textproduct: San Diego

SYNOPSIS

Tropical moisture will increase over the region through Thursday. Showers and scattered thunderstorms will be expected, where some may be locally heavy with localized flooding across the mountains and the deserts. Moisture will decrease by Friday into the weekend, with drier weather across the area with a lower chance across the mountains and deserts. There will be a subtle warming trend for this weekend into next week with drier weather.

SHORT TERM

Increasing clouds and moisture have overspread the area this afternoon as post tropical storm Mario continues to weaken. Radar shows weak thunderstorms beginning to form over the mountains, with greater coverage in rain across northern Baja. The chance for showers and storms will increase from south to north through this afternoon and evening across Southern California. Latest model data shows storms dissipating overnight, where a brief lull in activity is expected as an expansive mid level cloud deck moves over the region. Another rather humid night will occur again tonight with lows near 70 degrees west of the mountains into the high desert. The humidity will stick around through Friday.

The tropical moisture will continue to move northward on Thursday, bringing the greatest chance for the heaviest showers and thunderstorms across the region. Hi-res models indicated heavier downpours possible as daytime heating and higher instability will foster an environment for growing thunderstorm activity. Some models indicate hourly rain rates near 3/4" to 1" across these regions, so a Flood Watch has been issued for early Thursday morning through night, with heaviest rainfall expected on Thursday afternoon and evening. Be on the lookout for flooded roadways and areas near recent burn scars to impact communities and travel. Storm activity will calm by Friday morning, with best chances for showers to spring up across the mountains and deserts.

The weekend will look much drier as a trough offshore moves closer to the area. There may be enough instability and moisture leftover for a shower or two across the mountains and the deserts each afternoon. Models indicate the trough forming into a closed low by early next week, which makes for a fickle weather forecast. While precip is not out of the question, most areas are expected to remain dry with near average temperatures and a deeper marine layer.

MARINE

The remnants of Mario will bring a slight chance of thunderstorms today through Friday morning, greatest chances Thursday starting in the early morning. Any storm could briefly produce lightning, gusty variable winds, and choppy seas. Additionally, gusts around 20 kt possible in the vicinity of San Clemente Island this evening through early Thursday morning.

No hazardous marine conditions are expected Friday through Monday.

BEACHES

There is a slight chance of lightning today through Friday morning, greatest chances Thursday starting in the early morning.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Flood Watch from late tonight through late Thursday night 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...None.