000 WTPA41 PHFO 141458 TCDCP1 Hurricane Darby Discussion Number 21 NWS Central Pacific Hurricane Center Honolulu HI EP052022 500 AM HST Thu Jul 14 2022 Darby crossed longitude 140W and officially entered the central Pacific basin just after midnight HST this morning. The cyclone's satellite appearance has gone through some fluctuations since the previous advisory, but an elongated and somewhat ragged 5-10 nm wide eye has persisted. Pulsing convection continues to encircle the center, but has become much less symmetric. The initial intensity is estimated to be 90 kt, supported by a blend of the subjective Dvorak intensity estimates from SAB and HFO, the latest UW-CIMSS objective Dvorak estimate of 87 kt, and a SATCON near 83 kt. Darby lies on the southwestern periphery of a ridge aloft, in an area characterized by moderate southerly vertical wind shear. Darby is moving closer to an upper-level trough to its northwest, into an environment characterized by even stronger vertical wind shear, as evidenced by transverse banding in the northwest semicircle. This shear will allow the cyclone to efficiently ingest the dry mid-level air that prevails, while moving over sub-26C SSTs. Since Darby continues to be a small system, it will quickly respond to the debilitating environment into which it is moving, with rapid weakening expected over the next 48 hours before dissipation occurs by 72 hours. The updated intensity forecast closely follows the consensus IVCN, as well as the SHIPS guidance. The initial motion estimate for this advisory is 290/14kt. As Darby degrades to a shallow system over the next 48 hours, a persistent strong surface high north of Hawaii will force it to accelerate as it makes a turn toward the west. The updated track forecast is close to the previous forecast, and lies very close to the GFEX. FORECAST POSITIONS AND MAX WINDS INIT 14/1500Z 16.6N 140.9W 90 KT 105 MPH 12H 15/0000Z 17.1N 142.9W 75 KT 85 MPH 24H 15/1200Z 17.2N 145.6W 60 KT 70 MPH 36H 16/0000Z 17.2N 148.7W 50 KT 60 MPH 48H 16/1200Z 17.1N 152.1W 40 KT 45 MPH 60H 17/0000Z 16.9N 155.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 17/1200Z...DISSIPATED $$ Forecaster Birchard