TROPICAL STORM DEBBY DISCUSSION NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042006
1100 AM EDT WED AUG 23 2006
DEBBY APPEARS TO BE SLOWLY STRENGTHENING...BASED ON THIS MORNING'S
QUIKSCAT PASS THAT HAD A COUPLE OF BELIEVABLE 45 KT VECTOR. THE
SYSTEM ALSO SHOWED VERY GOOD ORGANIZATION ON AN 11Z MICROWAVE PASS.
CONVENTIONAL SATELLITE IMAGERY DOES NOT YET REFLECT THAT LEVEL OF
ORGANIZATION...AND DVORAK INTENSITY ESTIMATES RANGE FROM 35 TO 45
KT. THE SYSTEM IS MAINTAINING FAIRLY GOOD OUTFLOW UNDER LIGHT
EASTERLY SHEAR. THE THERMODYNAMIC ENVIRONMENT IS EXPECTED TO
SUPPORT ONLY SLOW DEVELOPMENT FOR THE NEXT COUPLE OF DAYS...BUT
DEBBY WILL BE MOVING BACK OVER WARMER WATERS AFTER THAT. GLOBAL
MODELS CONTINUE TO SUGGEST THAT AN UPPER LOW WILL CAUSE AN INCREASE
IN SOUTHERLY SHEAR LATE IN THE PERIOD THAT COULD SLOW THE
INTENSIFICATION. NEVERTHELESS...THE EXPLICIT INTENSITY GUIDANCE
CONTINUES TO INDICATE GRADUAL DEVELOPMENT TO NEAR HURRICANE
STRENGTH AND SO DOES THE OFFICIAL FORECAST.
THE INITIAL MOTION IS 300/15. DEBBY CONTINUES TO BE STEERED BETWEEN
WEST-NORTHWESTWARD AND NORTHWESTWARD AROUND THE SOUTHWESTERN
PERIPHERY OF A MID-TO UPPER-LEVEL HIGH CENTERED NEAR THE AZORES.
THERE HAS BEEN NO CHANGE TO THE BASIC SYNOPTIC THINKING. A
SIGNIFICANT WEAKNESS IN THE SUBTROPICAL RIDGE IS EXPECTED TO
DEVELOP AS A MID- TO UPPER-LEVEL TROUGH AMPLIFIES OVER THE CENTRAL
ATLANTIC LATE IN THE FORECAST PERIOD. ALL GUIDANCE MODELS EXCEPT
THE NOGAPS BEGIN A RECURVATURE BY DAY 5...AND THE NOGAPS DOES SO
SHORTLY THEREAFTER. THERE HAS BEEN VERY LITTLE CHANGE TO THE
OFFICIAL FORECAST TRACK AT THIS TIME...BUT I NOTE THAT MOST OF THE
GUIDANCE SHOWS A HARDER RIGHT TURN BY DAY 5 THAN THE OFFICIAL
FORECAST DOES.