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

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

Share this Blog
17
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 796 - 746

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22Blog Index

Thanks Tampa. If the center of Irene really does shift west towards Morehead City... Wilmington will be very close not only to the hurricane force winds, but major hurricane force winds. Thats what scares me about the current scenario... still being under a TS watch. Hopefully it doesnt shift west because no one here is prepared at all for a major hurricane
Member Since: August 4, 2011 Posts: 0 Comments: 631
Quoting libertygirl:
CNN reports 27 Navy ships moving out of port in Virginia - happening now. This should "speak" to all of you up in Mid Atlantic...

They do that whenever there is a big storm, including Nor'easters. Should do nothing to raise your alarm level.
Member Since: Posts: Comments:
Quoting surfsidesindy:


And up until 24hrs beforehand, the NHC said Andrew wasn't going to hit you..


I sympathize with everyone feeling this way, as I said last night, this was the utmost test of faith in the NHC.

I think that we have to recognize how much the forecasting has changed since Andrew. Even though there have been some issues, those forecasts usually say that there is a higher chance of uncertainty, where as this one did not.

It is absolutely true that 24 hrs prior to Andrew they did not believe it would hit South Florida. I believe what happened in that forecast was that they thought the high was going to back off, and it was going to turn out to sea. The high then "bridged" effectively cutting off the path. If you look at the track you will see that when it started west it never moved.
Member Since: Posts: Comments:
Later today i will put up a section just for Irene with as many Radar sites and can put up live to help as many as i can....so Sorry the many of Millions of what they are about to go thru. I have been there and its no fun at all to have no power for weeks and no water. You just don't understand until you have been there!
Member Since: Posts: Comments:
Quoting klaatuborada:
Hello friends. Klaatu from Cape Cod. Just checking in. Irene's track so far is eerily similar to Hurricane Bob which hit here in 1991. Has there been any comparisons? I wonder if I could get the coordinates that Bob took and superimpose them on what Irene is doing, but perhaps that is already available somewhere else? Anyone?

Let me know. In the meantime, already have water, batteries, and prayer book.


If it were me, I'd be getting the hell off the island. Keep this in mind: If I'm wrong, you can call me an idiot (and whatever words come to mind); if I'm right, you can say "Thank you!".

And if it was my family, I'd be packed and out already. If you wait too late, the roads will be packed and you'll ride the storm out in your car...if it doesn't flood and wash you away. I live in Florida and my back up plans involve high ground 150 miles away in Georgia...
Member Since: Posts: Comments:
Quoting 12george1:

It's 10 a.m.


The crow flies at midnight.
Member Since: Posts: Comments:
Oh wow, I think you really can invest in the company that makes the dropsondes.
Member Since: August 22, 2006 Posts: 0 Comments: 1451
Quoting Dem86Mets:
I know this is a non event for South Florida but I just had a 41 MPH gust here at my home in Deerfield Beach.


Stuart believes you! It is not JUST the gusts--it is the fact that we could be having them ALL day.
Member Since: Posts: Comments:
787. Vero1
Quoting ncstorm:


Can you provide a map of that?

http://www.stormpulse.com/hurricane-irene-2011 Click on the "model button"
Member Since: Posts: Comments:
Quoting Speeky:
Has anyone here been through a cat 2 hurricane? I live in New York City and I am a little afraid of the possiblity hurricane Cat 1+ hitting here.


Yes, direct hit by Ike but the two are not comparable. Big difference between a straight on GOM hit and a skirting the east coast hit, I would think.

Perhaps somoeone with more knowledge could elaborate on that.
Member Since: Posts: Comments:
Quoting wxobsvps:
NRTI ..

If you have that link to the 6hr sounding data that would be great. I lost it. Hopefully you are lurking.


atmoaggie posted a better one

Map


Webpage
Member Since: September 23, 2005 Posts: 14 Comments: 10875
Quoting FLWxChaser:
With daytime heating these band should get going a little further North in a few hours. Live streaming in the Cocoa Beach area most likely near lunch time.

No sustained TS winds, which is what they would require for warnings.

It's 10 a.m.
Member Since: Posts: Comments:
I know this is a non event for South Florida but I just had a 41 MPH gust here at my home in Deerfield Beach.
Member Since: Posts: Comments:
If we waited for them to tell us what to do/expect....:-P....they have not once, (in 25yr memory) issued warnings WELL BEFORE the weather event. By all means - if you are on the Mid Atlantic/New England Coast - EVAC BEFORE they issue EVAC order!
Quoting 69Viking:
Honestly why aren't Tropical Storm warnings out for the Florida coastline??? The advisory states Tropical Storm Force winds extend 255 miles from the center and Irene is passing at less than 200 miles from the Florida coast. It's also possible they could see tornadoes from Irene and coastal flooding. Very strange.
Member Since: Posts: Comments:
Quoting Vero1:
WOW... the TVCN is west of Morehead City, NC and west of Trenton, NJ


Can you provide a map of that?
Member Since: Posts: Comments:
Quoting CarolinaHurricanes87:


Tampa... do u have that same wind speed projections chart that u posted for the NE.. for the SE?


YES.

Member Since: Posts: Comments:
Quoting SFlwxwatcher:

Mostly a lurker from So Fl, also an Andrew survivor. I'm not sure that you've ever been through a Cat 5 storm, but when we living here in Miami see a huge storm sitting just off our shore, it's a bit disconcerting to say the least. I trust and believe the NHC track, otherwise my shutters would be closed and I would have stocked up on supplies, but please don't discount the slight feeling of uneasiness any of us living here have when we see the satellite images.


And up until 24hrs beforehand, the NHC said Andrew wasn't going to hit you..
Member Since: Posts: Comments:
Quoting TampaSpin:
Seen the Models moving WEst late last nite......but they moved what looks like almost 100miles West on average.....WOW!


A bunch of chasers who canceled on the OBX are kicking themselves today.
Member Since: Posts: Comments:
Quoting TampaSpin:
Seen the Models moving WEst late last nite......but they moved what looks like almost 100miles West on average.....WOW!


Let the models move 100NM west. As long as Irene doesn't pull that stunt....
Member Since: Posts: Comments:
Quoting Speeky:
Has anyone here been through a cat 2 hurricane? I live in New York City and I am a little afraid of the possiblity hurricane Cat 1+ hitting here.


Yes you should be scared. But face fear with action. Either procure gas now to get out of the way (gas WILL run out). Or get ready for a hell ride - Go stock up on water and non perishable food now. Anything you could possibly need this next week, you need to procure. Because stores can't run credit/debit machines without electricity. Do you smoke? Stock up. Have feminine needs impending? Stock up. Get yourself a nice bottle of liquor while you're at it. You'll want a drink - trust me. Also, pull several hundred in cash out of the ATM before it approaches, too. Cash is king.
Member Since: Posts: Comments:
Great, currently getting more MONSOON rains for the Mid Atlantic. Some locations are at 200%+ rain fall over the last 2 weeks in the area where Irene is target to move through on Sunday.

Also this front over the NE is moving through faster than expected. I can see why the models have shifted WEST.
Member Since: Posts: Comments:
How is there no TS Watch/Warning for SEFL?

These squalls can produce waterspouts and even a possible tornado!

Member Since: Posts: Comments:
Quoting TampaSpin:


Tampa... do u have that same wind speed projections chart that u posted for the NE.. for the SE?
Member Since: August 4, 2011 Posts: 0 Comments: 631
771. MahFL
Quoting surfsidesindy:


I don't get it either. In East Central FL there is a TS warning for the WATERS but not the land.

.WATCHES/WARNINGS...
FOR MARINE INTERESTS...A TROPICAL STORM WARNING IS IN EFFECT FOR
ALL PORTIONS OF EAST CENTRAL FLORIDA ATLANTIC WATERS.

Last time I checked my beach is next to my water here in Cape Canaveral.


surfsideindy,....do...not...ever...buy...a...boat ...
Member Since: Posts: Comments:
With daytime heating these band should get going a little further North in a few hours. Live streaming in the Cocoa Beach area most likely near lunch time.

No sustained TS winds for Florida, which is what they would require for warnings.
Member Since: Posts: Comments:
At my office here in Deerfield Beach, it is raining. However there is absolutely no wind associated with the rain...it is coming straight down. I kinda expected today to be hit and miss rain, but breezy. One thing for sure...I won't have to deal with that nightmarish sunburn I got when TS Bonnie made landfall!
Member Since: Posts: Comments:
GFDL thinks it could be pretty windy inland


Member Since: Posts: Comments:
Seen the Models moving WEst late last nite......but they moved what looks like almost 100miles West on average.....WOW!
Member Since: Posts: Comments:
Quoting 69Viking:
Honestly why aren't Tropical Storm warnings out for the Florida coastline??? The advisory states Tropical Storm Force winds extend 255 miles from the center and Irene is passing at less than 200 miles from the Florida coast. It's also possible they could see tornadoes from Irene and coastal flooding. Very strange.


+10 I agree we should all be smart enough to figure out how to prepare with or without the NHC but it's not ME I"m worried about, it's all my *&%$ neighbors who don't put their stuff away and it blows into MY house.
Member Since: Posts: Comments:
Quoting cat5hurricane:

More likely only a temporary stall as she is beginning to feel the weakness to her north and trying to get her footing down as she rounds the western periphery of the ATL ridge.

In addition, a temporary slowdown and/or wobble movement is sometimes indicative of a storm undergoing an EWRC, which Irene appear to be in the process of doing.

This is such an impressive system,...but not fun when you in it's path!

Irene pounds Bahamas, N. Carolina on hurricane watch
* Reports of homes washed away on one south Bahamas island

* US East Coast on alert at approach of powerful hurricane

* U.S. Navy ships ordered to leave port to ride out storm

* Warning of risk to New England, Long Island from Sunday



Irene pounds Bahamas, spins north toward watchful US
Storm damages dozens of homes on island chain; East Coast checks bridges, readies plans
Member Since: Posts: Comments:
764. gdbob
Trying to get home to Norfolk this weekend. When do you think the airports will start shutting down? Looks like maybe Richmond or Durham will be the closest that may stay open.
Member Since: Posts: Comments:
Thanks for the replies MrstormX and kwgirl - will keep watching and listening just in case things change :)
Member Since: Posts: Comments:
Quoting 69Viking:
Honestly why aren't Tropical Storm warnings out for the Florida coastline??? The advisory states Tropical Storm Force winds extend 255 miles from the center and Irene is passing at less than 200 miles from the Florida coast. It's also possible they could see tornadoes from Irene and coastal flooding. Very strange.

this is why. the 225 miles you speak of is to the NE.

here are the forecast 34 knot winds at 2PM today.

34 KT...220NE 180SE 100SW 130NW.
Member Since: August 6, 2007 Posts: 0 Comments: 693
----
Member Since: Posts: Comments:
Quoting Speeky:
Has anyone here been through a cat 2 hurricane? I live in New York City and I am a little afraid of the possiblity hurricane Cat 1+ hitting here.


I went through Ike in Texas as a low end cat1... And we were over 100 miles inland. Many trees down and power was out for quite a while. If you're a good distance from the water, just make sure anything that can blow away is put up. Also get enough food for a few days that can be eaten if you don't have power. Don't expect anywhere around you to have power either. Gas up the car now (just like everybody else will be doing).
Member Since: Posts: Comments:
Quoting P451:


Yup. Clearly on an Andrew path through the Bahamas right now. Going to cross Miami and head right for NOLA.\



I have no idea what the models are doing and the NHC as usual is absolutely clueless. This is going to be serious.

/sarcasm.


Mostly a lurker from So Fl, also an Andrew survivor. I'm not sure that you've ever been through a Cat 5 storm, but when we living here in Miami see a huge storm sitting just off our shore, it's a bit disconcerting to say the least. I trust and believe the NHC track, otherwise my shutters would be closed and I would have stocked up on supplies, but please don't discount the slight feeling of uneasiness any of us living here have when we see the satellite images.
Member Since: Posts: Comments:
758. Jax82
Member Since: Posts: Comments:
Quoting pottery:
Meantime....

Trinidad weather now..
Temp 79F
Humid 89%
Wind WNW
Pressure 1016
Rain.

Sky is black and a constant drizzle since about 5:00 am.
Good weather, if you're a duck.


quack much lately?
Member Since: Posts: Comments:
756. Vero1
WOW... the TVCN is west of Morehead City, NC and west of Trenton, NJ
Member Since: Posts: Comments:

Quoting starbuck02:
Jacksonville is getting pounded...ahhhh....oooops nope sorry, just a little cloudy at the moment :)
sounds like a 'Cloud Event!'
Member Since: Posts: Comments:
Quoting ncstorm:


which model is pointing at Jacksonville?



GFDL, I think
Member Since: August 4, 2011 Posts: 0 Comments: 631
Quoting ncstorm:


which model is pointing at Jacksonville?


Jacksonville, NC
Member Since: Posts: Comments:
750. MahFL
Quoting TruthCommish:


I've been through a CAT 4 Andrew and CAT 3 Wilma. Lets just say they were not fun. Living without electricity for 2 weeks SUCKS!


Andrew was updgraded to a Cat5.
Member Since: Posts: Comments:
Quoting islander101010:
fire ants are going crazy now
I was wondering about the ants...
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting 69Viking:
Honestly why aren't Tropical Storm warnings out for the Florida coastline??? The advisory states Tropical Storm Force winds extend 255 miles from the center and Irene is passing at less than 200 miles from the Florida coast. It's also possible they could see tornadoes from Irene and coastal flooding. Very strange.


They were issued for coastal waters.
Member Since: Posts: Comments:

Viewing: 796 - 746

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.