ZCZC MIATCPEP4 ALL TTAA00 KNHC DDHHMM BULLETIN Tropical Storm Hilary Advisory Number 17 NWS National Hurricane Center Miami FL EP092023 800 AM PDT Sun Aug 20 2023 ...HILARY VERY NEAR THE WEST COAST OF BAJA CALIFORNIA... ...CATASTROPHIC AND LIFE-THREATENING FLOODING LIKELY OVER BAJA CALIFORNIA AND PORTIONS OF THE SOUTHWESTERN U.S. THROUGH MONDAY... SUMMARY OF 800 AM PDT...1500 UTC...INFORMATION ---------------------------------------------- LOCATION...29.7N 115.9W ABOUT 220 MI...350 KM SSE OF SAN DIEGO CALIFORNIA MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H PRESENT MOVEMENT...NNW OR 345 DEGREES AT 25 MPH...41 KM/H MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The government of Mexico has discontinued the Hurricane Watch and downgraded the Hurricane Warning to a Tropical Storm Warning for the Baja California Peninsula. The government of Mexico has discontinued the Tropical Storm Warning south of Puerto San Andresito on the west coast and south of Loreto on the east coast of the Baja California Peninsula. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Baja California peninsula west coast from Puerto San Andresito northward * Baja California peninsula east coast from Loreto northward * Mainland Mexico north of Guaymas * California/Mexico border to Point Mugu * Catalina Island A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning. Interests elsewhere in the southwestern U.S. should monitor the progress of Hilary. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 800 AM PDT (1500 UTC), the center of Tropical Storm Hilary was located near latitude 29.7 North, longitude 115.9 West. Hilary is moving quickly toward the north-northwest near 25 mph (41 km/h). Hilary is expected to accelerate even more as it moves north-northwestward to northward during the next day or so. On the forecast track, the center of Hilary will move near or over the northern portion of the Baja California Peninsula during the next few hours, and then move across southern California this afternoon. Maximum sustained winds are near 70 mph (110 km/h) with higher gusts. Weakening is expected, but Hilary is expected to remain a tropical storm before it reaches southern California. Tropical-storm-force winds extend outward up to 240 miles (390 km) from the center. The estimated minimum central pressure is 984 mb (29.06 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Hilary can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDEP4 and WMO header WTPZ44 KNHC and on the web at hurricanes.gov/text/MIATCDEP4.shtml. RAINFALL: Hilary is expected to produce storm total rainfall amounts of 3 to 6 inches, with maximum amounts up to 10 inches, across portions of the northern Baja California Peninsula through tonight. Flash and urban flooding, locally catastrophic, is expected. Intense heavy rainfall associated with Hilary is expected across the Southwestern United States through early Monday morning. Rainfall amounts of 3 to 6 inches, with isolated maximum amounts of 10 inches, are expected across portions of southern California and southern Nevada leading to dangerous to catastrophic flooding. Across portions of Oregon and Idaho, rainfall totals of 1 to 3 inches with local maxima to 5 inches are expected through Tuesday morning, resulting in localized, some significant, flash flooding. A list of rainfall observations compiled by the NOAA Weather Prediction Center for this storm can be found at: www.wpc.ncep.noaa.gov/discussions/nfdscc4.html WIND: Tropical storm conditions are occurring within the tropical storm warning area within the Baja California Peninsula and will continue through today. Tropical storm conditions are expected to begin in southern California this afternoon. Winds could be particularly strong and gusty in and near areas of elevated terrain. Higher gusts are expected well inland and will persist even after the system becomes post-tropical. STORM SURGE: A dangerous storm surge is likely to produce coastal flooding along the western Baja California peninsula of Mexico near where the center passes the coast in areas of onshore winds, or east of the center if Hilary makes landfall. The surge will be accompanied by large and destructive waves. Coastal flooding is possible along the northern coast of the Gulf of California today through early Monday. TORNADOES: A couple tornadoes are possible through this evening over southeast California, western Arizona, southern Nevada, and far southwest Utah. SURF: Large swells generated by Hilary will affect portions of the Baja California Peninsula and southern California over the next day or so. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next intermediate advisory at 1100 AM PDT. Next complete advisory at 200 PM PDT. $$ Forecaster Cangialosi NNNN