Tropical Depression SIX-E
ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION SIX-E DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 AM PDT FRI JUL 18 2003 THE INITIAL MOTION ESTIMATE IS 275/16. THE OFFICIAL FORECAST TRACK FOLLOWS THE GUIDANCE WHICH SHOWS A CLIMATOLOGICALLY NORMAL TRACK TOWARD THE WEST TO WEST-NORTHWEST AT 15 KNOTS OR SO. THIS IS THE RESULT OF STEERING BY A RIDGE OF HIGH PRESSURE TO THE NORTH OF THE SYSTEM FOR THE NEXT SEVERAL DAYS. AT THE BEGINNING OF THE FORECAST PERIOD...THE GFS MODEL DOES NOT SHOW THAT MUCH RIDGING TO THE NORTH...BUT THE INITIAL MOTION SUGGESTS THAT THERE IS. SATELLITE DVORAK CLASSIFICATIONS ARE 35 KNOTS FROM TAFB...SAB AND KGWC BASED ON A SMALL COLD CDO FEATURE. HOWEVER I AM RELUCTANT TO UPGRADE TO A STORM ON NIGHTTIME IMAGERY. RECENT SSMI...TRMM AND AMSU PASSES ARE NOT THAT IMPRESSIVE AND YESTERDAYS LAST VISIBLE IMAGERY SHOWED THE CENTER A LITTLE EAST OF THE CONVECTION. THE GUIDANCE DOES NOT DO MUCH WITH THE INTENSITY EXCEPT FOR THE SHIPS MODEL WHICH BRINGS THE WIND SPEED TO 60 KNOTS IN 48 HOURS. THE OFFICIAL FORECAST FOLLOWS THE SHIPS MODEL EXCEPT BRINGING THE WIND SPEED TO ONLY 55 KNOTS. INCREASING VERTICAL SHEAR AFTER 72 HOURS SHOULD CAUSE SOME WEAKENING. FORECASTER LAWRENCE FORECAST POSITIONS AND MAX WINDS INITIAL 18/0900Z 14.7N 109.6W 30 KT 12HR VT 18/1800Z 15.0N 112.0W 40 KT 24HR VT 19/0600Z 15.4N 115.2W 45 KT 36HR VT 19/1800Z 15.7N 118.6W 50 KT 48HR VT 20/0600Z 16.0N 122.0W 55 KT 72HR VT 21/0600Z 17.5N 128.0W 55 KT 96HR VT 22/0600Z 18.5N 134.0W 45 KT 120HR VT 23/0600Z 20.0N 139.0W 30 KT NNNN