ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM PRISCILLA DISCUSSION NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL EP162013 800 AM PDT MON OCT 14 2013 INFRARED AND MICROWAVE SATELLITE IMAGERY CONTINUE TO INDICATE THAT THE LOW-LEVEL CENTER OF PRISCILLA IS LOCATED ON THE NORTHEASTERN EDGE OF THE DEEP CONVECTION. ALTHOUGH SUBJECTIVE DVORAK ESTIMATES ARE BETWEEN 30-35 KT...THE EARLIER ASCAT DATA SHOWED WINDS BETWEEN 35-40 KT...AND THE MOST RECENT OBJECTIVE ADT ESTIMATE IS T2.9/43 KT. THE LATTER TWO ESTIMATES SUGGEST AN INITIAL INTENSITY OF 40 KT. ENVIRONMENTAL CONDITIONS ARE CURRENTLY ONLY MARGINALLY CONDUCIVE FOR ADDITIONAL STRENGTHENING DUE TO 20 KT OF EASTERLY SHEAR. THE SHEAR IS FORECAST TO RELAX IN ABOUT 12 HOURS OR SO...AND PRISCILLA SHOULD REMAIN OVER WATER OF AT LEAST 26C THROUGH 48 HOURS. AT THE SAME TIME...HOWEVER...SIGNIFICANT STRENGTHENING COULD BE LIMITED BY INGESTION OF DRIER AIR WHILE THE CYCLONE MOVES NORTHWARD. BY DAY 3...INCREASING WEST-SOUTHWESTERLY SHEAR...COLDER WATER...AND MORE STABLE AND DRIER AIR SHOULD ALL INDUCE QUICK WEAKENING. THE INTENSITY GUIDANCE FOR THIS FORECAST IS HIGHER THAN IN THE PREVIOUS CYCLE...AND IN FACT THE GFDL AND HWRF MODELS BRING PRISCILLA NEAR OR AT HURRICANE STRENGTH IN A COUPLE OF DAYS. THE NHC INTENSITY FORECAST IS A LITTLE HIGHER THAN THE PREVIOUS ONE AND IS CLOSE TO THE SHIPS AND LGEM MODELS. PRISCILLA HAS TURNED NORTHWARD ALONG THE WESTERN PERIPHERY OF A MID-LEVEL ANTICYCLONE CENTERED OVER EASTERN MEXICO...AND ITS INITIAL MOTION IS 010/9 KT. THE STORM IS FORECAST TO CONTINUE MOVING NORTHWARD DURING THE NEXT DAY OR SO UNTIL THE BREAK IN THE RIDGE ALONG 120W FILLS IN AND FORCES PRISCILLA TO SLOW DOWN AND TURN NORTHWESTWARD. A SIGNIFICANT WESTWARD SHIFT IN THE TRACK GUIDANCE OCCURRED ON THIS FORECAST CYCLE...WHICH REQUIRED A FAIRLY SIZEABLE WESTWARD ADJUSTMENT OF THE OFFICIAL TRACK FORECAST AS WELL. IT SHOULD BE NOTED THAT THE UPDATED NHC FORECAST STILL LIES EAST OF THE GFS...ECMWF...AND THE MULTI-MODEL CONSENSUS TVCE...SO AN ADDITIONAL ADJUSTMENT MAY BE REQUIRED LATER TODAY. FORECAST POSITIONS AND MAX WINDS INIT 14/1500Z 15.2N 115.5W 40 KT 45 MPH 12H 15/0000Z 16.2N 115.5W 45 KT 50 MPH 24H 15/1200Z 17.3N 116.1W 50 KT 60 MPH 36H 16/0000Z 18.2N 117.1W 50 KT 60 MPH 48H 16/1200Z 19.0N 118.2W 50 KT 60 MPH 72H 17/1200Z 20.5N 119.5W 40 KT 45 MPH 96H 18/1200Z 21.0N 120.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 19/1200Z 20.5N 121.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ FORECASTER BERG NNNN