[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 310252
TCDAT3
TROPICAL STORM FIONA DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082010
1100 PM EDT MON AUG 30 2010

CONVECTION HAS INCREASED IN THE NORTHWESTERN PORTION OF FIONA THIS
EVENING. HOWEVER...OVERALL THE SYSTEM LOOKS FAIRLY DISORGANIZED
WITH JUST A FEW WEAK BANDING FEATURES. A NOAA/NTAS BUOY LOCATED
NEAR THE CENTER REPORTED A PRESSURE OF 1008 MB A FEW HOURS
AGO...WHICH IS ABOUT THE SAME PRESSURE AS BUOY 41041 MEASURED
EARLIER TODAY. THUS...THE INITIAL INTENSITY WILL REMAIN 35 KT FOR
THIS ADVISORY. GIVEN THE CURRENT DISHEVELED APPEARANCE OF FIONA...
ONLY A SLOW INCREASE IN STRENGTH IS FORECAST FOR THE NEXT DAY OR SO
WHILE THE TROPICAL CYCLONE MOVES OVER VERY WARM WATER AND LIGHT
SHEAR. AFTER THAT TIME...NORTHEASTERLY SHEAR INCREASES MARKEDLY AND
MAY HALT ANY FURTHER DEVELOPMENT...PLUS THE CYCLONE COULD BE MOVING
OVER COOLER WATERS THAT WERE UPWELLED BY EARL. MOST OF THE
MODELS...SAVE THE GFDL/GFDN...ARE IN CLOSE AGREEMENT WITH THIS
SCENARIO...AND THE OFFICIAL NHC INTENSITY FORECAST IS NEAR THE
PREVIOUS ONE BUT BELOW THE INTENSITY CONSENSUS. HOWEVER...I DO NOT
HAVE A LOT OF CONFIDENCE IN THE FORECAST AT THIS TIME.

MICROWAVE AND SURFACE DATA SUGGEST THE CENTER IS MOVING 280/21.
FIONA SHOULD MOVE AROUND THE SOUTHWESTERN PERIPHERY OF A RIDGE OVER
THE CENTRAL ATLANTIC...EVENTUALLY TURNING TO THE WEST-NORTHWEST AND
NORTHWEST IN THE NEXT COUPLE OF DAYS.  THE TRACK MODELS ARE FAIRLY
WELL CLUSTERED...EXCEPT FOR THE ECMWF.  THAT MODEL IS ON THE LEFT
SIDE OF THE GUIDANCE ENVELOPE...PERHAPS BECAUSE IT SHOWS A DEEPER
FIONA RESPONDING TO STRONGER UPPER-LEVEL NORTHEASTERLY WINDS.
SINCE WE ARE NOT EXPECTING THAT SCENARIO...THE NHC FORECAST IS VERY
CLOSE TO THE PREVIOUS ONE...AND IS A LITTLE SOUTH OF THE MODEL
CONSENSUS.


FORECAST POSITIONS AND MAX WINDS

INITIAL      31/0300Z 15.1N  50.8W    35 KT
 12HR VT     31/1200Z 15.7N  54.0W    35 KT
 24HR VT     01/0000Z 16.9N  57.7W    40 KT
 36HR VT     01/1200Z 18.4N  60.6W    45 KT
 48HR VT     02/0000Z 20.5N  63.2W    45 KT
 72HR VT     03/0000Z 25.0N  67.0W    45 KT
 96HR VT     04/0000Z 28.0N  69.0W    45 KT
120HR VT     05/0000Z 29.0N  69.5W    45 KT

$$
FORECASTER BLAKE



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