textproduct: San Diego

SYNOPSIS

A cooling and drying trend will occur across the region into the weekend and early next week. This will be accompanied by a building marine layer with clouds returning closer to the coastal areas each night and morning. An area of high pressure may strengthen by the end of next week, nudging temperatures back above average.

..UPDATED AVIATION DISCUSSION

The 00z San Diego sounding shows a well mixed marine layer in the lowest 2,000 feet of the atmosphere with a strong inversion above it. Nighttime satellite imagery also shows this as tonight's clouds are filled in over a very broad extent, from over the coastal waters up to 20 miles inland throughout SD County and Orange County. Clouds are likely to eventually reach into the Inland Empire in the early morning hours. Communities like Riverside, Ontario and possibly San Bernardino will wake up to a low stratus deck overhead. Nighttime temperatures are generally running 2-7 degrees cooler than yesterday at this time, with morning lows expected to reach below 70 degrees across the coastal basin for the first time in over a week.

Today's temperatures will be similar to yesterday's (maybe a degree or two cooler inland) : upper 70s near the beaches, 80s in coastal areas, low 90s inland, mid-to-upper 90s in the IE and high desert and 100s in the lower deserts.

The trough over the PacNW which is bringing cooler weather to SoCal looks to move through fairly slowly, maintaining its influence through Monday. While the main trough elongates over Canada and moves eastward, the GFS and ECMWF show another lobe of cool mid- level air dropping down straight south out of British Columbia and ejecting out of the main jet stream. This lobe looks likely to become a closed upper low over NorCal and Oregon Wednesday and Thursday, which would keep temperatures close to average despite the ridge over the southeastern US intensifying and expanding westward.

WPC 500mb height clusters indicate high confidence that this ridge will eventually build Friday and Saturday, increasing temps around 5-15 degrees above average into next weekend.

Throughout the forecast period, winds remain likely onshore with a coastal eddy spinning through Wednesday and typical late afternoon south and west winds over desert slopes.

AVIATION

131130Z...Coasts/Valleys...Low clouds based 1300-1700 ft MSL have filled in the majority of the coastal basin. VIS reductions of 3-5SM in elevated inland valleys (HZ/BR) and down to 0-5SM where clouds intersect terrain in the IE and surrounding foothills. Scatter out 16-18z, though intermittent SCT-BKN cigs possible after 21z along the beaches. Low clouds will return to coastal areas 02-04z Mon and inland areas 07-09Z, with similar bases and vis reductions.

Mountains/Deserts...VFR conditions prevail through this evening with typical late afternoon S/W winds gusting 15-25 kts (up to 35 kts through the Banning Pass).

MARINE

West-northwest winds expected to gust up to 20 knots in the outer coastal waters this afternoon. Otherwise, no hazardous marine conditions are expected through Thursday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

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