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
