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 NasBahMan:


We in the Bahamas in the path of Irene are not looking for an eye.
We are thinking of you even as people say fish we all know you are there and in the path of a major event be safe!
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Irene: Happy now?
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Hurricane Hunters are closing in on the center:

As of the last observation at 13:58:30Z, the plane's...

Direction of Travel: WNW (298°)
Location: 88 miles (142 km) between the NE and ENE (56°) from Santo Domingo, Dominican Republic.
Member Since: December 18, 2006 Posts: 7 Comments: 2686
Quoting Bluestorm5:
Wish all of smart ones are on here... this blog is full of idiots except for TampaSpin/ncstorm


Quoth the teenager
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831. Vero1
Quoting Jax82:


Ugh, the XTRAP is still showing a Miami the NOLA landfall!!! (sarcasm flag ON)


Yep still heading toward Dallas,TX
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Quoting CaneHunter031472:


Therefore it is the United States. Gosh what they teach you kids in Kindergarden now days? To put a condom on a cucumber that's all?
Is it one of the actual 50 states?
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Quoting wolftribe2009:
I am going to kick myself in the rear if this storm misses the trough and plows into Florida and then into the gulf. I have been wanting to say that is what is going to happen but don't have any model support and every else is saying it is turning to; therefore, hey if i have to be wrong then it is better if we all are wrong and so I go with South Carolina Landfall.
we dont know yet,it may miss all but the islands.or??
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Quoting gator23:


Never mind that Puerto Ricans are American citizens by birth.


yep, this is very true.
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Nice blob.

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Quoting CaneHunter031472:


Therefore it is the United States. Gosh what they teach you kids in Kindergarden now days? To put a condom on a cucumber that's all?


actually, it's not the United States but somehow it's part of the United States. This issue is a bit complicated.
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824. Jax82
Quoting ProgressivePulse:
12Z TVCN shifted east to OBX.






Ugh, the XTRAP is still showing a Miami then NOLA landfall!!! (sarcasm flag ON)
Member Since: September 2, 2008 Posts: 1 Comments: 1261
Quoting ProgressivePulse:
12Z TVCN shifted east to OBX.






Good news... I have family in NJ/NY so I sure hope the westerlies would be strong enough and with the assistance of a decent TROF it should hopefully completely stay 50 to 100miles of the US E/NE coast, but I know there's a good chance it might want to ride the E US coast closer than that and very fast.
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Quoting CaneHunter031472:


Therefore it is the United States. Gosh what they teach you kids in Kindergarden now days? To put a condom on a cucumber that's all?


Never mind that Puerto Ricans are American citizens by birth.
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Quoting WxLogic:


No problem. Capable yes however, they can't fly as low as the CJ's which is why they are more valuable at the upper levels.
Member Since: August 19, 2005 Posts: 5 Comments: 5405

We have an eye! Or is it...?
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Quoting Bluestorm5:
Found the youtube video of Katrina's life. I was right, it didn't formed an eye until it was Category 3. Video: Link


Way wrong. Katrina had an eye when she made landfall over florida see link below.

http://www.weather.com/outlook/weather-news/news/ articles/trop-katrina-aug25-diary_2010-08-17
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Quoting Matt74:
Puerto Rico is not the united states. I'ts a territory of the US.


Therefore it is the United States. Gosh what they teach you kids in Kindergarden now days? To put a condom on a cucumber that's all?
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Quoting ProgressivePulse:
12Z TVCN shifted east to OBX.







there you go !!!
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Quoting MahFL:
Actually I think Irene jogged WSW, so there !

She's taking in some inflow off the mountains.
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Quoting BahaHurican:
There is a press conference at 10:30a.m. EDT for NEMA, which is our emergency agency. I guess they are going to open shelters in Nassau today.

A location of 524 miles to the SE of Nassau, moving at 10mph means Irene should be here by Thursday morning.
Are you in Nassau baha?
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I am going to kick myself in the rear if this storm misses the trough and plows into Florida and then into the gulf. I have been wanting to say that is what is going to happen but don't have any model support and every else is saying it is turning to; therefore, hey if i have to be wrong then it is better if we all are wrong and so I go with South Carolina Landfall.
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12Z TVCN shifted east to OBX.




Member Since: August 19, 2005 Posts: 5 Comments: 5405
Also larger a major hurricane is, the higher storm surge goes. That's why Katrina was so bad...
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810. ackee
THE model seem to shfting again would be suprise if it just skirt up the US east coast
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Quoting ProgressivePulse:

Thanks for the read... very interesting and surprising to me the G-IV was actually capable.
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Quoting NortheastGuy:
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?


true but the further west it wobbles the more likely it will be for it to hit the US. Irene right now is on a track further south than any storm to hit the Carolinas in the last couple decades. That is why I am not so sure it is going to NC but am more leaning on a landfall in South Carolina (likely near Charleston).
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807. MahFL
"CHICAGO (Reuters) - Forecasters on Tuesday warned residents of Illinois and Indiana to brace for possibly severe afternoon weather as a cluster of powerful thunderstorms pushes eastward out of Iowa."

Hmmm, that sneaked up on me.

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Quoting BahaHurican:
There is a press conference at 10:30a.m. EDT for NEMA, which is our emergency agency. I guess they are going to open shelters in Nassau today.

A location of 524 miles to the SE of Nassau, moving at 10mph means Irene should be here by Thursday morning.


check you're WU mail
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Quoting Thoroside:
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.
Been wondering the same thing. Good question.
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Quoting Matt74:
Puerto Rico is not the united states. I'ts a territory of the US.



somehow correct.
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Quoting CoopsWife:


Bayside - NOOOO, say it isn't so..... Seriously, take care and get your prep done. I'm taking the baby girl off to college (GMU) on Thursday, back after midnight, so I'm working my yard now. All these trees (and can't cut a single one - you and I are in the same boat with the CBP Act) - anyway, I'm prepping early and have reservations in place for a possible run to the west. May have to shift farther west if the track holds.


Yeah, I got some trees I worry about and the boats especially when we decide to leave, but if there is surge I can't do anything if they break their lines anyway except watch since I wouldn't be able to get to them, so maybe it's better that way. I have some friends offering places from Newport News to Richmond, so we'll see what it looks like wed/thurs I guess. Earl last year was a stressful event and it turned out to be nothing, but I want to be ready in case this one doesn't spare us.
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Quoting BahaHurican:
There is a press conference at 10:30a.m. EDT for NEMA, which is our emergency agency. I guess they are going to open shelters in Nassau today.

A location of 524 miles to the SE of Nassau, moving at 10mph means Irene should be here by Thursday morning.


Not good baha...

Hoping it decides to turn and head towards Greece... but hang in.
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801. MahFL
Actually I think Irene jogged WSW, so there !
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Found the youtube video of Katrina's life. I was right, it didn't formed an eye until it was Category 3. Video: Link
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LETS ALL HOPE WE DON'T GET A 'KATRINA' SIZE STORM

I can remember how Katrina was so large that her storm surge caused damage over a 100 mile area of coast line.
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Quoting TampaSpin:
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.


I agree 100% Current Observations trump models daydreaming any day.

Models did not show this as strong right now. Once they pick up on the strength they will keep on pushing the track EAST. This current pattern over the northern US has been pulling punches on the models with stronger than forecasted disturbances over the last 10 days, and it continues as of this morning.

So far the tends are very good for a miss on a direct hit on the CONUS.
Member Since: June 5, 2008 Posts: 0 Comments: 51
Quoting Patrap:


Eye starting to form.
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Charley did a right wobble and went in 60-80 south of forecast
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Quoting alvarig1263:


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.


This is the information people should use to determine who's in or who's out.

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Well you can tell where the bulk of the people are from this forum....Slow moving.....right now:)
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There is a press conference at 10:30a.m. EDT for NEMA, which is our emergency agency. I guess they are going to open shelters in Nassau today.

A location of 524 miles to the SE of Nassau, moving at 10mph means Irene should be here by Thursday morning.
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Quoting ecupirate:
Anyone else find it strange that this storm has been a hurricane for nearly 24 hours and has yet to form an eye?
She technically has an eye but it's not visible.
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790. MahFL
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.


You must not have been here long, we always wishcast west !
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Quoting Methurricanes:
It already made landfall in the US as a Hurricane Pueto Rico is the United States, so its impossible to miss the united states because it already hit it.
Puerto Rico is not the united states. I'ts a territory of the US.
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Click for enlarged image.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Katrina's eye was clearly visable on Miami radar as she made landfall
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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.


Thanks for wishing that on us!
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Storm Relative 1km Geostationary Visible Imagery


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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.