Swell Matrix

Area Forecast Discussion

National Weather Service San Diego CA

338 am PDT Mon apr 24 2017

Synopsis

A low pressure system moving inland to the north today will bring stronger onshore flow with strong gusty west winds in the mountains and deserts, inland cooling, and coastal low clouds extending into the inland valleys. Slightly warmer on Tuesday with greater warming and weaker winds on Wednesday under high pressure aloft. A trough of low pressure moving southeastward through the Great Basin will bring stronger onshore flow for Thursday night and Friday with cooling, followed by weaker offshore flow for Saturday with warming for next weekend as high pressure strengthens off the West Coast.

Discussion

For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,

Short Term

(today through Wednesday), A low pressure system moving inland to the north today will bring stronger onshore flow through tonight. Significant cooling that developed over most areas except for the lower deserts on Sunday will spread farther inland today. Gusty west winds in the mountains and deserts will strengthen with strongest winds for late afternoon through late evening. The marine layer has deepened to around 3000 feet with coastal low clouds extending into the far inland valleys early this morning. A deep marine layer will continue into Tuesday morning, then become shallower into Wednesday as high pressure over the subtropical eastern Pacific expands into California. High temperatures will warm to near average on Tuesday and around 5 degrees above average on Wednesday.

Long Term

(Thursday through Sunday), A low pressure system will move southeastward through the Great Basin on Thursday. This will bring stronger onshore flow across Southern California for Thursday night and Friday with strong gusty west winds in the mountains and deserts. Slow cooling will develop west of the mountains on Thursday and spread farther inland on Friday with high temperatures on Friday cooling to near average. Weaker offshore flow will follow for Friday night into Saturday with locally gusty north to northeast winds. High pressure aloft off the West Coast will bring warming for next weekend beginning west of the mountains on Saturday and spreading farther inland on Sunday.

Aviation

240900z, Coast/Valleys, Low clouds will shroud most of the coastal basin this morning through 17Z. Bases will be 1500-2000 feet msl with tops up to 3000 feet. Areas of vis reduced where clouds and terrain intersect. Low clouds to return mainly in San Diego county after 03Z this evening with bases 2000-2500 feet msl.

Mountains/Deserts, West winds with gusts 25-45 kt will produce mod- stg up/downdrafts and LLWS over and east of the mountains this afternoon through tonight.

Marine

Northwest winds will increase today and continue through Tuesday evening with gusts to 25 knots. The winds and building swell will produce combined seas of 10-12 feet. A small craft advisory is in effect through Tuesday evening in the outer waters. Winds and seas could be hazardous again Thursday through Friday.

Beaches

Mixed swell will produce above average surf with some sets reaching 7 feet today. A Beach Hazards statement in effect and the surf forecast detail the hazards.

Watches, Warnings, Advisories

Ca, Wind Advisory from 2 PM this afternoon to 3 AM PDT Tuesday for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass Near Banning.

Beach Hazards Statement through this evening for Orange County Coastal Areas-San Diego County Coastal Areas.

PZ, Small Craft Advisory from 5 PM this afternoon to 10 PM PDT Tuesday for Waters from San Mateo point to the Mexican Border Extending 30 to 60 nm out including San Clemente Island.

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