ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Tropical Storm Norma Discussion Number 19 NWS National Hurricane Center Miami FL EP172023 300 AM MDT Sun Oct 22 2023 Convective bursts have redeveloped over the northeastern potion of Norma's circulation, but the center remains exposed due to strong southwesterly shear. Overnight shortwave infrared satellite imagery and a couple of fortuitous ASCAT overpass showed that the center of Norma exited the east coast of the Baja California peninsula a little farther north than previously estimated. Therefore, the initial position for this advisory has been adjusted northward accordingly. Peak winds in the scatterometer passes were around 45 kt, but owing to that instrument's typical low bias the initial intensity has only been lowered to 50 kt. Since most of the Norma's circulation is forecast to remain over the Gulf of California waters today, little change in strength is expected in the short term. Once Norma moves inland over mainland Mexico, rapid weakening and dissipation over the high terrain is expected. The initial motion estimate is north-northeastward or 25 degrees at 6 kt. Most of the dynamical model guidance indicates that Norma will turn northeast, and then east-northeast during the next 12 to 24 hours, and the official forecast follows this scenario. There is fairly significant short-term spread in the guidance with the GFS taking the system more eastward, while the HWRF and ECMWF models depicted a more northeastward motion through landfall. The NHC track has been shifted significantly north of the previous advisory due to the more northward initial position, and the new track lies near the middle of the guidance envelope. It should be noted that although there is still a fair amount of uncertainty on exactly where and when the center of Norma will cross the coast of mainland Mexico, gusty winds and heavy rainfall are expected to spread onshore along much of the coast of the Mexican state of Sinaloa through tonight. Key Messages: 1. Heavy rains from Norma will continue to impact Sinaloa into Monday. Rainfall will continue to diminish across the southern portions of Baja California Sur early this morning. This rainfall will produce flash and urban flooding, along with mudslides in areas of higher terrain. 2. Tropical storm conditions will continue through this afternoon within portions of the Tropical Storm Warning area over the southern Baja California peninsula. 3. Tropical storm conditions are expected to spread onshore along portions of the west coast of mainland Mexico within the Tropical Storm Warning area through tonight. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 24.5N 109.8W 50 KT 60 MPH 12H 22/1800Z 25.0N 109.2W 50 KT 60 MPH 24H 23/0600Z 25.3N 108.5W 45 KT 50 MPH...INLAND 36H 23/1800Z 25.7N 107.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 24/0600Z...DISSIPATED $$ Forecaster Brown NNNN