textproduct: San Diego

SYNOPSIS

Some low clouds and shallow fog this morning will give way to mostly sunny skies this afternoon. A drying pattern will develop for Sunday through Tuesday, with periods of weak to moderate strength gusty Santa Ana winds. Slight warming will accompany the offshore flow for Monday and Tuesday. A low pressure system from the southwest could bring a return of precipitation for Wednesday through next Saturday.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

The low pressure system that brought widespread precipitation has moved east but we remain in the cold air behind the boundary. As the clouds moved east overnight, radiation cooling has allowed patches of shallow ground fog to form, mostly in the inland valley low spots. Scattered fair-weather cumulus clouds are moving in from the ocean and conditions are stable enough to make any light precip unlikely today. The fog will lift within the next couple of hours and the clouds will decrease throughout the day. In spite of the sunshine, temperatures today will remain well below seasonal averages except in the low deserts where they will be near average.

Dry and warmer conditions are expected for Sunday through Tuesday as high pressure builds over the west coast and a positively- tilted trough extends to the southwest over SoCal with a closed upper low forming to our southwest. Offshore flow develops on Sunday and persists through Tuesday as a sfc high moves into the Great Basin. The offshore flow gets some upper level support on Mon and Tue with northeast winds aloft. The offshore flow will likely be strongest on Tuesday, producing gusty Santa Ana winds in the mtns and lower elevations west of the mtns. Northeast to east winds gusting 35-45 mph will be possible in the favored locations. Tuesday will also be the warmest day, with high temps in the 70s west of the mtns and most areas seeing temps near or above seasonal averages. Coastal and valley areas could be as much as 7 degrees above average while the mtns and deserts will be near or just a few degrees above.

Chances for rain and mountain snow will return for Wed through next Sat as a low pressure system moves in from the Gulf of Alaska, causing the closed low to our southwest to become an open wave as it is drawn into the mean westerly flow over the Southwest US. Forecast details are still uncertain due to differences in model solutions but it's likely that we will see periods of showers between Wed and next Sat. The timing is also in question but preliminary estimates are for totals of 1"-1.5" in the coastal areas and valleys, 1"-3" in the mtns, 0.3"-0.6" in the high deserts and 0.15"-0.30" in the low deserts. The snow level will remain above 8,000 ft through Friday before lowering to around 6,500 ft on Sat.

AVIATION

271630Z...Rain has cleared the area with lingering patches of fog and a few low clouds around 1000-3000 ft MSL. Visibilities in the BR/HZ could get down to 2-6SM, locally down to 0SM, but should clear by 18-20Z. Elsewhere, VFR with some lingering 3000-5000ft MSL clouds across San Diego County into tonight. Offshore winds pick up after 15z Sunday, with gusty winds up to 25-30kts for coastal slopes of the mountains and into the valleys. Higher gusts through mountain passes with mod up/downdrafts near mountain peaks. Strong winds prevail into Monday.

MARINE

Northwest winds gusting near 20 kts will gradually decrease this afternoon. Otherwise, no hazardous marine weather expected through Thursday.

BEACHES

Westerly swell (250-270 degrees) producing surf heights 5 to 8 feet this morning and a High Surf Advisory remains in effect. Surf will begin to subside this evening and into Sunday.

SKYWARN

Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.

SGX WATCHES/WARNINGS/ADVISORIES

CA...High Surf Advisory will expire at 11 AM PST this morning for Orange County Coastal Areas-San Diego County Coastal Areas.

PZ...None.