000 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