ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM HURRICANE DARBY DISCUSSION NUMBER 25 NWS NATIONAL HURRICANE CENTER MIAMI FL EP052016 200 PM PDT SUN JUL 17 2016 Darby's eye has filled in during the day, and microwave data indicate that the eyewall has opened up on its southeastern side. Dvorak estimates are slowly coming down, and the initial intensity is lowered to 80 kt based on Dvorak Current Intensity numbers which range from 77-90 kt from SAB, TAFB, and UW-CIMSS ADT. The center of Darby is approaching the 24C SST isotherm, and it should reach waters around 23C in about 12 hours. After that time, SSTs will slowly warm up to between 26-27C by the end of the forecast period. Vertical shear is expected to remain low for another 2-3 days and then increase to around 20 kt from the west by day 5. Considering all these factors, fairly quick weakening is expected during the next 24 hours while Darby is over the coldest water, followed by more gradual weakening through day 5. The NHC intensity forecast closely follows the ICON intensity consensus for the entire forecast period, and Darby is likely to weaken to a tropical storm in about 24 hours. The initial motion is 275/8 kt. Darby is expected to gain some latitude through day 3 and then lose latitude on days 4 and 5, but the ridge to the north should maintain the cyclone on a general westward heading for the entire forecast period. The track guidance remains tightly clustered with no noteworthy shifts in the overall envelope on this forecast cycle. The updated NHC forecast is therefore very similar to the previous one and is close to a consensus of the GFS and ECMWF models. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 18.3N 128.3W 80 KT 90 MPH 12H 18/0600Z 18.5N 129.9W 70 KT 80 MPH 24H 18/1800Z 18.8N 132.0W 60 KT 70 MPH 36H 19/0600Z 19.2N 134.4W 55 KT 65 MPH 48H 19/1800Z 19.6N 136.7W 50 KT 60 MPH 72H 20/1800Z 19.8N 141.4W 40 KT 45 MPH 96H 21/1800Z 19.0N 146.0W 35 KT 40 MPH 120H 22/1800Z 18.0N 150.5W 35 KT 40 MPH $$ Forecaster Berg NNNN