Tuesday, August 23, 2011

Irene Hammering Bahamas; Major Eastern U.S. Impacts Still on Track

The above visible satellite image of Hurricane Irene was taken a short time ago. As of the 5pm EDT National Hurricane Center (NHC) advisory, the center of Irene was located about 50 miles South/Southwest of Grand Turk Island.  This is also about 110 miles East of Great Inagua Island.  Maximum sustained winds were 90 mph, with a minimum central pressure of 28.82 inches of mercuty.

As you can see by the 90 mph wind measurement, Irene has weakened very slightly since the last observation, however this will prove to be a short lived trend.  Further intensification is likely, and I still expect Irene to affect the U.S. East Coast as a major hurricane in a few days time.

The visible satellite image below was taken at about 1:45 PM EDT, and you could see the eye of Irene at that time (it has since become obscured by high cloudiness once again):

Irene continues moving toward the West/Northwest, though she has slown down a bit during the day today, currently moving at 9 mph.

Computer forecast models still call for Irene to turn more toward the Northwest during the day on Wednesday, as shown on the latest composite image below:

The official NHC forecast track is basically down the center or slightly to the left of the model consensus, and calls for the center to pass very near the outer banks of North Carolina during the day Saturday:

Irene is likely to be a major hurricane as the center passes East of Florida on Thursday and Friday, and makes landfall in eastern North Carolina (or perhaps the outer banks) on Saturday.  It is important to remember that both tropical Storm and Hurricane force winds will extend well out from the center of Irene by the time she approaches the U.S. Coast.  When you look at the track/forecast maps, the "dot" on the map represents only the center of the system.  Irene is forecast to become an even larger hurricane (in areal extent), so her impacts will spread out accordingly.  With that in mind, even though the center of Irene is forecast to track East of Florida, it is likely that at least Tropical Storm force winds will affect Eastern portions of the state on Thursday night into Friday.  We'll be able to pinpoint this more on Wednesday as we see how the wind field expands on the Western side of Irene.

If Irene makes the expected Northward turn on Thursday afternoon (to the East of Miami), the center will likely make landfall somewhere in far eastern North Carolina (or perhaps the outer banks) on Saturday afternoon.  Computer models are currently forecasting sustained winds of as "little" as 115 mph to as much as 140 mph across this region on Saturday afternoon.  The GFS model forecast (one of the more conservative at 115 mph sustained winds), is shown below:

Needless to say, if you live in the Carolinas, particularly the Eastern portions of that region, you should continue to prepare for a major hurricane impact on Saturday.  Review safety and preparedness tips, stock up on needed supplies before they are diminished, and have a full fledged evacuation plan in mind as well.

As I've been saying here for several days now, the impacts of Irene will be felt much further North from the original point of landfall.  In fact, it is looking increasingly likely that Irene will impact a large portion of the Eastern seaboard over the weekend and into early next week, including the "big cities" in the Northeast and New England.

The ECMWF computer forecast model is currently calling for the center of Irene to pass over or just East of Chesapeake Bay (to the immediate East of the Baltimore/Washington area) on Sunday morning, with maximum sustained winds of up to 115 mph (on the Western side, stronger over coastal waters):

The GFS computer forecast model is calling for a similar position on Sunday morning, but with maximum sustained winds of around 90 mph (again, on the Western side, stronger over the coastal waters):

Regardless of which model verifies intensity-wise, the potential impact on the Northeast corridor from Washington through New York City is obvious (if not quite scary).

Thankfully we have some time to monitor the progress of Irene this week as she approaches this region, however I strongly suggest that residents of the "big cities" in the Northeast corridor, as well as up into the Boston area, make plans for a possible major hurricane impact over the weekend.  More specific details will be available in the coming days, however I advise residents of this region to prepare now before a potential "panic" sets in later in the week.

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