textproduct: San Diego

SYNOPSIS

Temperatures remain below normal until Wednesday with a deep marine layer and perhaps morning drizzle early week. Warmer weather returns for the end of next week as high pressure builds.

..UPDATED AVIATION DISCUSSION

The 00z sounding Saturday afternoon shows a well mixed marine boundary layer, around 2500 feet deep with an inversion up to 5,000 feet and very dry air within and above it. Patchy low clouds are expected to fill over the lowlands of San Diego and Orange Counties as well as parts of the Inland Empire through this morning. The closed upper low continues to approach our region through Monday, deepening the marine layer to about 4000-5000 feet tonight into early Monday and significantly improving minimum humidities Monday afternoon across mountains (12-25% this afternoon to 25-50% Monday) and deserts (10-15% this afternoon to 18-30% Monday). With the deepening marine layer, there is a moderate chance for drizzle in the coastal basin early Monday and early Tuesday.

Monday will also likely be the coolest and breeziest day of the week as the main trough axis passes through the region. W/SW winds will be slightly elevated Monday afternoon and evening over desert slopes, gusting 20-35 mph and higher through the Banning Pass. Temperatures will likely struggle to reach the 80s across the Coastal Basin with perhaps a few low-80s in the IE while low desert temperatures are likely (80% chance) to remain below 100F both Monday AND Tuesday.

As the closed low departs the region, the longwave background ridge across the Southern US replaces the low and fills in over SoCal, immediately spiking the temperatures back to near average for inland areas for Wednesday, a jump of nearly 8-12F. That corresponds to highs within a few degrees of 80 at the coast, upper 80s inland, mid-90s in the IE and low-100s in the lower deserts Wednesday through Friday.

At this time, both the ECMWF and GFS are in agreement that a trough will move through NorCal and the PNW next weekend, though it remains uncertain how much it will have an influence on temperatures in SoCal.

AVIATION

201200Z...Coast/Valleys...Low clouds currently covering much of the coastal basin will begin to scatter back toward the coast after 16Z. Confidence increasing that coastal TAF sites in San Diego County will see intermittent cigs through the afternoon hours; better chance of longer scatter out at KSNA.

BKN high clouds AOA 20K ft becoming more scattered into the afternoon. Low clouds with higher bases returning 01-04Z Mon along the coast near 1800-2800ft MSL. Moderate to high confidence in low clouds filling the entire coastal basin early Monday morning with scatter out time slightly later than today for inland valleys.

Mountains/Deserts...VFR conditions through Sunday. BKN high clouds AOA 20000 ft MSL becoming SCT to FEW in the afternoon and overnight.

MARINE

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.