000 WTPA43 PHFO 170241 TCDCP3 Tropical Storm Greg Discussion Number 13 NWS Central Pacific Hurricane Center Honolulu HI EP082023 500 PM HST Wed Aug 16 2023 Deep convection surrounding Greg continues to pulse under the influence of southeasterly vertical wind shear. This has displaced much of the convection to the north of a partially exposed low-level circulation center. Dvorak current intensity estimates range from 2.0/30 kt by SAB, to 3.5/35 kt out of JTWC, to 3.0/45 kt at HFO. Since a 2343 UTC CIMSS SATCON came in at 43 kt and CIMSS ADT was recently holding as high as 37 kt, a blend of the inputs supports keeping the official intensity at 40 kt for this advisory, though that may be generous. Greg remains on a relatively steady forward motion that is slightly north of due west, 280/11 kt. A low- to mid-level ridge far to the north will keep the tropical cyclone moving along a general westward track through Thursday night, causing Greg to pass well south of Hawaii. A turn toward the west-southwest is forecast on Friday as the weakening tropical cyclone is steered by a deepening ridge to the north. The official forecast track was altered little from the prior advisory and lies near TVCE in the middle of a tightly clustered guidance envelope. Relatively light, southerly vertical wind shear will likely produce only slow weakening of Greg over the next day or so. Beyond 24 hours, the dynamical guidance suggests steady weakening, likely due to a gradual increase in northerly vertical wind shear produced by a strengthening ridge aloft to the north. Conversely, the statistical guidance shows little short term change in Greg, followed by some strengthening. Given the tropical cyclone's inability to strengthen within the current shear environment and sufficiently warm SST, the official forecast follows the steady weakening trend of the dynamical guidance beyond 24 hours, and Greg is expected to become a post-tropical remnant low by late Friday or Saturday. FORECAST POSITIONS AND MAX WINDS INIT 17/0300Z 12.1N 153.5W 40 KT 45 MPH 12H 17/1200Z 12.2N 155.2W 40 KT 45 MPH 24H 18/0000Z 12.3N 157.6W 35 KT 40 MPH 36H 18/1200Z 12.1N 160.3W 35 KT 40 MPH 48H 19/0000Z 11.7N 163.0W 30 KT 35 MPH 60H 19/1200Z 11.3N 165.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 20/0000Z 10.8N 168.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 21/0000Z...DISSIPATED $$ Forecaster Wroe