000 WTPZ41 KNHC 070301 TCDEP1 Hurricane Sergio Discussion Number 31 NWS National Hurricane Center Miami FL EP212018 800 PM PDT Sat Oct 06 2018 Little overall change has been noted in Sergio's satellite presentation the past several hours other than cloud tops have warmed slightly. The 30-nmi-wide eye remains quite distinct and outflow is still very impressive in all quadrants. However, he warming tops have resulted in slightly lower satellite intensity estimates from all agencies, so the initial intensity has been lowered to 105 kt for this advisory. Sergio is lumbering along toward the west, or 270/06 kt. There is no significant change to the previous forecast track or reasoning. Sergio should continue to move slowly westward around the southwestern periphery of a weak deep-layer ridge for the next day or so. By early next week, a strong trough is forecast to dig southward off the coasts of California and Baja California, which will erode the ridge and cause Sergio to make a sharp northeastward turn and accelerate throughout the forecast period. The latest NHC track guidance remains in good agreement on this developing steering flow pattern, and there is very little cross-track spread in the models. The speed differences noted in the previous discussion have decreased on this forecast cycle, so only minor tweaks had to be made to the previous advisory track. The new forecast track lies close the previous one and near a blend of the various consensus track models. Ocean temperatures beneath the cyclone are forecast to decrease over the next few days due to cold upwelling beneath the hurricane, so gradual weakening is expected for the next 3 days. After that, more rapid weakening is forecast due to increasing southwesterly vertical wind shear ahead of a a deep-layer trough. The NHC intensity forecast is very similar to the previous advisory and the IVCN consensus model. FORECAST POSITIONS AND MAX WINDS INIT 07/0300Z 14.5N 125.4W 105 KT 120 MPH 12H 07/1200Z 14.5N 126.4W 100 KT 115 MPH 24H 08/0000Z 14.8N 127.2W 95 KT 110 MPH 36H 08/1200Z 15.4N 127.6W 90 KT 105 MPH 48H 09/0000Z 16.1N 127.4W 85 KT 100 MPH 72H 10/0000Z 18.0N 124.9W 75 KT 85 MPH 96H 11/0000Z 20.9N 120.6W 60 KT 70 MPH 120H 12/0000Z 25.6N 115.1W 45 KT 50 MPH $$ Forecaster Stewart