Slow warming will continue for the inland areas through mid week, bringing high temperatures to 4 to 10 degrees above average for Wednesday and Thursday. The coast and valleys will cool a few degrees on Tuesday, then warm a few degrees for Wednesday and Thursday, with night and morning coastal low clouds spreading into portions of the valleys late each night. A low pressure system moving into the western states will bring a cooling trend for Friday through the weekend, with high temperatures for next Sunday falling to a few to about 10 degrees below average by Sunday.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Predominately zonal flow aloft today has resulted in what some may call Chamber of Commerce weather, i.e. Sunny and warm. Weak troughing moving into the western part of the region late tonight will lead to the marine layer moving in earlier this evening, likely moving into the immediate coast along San Diego County 5-6 PM. Clouds will be around 2000-2500 feet above the ground+ and will move a little farther inland than this morning, including into parts of the Inland Empire. These will clear out, similar to this morning, mid to late morning Tuesday. The weak trough will also lead to a few degrees of cooling between this afternoon's highs and Tuesday's highs outside of the mountains and deserts, where it will warm a degree or two for tomorrow.
This trough will swiftly move southwest out of the region as a weak ridge moves in from the east mid-week. Temperatures will warm a tad over the region for Wednesday and Thursday to 4-10 degrees above average for inland areas, and the marine layer will get a bit shallower (travel less far inland overnight). Broad, stronger troughing moving into the western U.S. Will lead to a cooling trend Friday through at least Sunday, though persisting model differences in strength and position lead to a bit of uncertainty regarding degree and longevity of the cooling. The current forecast is for high temperatures 5-10 below average inland for Sunday. Marine layer clouds will deepen again, reaching farther inland to cover most of the valleys over the weekend.
012345z, Coast/Valleys, Patchy low clouds over nearshore waters currently will begin to spread into coastal San Diego County over the next few hours. Clouds will quickly spread into Orange County and western valleys up to 10-15 miles inland by 06z Tue. Clouds spread further into portions of the Inland Empire by 12z (70% chance KONT, 40% chance KSBD). Bases 1000-1500 ft MSL may create minor vis reductions (2-6SM) for elevated inland valleys, especially the Inland Empire. Low clouds scatter toward the coast 15-18z Tue.
Mountains/Deserts, Mostly clear skies and VFR conditions expected through the period.
No hazardous marine conditions are expected through Saturday.
Ca, None. PZ, None.
