Swell Matrix

Area Forecast Discussion

National Weather Service San Diego CA

902 am PDT Wed Jun 19 2019

Synopsis

High pressure aloft across California will bring fair and warmer weather today. A trough of low pressure will move through the region Thursday into Saturday for cooler weather, more clouds, breezy evening winds in the mountains and deserts, and some drizzle or light showers in the coastal basin during the nights and mornings. High pressure rebounds next week for fair and seasonal weather.

Discussion

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

Low clouds didn't fill the entire coastal basin this morning, reflective of the fact that the marine layer that rebuilt overnight did so more shallow. The cloud deck itself was also thinner. These factors indicate a quicker clearing pattern this morning, but maybe not as complete of clearing as we got late Tuesday afternoon. High pressure aloft peaks out today so inland temperatures will peak also. A low pressure trough will push through the West Thursday through Saturday. This will deepen our marine layer, assisted by a coastal eddy, and extend the clouds fully inland up the mountain slopes. The lifting and deepening of clouds should produce areas of drizzle Thursday night and Friday morning, and patchy drizzle or light showers Friday night into early Saturday. Any accumulations will be very light; it's June. Clearing on Friday will be slow, if clearing happens at all: a damp and murky start to summer in the coastal basin (solstice at 854 AM PDT Friday). Strong winds will develop Thursday and Friday afternoons and evenings in parts of the mountains and deserts. Some areas will get gusts over 40 mph, with isolated gusts topping 50 mph. High pressure rebounds with a touch of offshore flow over the weekend and the marine layer will obey by going more shallow. That will mean less extensive coastal clouds during the nights and mornings and a warming trend. Next week model guidance features a building trough along the West Coast, but at the same time a building ridge over the interior Southwest. Socal will be stuck in the middle of this pressure sandwich under dry southwest flow aloft. All that will mean is we'll get seasonal weather for the first week of summer.

Aviation

191530z, Coast/Valleys, Stratus with bases 1000-1800 ft MSL, with locally lower bases around 700 ft MSL, have reached as far inland as KSBD. Clouds clearing inland 16-18Z and 18-20Z along the coast, though some beaches may remain BKN-OVC into the afternoon. Stratus moving back inland after 02Z with bases near 1500-2000 ft MSL, spreading into the inland valleys after 10Z. Local vis 3-5 SM in BR/HZ in the valleys between 10-16Z Thursday.

Mountains/Deserts, A few cumulus clouds developing over the mountain crests this afternoon, dissipating this evening. Otherwise clear with unrestricted vis through Thursday. West winds with gusts of 25-30 kt will pick up over the mountain crests, desert mountain slopes, and below passes after 02Z. Areas of MOD UDDFTS over and east of the mountains are possible.

Marine

No hazardous marine conditions are expected through Sunday.

Watches, Warnings, Advisories

Ca, NONE. PZ, NONE.

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