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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Hard to say really.
Good point there. Goes hand in hand with the slower motion of the storm.
69Viking
Quoting Abacosurf:
That confirms the wobble to the WSW.
How does a storm go from 20.6N to 20.5N and the NHC in their advisory still says it's moving WNW??? Even if it's a wobble the movement from one advisory to the next was to the WSW, why lie about that? I'm goint to laugh if Irena misses the next trough, then who knows where she would end up. Not to mention that "thing" off the coast of Georgia, yep, this is getting to be a fun one to track!
yes it does!!
Thought so too.. I liked the thing with the bowl... pretty good.
I can understand the wobble and the dry air in the center....
But how come the other stuff wasn't picked up like the blob and the trough speed?
not if hispanolia weakens her a bit...could cause a slight shift back to the west...sorry...
It is not over until it dissipates!
Exactly fits my description to a tee.
http://www.nhc.noaa.gov/surge/
I have seen the difference personally.
Why am I replying to a troll??
Have you never seen a tropical cyclone stay in the Atlantic with no land interaction? I've seen plenty of them. I call them FISH storms as do most other's here.
I live in CHS and I'm still a bit nervous...
uhm did you see the latest fix? clearly you did not..if so you would agree wobble wobble. I just call it like i see it...don't get mad.
Sorry, "picked up" by what?
Agree.
Isn't that what happend to Jeanne, and what caused her to do the loop d loop.
Posted that awhile back , looks like some just can't handle the truth, not sayin it won't go where the NHC has forecasted it to, but why not be truthful about the direction, simple as that!
That is what I am looking at. Wow the weather is unpredictable. Where was this blob yesterday lol?
You never know... LOL!
It's ridiculous as hell but you can't turn away because it's hilarious!
Click image for enlarged view
Will be interesting to see what the NHC does with this new data showing significant weakening and deterioration of the inner structure of the hurricane in the next update.
The AB high has once again nosed W slightly as well as changing orientation a bit. The trough appears to be trying to flatten as well. Texas ridge is roughly the same. No major changes but:
Link
They plot their track as a consensus of model track and model track changes as the conditions change; what were your thoughts on how they did it? Should they stick to a track despite the fact that it's wrong? Or do you have a way of making a storm conform to a specific track?
I think the most likely outcome is that Irene attempts to absorb the low pressure blob. This could do anything to the track, it's very difficult to forecast.
You, sir, obviously DIDN'T live thru JEANNE!
im in Chas too...and will not start feeling better untill she is due east of me and still trucking... worried that hispanolia is gonna cause more shifts...and not only that...this thing is pretty big...even if she ran the coast and was 60 miles out we would still get some vicious storms for a while
The 7 PM track might have SC under the gun.
It's the result of a pretty big thunderstorm complex that came off shore last night, but looks like it might have detached from the front.
I think they'll be reluctant to lower the wind speed, as it may make people complacent when in reality Irene could still strengthen a lot when it gets away from Hispaniola.
maybe NHC just for got to put the S between the W's,since it's been wnw from the getgo pretty much
Seems quite reasonable. Would not surprise me to see further weakening throughout the day as the current storm motion as shown by the last few Hurricane Hunter fixes shows the storm closer to Hispanola and moving slower.
FLORIDIANS OF THE BLOG! Give it a damn rest. It's over. There is no West movement, no matter how much you pray to your raingods. Get over the denial already, its tiresome. Your like that team behind by 10 runs in the 9th inning with 2 outs and still thinking you have a shot.
I for take offense to the sports analogy. the storm may be over for Florida but never quit in sports.
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