Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
700 FXUS66 KSGX 200445 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 945 PM PDT Sun May 19 2024 .SYNOPSIS... A large-scale trough over western North America will persist through this week. Temperatures will remain below seasonal averages with gusty winds across the mountains and deserts. A closed upper level low will move across the region on Monday, which will bring the coolest and windiest conditions overall. Low clouds will continue nights and mornings, retreating back to the coast each afternoon. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... No Significant changes to the forecast this evening as the closed low off the Baja California Coast becomes incorporated into the zonal mean flow. This will transport the low as an open wave across Baja California bringing an enhanced chance of drizzle overnight as the marine layer reforms. ...Previous Discussion from 127 PM PDT Sun May 19 2024... This afternoon, the marine layer low clouds have cleared to about 25 miles offshore and much like yesterday, will return to the coast in a couple of hours then spread inland to the coastal slopes by about 5 am Monday. The marine layer will likely deepen, with enough moisture to produce patchy drizzle late tonight and early Monday morning, although accumulations are unlikely. Onshore flow continues with sfc pressure gradients 4.2 mb SAN-DAG and 6.2 mb SAN-IPL currently producing westerly winds gusting 30-40 mph and up to 55 mph in the windiest locations. From previous discussion... A closed upper low currently about 900 miles southwest of San Diego will be drawn into the mean flow and become an open wave over SoCal on Monday as a large-scale trough to the north deepens. This will bring additional cooling to the region and Monday will likely be the coolest day of the week. Temperatures will be near 5 degrees below average across the coastal areas with up to 10 degrees below average for inland areas. It will also strengthen the westerly winds, especially in the mtns and adjacent desert areas where chances are good for wind gusts over 40 mph and over 55 mph in wind-prone mountain passes. The San Gorgonio Pass will have a 70-80% chance of wind gusts exceeding 55 mph. The trough over the West Coast will continue, though not as amplified as Monday. Rising heights will lead to some warmer conditions and somewhat weaker winds over inland regions. Little day-to-day variations in temperatures, winds and marine layer clouds can be expected from Tuesday through the end of the week, where we will see slightly below average temperatures and May Gray conditions west of the mountains in the morning with general clearing toward the coast by the afternoons. As we get into next weekend, the consensus of model solutions shows the dominant trough weakening and a building ridge of high pressure centered over eastern Mexico. At this time, it seems likely that the weather over SoCal will continue to be dominated by troughing over western North America. && .AVIATION... 200400Z...Coast/Valleys...Low clouds have been delayed this evening but BKN/OVC skies with bases 1500-2300 ft MSL and tops to 2500 ft MSL will still reach most coastal airports by 07Z Mon and most valleys by 10Z. Higher terrain will be obscured at times but most VIS under the clouds will be 6+ miles with local VIS 2-4 miles in BR or -DZ 08Z-16Z Mon. Local -DZ will occur 10Z-16Z Mon. Most areas will clear 15Z-18Z Mon except for local BKN CIGs near the coast Mon afternoon. Areas of low clouds will develop mostly after 03Z Tue near the coast with similar bases. Mountains/Deserts...Clear skies with unrestricted VIS will continue through Mon evening. Areas of west winds with surface gusts 25-45 knots will continue through Mon evening, with highest winds from the mountain crests through the desert slopes and into the deserts plus through mountain passes. There is around a 20 percent chance of a 35 kt gust at TRM and PSP from 23Z Mon to 04Z Tue. Blowing dust could locally reduce VIS to 2-4 miles at times. && .MARINE... A few wind gusts could reach or slightly exceed 20 knots Monday afternoon and evening in the outer coastal waters mainly near San Clemente Island. Otherwise, no hazardous marine conditions are expected through Friday. && .BEACHES... A series of southwest swells of 2-3 ft at 16-18 seconds from 200-220 degrees will build through Monday and produce above normal surf of 3- 5 ft with locally higher sets on exposed SW facing beaches, as well as a high risk of rip currents at all beaches. A Beach Hazards Statement is in effect through Monday evening. Swell and surf will slowly lower Wednesday and Thursday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement through Monday evening for Orange County Coastal Areas-San Diego County Coastal Areas. PZ...None. && $$ PUBLIC...Suk AVIATION/MARINE/BEACHES...Maxwell