[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 051439
TCDAT1

TROPICAL STORM FLORENCE DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062012
1100 AM AST SUN AUG 05 2012

VISIBLE IMAGES SUGGEST THAT SOUTHEASTERLY SHEAR HAS TAKEN A TOLL ON
THE STRUCTURE OF FLORENCE.  THE CENTER APPEARS TO BE ON THE EDGE OF
A WEAKENING AREA OF CONVECTION...WITH SOME DEGRADATION NOTED ON
MICROWAVE IMAGES.  A BLEND OF THE MOST RECENT ESTIMATES STILL GIVES
A CURRENT WIND SPEED OF 50 KT...BUT THIS COULD BE GENEROUS.  THERE
HAS BEEN A CHANGE WITH THE INTENSITY GUIDANCE...WITH NONE OF THE
MODELS SHOWING ANY SIGNIFICANT STRENGTHENING.  PERHAPS THIS IS
BECAUSE OF A SLIGHTLY DRIER AND MORE SHEARED ENVIRONMENT THAN WAS
EXPECTED YESTERDAY.  IN ANY EVENT...GLOBAL MODELS SHOW FLORENCE
MOVING DEEPER INTO THE DRY AIR FOR THE NEXT SEVERAL DAYS.  ALTHOUGH
SSTS SHOULD GRADUALLY BE RISING...STRONGER SHEAR IS LIKELY WITHIN
48 HOURS DUE TO A LARGE MID-OCEANIC TROUGH.  THESE CONDITIONS
SHOULD GENERALLY CAUSE WEAKENING OF THE CYCLONE...AND THE OFFICIAL
FORECAST IS REDUCED FROM THE PREVIOUS ONE.  THE NHC PREDICTION IS
PRIMARILY BASED ON A BLEND OF THE PREVIOUS FORECAST AND THE
INTENSITY CONSENSUS.  I WOULD NOT BE SURPRISED IF THIS SYSTEM
BECAME A REMNANT LOW FASTER THAN WHAT WAS INDICATED BELOW GIVEN THE
MARGINAL CONDITIONS.

MICROWAVE AND CONVENTIONAL IMAGES SHOW THAT FLORENCE HAS TURNED
WESTWARD AT ABOUT 12 KT AS PREVIOUSLY FORECAST.  A FASTER WESTWARD
MOTION OF THE CYCLONE IS EXPECTED FOR THE NEXT COUPLE OF DAYS WHILE
A RIDGE BUILDS OVER THE EAST-CENTRAL ATLANTIC.  AFTER THAT TIME...A
WEAKNESS IN THE RIDGE SHOULD ALLOW A TRACK MORE TO THE WEST-
NORTHWEST...WHICH WOULD BRING FLORENCE A FEW HUNDRED MILES TO THE
NORTHEAST OF THE LESSER ANTILLES.  WHILE THE ECMWF IS A SOUTHERN
OUTLIER...THE REST OF THE GUIDANCE HAS COME INTO VERY GOOD
AGREEMENT ON THE PATH OF THE STORM.  THE LATEST NHC TRACK FORECAST
IS SHIFTED TO THE SOUTH AT ALL FORECAST TIMES...BUT REMAINS ON THE
NORTHERN SIDE OF THE GUIDANCE ENVELOPE THROUGH DAY 3.


FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 16.5N  35.6W   50 KT  60 MPH
 12H  06/0000Z 16.7N  37.5W   50 KT  60 MPH
 24H  06/1200Z 16.9N  40.1W   50 KT  60 MPH
 36H  07/0000Z 17.4N  43.0W   45 KT  50 MPH
 48H  07/1200Z 18.0N  46.2W   45 KT  50 MPH
 72H  08/1200Z 19.5N  53.0W   35 KT  40 MPH
 96H  09/1200Z 21.5N  59.0W   30 KT  35 MPH
120H  10/1200Z 24.0N  64.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
FORECASTER BLAKE


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