ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION FIFTEEN-E DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 PM PDT WED SEP 28 2005 TROPICAL DEPRESSION FIFTEEN-E IS ALMOST TO TROPICAL STORM STRENGTH. BURSTS OF CONVECTION ARE OCCURRING WEST THROUGH SOUTH OF THE EXPOSED LOW-LEVEL CENTER...WITH ENOUGH ORGANIZATION TO PRODUCE SATELLITE INTENSITY ESTIMATES OF 35 KT FROM TAFB AND 30 KT FROM SAB AND AFWA. ADDITIONALLY...A SHIP 125 N MI SOUTH-SOUTHEAST OF THE CENTER REPORTED 30 KT. SINCE THE CONSENSUS OF THE INTENSITY ESTIMATES IS BELOW TROPICAL STORM STRENGTH...THE SYSTEM REMAINS A 30 KT DEPRESSION FOR THIS ADVISORY. THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 275/5. THE CYCLONE IS ON THE SOUTH SIDE OF A MID/UPPER-LEVEL RIDGE THAT CURRENTLY EXTENDS WESTWARD FROM NORTHERN MEXICO ALONG 26N. THE GFS...GFDL...NOGAPS... AND CANADIAN MODELS INDICATE THIS RIDGE SHOULD WEAKEN IN 36-48 HR AS A MID/UPPER-LEVEL LOW FORMS WEST OF SOUTHERN CALIFORNIA. THESE MODELS CALL FOR THE DEPRESSION TO GRADUALLY TURN NORTHWEST AND NORTHWARD DURING THE NEXT FIVE DAYS...PASSING NEAR OR OVER BAJA CALIFORNIA. ON THE OTHER HAND...THE UKMET...THE ECMWF... AND THE GFDN KEEP ENOUGH OF A RIDGE BETWEEN THE DEPRESSION AND THE TROUGH TO MOVE THE DEPRESSION MORE TOWARD THE WEST-NORTHWEST AWAY FROM LAND. SINCE EVEN THE UKMET AND ECMWF SHOW A SIGNIFICANT TROUGH OFF THE CALIFORNIA COAST...THE FORECAST TRACK WILL LEAN TOWARD THE GFS/ GFDL/NOGAPS/CANADIAN SOLUTION...CALLING FOR A NORTHWESTWARD MOTION BY 24-36 HR AND A NORTHWARD MOTION BY 96-120 HR. THE NEW FORECAST TRACK IS CLOSE TO THE PREVIOUS PACKAGE AND ALONG THE LEFT SIDE OF THE NORTHWARD-POINTING GUIDANCE IN BEST AGREEMENT WITH THE NOGAPS. ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN SHOW 15-20 KT OF EASTERLY VERTICAL SHEAR HINDERING DEVELOPMENT. LARGE-SCALE MODELS AGREE THAT THE SHEAR WILL DECREASE AS THE DEPRESSION APPROACHES THE AXIS OF THE UPPER-LEVEL RIDGE...WHICH SHOULD ALLOW STRENGTHENING BEFORE THE CYCLONE REACHES COOLER SEA SURFACE TEMPERATURES IN 72 HR OR SO. THE GFDL BRINGS THE SYSTEM TO HURRICANE STRENGTH IN 24 HR...WHICH LOOKS A LITTLE UNLIKELY GIVEN CURRENT TRENDS. THE SHIPS MODEL CALLS FOR MUCH LESS INTENSIFICATION...WITH A PEAK INTENSITY OF ABOUT 50 KT IN 60-72 HR. THE INTENSITY FORECAST WILL BLEND THE GFDL AND SHIPS...CALLING FOR THE DEPRESSION TO BECOME A TROPICAL STORM IN 12 HR AND A HURRICANE IN 72 HR. AFTER 72 HR...COOL SSTS ALONG THE FORECAST TRACK SHOULD CAUSE WEAKENING. AS MENTIONED IN THE PREVIOUS PACKAGE...AFTER 72 HR THE CYCLONE WILL BE MOVING ALMOST PARALLEL TO THE SST ISOTHERMS. THUS...ANY DEVIATION FROM THE FORECAST TRACK COULD MAKE A LARGE DIFFERENCE IN HOW WARM/COOL THE WATER IS UNDER THE CYCLONE. THE 12 FT SEAS RADII WERE REVISED IN THE SOUTHEASTERN QUADRANT BASED ON THE SHIP REPORT. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 29/0300Z 17.1N 107.1W 30 KT 12HR VT 29/1200Z 17.5N 108.2W 35 KT 24HR VT 30/0000Z 18.3N 109.5W 40 KT 36HR VT 30/1200Z 19.2N 110.7W 45 KT 48HR VT 01/0000Z 20.1N 111.6W 55 KT 72HR VT 02/0000Z 22.0N 113.0W 65 KT 96HR VT 03/0000Z 24.0N 114.0W 55 KT 120HR VT 04/0000Z 26.5N 114.5W 45 KT $$ NNNN
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Page last modified: Thursday, 29-Sep-2005 02:55:24 UTC