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 overwash12:
I thought it was Hugo.


it was
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Quoting Thundercloud01221991:


your model graph that shows the intensity forecasts is what I am talking about it starts out at 85 mph on the left of the graph but the current intesity is 100 mph


That is from WEatherUnderground.........those are the windspeeds that was input into the system the time the Windspeed models forecast came out........i'm sure they will be updating soon one would think!
Member Since: September 2, 2007 Posts: 178 Comments: 20439
632. MahFL
Jog left anyone ?
Member Since: June 9, 2004 Posts: 0 Comments: 3462
Quoting cat5hurricane:
Didn't Dr. Masters fly into Gilbert in 1988. Hey, if they can successfully complete a recon mission through that, I'd say there pretty damn reliable.

Nuff said :)
I thought it was Hugo.
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Quoting cat5hurricane:
Didn't Dr. Masters fly into Gilbert in 1988. Hey, if they can successfully complete a recon mission through a massive category 5 hurricane like that, I'd say there pretty damn reliable.

Nuff said :)


True enough.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Quoting FLWeatherFreak91:


If anyone thinks Haiti's "in the clear", remember that in 2004, Jeanne sat off Haiti's northern coast as a TD/weak TS.

The resulting floods killed over 3,000 people.

I can't imagine Irene in that same position is going to be any better…
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I was wondering the same thing. same as last year?

That could change though with the upper level pattern change soon
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Quoting FLWeatherFreak91:

This is Jeanne BEFORE she did the loop-de-loop and fujiwhama'd us! At this point, we opened our shutters from Frances--just to close them all again for Jeanne--28 windows, 7 doors and 3 garage doors to be braced. Takes a whole day to complete the task--this is why I am keeping a sharp eye on Irene--need lead-time!

Who'd a'thought--2 exact landfalls within 3 weeks? Thanks for the (bad) memories.
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Quoting kshipre1:
strange how it is August 23 and only 1 AOI out there in the atlantic.

I would things would pick up. just saying it is strange


1 AOI???? There are 2 invests and nearly a major hurricane.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Quoting TampaSpin:


There was a shift to the west slightly late yesterday evening by many ......but, they came back late last nite and early this morning....
,how many times a yr do we here this is a floridia storm the last couple years and they go poof,towards the yucatan or out to see,dam we have good wx!!!
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Quoting Grandpato4:


I have family in Raleigh and I'm confident their house is safe. It is all brick with no large trees around us. I am still hoping and praying for a turn out to sea.



I am hoping for that turn too Granpa. I will just be glad for NHC to be on board with it. The models this morning are looking better for us fortunately
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Quoting presslord:


and I can't for the life of me understand why that fact would not be glaringly obvious...


It is glaringly obvious, and I know that that is why they have problems, I was just commenting on the fact that they seem to have had more problems this year than in other years.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Now is the time to fill up the car plus other gas tanks before the lines and shortages start.
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Link

Just got in recon info.
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Quoting Smikey:
Ok I think its safe to assume every post talking about “out to sea” or “fishstorm” is in reference to CONUS. Ya we know, it’s made landfall on the US down in PR and could very well make havoc in the Bahamas.


Agree,,,,,,,i know i do the same as i don't look in the pass once a storm has impacted.......i look what is next in reference. I think many do the same while some do their best just to try to make one sound like they don't care.
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Current steering level:



Next steering level (Cat3):



You can noticed on the above that a northerly component to Irene's motion is definitely possible in the short term as the weakness still quite open.

Yet currents are not moving things along it too fast as you can see in the WV SAT Loop.

In the image below, you'll see that Irene is elongated N to S and not "circular" in appearance which tells you that is attempting to get into that weakness but since it's so large it requires assistance to displace it from point A to point B. The yellow line represents a COL region or an area of low steering between a High and Low pressure.



Irene would continue to move slowly but the window is open for now for a more Northerly component if it wanted to.
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Seriously people???
Member Since: January 31, 2006 Posts: 0 Comments: 100
Tornado warning, Flash flood everywhere, power outage Irene GO AWAY Dann Storm let PR back to normal life.
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Quoting charlottefl:


They're actually very reliable, but you have to think of the conditions they fly in, you don't want to continue on a mission into a strong hurricane with mechanical issues.


and I can't for the life of me understand why that fact would not be glaringly obvious...
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Quoting belizeit:
This is a image of a rare tornado that TS Harvey spawned in Belize
Good God, that's massive. EF3-4 equivalent?
Member Since: August 11, 2010 Posts: 0 Comments: 776
Quoting FLWeatherFreak91:
,big differnce in steering when your talking about the differnce between a ts and a cat 4,a jeanne type scenrio has 99% chance of NOT happening
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strange how it is August 23 and only 1 AOI out there in the atlantic.

I would things would pick up. just saying it is strange
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Quoting Orcasystems:


Let see.. you take an AC... run it thru bad weather and beat the living Bejesus out of it.. and yes... they have a tendency of having mechanical failures... go figure.


I know, it's a tough life for them, I was just commenting on it.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Maybe this year will be the year of the troughs!
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Quoting NICycloneChaser:


First one went home. Must have had mechanical problems. These aircraft seem far from reliable.


If you think that now, just wait until the funding gets cut further this fall. There's only so much maintenance money to go around....
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Quoting TampaSpin:


That is the forecast Windspeed for the next landfall hit....


your model graph that shows the intensity forecasts is what I am talking about it starts out at 85 mph on the left of the graph but the current intesity is 100 mph
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grandpato4 have a grouper granwich at shark shack for me!
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Quoting NICycloneChaser:


First one went home. Must have had mechanical problems. These aircraft seem far from reliable.


Let see.. you take an AC... run it thru bad weather and beat the living Bejesus out of it.. and yes... they have a tendency of having mechanical failures... go figure.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
IRENE IS FORECAST TO BECOME A LARGER THAN AVERAGE HURRICANE. IT IS
IMPORTANT TO REMIND USERS NOT TO FOCUS ON THE EXACT FORECAST
TRACK...ESPECIALLY AT DAYS 4 AND 5...SINCE THE MOST RECENT 5-YEAR
AVERAGE ERRORS AT THOSE FORECAST TIMES ARE 200 AND 250 MILES...
RESPECTIVELY.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Quoting stillwaiting:
whas hapn'n brotha from anotha motha??,no tc for us,suprise,suprise!!!,curious what models did you see shift west,pretty sure all have moved east over the last 24hrs,im expecting a fish,except for the bahamas...


There was a shift to the west slightly late yesterday evening by many ......but, they came back late last nite and early this morning....
Member Since: September 2, 2007 Posts: 178 Comments: 20439
2 models go right over my House, time to get water.
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Quoting NICycloneChaser:


First one went home. Must have had mechanical problems. These aircraft seem far from reliable.


They're actually very reliable, but you have to think of the conditions they fly in, you don't want to continue on a mission into a strong hurricane with mechanical issues.
Member Since: December 18, 2006 Posts: 7 Comments: 2686
Ok I think its safe to assume every post talking about “out to sea” or “fishstorm” is in reference to CONUS. Ya we know, it’s made landfall on the US down in PR and could very well make havoc in the Bahamas.
Member Since: June 5, 2008 Posts: 0 Comments: 51
Quoting Thundercloud01221991:


how can that be right ... on the left it says that wind speed is in mph but the winds at at 100 mph not 85 so is the winds really supposed to be in knots there?


That is the forecast Windspeed for the next landfall hit....
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Quoting CarolinaBeachGirl:
kb8cane. Best thing you can do this morning is calm down --I DO understand. You can see from my name where I am and hard not to be in dither. Clear heads needed to make good choices. IF any doubts---take your son and go to one of the shelters.

In the meantime try and prepare you home as best you can. The worst part is the wait. I am hoping she moves more east and the center stays over water and we get the easier side:-)
To be honest, at this point---TS conditons would be considered a gift!!

County EM should start a ramp up soon----pay close attention to them---what they have to advise and are going to be doing. Blog here is great for general info--have to pay attention for US right here-----

I am a vet of these storms and while it doesn't make it much easier---I will be glad to help you in anyway I can-----BAD to be alone with a young man to take care of----




Excellent advice!
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Quoting nrtiwlnvragn:
Looks like a different HH plane is now trasmitting HDOB


000
URNT15 KNHC 231259
AF302 0809A IRENE HDOB 01 20110823


First one went home. Must have had mechanical problems. These aircraft seem far from reliable.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Quoting TampaSpin:
IN MODELS I TRUST........They have done an excellent job thus far as a big picture. We tend to all look at the long term outlook when really anything beyond 3 days just can't be trusted. I see the models shifted to the East overnite after moving West slightly yesterday.
whas hapn'n brotha from anotha motha??,no tc for us,suprise,suprise!!!,curious what models did you see shift west,pretty sure all have moved east over the last 24hrs,im expecting a fish,except for the bahamas...
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Quoting AllStar17:


Those models on the right aren't exactly great (BAMS, AEMN, etc.)

The consensus still very much favors direct impacts unfortunately.



Yes, they do however, they are "trending" right. The only model left of the forecast track ATM is the UKMET and not by much. That is a big change from last night with the GFDL, HWFR & UKMET all left. NHC shifted east and models have shifted further east, that's a trend.
Member Since: August 19, 2005 Posts: 5 Comments: 5289
Quoting TampaSpin:


how can that be right ... on the left it says that wind speed is in mph but the winds at at 100 mph not 85 so is the winds really supposed to be in knots there?
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A good reminder this morning to not focus on a point but the cone of error. There are still portions of Florida that are in the 3 day cone as of 5am.
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587. HCW



Member Since: August 10, 2002 Posts: 0 Comments: 1408
Looks like a different HH plane is now trasmitting HDOB


000
URNT15 KNHC 231259
AF302 0809A IRENE HDOB 01 20110823
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http://www.ssd.noaa.gov/goes/east/carb/
flash-wv.html

Being in east central florida, I wont let my guard down until I see definite NW turn of storm and it passes my latitude. With that in mind, paranoia requires me to ask you to look at a feature to the NE of Irene. Can that make a change to what I hope is a recurve of Irene out to sea? BTW, the trough digging down pleases me because it looks like it will force Irene to miss everyone from a direct 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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