textproduct: San Diego

SYNOPSIS

Cooler weather persists through the weekend, with a deeper, more persistent marine layer and night and morning coastal low clouds extending well inland and onto the coastal slopes of the mountains. Southwest to west winds for the mountains and deserts will gust to 40 to 50 mph through Sunday, with isolated gusts to 65 mph. Gradually warmer, dry weather with generally weak winds will follow Monday through Thursday, followed by a slight cooldown from Thursday into Friday.

SHORT TERM...Today through Monday 5/18

A broad trough over the western U.S. centered over the Great Basin is leading to our current cool, breezy weather. Current westerly gusts over the mountain desert slopes into the deserts are 30-50 mph, with gusts to 65 mph through the Banning/San Gorgonio passes. Peak gusts to 40-50 mph with isolated 65-70 mph through passes are expected through Sunday. Winds weaken slightly late tonight through Sunday morning, before strengthening again to similar levels Sunday afternoon and evening. This will lead to areas of blowing dust which could result in locally lowered visibility. Elsewhere, winds are more moderate with peak gusts generally 15-25 mph for the coasts and valleys.

Cool air brought by the trough in combination with more persistent marine layer cloud cover today are contributing to temperatures on the cooler end this afternoon, with highs near average to about 6 degrees below average widespread through the region. Sunday will be cooler than today, with high temperatures a few up to 10 degrees cooler than average. This will amount to high 60s to low 70s for the coasts and valleys, high 70s for the high desert, and 80-92 degrees for the San Diego desert and Coachella Valley. Cloud cover will continue to persist today, becoming more widespread this evening and moving to cover the entire coastal basin again overnight. Patchy areas of drizzle are possible tonight, most likely along the mountain foothills and for San Diego County. More clearing is expected Sunday, but patchy cloud cover will linger, especially towards the coast/western valleys.

As the axis of the trough continues to move to the east into the Intermountain West late Sunday into Monday, winds will turn offshore (north to northeast) in the deserts as they gradually weaken. Temperatures will start to warm for coastal and valley regions while the mountains and deserts continue to cool a few degrees.

LONG TERM...Tuesday 5/19 through Saturday 5/23

While broad troughing lingers over the western U.S., mid-level heights will build over the region, resulting in gradual warming Monday through Thursday, to a few to 10 degrees above average by Wed/Thu. Winds will return to average next week, with daily afternoon sea breezes mountains westward and periodic, weak offshore winds in the deserts. The return of deeper low pressure aloft Thursday into the weekend will lead to slightly lowered temperatures and the return of the more typical "May Grey" cloudy weather with possible patchy drizzle.

AVIATION

161800Z...Coast/Valleys...Low clouds are beginning to break up along the coast though southern San Diego County looks to remain under low cloud cover for most of the period. Low cloud bases are expected to remain between 2000-4000ft MSL with a few clouds moving in and out AOA 1500ft MSL. Low clouds will increase in coverage after 23Z beginning in SD County, stretching north and filling inland valleys after 00Z. Low clouds are expected to reach coastal OC after 06-08Z. Minor VIS reductions (3-5SM) expected for some elevated inland valleys, with lower VIS where clouds intersect terrain.

Mountains/Deserts...Winds have been gusty out of the north to northwest and will continue through this evening. Gusts have already reached 25-35 knots in desert slopes and mountain passes, locally up to 50 knots. MOD up/downdrafts and local LLWS in lee of mountains. Winds will continue to strengthen into the afternoon with widespread gusts 35-45 knots, locally to 60 kts in wind prone locations. Winds will remain gusty through Sunday. Strong up/downdrafts in lee of mtns with BLDU and reduced VIS expected. Otherwise, SKC and VFR expected through the period.

MARINE

Gusty westerly winds with gusts 20-30 kt will develop in the outer coastal waters late this afternoon. The strongest gusts will occur near San Clemente Island. Seas of 7-10 feet with a 9-12 second period will generate choppy seas. Winds and seas will slowly diminish through the day Sunday. A Small Craft Advisory is in effect and contains more information.

BEACHES

A westerly swell from 290 degrees with a 9 to 10 second period will bring elevated surf of 4 to 6 feet, sets to 7 feet this afternoon through Monday morning. Highest surf at west to northwest facing beaches. The combination of elevated surf and high tides of 6.5 to 7 feet will result in minor tidal overflow, especially for beach parking lots and boardwalks. Surf will start to decrease Monday afternoon. A Beach Hazards Statement is in effect and contains more information.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement from 6 PM PDT this evening through Monday morning for Orange County Coastal Areas-San Diego County Coastal Areas.

Wind Advisory until 11 PM PDT Sunday for Apple and Lucerne Valleys-San Bernardino County Mountains-San Gorgonio Pass near Banning.

Wind Advisory until 11 PM PDT Sunday for Riverside County Mountains-San Diego County Deserts-San Diego County Mountains.

PZ...Small Craft Advisory until 7 AM PDT Sunday for Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.