000 WTPZ41 KNHC 060845 TCDEP1 Hurricane Sergio Discussion Number 28 NWS National Hurricane Center Miami FL EP212018 200 AM PDT Sat Oct 06 2018 Sergio has changed little in structure since the last advisory. It still has a 25-30 n mi wide eye surrounded by cold convective tops, and with not much change in intensity estimates, the estimated maximum winds remain 110 kt. Sergio's intensity is not likely to change much during the next day or two, although some slight weakening is possible as the hurricane's speed slows down and it upwells some colder water from below, or due to possible internal structural changes. More definitive weakening is anticipated by days 4 and 5 due to an increase in westerly and southwesterly shear and the hurricane reaching colder waters. The NHC intensity forecast remains close to a blend of the ICON consensus and the HCCA model. However, the statistical-dynamical models remain a bit higher, and it is possible that Sergio won't lose quite as much punch during the next several days as is indicated by the official forecast. Sergio continues to dive southwestward with an initial motion of 235/7 kt. A shortwave trough swinging across the Baja California peninsula will bypass Sergio during the day, leaving a weakness in the ridge that will allow the hurricane to begin making a sharp northward and then northeastward turn during the next 24-72 hours. Another shortwave trough forecast to dig southward off the California coast will then cause Sergio to accelerate northeastward on days 4 and 5. Notable changes in this forecast update include a slightly wider turn from 24-72 hours, and more spread in the model speeds once Sergio accelerates toward the Baja California peninsula. As is usually the case in these scenarios, the ECMWF is much slower than the other models, and because of that, the new NHC forecast is a bit slower than the previous one, especially on day 5. FORECAST POSITIONS AND MAX WINDS INIT 06/0900Z 14.9N 123.5W 110 KT 125 MPH 12H 06/1800Z 14.6N 124.4W 105 KT 120 MPH 24H 07/0600Z 14.4N 125.6W 100 KT 115 MPH 36H 07/1800Z 14.7N 126.5W 95 KT 110 MPH 48H 08/0600Z 15.2N 127.0W 90 KT 105 MPH 72H 09/0600Z 16.9N 126.1W 80 KT 90 MPH 96H 10/0600Z 19.0N 123.0W 65 KT 75 MPH 120H 11/0600Z 23.0N 118.0W 55 KT 65 MPH $$ Forecaster Berg