textproduct: San Diego

SYNOPSIS

The marine layer will remain around 5000 feet through Wednesday. There could be some drizzle or light rain from this deep marine layer at times, mainly late at night into the morning into Thursday morning. High temperatures will lower several degrees for Tuesday and Wednesday to as much as 20 to 25 degrees below average for the mountains on Wednesday. Southwest to west winds in the mountains and deserts will strengthen for this afternoon through Wednesday night, with gusts of 40 to 50 mph with isolated gusts to 70 mph through the passes. There will be warming for Friday through next weekend with the marine layer becoming shallower.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

New Aviation and Marine Discussion...

This afternoon...The marine layer is about 5000 ft deep with widespread low clouds west of the mtns, although there are breaks in the cloud layer with some reverse clearing at the coast. Temperatures are generally lower than at this time yesterday, with some locations in the mtns and high deserts as much as 15-20 degrees cooler.

The low pressure system with a closed upper low over NorCal will move south through Thursday before turning east on Fri, moving into the Rockies by Saturday. High temperatures today will be as much as 10 to 15 degrees lower than yesterday for some inland areas and as much as another 5 to 10 degrees cooler on Wednesday for the mountains and deserts. High temperatures in the mountains on Wednesday will be as much as 20 to 25 degrees below average. High temperatures on Wednesday will be mostly in the 60s for the coast and valleys and in the upper 70s to mid 80s for the lower deserts, with the mountains mostly in the 40s and 50s and the high desert in the 60s.

The marine layer will remain about 5000 ft deep (give-or-take) through Thursday. The deep marine layer and thick saturated layer could bring patchy drizzle to areas west of the mtns tonight/Wed morning and again Wed night into Thu morning, although measurable precipitation is not very likely.

This low pressure system will also bring stronger onshore flow resulting in southwest to west winds gusting 40 to 50 mph at times in the mtns and deserts. Gusts of up to 65 mph could also occur in the northern Coachella Valley below the San Gorgonio Pass. The strong winds will likely last from today through Wed night before weakening on Thu.

A warming trend begins on Friday as the low pressure system begins to move east but daytime temperatures will likely remain mostly below normal through Sat. The warming continues into early next week. Forecast details are uncertain for this period due to the spread among model solutions but next Tue looks like it will be the warmest day, with temperatures near or several degrees above normal. SoCal will remain under weak troughing aloft with (weaker) onshore flow at the surface which will likely moderate temperatures west of the mtns.

AVIATION

270430Z...Coast/Valleys/Foothills...Patchy drizzle is already coming down in some areas this evening with chances continuing through 11Z. BKN/OVC low clouds based around 3000-4000 ft MSL have filled back into the coastal basin with the occasional bases coming in and out around 2500 ft MSL through 13Z. Low clouds are expected to stick around for most of the period with the occasional break in clouds mainly in the Inland Empire and OC after 19-21Z. Higher Mountains/Deserts...Partly cloudy skies and VFR conditions expected through the TAF period. Winds continue to gust out of the west easing slightly after 17Z before increasing again after 21-22Z. Widespread gusts up to 30-40 kts with isolated gusts to 65 kts through the passes will be possible.

MARINE

Winds and seas have increased, continuing into early this Wednesday morning, generating hazardous conditions for small craft in the outer waters, especially near San Clemente Island. For more details, see the Small Craft Advisory product. Winds and seas will decrease Wednesday night, with no hazardous marine conditions expected thereafter through Sunday.

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 Thursday for Riverside County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.

Wind Advisory until midnight PDT tonight for Apple and Lucerne Valleys.

PZ...Small Craft Advisory until 1 PM PDT Wednesday for Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.