Fay-day Fay-day Fay-day

Tropical storm Fay, now sitting between Hispaniola and Cuba, appears an imminent threat to the U.S.  The severity and locality of this threat, however, is uncertain.

The 2 p.m. EDT advisory on Fay by the National Hurricane Center (NHC) projects a landfall on the southwest coast of Florida:
http://www.nhc.noaa.gov/nhc_storms.shtml

The various computer models used by the NHC produce a range of forecast tracks and storm intensities.  Generally, the track and intensity issued to the public is an average of these different forecasts.  One of the problems with tropical system forecasting is observational data.  Computer models need high-resolution observational data to produce good forecasts.  Often tropical systems sit over areas where these data are sparsely measured, or are measured remotely by satellite, so the forecasts can vary quite a bit from model to model.

With Fay there is a great deal of uncertainty.  As it passes over Cuba, its intensity and overall organization will decrease.  The extent of this decrease will determine its ability to re-strengthen once its center re-emerges in the Gulf of Mexico.  Atmospheric conditions are favorable for re-strengthening, so if slows a bit (already traveling a paltry 16 m.p.h.), it could strengthen more than projected before landfall.  Bad news.

Right now, the most likely scenario is for Fay to make landfall as a hurricane on the southwest coast of Florida, somewhere in the vicinity of the Cape Coral-Fort Myers area.  The intensity looks to be around 90 m.p.h. at landfall.  It is expected to accelerate after landfall, and may even still be a tropical storm when it reaches southern Georgia.  The main problem with Fay should be flooding.  But, that may not be completely bad news, as Georgia and the Carolinas are and have been in a drought:
http://drought.unl.edu/dm/monitor.html

This, like all important forecasts, may will change.