textproduct: San Diego

SYNOPSIS

Inland areas will warm this weekend while coastal areas begin to cool on Sunday as onshore flow returns. Onshore flow will begin to strengthen and spread cooling inland on Monday as a low pressure system moving into California brings cooler and breezy conditions for the middle of next week, along with a slight chance of precipitation Tuesday afternoon into Wednesday morning. Cool weather and breezy onshore flow persist for the remainder of the week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

Very patchy stratus has developed over San Diego County this morning with mostly clear skies elsewhere. Expect coverage to remain sparse under weak offshore flow, clearing by mid-morning. An upper level ridge moves east across the area today as it amplifies, bringing warming across the inland areas - as much as 10 degrees warmer than yesterday in the high desert. Highs will be in the low to mid 70s along the coast, upper 70s to mid 80s for inland coastal areas and valleys, upper 50s to upper 60s in the mountains, mid to upper 70s in the high desert, and upper 80s to around 90 in the low desert. The upper level high shifts further east and continues to amplify on Sunday, continuing warming in the mountains and deserts. A return of onshore flow will spread cooling inland west of the mountains, and bring more widespread low clouds along the coast tonight into Sunday morning.

Onshore flow strengthens Monday through Wednesday as a large upper level low gradually progresses inland through California. Gradual cooling takes place through this period, with highs decreasing to around 3 to 8 degrees below normal by Wednesday. Gusty onshore winds develop over the mountains, deserts, and through the passes each afternoon and evening, peaking on Tuesday as the initial short wave passes. Wind gusts around 30-45 mph will occur along the desert mountain slopes, below the passes, and into the deserts Tuesday, with locally higher gusts below the San Gorgonio Pass.

The upper trough will also bring a slight chance of showers sometime Tuesday into Wednesday. There are still some differences in the ensembles with the exact timing of the trough. General consensus is that we'll be on the tail end of this system, with only light precipitation if any. NBM probabilities of measurable rain (at least 0.01") for the 24 hr period of 5 am Tuesday through 5 am Wednesday range from around 25% for Orange County/far west Inland Empire and the mountains to 10-15% for the remainder of the Inland Empire, high desert, and San Diego County coasts and valleys, and less than 5% in the low desert. Chances of at least 0.10" is around 20% along the south slopes of the San Bernardino Mountains and less than 10% elsewhere. A second short wave moves through sometime late Wednesday, but is currently forecast to be to dry to produce any precipitation.

Upper troughing remains across the Western US for the remainder of the week, maintaining cooler weather with high temperatures a few degrees below normal and breezy conditions in the mountains and deserts each afternoon. The marine layer will also be fairly deep during this time, but the marine inversion may be weak enough that low cloud coverage will be somewhat patchy in the coastal areas and valleys once the main trough axis passes on Wednesday.

AVIATION

180000Z...Mostly clear and VFR conditions expected region-wide through most of tonight. North to northeast winds gusting 20-35 kts through mountain passes and locally into valleys will continue to calm through about 02Z. Patchy low clouds around the coast early Saturday 10-16Z, but any cigs would be brief and isolated, based around 1000 feet MSL.

MARINE

No hazardous marine conditions are expected through Tuesday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...None.