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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Storm Relative 1km Geostationary Visible Imagery


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Irene is still getting bigger.



On a serious note, even if Irene curves and misses a US landfall, the whole coast from Miami to Cape Hatteras could experience TS conditions.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Ok......its almost 10am........time to get off here as the crazies are coming it appears.......LOL! Have a good day! Might be wrong, but that next trough seems a little stronger currently.......I don't believe Irene will directly hit the ConUs at all Currently thinking. Its just my opinion tho.
Member Since: September 2, 2007 Posts: 178 Comments: 20439
782. A4Guy
I'm just waiting for someone to insist the storm is moving SouthEast!!
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Quoting Orcasystems:




Bird is fixed and feet wet again



"What do you mean you forgot to gas up the plane?"
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come on guys. Irene is on track and not moving due west.
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Quoting BobinTampa:



DUE WEST!!!!!

I can't wait until this storm 'misses the turn' by 1000 feet. That will bring the Florida folks back in droves.


Morning all..

I pointed that out yesterday... that if the storm doesn't turn 15 minutes or a mile west of the forecast point... people would flip out.

You may have a more accurate model though... 1000 feet sounds about right.
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Quoting BobinTampa:



DUE WEST!!!!!

I can't wait until this storm 'misses the turn' by 1000 feet. That will bring the Florida folks back in droves.
once Irene passes 78 W,there will be carnage in here.....lol
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Member Since: August 19, 2006 Posts: 13 Comments: 14234
A few weeks ago many on this bloG were saying what a dead season, with weak TROPICAL STORMS , the majority coming from non tropical entities. now it only takes one(IRENE) to change all of that. The season is still young, and as soon as IRENE is no more , there is Jose to contend with next week. COULD BE ANOTHER MAJOR
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773. Jax82
Quoting CaneHunter031472:
12z Early Cycle NHC model tracks

Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)


Dynamic Models (More sophisticated models)


East she blows, lets hope if she is going to impact the east coast its with her left side, then out to sea.
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I think Katrina was the last storm that didn't formed eye as a Category 2... but I can't find a proof.
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Quoting Bluestorm5:
Wow, people are freaking out because it wobble to west... it's been wobbling west and northwest everyday since Irene formed. It's moving WNW at average.

i don't really see anyone freaking out. just observing. you are right it is moving wnw, but a good wobble can throw a storm off course by a few hundred miles. i don't think we are looking at a gulf storm unless the high does something really drastic, but florida should still be watching.
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Bird is fixed and feet wet again
Member Since: October 1, 2007 Posts: 81 Comments: 26511
NAM intitializes with a slight bit stronger ridging to the north of Irene compared to the 06 and 00UTC runs.
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Quoting presslord:
We will be having a conference call this evening at 8pm EDT to discuss Portlight's response to all this. We will focus tonight on how we may be of assistance to our friends in the Bahamas and T & C islands. If you'd like to join, please WU mail me and I'll send you the call in # and participant code.
Bouncing this to the top Thanks so much Press for all you do!
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Quoting HCW:
What are your thoughts on that blow up of convection off the frontal boundary on the east coast and if a surface low forms what would it do to Irene


Fujiwhara effect!

Watch out Miami...... ;-)
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766. maeko
Dear Irene: no one likes a "squatter"!
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Quoting niederwaldboy:


aren't these jog's west just wobbles??


The wobbles add up. And if Irene goes west of a certain longitude then Florida may need to be concerned. But so many other factors going into where Irene will go too. Bottom line, no ones out of the woods yet.
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As of the last observation at 13:38:30Z, the plane's...

Direction of Travel: WNW (298°)
Location: 83 miles (134 km) to the W (278°) from San Juan, Puerto Rico (USA).
Member Since: December 18, 2006 Posts: 7 Comments: 2685
Good morning everyone!!!!!!!! So how is our little friend doing this morning??? which way is she moving??
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12z Early Cycle NHC model tracks

Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)


Dynamic Models (More sophisticated models)
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Honestly here to learn, that said, can I ask about the pattern of the past two years. For two years now, we've heard from experts that the Atlantic Ridge will be firmly in place to push storms to the west on a beeline. We've heard that FL and the Gulf states are a sitting duck, etc etc.

Now, for the past two years, most every storm to approach we have now seen curve sharply north or a full re-curve. And in this case with Irene, I read from experts that, that was mostly due to the shortwaves skirting down, and not the deep East coast trough (which to an amateur myself would be more understandable). How is that, any little mild influence in the northern North American atmosphere is defeating this once proclaimed dominant Atlantic ridge?

I'd love to here some opinions and facts on the matter. Thanks guys.
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A bad day at the office for the Doctor!!!

Link

Link

Debris lies waist-deep in the galley after the penetration of Hugo's eyewall.
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Quoting Nolehead:
oh my bad gator23, was talking in general... wasn't going by the map..I should have said so...but i'm sure there are many that we can't all remember also..

I was agreeing with you. I never let my guard down until landfall...
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Quoting alvarig1263:


Definitely, Florida watch out!!


aren't these jog's west just wobbles??
Member Since: January 31, 2006 Posts: 0 Comments: 100
Quoting Bluestorm5:
Wow, people are freaking out because it wobble to west... it's been wobbling west and northwest everyday since Irene formed. It's moving WNW at average.



DUE WEST!!!!!

I can't wait until this storm 'misses the turn' by 1000 feet. That will bring the Florida folks back in droves.
Member Since: August 14, 2008 Posts: 0 Comments: 527
756. HCW
What are your thoughts on that blow up of convection off the frontal boundary on the east coast and if a surface low forms what would it do to Irene
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the more it stays unorganized "as crazy as that sounds giving it's a 100 mph storm" the features are getting better but it's like a HUGE TS, granted i know it's a cane, just sayin it might just be the reason for the west jumps... lot of time left for her to do her thing..whatever it might be..
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Quoting BahaHurican:
Morning everybody.
Good morning Baha..Hope preparations are going ok for you & family/ friends there.
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Looks like Irene is getting almost far enough from land to clear up her circulation. I wonder what the most powerful storm to NOT have an eye has been?

The models started with a path much further south, and have continually shifted eastward. I can't help but think that some of this is due to high sensitivity to latitude in the steering currents, coupled with some land interaction that prodded Irene a bit more northward than she wanted to be.

If so, then now that she's clear of land and with models nicely initialized with G4 and balloon data, the paths should stabilize. I can't help but wonder if she'll bump a little to the S and W as she gets an unshrouded moisture feed from the S before Cuba. A path bump back to the W may yet occur?
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It's amazing to watch the "Knee jerk reactions" on every wobble north or west. Last thing I heard - hurricanes don't travel in straight lines. A jog west and some will say it's heading for South Florida. A jog north and others will say it's going out to sea.
I thought it took time for 'Tracks" to pan out?
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Wow, people are freaking out because it wobble to west... it's been wobbling west and northwest everyday since Irene formed. It's moving WNW at average.
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Quoting WxLogic:


Jets have a higher turbulence penetration speed than prop planes to ensure structural stability. Prop planes are easier to maneuver and have far better structural stability for such (not all prop planes of course, but those made for such severe/demanding) conditions.


On July 29th, 2005, the St. Petersburg Times ran an article criticizing NOAA’s use of Gonzo. According to the piece (by Paul de la Garza), NOAA changed the mission parameters of the Gulfstream; instead of flying close to hurricanes (which the planes had been doing since 1996), the union said the aircraft now flew through hurricanes. That’s risky enough; NOAA’s union (the National Weather Service Employees Organization) said that Gonzo’s manufacturer (Gulfstream) hadn’t certified the aircraft to fly through hurricanes and that the plane doesn’t have the proper radar for hurricane flying. Citing safety concerns, the NWSEO filed a complaint on July 26th, 2005 with the Federal Labor Relations Authority claiming that NOAA hadn’t consulted with the union members before instituting new policies that the union felt put its workers in harms way (by the way, the pilots aren’t NWSEO union members, just the meteorologists flying on board). At the time of the complaint, the NWSEO said Gonzo had already flown through 2005’s Hurricane Emily and Tropical Storm Franklin; NOAA in turn claimed said the aircraft flew above the storms.



Testimony into the matter started on February 1st, 2006. On June 30th, 2006, Federal Labor Relations Authority Judge Richard Pearson sided with the union and ordered NOAA to stop flying the Gulfstreams into storms until the government and the union came to an agreement. The ruling did not affect the G-IVs mission to fly around storms, just not through them. By the way, the Kessler WC-130Js fly with a crew of six; the P-3s fly with a crew anywhere from seven to seventeen people. And while a WC-130J costs around $22 million, a P-3 goes for around $36 million (although the last new P-3 was built in April of 1990).



On September 16th, 2005, NOAA unveiled a new Hurricane Hunter- an unmanned flying drone. The Aerosonde has a wingspan of 9.51 feet, cruises up to 93 mph and has a range of 1,864 miles. NOAA, NASA and Aerosonde developed the vehicle to not only provide support to the manned missions of the Hurricane Hunters, but to also do something the P-3s and Gulfstream can’t do: fly lower.
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Quoting medic2luv:
Dear Irene,
Please develop an eye so we can all track you easier.
Thanks


We in the Bahamas in the path of Irene are not looking for an eye.
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06z Latest GFS Ensemble Member Tracks

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baha,if you are in the bahamas,what island are you on? if ya dont mind my asking
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Quoting sarahjola:
thanks for posting that map. that was just what i was looking for. can you post some more for predicted and current. tia! what do you think irene is going to do?


It's honestly really hard to say, it all depends on the series of shortwaves that follow. If they are deeper than projected the path will be out to sea. If they are more flat (zonal) it would be further west. That's why there is still quite a bit of spread in the models, cause they are having a hard time getting a handle of the overall amplitude of these shortwaves. As long as Irene continues to move slow, that is an indication that she is in weak steering currents. I think the next time she resumes a faster forward motion you should be able to get an idea where she is going. At least a ballpark.

EDIT: On a side note, rapid intensification in the short term would almost guarantee a more easterly track.
Member Since: December 18, 2006 Posts: 7 Comments: 2685
a good wobble can push a storm off its track a few hundred miles sometimes
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Looks like Irene just sucked in another gulp of warm, dry air descending from the higher terrain of the Dominican Republic. Inner core will suffer for a bit, but she should RI later this afternoon or evening as she finally pulls away DRs influence.
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Quoting BahaHurican:
Morning everybody.


gm baha, ready for a busy day?
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This 2nd trough looks stronger than the first.......i don't believe the ConUs mainland will get hit directly now.......LOok at this link.......http://www.atmos.washington.edu/~ovens/loops/wxlo op.cgi?wv_east_enhanced+12

It is a large file so give it time to load.
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Dear Irene,
Please develop an eye so we can all track you easier.
Thanks
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Quoting prweatherwatcher:
Tornado warning, Flash flood everywhere, power outage Irene GO AWAY Dann Storm let PR back to normal life.
Good to hear from you glad you are safe and hope Irene leaves you all alone be safe!
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Quoting E46Pilot:


SE FL rarely gets hit with storms. At least it's been that way for the last 30 years. We've only got hit with 3 storms that have caused major headaches. David, Andrew, and Wilma.


Thus, very roughly once per decade for a major cane (David may have been a 2?).
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HH Airborne
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Last few satelite frames show Irene a little less organized in the coc. I keep waiting for it to produce an eye, but has yet to do so.

There was a slight wobble to the west in the last frame, but its just a wobble (Sorry florida doom casters)
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Quoting overwash12:
You should be fine according to the Track then,we will see how this plays out here in Knotts Island,N.C.


Rootin for ya big time!
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Gusting upto 40 on the TCI's

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

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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.