Swell Matrix

Area Forecast Discussion

National Weather Service San Diego CA

807 pm PDT Fri Mar 23 2018


A trough over the West will keep below average temperatures in place into early next week. A few very light showers or sprinkles may occur Saturday night into Sunday morning. Any accumulations will be negligible. Offshore winds possible by the middle of next week, along with a warming trend and drier weather.


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

At 800 PM, A closed low centered 450 miles west of the Washington coast was producing showers north of San Francisco. Fair weather prevailed over the southern half of California. Winds were light in SoCal.

The closed low currently off the coast of Washington is expected to weaken (filling from 523 DM today to around 548 DM at 500 mb) and transition to an open wave as it drifts east into the central Rockies by Monday. This will keep heights depressed in SoCal, leading to a cooling trend this weekend. Look for afternoon highs to range from 4-8 degrees below average at the coast to 14-20 degrees below average in the mountains by Sunday. Cooling below 700 mb and a shallow layer of moisture may result in sufficient instability for a few light showers or drizzle Saturday night over the coast and valleys. Insatiability will remain present Sunday night, but available moisture remain in question. A few light snow showers can't be ruled out for the mountains, especially Saturday night into Sunday. Any accumulation will be negligible, with only a couple hundredths possible.

By the middle of next week, the forecast hinges on the potential development of a closed low in the Desert Southwest. If this low sets up in the right position, there is a potential for Santa Ana Winds in our northern areas (Santa Barbara east to the northern Inland Empire). Run to run consistency gives the forecaster some confidence that this will occur. However this is a finicky solution that is dependent on the closed low producing strong northerly winds (between 850 and 600 mb) over the region. So for the time being, the wind forecast has been tempered a bit. Outside of the wind potential, a warming trend and dry weather are anticipated for the second half of next week.


240235z, Coastal areas and Valleys, Low clouds increasing in coverage tonight with BKN-OVC cigs 1000-2000 ft MSL and tops to 2500 ft MSL through 17Z Saturday. After 17Z Saturday SKC-SCT with bases around 3000 ft MSL.

Mountains and Deserts: Areas of vis 1-3 miles in fog along the coastal slopes 1500-2000 ft MSL through tonight, otherwise mostly clear with unrestricted vis through Sat. Gusty northwest winds 15-20 kt til 06Z at KPSP and KTRM.


Northwest winds increasing late tonight and continuing through Sunday afternoon, strongest over the Outer Waters with gusts 25 to 30 kt. The winds along with combined seas of 7-10 ft at times and steep waves will produce hazardous boating conditions. A Small Craft Advisory will be in effect for the Outer Waters this weekend.

Watches, Warnings, Advisories

Ca, NONE. PZ, Small Craft Advisory from 5 AM Saturday to 8 PM PDT Sunday for Waters from San Mateo point to the Mexican Border Extending 30 to 60 nm out including San Clemente Island.

Visit this site often? Consider supporting us with a $10 contribution.
Learn more

Share this forecast!