Marine Weather and Tide Forecast for Tustin, CA

DISCUSSION
FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

The marine layer continued to deepen this evening but at the same time breaks in the clouds got bigger. While the breaks provided a more colorful sunset, the almost-May gray will gather more fully overnight. A trough of low pressure will move through SoCal Saturday. Its approach today has already deepened the marine layer to around 7,000 feet deep. Tonight and Saturday morning it will bring scattered light showers mainly near the coast, with little if any accumulation. As the trough moves in, a cold front with an associated band of showers and isolated thunderstorms will track through the region west to east between 11 am and 3 pm Saturday.
Thunderstorm chances are quite small. This main band will be followed by post-frontal showers mainly in San Diego County and mountains through the night or even into Sunday morning. Total precipitation will range from a few hundredths near San Diego to 0.75 inch in the front range of the mountains. Any rainfall rates will fall below thresholds of concern for flooding or any debris flows on burn scars. Snow will fall in the mountains above 5,000 feet elevation, but will probably only stick above 6,000 feet. Up to 5 inches are expected, most likely around places like Baldy ski resort and Running Springs. The system will also bring winds, an easy forecast since they have already started. Gusts of 45-55 mph with isolated gusts 65 mph over and through mountains into adjacent deserts will continue through Saturday as the system rolls through.
Conditions dry out and warm up Sunday, although a secondary shortwave rotates through the region on the dry side of the longwave trough on Sunday. That will keep things cooler than normal into Monday before high pressure builds a little better for Tuesday.
Accordingly, temperatures will climb next week as a weak high pressure ridge seems to dominate the longwave pattern. This will allow a more stable and seasonal marine layer to rebuild and provide coastal low clouds during the nights and mornings. Within the ridge there are some weak low pressure waves that won't do much, but would modulate temps and marine layer depth and its cloud extent and duration. Most model guidance and ensembles tend to bring in lower pressure for late next week, which would provide cooler and cloudier weather Friday and beyond.

AVIATION
260415Z
Coasts/Valleys/Coastal Mountain Slopes
SCT-BKN clouds with bases 3000-6000 ft MSL will gradually increase overnight and continue through Sat evening. Mountain terrain will be obscured at times in clouds. Isolated SHRA will occur overnight and Sat morning, then become SCT or even numerous Sat afternoon with local VIS 3-5 miles and bases locally as low as 2000 ft MSL. There is a slight chance of TS Sat afternoon with any lightning strikes being isolated. SHRA will be isolated/SCT Sat evening.

Mountains/Deserts...Areas of westerly winds with gusts 30-50 kt will continue through Sat evening, strongest from the mountain crests through the desert mountain slopes. PSP could periodic gusts 30-35 kt at times, especially Sat afternoon/evening. Isolated SHRA/SHSN will occur in the mountains tonight and Sat morning, becoming SCT/locally numerous Sat afternoon/evening with widespread terrain obscurations in clouds.

MARINE
There is a slight chance of thunderstorms over the waters Saturday afternoon and evening which may bring brief heavy rainfall, reduced visibility, brief gusty and erratic winds and lightning.
Otherwise, no hazardous marine conditions are expected through Wednesday.

BEACHES
Elevated surf of 3 to 6 feet with sets to 7 feet will occur Saturday through Tuesday, peaking Sunday night and Monday, and highest on south facing beaches. Strong rip currents will occur. There is a slight chance of thunderstorms at the beaches Saturday afternoon and evening, with lightning and gusty winds possible with any storm.

SKYWARN
Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.

SGX WATCHES/WARNINGS/ADVISORIES
CA...Winter Weather Advisory from 9 AM to 11 PM PDT Saturday for San Bernardino County Mountains.

Wind Advisory until 11 PM PDT Saturday for Apple and Lucerne Valleys-San Diego County Deserts-San Gorgonio Pass near Banning.

PZ...None.