T.S. Isaac Discussion #23

000
WTNT44 KNHC 262102
TCDAT4

TROPICAL STORM ISAAC DISCUSSION NUMBER  23
NWS NATIONAL HURRICANE CENTER MIAMI FL  AL092012
500 PM EDT SUN AUG 26 2012

ALTHOUGH SATELLITE AND RADAR IMAGES 
HAVE SUGGESTED THAT THE TROPICAL
CYCLONE WAS BECOMING A LITTLE BETTER 
ORGANIZED...AN AIR FORCE HURRICANE 
HUNTER AIRCRAFT INVESTIGATING ISAAC 
THIS AFTERNOON HAVE FOUND THAT THERE 
HAS BEEN NO STRENGTHENING OF THE STORM. 
FLIGHT-LEVEL AND SFMR-OBSERVED WINDS 
SUPPORT AN INTENSITY OF 50 KT. THERE IS 
STILL A WELL-ESTABLISHED UPPER-LEVEL 
OUTFLOW PATTERN OVER THE SYSTEM...
AND VERTICAL SHEAR SHOULD REMAIN 
FAIRLY LIGHT FOR THE NEXT COUPLE OF 
DAYS.  INTENSIFICATION STILL SEEMS LIKELY
AS ISAAC MOVES OVER THE EASTERN GULF...
AND  POSSIBLY OVER THE HIGHER HEAT
CONTENT OF THE LOOP CURRENT.  THE 
OFFICIAL INTENSITY FOREAST IS CLOSE TO 
THE LATEST LGEM GUIDANCE...AND NOT 
MUCH DIFFERENT FROM THE PREVIOUS 
NHC FORECAST.    

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.

THE OFFICIAL FORECAST TRACK AND 
WIND RADII NECESSITATE THE ISSUANCE
OF A HURRICANE WARNING FOR THE 
NORTHERN GULF COAST AT THIS TIME. 

FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 24.2N  82.3W   50 KT  60 MPH
 12H  27/0600Z 25.1N  83.9W   55 KT  65 MPH
 24H  27/1800Z 26.3N  85.9W   60 KT  70 MPH
 36H  28/0600Z 27.7N  87.6W   70 KT  80 MPH
 48H  28/1800Z 28.9N  88.5W   80 KT  90 MPH
 72H  29/1800Z 30.7N  89.5W   85 KT 100 MPH...INLAND
 96H  30/1800Z 32.5N  90.0W   30 KT  35 MPH...INLAND
120H  31/1800Z 34.5N  90.0W   20 KT  25 MPH...INLAND

$$
FORECASTER PASCH