356 WTPA43 PHFO 160243 TCDCP3 Tropical Storm Greg Discussion Number 9 NWS Central Pacific Hurricane Center Honolulu HI EP082023 500 PM HST Tue Aug 15 2023 Deep convection around Tropical Storm Greg has been pulsing through the day, and a partially exposed low-level circulation center can be discerned through a thin veil of mid-level clouds on visible imagery this afternoon. Though light, southeasterly vertical wind shear is affecting the tropical storm, and fix agencies came in with a wide range of intensity estimates, from 2.5 out of SAB, to 3.0 at HFO, and 3.5 from JTWC. The current intensity from CIMSS ADT was recently 47 kt, though that estimate was elevated due to deep convection that had flared late this morning. Given the lack of substantial improvement in the satellite presentation and pulsing nature of the deep convection, a blend of these inputs supports holding the intensity at 45 kt for this advisory. The initial motion for this advisory is 280/12 kt. Greg appears to be starting the anticipated turn to the west-northwest toward a weakness aloft in the deep ridge north of the tropical cyclone. A general forward motion toward the west-northwest is expected tonight and much of Wednesday. Confidence is high that Greg will turn toward the west Wednesday night and Thursday as the ridge aloft begins to strengthen, causing Greg to pass several hundred miles south of Hawaii. A turn toward the west-southwest is forecast Thursday night and Friday as the weakening tropical cyclone is steered by the deep ridge to the north. The official forecast track is essentially an update of the prior advisory and lies near TVCE in the middle of a relatively clustered guidance envelope. The greatest chance for any additional strengthening will be in the short term, when vertical wind shear will remain light and the SST will hold around 28C. The guidance continues to be split into two camps. The statistical models are showing slight intensification over the next day or so followed by little change for several days. Conversely, the dynamical models show little to no short term intensification, followed by steady weakening through the next four days, possibly due to drier air aloft disrupting Greg and slightly cooler SST along the forecast track. The updated intensity forecast allows for some short term strengthening into Wednesday, followed by steady weakening as depicted by the bulk of the dynamical guidance, with Greg becoming post-tropical on Saturday. FORECAST POSITIONS AND MAX WINDS INIT 16/0300Z 11.5N 148.3W 45 KT 50 MPH 12H 16/1200Z 11.8N 150.2W 50 KT 60 MPH 24H 17/0000Z 12.2N 152.6W 50 KT 60 MPH 36H 17/1200Z 12.5N 155.1W 45 KT 50 MPH 48H 18/0000Z 12.3N 157.6W 40 KT 45 MPH 60H 18/1200Z 12.0N 160.2W 35 KT 40 MPH 72H 19/0000Z 11.7N 162.9W 30 KT 35 MPH 96H 20/0000Z 10.8N 168.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 21/0000Z...DISSIPATED $$ Forecaster Wroe