Category 2 Irene Approaches The Bahamas
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
Reader Comments
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This is really good news!!!
We will see.
Those of us in ENC disagree..
Good news.
Indeed, Irene has been trending right since she began. Hopefully the trend continues, nobody needs a CAT4. Trends can change however, this is just the flavor of the morning :-)
This forum is a very bad place to get information to make decisions on preparation or evacuations (you are correct in waiting to hear from HPC)
With that said, this is a forum to talk weather (and spray so it seems) The current model situation is like almost all others in that the models can do whatever they want (they are bound by the laws of physics) but the current observations are, and that’s what counts. They are pointing to a different picture of a track. There is no way Irene is going to make landfall if the next 2 upper level disturbances are as strong of the one from this weekend over the northern US. (and short term historic observations point to a decent probability of that happening)
Looks like we aren't going to get anything at all from that HH plane. Has to be said, there's been several occasions this year when recon planes have had problems.
Any evidence that proves it would be nice.
Those models on the right aren't exactly great (BAMS, AEMN, etc.)
The consensus still very much favors direct impacts unfortunately.
NEXT UP........:(
Hey Grandpa, I'm not totally sure that Raleigh is a safe bet. I'm in Wilmington and may go to Charlotte.
What do you guys think the effect of the gulfstream will have? My very newbie weather watcher mind says major strengthening.
Looks like they went home.
Irene is still very likely to bring some significant impacts to the coast even if it stays offshore.
These are the BAM MODELS.........WOW they have been RIGHT on with IRENE........unreal how well they have performed based on intensity...gotta say the GFS has been all over it also.
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----
This is every MODEL known to man......LOOKING BETTER for a non ConUs direct hit!
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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URNT15 KNHC 231259
AF302 0809A IRENE HDOB 01 20110823
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?
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.
First one went home. Must have had mechanical problems. These aircraft seem far from reliable.
Excellent advice!
That is the forecast Windspeed for the next landfall hit....
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.
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