Tropical Storm IDA Forecast Discussion

000
WTNT41 KNHC 092056
TCDAT1
TROPICAL STORM IDA DISCUSSION NUMBER  24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112009
300 PM CST MON NOV 09 2009

WITH ONE INTERESTING EXCEPTION...THE LATEST REPORTS FROM AN AIR
FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT INDICATE THAT IDA
REMAINS JUST BELOW HURRICANE STRENGTH. A CONVECTIVE BURST THAT
BEGAN A FEW HOURS AGO HAS TEMPORARILY HALTED THE WEAKENING TREND.
PEAK 850 MB FLIGHT-LEVEL WINDS OF 75 KT AND PEAK SFMR WINDS OF 58
KT SUPPORT MAINTAINING THE ADVISORY INTENSITY AT 60 KT. ON THE MOST
RECENT OUTBOUND PASS...HOWEVER...THE SFMR DID REPORT A VERY SMALL
AREA OF 70-75 KT SURFACE WINDS SOUTHWEST OF THE CENTER JUST
DOWNWIND OF THE CONVECTIVE BURST. GIVEN THAT THE CONCURRENT
FLIGHT-LEVEL WINDS WERE ONLY 45 TO 55 KT...THIS APPEARS TO BE A
LOCAL CONVECTIVE-SCALE PEAK UNREPRESENTATIVE OF THE CIRCULATION.

SSTS BELOW THE CENTER ARE NOW ABOUT 26C...AND GET PROGRESSIVELY
COOLER ALONG THE PROJECTED TRACK. VERTICAL WIND SHEAR WILL ALSO BE
INCREASING OVER THE NEXT 12 HOURS OR SO. THE 12Z GLOBAL MODELS
STILL DO NOT SHOW MUCH IN THE WAY OF BAROCLINIC RE-INTENSIFICATION
PRIOR TO LANDFALL...AND SO A RESUMPTION OF THE EARLIER WEAKENING
TREND IS EXPECTED TO COMMENCE SOON.

IDA IS NOW MOVING NORTHWARD...355/16. THE DYNAMICAL GUIDANCE
INDICATES THAT THE FORWARD MOTION SHOULD SLOW APPRECIABLY OVER THE
NEXT 12 HOURS...BUT IF THE CONVECTION PERSISTS MUCH LONGER IDA WILL
LIKELY MOVE ON SHORE SOONER THAN FORECAST. MY OFFICIAL 12 HOUR
FORECAST POINT IS ALREADY AHEAD OF MOST OF THE GUIDANCE. THE
REMAINDER OF THE FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY
TRACK...AND CALLS FOR IDA TO TURN EASTWARD AFTER LANDFALL AS IT
BECOMES EMBEDDED WITHIN A MID-LATITUDE TROUGH MOVING EASTWARD FROM
THE WESTERN GULF.

STRONG WINDS COVER A LARGE AREA OF THE GULF OF MEXICO AND RAINBANDS
ARE ALREADY MOVING ONSHORE WELL AHEAD OF THE CENTER.  GIVEN THE
CURRENT MOTION AND CONVECTIVE VIGOR...IDA SHOULD MAINTAIN TROPICAL
CHARACTERISTICS THROUGH LANDFALL. 


FORECAST POSITIONS AND MAX WINDS

INITIAL      09/2100Z 28.4N  88.5W    60 KT
 12HR VT     10/0600Z 30.2N  88.1W    50 KT
 24HR VT     10/1800Z 31.0N  87.1W    40 KT...INLAND
 36HR VT     11/0600Z 31.0N  85.5W    30 KT...EXTRATROPICAL
 48HR VT     11/1800Z 30.0N  83.5W    25 KT...EXTRATROPICAL
 72HR VT     12/1800Z...DISSIPATED

$$
FORECASTER FRANKLIN