Sunday, August 21, 2011

Irene Organizing in Caribbean - Threat to Florida by Friday, Eastern U.S. Beyond

The above satellite image shows the center of Tropical Storm Irene swirling about over the Caribbean. At 8am EDT, the center of Irene was located about 35 miles West/Northwest of Guadalupe, and moving toward the West at a rather brisk 21 mph  Maximum sustained winds were 50 mph, and the minimum central pressure was 29.68 inches of mercury.

You can also clearly see the center of Irene (noted by the red arrow) on this recent image from the French Government's radar site at Guadalupe:

Irene is currently forecast to maintain a general West to West/Northwestward motion for the next couple of days, before turning more toward the Northwest by mid-week.  The "official" National Hurricane Center (NHC) forecast is below:

Based on the present forecast track, the center of Irene will pass immediately South of Puerto Rico during the early morning hours on Monday.  Irene is then forecast to reach hurricane strength by the time she approaches the Dominican Republic later in the day on Monday.

Here in the U.S., of course, the concern is what track she will take beyond that point.  As I pointed out a few paragraphs above, computer forecast models continue to show Irene turning more toward the Northwest as she approaches Cuba by mid-week.  A composite image of the latest computer forecast model guidance is shown below:

As you can see, the official NHC forecast track lies right down the middle of the computer guidance at this time.  Both the majority of the computer models and the official NHC forecast currently indicate significant impact on Florida with the center tracking along the Southern or Eastern coast during the pre-dawn hours of Friday morning.  The exact timing of the expected Northwestward turn of Irene late Tuesday or early Wednesday will hold a major key to pinpointing the locations of greatest impact in Florida.

The major key to forecasting the intensity of Irene when she reaches Florida will be how much land mass the center of the storm will pass over as she crosses the rugged terrain of the Dominican Republic, Haiti and eastern Cuba early this week.  Forecast models and the official forecast both show weakening due to this, however it is likely that Irene will rapidly develop back to hurricane strength once she emerges out over the very warm waters between the Florida Straights and Cuba on Thursday.

From now through at least the impact on Florida, the forecast track of Irene is taking on a striking similarity to that of Hurricane Cleo back in 1964:

In fact, if we take a look at the latest GFS computer model forecast for the end of this week, you'll see just how close the projected path of Irene corresponds to the actual path of Cleo from 1964.  The first GFS image is valid 8am EDT Friday, 8-26-11 (Irene is the "blob" over Florida in the lower left quadrant of the image):

The next is valid at 8am EDT Saturday, 8-27-11:

and finally, 8am EDT Sunday, 8-28-11:

Looking even further out into the future prospects of Irene, the GFS model from next Sunday forward continues to track the system along the Eastern seaboard into southern New England, as shown on the series of images below, first being valid 2pm EDT Monday, 8-29-11:

...and 2pm Tuesday, 8-30-11:

This "coast hugging" track that is forecast by the GFS model from South Carolina on Northward along the Eastern seaboard is in close proximity to the actual track of Hurricane Charley from 2004 (though a little further Westward on the Northern end):

Beyond the Florida impacts on Friday, this is all of very speculative of course, however the overall middle and upper-level weather pattern does support a Cleo-Charley "hybrid" like track as depicted by the GFS forecast model images above.  If this indeed comes to pass, it is possible that we'll have significant impacts from Irene not only in Florida by the end of this week, but Northward along much of the Eastern seaboard through the early part of the following week.

Residents of Florida should begin making a plan of action for later this week now.  Stock up on needed supplies and review Hurricane Preparedness Tips early so that you don't have to rush around and potentially panic as the event draws near.

Residents all along the Southeast U.S. coast, and even Northward along the Eastern seaboard, should keep a close eye on the forecast track of Irene this week and be prepared to take action as the future path of the system becomes more definite.

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