textproduct: San Diego

SYNOPSIS

High pressure and weak offshore flow will continue to bring fair weather and above normal temperatures through Friday, with cooler weather this weekend. Coastal low clouds and fog will continue each night and morning, but less inland coverage through Thursday and more coverage Friday through the weekend.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

At 9 PM, low clouds and areas of fog had developed along much of San Diego county coast and was inching into portions of Orange County. Fog was taking visibilities down to anywhere from 0.25 mile in the western valleys to 4 to 6 miles near the coast. Weak offshore flow may keep the fog from becoming widespread overnight, but areas of fog that are locally dense are expected to be present Tuesday morning.

From Previous Discussion Issued at 2 PM December 15...

Weak offshore winds will result in some patchiness to the cloud coverage overnight, and the marine layer will back off to the beaches earlier than today, around mid Tuesday morning. Lingering foggy conditions for the beaches and parts of Orange County looks likely again through later morning Tuesday, though.

Locally breezy offshore winds in the coastal foothills and south of the Cajon Pass/west of the Banning/Gorgonio Pass will continue through Tuesday morning. Peak gusts are generally 20-30 mph, with occasional/local gusts around 40 mph. Another warm day is in store for Tuesday afternoon as the east Pacific high pressure edges into the area, with high temperatures 1-5 degrees warmer than today. With persistent high pressure aloft, the marine layer will continue to be shallow and limited to coastal areas Tues-Wed. Onshore flow resumes Wednesday, which will cool things down a tad from Tuesday for most areas west of the mountains.

LONG TERM

Temperatures continue to oscillate for the late week as conditions flip from weak onshore to weak offshore again and ridging amplifies slightly Thursday, which will be another warm day similar to Tuesday, with high temperatures as much as 10-20 degrees above average for mid December. The flow becomes onshore again Friday into the weekend as the ridge flattens out into zonal flow over most of the western U.S. This will lead to a gradual cooling trend Friday through the weekend, though temperatures will still remain above average, which seems to be the song of the season recently.

Temperatures may rise again early next week as a ridge builds over a large part of the southern U.S. Towards mid to late week a trough is likely to move south down the west coast, giving us a chance for precipitation towards Christmas Eve/Christmas, though details are fuzzy this far out.

AVIATION

160430Z...Coast...Low clouds and fog currently impacting KSAN and KCRQ. Impacts expected within the next 2 hours at KSNA. Bases 400- 600 ft MSL will lower overnight but low clouds and fog are unlikely to spread more than 5-10 miles inland. Coverage will likely be a little less than last night but periods of VIS below 1SM are likely at coastal TAF sites. Low clouds and fog expected to clear out of San Diego County coastal areas 13-15Z and Orange County coastal areas 15-17Z.

Valleys/Mountains/Deserts...Clear skies with unrestricted VIS through Tuesday.

MARINE

Areas of fog will return to coastal waters this evening and last through Tuesday morning. Intermittent visibility reductions below 1 nautical mile expected. Otherwise, no hazardous marine conditions are expected through Friday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

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