he's at - I assume on the outer banks.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Did you was and wax it?? You gotta do both to get significant rainfall. : )
Quoting IMA:

Girl, my poor black car is speckled now, from the shower yesterday that did nothing but dirty cars & back-up traffic (and temporarily lift my spirits - was awesome to smell rain again)
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Quoting NoVaForecaster:


Cant find in on the NOAA site. Still searching though.


http://cimss.ssec.wisc.edu/tropic/real-time/marti /2011_09L/webManager/mainpage.html
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That NE turn recently had prevented TS force winds from reaching Raleigh and Irene is a regular to heavy rain event west of I-95. I don't live east of I-95, so I have no clue what's going on. Irene is more than just rain event however for Eastern NC with high winds, tornadoes, and surge at NC coastline.
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Quoting KATRINABILOXIGIRL:
He's hilarious, I am listening and watching right now...

link please!
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1886. HCW
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RogerEdwardsSpc: Mhx now shows large looping hodographs and the area Profilers are detecting 50 - 60 1km wind fields


RogerEdwardsSpc: People in the area sleep with a weather radio as the tornado risk is huge.
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1884. HCW
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1883. IMA
Quoting Beachfoxx:
I keep telling you to leave your umbrella at home & to wash & wax your car -- guaranteed to rain soon afterward!

Girl, my poor black car is speckled now, from the shower yesterday that did nothing but dirty cars & back-up traffic (and temporarily lift my spirits - was awesome to smell rain again)
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1882. docrod
Quoting NJcat3cane:
just heard there will be a special advisory at 1am? anyone know if this is true..waiting in AC NJ right now


NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORIES...100 AM EDT AND 300 AM EDT.
NEXT COMPLETE ADVISORY...500 AM EDT.

$$
FORECASTER STEWART
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Quoting TampaSpin:
OZ is freaking crazy.........OMG
He's hilarious, I am listening and watching right now...
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1880. whitewabit (Mod)
If Irene stays on this same heading she may miss landfall in NC ...
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I keep telling you to leave your umbrella at home & to wash & wax your car -- guaranteed to rain soon afterward!
Quoting IMA:

It's the only way for any of us from San Antonio to see rain
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I wanted a drought breaker storm, but not when East Coast get slammed at the same time...
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just heard there will be a special advisory at 1am? anyone know if this is true..waiting in AC NJ right now
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Quoting floodzonenc:
Thanks Mel. Posts like that prove that despite the dysfunction we can have up here at times, the WU crew are the "bee's knees"...


Please be careful Flood!! Big, big prayers with you!! Mel
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OZ is freaking crazy.........OMG
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1874. hamla
Quoting MississippiWx:
186...Jose deepens and begins to feel a weakness to the north. Anyway, pretty far out now...but the GFS is showing the potential for the Atlantic to explode.



is that low in boc the one that could make t.s??
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1873. IMA
Quoting jonelu:
You drove all the way over for the storm.

It's the only way for any of us from San Antonio to see rain
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1872. jonelu
Quoting c150flyer:
Greetings all... After driving 1600 miles from San Antonio I can report that I am safely in Morehead City ready to blog about conditions and take good videos as long as I am able!
You drove all the way over for the storm.
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1871. aimetti
compared to Irene around 5pm , looks much much better
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1870. jonelu
Quoting dolphin13:


I just want you to know that all of us Floridians have not stopped watching and hoping and praying that others in the path of Irene have as little damage as possible. Unfortunately I think we still have a "knee jerk reaction" when a tropical system appears to head our way...every western wobble equates to blue tarps, no electricity, massive debris, closed stores, no gas, curfews, etc. I'm sorry you've gotten the impression that once we are out.of danger, no one else matters. We, well I can speak for myself and others from FL that openly blog and support others, haven't stopped watching, waiting, and sending our best to those in any strong system's path! 2004-2005 has left a lasting scar that we wish no one else must endure, which its why my prayers and contributions have gone out to PR, DR, the Bahamas, and anywhere else forced to suffer the wrath of Irene and/or any other catastrophe our American and Island bretheren have had and will have to endure. Please be safe and know that you are in many thoughts and prayers!!!! Keep us up to date, please!! Mel
Im still here...never left.
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Quoting JGreco:


Wow...wonder if that lines up with the beginning of the weakening Texas ridge that is suppose to start at the beginning of September.:O...??


Yeah, we definitely need something. Nothing major however....just some good rain.
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1868. Levi32
Rain-rates of 0.5-1.0 inches per hour with isolated higher values are raking much of eastern North Carolina:

Member Since: November 24, 2005 Posts: 628 Comments: 26455
Greetings all... After driving 1600 miles from San Antonio I can report that I am safely in Morehead City ready to blog about conditions and take good videos as long as I am able!
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186...Jose deepens and begins to feel a weakness to the north. Anyway, pretty far out now...but the GFS is showing the potential for the Atlantic to explode.

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Quoting MississippiWx:
172...Jose, Katia, and Lee?



hmmm, wonder if those will be East Coast bound....
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Quoting GTcooliebai:
Yep just as I feared, SAL is non-existent:

Two waves emerging off Africa.
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Ditto that!
*applause*
Most of us (Floridians) watch EVERY storm like it is our storm... we've been hit, lost our homes, been without power, water & other basics... we do not "wish" for anyone to be impacted by these storms --- what we do want is to know that people are prepared & heed the advice of the local authorities. Your decision could be a matter of life or death.
Be safe & stay alert...
Quoting dolphin13:


I just want you to know that all of us Floridians have not stopped watching and hoping and praying that others in the path of Irene have as little damage as possible. Unfortunately I think we still have a "knee jerk reaction" when a tropical system appears to head our way...every western wobble equates to blue tarps, no electricity, massive debris, closed stores, no gas, curfews, etc. I'm sorry you've gotten the impression that once we are out.of danger, no one else matters. We, well I can speak for myself and others from FL that openly blog and support others, haven't stopped watching, waiting, and sending our best to those in any strong system's path! 2004-2005 has left a lasting scar that we wish no one else must endure, which its why my prayers and contributions have gone out to PR, DR, the Bahamas, and anywhere else forced to suffer the wrath of Irene and/or any other catastrophe our American and Island bretheren have had and will have to endure. Please be safe and know that you are in many thoughts and prayers!!!! Keep us up to date, please!! Mel
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Getting stormy here, with gust of 40-60 mph, but winds are averaging in 20-30 mph range... I think it won't get worse than this, so I think Raleigh will be fine for now. It isn't raining heavily here either... I think we won't get TS condition here tonight/tomorrow.
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Quoting floodzonenc:
Raining its butt off in Greenville! Pressure is 29.47 and over 2 inches of rain already.

Lord, let me focus on my assignment that is due in 23 hours! Kids, let this be a lesson... don't procrastinate. I am torn between the weather and this crummy research paper :)


Procrastination is something that I too can't seem to get rid off. You always feel that doing something else would make you feel better, but in reality the longer you put your work off, the worse you feel later.
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It's absolutely disheartening to see people complaining about a storm that's turned into "nothing", or speak about things being overhyped, or wasting time and money preparing for a fizzle.

Over the last several years, hundreds of thousands of human beings have been washed out into the ocean by tsunamis because they weren't fortunate enough to have enough advanced notice to prepare, or technology that could give them several days to get to safety, or even a moment to speak with their loved ones before their lives ended.

Whether Irene is the monster that was predicted is beside the point of all of this. We, as citizens of the United States, have the fantastic fortune to have satellites, and bouys, emergency responders, and hurricane experts working in unison to prevent such horrific tragedies from happening!

Donate your supplies to a charity, save them for the future and consider yourself prepared, or use them up. Take a moment to reflect on how fortunate you are to even be able to complain at this moment in time because you have electricity, and a computer, and you haven't been washed away by a monster.

Let's get back to keeping people safe and stop wasting blog space with complaint and one-upmanship.
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1857. docrod
Quoting sunlinepr:


Oh man, not again... here they come


Yes - I was looking at that a few hours ago ... lots of dancers lined up for September!
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172...Jose, Katia, and Lee?

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If anyone would like to join i have Roger Edwards form the Storm Prediction Center blogging......come on over
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1852. JGreco
Quoting MississippiWx:
150...



Wow...wonder if that lines up with the beginning of the weakening Texas ridge that is suppose to start at the beginning of September.:O...??
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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.