Marine Weather and Tide Forecast for Mount Laguna, CA

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

Cloud coverage will continue to increase as a trough of low pressure moves across the Pacific Northwest this afternoon and evening.
Tuesday is expected to be the coolest day of the week, with temperatures cooling an additional 10 to 15 degrees for inland locations. Winds over the mountains and deserts at 1 PM were mainly gusting in the 40 to 50 mph range. Stronger winds will continue over the mountains and into the deserts through early Wednesday morning.
Winds will be strongest on the desert mountain slopes, through passes, and into the deserts. Peak gusts of 40 to 55 mph expected in the deserts, with local gusts closer to 65 through wind prone passes like the San Gorgonio Pass. On the desert mountain slopes, peak gusts will be 50 to 60 mph.

As the trough digs south into the Great Basin tonight into Tuesday, the marine layer will deepen. Widespread low clouds can be expected from the coast to the mountain slopes. The moisture will be deep enough that when a shortwave moves through the mean flow on Tuesday morning and when the trough axis passes Tuesday evening light showers may develop. Any shower development is most likely on the coastal mountain slopes, with the potential for some drizzle west of the mountains mainly on Tuesday morning/early afternoon. Ensemble guidance is showing a 40 to 60 percent chance of rainfall accumulations reaching or exceeding 0.10" on the coastal mountain slopes, with a 20 to 40 percent chance of rainfall accumulations reaching or exceeding 0.20" on the coastal mountain slopes. For the coast and valleys there is a less than 10 percent chance for accumulations to reach or exceed 0.20". Local high resolution WRF guidance and HRRR guidance continues to indicate rainfall rates less than 0.10" per hour Tuesday morning and evening, with only a 10 percent chance of rainfall rates exceeding 0.10" per hour on the coastal mountain slopes.

The main trough axis will be to our east by Wednesday, which will allow for the winds to weaken, dry conditions to return, and for high temperatures to warm 5 to 10 degrees, locally up to 15 degrees warmer in the mountains. Most guidance indicates we will maintain an overall troughing pattern over the western United States for the remainder of the week, with a ridge of high pressure building over the Eastern Pacific. The overall troughing pattern will keep high temperatures just below the seasonal normal, maintain at least night and morning low cloud coverage, and elevated afternoon sea breezes.
Over the weekend, there becomes some disagreement in the upper level pattern which will impact whether we get warmer conditions and a squashed marine layer or increased cloud coverage, winds, and cooler conditions. For example on Saturday, 40 percent of solutions show a weak trough passing through the Intermountain West, 40 percent of solutions show a deeper trough, and 20 percent show ridging over the West Coast. By Sunday, 50 percent of solutions indicate ridging with 30 percent of solutions indicating a deeper trough.

AVIATION
122040Z
Coast/Valleys
BKN low clouds based near 2000 ft MSL are slowly filling in near the San Diego Co coast at this hour. Bases will rise closer to 2,500-3,500 feet overnight and after 05Z in Orange County and the Inland Empire. Low clouds mostly clearing for northern areas, but will struggle to clear in San Diego County in the afternoon hours.

Mountains/Deserts
SCT-BKN High clouds AOA 20000ft through tonight, but otherwise, VFR conditions through tonight. Winds becoming more widespread and increasing 30-45 kts this afternoon and evening up to 55 kt along desert slopes and through mountain passes with STG UDDFS possible. BLDU in windier corridors, primarily in the deserts.
Gusty winds continue on Tuesday.

MARINE
Strong west-northwest winds will continue through Tuesday, with sustained winds of 15 to 20 kt and gusts to 25 kt across the outer coastal waters leading to hazardous conditions for small craft, strongest winds near San Clemente Island. A Small Craft Advisory remains in effect through late Tuesday night. Winds briefly diminish late tonight through Tuesday morning, but will strengthen again Tuesday afternoon and evening. Winds taper off by Wednesday morning.

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



SGX WATCHES/WARNINGS/ADVISORIES
CA...Wind Advisory until 5 AM PDT Wednesday 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...Small Craft Advisory until 11 PM PDT Tuesday for Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.