Irma’s Projected Path Shifts West; Storm Expected to Restrengthen to Category 5

As of the 5 PM advisory from the National Hurricane Center (NHC), dangerous Hurricane Irma was packing 155 mph maximum sustained winds and tracking just north of due west off the Cuba coast.

The new advisory provides a couple of surprises. One, Irma’s path has shifted more to the west. As a result, the West Coast of Florida and western South Florida is under more of a threat from Irma. That said, the NHC has not backed off its storm surge forecast of 5-10 feet for places like Miami. So, so far, that vulnerable city is not out of the woods — particularly for southern sections of the city.

(Official track shifts west for Irma as the Hurricane Center now predicts the storm will restrengthen to category 5 intensity over the Florida Straits after raking the coast of Cuba. Image source: The National Hurricane Center.)

This is likely due to the fact that Irma has a very large circulation with tropical storm force winds extending outward up to 160 miles from its center and hurricane force winds extending up to 60 miles from the storm’s center. So a west coast landfall in South Florida has the potential to still bring hurricane conditions to places like Miami. That said, if the track continues to shift west, Miami may dodge a bullet as our concerns shift to places like Fort Myers and possibly Tampa.

The NHC’s full statement on present storm surge potential is as follows:

SW Florida from Captiva to Cape Sable…8 to 12 ft
Cape Sable to Boca Raton including the Florida Key…5 to 10 ft
Venice to Captiva…5 to 8 ft
Anclote River to Venice including Tampa Bay…3 to 5 ft
Boca Raton to Flagler/Volusia County line…3 to 6 ft

So basically all of South Florida from Cape Coral to Boca Raton is looking at a 5-12 foot storm surge according to the present NHC forecast. That includes Miami, Ft Lauderdale, the Keys, and the Fort Myers area.

(The NHC’s 5 PM storm surge inundation map shows the potential for significant flooding from South Miami to the Cape Coral area and on out to the Florida Keys. For reference, blue regions are expected to see more than one foot of water above ground, yellow more than three feet, orange more than six feet, and red more than nine feet.)

The second surprise in the recent official forecast is that the NHC now briefly expects Irma to regain category 5 status as it crosses the Florida Straits. Projected 36 hour intensity from NHC is for a storm packing 160 mph winds at that time. This increase in strength now jibes with a number of model forecasts that show Irma tapping much warmer than normal Gulf Stream waters just prior to striking Florida.

It’s worth noting that intensity forecasts are sometimes tough to nail down and the NHC is quick to caution that fluctuations in storm strength are likely. In any case, this is a very dangerous storm that bears watching.

(UPDATES TO FOLLOW)

 

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