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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996. MahFL
Quoting wxobsvps:
RUC +22 ... 10m wind





Er that looks a bit closer to FL than forcast.....
Member Since: June 9, 2004 Posts: 0 Comments: 3266
Quoting Klolly23:
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


All of Florida should have a pretty good weekend weather wise once Irene passes. We should get some nice Northeast breezes to break the heat a little!
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Looks to beginning the move to the North, but maybe just a wobble.
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Quoting HCW:
Irene Flood pic from P.R


De ja vu--last night!
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Quoting mydiapersarefull:
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!


I have been here since Gloria of 85..I know hurricanes left and right..we have had rain every day this week..A category 3 wind field is nothing to sneeze at even if we have been in a drought..it will still knock down trees and cause damage..the ground is not cement..
Member Since: August 19, 2006 Posts: 13 Comments: 14420
Quoting renats:
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 <
Actually we have a Tropical Storm Warning have since 8am
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987. HCW
Irene Flood pic from P.R

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Quoting Chucktown:


Its forecast to go west of 77 - visible with shows Irene right on track of NHC - click on trop points

Link


Based on that link she's going to come close to 78W.
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NYC Hurricane evacuation map.

Click for full-page PDF:

nycevac


Hurricane evacuation finder here.
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Quoting islander101010:
stayed in hope town for 10 days may 10yr ago up early to be early to bed. mosquitos were bad. hope the best for you all
I am not there right now but the house is storm proofed as can be.

Looks like it is going to intensify right on their heads unfortunately.
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982. Jax82
Close up Visible of Irene. Looks like the eye may pop out soon.

NASA GOES
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Quoting Chucktown:


Its forecast to go west of 77 - visible with shows Irene right on track of NHC - click on trop points

Link


It's wasn't forecast to go West of 77 early yesterday or two days ago. The NHC changes their forecast tracks every so many hours. My point was yesterday several on this blog said it wouldn't make it to 77W and all I'm saying is they'll be eating crow soon.
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Quoting 69Viking:


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!



yes ... erin i think was only a cat 1 .. but i remember tons of trees down .... chainsaw heaven
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979. beell
On a positive note, we may see some fairly strong southwesterly shear values (40 knots or greater) over the western half of Irene as she approaches the NC coast.

06Z GFS 200mb @72hrs
click to enlarge

Member Since: September 11, 2007 Posts: 141 Comments: 16204
978. MahFL
Quoting MississippiWx:
She got pretty close to South Florida...



She's going to get closer still.....
Member Since: June 9, 2004 Posts: 0 Comments: 3266
Looks to me like Irene is going almost due north now, but I suspect the NHC will call in NNW for awhile. We'll see what they say in a few minutes.
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976. HCW
There is no need what so ever to issue any watches for FL based on the current track


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Quoting Chucktown:


Its forecast to go west of 77 - visible with shows Irene right on track of NHC - click on trop points

Link


Correct. Anything beyond 79W though and heartburn begins...
Member Since: July 11, 2005 Posts: 190 Comments: 16972
Quoting wayfaringstranger:


Wow. Look, NC / SC residents should prepare now. It's pointless to assume.

I read this morning from a very reliable source that the track will shift some west before turning more NW. That should be taking place now or by 13:00 EST.

And although this shift west will not be much, when given proximity of where Irene will make landfall in NC, its just way too close to assume that SC wont feel any residual TS winds. Wilmington and the Cape should be making preparations.


Thanks!
Member Since: August 19, 2006 Posts: 13 Comments: 14420
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Quoting Abacosurf:
Some may leave but most stay.

They have plenty of shelters as do all of the out islands.

People build very well in the Abacos. They don't have shacks with tin roofs...lol

They are built strong and usually a ton of tongue and groove on the interior which bonds these homes together much more than drywall.

The new roof of choice has been the bermuda roof with many putting an epoxy and fiberglass cloth on to boot.

stayed in hope town for 10 days may 10yr ago up early to be early to bed. mosquitos were bad. hope the best for you all
Member Since: September 11, 2010 Posts: 1 Comments: 4320
Quoting DFWjc:


Noisy little buggers aren't they...I have to deal with Sandpipers, hate those damn birds!!


Ah, but these are eatin' crows--for you guys and your predictions!
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Quoting SPLbeater:


Looks a little more symetrical then it did a few hours ago, hanvt seen anything about the EWRC being complete, but am seeing a dip in the center!


I'm not going to be juvenile and say...


But Irene is flashing us!
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Quoting nash28:


Gonna be a close shave for these parts I believe. I mean even at 78W. That's only 120 miles.


ummm...yeah...that is the difference between TS gusty day and sustained winds...if i am not mistaken, didn't we have this discussion yesterday about her passing 77W... ;)
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Quoting hydrus:
Gloria was bad for that area too...Fast mover though..


I remember Gloria. It didn't do much. But Bob, Bob was scary. So many old oak trees down, I was surprised at how many fell right next to houses, or cars or buildings, and realized how lucky we were.

It took weeks to get the power back up, and anyone with a chain-saw made a ton of money.
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Quoting MississippiWx:
She got pretty close to South Florida...



Wow. Look, NC / SC residents should prepare now. It's pointless to assume.

I read this morning from a very reliable source that the track will shift some west before turning more NW. That should be taking place now or by 13:00 EST.

And although this shift west will not be much, when given proximity of where Irene will make landfall in NC, its just way too close to assume that SC wont feel any residual TS winds. Wilmington and the Cape should be making preparations.
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Quoting Ryuujin:
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?


Morning!

I think she's about halfway done with it, maybe a little more. If we look at the MIMIC product from CIMSS, you can see that she is still open to the south. Of course, this loop is 3 hours old now and she is probably a little closer than this shows.

As far as dry air goes, you can see that on this product as well. The radar loop I posted a few posts back also shows the dry slot on the west side as well.

Anyway, when the EWRC is complete, I see no reason why she can't become a Cat 4. The only limiting factor is dry air, and she has been able to mix that out before her EWRC took place.

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From FEMA situtation reports





Hurricane Irene
As of 5:00 a.m. EDT, August 25, Hurricane Irene was located about 80 miles east-southeast of Nassau and about 735 miles south of Cape Hatteras, North Carolina, moving to the northwest at 12 mph.

Maximum sustained winds remain near 115 mph with higher gusts. Hurricane force winds extend outward 70 miles from the center and tropical storm force winds extend outward up to 255 miles. Irene is now a category 3 hurricane. Some additional strengthening is forecast during the next day or so.
Irene is expected to produce rainfall accumulations of 6 to 12 inches across the Bahamas.

A Hurricane Watch has been issued for the North Carolina Coast, north of Surf City, NC, to the North Carolina-Virginia border including the Pamlico, Albermarle, and Currituck sounds.

A Tropical Storm Watch is in effect for north of Edisto Beach, SC, to Surf City, NC.
Surf and swells generated by Irene will begin affecting portions of the Southeastern Coast of the U.S. today. These swells are expected to cause life-threatening surf and rip current conditions.

The core will move over the northwestern Bahamas today. A turn toward the north-northwest and then toward the north is expected today and tonight and pass well offshore of the East Coast of Central and North Florida tonight and early Friday.
Storm surge in areas of onshore flow near the center of Irene expected. A dangerous storm surge will raise water levels by as much as 7 to 11 feet above normal tide levels over the Bahamas. Near the coast, the surge will be accompanied by large and dangerous waves. (NOAA, NHC)

Mandatory evacuations will be in effect at 5:00 a.m. EDT on today for Ocracoke Island, NC. Voluntary evacuation for New Hanover County (Wilmington) will begin at 6:00 a.m. EDT today. Additional NC counties are expected to issue voluntary and mandatory evacuations today.

The State of Connecticut has initiated a pre-activation of the Emergency Operations Framework procedures.

Territorial Response
Puerto Rico
PR has received approximately 22 inches of rain.
One reported fatality: a woman died as a consequence of a river overflowing its bank in Carolina, PR.
Over 93 houses were damaged or destroyed as a result of the impact of Irene.
Twelve shelters open with 528 occupants.
Approximately 116,000 customers are without power as of 11:00 p.m. EDT, Aug 24.
Approximately 70,000 customers are without water.
All ports and airports are open.
There are 7 medical facilities (1 hospital and 6 diagnostic treatment centers) on generator power.
About 500-800 citizens in Guayanilla Municipality, 300 in Toa Baja, and 200 in families in Ponce, are evacuated due to flooding.
Estimates of up to 4000 citizens may be affected as flooding area grows over next few days.

U.S. Virgin Islands
95,762 customers without power throughout the Island.
Twenty-five percent of customers without water are expected to have their service fully restored today.
All ports and airports are open.

Significant National Weather
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Morning All.

Irene appears to be stumbling a bit.
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961. DFWjc
Quoting Landfall2004:


Hey, I've got a good supply of crows in my yard again--just like with Emily. Very strange!


Noisy little buggers aren't they...I have to deal with Sandpipers, hate those damn birds!!
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Quoting TallyMike:


MAybe kind of silly but I move some my larger tools such as a crowbar, ax and chainsaw into the house in case we have to dig out. Lots of big trees in our yard.


Not silly at all. You know your surroundings better than anyone else and if digging out is a possibility then by all means keep those things inside.
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Quoting Landfall2004:


Hey, I've got a good supply of crows in my yard again--just like with Emily. Sounds like they may be need again. Very strange!
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Quoting 69Viking:


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


Its forecast to go west of 77 - visible with shows Irene right on track of NHC - click on trop points

Link
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If you live in eastern Long Island or near the RI/CT border, remember the storm will be stonger than the models sugest because the Hurricane would be further from land before it hits you.
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Quoting islander101010:
is elbow cay evacuated?
Some may leave but most stay.

They have plenty of shelters as do all of the out islands.

People build very well in the Abacos. They don't have shacks with tin roofs...lol

They are built strong and usually a ton of tongue and groove on the interior which bonds these homes together much more than drywall.

The new roof of choice has been the bermuda roof with many putting an epoxy and fiberglass cloth on to boot.

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Satellite shows shes going north, radar shows shes going wnw (then seemingly came to a complete stop the last few frames). Where is her center really at right now and where is she moving, if at all?
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Quoting DFWjc:


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


Hey, I've got a good supply of crows in my yard again--just like with Emily. Very strange!
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Quoting CarolinaHurricanes87:


Wow im going to go out and get supplies soon before it becomes a mad house. Link?


If voluntary evacuations have been issued the madhouse has already started! I always make it a point to buy my supplies before they start evacuating people. Usually long before they issue watches and warnings too. Good luck!
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Quoting Zaphod:
Add to the list a few pairs of good gloves (leather) and contractor trashbags. Clean-up will often take days, and involve metal, wood, and glass with sharp edges.

If you're up east, you still have time to order LED headlamps, dried food, water filters, camp stoves, chlorine tablets, and so forth on-line from REI. If you don't need them for the 'cane, use them for a camping trip this fall.



MAybe kind of silly but I move some my larger tools such as a crowbar, ax and chainsaw into the house in case we have to dig out. Lots of big trees in our yard.
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Looks a little more symetrical then it did a few hours ago, hanvt seen anything about the EWRC being complete, but am seeing a dip in the center!
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Quoting WeatherfanPR:



Hey, you are using my Avatar !!!


Well look at that. Hmm... I guess I'll have to find a new one. I just googled "weather avatar." :)

OK, new one awaiting approval. Don't want people to think I am impersonating you.
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From the satellite loops looks like she is going more north now Link
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"IRENE!, I say again, IRENE!", Blackhawk Down.
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947. Vero1
Quoting palmbaywhoo:

Northerners don't get it and Floridians are idiots because they do... what a messed up world we live in
Now they will see what we have to deal with all summer after they leave in April.
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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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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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