textproduct: San Diego

SYNOPSIS

Remnants from Rachel will continue to move out of the region today with isolated showers, mainly along and west of the mountains. An area low pressure will drop southward across the Western U.S. through early Tuesday, bringing breezy, cool conditions and a chance of light showers again over our region. High pressure begins to move over the Southwestern U.S. for the latter half of the week, and may interact with an area of low pressure to bring Santa Ana winds along with warmer/drier weather for all.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

Rachel's remnants brought widespread rainfall across the region. Valleys and coastal areas west of the mountains saw near one half inch to over 2 inches of rainfall in total, with mountain areas receiving 3-5"+ of rainfall. Current radar mosaic depicts light showers weakening over the area. Low level cumulus will continue to funnel in off the ocean through afternoon, but most lower elevations should see a brief lull in the rain. Coastal-facing slopes will see isolated light showers ongoing.

A 550 mb low pressure over eastern Oregon will continue drop southward into the Great Basin on Monday and Tuesday. This will bring a continued cooler and wetter pattern to start the work week across SoCal. As the low moves closer later tonight through Monday afternoon, we can expect an increase in coverage in light to locally moderate showers. The best chance for showers will be along and west of the mountains. Accumulations will be light, with most valley and coastal areas seeing less than one quarter of an inch of rainfall. This system will also bring colder air with it, with 850mb temperatures falling near 5-8C and 700mb temperatures falling near -3C. Snow levels will begin to drop further, most likely near 8000 ft, giving some light snowfall to some of our highest peaks late tonight into Monday evening. Monday will be the coolest day overall as the weather system moves in. High temperatures will be in the 40s and 50s across the mountains, with 60s and 70s elsewhere. Temperatures by early Tuesday morning will be in the 40s and 50s for western valleys, closer to 60 degrees at the coast. Remnant clouds and light showers may linger into Tuesday morning west of the mountains, but mostly clear conditions should prevail by Tuesday afternoon.

The low pressure system will push eastward into the southern Rockies by Wednesday, as high pressure off the Pacific begins to expand over California. This will bring a drying and warming trend with flow switching to weakly offshore. Temperatures will be closer to normal for the coastal and western valley locations in the 70s to near 80 degrees. By Thursday, models show a potential area of low pressure forming somewhere over the Desert Southwest as a ridge amplifies over the West Coast. The tighter gradient between these would create a stronger offshore flow pattern, where increased Santa Ana winds will become possible from the coastal slopes into the western valleys. There is still low confidence on where the low tracks, which will help determine not only how strong winds will be, but also how warm areas west of the mountains and how cool the mountains and deserts become.

AVIATION

111730Z...Coastal/Inland Basin...SCT SHRA/-SHRA through this early afternoon, then becoming ISO SHRA by around 23z through the remainder of the TAF period. MVFR CIGs and VIS 3-6SM with SHRA/RA. Gusty SW winds gusting 20-25 kts (up to 35 kts in the foothills) through 20z. Otherwise, SCT-OVC clouds based 3-5 kft through much of the TAF period.

Mountains and deserts...ISO to SCT -SHRA/SHRA in the mountains, and more ISO for the deserts, gradually tapering off throughout the TAF period. Gusty SW winds gusting to 35-55 kts over ridgetops, mountain passes and desert slopes through 03z Mon, becoming more localized thereafter.

MARINE

West winds gusting 20-30 knots expected throughout the coastal waters through this afternoon. Large fresh swell from the northwest will combine with south swell associated with Tropical Storm Rachel and wind waves to create combined seas 6 to 10 feet today. Choppy, steep, mixed seas and gusty winds will produce conditions hazardous to small craft.

Calmer winds and seas expected Monday through the work week.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Warning until 3 PM PDT this afternoon for Orange County Coastal Areas-San Diego County Coastal Areas.

Beach Hazards Statement until 10 PM PDT this evening for Orange County Coastal Areas-San Diego County Coastal Areas.

Coastal Flood Advisory until 2 PM PDT Tuesday for Orange County Coastal Areas-San Diego County Coastal Areas.

Wind Advisory until 5 AM PDT Monday for Apple and Lucerne Valleys-Coachella Valley-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 10 PM PDT this evening for Coastal Waters from San Mateo Point to the Mexican Border and out to 10 nm-Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.