Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
182 FXUS66 KSGX 161639 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 939 AM PDT Mon Sep 16 2024 .SYNOPSIS... Cooler and windier today with isolated light showers this morning. Dry conditions with a few degrees of warming and weaker winds are expected Tuesday. For Wednesday evening into Thursday, unsettled weather is expected again with additional chances of precipitation. Drier and warmer conditions expected Friday through the weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A few isolated showers have been observed on radar as of 9 AM this morning. Rainfall accumulations so far have been light and mostly under 0.10 of an inch. The shower activity so far has been confined to the higher terrain, locally along the coast and in the valleys. The isolated shower activity is expected to diminish into the afternoon. For early Tuesday, light showers or drizzle are possible mainly in San Diego County but coverage will mostly be confined to higher terrain. Periods of gusty winds are expected this afternoon and evening. Strongest winds will be through passes and into the deserts. Peak gusts of 35 to 45 mph are expected over the mountain ridge tops, desert slopes, and High Desert. Gusts 45 to 55 mph are expected in the San Diego deserts with gusts up to 65 mph possible through the Cajon Pass. Dry conditions are expected for much of the day Tuesday (only exception may be Tuesday morning) into Wednesday evening. A few degrees of warming is expected Tuesday west of the mountains and in the low desert with 5 to 10 degrees of warming in the mountains and High Desert. Winds will be weaker as well. On Wednesday an upper level low will begin to dig south along the coast of the Pacific Northwest. By Wednesday night or early Thursday morning the low will begin to move inland across Central and Southern California. This system is expected to bring additional chances of precipitation to Southern California as early as late Wednesday night. This system looks like a warmer one, so there will only be minor fluctuations in temperatures for Tuesday through Thursday. Current ensemble guidance does not have a very significant uptick in winds with ensembles indicating winds may be weaker than today. NBM chances of wind gusts greater than 45 mph are 35 to 45 percent for Wednesday and Thursday afternoon and evenings and confined to wind prone passes, like the San Gorgonio Pass. Current high resolution model guidance is showing the potential for rainfall totals more than what we`re seeing today for Thursday but likely under 0.50 inch total for most locations. For Friday through next weekend, the low pressure system over the southwest states will weaken and move east with high pressure over the eastern Pacific moving across California. High temperatures will be several degrees warmer for Friday and Saturday with high temperatures for next Sunday warming to a few degrees above average for the deserts to around 5 degrees above average for the coast and valleys, mostly in the 90s for the inland valleys and 100 to 105 for the lower deserts. && .AVIATION... 161530Z...Low clouds with bases varying 2000-3500 feet MSL and tops to 5200 feet will continue to shroud the coast to mountains, including higher terrain obscured in BR. -RA or -DZ likely anywhere, but most likely in foothills under these clouds through 18Z. When/where this precip occurs, vis could be reduced 0-5SM and cigs drop to 1500 feet MSL. Partial scatter out more likely at coast starting at 19Z and working inland, probably not scattering out much if at all in far inland valleys. Low clouds and fog to fill in the entire coastal basin again tonight into Tuesday, but with bases/tops a few hundred feet lower. Confidence in late afternoon clearing at KSAN per the TAF is MDT-HIGH. Smoke from the Line, Bridge and Airport fires will continue to reduce VIS in mountains, with hazy conditions over the Inland Empire and parts of the deserts. West-northwest winds will gust 40-50 knots through mountain passes, continuing into tonight. Local moderate up/downdrafts in lee (east) of mountain ridges. && .MARINE... No hazardous marine conditions are expected through Friday. Although, northwest gusts around 20 knots are expected in the outer waters this afternoon and evening and again Wednesday afternoon and evening. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory until 9 PM PDT this evening for Apple and Lucerne Valleys. Wind Advisory until midnight PDT tonight for San Diego County Deserts. Wind Advisory until midnight PDT tonight for San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC...CO AVIATION/MARINE...Small