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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Should my Family in Fayetteville NC be worried?
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Quoting tpabarb:


Well crap! And I still think Grandpa should leave Atlantic Beach.

Thanks guys for answering my question earlier. Surf City is pretty close so I'm betting that Hurricane Watch will expand.


Local weather guy told me on facebook that if it shifts even 50 miles west that our conditions in Wilmington would be much worse.


Just remember, Irene can't read the weather maps or even knows what a "Cone" is! Neither could Charlie, the maps all said a Tampa Bay hit....many folks here evacuated south and just hours from when he was supposed to hit Tampa, he up and decided to take a hard right and hit Punta Gorda 100 miles to the south! These storms can be wily things and just do what they want!!
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Quoting butterflymcb:


I also want to know the answer to that question...

What is that???
I wonder if it could have picked up on the HH flying out of the Virgin Islands.
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Quoting nash28:


Right. You can clearly see the weakness in between the two highs. You have the Bermuda High out in the ATL and the Rockies High centered over TX. The U-shape over the Great Lakes is the trough which is creating the weakness and the lane for Irene to travel up through..

The only question unanswered is whether or not this trough will erode the periphery of the ATL High enough to turn Irene away from the coast.


So far it seems like the CONUS high has been the one willing to give ground for the trough.
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they forgot to clean the lens.

Quoting Skyepony:
What is that on the SSE side there at the end of MIMIC?
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Quoting ecupirate:


Government secret project to push Irene into the carolina's in order to save the North East....

LOL What are they using, a ray gun?
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Quoting yorkcova:
not a nice forecast to wake up to here in tidewater. someone could make a killing with a truck full of generators.


Me neither and I am 50 miles or so west of you in Richmond. All local tv stations WTVR WRIC and WWBT have you getting 60-70 mph winds maybe a brief period of hurricane force winds. Here in Richmond we're expecting 40-50 mph winds.
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I'm digging the blog's vibe this morning... people coming to grips with FL getting passed.

Time for a mojito.
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Quoting MahFL:


I guess it shoots that small gap then towards NC ?


Right. You can clearly see the weakness in between the two highs. You have the Bermuda High out in the ATL and the Rockies High centered over TX. The U-shape over the Great Lakes is the trough which is creating the weakness and the lane for Irene to travel up through..

The only question unanswered is whether or not this trough will erode the periphery of the ATL High enough to turn Irene away from the coast.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
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Quoting whepton3:


That high over the Atlantic is a bull... no wonder everything is creeping west.
That is what I was looking at this morning and wondering how they expect TD 10 to go WNW. High is very strong and far west which if I am not mistaken should send it W or slightly WNW.
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Quoting whepton3:


That high over the Atlantic is a bull... no wonder everything is creeping west.


GoM ULL isn't helping either. She should get more entrenched in the western periphery flow pretty soon (24hrs?)... problem is the flow is due north.
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484. HCW
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Quoting kshipre1:
anyone have a link to see future waves coming off of Africa?

I know this is a good thing but for goodness sakes!!.... it is approaching September and only 1 yellow circle on the map!

href="http://oiswww.eumetsat.org/IPPS/html/MSG/IMA GERY/IR039/COLOR/FULLDISC/index.htm" target="_blank">Link
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482. MahFL
Quoting HarryMc:


First step is to imagine that's a snapshot, sort of like standing beside a highway and taking a picture of traffic. Everything on it is moving in real time and it takes other charts to know what's really happening. A little complicated.


I guess it shoots that small gap then towards NC ?
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This came through a couple of hours ago, so apologies if someone already posted it here--The Tribune in Nassau is reporting that "a weather station in Arthur's Town, Cat Island has recorded a gust of 143 mph" this morning. Yikes--so some of those peak winds were reaching the surface after all.
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480. IMA
Quoting Skyepony:
What is that on the SSE side there at the end of MIMIC?


Pretty sure they're those super-secret weapons used to destroy hurricanes. Damn, there goes my security clearance!
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Quoting OuterBanker:
Good morning from the sunny Outer Banks (OBX) of NC. The way I see it using the GRILL forecasting method, it I situated my grill on a N/S axis, I'm ok, but if I turn it E/W, than than I am in the latest path. fyi, no locals I can find are leaving at this point. They have made evacuation mandatory for our guests (+ or - 200K), but the locals are staying put, as it is forecast as a CAT 2. Would you go? Storm surge is 6 to 8 feet, we are a sandbar, but a fairly hilly one with maritime forests, CCC dunes, and some well known areas,which seem to flood often. So would you go? I need to make the call by 11:00 am, if I am to get help leaving. I am leaning toward staying.


A large category 2 storm,such asIrene, can push more water over 8 ft,like maybe 10ft or more. I would leave and go inland somehweres, maybe Asheville NC to be safe
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Quoting Maryland1:
Good mid morning blog. We're getting close to finding out some things. Any more westward and the Northern NC coast and the Delmarva penisula gets a historic storm. Not to mention DC/Balt. That would help our Northern friends a bit and knock down the second strike. Either way, this is not a good story. I think we will be remembering Irene for a long time. Today is get things together day, tomorrow will be crazy.

Cat 5: You've been on this well for the last few days, still betting on the western landfall.

That's my thinking still. I think Myrtle Beach is out of the woods for a direct landfall, but hurricane force winds there along the coast are definitely not out of the question. At the very least, hurricane force gusts are possible there as she makes her way up the coast.

Still alot of time before all of this, and alot can change. But at the moment, anywhere between Wilmington, NC and Morehead City, NC is where I think approximately she can make a direct landfall. Until I see an almost due poleward motion within the next 12 hours, I would not be surprised to even see the NC/SC get a direct hit, as Nash alluded to earlier.

I say if she get's as far west as 78 degrees, that's a very bad sign for the NC/SC border. We won't know that for another 12-18 hours though.
Member Since: August 17, 2010 Posts: 21 Comments: 6939
Quoting Jax82:


I would listen to local authorities. I would also ask myself this question. What if Irene becomes stronger than currently forecasted, are you willing to take that chance? And are you ready to be trapped on an island for days without power, and unable to leave if the transportation network fails?


Local hurricane authorities must be lawyers with second jobs. All they say about the "year-rounders" are you should make your preparations now. Preparations to stay? Preparations to leave? Preparations to protect property? They are not offering any specific guidance?
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From the Turks & Caicos:

"After guessing at what Irene may have been up to, the story can be told. It was definitely 'come close, let's touch.'

The islands in the chain took a lashing from the winds and stinging rains of Irene yesterday, last night and most of the morning. From about 1:00 this morning until about 5:30, Providenciales was pelted with strong hurricane force winds and rains coming down in sheets. One report is that someone on the ridge in the South Dock area recorded a wind gust of around 116 mph (shortly after 8 pm).

Once the winds started out of the east in the early hours of the morning, the water got piled onto the Caicos bank and began pouring over the southern coast of Providenciales. Sea water covered the road near the bypass to Five Cays in the vicinity of SmithCo. gas station and the round-a-bout to Five Cays, cutting off passage to Five Cays, South Dock, Sapollida Bay and Chalk Sound. Flood waters covered the entire downtown area and flowed west into Kew Town. The canal adjacent the road to Discovery Bay and Cooper Jack Hill, overflowed its banks and hid the sections of the road from view. Venetian Road, in the area of South Side Marina, was also covered by sea water pouring in from Lake Sahara (central Turtle Tail). Sea water in the Caicos Marina and Shipyard area breached the bank and flowed into the Long Bay Hills Canal. Most of the usually dry ground in that area was under water. It is estimated that the storm surge must have been 6 feet during high tide.

Several roads are flooded with up to 18 inches of water (water was as deep as 24 inches in some areas). In the Long Bay Hills one section of the the road looked like a canal of approximately 500 feet in length. There is one confirmed report of severe damage to a roof in the Five Cays area. Shrub and twigs are scattered along some roadways and trees are down in some sections of the island. There are no reports of significant damage to buildings and, at this time, there are no reports of injuries sustained as a result of the hurricane.

Amazingly, a significant portion of the island had electricity, telephone, cable and internet access throughout the strong winds of Irene. Residents in Blue Hills, on the northwestern coast of Providenciales, were without electicty since yesterday afternoon. Portions of Five Cays were also without electricity since yesterday. Some residents are now reporting that city water is unavailable.

The flooding associated with Irene will probably be the thing that will be remembered for a while. North Caicos reported heavy rainfall throughout the passage of Irene and rain continues at the time of writing this report - a few trees are down across the island and this may be the case for Middle Caicos as well. Grand Turk reported very strong winds and rain. Flooding is also an issue on Grand Turk - there are a few trees down but no major damage to homes and other buildings. Reports are that some residents on Grand Turk spent the night without electricity as a result of the strong winds.

A video link of the situation on Providenciales will be made available later this afternoon.

I trust our friends and families in the Bahama islands have taken the necessary precautions and are well prepared for Irene's visit.

Good night Irene. It's time to go!"

Link
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Quoting OuterBanker:
Good morning from the sunny Outer Banks (OBX) of NC. The way I see it using the GRILL forecasting method, it I situated my grill on a N/S axis, I'm ok, but if I turn it E/W, than than I am in the latest path. fyi, no locals I can find are leaving at this point. They have made evacuation mandatory for our guests (+ or - 200K), but the locals are staying put, as it is forecast as a CAT 2. Would you go? Storm surge is 6 to 8 feet, we are a sandbar, but a fairly hilly one with maritime forests, CCC dunes, and some well known areas,which seem to flood often. So would you go? I need to make the call by 11:00 am, if I am to get help leaving. I am leaning toward staying.


Really bad call. Storm will be stronger than Isabel, which tore things up. I spend a lot time there and have a book about the Ash Wenesday storm on my desk, which nicely lays out the surge dilemma of the beach cities. If you've got a choice, leave unless you are in the pines above Seascape. And get used to the idea of two weeks without power or running water.
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Quoting wxobsvps:
Current steering. Don't let the little white arrows fool you, it isn't headed into FL



That high over the Atlantic is a bull... no wonder everything is creeping west.
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Quoting WindynEYW:
i just read the new york times online and couldn't find any mention of irene until i clicked on their weather tab & found a little sentence for sunday"hurricane Irene will be affecting area". way to go to give a heads up!!!



No Scandal, murder or sex... the bigger story will by Irenes impact on the Yankess or Giants schedule.. until its knocking on the door...
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Quoting MahFL:


So...how does one interpret those steering maps ?


First step is to imagine that's a snapshot, sort of like standing beside a highway and taking a picture of traffic. Everything on it is moving in real time and it takes other charts to know what's really happening. A little complicated.
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Back Later to check in...
"Irene be good while im gone, I don't want you a Category 4 around here..." "And Jose, Be good and follow what the NHC orders you to do, okay?" Be back later...
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Any thought about a hurricane watch being expanded to include the mid-Atlantic states at the 11?

I called my mom in Cape May. She says that some of her neighbors are starting to make their preparations. That's good...
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not a nice forecast to wake up to here in tidewater. someone could make a killing with a truck full of generators.
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Quoting nash28:


Her westward component is becoming less and less. Having said that, I still believe she could make it as far W as the NC/SC border. Right at the tip.


Definitely a possibility specially if her jogs are more W than N.
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Quoting wxobsvps:
Current steering. Don't let the little white arrows fool you, it isn't headed into FL



True. But might bring it a little closer to those of us on the central Florida coast.
Member Since: July 17, 2006 Posts: 0 Comments: 408
Quoting butterflymcb:


I also want to know the answer to that question...

What is that???


It's the eye wall closing off, just a little bit smaller than was anticipated. Still rather large tho..
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Quoting padirescu:
Wow, here in West Palm Beach (26 miles inland) I was just sitting here waiting for the first of the outer bands to get here and out of nowhere the Sun just peeked through the clouds following a couple of light showers. Wasn't expecting to see that at all today.


will probably be hit and miss around the area today.

7M back in Boca Raton, have already had about three good solid rains since 6A.
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anyone have a link to see future waves coming off of Africa?

I know this is a good thing but for goodness sakes!!.... it is approaching September and only 1 yellow circle on the map!
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Quoting K8eCane:


Well im in a tricky situation...the HURRICANE watch starts about 25-30 miles to my north...(Im in Wilmington) and now you guys are saying NC/SC border ?


Well crap! And I still think Grandpa should leave Atlantic Beach.

Thanks guys for answering my question earlier. Surf City is pretty close so I'm betting that Hurricane Watch will expand.


Local weather guy told me on facebook that if it shifts even 50 miles west that our conditions in Wilmington would be much worse.
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A lot of good friends in Little Harbour getting worked this morning.

North end of Eleuthra.

115-120 Sure beats a 135-150 mph storm that was forecast.

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I doubt a NC/SC direct hit. It is trending more west, but were talking just a few miles.

Maybe a Cape Lookout/ Morehead City Landfall vs. a Hatteras hit.

Im not sure the storm makes it far enough west to hit 78-79 W
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456. MahFL
Quoting wxobsvps:
Current steering. Don't let the little white arrows fool you, it isn't headed into FL



So...how does one interpret those steering maps ?
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So TD Ten is here, and will likely become Jose, Another TS... Irene's ACE now to 11.1, Total at: 24.3
Death toll has also climbed to 37 for this season now. 25 deaths; Arlene, 5 Deaths; Emily, 3 Deaths; Harvey, 4 Deaths; Irene. Sadly Irene could bring it up some more... =/
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Quoting Skyepony:
What is that on the SSE side there at the end of MIMIC?


I also want to know the answer to that question...

What is that???
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453. HCW
I wouldn't count on TD#10 being a fish as models do not have a clue on what it's doing and all you would need to do would be to look at what direction it has moved in the last 24 hrs
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Quoting K8eCane:


Well im in a tricky situation...the HURRICANE watch starts about 25-30 miles to my north...(Im in Wilmington) and now you guys are saying NC/SC border ?

I would prepare and anticipate hurricane force winds at this point.
Member Since: August 17, 2010 Posts: 21 Comments: 6939
Quoting FLdewey:
My trash cans are skeerd.

If not now, they will be shortly...
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Quoting Neapolitan:
ATCF 1200z for Irene:

AL, 09, 2011082512, , BEST, 0, 254N, 766W, 100, 950, HU, 64, NEQ, 60, 60, 25, 50, 1008, 300, 30, 0,


Pressure still sinking a little
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Quoting K8eCane:


Well im in a tricky situation...the HURRICANE watch starts about 25-30 miles to my north...(Im in Wilmington) and now you guys are saying NC/SC border ?


I live in Wilmington too and it is tough... I am going to get a few light supplies and some food just to be safe. If the track shifts west like some people predict will have to go out for more... however, i feel like the NHC knows what theyre doing and wouldve put us under a hurricane watch if needed. The fact that they didnt makes me feel confident that THEY are confident it will not make it this far westward.
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i just read the new york times online and couldn't find any mention of irene until i clicked on their weather tab & found a little sentence for sunday"hurricane Irene will be affecting area". way to go to give a heads up!!!
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ATCF 1200z for Irene:

AL, 09, 2011082512, , BEST, 0, 254N, 766W, 100, 950, HU, 64, NEQ, 60, 60, 25, 50, 1008, 300, 30, 0,
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Good mid morning blog. We're getting close to finding out some things. Any more westward and the Northern NC coast and the Delmarva penisula gets a historic storm. Not to mention DC/Balt. That would help our Northern friends a bit and knock down the second strike. Either way, this is not a good story. I think we will be remembering Irene for a long time. Today is get things together day, tomorrow will be crazy.

Cat 5: You've been on this well for the last few days, still betting on the western landfall.
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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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