'Surge Of Monsoonal Moisture,' Heat To Bear Down On SoCal

LOS ANGELES, CA — Showers and thunderstorms are expected to coincide with a heat wave to bring muggy conditions across the Southland thanks to a monsoonal weather system arriving Tuesday, weather officials said.

The National Weather Service issued warnings of thunderstorms, flash flooding, strong winds, isolated dry lightning that could ignite fires and sustained heat through Tuesday.

"Any storm could produce brief heavy rain, suddenly strong winds, dangerous lightning, fire starts," the NWS Los Angeles wrote on Twitter. "Stay weather aware today. If you hear thunder, seek shelter."

By Tuesday morning, some parts of the Southland were already experiencing a downpour, as scattered showers and thunderstorms reported in the deserts and mountains pushed westward toward coastal areas.

In Riverside County, the rains had already arrived in places like Banning and Temecula, with thunder and lightning expected along with the showers after 11 a.m.

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In inland areas of San Diego County such as Santee, Tuesday morning began with light rain, but thunderstorms were possible everywhere in the county before 11 p.m.

In Orange County, forecasters said coastal cities like Laguna Beach could see showers and thunderstorms throughout the day with temperatures hovering around the low 80s.

In Los Angeles, the morning began with cloud cover, and there's a 40 percent chance of showers and thunderstorms before 11 a.m.

Across much of the region, new rainfall was only expected to amount to less than a tenth of an inch, but higher amounts were possible in thunderstorms.

The "surge of monsoonal moisture" is joining a heat wave that has lingered throughout Southern California for the past week and is expected to last a few more days.

A heat advisory remains in effect for a large swath of the Southland and could potentially be extended for Wednesday.

"Hot daytime conditions with high temperatures of 96 to 107 degrees common, and warm overnight conditions," the National Weather Service wrote in its Tuesday discussion.

Forecasters said temperatures in the low to mid 90s were expected to persist in many Southern California communities this week, with triple-digit temperatures forecasted in some areas such as Palm Desert.

Weather Service officials urged residents to limit strenuous outdoor activities such as hiking to the early morning hours.

"Stay in air-conditioned spaces during the heat of the day. Check up on relatives and neighbors," the weather service wrote on Tuesday.

Forecasters say relief is on the way, with temperatures expected to drop toward the end of the week.