Weak high pressure over the region will bring warmer weather with high temperatures up to 10 degrees above normal in the inland areas this afternoon. An area of low pressure off the coast will move inland Monday through Tuesday. This will bring cooler and breezier weather by Sunday, with chances of light rain showers for Monday and Tuesday from the mountains to the coast. Drier weather with a warming trend is expected for the rest of the week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Weak high pressure will hang on one more day today with warmer temperatures as clouds clear out toward the coast. A closed low is seen offshore. This will bring changes to our weather by Sunday through Tuesday. Cooling will begin to spread inland on Sunday as winds across the mountains and deserts increase from the west. High temperatures will cool around 5 to 10 degrees away from the coast. Peak winds for Sunday afternoon and night across the mountains and deserts will range from 25-40 MPH. Winds will max out on Monday afternoon and night, mainly increasing for areas of the mountains with peak gusts near 60 mph at times through passes. This will lead to increased risk for drivers of high profile vehicles, especially along Interstate 10.
Though PWAT values increase slightly as the system moves closer, it does not look to have much moisture. As the low draws closer Sunday and Monday, the marine layer will continue to deepen. This may lead to some drizzle / light showers across western San Diego County by Sunday morning. The best chance of light rainfall will be Monday evening into Tuesday morning for places along and west of the mountains. Areas of San Diego County have the best chance to see rainfall, especially along the coastal slopes. Whatever (if any) falls will be light, mainly under one tenth of an inch. This weather system will also bring much cooler temperatures by Monday and Tuesday with highs 5 to 15 degrees below normal. Highs in the 60s will prevail for areas west of the mountains into the high desert with 70s to near 80 degrees across the lower deserts. Low temperatures will also be quite chilly with lows getting down into the 20s and 30s above 5,000 feet.
Ensemble models are in fair agreement of this low moving out of the region by Wednesday, where a ridge will take its place. This will bring drier and warmer weather to the region. Inland valleys are expected to warm about 7-12 degrees from Tuesday to Wednesday and another 10 degrees by Thursday, putting areas of the Inland Empire near 90 degrees. The high looks to expand across the desert southwest, leading to continued warm and dry weather as we head into the middle part of the month.
021600z. Coast/Valleys, Low clouds based 1400-1800 ft MSL with local VIS reductions 2-6SM. Vis improves (and bases lift) 15-16z and clouds scatter out inland 15-17z. Scatter out at the coast 17-19z, though some patchy low clouds to linger into the afternoon. Low clouds redevelop Saturday evening (02-04z Sun) with similar bases initially, rising above 2000 ft MSL in areas progressively throughout the night.
.Mountains/Deserts, VFR conditions expected through the period with SCT-BKN high clouds AOA 20 kft after 18z Sat.
No hazardous marine conditions are expected through Wednesday.
Ca, None. PZ, None.
