000 WTPZ45 KNHC 200900 TCDEP5 TROPICAL STORM KIKO DISCUSSION NUMBER 22 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152007 200 AM PDT SAT OCT 20 2007 UNTIL ABOUT TWO HOURS AGO...KIKO WAS NOT PRODUCING ALL THAT MUCH DEEP CONVECTION...BUT A HEALTHY BURST HAS RECENTLY ERUPTED OVER THE NORTHWESTERN QUADRANT...OBSCURING THE LOW-LEVEL CENTER. SUBJECTIVE DVORAK INTENSITY ESTIMATES AT 06Z WERE 45-55 KT...WITH OBJECTIVE ESTIMATES FAVORING THE LOWER END OF THAT RANGE. GIVEN THE INCREASE IN CONVECTION SINCE THEN...THE ADVISORY INTENSITY IS RAISED SLIGHTLY TO 50 KT. THE ENVIRONMENT IS CONDUCIVE FOR STRENGTHENING...AND ESSENTIALLY ALL OF THE INTENSITY GUIDANCE FORECASTS KIKO TO BE NEAR HURRICANE STRENGTH IN A DAY OR TWO. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY IN CALLING FOR KIKO TO BECOME A HURRICANE IN ABOUT 24 HOURS GIVEN THE WEAK WIND SHEAR AND VERY WARM SSTS. THE FORECAST INTENSITY PEAKS AT 75 KT IN ABOUT 48 HOURS...WITH A GRADUAL DECLINE THEREAFTER AS SHEAR INCREASES AND SSTS EVENTUALLY COOL BENEATH THE CYCLONE. KIKO CONTINUES SLOWLY NORTHWESTWARD AT ABOUT 305/4...TO THE SOUTH OF A MID-LEVEL RIDGE OVER NORTHERN MEXICO. THAT RIDGE IS FORECAST BY ALL OF THE DYNAMICAL MODELS TO ERODE DURING THE NEXT 24 HOURS AS A DEEP-LAYER LOW PRESSURE SYSTEM ARRIVES OVER THE WESTERN UNITED STATES. ALL OF THE MODELS EVENTUALLY SHOW THAT SYSTEM PROCEEDING EASTWARD...ALLOWING A RIDGE TO BUILD ALONG THE WEST COAST OF MEXICO AND CALIFORNIA IN A FEW DAYS. IN RESPONSE TO THAT PATTERN CHANGE...THE MODELS REMAIN EXTREMELY DIVERGENT BEYOND ABOUT 36 HOURS. THE GFDL REMAINS ON THE RIGHT SIDE OF THE GUIDANCE ENVELOPE BUT HAS SHIFTED SLIGHTLY TO THE LEFT ON THE LATEST RUN...TAKING KIKO NORTHWESTWARD ACROSS THE SOUTHERN TIP OF BAJA CALIFORNIA IN 48-72 HOURS. THE GFS AND ECMWF GLOBAL MODELS ARE ON THE LEFT SIDE OF THE MODEL SPREAD...SHOWING A WESTWARD TURN WELL SOUTH OF BAJA CALIFORNIA IN ABOUT 24 HOURS. IT IS A LITTLE DIFFICULT FOR ME TO ANTICIPATE A WESTWARD TURN THAT SOON...GIVEN THAT KIKO SHOULD BE A DEEP SYSTEM WITH NO SIGNIFICANT MID-LEVEL RIDGE FORECAST TO ITS NORTH UNTIL ABOUT BEYOND 48 HOURS FROM NOW. THE NEW OFFICIAL TRACK FORECAST LEANS A LITTLE MORE TOWARD THE GFDL SOLUTION AND IS A BIT FASTER AND TO THE NORTH OF THE PREVIOUS FORECAST STARTING ON DAY 2...BUT IT STILL CALLS FOR KIKO TO TURN WESTWARD SOUTH OF THE SOUTHERN TIP OF BAJA CALIFORNIA. IT IS IMPORTANT TO EMPHASIZE THAT THIS TRACK FORECAST IS HIGHLY UNCERTAIN GIVEN THE TREMENDOUS MODEL SPREAD. FORECAST POSITIONS AND MAX WINDS INITIAL 20/0900Z 17.7N 106.1W 50 KT 12HR VT 20/1800Z 18.3N 106.8W 55 KT 24HR VT 21/0600Z 19.1N 107.5W 65 KT 36HR VT 21/1800Z 19.9N 108.2W 70 KT 48HR VT 22/0600Z 20.7N 108.9W 75 KT 72HR VT 23/0600Z 21.7N 110.7W 65 KT 96HR VT 24/0600Z 22.5N 113.5W 50 KT 120HR VT 25/0600Z 23.0N 117.0W 40 KT $$ FORECASTER KNABB