ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM HURRICANE SIMON DISCUSSION NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014 200 PM PDT SUN OCT 05 2014 A NOAA Hurricane Hunter aircraft investigating Simon has found that the cyclone's maximum winds continue to decrease quickly. The plane measured maximum 700-mb flight-level winds of 73 kt and surface-based SFMR winds as high as 58 kt in the northeastern quadrant. Based on the aircraft data, the initial intensity is lowered to 65 kt, which could be generous. UW-CIMSS analyses and the SHIPS output indicate that southwesterly shear has increased to about 20 kt, and satellite imagery suggests that Simon's circulation is beginning to decouple. With the cyclone expected to remain over 24-25C water and in a highly sheared environment during the next few days, continued rapid weakening is anticipated. The updated NHC forecast is lower than the previous forecast mainly due to the adjusted initial intensity, and Simon is likely to become a tropical depression in 36 hours and a remnant low by 48 hours, before it reaches the Baja California peninsula. Forecast fields from the global models indicate that the cyclone will have dissipated over northwestern Mexico by day 4, which is indicated in the official forecast. Simon has turned north-northwestward with an initial motion of 330/8 kt. The hurricane is currently moving around the western periphery of a mid-level high centered near the west coast of Mexico, and it should turn northward and then northeastward around this feature during the next 48-72 hours. The model guidance is in relatively good agreement on the future track of Simon, but there continues to be disagreement on how fast Simon or its remnants reach the Baja California peninsula. For example, the GFS and ECMWF solutions are about 24 hours apart on when they bring the center of Simon to the coast. The updated NHC track forecast is a little faster than the previous one after 24 hours but is relatively close to the multi-model consensus TVCE. Even if Simon or its remnant circulation does not make it across the rugged terrain of the Baja California peninsula, deep moisture associated with the cyclone is expected to spread across the northern Baja California peninsula, northwestern Mexico, and into the U.S. Desert Southwest, which could trigger heavy rains in those regions in a few days. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 23.4N 117.5W 65 KT 75 MPH 12H 06/0600Z 24.2N 117.7W 50 KT 60 MPH 24H 06/1800Z 25.2N 117.5W 40 KT 45 MPH 36H 07/0600Z 26.2N 117.1W 30 KT 35 MPH 48H 07/1800Z 27.5N 116.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 08/1800Z 30.0N 114.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 09/1800Z...DISSIPATED $$ Forecaster Berg NNNN