Hurricane Irene Prepares to Leave the Bahamas and Head for the US

By: Dr. Jeff Masters , 7:51 AM GMT on August 25, 2011

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As of 2AM EDT, Hurricane Irene was located at 24.2N, 76.0W, 105 miles east-southeast of Nassau or 760 miles south of Cape Hatteras. It was moving northwest at 12 mph with maximum sustained winds of 115 mph, making it a Category 3 storm on the Saffir-Simpson scale. Irene has a minimum central pressure of 950 mb. Hurricane force winds can be found up to 70 miles from Irene's center, and tropical storm force winds can be found out to 255 miles from the storm's center.

Hurricane warnings are in effect for all of the Bahamas. Hurricane and tropical storm watches will likely be posted for the Carolina coastlines later this morning. At this time, Dare County Emergency Management has issued a mandatory evacuation order for all visitors in their county. Dare County Schools will also be closed Thursday and Friday.

Satellite Views
Figure 1 is the infrared satellite image of Irene at 135EDT. The convection is a bit unbalanced around the storm center, which is going to cause Irene to wobble like an unbalanced clothes washer (Analogy courtesy of Angela Fritz) over the next few hours. At the time this image was taken, the convection around Irene's center appears to be getting more vigorous, as cold cloudtops are starting to increase around the storm center. This is important to note because microwave satellite imagery from Wednesday evening suggested Irene was starting an eyewall replacement cycle. Figure 2 shows passive microwave imagery from a Air Force DMSP polar-orbiting satellite. The two concentric green/yellow bands in the image suggest that two eyewall features are present in Irene, and Hurricane Hunter observations confirm this. This has important consequences for Irene's intensity, because in an eyewall replacement cycle, as the inner eyewall weakens, the storm's intensity drops. However, once the inner eyewall is gone, and the outer eyewall contracts to replace it, the storm intensity will increase again.


Figure 1 IR satellite view of Irene taken at 113AM EDT, August 23, 2011


Figure 2 DMSP F18 microwave overpass of Irene at 824PM EDT, August 24, 2011. Image courtesy of the Naval Research Laboratory

Track Forecast

Irene is forecast to move to the northwest, passing over the northwest Bahamas by Thursday evening, then curving to the northeast. Irene then makes landfall in the US near or at the Outer Banks Saturday afternoon, then traveling along the mid-Atlantic coastline of the US. Sunday, Irene may make secondary landfall anywhere from New Jersey to Long Island and the southern New England coastline. In my opinion, New York City may be significantly impacted by Irene. It is also important to note that the windfield of Irene is expected to be large, affecting areas distant from the immediate track of Irene's center. Tropical storm forces winds are expected to be found out to at least 150 miles away from Irene's center on Friday afternoon.

NHC is forecasting for Irene to become a Category 4 storm (winds faster than 130 mph) by Thursday morning. As Irene moves northward into cooler water, the intensity is expected to drop slowly to a Category 2 storm before making landfall in the Outer Banks.


Figure 3 Official track forecast of Irene at 2AM EDT.

Forecast models and today's planned flights
The different forecast models are still in fairly good agreement about Irene's track through the Bahamas and along the east coast of the US. The 00Z GFS run is in close agreement with the 12Z ECMWF run, but the 00Z ECMWF run (shown in figure 4) is continuing the ECMWF's trend of shifting the track westward with each run. NHC forecasters have been placing emphasis on the ECMWF's forecast track when making their forecasts for IRene, so it is possible that the NHC track will shift westwards at the 5AM update.

Looking at the plan of the day valid for today, it will be a busy day for airborne reconnaissance. Three flights for the Air Force hurricane hunters, two flights for the Gulfstream IV (Gonzo), and two flights for NOAA 42, a WP-3D (Kermit). They may have to give NOAA a littering permit for all of the dropsondes used to monitor Irene and her environment, but the forecast improvements they generate are worth the effort.


Figure 4 Plot of the maximum sustained winds in mph over the next week from the 00Z ECMWF forecast.

Impacts

Hurricane force winds will arrive in the northwestern Bahamas today. Storm surge near the center of Irene will be 7-11 feet above tide level. The Bahamas can expect 6-12 inches of rain over the next day or so, and it looks like the Turks and Caicos islands will receive a total of 6-12 inches from Irene. Large, swells from Irene will start landing on the southeastern US coastline later today. Please don't go in the water, as these swells can cause dangerous rip currents. Dr. Masters has catalogued the worst-case storm surge surge scenarios as a function of storm intensity here.

In my opinion, people living from the Carolinas to Cape Cod should pay close attention to Irene and prepare for a wide range of impacts. I think that there is a 75% chance of Irene's secondary landfall will be somewhere between JFK airport and Cape Cod. That said, Irene's size will cause significant impacts for people living far from it's center.

Dr. Masters will have a new blog entry this morning, and Angela Fritz will be covering the afternoon. I'll be back on third shift tonight.

Thanks for reading,

Dr. Rob Carver

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"They may have to give NOAA a littering permit for all of the dropsondes used....."

And people have suggested that Dr. Masters does not have a sense of humor. Crow is now being served, in the main dining room.

On the weather front, I am happy to report that Houston, yes, the one in Texas, has received a modest amount of rain since yesterday evening. There is a chance for this to happen again today.

I hope that everyone that may be in the path of Irene have already taken precautions. Considering that this is likely to be more than an evening thunderstorm, I hope that those that to need to evacuate have already made their plans to do so. Patrap and KEEPER are two, along with others, that have offered to us excellent information for us to remain safe and to help minimize our damages.

Stay safe, everyone. This may be a motley crew but, I have learned much from each of you. Thinking back, and thanks to presslord, I am now aware that there are TWO Carolinas. I just somehow never visualized that. ... Seriously, I hope to see you all throughout the remainder of the season, and beyond.
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945. DFWjc
Quoting 69Viking:


NOOOO, say it isn't so! If Irene hits 77W there will be a lot of Crow eaters on this blog!


Yep...I'm closer to cashing in my prediction...Still got +/- 150 miles off the coast of Florida...
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Quoting zoomiami:


Great link -- but perhaps what I should have said was that according to the reports on the news at 11:00 on Friday night there was no need to worry about the storm as it was turning away from us.

That changed on Saturday morning.


Yes, only Norcross was sounding the alarm. We know now where to get our information from, the source.
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Quoting snotly:
so I was thinking in investing in hotel chains, plywood, batteries, chain saws, backup generators and survival supplies, when would be a good time to get in the market?


December 12, 2012. Best of luck with your new venture.
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Quoting MississippiWx:
She got pretty close to South Florida...



And that's why everyone last night was worried.
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Quoting Fotograffa:


I was on the Cape for Gloria...seems we got really short notice for it. I don't remember the details. We didn't have wall to wall weather outlets like we do now. They issued the watch and a half hour later it was a warning. The storm came the next afternoon. We had 110 mph sustained in Hyannis but it was a short storm...I was in blizzards there that lasted a whole lot longer and produced more damage than Gloria.


Having also been in Hyannis for Gloria, I agree, it *was* a short storm, but only because it unexpectedly veered inland and we were spared the brunt of it.
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Only in Sarasota could a massive hurricane improve our weather. 15-20mph breeze with humidity backing off a bit. Feels like a little sample of fall. Good luck and be safe to everyone in the path of Irene
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Quoting snotly:
nearing 77 west...


NOOOO, say it isn't so! If Irene hits 77W there will be a lot of Crow eaters on this blog!
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And Florida has still not issued at least a Tropical Storm warning for its East coast?? Are they nuts or what? Sorry, but with a storm this big, the WHOLE eastern seaboard should be on alert!!
Renata in Barbados <
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I can't believe it!!! The local officials in Atlantic City are talking about possible evacuations..OMG!!! That's never happened that I can recall. In the paper today they also saying to prepare for multi day electric outages. In years gone by they didn't talk about storms on the way. They're NOT putting their heads in the sand this time around.
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Mississippi,

Hey, good morning. So what do you think of Irene's EWRC? Do you think she is almost finished with it after that bit of dry air ingestio, and if so do you think she will reach Cat 4 before landfall on the OBX?
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She got pretty close to South Florida...

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I have to disagree..I watched WWAY this morning and they are minimizing this storm..people I have spoken with are thinking only minor impact and not thinking of what could happen by a deviation of 40 miles..


If you were here for the last major which was Fran in 1996 (Floyd was bad but mostly a flood event), you'll remember that we had Bertha first. Ton of rain, overwash, and all those pine trees got loosened up.
That set the stage for the Fran disaster.
We've been in a drought and haven't had any storms push through here this year. Sure, there'll be wind and rain, but even at a Cat 3...this wouldn't be a
Fran-like catastrophe...unless it came ashore somewhere in MB and we got the east side....

Too much hysterics!
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Quoting drj10526:


i do but a ski boat. I am pulling it on friday. It gets banged up from a normal storm, not chancing it with this type of storm.

On a side note, the amount of people up here that have no idea whats about to happen is amazing. My neighbor had no idea and started taking in her potted plants when i told her. She just assumed it was happening today since i told her this morning. A lot of people will be caught unprepared. Us northerners just dont get it yet.

Northerners don't get it and Floridians are idiots because they do... what a messed up world we live in
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so I was thinking in investing in hotel chains, plywood, batteries, chain saws, backup generators and survival supplies, when would be a good time to get in the market?
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930. HiWay
Quoting wayfaringstranger:
Just an observation, just exactly how much colder are the waters up in the northeast?

We start out a lot of blogs on global warming and regardless of where your stance is on gw, the fact is that we have experienced several hot summers even into the north east.

My thoughts are that Irene may have plenty of warm water when approaching the NE. I think its a pretty thin argument to claim that just because of region that the water will be presumably colder.


Not as cold as they should be. Dr. Masters yesterday in one of his posts referred to an anomaly this year extending significantly farther up from the gulf stream keeping waters warm enough to sustain Irene (not strengthen, but not kill her either).
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Quoting HCW:


You need to customize that thing :)



Where'd you get your shape files? That was the best one I could find...
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Quoting FLWeatherFreak91:
That's because you're looking at the wrong layer. This is the correct steering map for a storm as deep as Irene:


I believe he was talking about TD10(90L)
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Quoting ecupirate:


Chainsaw! They are hard to come buy after a storm.

I strongly reccomend one if you have trees in your yard.


I was glad I had a chainsaw in 95 when Hurricane Erin went through our area. Without chainsaws we would have never made it out of our neighborhood for a couple of days, trees that hadn't see a Hurricane in over 20 years came crashing down over the rural streets. Chainsaws are very handy after a Hurricane!
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Quoting nash28:


Bah. Not a very large gap for Irene to shoot through... Looking more and more likely she gives the north coast of SC a very close shave.


yea, the RUC 24h forecast pretty much gives her no option but right toward Little River, I'll be glued to this for the duration, except brief jaunts out to watch the swell
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Quoting Abacosurf:
These little islands handle storms much better than the U.S. IMO. The sense of community is what makes the difference.

It's not every man for himself.

There was only one death from Floyd in all of the Bahamas. That had 155 MPH winds when it hit.
is elbow cay evacuated?
Member Since: September 11, 2010 Posts: 1 Comments: 4723
924. HCW
Quoting charlottefl:
Irene's eye wall beginning to show up on Miami long range radar 191 nautical miles from the radar site. 219 Statue Miles.

Photobucket">


You need to customize that thing :)

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923. Relix
So... any clues on when TD10 will feel that weakness? I honestly don't see anything in the layer to identify one =|.
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Just an observation, just exactly how much colder are the waters up in the northeast?

We start out a lot of blogs on global warming and regardless of where your stance is on gw, the fact is that we have experienced several hot summers even into the north east.

My thoughts are that Irene may have plenty of warm water when approaching the NE. I think its a pretty thin argument to claim that just because of region that the water will be presumably colder.
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921. hamla
strong>Quoting bythegraceofgod:
Living in South Mississipp and having gone through many hurricanes I won't feel comfortable until Irene gets north of Georgia. From experience another supply to have on hand is rock salt. Don't know if anyone has mentioned it but it helps in the ice chest. Keeps things much colder. Kids juice boxes will even freeze in that stuff. Also any gas grill will work to cook just about anything on. I keep mac and cheese, hamburger helper, canned crab and salmon for crab cakes or salmon patties, and of course canned food. I try to keep at least a week of food and water for us. With Katrina we were without power for a week. You have to remind yourself to drink lots of water cause you will be sweating cleaning up the mess and can dehydrate quickly. Also, good old pepto bismal and immodium for tummy upsets which are bound to happen. And not only will ATMs not work but most banks will be out of service if they have no electriciy so get all the cash you can beforehand.


AMEN
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Quoting nrtiwlnvragn:
794. zoomiami

While the location of the center crossing the coast was not well forecast, South Florida was under a hurricane watch 36 hours before landfall and a hurricane warning 21 hours before landfall.


Link


Great link -- but perhaps what I should have said was that according to the reports on the news at 11:00 on Friday night there was no need to worry about the storm as it was turning away from us.

That changed on Saturday morning.
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Quoting nash28:


Thought he was talking about Irene.

My mistake:-)


And that should say 1000, obviously. Lol. I never proof read my posts.
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Wect News twitter account- http://twitter.com/#!/wectnews
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Quoting MississippiWx:
Relix is talking about TD10...not Irene.
Yep my bad. Should have read the entire post.
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Watch the chainsaw though if you're a newbie (or anybody, for that matter). Injuring yourself will not help the situation!
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she might stall for alittle bit right after she leaves the bahamas
Member Since: September 11, 2010 Posts: 1 Comments: 4723
Quoting MississippiWx:


How? That's the 100-1010mb layer.


Thought he was talking about Irene.

My mistake:-)
Member Since: July 11, 2005 Posts: 190 Comments: 16972
Quoting hydrus:
Gloria was bad for that area too...Fast mover though..


I was on the Cape for Gloria...seems we got really short notice for it. I don't remember the details. We didn't have wall to wall weather outlets like we do now. They issued the watch and a half hour later it was a warning. The storm came the next afternoon. We had 110 mph sustained in Hyannis but it was a short storm...I was in blizzards there that lasted a whole lot longer and produced more damage than Gloria.
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Relix is talking about TD10...not Irene.
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Quoting nccanewatcher:
New Hanover County is now under a voluntary evacuation. State of emergency declared for tomorrow at 6AM. Shelters open at 6pm Friday. They will adjust as needed.


Wow im going to go out and get supplies soon before it becomes a mad house. Link?
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Quoting JoseMaria:
This hurricane is right in the middle of those little islands which are no higher than maybe 20 ft above sea level - where are all the people sheltering? I have not heard any news coverage about the human loss and/or material loss regarding to this disaster.

Irene just passed Puerto Rico about five days ago and we still have thousands without electricity and water, even in shelters because they lost their houses due to the tropical storm winds. It was not even a hurricane when it went over us!
These little islands handle storms much better than the U.S. IMO. The sense of community is what makes the difference.

It's not every man for himself.

There was only one death from Floyd in all of the Bahamas. That had 155 MPH winds when it hit.
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908. Relix
AAAH! I meant about TD10 not Irene. Sorry about that hahaha!
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Quoting nash28:
Wrong steering layer Relix.


How? That's the 1000-1010mb layer.
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906. Relix
Quoting nash28:
Wrong steering layer Relix.


It's the 1000-1009mb steering layer. There's no way that TD has a pressure less than 1000 :P!
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Irene's eye wall beginning to show up on Miami long range radar 191 nautical miles from the radar site. 219 Statue Miles.

Photobucket">
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New Hanover County is now under a voluntary evacuation. State of emergency declared for tomorrow at 6AM. Shelters open at 6pm Friday. They will adjust as needed.
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Quoting 69Viking:


Still a Westerly push going on from that Altantic High at least until Irena gains some more latitude.


Gonna be a close shave for these parts I believe. I mean even at 78W. That's only 120 miles.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
nearing 77 west...
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Quoting Relix:

Ill be honest... I don't see any weakness at the moment.

That's because you're looking at the wrong layer. This is the correct steering map for a storm as deep as Irene:
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When is the next HH flight planned for?
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899. MahFL
Can anyone explain why Irene keeps having clouds blow up near the center and they expand WNW or NW towards Florida ?
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898. 900MB
Quoting Jax82:
looks like she's losin' her cold cloud tops at the moment.


Looks that way. She's got 36 hours to find herself, build and peak.
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Quoting Browardbarometer:


If I remember correctly, Don Noe (CH-10 met), told everyone that Andrew was not gonna be a S. Fl hurricane on Friday evening prior to landfall. Not one of his finest moments!


I remember boarding up in Stuart b/c they weren't sure where Andrew was going to hit--and by the next morning, it would be too late to do anything about it.

Then there was David in 1978--on the battery-powered radio they kept saying it was 100 mi. due East of Miami--when it was RIGHT on top of us.

My how things have changed....as long as they make the projected turn................
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Quoting WxLogic:
Turn coming up:



Still a Westerly push going on from that Altantic High at least until Irena gains some more latitude.
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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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