612 WTPA41 PHFO 150849 TCDCP1 Hurricane Darby Discussion Number 24 NWS Central Pacific Hurricane Center Honolulu HI EP052022 1100 PM HST Thu Jul 14 2022 Darby's satellite presentation has deteriorated this evening as it continues to be influenced by moderate west-southwesterly vertical wind shear of around 20 knots as indicated by UW-CIMSS vertical wind shear analysis, and cool sea surface temperatures (SSTs) of around 25C shown in the NASA SPoRT SST composite. The latest subjective Dvorak current intensity estimates from PHFO/SAB/JTWC ranged from 4.0 (65 knots) to 4.5 (77 knots) while the UW-CIMSS objective ADT current intensity estimate was 3.8 (61 knots). Additionally, a SATCON estimate at 14/0404Z estimated the cyclones strength at 64 knots. Given the satellite degradation and incorporating a blend of the above intensity estimates, Darby's initial intensity has been lowered to 65 knots with this advisory. Darby continues on its westward course, with the estimated initial motion set at 280/14 knots. Darby will remain in a hostile environment during the next couple days, characterized by cool SSTs of 25-26C, moderate to strong westerly vertical wind shear of 20 to 30 knots, and surrounded by dry mid-level air with relative humidity values of less than 50 percent. As a result, we expect Darby to continue to steadily weaken during the next couple days. The tropical cyclone is expected to weaken into a tropical storm later tonight, then weaken further into a remnant low late Saturday, before dissipating Saturday night. The intensity forecast has been lowered based on the rapid rate of weakening the system is experiencing, and follows a blend of the dynamical and statistical intensity guidance. The tropical cyclone will continue to be directed westward during the next couple days, influenced initially by a gradually building mid and upper level ridge to the north of the system, while deep convection persists. The cyclone will then begin to move slightly south of due west at a faster forward speed as deep convection becomes more sporadic, allowing Darby to be pushed along by the low level trade wind flow. The forecast track closely follows a blend of the latest GFS and ECMWF guidance (GFEX) through dissipation, and is nearly a carbon copy of the previous official forecast track. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 17.5N 144.8W 65 KT 75 MPH 12H 15/1800Z 17.6N 147.0W 55 KT 65 MPH 24H 16/0600Z 17.6N 150.3W 45 KT 50 MPH 36H 16/1800Z 17.5N 154.0W 35 KT 40 MPH 48H 17/0600Z 17.2N 157.8W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 17/1800Z...DISSIPATED $$ Forecaster Jelsema