500 PM EDT MON JUL 21 2008
THE STRUCTURE OF DOLLY APPEARS TO BE UNDERGOING VERY GRADUAL
CHANGES. THE OUTERMOST CONVECTIVE BANDS HAVE BEEN WEAKENING
TODAY...WHILE CONVECTION HAS BEEN SLOWLY ON THE INCREASE NEAR THE
CIRCULATION CENTER. THE RADIUS OF MAXIMUM WINDS IS NOW MUCH
SMALLER...AS DETERMINED FROM STEPPED-FREQUENCY MICROWAVE RADIOMETER
DATA THAT RECENTLY INDICATED A MAXIMUM SURFACE WIND OF 45 KT ABOUT
45 N MI NORTHEAST OF THE CENTER. DOLLY IS HEADED TOWARD A RELATIVE
MAXIMUM IN OCEAN HEAT CONTENT...AND IT IS BENEATH A LARGE
UPPER-LEVEL ANTICYCLONE THAT COVERS NEARLY THE ENTIRE GULF OF
MEXICO. IT SEEMS TO BE TAKING A WHILE...HOWEVER...FOR AN INNER
CORE TO BEGIN TO TAKE SHAPE...SO IT IS RATHER UNCERTAIN HOW MUCH
DOLLY WILL TAKE ADVANTAGE OF ITS ENVIRONMENT. ALL OF THE INTENSITY
MODELS FORECAST AN UPWARD INTENSITY TREND UNTIL FINAL
LANDFALL...BUT THEY DO NOT AGREE ON THE AMOUNT OF STRENGTHENING.
THE SHIPS AND LGEM MODELS FORECAST ABOUT 65 KT IN 48 HOURS...WHILE
THE GFDL IS A LITTLE HIGHER AT 75-80 KT. SINCE THE ENVIRONMENT
APPEARS SO CONDUCIVE FOR STRENGTHENING...THE OFFICIAL FORECAST
AGAIN LEANS TOWARD THE HIGHER GFDL SOLUTION. ANOTHER COMPLICATION
IN THE INTENSITY FORECAST IS NOT KNOWING EXACTLY HOW FAST DOLLY
WILL REACH THE COAST. IF IT MAKES LANDFALL SOONER THAN THE
OFFICIAL TRACK INDICATES...IT MIGHT RUN OUT OF TIME TO REACH THE
OFFICIAL FORECAST PEAK INTENSITY. BUT IF THE OPPOSITE
OCCURS...DOLLY WOULD HAVE A LITTLE MORE TIME OVER THE WARM WATERS.
DOLLY CONTINUES TO MOVE QUICKLY...AND THE INITIAL MOTION ESTIMATE
REMAINS 300/16. WHILE IT IS A LITTLE UNNERVING TO OBSERVE THIS FAST
MOTION AND FORECAST THE CENTER OF DOLLY TO TAKE A COUPLE OF DAYS TO
REACH THE COAST...ALL OF THE DYNAMICAL MODELS INSIST THAT THE
FORWARD SPEED WILL BE ABOUT HALF ITS CURRENT VALUE BY TOMORROW
NIGHT. THE MODELS AGREE SURPRISINGLY WELL ON THE SLOW-DOWN...SO
THE OFFICIAL TRACK FORECAST...IN TERMS OF FORWARD SPEED...IS RIGHT
IN LINE WITH THE MODEL CONSENSUS. THE MODELS DO NOT GO INLAND IN
EXACTLY THE SAME LOCATIONS...HOWEVER. THE GFS AND UKMET FORECAST
DOLLY TO CROSS THE COAST OF NORTHEASTERN MEXICO...WHILE THE GFDL
AND HWRF TRACKS GO INTO SOUTHERN TEXAS. THE OFFICIAL TRACK
FORECAST IS A LITTLE NORTH OF THE CONSENSUS...GIVING RESPECT TO THE
AGREEMENT BETWEEN THE NWS HURRICANE MODELS...THE GFDL AND HWRF.
THIS NEW TRACK IS NOT MEANINGFULLY DIFFERENT THAN THE PREVIOUS
ONE...EXCEPT TO BE A LITTLE FASTER. IT IS AGAIN IMPORTANT TO
EMPHASIZE THAT...WITH RELIABLE MODELS ON BOTH SIDES OF THE OFFICIAL
TRACK...ONE SHOULD NOT FOCUS ON THE EXACT LANDFALL LOCATION IMPLIED
BY THE OFFICIAL TRACK.
WARNINGS WILL LIKELY BE REQUIRED FOR PORTIONS OF THE HURRICANE AND
TROPICAL STORM WATCH AREAS LATER TONIGHT.
No comments:
Post a Comment