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 cloudburst2011:
I THINK THIS MORNING THE PRESSURE WAS 936MB AND NOW ITS 950MB...THIS STORM HAS REALLY FALLEN APART SINCE THIS MORNING..ITS A WONDER THEY CANT FIND AND EYE THE STRUCTURE REALLY LOOKS BAD AND THE CONVECTION HAS TAPERED OFF QUITE A BIT....WHEN AND IF IT GETS TO LONG ISLAND IT MAY BE A TROPICAL STORM BY THEN...I GUESS ALL THE DRY AIR THAT WAS STILL ENTRAINED IN THE SYSTEM THANKS TO THE ULLOVER THE SE GOM...I REALLY CANT SEE HOW THIS IS GOING TO BE CATASTROPHIC FOR ANYONE...TWC NEEDS TO CALM DOWN A LITTLE AND STOP SCARING PEOPLE...


Quit with the annoying caps... most people, me included, don't even read stuff that is in all caps because it usually means the person is just trying to get attention - furthermore they usually don't have anything useful to say.
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Quoting cjswilmingtoneye:
here in kure beach, i was wondering if someone could give me a time frame in which I should expect the strongest sustained winds and the highest gusts?


Here is your NWS official forecast...I would say those estimated winds are about right...between 60-80 mph at the peak of the conditions later tonight and early tomorrow morning, tapering off to 40-50 mph later in the morning into the afternoon. You should also expect to receive between 3 and 6 inches of rain.
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2-2.5 inches so far here according to my little rain gauge that I had to GO OUTSIDE to check.

Irene...I hate you.
Member Since: July 6, 2010 Posts: 113 Comments: 32869
Quoting TropicalAnalystwx13:


How strong did the winds get before that happened?


55-70 mph
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Quoting CarolinaHurricanes87:


Wrightsville? Be careful if that's the case... It was rough when I was out there about 3 hours ago and the storm surge at high tide will cause severe flooding around 5am


It's been rough most of the day and will b all night and tomorrow. Preparations have been made, life goes on and there's football to b watched!
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Quoting ConnecticutWXGuy:


As I have mentioned several times, there has been no Nor'Easters (not NorEasterners) that have produced sustained high end tropical storm force winds/cat 1 hurricane force winds in NYC. While I don't doubt most skyscrapers will easily withstand this hurricane, I personally would not want to be in them. The winds will be increased one full category at those high elevations, for one thing.
I stand corrected. At least on how to spell that word.
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Quoting Dennis8:


Pine trees snap..don't they. We had a lot of that north of Houston w/ Ike in the "Piney woods".


How strong did the winds get before that happened?
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894. bwat
Quoting cloudburst2011:
I THINK THIS MORNING THE PRESSURE WAS 936MB AND NOW ITS 950MB...THIS STORM HAS REALLY FALLEN APART SINCE THIS MORNING..ITS A WONDER THEY CANT FIND AND EYE THE STRUCTURE REALLY LOOKS BAD AND THE CONVECTION HAS TAPERED OFF QUITE A BIT....WHEN AND IF IT GETS TO LONG ISLAND IT MAY BE A TROPICAL STORM BY THEN...I GUESS ALL THE DRY AIR THAT WAS STILL ENTRAINED IN THE SYSTEM THANKS TO THE ULLOVER THE SE GOM...I REALLY CANT SEE HOW THIS IS GOING TO BE CATASTROPHIC FOR ANYONE...TWC NEEDS TO CALM DOWN A LITTLE AND STOP SCARING PEOPLE...
942mb at 5:00am this morning.
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Quoting
All the info I have found from local mets on WECT and NWS at ILM---peak time should be between 2 and 6am. Still not as bad as it could have been!!!

Hang on and be safe. I am just off Dow in CB


cjswilmingtoneye:

here in kure beach, i was wondering if someone could give me a time frame in which I should expect the strongest sustained winds and the highest gusts?
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I so do not want Irene to go back to major hurricane status or close to it... since the damage for SW CT could be extreme and this increase (if it happens) would be extreme^2
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Quoting weatherwart:


I have a lot of pine trees on my land. That's my biggest fear with hurricanes. In fact, I'm seriously thinking of removing one too close to my house. They uproot or break off and if they land on your roof...

I hated to do it. I live on 5 heavily wooded acres in central FL, and I love all those 150 year old trees, but after one landed on my house during Charley and a couple near misses during Jeanne...that was enough. Cut several that were a threat.
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Precipitation 2.42 in Wilmington rain so far today.
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Quoting ConnecticutWXGuy:


As I have mentioned several times, there has been no Nor'Easters (not NorEasterners) that have produced sustained high end tropical storm force winds/cat 1 hurricane force winds in NYC. While I don't doubt most skyscrapers will easily withstand this hurricane, I personally would not want to be in them. The winds will be increased one full category at those high elevations, for one thing.


3/10 was pretty bad. not for as long, though.

My weather forecast for Sunday (unreliable) is actually pretty similiar to 3/10.
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Quoting hurricanejunky:


How much rain and/or surge did you get?



very little rain...and not much surge...the flood is from the exceptionally high tides mostly...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Quoting JohninRal:


Hi. First time poster longtime lurker, and I don't want to start with an argument, but my sister is an EMT in a coastal NC County, and attitudes like the one above endanger her life. Mandatory evacuation means get the hell out. Not get out if you feel like it. Not get out if you're not an old timer who thinks he knows more than the actual meteorologists. Get out. And if you don't, you shouldn't expect emergency workers to do more than fish your waterlogged corpse out of the bay.


Have you ever heard those calls that people make to 911 when storm surge is coming in their house? The 911 operators take names and socials and wish them the best. I think everyone should have to listen to those...then maybe more people would leave. There are always some that will refuse no matter what, though. It's easy for me to say I'd leave...but I've never had to leave everything I've worked for in my life behind..that's got to be tough..but yeah..I agree..I hope your sister stays safe.
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Quoting padirescu:


As I heard it, their point of stress for evacuating the high rises in Zone A wasn't due to risk of injury by living on the higher floors. Instead it was the risk of being isolated in an emergency where first responders wouldn't be able to reach them during an emergency due to flooding at the lower / street levels of the high rise. Personally, I think this is a reasonable justification for stressing the need to evacuate. Water enters the lower levels of a high rise, sparks a fire from interaction with an electrical panel and everyone who decided to ride it out is stuck on the higher levels with an out of control fire below them.
Now this makes sense, not all the stuff about venturi effect etc. People keep asking "how hard is the wind gonna blow?" Important, but wrong question. The real question "How deep is the water going to get?"
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883. 996tt
Quoting padirescu:


As I heard it, their point of stress for evacuating the high rises in Zone A wasn't due to risk of injury by living on the higher floors. Instead it was the risk of being isolated in an emergency where first responders wouldn't be able to reach them during an emergency due to flooding at the lower / street levels of the high rise. Personally, I think this is a reasonable justification for stressing the need to evacuate. Water enters the lower levels of a high rise, sparks a fire from interaction with an electrical panel and everyone who decided to ride it out is stuck on the higher levels with an out of control fire below them.


Nope the dude talking right now said unsafe, flying stuff, debris and etc. He was diagraming venturi effect, but he did not call it as such. Justified. Seriously, if you are going to say something like this a day before, you need to have a solution. Where does he expect 5 million people to go to. If stretch it to make a problem of this magnitude, need to offer a solution.
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Quoting weatherwart:


I have a lot of pine trees on my land. That's my biggest fear with hurricanes. In fact, I'm seriously thinking of removing one too close to my house. They uproot or break off and if they land on your roof...


Pine trees snap..don't they. We had a lot of that north of Houston w/ Ike in the "Piney woods".
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Quoting 996tt:


Get it, but F2 and F3 tornados have hit down town high rises in Atlanta and Dallas and no real loss of life. These strikes were much more intense and worse than cat 1 winds and perhaps TS winds by the time it even gets there. Again, if he is going to scare everyone, where does he expect them to go.

If they were intellectually honest, they would mention that high rises have sustained direct hits by tornadoes and survived. They just conveniently leave out objective details and play on the subjective.


speaking of being honest, an F-1 tornado struck portions of NYC a couple years ago and busted out the windows of at least 2 high rises that I saw. Nearby in Scarsdale, NY an F-0 also busted out windows of high rises None of the sky scrapers in NYC would survive and F2 and definitely not an F3 tornado. If those high elevations manage to see 90MPH gusts, I guarantee you there will be windows busted.
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Quoting AllStar17:


I'm stunned! What is the NHC looking at???? LOL.

I have no idea.
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im sticking it out here in Atlantic City even with mandatory evac here..should be crazy
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878. bwat
Im still in shock how well Irene has held her own over the past 12 hours. Still pressures of 949mb with that kind of satellite presentation. She's a fighter no doubt.
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Irene does appear to be better organized....however, it wouldn't take much for dry air to be sucked into the core again. I can only hope that happens and weakens the storm quite a bit!
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Whatever happens with Irene, the weather channel, the 3 networks and et al are hoping it goes into NYC during the day! The nightmare for them all is that it haps during the dark of nite when they can not show what is happening(good for those ratings!).
Good luck to all in the area. zosimo-a former Jersey guy who spent many a summer at Sandy Hook.
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Quoting JohninRal:
Any word on conditions at Topsail?


Not there, but it isn't far from here. Judging by some of the pictures I have seen on facebook from there, horrible.

Roads flooded horribly.
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Quoting AllStar17:


I'm stunned! What is the NHC looking at???? LOL.



not sure
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Quoting AllStar17:
atmosweather:

I must say you are providing some very thorough and easy-to-understand analyses. Thank you!


I appreciate that and no problem! The information being given out tonight by some of the guys and gals here is invaluable.
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871. 900MB
Quoting ConnecticutWXGuy:


As I have mentioned several times, there has been no Nor'Easters (not NorEasterners) that have produced sustained high end tropical storm force winds/cat 1 hurricane force winds in NYC. While I don't doubt most skyscrapers will easily withstand this hurricane, I personally would not want to be in them. The winds will be increased one full category at those high elevations, for one thing.


Ha! You don't know how cheaply those new all glass towers were made. Believe me, if we get 90mph gusts the glass panels will be poppin like popcorn!
Member Since: June 11, 2006 Posts: 0 Comments: 684
Quoting RobDaHood:

Got it from more official sources, but same same.

Surge is a real concern here, even if the storm weakens because of the size of windfield and the volume of water that is moving.

Another thing...Many of the areas in the cone have had a lot of rain lately and saturated ground. I had the same thing here with Jeanne. Huge pines that had seen a lot of canes came down due more to lack of grip than the force of the wind. I'm expecting to see a lot of that with this storm.


I have a lot of pine trees on my land. That's my biggest fear with hurricanes. In fact, I'm seriously thinking of removing one too close to my house. They uproot or break off and if they land on your roof...
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Quoting atmosweather:


It is a long time but without the presence of more than just a partial inner eyewall she cannot intensify. It will still take some of those hours to develop a more intense and protected inner core so that dry air and shear will not continue to invade the circulation. If she does this very quickly then of course she could take advantage of that short window and ramp up.


Thank you for your analysis....keep up the work young blood! :>)
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Quoting Patrap:


I thought the yellow boxes were hail icons...What are they?
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Mission 30 "Kermit" about to intercept the center.
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865. 900MB
Quoting HappySkeptic:

Right click on the link to the .kmz file and save it to your hard drive. Someplace easy like "My Documents". Then click on it and let your computer choose Google Earth to open it (or open Google Earth and click "File" and "Open" and select the .kmz file). You should have all the Hurricane Hunter info your heart desires. Click on the "Weather" tab and you can turn on the satellite or radar too....


Thanks all! Got it. Looks like mild strengthening here. Let's see if recon picks it up.
Member Since: June 11, 2006 Posts: 0 Comments: 684
So far this season reminds me of Heisenberg's uncertainty principle--you know, the one that states that when we measure the momentum of a particle with increasing precision, we trade off some precision in measuring position and vice versa.

The models this year have been either good at "measuring" (predicting) the track of a storm, but not intensity, or they have been good at "measuring" intensity and bad at track. Take Emily. How long did she spend at 100% development probability without developing? Then when they lowered the probability slightly, she finally developed, but not as much as expected. However, the track was spot on almost the entire time.

Maybe tropical disturbances are like fundamental particles. Maybe the NHC should take the models' track agreement and throw out their intensity predictions, then take the intensity predictions from the outlier tracks.
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here in kure beach, i was wondering if someone could give me a time frame in which I should expect the strongest sustained winds and the highest gusts?
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LoL, I remember last year Earl was nearing the island and my science teacher was giving us a little lecture about hurricanes. I had to correct her TWICE, one for saying Earl was a Cat 1, and the other for saying Mitch was a Cat 3.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
91L update:

AL, 91, 2011082700, , BEST, 0, 276N, 613W, 30, 1014, LO, 34, NEQ, 0, 0, 0, 0, 1017, 100, 40, 0, 0, L, 0, , 0, 0, INVEST, S,
Member Since: November 8, 2009 Posts: 4 Comments: 13805
Quoting ShenValleyFlyFish:
What dude is this. I would bet those buildings have had more than this storm will dish up. Not downplaying storm, just believe that there have been NorEasterners with bigger wind punch than this will be. Storm Surge off the rivers may be another thing.


As I have mentioned several times, there has been no Nor'Easters (not NorEasterners) that have produced sustained high end tropical storm force winds/cat 1 hurricane force winds in NYC for an extended period of time. While I don't doubt most skyscrapers will easily withstand this hurricane, I personally would not want to be in them. The winds will be increased one full category at those high elevations, for one thing.
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Quoting Dennis8:


6-12 hours is a long time in Hurricane hours. I have been through 12 TS/ hurricanes and seen many a storm strengthen in the last 3 hours when they were NOT forecast too. 1970 Celia 80 mph storm ended up blowing the airport anemometer off at 161 mph..this lead me to my interest in wx an to getting my meteorology degree years later.


It is a long time but without the presence of more than just a partial inner eyewall she cannot intensify. It will still take some of those hours to develop a more intense and protected inner core so that dry air and shear will not continue to invade the circulation. If she does this very quickly then of course she could take advantage of that short window and ramp up.
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Wilmington animated WunderMap®

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Quoting Tazmanian:
AL, 10, 2011082700, , BEST, 0, 158N, 339W, 25, 1010, T


TD 10 has weakin


I'm stunned! What is the NHC looking at???? LOL.
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Any word on conditions at Topsail?
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Quoting mydiapersarefull:
From my WB bunker, I can confirm that Aaron Rodgers is looking pretty sharp...











Wrightsville? Be careful if that's the case... It was rough when I was out there about 3 hours ago and the storm surge at high tide will cause severe flooding around 5am
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AL, 10, 2011082700, , BEST, 0, 158N, 339W, 25, 1010, T


TD 10 has weakin
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atmosweather:

I must say you are providing some very thorough and easy-to-understand analyses. Thank you!
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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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