Isolated light showers will continue into Saturday for the mountains westward. Dry weather with a gradual warming trend is expected for Sunday through Friday. Weak to locally moderate Santa Ana winds develop for late Saturday night through Monday afternoon mostly gusting to 45 mph or less. Weaker offshore flow will persist Tuesday and Wednesday. Lower confidence in the weather pattern late in the week with some ensemble members showing precipitation, though the majority remain warm and dry.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Evening update, Water vapor imagery shows the upper level low approaching the central Baja California coast. Scattered showers developed over inland San Diego County earlier this afternoon but have since dissipated. Another short wave on the back side of the upper trough over the Great Basin is currently digging south through California. This will provide another burst of lift, and with relatively deep moisture (up to 700 mb) still in place, should be enough to produce drizzle or light showers through Saturday afternoon, generally for Orange and San Diego Counties. While the snow level will finally lower to around 6,500-7,000 ft tonight, mountain communities at these elevations will be mostly dry, so don't expect much more than the occasional flurry at best.
Once this short wave passes late Saturday and surface high pressure settles over the Great Basin, there will be a quick transition to offshore flow for drier weather beginning Sunday. On Saturday, highs will still be around 3 to 5 degrees below normal. Areas west of the mountains will warm to around normal on Sunday, but the mountains and deserts remain slightly below normal as cool air is ushered in from the north.
Previous discussion, The first pulse of wind arrives Saturday night and remains elevated through Sunday morning. These northeast winds could bring gusts up to 50 mph out of San Bernardino County foothills, Cajon Pass and Santa Ana Mountains. Winds relax a bit Sunday afternoon, then a second weaker pulse brings elevated east winds into the San Diego and Riverside County foothills, gusting to 40 mph through Monday. Relative humidity will drop quickly for inland areas as the winds arrive - as low as 10% in certain inland areas.
Medium range models show high confidence for a ridge to re-build over the mountain West, with a center axis along the Nevada-Utah border on Tuesday, then flattening out late week. High temperatures will remain at or slightly average, in the upper 60s and low 70s throughout the coastal basin with passing high clouds moving through. Weak offshore winds continue through the week, keeping relative humidity low for inland areas, while the coast experiences weak onshore flow. Increasing cloud cover and slightly cooler temperatures may be in store for Thursday and Friday as 20% of WPC model ensemble clusters show a closed low developing in the Pacific and moving through the West Coast.
240330z. Coasts/Valleys, Various cloud layers with one deck around 1500ft MSL, one around 3000-4000ft MSL, and another deck around 9000-10,000ft MSL. These conditions will generally prevail through 18z, with valleys and inland areas experiencing some reduced VIS down to 2-5SM between 10-18z. Iso -SHRA possible through Saturday morning for the coastal sites, but shouldn't be impactful. Low clouds will scatter out by 19z for coastal sites with FEW-SCT AOA 10,000ft MSL prevailing thereafter. Clearing of the low clouds for inland areas may occur a bit slower, closer to 20-22z. Offshore flow returns Saturday night, likely to prevent any low clouds from redeveloping/impacting any TAF sites through Sunday morning. LLWS into the IE possible, generally after 05z.
.Mountains/Deserts, SCT-BKN clouds around 10,000ft MSL and VFR conditions expected through Saturday afternoon, especially in San Diego County. BLDU possible late Saturday night into Sunday morning with gustier easterly winds. Wind through the mountain passes may exceed 30kts at times. Mod up/downdrafts near the mountains after 03z Sun.
No hazardous marine conditions are expected through Wednesday.
Ca, None. PZ, None.
