000 WTPZ44 KNHC 170311 TCDEP4 TROPICAL STORM MIRIAM DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP142006 800 PM PDT SAT SEP 16 2006 CONVENTIONAL SATELLITE IMAGERY INDICATES CONTINUED AND DEEPENING CONVECTION SOUTH OF TROPICAL STORM MIRIAM...SLOWLY SHIFTING NORTHEASTWARD OVER THE PARTIALLY EXPOSED LOW LEVEL CIRCULATION... AND SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 45 AND 35 KT RESPECTIVELY. AND THE INITIAL INTENSITY OF 40 KT IS A BLEND OF THESE ESTIMATES. WHILE TROPICAL STORM MIRIAM HAS TAKEN A MORE NORTHWARD JOG...CURRENT MOTION IS 020/2. THE STORM IS STILL DRIFTING IN A GENERALLY NORTHEAST DIRECTION...CONSISTENT WITH THE SOUTHWESTERLY FLOW SOUTH OF THE CENTER THAT IS PART OF THE LARGE-SCALE TROUGH CONTAINING BOTH TROPICAL STORM MIRIAM AND HURRICANE LANE. THE TRACK FORECAST IS SLOWER THAN IN THE PREVIOUS ADVISORY AT DAYS 4 AND 5 AND MORE CLOSELY FOLLOWS MODEL CONSENSUS GIVEN THE LACK OF CONSISTENCY IN THE GUIDANCE. NONE OF THE GLOBAL MODELS MAINTAIN SIGNIFICANT SURFACE WINDS IN THE NEXT 48 HOURS...AND EVEN THE GFDL MODEL...INITIALIZED WITH THE STRONGEST CYCLONE OF ALL THE MODELS...FORECASTS ONLY SLIGHT STRENGTHENING IN THE NEXT 24-36 HOURS. THE SHIPS MODEL INDICATES LITTLE OR NO INTENSIFICATION AND THEN DISSIPATION IN 3-4 DAYS. THE DOMINANT NEGATIVE INTENSITY FACTOR IS INTRUSION OF DRY STABLE MARITIME AIR. FORECAST POSITIONS AND MAX WINDS INITIAL 17/0300Z 18.4N 114.4W 40 KT 12HR VT 17/1200Z 18.8N 114.0W 40 KT 24HR VT 18/0000Z 19.5N 113.3W 40 KT 36HR VT 18/1200Z 20.6N 113.0W 45 KT 48HR VT 19/0000Z 21.6N 113.1W 40 KT 72HR VT 20/0000Z 23.1N 113.7W 35 KT 96HR VT 21/0000Z 24.5N 114.5W 25 KT...DISSIPATING 120HR VT 22/0000Z 26.0N 115.5W 20 KT...REMNANT LOW $$ FORECASTER FIORINO/STEWART 000 WTPZ44 KNHC 170311 TCDEP4 TROPICAL STORM MIRIAM DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP142006 800 PM PDT SAT SEP 16 2006 CONVENTIONAL SATELLITE IMAGERY INDICATES CONTINUED AND DEEPENING CONVECTION SOUTH OF TROPICAL STORM MIRIAM...SLOWLY SHIFTING NORTHEASTWARD OVER THE PARTIALLY EXPOSED LOW LEVEL CIRCULATION... AND SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 45 AND 35 KT RESPECTIVELY. AND THE INITIAL INTENSITY OF 40 KT IS A BLEND OF THESE ESTIMATES. WHILE TROPICAL STORM MIRIAM HAS TAKEN A MORE NORTHWARD JOG...CURRENT MOTION IS 020/2. THE STORM IS STILL DRIFTING IN A GENERALLY NORTHEAST DIRECTION...CONSISTENT WITH THE SOUTHWESTERLY FLOW SOUTH OF THE CENTER THAT IS PART OF THE LARGE-SCALE TROUGH CONTAINING BOTH TROPICAL STORM MIRIAM AND HURRICANE LANE. THE TRACK FORECAST IS SLOWER THAN IN THE PREVIOUS ADVISORY AT DAYS 4 AND 5 AND MORE CLOSELY FOLLOWS MODEL CONSENSUS GIVEN THE LACK OF CONSISTENCY IN THE GUIDANCE. NONE OF THE GLOBAL MODELS MAINTAIN SIGNIFICANT SURFACE WINDS IN THE NEXT 48 HOURS...AND EVEN THE GFDL MODEL...INITIALIZED WITH THE STRONGEST CYCLONE OF ALL THE MODELS...FORECASTS ONLY SLIGHT STRENGTHENING IN THE NEXT 24-36 HOURS. THE SHIPS MODEL INDICATES LITTLE OR NO INTENSIFICATION AND THEN DISSIPATION IN 3-4 DAYS. THE DOMINANT NEGATIVE INTENSITY FACTOR IS INTRUSION OF DRY STABLE MARITIME AIR. FORECAST POSITIONS AND MAX WINDS INITIAL 17/0300Z 18.4N 114.4W 40 KT 12HR VT 17/1200Z 18.8N 114.0W 40 KT 24HR VT 18/0000Z 19.5N 113.3W 40 KT 36HR VT 18/1200Z 20.6N 113.0W 45 KT 48HR VT 19/0000Z 21.6N 113.1W 40 KT 72HR VT 20/0000Z 23.1N 113.7W 35 KT 96HR VT 21/0000Z 24.5N 114.5W 25 KT...DISSIPATING 120HR VT 22/0000Z 26.0N 115.5W 20 KT...REMNANT LOW $$ FORECASTER FIORINO/STEWART