textproduct: San Diego

SYNOPSIS

Above average high temperatures early this week will cool to below average during the latter half of the week throught the weekend. Coastal low clouds will spread farther into the valleys during the latter half of the week each night and morning as the marine layer slowly deepens.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

Coastal low clouds cleared on schedule this morning, but have been persistent to hang at the immediate coast in most of San Diego County. Monsoon moisture over the mountains and deserts is being manifest by mid level clouds, including cumulus clouds over the mountains. Isolated showers are expected along the Baja spine this afternoon, with only a ghost of a chance just north of the border (at noon, there were legit thunderstorms in and around Yuma, AZ). Very similar weather will continue through Tuesday, with similar marine layer and monsoon influences. The upper level pattern shows a very weak trough over SoCal underlying a strong ridge over the Pac NW (producing some record high temps in Portland and Seattle), and no discernible change through Tuesday night. The marine layer will continue more or less at its current depth of about 1000-1500 feet deep through Tuesday, which will preclude low clouds and fog from entering the Inland Empire. Temperatures will remain just a few degrees above seasonal averages through Tuesday. Monsoon moisture hangs around for one more day, so you'll continue to see some mid level cumulus and altocumulus clouds, especially over the mountains Tuesday afternoon. Very weak low pressure aloft Wednesday helps deepen our marine layer and sweeps the monsoon moisure away. A trough of low pressure begins to develop off the West Coast around Thursday and deepens Friday and Saturday as it advances through California. That will flip temperatures from a few degrees above average to a few degrees below on Wednesday and especially Thursday. The marine layer will respond by deepening Wednesday morning, and extending the nocturnal coastal clouds farther inland each night and morning into Saturday. There should be stronger onshore winds through mountain passes and into deserts each afternoon and evening, looking strongest on Friday when gusts of 40-50 mph are likely through the wind-prone mountain passes like San Gorgonio Pass. After the trough passage on Saturday, weak high pressure returns Sunday, which will reverse the temperature and marine layer trends. In other words, a modest warming trend and less extensive coastal clouds in a shallower marine layer come Sunday.

AVIATION

151800Z...Coast/Western Valleys...Patchy low clouds 1000-1500 feet MSL will persist along the immediate coast. Low clouds with similar bases will push ashore in San Diego County after 02Z and in Orange County after 06Z. Scatter out Tuesday will be 16-18Z.

Mountains/Deserts...VFR conditions are expected through Tuesday morning, with occasional SCT-BKN clouds around 15000 feet MSL. Cumulus around 10000 feet MSL over mountains through 02Z. Breezy westerly winds gusting 25-30 kts through mountain passes and into deserts 22-09Z.

MARINE

No hazardous marine conditions are expected through Friday.

BEACHES

Elevated surf and strong rip currents continue through Friday. Surf of 3-6 feet and sets to 7 feet are expected at south-facing beaches. Surf for southern San Diego County will be slightly lower, but hazardous swimming conditions with high rip current and longshore current risk will still exist. See the Beach Hazards Statement for more details.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement through Friday evening for Orange County Coastal Areas-San Diego County Coastal Areas.

PZ...None.