Hurricane Irene Approaches the Bahamas

By: Dr. Jeff Masters , 7:42 AM GMT on August 24, 2011

Share this Blog
11
+

As of 2AM EDT, Hurricane Irene was located at 21.3N, 72.6W, 400 miles southeast of Nassau. It was moving west-northwest at 9 mph with maximum sustained winds of 100 mph, making it a Category 2 storm on the Saffir-Simpson scale. Irene has a minimum central pressure of 966 mb. Hurricane warnings have been issued for all of the Bahamas and the Turks and Caicos Islands. Tropical storm warnings are in effect for Haiti from Le Mole St. Nicholas to the Dominican Republic border.

Satellite Views
Figure 1 shows that Irene has a large eye visible in infrared imagery, (26 miles across accoring to a report from the Hurricane Hunters at 130AM) with well-defined outflow cirrus bands. Tuesday evening, TRMM, NASA's tropical research satellite, flew directly overhead Irene, getting a radar scan of the storm using it's downward pointing radar, shown in Figure 2. It is immediately apparent that Irene has well-developed bands of rain showers, with strong storms present in the eyewall.


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


Figure 2 TRMM radar overpass of Irene at 713PM EDT, August 22, 2011. Image courtesy of the Naval Research Laboratory

Track Forecast

Irene is forecast to move to the northwest, passing over all of the Bahamas by Thursday evening, then curving to the north. 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. After Saturday, Irene may pose a threat to Long Island and the New England coastline. However, NHC is quick to remind us that the average forecast error for day 4 is 200 miles, so don't stop your hurricane preparations if you aren't in the immediate area of landfall. 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 major hurricane (winds faster than 110 mph), within 24 hours.


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

Forecast models and adaptive observations
The different forecast models are in fairly good agreement about Irene's track through the Bahamas and along the east coast of the US. The GFDL, a dynamical hurricane forecasting model, which had been a western outlier from the other models is now agreeing with them. When a set of weather models using slighly different initial views of the atmosphere and slightly different ways of simulating how the atmosphere works all agree on a forecast, then meteorlogists tend to believe that the forecast is more likely to occur. The 00Z GFS and ECMWF (wind swath shown in Figure 4) forecasts are nearly identical, which furthur boosts forecaster confidence.

In the 11PM forecast discussion, the NHC forecaster praises the NOAA Gulfstream IV (aka Gonzo) for providing infomation about the atmosphere around Irene that will influence it's track. 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, and two flights for NOAA 42, a WP-3D (aka Kermit).


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

Impacts

In the immediate future, Irene will have a significant impact on the Bahamas and surrounding islands. Hurricane force winds are ongoing over the Turks and Caicos islands and southeastern Bahamas. These locations can expect storm surges that are 5-8 feet above tide levels. The northwestern Bahamas can expect hurricane force winds Thursday, and storm surges that are 7-11 feet above tide levels. The Turks and Caicos islands and all of the Bahamas can expect 6-12 inches of rain over the next two days.

I still think people living along the east coast of the US should closely monitor Irene and review their hurricane preparations. Irene will be a large storm, impacting areas far from the storm center track.

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: 478 - 428

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29Blog Index

I was given a warning yesterday when I mentioned negative comments about the commander in Chief, my bad, If I want to continue to post in here, it better be positive comments only!

Suns up this morning, feet hit the ground, all is good!
Member Since: Posts: Comments:
Good morning

Irene really got it together overnight as we were discussuing last night. CAT 3 no surprise with the pressure falls we were seeing.

Any word from TCI bloggers like CRS ??
Member Since: Posts: Comments:
ANYBODY THINK THE EYE'S GONNA GET BIGGER?
Member Since: August 18, 2011 Posts: 0 Comments: 994
Quoting trunkmonkey:
what's going on?
The Drudge Report is stating Irene is a Cat3!
the 5EST say it's a weak CAT2, when did things change, am I asleep at the wheel again?


8AM:

Link
Member Since: Posts: Comments:
Quoting stormwatcherCI:
Good morning. I know all eyes are on Irene but did anyone happen to notice that 90L is up to 50% chance for development ?
Stormwatcher-I asked this before & got lambasted by someone as a troll. Best to stick to Irene discussion...
Member Since: Posts: Comments:
Member Since: Posts: Comments:
ExumaMet keep us updated if u are able. Had my honeymoon on a houseboat there 10years ago..special place. Are there any boats seeking shelter there from the storm?
Member Since: Posts: Comments:
Quoting Waltanater:
Today marks the 19th Anniversary of Hurricane Andrew striking SFL! Do any of you (older) folk remember back then? I bet some of you on here were too young.


And Sunday is the 19th Anniversary of Super Typhoon Omar smacking Guam.
Member Since: Posts: Comments:
Quoting GeoffreyWPB:
90L...



90L POSS T.C.F.A.
Member Since: Posts: Comments:
GEOS IR "most recent animation frame"

I think that this will refresh periodically, but now this is the 8:25am image:

Member Since: Posts: Comments:
Quoting FLdewey:


Almost everyone here has a desk that leans to the left.

Odd.


I was sure Tampa would be back in the cone this morning when I woke up. Hope the NHC isn't screwing this one up. They should monitor the blog more so they can get expert opinion from high school kids.
Member Since: Posts: Comments:
You can see that second wind max rotating around the eye. Wonder if an EWRC is underway.

Member Since: August 19, 2005 Posts: 5 Comments: 5045
Quoting KrazyKaneLove:
Been lurking. I have to admit i am getting a little anxious here in WPB. We now have a tropical storm warning in effect but otherwise nothing. Just seems too close to call.


Lets not stir the pot with false information - the coastal waters along the east coast of Florida are under a Tropical Storm Warning, this is done as a precaution for boaters. There will be a lot of very rough surf up and down the east coast this week.

Link
Member Since: Posts: Comments:
Quoting Waltanater:
Today marks the 19th Anniversary of Hurricane Andrew striking SFL! Do any of you (older) folk remember back then? I bet some of you on here were too young.


5 years old, east side of the town of Kendall. Got ripped by the brunt of the northern eyewall and half the house was on the other end of the street by daybreak.
Member Since: Posts: Comments:
Long time lurker since 2006 from Virginia Beach checking in. Nobody here seems to be to concerned with Irene. Generally, these storms that come up the coast, stay far enough to the east that we do do not experience anything but a little rain. What do you guys think lies in my future for Saturday in terms of hurricane affects?
Member Since: Posts: Comments:
Quoting NasBahMan:


Hope everyone has completed their preparations in Exuma, still a lot to be done here in Nassau.
I hope you got all ur stuff done, too! LOL

Don't forget to post any updates info etc you get in my blog.
Member Since: Posts: Comments:
what's going on?
The Drudge Report is stating Irene is a Cat3!
the 5EST say it's a weak CAT2, when did things change, am I asleep at the wheel again?
Member Since: Posts: Comments:
Quoting Chucktown:
Its doing fine on track, click on Tropical Points, especially now that we have half a visible - looks like its gaining more latitude and not as much west longitude - great news !!

Link


does appear it will be a hair north of the next TFP. Very surprising since, according to the blog, it was wobbling west for most of the day yesterday.
Member Since: Posts: Comments:
Quoting Waltanater:
Today marks the 19th Anniversary of Hurricane Andrew striking SFL! Do any of you (older) folk remember back then? I bet some of you on here were too young.



I rode it out when it made it's often forgotten second landfall in Louisiana. One of the scariest nights of my life.
Member Since: Posts: Comments:
Trough is deepening to pick up Irene and expect a Northerly pull potentially by the 11 AM advisory. Forecast cone remains a little off (slightly west) but not much.
Member Since: Posts: Comments:
Quoting KrazyKaneLove:
Been lurking. I have to admit i am getting a little anxious here in WPB. We now have a tropical storm warning in effect but otherwise nothing. Just seems too close to call.



Only offshore, it doesn't include land areas.
Member Since: August 19, 2005 Posts: 5 Comments: 5045
Quoting NASA101:
That's a one BAD track for DC, NJ, NY, Mass - 06Z GFDL.. holy cow...




Wow. That would be a $100 billion mess, for sure.
Member Since: November 8, 2009 Posts: 4 Comments: 13473
90L...

Member Since: Posts: Comments:
UKMET (BLUE) would bring TS conditions to the coast.

Member Since: August 19, 2005 Posts: 5 Comments: 5045
Today marks the 19th Anniversary of Hurricane Andrew striking SFL! Do any of you (older) folk remember back then? I bet some of you on here were too young.
Member Since: Posts: Comments:
Been lurking. I have to admit i am getting a little anxious here in WPB. We now have a tropical storm warning in effect but otherwise nothing. Just seems too close to call.
Member Since: Posts: Comments:
I know the focus is on Irene and it should be, but in around 10-14 days I would be on the look out for some potential Gulf Of Mexico development. GFS is showing hints of something wanting to develop and move towards the west coast of Florida. Just another sign that we are indeed in the peak of hurricane season
Member Since: Posts: Comments:
Its doing fine on track, click on Tropical Points, especially now that we have half a visible - looks like its gaining more latitude and not as much west longitude - great news !!

Link
Member Since: Posts: Comments:
Position on infrared (GEOS East) as of 11:45Z:

Member Since: Posts: Comments:
That's a one BAD track for DC, NJ, NY, Mass - 06Z GFDL.. holy cow...



Member Since: Posts: Comments:
Quoting FLdewey:
Open ocean forecasts now calling for 40 foot seas well east of Florida as Hurricane Irene exits the Bahamas.

Need more wax.



I think you need a bigger board too.
Member Since: August 19, 2005 Posts: 5 Comments: 5045
I think we'll make Cat 4 by this afternoon. When that hit's the airwaves, the panic will start in ernest.
If anyone vacationing on the outerbanks of N.C., now is the time to get out. Even if Irene makes a "brush buy". A wobble so much as 50 miles west WILL make a hugh difference. I experienced the panic of Rita in Houston in 2005. NOT VERY PRETTY!
Member Since: Posts: Comments:
Irene so far...
Member Since: Posts: Comments:
436. GoWVU
Quoting wxobsvps:


I guess it is supposed to but the 594dm ht from Bermuda for the 00Z is kind of high for a weakening western flank of the atl high. We'll see. The 300 heading is a good sign, more latitude the better.


Thanks for the reply
Member Since: Posts: Comments:
435. Jax82
Quoting FLdewey:


Hahahaha.... oh please let it wash Trenton away.

I see we have a red circle... woop woop.


It's T-shirt time!!!!!!
Member Since: September 2, 2008 Posts: 1 Comments: 1261
Max number of images RSO loop in ir, gives better sense of the direction.
Member Since: September 23, 2005 Posts: 14 Comments: 10933


Quoting ExumaMET:
Just reporting from Exuma, Bahamas... we're getting squally conditions and have had a few wind gusts approaching 40kt.

I'm not liking the amount of wobbling to the west.
Good to see you in the blog, ExumaMet.... please feel free to post any updates you have in my blog as well as in the main blog.

Ya'll stay safe down there! And none of that wobbling... I would love to see this just exit to the east right now....

Member Since: Posts: Comments:
Anybody think the eye will get bigger?
Member Since: August 18, 2011 Posts: 0 Comments: 994
Watching for wobbles today in Jupiter, below resides 20-30 miles off the coast, Marine Tropical Storm Warning issued.

Sebastian Inlet to Jupiter Inlet.

Tonight: Tropical storm conditions possible. ENE wind 20 to 25 kt, with gusts as high as 30 kt. Scattered showers and thunderstorms, mainly after 11pm. Seas 5 to 7 ft.

Thursday: Tropical storm conditions expected. NE wind 31 to 36 kt, with gusts as high as 45 kt. Showers likely and possibly a thunderstorm. Seas 10 ft building to 13 ft.

Thursday Night: Tropical storm conditions expected. NNW wind 32 to 37 kt, with gusts as high as 45 kt. Showers likely and possibly a thunderstorm. Seas 17 to 18 ft.
Member Since: August 19, 2005 Posts: 5 Comments: 5045
Member Since: Posts: Comments:

Viewing: 478 - 428

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29Blog 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.