High pressure will continue to dominate the region over the next week, keeping high temperatures well above normal with minor day to day changes. The marine layer remains very shallow, leading to low clouds and fog near the coast, where the fog may be locally dense over the next couple of nights/mornings.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Satellite at 9 PM was showing areas of high clouds moving across the area, with ground observations indicating areas of low clouds and fog at the coast and portions of the western valleys. Areas of fog are restricting visibility down to 0.5 mile in some locations. Patchy dense fog is expected into Sunday morning with the highest chances for dense fog are near higher coastal terrain and in the western portions of the valleys. Highs on Sunday will still be about 5 degrees above average near the coast, and 10 to near 20 degrees above average for areas further inland.
From Previous Discussion Issued at 2 PM December 13,
Monday and Tuesday,
The shortwave trough to our east will tighten the surface offshore gradient some for Monday afternoon, with weak offshore winds expected, primarily restricted to the main mountain passes. Strongest wind gusts of 25-30 mph possible in these areas. The weak offshore flow will also help clear the marine layer out earlier Monday morning and allow temperatures to warm back up to 15-20 degrees above normal. Onshore flow resumes Tuesday but a meager marine layer Tuesday morning keeps afternoon temperatures similarly above normal as Monday's.
Wednesday through Late Week,
Ensemble clusters continue to favor a generally zonal upper level flow with broad ridging in place through some clusters feature slightly stronger ridging. Regardless, this pattern will keep temperatures slightly above normal, albeit less anomalous than Monday/Tuesday, with no precipitation chances in sight. Higher elevations, particularly the High Deserts could see elevated onshore flow if the ridging isn't as strong.
140330z, Coast/Valleys, Low clouds and FG have pushed into San Diego County and will continue to spread both east and north into Orange County. Clouds may filter up to 10 miles inland by 10z. Bases are currently 700-900ft MSL and will fall closer to 400-700ft MSL by 06-10z. VIS 2-6SM for most locations but periods of 1/4SM-1SM possible, especially for coastal terrain and valleys, primarily after 10z. Clearing will occur for much of San Diego County 18-20z, 20-21z for Orange County, with stratus lingering at certain beaches beyond this point. Low clouds with similar bases push inland again as early as 00-02z Mon for SD County, and after 04z for Orange County.
Mountains/Deserts, Clear skies and VFR conditions expected through the TAF period.
Patchy low clouds with visibility generally above 1 nautical mile will continue into early Sunday afternoon. Otherwise, no hazardous marine conditions are expected through Thursday.
Ca, None. PZ, None.
