000 WTPZ41 KNHC 161439 TCDEP1 TROPICAL STORM FERNANDA DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL EP062011 800 AM PDT TUE AUG 16 2011 SATELLITE IMAGES INDICATE THAT TROPICAL DEPRESSION SIX-E HAS STRENGTHENED INTO A TROPICAL STORM. THE CENTER IS NOW EMBEDDED WITHIN CONVECTION...ALTHOUGH IT IS STILL ON THE NORTHEASTERN EDGE. THIS STRUCTURE IS CONFIRMED BY A TRMM PASS AT 0800 UTC WHICH SHOWED THE CENTER JUST TO THE NORTHEAST OF THE MAIN BANDING FEATURE. DVORAK ESTIMATES ARE 35 AND 45 KT FROM SAB/TAFB...SO THE INITIAL WINDS WILL BE INCREASED TO 40 KT. THE INTENSITY FORECAST FOR FERNANDA IS PROBLEMATIC. WHILE SHEAR IS FORECAST TO BE LIGHT FOR THE NEXT COUPLE OF DAYS...THE THERMODYNAMIC ENVIRONMENT IS MARGINAL WITH MORE STABLE AIR AND COOLER WATERS JUST TO THE NORTH. HOWEVER...THE GUIDANCE IS NOW SHOWING CONSIDERABLY MORE INTENSIFICATION...WITH THE SHIPS/LGEM/HWRF MODELS NEAR HURRICANE STRENGTH IN A COUPLE OF DAYS. AFTER THAT TIME...AN INCREASE IN SOUTHEASTERLY SHEAR ALONG WITH DECREASING SSTS SHOULD INDUCE A WEAKENING TREND. ALTHOUGH THE NEW NHC FORECAST IS HIGHER THAN THE PREVIOUS ONE...THE FORECAST WILL STAY LOWER THAN THE BULK OF THE GUIDANCE GIVEN HOW CLOSE FERNANDA IS TO MORE HOSTILE ENVIRONMENTAL CONDITIONS. THE STORM IS MOVING TOWARD THE WEST AT ABOUT 7 KT. A MID-LEVEL RIDGE TO THE NORTH IS FORECAST TO WEAKEN DURING THE NEXT FEW DAYS... WHICH SHOULD ALLOW FERNANDA TO GRADUALLY TURN TOWARD THE WEST-NORTHWEST. AFTER THAT TIME...A WEAKER CYCLONE IS EXPECTED TO TURN TOWARD THE WEST WITHIN THE LOWER-LEVEL TRADES. WHILE THE RELIABLE GUIDANCE IS PRETTY WELL-CLUSTERED FOR THE FIRST FEW DAYS...THERE ARE SOME SPEED DIFFERENCES. THE NHC FORECAST IS CLOSE TO AN AVERAGE OF THE PREVIOUS FORECAST...THE GFS AND ITS ENSEMBLE...GFDL...ECMWF...AND UKMET MODELS. THIS BLEND RESULTS IN A SOMEWHAT FASTER AND FARTHER WEST FORECAST THAN THE PREVIOUS ONE. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 12.3N 134.5W 40 KT 45 MPH 12H 17/0000Z 12.3N 135.6W 45 KT 50 MPH 24H 17/1200Z 12.5N 137.0W 50 KT 60 MPH 36H 18/0000Z 12.8N 138.3W 50 KT 60 MPH 48H 18/1200Z 13.2N 139.9W 45 KT 50 MPH 72H 19/1200Z 14.2N 143.3W 40 KT 45 MPH 96H 20/1200Z 14.5N 147.0W 35 KT 40 MPH 120H 21/1200Z 15.0N 151.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ FORECASTER BLAKE