540 WTPZ45 KNHC 140249 TCDEP5 Hurricane Darby Discussion Number 19 NWS National Hurricane Center Miami FL EP052022 Issued by NWS Central Pacific Hurricane Center Honolulu HI 500 PM HST Wed Jul 13 2022 Darby continues to be a healthy tropical cyclone. In fact, the subjective intensity estimates from PHFO, TAFB, and SAB, and the objective ADT and CIMSS SATCON all came it at 102 kt. Based on this consensus, the initial intensity has been increased to 100 kt, making Darby a major hurricane once again. Satellite images from the past couple of hours indicated that the upper level outflow has started to become a bit asymmetric, which may indicate that Darby is starting to be affected by the large upper level trough to the northwest. The initial motion is 285/14 kt. The cyclone is being steered by a low- to mid-level ridge to the north of the system. This ridge is expected to maintain a general west-northwest motion over the next 24 hours or so. As Darby becomes impacted by vertical shear, it will weaken over the next 24 to 48 hours. As it becomes an increasingly shallow system, it should turn toward the west. The trusted dynamical models are in agreement with this scenario and are in a tightly clustered guidance envelope. The forecast track has also been quite consistent for several cycles, and current forecast follows the previous package with a slight northward shift based on recent movement trends. Sea surface temperatures (SSTs) are between 25-26C around Darby and should remain marginal along the forecast track. The main question is when the forecasted vertical shear will begin to significantly affect the system. The combination of this vertical shear, marginal SSTs, and drier low- to mid-tropospheric air should result in a rapid weakening of Darby, especially considering the small size of the cyclone. Simulated IR data from the GFS and HWRF indicated that Darby could maintain an eye tonight, but it would finally collapse some time Thursday, with the low level circulation becoming exposed on Friday. The main intensity aids are projecting a rapid weakening over the next 3 days despite the recent intensification. The forecast for this advisory is consistent with the previous forecast and has Darby resuming its weakening trend soon, becoming a post-tropical/remnant low in 72 hours. FORECAST POSITIONS AND MAX WINDS INIT 14/0300Z 15.9N 138.5W 100 KT 115 MPH 12H 14/1200Z 16.3N 140.3W 90 KT 105 MPH 24H 15/0000Z 16.8N 142.9W 80 KT 90 MPH 36H 15/1200Z 17.0N 145.4W 65 KT 75 MPH 48H 16/0000Z 17.0N 148.2W 55 KT 65 MPH 60H 16/1200Z 16.8N 151.4W 40 KT 45 MPH...POST-TROPICAL 72H 17/0000Z 16.7N 154.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 18/0000Z...DISSIPATED $$ Forecaster Kodama/M Ballard