ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Hurricane Genevieve Discussion Number 9 NWS National Hurricane Center Miami FL EP122020 900 AM MDT Tue Aug 18 2020 Since the issuance of the last advisory, Genevieve has continued to rapidly intensify. The major hurricane has a very well-defined and clear eye and microwave imagery as recent as 12Z did not show any indication of a secondary eyewall. Objective intensity estimates from the UW-CIMSS SATCON were as high as 124 kt earlier this morning, but subjective Dvorak estimates at 12Z were a little lower due to the formation of a small break in the cold cloud tops surrounding Genevieve's eye. Even then, a blend of all available intensity estimates still supports an intensity of 115 kt for this advisory. Additional rapid strengthening is possible for at least the next 12 h given the current structure of the hurricane and the extremely favorable environment it is moving through. The NHC forecast is well above the guidance for the next 24 h out of respect for that possibility. It is worth noting that eyewall replacement cycles are generally poorly forecast and the onset of one could bring an abrupt halt to Genevieve's intensification. By the time Genevieve nears the Baja California peninsula on late Wednesday, rapid weakening is expected as the system moves over cooler waters and encounters an increase in southwesterly shear associated with an upper-level trough to the northwest. Upwelling from the hurricane's own wind field and decreasing forward speed could also bring about weakening. By the end of the weak Genevieve will likely weaken to a tropical storm and then become a remnant low. The hurricane is moving slightly slower toward the northwest and a further decrease in forward speed is anticipated for the next day or two. There was no substantial change made to the NHC track forecast, and Genevieve is still predicted to be steered just west of the Baja California peninsula by a deep-layer ridge centered over the southwestern U.S. The track guidance remains tightly clustered, so confidence in the forecast remains fairly high. Key Messages: 1. The center of Genevieve is forecast to move just west of the Baja California peninsula, but it is still expected to cause tropical storm conditions across portions of southern Baja California Sur. These conditions are expected to begin Wednesday afternoon and could spread northwestward through Thursday. 2. Large swells generated by Genevieve are affecting portions of the coast of southern Mexico and will spread northward along the coast of Mexico to the Baja California peninsula by Wednesday. FORECAST POSITIONS AND MAX WINDS INIT 18/1500Z 18.0N 108.0W 115 KT 130 MPH 12H 19/0000Z 19.0N 109.3W 130 KT 150 MPH 24H 19/1200Z 20.2N 110.4W 130 KT 150 MPH 36H 20/0000Z 21.3N 111.3W 120 KT 140 MPH 48H 20/1200Z 22.2N 112.3W 105 KT 120 MPH 60H 21/0000Z 23.2N 113.5W 90 KT 105 MPH 72H 21/1200Z 24.1N 115.0W 75 KT 85 MPH 96H 22/1200Z 26.3N 118.1W 50 KT 60 MPH 120H 23/1200Z 28.7N 121.4W 35 KT 40 MPH...POST-TROPICAL $$ Forecaster Zelinsky NNNN