HOME	PRODUCTS	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDAT5 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM FLORENCE DISCUSSION NUMBER   4
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT MON SEP 11 2000
 
FLORENCE HAS BEEN MAKING A TIGHT CYCLONIC LOOP THE PAST 6 TO 12
HOURS AND THE CENTRAL DEEP CONVECTION HAS BEEN ON THE WANE THE PAST
5 HOURS.  EARLIER RECON REPORTS INDICATED FLORENCE WAS NEAR
HURRICANE INTENSITY...BUT THE INITIAL INTENSITY IS BEING HELD 
AT 60 KT DUE TO THE SHARP DECREASE IN THE CONVECTIVE PATTERN. 
OUTFLOW IS GOOD TO THE EAST...BUT RESTRICTED ELSEWHERE.

INITIAL MOTION IS QUASI-STATIONARY OR A SLOW DRIFT TO THE WEST OR
WEST-SOUTHWEST.  WITH THE RECENT DECREASE IN THE CENTRAL DEEP
CONVECTION...FLORENCE MAY BE STEERED BACK TO THE WEST BY THE
NORTHEASTERLY LOW-LEVEL ON THE SOUTH SIDE OF A LARGE HIGH PRESSURE
RIDGE LOCATED JUST OFF THE U.S. EAST COAST.  ALL OF THE GLOBAL AND
REGIONAL MODELS AGREE ON FLORENCE REMAINING IN A WEAK STEERING FLOW
REGIME FOR THE NEXT COUPLE OF DAYS...AND THEN GRADUALLY BEGIN TO
MOVE TO THE NORTHEAST OR EAST BY 72 HOURS AS A STRONG UPPER-LEVEL
TROUGH APPROACHES THE U.S. EAST COAST.  THE OFFICIAL FORECAST IS A
LITTLE TO THE EAST OF THE PREVIOUS FORECAST TRACK...AND SIMILAR TO
THE UKMET AND GFDL MODELS.

GIVEN THAT FLORENCE IS A RELATIVELY SMALL CIRCULATION...RAPID AND
SIGNIFICANT FLUCTUATIONS IN INTENSITY CAN OCCUR DUE TO VERTICAL
SHEAR AND DRY AIR INTRUSIONS.  SOME OF THE STRONG WINDS REPORTED BY
RECON AIRCRAFT EARLIER COULD HAVE BEEN ENHANCED BY STRONG DOWNDRAFTS
CREATED BY DRY MID-LEVEL AIR WRAPPING INTO THE CIRCULATION CENTER.
WATER VAPOR IMAGERY INDICATES THAT A GOOD DRY PUNCH HAS WRAPPED ALL
THE WAY AROUND INTO THE CENTER...WHICH HAS LIKELY HELP TO ERODE THE
CENTRAL CONVECTION.  SINCE THERE APPEARS TO BE AN ABUNDANCE OF DRY
AIR AROUND THE NORTHWEST HALF OF THE SYSTEM...ONLY SLOW
INTENSIFICATION IS FORECAST UNTIL A PERSISTENT STEADY TREND IN THE
CENTRAL DEEP CONVECTION OCCURS.
 
FORECASTER STEWART
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     12/0300Z 30.2N  72.8W    60 KTS
12HR VT     12/1200Z 30.1N  73.3W    60 KTS
24HR VT     13/0000Z 30.1N  73.9W    65 KTS
36HR VT     13/1200Z 30.6N  74.2W    70 KTS
48HR VT     14/0000Z 31.0N  73.5W    70 KTS
72HR VT     15/0000Z 31.5N  71.5W    60 KTS
 
NNNN