Tropical Storm FLORENCE

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TROPICAL STORM FLORENCE DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062012
500 PM AST SAT AUG 04 2012
 
AFTER LOOKING A LITTLE RAGGED EARLIER...CONVECTION HAS REDEVELOPED
NEAR THE CENTER OF FLORENCE...WHICH APPEARS TO BE THE START OF A
CENTRAL DENSE OVERCASE PATTERN.  SUBJECTIVE SATELLITE INTENSITY
ESTIMATES WERE 35 KT AND 45 KT FROM SAB AND TAFB RESPECTIVELY. 
SINCE A TRMM MICROWAVE PASS FROM EARLIER TODAY SUGGESTED THAT SOME
PRIMITIVE INNER CORE FEATURES HAD FORMED...AND BOTH AMSU AND ADT
DATA INDICATE A STRONGER CYCLONE...THE INITIAL INTENSITY WILL BE
BUMPED UP TO 45 KT.  

THE CURRENT SYMMETRIC OUTFLOW PATTERN WITH FLORENCE APPEARS
FAVORABLE FOR FURTHER INTENSIFICATION.  HOWEVER...THE SYSTEM IS
PASSING OVER WATERS COOLER THAN 26.5C...AND IS APPROACHING A MORE
STABLE AND DRY ENVIRONMENT AS INDICATED BY EUMETSAT RGB AIRMASS
IMAGERY.  THE INTENSITY GUIDANCE HAS A WIDE RANGE OF POSSIBILITIES. 
THE STATISTICAL-BASED TOOLS FORECAST FLORENCE TO BE NEAR OR ABOVE
HURRICANE STRENGTH IN A DAY OR TWO...WHICH IS CONTRASTED WITH THE
WEAKENING FORECAST BY THE HWRF/GFDL MODELS.  THE OFFICIAL FORECAST
IS JUST A BIT ABOVE THE INTENSITY CONSENSUS AND IS HIGHER THAN THE
PREVIOUS ONE.  GIVEN THE EARLIER MICROWAVE STRUCTURE...IT IS
TEMPTING TO RAISE THE WIND PREDICTION MORE THAN WHAT IS INDICATED
BELOW...BUT I HAVE ELECTED TO REMAIN CONSERVATIVE ON THIS FORECAST
CONSIDERING THE MARGINAL ENVIRONMENT.  
 
THE INITIAL MOTION ESTIMATE IS A LITTLE SLOWER...295/13.  A BUILDING
MID-TROPOSPHERIC HIGH OVER THE EASTERN ATLANTIC OCEAN IS EXPECTED
TO CAUSE FLORENCE TO BEND TO A WESTWARD HEADING DURING THE NEXT DAY
OR TWO.  HOWEVER...THE GLOBAL MODELS HAVE A WIDER SPREAD THAN
EARLIER TODAY...WITH THE ECMWF AND GFS SHOWING LITTLE RUN-TO-RUN
CONSISTENCY.  GENERALLY THE MODELS THAT ARE FORECASTING A MORE
POWERFUL SYSTEM...SUCH AS THE GFS...ARE CAUSING FLORENCE TO TURN
NORTHWESTWARD AROUND DAY 4 IN RESPONSE TO A WEAKNESS IN THE RIDGE. 
A WEAKER CYCLONE...AS INDICATED BY THE ECMWF...WOULD PROBABLY JUST
CONTINUE MOVING WESTWARD.  SINCE THE LATEST INTENSITY FORECAST IS
BETWEEN THESE TWO EXTREMES...THE LATEST NHC FORECAST IS CLOSE TO
THE MODEL CONSENSUS...JUST A BIT NORTH OF THE PREVIOUS FORECAST IN
THE LONG RANGE PERIOD.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  04/2100Z 15.3N  31.7W   45 KT  50 MPH
 12H  05/0600Z 15.8N  33.4W   50 KT  60 MPH
 24H  05/1800Z 16.2N  35.7W   50 KT  60 MPH
 36H  06/0600Z 16.6N  38.1W   45 KT  50 MPH
 48H  06/1800Z 17.1N  41.2W   45 KT  50 MPH
 72H  07/1800Z 18.5N  47.8W   40 KT  45 MPH
 96H  08/1800Z 20.5N  54.0W   35 KT  40 MPH
120H  09/1800Z 23.0N  59.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER BLAKE
 
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