Irene - 8/25/2011 - (One of Two?) at 5:30 PM

Quick late afternoon update before I head home.

Irene has shown some signs of weakening today and it's no longer really expected that she'll attain category four status.  To that end, the overall guidance today has actually shifted back to the west, which shows a landfall south of the Outer Banks, an inland route until an exit back offshore north of Norfolk.  Irene would then track along the coast and make a second landfall in New Jersey/New York City(!) as a weak to moderate category two.

I don't buy it.

I totally get that Irene is weakening.  She was going to go under a decent amount of shear today and I think this little blip is primarily due to an eyewall replacement cycle that is periodic with hurricanes.  It could also be a sign of general weakening, and based on her position she may  not re-attain the strong category three status she once held.

If she does continue to stay a little weaker, I expect the track to go back a little bit further to the east.  This kind of track would call for initial landfall closer to OBX and Kill Devil Hills and a second landfall more likely between Eastern Long Island and Cape Code, with a third landfall possible somewhere between Maine and Canada.  Even if she does regain some of her strength back, I still expect a slight eastward jog than what the current forecast track is calling for, just not as pronounced.

Looking at overall model performance and verification, it looks like the GFS has been the most on-target, and it also appears as if the GFS is taking a more easterly course, so there is some support for this theory.  More models are a bit further west than this, but not but a whole lot.

If, and it's a very big if, New York is hit by Irene, the impacts could be severe.  The always excellent Jeff Masters has this to say.

NOAA's SLOSH model predicts that a mid-strength Category 2 hurricane with 100-mph winds could drive a 15 - 20 foot storm surge to Manhattan, Queens, Kings, and up the Hudson River. JFK airport could be swamped, southern Manhattan would flood north to Canal Street, and a surge traveling westwards down Long Island Sound might breach the sea walls that protect La Guardia Airport. Many of the power plants that supply the city with electricity might be knocked out, or their docks to supply them with fuel destroyed. The more likely case of a Category 1 hurricane hitting at high tide would still be plenty dangerous, with waters reaching 8 - 12 feet above ground level in Lower Manhattan. Given the spread in the models, I predict a 20% chance that New York City will experience a storm surge in excess of 8 feet that will over-top the flood walls in Manhattan and flood the subway system. This would most likely occur near 8 pm Sunday night, when high tide will occur and Irene should be near its point of closest approach. Such a storm surge could occur even if Irene weakens to a tropical storm on its closest approach to New York City.

I'll have more on this tonight after the game, but this could be one of the most severe storms to slam the east coast.  There's a chance it weakens enough (like Isabel in 2003) where the impacts are lessened significant than what was initially thought, but a hurricane hitting that far north in an area where people aren't used to it is a big deal.