Marine Weather and Tide Forecast for Costa Mesa, CA

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

A trough of low pressure will start to dig into the Pacific Northwest later tonight. Cross sections of our local WRF are indicating a fairly deep saturated layer for tonight into Saturday morning. Current indications are this layer will be saturated enough to produce areas of drizzle or light rain west of the mountains and on mountain slopes during that time. Minimal accumulations are expected with chances of rainfall totals reaching or exceeding 0.10" at 5 percent or less.

As the low pressure system begins to dig south into the Great Basin Saturday afternoon and evening, rain chances increase especially for San Diego County. Any rainfall is expected to be light, but more widespread across the coastal basin compared to what is expected tonight into Saturday morning. It's unlikely rainfall totals will exceed 0.20" for the coast and valleys and 0.40" for the coastal mountain slopes. The most likely places for accumulating rainfall are in the San Diego coast, valleys, and mountains.

Stronger, gusty southwest to west winds are expected for the desert slopes of the mountains and deserts for Saturday afternoon into Saturday night. Stronger gusts of 45 to 55 mph with isolated gusts to 70 mph in the northern Coachella Valley below the San Gorgonio Pass are expected. Gusty west winds will continue Sunday afternoon and evening but not quite as strong with gusts to 40 to 50 mph and isolated gusts to 65 mph through wind prone passes.

High pressure will bring dry weather with warming Monday through Thursday. Conditions will warm quite rapidly between Sunday and Monday, especially in the valleys and mountain foothills due to a brief period of offshore winds. Highs in the valleys and foothills will be up to 10 degrees warmer on Monday compared to Sunday. As early as Tuesday, highs along the coast and valleys will be 10 to 15 degrees above average. The warming will spread further inland for Wednesday and Thursday. For Wednesday and Thursday, NBM chances for high temperatures in the warmer portions of the Inland Empire to exceed 100 are around 45 to 55 percent with NBM chances for the warmer portions of the lower deserts to exceed 110 on Thursday at 5 to 10 percent. The marine layer will become shallower with night and morning coastal low clouds not extending inland past the far western valleys for Wednesday and Thursday.

AVIATION
162030Z
Coast/Valleys
Low clouds have mostly cleared this afternoon with only FEW-SCT coverage based near 2000 ft MSL lingering across portions of the coasts. Low clouds based near 1500- 2000 ft MSL fill back in and push ashore after 02z, filling the entire coastal basin to the foothills by 09-11z. Patchy drizzle is possible across the coasts and the western valleys between 08-18z and may linger into the afternoon along the coasts. Drizzle may locally lower VIS to 4-6 SM and CIGs near 1000-1500 ft.

Mountains/Deserts...SCT high clouds late today and tonight. After 22z, pockets of westerly surface winds increase to 25-30 knots with gusts to 40 knots through mountain passes into adjacent deserts.
This could produce intermittent strong up/downdrafts in the lee of mountains such as vcnty KPSP.

MARINE
Onshore winds gusting near 20 kts late Saturday into early Sunday may lead to some choppy seas in the outer waters near San Clemente Island for Saturday evening. Otherwise, no hazardous marine conditions expected through Wednesday.

BEACHES
Elevated surf will impact beaches Sunday and Monday. Expected surf of 4-6 feet would produce a high rip current risk.

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



SGX WATCHES/WARNINGS/ADVISORIES
CA...Wind Advisory from noon Saturday to 2 AM PDT Sunday for Apple and Lucerne Valleys-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.

PZ...None.