Temperatures peak today with a slight cooling for Sunday and Monday. Patchy dense fog is possible over the coastal waters and along the immediate coast Sunday night into Monday. Warmer conditions return for the middle to end of next week with additional periods of Santa Ana winds.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Widespread clear skies are being observed across the area, with locally gusty easterly winds on coastal mountain foothills and below passes. Winds will continue to weaken through the afternoon, with high temperatures today expected to peak at 15 to 20 degrees above average for inland valleys and about 10 degrees above average for the coast, deserts, and mountains. A few degrees of cooling is expected on Sunday for the coast and valleys, with more widespread cooling into Monday. Even with the aforementioned cooling, highs Sunday and Monday will remain above average for this time of year.
Onshore flow will return for Sunday into Monday as a weak shortwave trough moves through Southern California. In addition to the slightly cooler conditions, the marine layer will begin to rebuild. Local high resolution guidance is indicating a coastal eddy will develop Sunday night into Monday morning, which will increase the chances of coastal low clouds and fog developing. The marine layer is expected to remain fairly shallow with low clouds and fog staying over the waters and within a few miles of the coast. Areas of dense fog are possible.
By Tuesday, all global ensemble guidance indicates a ridge of high pressure will rebuild over the US West Coast. The upper level ridge is expected to remain over the western United States through the end of next week. This will bring another period of warm and dry weather to Southern California. Nbm chances for highs exceeding 85 degrees are currently highest on Wednesday at 60 to 70 percent for the valleys, locally up to 90 percent for portions of the Inland Empire and inland Orange County. Chances go down Thursday, due to some models indicating a slightly eastward shift of the ridge axis, but remain a 50 to 60 percent chance of exceedance. The absence of marine layer influence for the middle to end of the week will allow coastal high temperatures to rise as well.
With the upper level ridge in place over the West Coast, a surface high is expected to form over the Great Basin for the middle to end of the week. This will bring another period of Santa Ana winds. The CW3E West-WRF ensemble guidance has a 60 to 80 percent chance of a weak to moderate wind event with a 20 percent chance of a moderate to strong wind event. Current guidance indicates locations more prone to easterly/northeasterly winds will be more impacted than areas more prone to northerly winds.
311630, VFR conditions with mostly clear skies except for FEW-SCT clouds AOA 20k ft continue through the TAF period. Breezy northeasterly winds will continue in the foothills and below mountain passes and locally into adjacent valleys through about Sun 06Z, with gusts to 20-30 kts in these areas.
No hazardous marine conditions are expected through Wednesday.
Fresh northwest swell 3-5 feet at 15-17 sec will move in late Sunday night into Monday morning, likely leading to breaking waves of 5-7 feet with local sets to 8 feet on west-facing beaches Monday into early Tuesday. Additionally, morning high tides 6-6.5 feet combined with the larger surf will possibly result in minor tidal overflow/flooding for low-lying beach lots and walkways Monday morning.
Ca, None. PZ, None.
