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: 1228 - 1178

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




Member Since: Posts: Comments:
Looking at the recent track are they calling for the storm to stall for a couple hours in the Bahamas ?

It does not look like it is stalling on the sat, or is it just me
Member Since: Posts: Comments:
Basically watch to see what happens at 77W
Member Since: Posts: Comments:
Quoting Buhdog:


wilma did not bounce last minute. Charley was only slightly bounced...but the angle of the costline made it more severe. The NHC is nailing this 3 days in right now, follow that map.


I remember the track for Wilma was supposed to track west of Lake Okeechobee, but the eye came right over my house in Boca.
Member Since: Posts: Comments:
Quoting 69Viking:


Show proof of that? Irene was supposed to go South of Puerto Rico and cross Hispanolia and in less then 24 hours it had gone North of Puerto Rico. Nothing in Forecasting is 90% guaranteed anyone with any clue about weather would know that.

I'm no a weather expert at all and don't want to upset anybody with my opinion about the Hurricane track,this is just one of my hobby's following tropical systems,and this blog is very good!!,but let's wait 24-36 hours and see if my comments are correct or wrong,if wrong I will be the first to recognized.
Member Since: Posts: Comments:
1221. air360
Although i totally agree with people who say wobbles are not to be given much credit...but viewing this starting at 1315 to the end of the loop does show over an hour of more W motion....which puts it on track to actually miss the next forecast point to the west. just sayin...

Link
Member Since: Posts: Comments:
Over the last 3 advisories Irene has moved .8N and 1.5W, where I went to school that tells me Irene's motion has been and still is WNW.
Member Since: Posts: Comments:
For every wobble west, there is a wobble NNW.
Member Since: Posts: Comments:
NEW STEERING MAP:

Member Since: Posts: Comments:
Quoting E46Pilot:



People still use IE, thats the problem. Use Mozilla Firefox, it is much better, and no problems.

And the FlashBlock addon makes this and other sites much easier to read.
Member Since: Posts: Comments:
1215. KEEPEROFTHEGATE (Mod)
09L/MH/I/C3
RI FLAG (FLAG)
MARK
24.00n/74.00w forecast point





ALWAYS FOLLOW NHC/TPC FORECASTS FOR ALL WARNINGS REGARDING THIS STORM
Member Since: Posts: Comments:
1214. Gorty
Who think we will have Jose before September?
Member Since: Posts: Comments:
If she is going NW by the time she gets to 77W, it's check mate for the CONUS
Member Since: Posts: Comments:
1210. ph34683
Quoting overwash12:
They have well built houses down there,N.C. is pretty strict on their building codes.


Yes, that is true. I'm glad for that! He's about 200 yards from the water though so that scares me.
Member Since: Posts: Comments:
Click "ignore user" to get rid of Jason(not so)coolman2004......it'll also put him on your BLOCK list. Admin will deal with THAT IDIOT!!!
Member Since: Posts: Comments:
1208. air360
**anxiously awaiting 12GFS**

:)
Member Since: Posts: Comments:
1207. Buhdog
Quoting E46Pilot:


I do agree with you, but a slight unseen bounce can mean a world of difference. Remember Wilma, and Charley? The both bounced at the last minute.


wilma did not bounce last minute. Charley was only slightly bounced...but the angle of the costline made it more severe. The NHC is nailing this 3 days in right now, follow that map.
Member Since: Posts: Comments:
Quoting portcharlotte:
The west wobble as seen on the NASA site is now about 1.5 hours worth..it should get some attention


Yes it should, could mean a big difference on landfall location
Member Since: Posts: Comments:
Quoting reedzone:
I have friends and family on Long Island who are not taking this storm seriously, brushing it off like it's another Earl. If you live on LI, this is historic, we have never seen a storm like this since Hurricane Gloria in 1991. Please, don't shove this one by and start making ur evacuation plans, Long Island is at sea level and when you have a storm that was a Category 4, the surge can be catastrophic. PLEASE, head my advice and prepare for Irene. This isn't an Earl where it recurves at the last minute, the highs are set in place and the weakness will lead it right up the coastline. A category 2 Hurricane is set for landfall as of the 11 a.m. track.


Are you right in line with the NHC forcast? Or do you this still possible swaying furthur east or west with time? I have noticed that the trough over the midwest is a bit weaker than forcasted. I don't know what implications if any this would have?
Member Since: Posts: Comments:
1202. Lykkan
Seems like the wobble to the west continues. Cuban radar showing the eye nicely.
Member Since: Posts: Comments:
Quoting reedzone:
I have friends and family on Long Island who are not taking this storm seriously, brushing it off like it's another Earl. If you live on LI, this is historic, we have never seen a storm like this since Hurricane Gloria in 1991. Please, don't shove this one by and start making ur evacuation plans, Long Island is at sea level and when you have a storm that was a Category 4, the surge can be catastrophic. PLEASE, head my advice and prepare for Irene. This isn't an Earl where it recurves at the last minute, the highs are set in place and the weakness will lead it right up the coastline. A category 2 Hurricane is set for landfall as of the 11 a.m. track.


CORRECTION: Gloria was in 1985, not 1991.. Getting mixed up with Bob and Gloria. Meant to say Gloria in 1985.
Member Since: Posts: Comments:
If she is going NW at 77W, it's check mate for CONUS
Member Since: Posts: Comments:
1198. KEEPEROFTHEGATE (Mod)
Quoting hurricanejunky:


I don't think Irene will be reaching forward speeds of 60 mph as the 1938 storm did though...
maybe 70 mph instead fast mover less damage low surge
Member Since: Posts: Comments:
Guys is the reason its moving WNW is because its wobbling. I still think this will move to NW.
Member Since: November 1, 2003 Posts: 4 Comments: 234
Quoting hurricanejunky:


The wobbling continues....


Wobble west, wobble north equaly nw movement
Member Since: Posts: Comments:
Quoting ph34683:


Yes, he lives there year-round.
They have well built houses down there,N.C. is pretty strict on their building codes.
Member Since: Posts: Comments:
The west wobble as seen on the NASA site is now about 1.5 hours worth..it should get some attention
Member Since: Posts: Comments:
Quoting Hurricane1956:

With all your respect,I believe the eye of the Hurricane is following the Hurricane Center points exactly as they lay it out.I'm very confident here in Miami about the Hurricane Center confidence in their track otherwise they could easily issued Warnings this morning or yesterday,this is my own opinion after being a member of this blog for many years,the Hurricane center track in the 2-3 days range is 90% accurate.


Show proof of that? Irene was supposed to go South of Puerto Rico and cross Hispanolia and in less then 24 hours it had gone North of Puerto Rico. Nothing in Forecasting is 90% guaranteed anyone with any clue about weather would know that.
Member Since: Posts: Comments:
Quoting Smikey:
O

ok now he is posting porn, I've got to call it quits on looking at the forum now until that is corrected, since my ignore is not working, and I'm at work.

I hope you all you can correct this so I can come back.



If the ignore button doesn't work, go to your blog, Blog Control Panel on the right, then click on 'edit ignored list', there you can enter the user handle you wish to ignore.

Concerning Irene, I have watched the gradual eastward shift of the cone over the last couple of days - may it continue like this. I hope the trough is strong enough to have some effect on Irene.
Member Since: Posts: Comments:
1190. wpb
anyone have the link for noaa satellite quick scan
Member Since: Posts: Comments:
Quoting ecflweatherfan:
Um, here is a way to get the blog administrator's attention... EVERYBODY and I mean EVERYBODY, hit the ! button next to Jason's posts. I have already done that myself. If you love the quality information that you get from this blog, please do us all a favor. I look to this blog for insight into models and steering and all other sorts of information (and even humor from time to time), but to have bandwidth tied up with useless information that people, like Jason post, is a severe injustice to all of us that want to learn and share thoughts.


That is not Jason, say what you will about him but his posts were at least all weather related, he never posted vulgar pictures like this impostor who is evidently succeeding in making Jason look bad.
Member Since: Posts: Comments:
Just paid for full membership $10...Having 40 frames of NEXRAD Radar...priceless $$ :)..

Anyone else noticed the trough plowing through the Northeast is forcasted to be slightly weaker? I'm just taking that from the Severe weather outlook, which has shifted the protential severe zone much further to the northeast of prevouis position. Did't know if this would play any part?





Member Since: Posts: Comments:
Where is Levi's update?
Member Since: Posts: Comments:
1186. ph34683
Quoting overwash12:
They might only let locals on,does he own property on the OBX?


Yes, he lives there year-round.
Member Since: Posts: Comments:
With all your respect,I believe the eye of the Hurricane is following the Hurricane Center points exactly as they lay it out.I'm very confident here in Miami about the Hurricane Center confidence in their track otherwise they could easily issued Warnings this morning or yesterday,this is my own opinion after being a member of this blog for many years,the Hurricane center track in the 2-3 days range is 90% accurate.
Member Since: Posts: Comments:
Quoting Hurricane1956:

With all your respect,I believe the eye of the Hurricane is following the Hurricane Center points exactly as they lay it out.I'm very confident here in Miami about the Hurricane Center confidence in their track otherwise they could easily issued Warnings this morning or yesterday,this is my own opinion after being a member of this blog for many years,the Hurricane center track in the 2-3 days range is 90% accurate.


I do agree with you, but a slight unseen bounce can mean a world of difference. Remember Wilma, and Charley? The both bounced at the last minute.
Member Since: Posts: Comments:
Quoting overwash12:
Long Island express, the sequel!


I don't think Irene will be reaching forward speeds of 60 mph as the 1938 storm did though...
Member Since: Posts: Comments:
1182. 996tt
Quoting Smikey:
O

ok now he is posting porn, I've got to call it quits on looking at the forum now until that is corrected, since my ignore is not working, and I'm at work.

I hope you all you can correct this so I can come back.



Haha, the work thing is funny. Worried about some random picture, but okay for employer to pay you to participate in a blog.
Member Since: Posts: Comments:


Cat 2 storm in the NE, will bring a cat 4 surge just like Ike, because the wind field is BIG

Member Since: Posts: Comments:
Quoting ph34683:


My dad is and will be on OBX tomorrow through the storm (even though I told him not to!)

WB3CWK is his call sign/handle/ whatever you call it...
They might only let locals on,does he own property on the OBX?
Member Since: Posts: Comments:

Viewing: 1228 - 1178

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.

Local Weather

Mostly Cloudy
82 °F
Mostly Cloudy