Category 2 Irene Approaches The Bahamas

By: Dr. Jeff Masters , 7:51 AM GMT on August 23, 2011

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As of 2am EDT, Hurricane Irene was located at 20.1N, 69.7W, 135 miles southeast of Grand Turk Island. It was moving west-northwest at 12 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 978 mb. Hurricane warnings have been issued for the northern coast of the Dominican Republic from the Haiti board to Cabo Engano, the southeastern and central Bahamas, and the Turks and Caicos islands. Hurricane watches have been posted for the north coast of Haiti from Le Mole, St. Nicholas to the Dominican border and the northwestern Bahamas. Tropical storm warnings are in effect for all of Haiti and the southern coast of the Dominican Republic from Cabo Engano to Santo Domingo.

5AM Update
As of 5am EDT, Hurricane Irene was located at 20.3N, 70.1W, 105 miles southeast of Grand Turk Island. It was moving west-northwest at 12 mph with maximum sustained winds of 100 mph, keeping it a Category 2 storm on the Saffir-Simpson scale. Irene has a minimum central pressure of 978 mb.

Figure 1 shows that Irene is maturing into a vigorous storm, with apparent waves in the western edge of the cirrus outflow.


Figure 1 IR satellite view of Irene taken at 135AM EDT, August 22, 2011

Track Forecast

Irene is forecast to move to the north-northwest, passing over all of the Bahama islands by Thursday evening, at which points it starts curving to the north. Irene is forecast to make landfall in the US near Wilmington, NC Saturday evening. However, it is important to note that this is not a definitive forecast, the average forecast error for day 5 is 250 miles. The timing of Irene's recurvature depends on how quickly several small troughs of low pressure in the Northeastern US move to the east. After Saturday, Irene may pose a threat to the mid-Atlantic coastline and locations further north, but it is too early to make a skillful forecast for those regions.

NHC is forecasting for Irene to become a major hurricane (winds faster than 110 mph), within 24 hours, then reaching peak intensity at 130 mph (Category 4 storm) by 8pm EDT Thursday evening.

Forecast models and adaptive observations
The different forecast models are in rough agreement until Irene nears the Carolinas. The dynamical hurricane forecasting models, GFDL and HWRF, have Irene making landfall near Charleston, SC. NGFDL (a variant of the GFDL that uses NOGAPS for background conditions) has landfall near Morehead City, NC, and the GFS has Irene crossing the Outer Banks. The UKMET forecast track splits the difference, placing Irene near Myrtle Beach, SC at landfall.

To reduce the model spread, and improve the track forecast error, the NOAA Gulfstream IV and an Air Force WC-130J have been flying dropsonde missions north of Irene. A dropsonde is an meteorological instrument package dropped from a plane that can tell you the vertical profile of temperature, pressure, moisture, and winds. By flying these missions, the dropsondes can improve all of the numerical weather prediction models initial picture of the atmospheres, which improves the forecast. Also, NHC has asked NWS offices in the southeastern US that launch weather balloons to do so every 6 hours instead of the normal 12 hour frequency.


Figure 2 Official track forecast of Irene as of 2am.

5AM update
The 00Z ECMWF forecast is available and Figure 3 shows the maximum wind speed over the next week for the eastern coast of the US. Green indicates tropical storm force winds, while yellow and orange are hurricane-force winds. The important thing is not to fixate on the predicted landfall location, but to see that Irene's winds will affect areas far away from landfall. The GFS, not shown, agrees with ECMWF that Irene will have a large area of tropical-storm force winds associated with it.

Figure 3 Maximum wind-speed in mph from the 00Z August 23 ECMWF forecast for the next week.

Impacts

In the immediate future, Irene is expected to have a significant impact on the Bahamas and surrounding islands. Hurricane force winds are forecast to reach the southeastern Bahamas and the Turks and Caicos sometime this afternoon or evening. These locations can also expect 5-10 inches of rain. Three to six inches of rain are forecast over northern Hispaniola, with isolated areas receiving up to 10 inches. This could lead to flash flooding and mudslides in mountaineous terrain. NHC is predicting a storm surge of 9-13 feet above normal tide level for the southeastern Bahamas and the Turks and Caicos.

Outside of the islands immediately impacted by Irene, it is my judgement that everybody living on the eastern coast of the US should monitor Irene and review their hurricane preparations over the next few days.

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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My house is now directly under an "m" circle....

I hope this thing shifts further east! Im glad I took care of all my preperations yesterday. Looks like panic mode is setting in for ENC today.
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Irene could become a major right on top of the Bahamas.
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Hello 90L:

BEGIN
NHC_ATCF
invest_al902011.invest
FSTDA
R
U
040
010
0000
201108231157
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 90, 2011, DB, O, 2011082306, 9999999999, , , , , , METWATCH, , AL902011
AL, 90, 2011082306, , BEST, 0, 122N, 190W, 25, 0, DB, 0, , 0, 0, 0, 0,
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Quoting Chicklit:
Link to 8 AM NHC Forecast Discussion Irene



I wish BahaHurricane would check in.


he said last night he had a lot to do today..by the time it gets over New Providence, it will be a Cat 4..
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Irene will most likely be the size of Texas if she keeps expanding..
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Link to 8 AM NHC Forecast Discussion Irene



I wish BahaHurricane would check in.
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378. MahFL
So Irene has slowed down by 2 mph. Is that enough to significantly delay the coastal arrival ? It's a long way from Hispaniola to NC, via the Bahamas....
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Quoting earthlydragonfly:
Im not the one saying it...  Im just wondering why it is important to you!



I see it being used a lot lately and I am not sure what the purpose is. That's all..
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Quoting weatherguy03:
Looking like a Cat 3 moving into North Carolina then a Cat 2 to Cat 1 moving up the East Coast into New England. A large segment of the population will be affected by Irene along the East Coast.


You pretty confident in the forecast track at this point?
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Irene has passed the point on the DR coast where her motion matches the caostline... She's now starting to move away from land on a WNW heading. Land Interaction from now up until this point is going to be much, much less.

Stay safe those of you in the Bahamas.
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What are the chances of the models moving back south? I don't think I've ever noticed them doing that once they start to move north; what would make the storm trend more south than where it's currently forecasted to land?
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06Z GFDL..

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Quoting MahFL:
I think right now Irene is only drifting due West.


She's moving WNW 295 at 10mph. Not drifting or moving west. If you look at the satellite as well, you can confirm the movement to the WNW, granted it is slower than her movement yesterday. She is pretty much right on her forecast track at the moment. Maybe even moving slightly more north of her forecast track if you look at the visible satellite images.
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Quoting earthlydragonfly:
Im not the one saying it...  Im just wondering why it is important to you!



My apologies...
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06Z GFDL and HWRF on that site GFDL is labled GHM
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Is recon alright? I just went out for an hour and it hasn't updated.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Quoting Waltanater:
When is that 1st trough expected to affect Irene? Another question, does anyone think several troughs in succession are just as strong as a large trough? I mean will it do the job just the same in pulling it N or NE or do you think the fact of several troughs will cause the timing of this event of re-curvature to be delayed? Timing is the biggest issue here and it seems that Irene is on its own time schedule. I am not convinced of the forecaster's confidence so far.


1st trough has already come through and started to lift to the north of Irene. 2nd impulse is on it's way. There is some spread in the models cause they all handle differently how strong the following series of shortwaves will be...
Member Since: December 18, 2006 Posts: 7 Comments: 2685
This may very well mean nothing, but just a little observation:

Last year, our first Cape Verde hurricane was Danielle, and it was recurved well to the east of the US. As she was moving out, Earl began to develop, and he got much further west than Danielle managed.

Almost at exactly the same dates this year, we have Irene moving round, very close to, if not over the US. Now it's looking like we will have 90L about the same distance behind Irene as Earl was to Danielle, and models are hinting at development. It will be interesting to see if we have the same effect as last year, and if potential 90L gets further west.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
ON THE FORECAST TRACK...THE CORE OF IRENE WILL PASS TO THE NORTH OF THE DOMINICAN REPUBLIC AND HAITI THIS MORNING...NEAR OR OVER THE TURKS AND CAICOS ISLANDS AND THE SOUTHEASTERN BAHAMAS TONIGHT...AND BE NEAR THE CENTRAL BAHAMAS EARLY WEDNESDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 100 MPH...160 KM/H...WITH HIGHER GUSTS.

IRENE IS A CATEGORY TWO HURRICANE ON THE SAFFIR-SIMPSON HURRICANE WIND SCALE.

ADDITIONAL STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS...AND IRENE COULD BECOME A MAJOR HURRICANE LATER TODAY OR ON WEDNESDAY.

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Quoting ncstorm:


some of the models take it off the OBX but we will still see a hard impact even from that scenario with some of the models predicting a Cat 4..I honestly dont see any difference in the models that were aiming at us yesterday before the dropsondes and the models with the dropsondes added to them..the only thing that changed was the GFDL and UK who are aiming at Charleston..


When do you think we would get watches or warnings? Reason being, thats when people take notice and i would like to know what the schools are thinking. My son is spose to start Thursday. And I would also like to know which will be open for shelters and be able to plan for my animals so my son doesnt freak out if we have to go to a shelter. I dont live in a mobile home. However its just he and I and i dont feel brave enuf to do a high cat 3 or a cat 4 alone. I have done cat 1 and 2s but the cat3 i did was with a house full of others.
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Quoting presslord:
I have a disaster preparedness meeting today with a group I won't name...and I can promise ya: it's gonna be a hard sell to convince these folks that we aren't yet OK...


At least we've got one sensible head in there with them to make sure they understand the risk!
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Also, the general public does not have the attention span to watch a hurricane and keep posted on what is happening. They hear that the track shifted, and assume that is it. They don't realize it can shift back and forth.

When the storms take more than a day, or slow down, the people quickly lose interest. They also tend to believe what they can see, which is nice weather and sunny skies outside, not that a major storm is coming.

Quoting presslord:
I have a disaster preparedness meeting today with a group I won't name...and I can promise ya: it's gonna be a hard sell to convince these folks that we aren't yet OK...
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Has the eye shown up yet?
Member Since: August 18, 2011 Posts: 0 Comments: 994
I wonder what is going on in that eyewall...Guess we'll find out soon.

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Looks like the NAM is showing a slightly weaker trough...

Member Since: December 18, 2006 Posts: 7 Comments: 2685

Hurricane IRENE Public Advisory
BULLETIN
HURRICANE IRENE INTERMEDIATE ADVISORY NUMBER 12A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011
800 AM EDT TUE AUG 23 2011

...CORE OF IRENE HEADED TOWARD THE TURKS AND CAICOS ISLANDS AND THE SOUTHEASTERN BAHAMAS...


SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...20.6N 70.6W
ABOUT 70 MI...110 KM SSE OF GRAND TURK ISLAND
ABOUT 55 MI...90 KM N OF PUERTO PLATA DOMINICAN REPUBLIC
MAXIMUM SUSTAINED WINDS...100 MPH...160 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...978 MB...28.88 INCHES




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356. MahFL
I think right now Irene is only drifting due West.
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I have a disaster preparedness meeting today with a group I won't name...and I can promise ya: it's gonna be a hard sell to convince these folks that we aren't yet OK...
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Quoting scott39:
Would a short wave trough have that much impact, if the first trough doesnt do its job to weaken the H ? Im still learning , so that is why Im asking these questions during slow time.
When is that 1st trough expected to affect Irene? Another question, does anyone think several troughs in succession are just as strong as a large trough? I mean will it do the job just the same in pulling it N or NE or do you think the fact of several troughs will cause the timing of this event of re-curvature to be delayed? Timing is the biggest issue here and it seems that Irene is on its own time schedule. I am not convinced of the forecaster's confidence so far.
Member Since: May 16, 2010 Posts: 0 Comments: 1455
Quoting presslord:


yup...the problem is gonna be gettin' people here to kepp watchin'...they're gonna see that NHC track and think 'we're in the clear'


Agreed. Most people don't realize how large Irene is. Even if you look at the current forecast track, Irene is NOT that far off our coast. As I said, a 6-10hr prolonged WNW trek and the ballgame changes. 100 miles makes a big difference.

I DO NOT want this in any way shape or form. Had my fill of this crap in FL. But I am not breathing any sighs of relief either. I remember Charley very well. It was Tampa, Tampa and TAMPA for days! Then at the last minute (damn near) he turned and missed us by over 100 miles.

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Quoting vital1:
I just read on Twitter that Reed Timmer is taking the Dominator to try to intercept where Irene makes landfall. He said he's bringing a vertical radar. I'm usually a lurker, but thought y'all may find this interesting......or not:).



1,2,3....... Dominate!

Hope Reed finds success
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Quoting presslord:


me too...Mr Browning...12 guage, automatic...and about 1000 shells...they may get me...but I'm takin' some of 'em with me...
1000 shells, some of em? Don't you mean ALL OF EM' and den some....LOL Morning Press
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Looking like a Cat 3 moving into North Carolina then a Cat 2 to Cat 1 moving up the East Coast into New England. A large segment of the population will be affected by Irene along the East Coast.
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New low pressure just popped up with 20% chance of development on the latest TWO.
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TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT TUE AUG 23 2011

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE
IRENE LOCATED ABOUT 70 MILES SOUTH-SOUTHEAST OF GRAND TURK ISLAND.

SHOWERS AND THUNDERSTORMS NEAR A LARGE LOW PRESSURE SYSTEM LOCATED
ABOUT 750 MILES WEST-NORTHWEST OF THE NORTHERNMOST CAPE VERDE
ISLANDS HAVE CHANGED LITTLE IN ORGANIZATION. WHILE THE LOW IS
MOVING WEST-NORTHWESTWARD AT ABOUT 15 MPH TOWARD WARMER
WATERS...UPPER-LEVEL WINDS ARE FORECAST TO BECOME LESS FAVORABLE
FOR DEVELOPMENT. THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

A LARGE LOW PRESSURE AREA IS CENTERED ABOUT 300 MILES SOUTHEAST OF
THE CAPE VERDE ISLANDS. ALTHOUGH THIS SYSTEM IS NOT CURRENTLY WELL
ORGANIZED...UPPER-LEVEL CONDITIONS FAVOR SOME DEVELOPMENT DURING
THE NEXT SEVERAL DAYS. THIS SYSTEM HAS A LOW CHANCE...20
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES TO THE WEST AT ABOUT 10 MPH.


ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.



looks like we have 90L soon
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Quoting presslord:


me too...Mr Browning...12 guage, automatic...and about 1000 shells...they may get me...but I'm takin' some of 'em with me...


Singing to the choir, there, Press.
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BULLETIN
HURRICANE IRENE INTERMEDIATE ADVISORY NUMBER 12A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011
800 AM EDT TUE AUG 23 2011

...CORE OF IRENE HEADED TOWARD THE TURKS AND CAICOS ISLANDS AND THE
SOUTHEASTERN BAHAMAS...


SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...20.6N 70.6W
ABOUT 70 MI...110 KM SSE OF GRAND TURK ISLAND
ABOUT 55 MI...90 KM N OF PUERTO PLATA DOMINICAN REPUBLIC
MAXIMUM SUSTAINED WINDS...100 MPH...160 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...978 MB...28.88 INCHES
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I fully agree. Everyone at work is saying that it is going out to sea, I guess they are just used to re-curving storms. They don't need to panic, but they do need to stay informed, in case something changes. An example of this would be Jeanne.

Quoting presslord:


yup...the problem is gonna be gettin' people here to kepp watchin'...they're gonna see that NHC track and think 'we're in the clear'
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Quoting Supposetobefishin:


Or worse... some cheeky "so and so" fires up an ol Lawn Mower and pulls a fast one on ya Generator while your snoring...

(True story - heard after Ivan hit Cayman).
I can confirm that. Didn't happen to me but it did happen to many. I bought a very heavy chain and put 3 padlocks on it. Had mine in the shed with the door open.
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...CORE OF IRENE HEADED TOWARD THE TURKS AND CAICOS ISLANDS AND THE SOUTHEASTERN BAHAMAS...

8:00 AM EDT Tue Aug 23
Location: 20.6°N 70.6°W
Max sustained: 100 mph
Moving: WNW at 10 mph
Min pressure: 978 mb
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Quoting earthlydragonfly:

I have double barrel type of protection..  


me too...Mr Browning...12 guage, automatic...and about 1000 shells...they may get me...but I'm takin' some of 'em with me...
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Quoting HurricaneDevo:
So did this move east or west from yesterday?



Here is the 00Z (Previous Run) Looks maybe a hare further East..

00Z GFS
Member Since: December 18, 2006 Posts: 7 Comments: 2685
Stay safe Press...
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Quoting nash28:


I think this one is gonna be a nailbiter till 24-36hrs out. It's just not cut and dry. It could slam us right up the gut if the weakness isn't as pronounced. It could hit the OBX or it could possibly miss everyone (not likely).


yup...the problem is gonna be gettin' people here to kepp watchin'...they're gonna see that NHC track and think 'we're in the clear'
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Quoting msgambler:
Suppose, they better pack a lunch. Mine is protected be two German Shepards and bolted down to concrete, hardwired to the house. And, it better be a good freakin' lawn mower....LOL
I have double barrel type of protection..  
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Quoting earthlydragonfly:


With all of the rain they are getting right now.. Im not really sure they are catching a break. From the winds probably and surge probably... But the rain in the mountains is going to be a real problem with flash flooding and mud slides.


Concur. Haiti has a lot of people living at the base of largely deforested mountains. Any significant rainfall can be quickly converted into a deadly juggernaut of mud and water, racing to the coast. It can wipe out whole villages, or cut off the coastal supply routes. Once the rain stops, the new topography creates pools of standing water, just right for disease vectors.

I don't think there's anyone in Haiti who's feeling too good about Irene just because the imaginary line that the NHC drew didn't cross their landmass…
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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.