000 WTPZ42 KNHC 212035 TCDEP2 TROPICAL STORM IVO DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP122007 200 PM PDT FRI SEP 21 2007 IVO APPEARED TO BE IN A CONVECTIVE LULL ABOUT 5 OR 6 HOURS AGO... BUT A BURST OF DEEP CONVECTION HAS REDEVELOPED NORTHEAST OF THE LOW-LEVEL CIRCULATION CENTER DURING THE LAST COUPLE OF HOURS. DESPITE THE NEW CONVECTION AND A WELL-DEFINED CIRCULATION...DVORAK DATA T-NUMBERS AND CURRENT INTENSITY ESTIMATES FROM BOTH TAFB AND SAB ARE 55 KT AND 65 KT RESPECTIVELY. A 1356 UTC QUIKSCAT PASS ESTIMATED 50 TO 55 KT WIND VECTORS. BLENDING THE ABOVE ESTIMATES RESULTS IN LOWERING THE INITIAL INTENSITY TO 60 KT. WHILE THE WATERS ARE EXPECTED TO REMAIN SUFFICIENTLY WARM ALONG THE FORECAST TRACK...WESTERLY TO SOUTHWESTERLY SHEAR IS FORECAST TO GRADUALLY INCREASE. THE OFFICIAL INTENSITY FORECAST CALLS FOR SLOW WEAKENING AFTER 12 HOURS...WHICH FOLLOWS CLOSELY WITH THE INTENSITY MODEL CONSENSUS OF THE GFDL...SHIPS...AND HWRF. IVO IS MOVING SLOWLY TO THE NORTH AND THE MOTION IS ESTIMATED AT 005/5. THE GENERAL TRACK PHILOSOPHY IS COMPLICATED AND SOLUTIONS FROM THE VARIOUS MODELS ARE HIGHLY DIVERGENT. THE MID- TO UPPER- LEVEL LOW REMAINS CENTERED JUST WEST OF THE SOUTHERN CALIFORNIA COAST. AS THE LOW LIFTS NORTHEASTWARD IN ABOUT 36 HOURS OR SO...IT IS DIFFICULT TO DETERMINE HOW MUCH INFLUENCE THE LINGERING TROUGH BEHIND THE LOW WILL HAVE ON STEERING IVO NORTHEASTWARD. ONLY THE UKMET AND NOGAPS MODELS ACCELERATE THE CYCLONE NORTHEASTWARD INTO MAINLAND MEXICO. THE ECMWF...GFS...HWRF...AND GFDL MODELS STALL IVO SOUTH OF THE BAJA PENINSULA COAST IN ABOUT 3 DAYS. THE OFFICIAL TRACK FORECAST STILL CALLS FOR IVO TO MOVE ACROSS THE SOUTHERN BAJA PENINSULA... BUT AT A SLOWER PACE AND SLIGHTLY TO THE EAST OF THE PREVIOUS FORECAST...WHICH IS CLOSEST TO THE FSSE GUIDANCE. ONCE AGAIN...GIVEN THE UNCERTAINTY PRESENT IN THE OFFICIAL FORECAST...INTERESTS IN SOUTHERN BAJA CALIFORNIA SHOULD CLOSELY MONITOR THE PROGRESS OF IVO. FORECAST POSITIONS AND MAX WINDS INITIAL 21/2100Z 20.1N 113.4W 60 KT 12HR VT 22/0600Z 20.8N 113.2W 60 KT 24HR VT 22/1800Z 21.6N 112.9W 55 KT 36HR VT 23/0600Z 22.3N 112.6W 50 KT 48HR VT 23/1800Z 23.0N 112.2W 45 KT 72HR VT 24/1800Z 24.0N 111.5W 40 KT 96HR VT 25/1800Z 25.0N 111.0W 30 KT...INLAND 120HR VT 26/1800Z 26.0N 110.5W 25 KT $$ FORECASTER MAINELLI