585 WTPZ42 KNHC 071433 TCDEP2 Hurricane Olivia Discussion Number 28 NWS National Hurricane Center Miami FL EP172018 800 AM PDT Fri Sep 07 2018 Although Olivia is still a major hurricane, the cloud tops have warmed some over the past several hours and the eye is not quite as distinct as it was overnight. All of the satellite intensity estimates have decreased this cycle, and the initial intensity is lowered to 100 kt using that data. Satellite data indicate that Olivia is an annular hurricane with a well organized inner core, but with a lack of outer banding features. The hurricane is moving west-northwestward at 14 kt. The track forecast philosophy appears fairly straightforward. Olivia is expected to move westward to west-northwestward during the next few days as it remains steered by a subtropical ridge to its north. By the end of the forecast period, a turn to the west-southwest is expected as ridging builds to the northwest of the cyclone. The NHC track forecast remains near the middle of the guidance envelope, in best agreement with the consensus aids. Based on this forecast, Olivia is expected to cross into the central Pacific basin by late Saturday. Olivia is over cool 25-26 deg C waters, and it will remain over these waters during the next several days. These marginal SSTs combined with drier air should cause a slow weakening trend through the forecast period. However, as mentioned in previous discussions, research has proven that annular hurricanes like Olivia weaken slower than normal in these types of conditions. Therefore, the NHC intensity forecast shows a slower rate of weakening than the IVCN and HCCA models. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 20.1N 132.5W 100 KT 115 MPH 12H 08/0000Z 20.7N 134.5W 90 KT 105 MPH 24H 08/1200Z 21.3N 137.0W 80 KT 90 MPH 36H 09/0000Z 21.7N 139.7W 75 KT 85 MPH 48H 09/1200Z 22.0N 142.3W 70 KT 80 MPH 72H 10/1200Z 22.3N 146.9W 65 KT 75 MPH 96H 11/1200Z 22.0N 150.5W 60 KT 70 MPH 120H 12/1200Z 21.0N 155.0W 55 KT 65 MPH $$ Forecaster Cangialosi