ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM HURRICANE DARBY DISCUSSION NUMBER 19 NATIONAL WEATHER SERVICE MIAMI FL 2 PM PDT MON JUL 27 1998 THE INITIAL MOTION ESTIMATE IS 275/13. MOST OF THE TRACK GUIDANCE SHOWS AN INCREASING NORTHWARD COMPONENT OF MOTION WITH TIME... APPARENTLY DUE TO A 500-MB LOW INITIALIZED ON THE AVIATION MODEL NORTHWEST OF HAWAII. THE OFFICIAL FORECAST FOLLOWS THIS REASONING AND IS CLOSE TO THE UKMET AND GFDL MODELS. AGAIN THERE IS LITTLE CHANGE IN INTENSITY AS THE TRACK PARALLELS THE SST ISOPLETHS. HOWEVER GRADUAL WEAKENING IS EXPECTED TO BEGIN BY ABOUT 24 HOURS AS DARBY ENCOUNTERS SSTS IN THE 25 DEG C RANGE. LAWRENCE FORECAST POSITIONS AND MAX WINDS INITIAL 27/2100Z 16.9N 132.4W 100 KTS 12HR VT 28/0600Z 17.1N 134.4W 100 KTS 24HR VT 28/1800Z 17.6N 137.0W 90 KTS 36HR VT 29/0600Z 18.2N 139.8W 80 KTS 48HR VT 29/1800Z 18.9N 142.5W 70 KTS 72HR VT 30/1800Z 21.0N 148.0W 55 KTS NNNN