5PM NOAA Discussion

ISAAC HAS MOVED A LITTLE TO THE LEFT OF PREVIOUS PROJECTIONS AND
CENTER FIXES YIELD A 6- TO 12-HOUR AVERAGED MOTION OF 295/15. THE
TRACK FORECAST CONTINUES TO BE CHALLENGING. THE DYNAMICAL MODELS
SHOW THE TROPICAL STORM/HURRICANE GRADUALLY TURNING TO THE RIGHT
AND HEADING FOR A BREAK IN THE SUBTROPICAL RIDGE. HOWEVER...THERE
ARE SUBSTANTIAL DIFFERENCES AMONG THE MOST RELIABLE MODELS AS TO
WHERE ISAAC MIGHT CROSS THE NORTHERN GULF COAST. THE U.K. MET.
OFFICE AND ECMWF MODELS ARE ABOUT 300 N MI TO THE EAST OF THE GFS
AT LANDFALL. IT SHOULD BE NOTED THAT NEARLY ALL OF THE GFS ENSMEBLE
MEMBERS ARE EAST OF THE GFS CONTROL TRACK. BECAUSE OF THE WIDE
MODEL SPREAD...THERE CONTINUES TO BE GREATER THAN USUAL TRACK
FORECAST UNCERTAINTY.

THROUGHOUT THE PERIOD...IT IS IMPORTANT NOT TO FOCUS ON THE EXACT
FORECAST TRACK DUE TO FORECAST UNCERTAINTIES AND THE FACT THAT
SIGNIFICANT HAZARDS EXTEND WELL AWAY FROM THE CENTER.