Swell Matrix

Area Forecast Discussion

National Weather Service San Diego CA

840 pm PDT Thu Sep 21 2023


High pressure to the south will bring warming for the weekend, but with high temperatures remaining below average. The marine layer will become shallower with night and morning coastal low clouds not extending inland much past the western valleys for the weekend into next week. Tropical mid and high clouds in southwest flow aloft could bring some virga or sprinkles in the mountains around Friday night. Not much change or slight cooling for the early and middle part of next week.


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

Evening Update, West winds currently gusting 25-45+ MPH along mountain passes and desert slopes will slowly subside overnight. Satellite imagery depicts low clouds building back into areas west of the mountains. The marine layer will become more disrupted this evening into Friday morning due to high clouds starting to stream into the area, so intermittent clearing may occur. High clouds are making their way from the south this evening. These are associated with weakening Tropical Storm Kenneth approximately 1,000 miles southwest of San Diego. This system will continue to bring an increase in high clouds overnight through much of the day on Friday. Precipitable water values look to go over one inch tomorrow for southern areas. As with the previous forecast discussion, some sprinkles are not out of the question, especially in San Diego County.

These clouds and a trough to the north will lead to another well below average day with highs 5-15 degrees below average. Quiet weather with some slight warming is expected for much of next week with better clearing near coastal areas.


220230z, Coast/Valleys/Foothills, Low clouds increasing in coverage through 14Z. Bases will be 2000-3000 ft MSL with tops to 3500 ft MSL, obscuring higher terrain with VIS reduced to 1-3 miles where clouds and terrain intersect. Expect clearing 17Z-19Z.

Mountains/Deserts, SCT-BKN clouds at or abv 15000 ft MSL with unrestricted VIS into Friday morning. Gusty west to northwest winds through mountain passes and into deserts, weakening after 08Z. Gusts of 35-45 knots expected, with peak gusts to 55 knots. Areas of LLWS and MOD up/downdrafts over and east of the mountains, along with patchy BLDU reducing VIS to 3-5 miles.


Breezy northwest winds may create rough boating conditions near the entrance of the San Diego Bay Saturday afternoon. Northwest winds with gusts approaching 20 kts in the outer waters are expected each afternoon early next week.

Watches, Warnings, Advisories

Ca, None. PZ, None.

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