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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Quoting KEEPEROFTHEGATE:
don't worry coopswife just like a bad case of the cramps he will pass and be nothing more than a stain on some toilet paper


LMAO!!
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no update
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Quoting KEEPEROFTHEGATE:
don't worry coopswife just like a bad case of the cramps he will pass and be nothing more than a stain on some toilet paper

Yeah, the short bus will be by any moment to whisk him off to his very special kindergarten, and all will be calm again. In the meantime, report and ignore. Please.
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out of date no update
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#112

Congrats, I've heard Admin has a special surprise for you!
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Quoting farupnorth:


All depending on how low the trough digs down and grabs her. Imagine if she had been higher earlier the ridge would have provided swifter steering to the west.

Seems the early models predicted a swifter steering altogether.

My take is when she clears Hispaniola to the south she will strengthen fast, gain latitude and feel the trough more (when it arrives)

Alot of factors but now it seems most models trending east.




The trough is already there. It is a shortwave that is supposed to reinforce the trough in the Thursday time frame that will be the one that pulls her out. According to a local met in our area that posted yesterday. That said, if she travels slower then it will take longer for her to feel the effects of the shortwave. Thus traveling further west before that happens.

Again, this is why the slower HWRF, GFDL, and even Ukmet models are further west than the faster GFS. At least this is my basic understanding of the setup and steering right now.

CW - I'm fueling up for Avionics class which I have to be at in about an hour. The rest of the crew will have to hold the fort down until morning.
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Quoting tkeith:
Kinda looks like it's puttin the brakes on a bit...



It does doesn't it. Sure hasn't been moving at 12mph..
Member Since: December 18, 2006 Posts: 7 Comments: 2685
Oh Keeper that was low! Good but a little low! Lol
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Wow!! A cat 4 in the Bahamas!!
Praying for our friends in the T&C and in the Bahamas! Keep going East Irene!! please!!!!!!!! No one needs to feel your full power.
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Quoting KEEPEROFTHEGATE:
don't worry coopswife just like a bad case of the cramps he will pass and be nothing more than a stain on some toilet paper


LOL!!! Did someone say breakfast.. im starved... 2 overeasy, toast, blackberry jelly, bran muffin, fruit, and a cup of mango juice. :-)
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SJ - think the breakfast layout got left behind on the last page -


Coffee/juice

Bacon/Blueberry pancakes (and yes, those are fresh blueberries

Fresh sliced peaches and cream (or half and half for the dieters)

Dig in and fuel up so you can keep working on the storm data.
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don't worry coopswife just like a bad case of the cramps he will pass and be nothing more than a stain on some toilet paper
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Thanks CW, breakfast would be great :)

This one is very reminiscent of the infamous ST...
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Kinda looks like it's puttin the brakes on a bit...

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Gosh - may have to spend and hour or so with the plus and minus keys today just to be able to filter, LOL.

It does, indeed look as if SE VA will see something out of this. Hmm - taking the youngest off to college in Northern VA Thursday - then back to Yorktown to drop off the L&M. After that I do believe I may swing home to VA Beach, gather up the critters and head WEST on a road trip, LOL. Too many centuries old oaks around the house to play games with hundred mile an hour winds.
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Quoting StormJunkie:


See my previous post about timing. According to GFDL/HWRF, slower would actually mean a more southern and further west landfall from what I can tell.



All depending on how low the trough digs down and grabs her. Imagine if she had been higher earlier the ridge would have provided swifter steering to the west.

Seems the early models predicted a swifter steering altogether.

My take is when she clears Hispaniola to the south she will strengthen fast, gain latitude and feel the trough more (when it arrives)

Alot of factors but now it seems most models trending east.


Member Since: August 4, 2010 Posts: 0 Comments: 131
06Z GFS track is very similar to 00Z, but a little faster.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Quoting howtheweather:
WRONGAAIN , WHAT GARBAGE WERE ALSO MY OLD NAMES I KEPT GETTING BANNED SINCE 2 WEEKS AGO BECAUSE OF RUNNING MY MOUTH ABOUT FLORIDA WONT GET HIT AT ALL AND THEY KEPT BANNING ME SO MAKE ANOTHER NAME BOTTOM LINE IS I HAVE 100% RIGHT SINCE LAST WEEK THEY DO THIS EVERY YEAR TO BOOST SALES FOR HOME DEPOT AND WALMART


I have a big cup of shut the *&^% up... waiting for you here in my kitchen :-)

Do you take creamer and sugar?
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Quoting StormJunkie:
Morning CW :) Good to see you!

It's never completely safe in here. As you can see; apparently Irene is not real...It's been fabricated by Home Depot & Lowes...lmao


LOL!
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Hey Storm Junkie -

Yes - been lurking for MONTHS this year - but looks as if Irene will be knocking more darned branches off my 'self pruning' water oaks!!

Thought I might at least serve breakfast to the night crew when I checked in this morning. :)
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Quoting NICycloneChaser:
The GFS 06Z at 51 hours out as Irene slightly farther north than at 00Z. However, the 06Z seems to have the trough progressing eastwards and lifting out slightly faster than the 00Z. This could act to give a more easterly track, but it could also allow the ridge to build back in more quickly, nudging Irene further west. All about timing, as usual.

00Z:



06Z:



The trough does not appear as deep either and the ridge looks a stronger
Member Since: August 14, 2007 Posts: 0 Comments: 535
09L/H/I/C3
RI FLAG (flag)
MARK
20.25n/71.00w






ALWAYS FOLLOW NHC/TPC FORECASTS FOR ALL WARNINGS REGARDING THIS STORM
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Morning CW :) Good to see you!

It's never completely safe in here. As you can see; apparently Irene is not real...It's been fabricated by Home Depot & Lowes...lmao
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Quoting howtheweather:
THEY HAD IRENE HITTING THE KEYS THEN MIAMI THE GOING THROUGH FLORIDA THEN WEST PALM THE ALL ALONG THE FLORIDA EAST COAT THEN GEORGIA THE S CAROLINA THEN NORTH CAROLIN AND IT WONT DO ANYTHING BUT GO OUT TO SEA JUST KEEP PLAOT AND WATCHING THE NEW CHANGES AS THEY DO EVBERY YEAR WALMART AND HOME DEPOT ARE SPONSORS OF THE WEATHER CHANNEL


How do you know this is your 2nd comment ever posted on these forums.....

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105. MahFL
Are those max winds Rob posted gusts or sustained ?
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Quoting StormJunkie:


There is no such thing as "pumping the ridge"...It is a made up term by a farce. ;)


Oh.. opps look like they got me. lol I didnt know.

Thanks
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Quoting howtheweather:
LIKE I HAVE BEEN SAYING EVERYDAY SINCE LAST THURSDAY FLORIDA WILL GET NOTHING FROM THIS STORM I HAVE BEEN 100% RIGHT....


You joined Sunday the 21 of this month, Thurday was the 18...
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Quoting howtheweather:
I SAID OVER 40 TIMES SINCE LAST WEEK SINCE LAST WEEK THIS STORM WILL SLOWLY GO OUT TO SEA AND ITS ALL A PLOT TO BOOST SALES FOR HOME DEPOT AND WALMART IN AS MANY PLACES UP THE EAST COAST AS THEY CAN THEY DO THIS EVERY YEAR CHANGE L;ANDFALL 40 TIMES TO BOOST SALES AND AS USUAL IM RIGHT AGAIN


Disagree -1 point for you sir.
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Sidling in - checking traffic (is it safe in here this morning??)

Coffee and juice on the breakfast bar, bacon and blueberry pancakes coming up.

Hmmm - looking more and more as if we'll get enough from Irene to damp out the fires in the Great Dismal Swamp this weekend.
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Quoting BenBIogger:


that 2nd trough looks a little shallow, maybe won't amplify as much as the models are showing...esp the GFS
Member Since: August 14, 2007 Posts: 0 Comments: 535
Recon is up.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Quoting TampaBayWX:
whats it mean when people say Irene is "pumping the ridge"????

Does this mean just bouncing off it or riding along side?


There is no such thing as "pumping the ridge"...It is a made up term by a farce. ;)
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whats it mean when people say Irene is "pumping the ridge"????

Does this mean just bouncing off it or riding along side?

Im new to all this weather stuff....
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Quoting farupnorth:


Moving much slower than originally forecast. More and more looking like it will recurve before east coast.

But as stated many times Bahamas will not be as lucky.


See my previous post about timing. According to GFDL/HWRF, slower would actually mean a more southern and further west landfall from what I can tell.

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Quoting TampaBayWX:


Poor Bahamas, when was the last time they took a Major hit?

Well, 1999's Floyd was pretty nasty to them, and there have been many others. The worst one there was the Hurricane of 1929. If the path and intensity of Irene are what they have the possibility of being, this could be just as bad as that for them.
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Quoting NICycloneChaser:
The GFS 06Z at 51 hours out as Irene slightly farther north than at 00Z. However, the 06Z seems to have the trough progressing eastwards and lifting out slightly faster than the 00Z. This could act to give a more easterly track, but it could also allow the ridge to build back in more quickly, nudging Irene further west. All about timing, as usual.

00Z:



06Z:



Yep, it is all about timing from what I can tell. If you notice; the HWRF & GFDL (current western outliers) are slower than the TVCN & GFS which are on the eastern side of guidance. Hopefully the rest of today's runs will iron this out some.
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Quoting TampaBayWX:


Poor Bahamas, when was the last time they took a Major hit?


Jeanne for the northern Bahamas, Frances for the southern islands.
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Wow She is turning into a monster. Bahamas is going to be in trouble. I hope they are preparing.
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Quoting Neapolitan:

It would certainly appear so. With the more or less steady eastward movement of each succeeding forecast track, we may see the center of the five-day cone out in the open sea by this evening or the morning. A US landfall has shifted from the southern tip of Florida up the east coast to Miami, then Palm Beach, then Jacksonville, then Savannah, then Charleston, and--now--Wilmington. Of course, some of that is an illusion, as the cone narrows with time. But, still, the eastern migration is evident. Cone animation here.

At any rate, what is becoming more and more certain is that the Bahamas are in for as nasty a walloping as they've likely ever seen...


Moving much slower than originally forecast. More and more looking like it will recurve before east coast.

But as stated many times Bahamas will not be as lucky.
Member Since: August 4, 2010 Posts: 0 Comments: 131
The GFS 06Z at 51 hours out as Irene slightly farther north than at 00Z. However, the 06Z seems to have the trough progressing eastwards and lifting out slightly faster than the 00Z. This could act to give a more easterly track, but it could also allow the ridge to build back in more quickly, nudging Irene further west. All about timing, as usual.

00Z:



06Z:

Member Since: August 10, 2010 Posts: 2 Comments: 1971
Quoting Neapolitan:

It would certainly appear so. With the more or less steady eastward movement of each succeeding forecast track, we may see the center of the five-day cone out in the open sea by this evening or the morning. A US landfall has shifted from the southern tip of Florida up the east coast to Miami, then Palm Beach, then Jacksonville, then Savannah, then Charleston, and--now--Wilmington. Of course, some of that is an illusion, as the cone narrows with time. But, still, the eastern migration is evident. Cone animation here.

At any rate, what is becoming more and more certain is that the Bahamas are in for as nasty a walloping as they've likely ever seen...


Poor Bahamas, when was the last time they took a Major hit?
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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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