000 WTNT43 KNHC 172051 TCDAT3 TROPICAL STORM GORDON DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012 500 PM AST FRI AUG 17 2012 THE SATELLITE PRESENTATION OF GORDON HAS IMPROVED SINCE THE LAST ADVISORY. THE CENTER OF CIRCULATION IS NOW EMBEDDED BENEATH A CENTRAL DENSE OVERCAST WITH A BAND OF CONVECTION CURLING AROUND TO THE EAST. DVORAK ESTIMATES HAVE INCREASED FROM THIS MORNING...AND THEY ARE NOW MORE SUPPORTIVE OF THE 55-KT INITIAL INTENSITY. THE WIND RADII HAVE BEEN INCREASED A BIT BASED ON AMSU DATA FROM EARLIER IN THE DAY. GORDON IS FULLY EMBEDDED WITHIN THE MID-LATITUDE WESTERLIES...MOVING EASTWARD WITH A MOTION OF 095/17 KT. THE CYCLONE IS EXPECTED TO CONTINUE MOVING QUICKLY EASTWARD THROUGH 72 HOURS AS IT MOVES INTO THE BASE OF AN AMPLIFIED TROUGH OVER THE NORTHEASTERN ATLANTIC. AFTER THAT...GORDON SHOULD BE A WEAKER CYCLONE...AND IT WILL LIKELY TURN EAST-SOUTHEASTWARD BY DAY 5 AS IT BECOMES STEERED BY LOWER-LEVEL NORTHERLY FLOW. THE TRACK GUIDANCE IS TIGHTLY CLUSTERED THROUGH MUCH OF THE FORECAST PERIOD...ESPECIALLY WITHIN THE FIRST 72 HOURS AS THE CYCLONE APPROACHES THE AZORES. THE OFFICIAL NHC TRACK FORECAST LIES BETWEEN THE GFS AND ECMWF SOLUTIONS AND IS A LITTLE FASTER THAN THE HFIP MULTI-MODEL CONSENSUS TV15. THE VERTICAL SHEAR IS NOT EXPECTED TO BE TOO DETRIMENTAL FOR SOME STRENGTHENING WHILE GORDON REMAINS OVER WATERS WARMER THAN 26C FOR THE NEXT 36 HOURS OR SO. THE DEEP-LAYER SHEAR IS EXPECTED TO INCREASE ABOVE 30 KT BY 48 HOURS...AND WEAKENING SHOULD HAVE COMMENCED BY THAT TIME. GORDON SHOULD THEN COMPLETE EXTRATROPICAL TRANSITION IN ABOUT 72 HOURS...AFTER IT HAS ALREADY PASSED THE AZORES. THERE IS SOME UNCERTAINTY IN THE INTENSITY FORECAST DURING THE FIRST 48 HOURS...WITH MANY OF THE DYNAMICAL MODELS MAKING GORDON A HURRICANE WHILE THE STATISTICAL SHIPS AND LGEM MODELS SHOW VERY LITTLE STRENGTHENING. THE OFFICIAL INTENSITY FORECAST BRINGS GORDON JUST BELOW HURRICANE STRENGTH...BUT IT WOULD NOT BE SURPRISING IF IT DID BECOME A HURRICANE DURING THE NEXT DAY OR SO. IN FACT...BASED ON PAST NHC INTENSITY ERRORS...THERE IS A 1 IN 3 CHANCE THAT GORDON COULD BE A HURRICANE AT THE 24- AND 36-HOUR FORECAST PERIODS. BASED ON THE NEW FORECAST...GORDON WILL BE APPROACHING THE AZORES AS A TROPICAL CYCLONE IN 48 HOURS. THE GOVERNMENT OF PORTUGAL HAS THEREFORE ISSUED A TROPICAL STORM WATCH FOR THE CENTRAL AND EASTERN AZORES. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 34.3N 44.0W 55 KT 65 MPH 12H 18/0600Z 34.1N 41.2W 55 KT 65 MPH 24H 18/1800Z 34.2N 37.3W 60 KT 70 MPH 36H 19/0600Z 34.7N 33.0W 60 KT 70 MPH 48H 19/1800Z 35.8N 28.9W 55 KT 65 MPH 72H 20/1800Z 38.5N 21.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 21/1800Z 39.5N 17.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 22/1800Z 38.5N 14.0W 25 KT 30 MPH...POST-TROP/EXTRATROP $$ FORECASTER BERG/AVILA