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 BaltimoreBrian:


Of course tides on the NC coast are above normal now. I never said they wouldn't be.

In NY and NJ there have been several noreasters that brought high tide surges without necessitating the evac of hundreds of thousands of people.

In April 2007 all NYC tidal guages were above 4.5 feet above normal, with some greater than 6 feet above normal with a pressure of 28.60" at JFK airport and over 7" of rain in Central Park. No mass evacuations.

In Dec 1992 storm surge at NYC stations was higher. 5 to 7 feet.

And Hurricane Donna brought a surge of 11 feet to Battery Park in 1960. Hundreds of thousands lived in today's evacuation zones then. They didn't die.

I think the threat from the storm surge in the NYC area is being overhyped.

And I think the threat from river flooding inland is underhyped.
You obviously know more than I. I will agree on the river flooding. That I know something about.
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1801. Dennis8
Cape Hatteras

12:14 AM 82.4 °F 89.5 °F 75.2 °F 79% 29.52 in 4.0 mi ESE 33.4 mph 54.1 mph 0.12 in Rain Light Rain
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1800. docrod
Quoting hunkerdown:
anybody got a satellite of Africa to see what this new "potential system" originates from ?


Link
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She's heading WwW to Hatteras....lol!
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114...Strengthening a bit

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some people are going to learn from their own stupidity and mistakes. ----OR NOT. Some people never learn... Sad but true statement.
Quoting hunkerdown:
if residents of the Northeast don;t heed the advice/statements of their mayors/governors/emergency management as to the dangers and how to protect from them, what would make you think a blog would be of any help. Unfortunately, in this case, some people are going to learn from their own stupidity and mistakes.
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Quoting MississippiWx:


TY
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Quoting JustSouthofEquator:


Where's the Microwave pass when you need one :(


Member Since: August 19, 2005 Posts: 5 Comments: 4863
Quoting MississippiWx:
TD11 at 84 hours?



Always felt it was to be a TX storm, despite all the fishcasting. Doesn't seem especially eager to bust away from the ictz.
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Quoting NoVaForecaster:


No hurricane is fun. Please don't say that again, as you may offend hurricane survivors on the blog.


Wow, sarcasm is definitely wasted on you. I have lived through multiple hurricanes in NC, FL, and VA during my lifetime, so hopefully I didn't offend myself.
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NE side of Irene looks to be getting stronger on radar... not too impressed still with the IR view but the winds are there - it only needs to get a little better organized to get some of the flight level winds down to the surface.
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How come the GFS intitialized Irene at 974 mb. when the NHC & recon confirmed the pressure to be at 951 mb.?
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Quoting hunkerdown:
anybody got a satellite of Africa to see what this new "potential system" originates from ?


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I've been so busy the past two days. My father is in the hospital, had to to get part of his colon taken out again because they found a tumor that turned out to be cancerous. I also have family up in MA, so i'm a bit concerned for them as well.
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Quoting snotly:
No it was a better blog 5.2345 years ago, exactly, on a Tuesday, I remember it better than everyone else.


I beg to differ. It reached it's peak the day I joined (birthday gift to self)and has gone downhill ever since, but I had nothing to do with that. ;)
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105..Jose, with another strong wave behind him. By the way, the Euro developed this same wave on the 12z run.

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1785. Gorty
Quoting CarolinaHurricanes87:


Direct path and people on the east side is a different story. If you are on the west side (unless u r in a surge prone area), it really is nothing. As people have been saying for days


Except TWC, and my local people are all saying damaging winds with wide spread power outages on west side of the storm...
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Quoting BaltimoreBrian:


Of course tides on the NC coast are above normal now. I never said they wouldn't be.

In NY and NJ there have been several noreasters that brought high tide surges without necessitating the evac of hundreds of thousands of people.

In April 2007 all NYC tidal guages were above 4.5 feet above normal, with some greater than 6 feet above normal with a pressure of 28.60" at JFK airport and over 7" of rain in Central Park. No mass evacuations.

In Dec 1992 storm surge at NYC stations was higher. 5 to 7 feet.

And Hurricane Donna brought a surge of 11 feet to Battery Park in 1960. Hundreds of thousands lived in today's evacuation zones then. They didn't die.

I think the threat from the storm surge in the NYC area is being overhyped.

And I think the threat from river flooding inland is underhyped.


Agreed.
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Nanmadol weakens to a high-end Category 3 but is forecast to intensify. Pressure is at 940 hPa.

And it seems that Irene has a larger windfield and the more intense Nanmadol.

JTWC:
TYPHOON 14W (NANMADOL) WARNING NR 018
02 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
270000Z --- NEAR 18.2N 122.4E
MOVEMENT PAST SIX HOURS - 305 DEGREES AT 03 KTS
POSITION ACCURATE TO WITHIN 045 NM
POSITION BASED ON CENTER LOCATED BY A COMBINATION OF
SATELLITE AND SYNOPTIC DATA
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 080 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
080 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT
110 NM SOUTHEAST QUADRANT
090 NM SOUTHWEST QUADRANT
110 NM NORTHWEST QUADRANT
REPEAT POSIT: 18.2N 122.4E.TY 1111 (NANMADOL)
Issued at 04:10 UTC, 27 August 2011

Scale -
Intensity Very Strong
Center position N1825'(18.4)
E12220'(122.3)
Direction and speed of movement NNW Slowly
Central pressure 940hPa
Maximum wind speed near the center 50m/s(95kt)
Maximum wind gust speed 70m/s(135kt)
Area of 50kt winds or more Wide 110km(60NM)
Area of 30kt winds or more Wide 370km(200NM)
JMA:

Interestingly, the JTWC seems to be reporting on Irene as well.
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Quoting MississippiWx:
93...

anybody got a satellite of Africa to see what this new "potential system" originates from ?
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1780. duranta
Quoting BaltimoreBrian:


Of course tides on the NC coast are above normal now. I never said they wouldn't be.

In NY and NJ there have been several noreasters that brought high tide surges without necessitating the evac of hundreds of thousands of people.

In April 2007 all NYC tidal guages were above 4.5 feet above normal, with some greater than 6 feet above normal with a pressure of 28.60" at JFK airport and over 7" of rain in Central Park. No mass evacuations.

In Dec 1992 storm surge at NYC stations was higher. 5 to 7 feet.

And Hurricane Donna brought a surge of 11 feet to Battery Park in 1960. Hundreds of thousands lived in today's evacuation zones then. They didn't die.

I think the threat from the storm surge in the NYC area is being overhyped.

And I think the threat from river flooding inland is underhyped.


You may be on to something here.
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Quoting MississippiWx:
93...



Apparently almost every model has been developing this - has great model support and seems to develop very quickly after it emerges over the water.
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Quoting tiggeriffic:


think it was a different one...2 separate beaches... one i knew of was IOP/Sullivan's Island... they pulled em out in front of Press's house


Uh oh...press finally got him a FEMA guy
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Quoting NoVaForecaster:


New Dvorak suggesting a new eyewall has wrapped completely around the eye now. Very cold cloudtops directly over the COC. Almost looks like a *gasp* pinhole eye!

Animation:
Link


Where's the Microwave pass when you need one :(
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1775. bassis
Her cloud plume is almost touching Ct. She is one huge rotating mass of potential flood

Link
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Quoting Levi32:


You're 135 miles from the eye. I hope nobody who is in the storm's direct path takes your comment to heart.
The storm hasn't hit you yet.... give it ten hours and get back to us
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Quoting scubanaked:
Wilmington has been spared and I am safe. Wrightsville may have had worse impacts And I wish them good news tomorow but I'm shocked how weak Irene is here in wilmingon. I think the NE will be in for a big surprise they've evacuated for nothing. Just how I bought $150 of supplies for nothing.

Next time I'll trust my instincts and gut and live with what happens. I feel dumb and misled right now.

You have another ? hours before actually being hit.. Don't congradulate yourself yet


If you've never been thru a storm like this you might not feel misled once it hits. LOL
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1771. 7544
Quoting hunkerdown:
and with that setup and positioning, a West tracker...


here we go again
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Quoting MississippiWx:
Every time I look at the radar loops of Irene coming ashore, I think of Katrina. I just remember being terrified while watching the radar loops of her coming ashore...before we lost power of course. Just two monster hurricanes with massive amounts of rain and wind.

I live in Hattiesburg...winds well over 100mph here.

Katrina Radar Loop


You know how freaky it is watching that image? I am remembering when we saw her make that right turn bringing it closer to us here in Biloxi and freaking out. It is clearly visible in the loop you posted when it makes that turn. That's when we knew we were in trouble. Katrina hit at high tide here as well and that along with the surge that she generated after being so strong is what totally destroyed us. The momentum of the surge just never died down. Hope these people are prepared. Prayers are with them that is for sure.
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93...

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Quoting philliesrock:
It looks like Irene is wobbling due N or even slightly west of due N based on this radar image.

Link


Yep, she's jogging NORTH at the moment - likely a wobble. She should resume a NNE path for the rest of the night and turn a little to the left (north) tomorrow...

But if this Northward movement continues, Morehead City would be in line for landfall - again, likely just a wobble though.
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Quoting ShenValleyFlyFish:
I hope you are right about the surge but if you go to the site you posted, the real times observations at 8656483 Beaufort, NC are running above predicted and the trend doesn't look good to me. I would be very carefull what I predicted right now, or whom I listened too. Evac orders are to be respected unless you want to be Orca bait.


Shen, what conditions are you expecting at your location?
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Quoting MississippiWx:
TD11 at 84 hours?

and with that setup and positioning, a West tracker...
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Light, but steady rain now here in Virginia Beach. Wind not bad though. Maybe some 20mph gusts. The fun begins.
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1764. Ryuujin
Quoting CarolinaHurricanes87:


Ok I understand u some of u guys think preparing is the right thing and assure me doing it next time is the right thing to do thanks I appreciate the advice.

To the people taking personal shots... I could go for a jog right now if I didn't mind a light shower. Nothings happening. The beach is another story but 5 miles inland we r A okay. And as far as misled... A hurricane warning means hurricane conditions r expected. We have barely received tropical storm conditions and if u look at the radar we've received our heaviest part of the storm.


The only thing I can reckon then is that you are a Troll and don't actually live anywhere near the NC coast. Because they're getting pounded right now, as any visible footage that's been put up on this board can be seen.
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Quoting Levi32:


Find the column named "WVHT" in the data table and click on its name.

SHWEET! Thanks!
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TD11 at 84 hours?

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.
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It looks like Irene is wobbling due N or even slightly west of due N based on this radar image.

Link
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Looks to go between the NC mainland and the islands near Cape Hatteras. keeps itself over water as well on this track
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Quoting ShenValleyFlyFish:
I hope you are right about the surge but if you go to the site you posted, the real times observations at 8656483 Beaufort, NC are running above predicted and the trend doesn't look good to me. I would be very carefull what I predicted right now, or whom I listened too. Evac orders are to be respected unless you want to be Orca bait.


Of course tides on the NC coast are above normal now. I never said they wouldn't be.

In NY and NJ there have been several noreasters that brought high tide surges without necessitating the evac of hundreds of thousands of people.

In April 2007 all NYC tidal guages were above 4.5 feet above normal, with some greater than 6 feet above normal with a pressure of 28.60" at JFK airport and over 7" of rain in Central Park. No mass evacuations.

In Dec 1992 storm surge at NYC stations was higher. 5 to 7 feet.

And Hurricane Donna brought a surge of 11 feet to Battery Park in 1960. Hundreds of thousands lived in today's evacuation zones then. They didn't die.

I think the threat from the storm surge in the NYC area is being overhyped.

And I think the threat from river flooding inland is underhyped.
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Quoting MississippiWx:
At 39 hours, the GFS has a powerful Irene directly over NYC.

and it appears it wants to show the beginnings of something off the coast of Africa
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OZ is live at my blog!
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1755. Levi32
Quoting TStormSC:


Nice graph Levi! Does it come from the NDBC site? How to pull it out?

Link


Find the column named "WVHT" in the data table and click on its name.
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63 hours...GFS has our next possible tropical cyclone south of the Cape Verdes...

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Quoting Levi32:
Wave heights at a buoy south of Wilmington, North Carolina:



Nice graph Levi! Does it come from the NDBC site? How to pull it out?

Link
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Quoting Joshfsu123:



In the NHC discussion, they state extra ridging in the next 12-24 hours will keep Irene along the coastline - so if this verifies, you should see Irene bend a little more to the left once around the OBX area - this will keep it riding the coastline from Maryland/Delaware, to New Jersey and then New York.

Radar suggests she is on path to landfall in the OBX.


Not doubting the track at all, canes wobble. Close to land like this however, that jog NE just spared 25 miles of people from experiencing hurricane winds.
Member Since: August 19, 2005 Posts: 5 Comments: 4863

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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.

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