000 WTPZ45 KNHC 120233 TCDEP5 Hurricane Darby Discussion Number 11 NWS National Hurricane Center Miami FL EP052022 500 PM HST Mon Jul 11 2022 Darby has been generally steady in strength during the past several hours and remains a category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. It maintains a classic major hurricane structure with well-defined outflow in all quadrants, a symmetric cloud pattern, and a distinct small eye (less than 10 n mi in diameter). Satellite images indicate that the eye has become even more defined over the past few hours, but deep convection has been weakening a little to the west of the eye. All of the satellite intensity estimates have plateaued and suggest that Darby still has peak winds of around 120 kt. Although the hurricane is very powerful, it is quite compact with tropical-storm-force winds estimated to only extend 50 n mi from the center. The hurricane has been moving westward, or 275 degrees, at 15 kt. A general west to west-northwest motion at a slightly slower pace is expected during the next few days as Darby continues to move on the south or southwest side of a mid-level ridge, taking the system into the central Pacific basin in 60-72 hours. After that time, the weakening system is expected to be steered due westward by the low-level flow. There are some speed differences in the models, but they generally show the same theme. This forecast lies near the middle of the guidance envelope, and roughly between the GFS and ECMWF models. Darby is likely near its peak intensity. The major hurricane will be moving over progressively cooler waters and crossing the 26 degree C isotherm in about 24 hours. In addition, Darby will be moving into a drier airmass, which should accelerate the weakening trend. In a few days when Darby is over the central Pacific, a mid- to upper-level trough should induce strong westerly shear and cause Darby to become a post-tropical cyclone in about 4 days. The NHC intensity forecast is similar to the previous one and fairly close to the IVCN and HCCA consensus models. FORECAST POSITIONS AND MAX WINDS INIT 12/0300Z 14.9N 126.6W 120 KT 140 MPH 12H 12/1200Z 15.0N 128.7W 120 KT 140 MPH 24H 13/0000Z 15.1N 131.3W 115 KT 130 MPH 36H 13/1200Z 15.5N 133.9W 100 KT 115 MPH 48H 14/0000Z 16.1N 136.4W 80 KT 90 MPH 60H 14/1200Z 16.7N 139.0W 65 KT 75 MPH 72H 15/0000Z 17.3N 141.6W 50 KT 60 MPH 96H 16/0000Z 17.6N 147.1W 35 KT 40 MPH...POST-TROPICAL 120H 17/0000Z 17.4N 153.5W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Cangialosi