textproduct: San Diego

SYNOPSIS

Areas of low clouds and locally dense fog will continue for coastal areas into this morning. Onshore flow will strengthen for this afternoon and evening with west to northwest winds for the San Bernardino County mountains and deserts gusting to 35 to 45 mph. For Thursday, stronger high pressure aloft will bring warming of 4 to 8 degrees for the coast and valleys with high temperatures for the inland valleys and lower coastal slopes of the mountains around 20 degrees above average. Onshore flow will spread cooling inland for Friday and Saturday with not much change for Sunday and Monday. An approaching low pressure system from the west will bring increasing chances for precipitation beginning Tuesday with the greatest chances for heavier precipitation for Christmas Eve and Christmas.

SHORT TERM (Today through Friday)

A strong shallow marine inversion remains in place across southern California coastal areas early this morning with satellite imagery and surface reports showing widespread low clouds and locally dense fog over the coastal waters and coastal areas with the lowest visibilities near higher coastal terrain into the far western valleys. Less coverage of low clouds is expected for the following two nights with a greater return for the weekend.

Onshore flow will strengthen for this afternoon and evening with west to northwest winds for the San Bernardino County mountains and deserts gusting to 35 to 45 mph. High temperatures today for most areas will be within a few degrees of those on Tuesday with the coast and valleys around 4 to 8 degrees warmer on Thursday as high pressure aloft strengthens. Several daily high temperature records could be tied or broken on Thursday, mainly for mountains, inland valleys, and lower deserts and well as several record warm low temperatures for early Friday.

Weak onshore flow will begin to spread cooling inland on Friday. High temperatures on Thursday will be around 20 degrees above average for the inland valleys and lower coastal slopes of the mountains with high temperatures ranging from the lower to mid 70s for the coast to the lower to mid 80s for the valleys and for the lower deserts.

LONG TERM (Saturday through Tuesday)

Onshore flow will continue to spread cooling inland on Saturday with high temperatures a few to around 5 degrees cooler than Friday, but with high temperatures still as much as 15 to 20 degrees above average for the high desert. High temperatures on Saturday will range from the mid to upper 60s near the coast to the 70s for the Inland Empire with the lower deserts in the upper 70s to mid 80s. Not much change is expected for Sunday and Monday. Night and morning coastal low clouds will spread inland to the far western valleys at times with increasing mid and high clouds across southern California by Sunday and Monday.

For the middle and latter part of next week, a low pressure system from the west with a feed of subtropical moisture will bring increasing chances for precipitation with the greatest chances for locally heavy precipitation on Wednesday and Thursday, Christmas Eve into Christmas. For Lytle Creek, one of the typically wetter locations on the coastal slopes of the San Gabriel Mountains just to the west of the Cajon Pass, the deterministic NBM has around 6.5 inches of rainfall for Tuesday through Thursday with the chance for one inch or more of rainfall for Wednesday morning through Wednesday night of 50 percent with a 2 percent chance for 6 inches or more. The deterministic NBM has snow levels of 7000 feet or higher for Wednesday and Thursday.

AVIATION

171030Z...Coast/Western Valleys...Low clouds based 100-300 feet MSL, tops to 900 feet, and fog with vis 0-3SM will continue this morning. Fog will lift and clear 16-20Z, last around KSNA. Patchy SCT-BKN clouds and vis 4-6SM in HZ to linger at the immediate coast throughout the day. Low clouds and fog return 00-02Z with similar bases and vis, but then become patchier with reduced coverage overnight into Thursday.

Otherwise...VFR conditions today and tonight. SCT-BKN high clouds through 17Z, then mostly clear.

MARINE

Areas of fog with very low visibility will continue this morning. A Marine Weather Statement contains more details. Otherwise, no additional hazardous marine conditions are expected through Sunday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Dense Fog Advisory until 10 AM PST this morning for Orange County Coastal Areas-Orange County Inland Areas-San Diego County Coastal Areas.

PZ...None.