Thursday, August 25, 2011

Irene Continues to Pound the Bahamas; Watches Issued for Carolinas

Above is the latest visible satellite image of Irene, and the corresponding infrared image is below. As of the 8am EDT National Hurricane Center (NHC) advisory, the center of Hurricane Irene was located about 65 miles East/Northeast of Nassau, Bahamas, and moving Northwest at 13 mph.

Maximum sustained winds were 115 mph, and the minimum central pressure was 28.05 inches of mercury (950 millibars.

The NHC has issued a Tropical Storm Watch for the South Carolina coast from North of Edisto Beach to Surf City, North Carolina.  A Hurricane Watch has been issued for the North Carolina coast from Surf City to the North Carolina/Virginia border.  This includes the Pamlico, Albemarle and Currituck Sounds.

We've been advising folks in this area to make preparations for 4 days now.  The fact that an "official" watch has now been issued will hopefully spur those to action who have not done so thus far.

Observations of Irene from Air Force Hurricane Hunter aircraft, satellite imagery and surface observations, along with the overnight runs of the computer forecast models have not resulted in a significant change in my thinking on the track of Irene since yesterday evening's post.  Please see that post for additional details.  The official NHC forecast track through the Carolina's also remains largely unchanged this morning, and that latest image is shown below:

As I pointed out in the above referenced post yesterday evening, I would like to remind folks in North Carolina not to fixate on the forecast track of the center of Irene (as indicated by the black dots on the above image).  That is the forecast location of the center only.  The hurricane force wind field around the center of Irene (including the Western side) is already quite large and is forecast to grow even larger today.  Even if the center of Irene tracks over or just East of the Outer Banks, 80+ mph winds would still take place as far West as I-95 in North Carolina based on the current size of that wind field.  This threat could even spread further West if the wind field continues to expand at its present pace.

A key element involved in the forecast track and intensity of Irene will come into play later tonight.  Irene is currently forecast (for several days now) to make a turn more toward the North in response to a change she'll encounter in the overall middle and upper level wind flow pattern.  This turn is forecast to take place after the center passes about 150 or so miles due East of Cape Canaveral Florida early tonight.  Whether or not that turn takes place as currently expected will have a significant impact on the forecast path of Irene in the near term, as well as better defining the potential impacts on the Carolinas - and beyond.  Right now I am not seeing any data (actual observations or computer forecast models) that gives me any reason to doubt that the turn will take place as expected.

I plan to make some individual posts later today regarding the likely impacts on specific geographic areas.  It goes without saying that if you live from North Carolina on Northward into New England, you should have your preparedness plans well under way at this time.  Irene is a very dangerous storm, and is likely to have a very significant impact on these areas.

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