textproduct: San Diego

SYNOPSIS

Cooler conditions through the middle of the week with periods of elevated winds over the mountains and into the deserts. Light precipitation is possible west of the mountains Tuesday evening into Wednesday, which coincides with the timing of the strongest westerly winds. Thursday will warm a few degrees. Cooler conditions likely this weekend, with periods of increased winds and potentially another round of light precipitation west of the mountains.

Updated Aviation/Marine Discussion

High temperatures today west of the mountains are expected to be a few degrees cooler than yesterday with no change or a few degrees of warming in the mountains and deserts. Additional cooling is expected through the middle of the week as a trough of low pressure influences the US West Coast. The trough of low pressure is expected to approach the West Coast Tuesday and be to our east by Wednesday evening. This low will bring widespread cloud coverage, increase winds over the mountains and deserts, and areas of light precipitation.

Southwest to west winds will begin to strengthen Tuesday afternoon, peak in strength overnight, and weaken Wednesday morning. Strongest winds will be over the mountains and into the deserts. Peak gusts of 40 to 60 mph expected, with a few isolated gusts to 65 mph on the northern slopes of the San Bernardino mountains. Winds will decrease through the day Wednesday with gusts mainly 35 to 45 mph, locally up to 55 mph through wind prone passes like the San Gorgonio Pass. Periods of light precipitation are expected Tuesday evening into early Wednesday morning. The forecast has trended drier, with the most likely place for measurable precipitation in the San Bernardino County mountains. Hourly rainfall rates are expected to be 0.10 inch or less.

Dry and warmer conditions expected on Thursday. Highs along the coast will be a few degrees warmer, with inland locations up to 7 degrees warmer than Wednesday. The temperature increase will bring conditions near to slightly above normal for this time of year. Another area of low pressure looks likely to move across the US West Coast for the upcoming weekend. While there remains some timing differences between the global models, the trough will bring another round of cooler conditions, increase in westerly winds, and potential for light precipitation.

AVIATION

210430Z...Coast/Valleys...Very patchy low clouds based 1800-2200 ft MSL have started to develop over nearshore waters and coastal San Diego County. Coverage of low clouds should remain patchy through the night with intermittent clearing at times. Patchy clouds may spread into Orange County and the southern Inland Empire after 11z Tue. Regardless, clouds clear to the coastline by 14-17z. A band of low clouds based 1500-2500 ft MSL associated with a weak front will move from west to east across the coastal basin starting around 21z Tue. ISO -SHRA may briefly create MVFR vis Tuesday evening. Clouds mostly clear out from west to east late Tuesday evening, but may linger overnight in San Diego County.

Mountains/Deserts...West to west-southwest winds will continue to gust 25-35 kts through mountain passes, along desert slopes and locally into deserts through this evening. Winds slowly diminish after 06z Tue. Winds pick up again out of the southwest on Tuesday, becoming strong after 21z. Widespread gusts 35-45 kts expected with gusts locally to 55 kts along desert slopes and through mountain passes. Winds turn westerly 00-06z Wed, but should remain strong through Tuesday night. Areas BLDU in the deserts and moderate/strong up/downdrafts in lee of mtns.

MARINE

Westerly winds will increase Wednesday afternoon with gusts 20-25 knots likely for outer coastal waters. This may generate hazardous conditions for small craft Wednesday evening into early Thursday morning. 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...Wind Advisory from 2 PM Tuesday to 7 AM PDT Wednesday for Apple and Lucerne Valleys-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.

PZ...None.