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Fay slowly intensifying, but not expected to be another Hurricane Charley

By: Dr. Jeff Masters, 3:22 PM GMT on August 17, 2008

Tropical Storm Fay is slowly growing better organized as it tracks south of Cuba, over the warmest waters of the Atlantic Ocean. Radar imagery from Pico San Juan, Cuba shows that the low-level spiral bands are not yet well-organized. Visible satellite loops show that Fay has only a small amount of heavy thunderstorm activity near its center. Fay is in a slightly less favorable wind shear environment, with upper-level winds from the west creating 10 knots of wind shear. Upper level outflow is well-established only to the north and east, and Fay does not look very impressive at this time.

Yesterday Fay claimed its first victims, when four people died in flooding on the Dominican Republic and Haiti. Satellite rainfall estimates suggest at least six inches of rain have fallen over portions of Hispaniola, with lesser amounts over Cuba and Jamaica. As Fay continues to organize today, heavy rain will increasingly affect Cuba, Jamaica, and the Cayman Islands, potentially causing serious flooding.

The forecast for Fay
It's unusual for the computer models to be so divergent just 48 hours before expected landfall in the U.S. "The Joker" seems intent on keeping us guessing until the last day, and we really don't know where this storm is going to go. One heartening development: none of the three major intensity forecast models (GFDL, HWRF, and SHIPS) foresee Fay getting stronger than a Category 1 hurricane. This is in contrast to some of their runs late last week, which had Fay intensifying into a major hurricane. The new model runs are foreseeing a less favorable upper-level wind regime when Fay gets north of Cuba, with increased levels of wind shear on the northern side of the storm.

The latest (2 am EDT) model runs of the GFDL and GFS models are similar to each other, taking Fay to a landfall in Southwest Florida near Ft. Myers Monday night, then across Florida and northwards towards South Carolina. The GFDL predicts Fay will hit South Carolina as a Category 1 hurricane with 75 mph winds and a 981 mb pressure on Wednesday afternoon. The latest (8 pm EDT) run of the ECMWF model is similar.

In contrast, the latest (2 am EDT) run of the HWRF model takes Fay straight north into Tampa Tuesday morning, as a strong Category 1 storm with 90 mph winds and a 961 mb pressure. The latest UKMET model run is similar. The NOGAPS model continues to insist on a landfall near the Alabama coast on Wednesday, despite the sea turtle forecast I mentioned in yesterday's blog.

Figure 1. Track of Hurricane Charley, which struck Cuba as a Category 3 hurricane with 120 mph, then Southwest Florida as a Category 4 hurricane with 145 mph winds.

Comparing Fay to Hurricane Charley
Residents of Southwest Florida are nervously watching Fay as it approaches Cuba, recalling an August day four years ago when Hurricane Charley crossed Cuba at a similar location. Charley went on to become one of the most destructive hurricanes in history, wreaking $15 billion in damage after roaring ashore near Punta Gorda, Florida, as a Category 4 hurricane with 145 mph winds. Charley put on a remarkable and unexpected burst of rapid intensification just before landfall. Could the same thing happen with Fay? After all, the sea surface temperatures, total ocean heat content, and wind shear are similar for the two storms. And, Fay has consistently lived up to its knickname of "The Joker", with its unpredictable behavior.

Well, Fay is no Charley. By the time Charley crossed Cuba, it was already a well-developed Category 3 hurricane with 120 mph winds. Fay will be lucky to be a minimal Category 1 hurricane with 75 mph winds when it crosses Cuba. Charley's crossing of Cuba knocked its winds down by 10 mph, and we can expect a similar or greater loss of strength when Fay crosses Cuba, since it is a less organized storm than Charley was. This would make Fay a tropical storm with 65 mph winds as it moves past Key West towards Southwest Florida. It's a pretty tall order to ask a tropical storm that has not yet developed an organized eyewall to put on a major intensification burst to major hurricane status in just one day. Southwest Florida is not going to see a repeat of the Hurricane Charley experience. I give Fay just a 10% chance of making Category 3 status, and that would most likely occur if it avoids a Southwest Florida landfall, and is able to spend an extra day over water and hit the Florida Panhandle or middle Gulf Coast near Alabama. There is also a 10% chance Fay could make major hurricane status if it crosses Florida and re-organizes south of South Carolina later this week.

Links to follow
Wundermap for Cuba
Pico San Juan, Cuba radar
Key West, FL weather

Elsewhere in the tropics
Several of the reliable computer models are predicting development of a tropical wave currently located off the coast of Africa, just south of the Cape Verde Islands. This system is expected to track west-northwest and be near or just north of the Northern Lesser Antilles Islands about a week from now.

I'll have an update today by 4:30 pm EDT, when the latest set of model runs and new Hurricane Hunter data will be available.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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