textproduct: San Diego

SYNOPSIS

Building high pressure will bring a warming trend through Wednesday, with moderate to high HeatRisk for the deserts. Mid level moisture in southerly flow aloft will bring a slight chance of showers and thunderstorms this afternoon through Wednesday afternoon for the mountains of San Bernardino and Riverside Counties east and northeastward across the deserts of southern California. This will be followed by a cooling trend for Thursday through the weekend. Southwest to west winds will strengthen for Thursday through Saturday in the mountains and deserts, with gusts on Saturday of 30 to 40 mph locally to 65 mph in the northern Coachella Valley below the San Gorgonio Pass.

Updated Aviation and Beaches Discussions

This afternoon...Mid-level moisture in southerly flow aloft is producing some high-based convective elements across the mtns and deserts of SoCal. This elevated convection could produce isolated dry lightning strikes and locally gusty winds. This could result in fire starts. See the Fire Weather discussion below.

The marine layer is about 2000-2500 ft deep with a strong inversion so some low clouds are persisting at the beaches. The moisture aloft could disrupt the radiation cooling tonight so low cloud coverage may be less tonight than last night. Temperatures are near or a few degrees lower west of the mtns than at this time yesterday while the mtns and deserts are generally warmer by as much as 10 degrees in a few locations.

High pressure building in from the southeast will continue the warming trend through Wednesday with a minor drop in daytime high temperatures on Thursday. High temperatures on Wednesday will range from a few degrees above average near the coast to 4 to 8 degrees above average inland. High temperatures on Wednesday will range from the lower to mid 70s near the coast to the 90s for the Inland Empire with 108 to 112 for the lower deserts. Tonight will be much warmer as well with low temperatures Wednesday morning mostly in the 80s for the lower deserts. The marine layer will remain around 2000 feet deep with night and morning coastal low clouds extending inland into portions of the western valleys late each night. The mid-level moisture will continue to move into SoCal from the south but the disturbance moving over us today will be mostly to our north by tomorrow and the high pressure will increase stability making deep convection less likely tomorrow.

A low pressure system moving southward out of the Gulf of AK will strengthen the onshore slow across southern California into the weekend. Southwest to west winds for the mountains and deserts during the afternoon and evening will strengthen for Thursday through Saturday, with gusts on Saturday of 30 to 40 mph locally to 65 mph in the northern Coachella Valley below the San Gorgonio Pass. The marine layer will deepen with night and morning coastal low clouds spreading farther into the valleys late each night.

The low pressure system will also bring a cooling trend through the weekend, with high temperatures on Sunday as much as 15 degrees below average for the mountains and inland valleys. High temperatures on Sunday will range from around 70 near the coast to mid 70s to lower 80s for the Inland Empire with the mid 90s to 102 for the lower deserts. High temperatures for next Monday and Tuesday will be marginally warmer.

AVIATION

240000Z...Coast/Valleys...Patchy low clouds based 1300-1700 ft MSL are expected to return to coastal San Diego County after 03z Wed and coastal Orange County after 08z Wed. However, coverage should remain limited (especially in Orange County) with intermittent clearing possible into the early morning hours. 70-80% chance for cigs at KSAN and KCRQ, but only 50-60% chance at KSNA. 30% chance for clouds to spread into western valleys up to 20 miles inland. Regardless of coverage, low clouds should clear out of land areas by 18z Wed, though they may stick to San Diego County beaches through Wednesday afternoon.

Mountains/Deserts...VFR conditions expected through the TAF period with SCT-BKN high clouds AOA 15000 ft slowly decreasing in coverage through Wednesday.

MARINE

No hazardous marine conditions are expected through Sunday.

BEACHES

Surf will continue to increase this evening with the arrival of a 3 foot 15 to 18 second period south swell from 190 to 210 degrees. Surf of 4 to 6 ft is expected through Thursday. Expect locally hazardous swimming conditions and strong rip currents through the week. 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 Thursday evening for Orange County Coastal Areas-San Diego County Coastal Areas.

Red Flag Warning until 11 AM PDT Wednesday for Victor Valley - Apple Valley -Lucerne Valley -Johnson Valley.

Extreme Heat Warning from 11 AM Wednesday to 8 PM PDT Thursday for San Diego County Deserts.

PZ...None.