Heat wave continues: T-storms, flash flooding possible

Flash flooding threatened the Southland Thursday as "excessive heat'' continued to plague the region and high surf slammed the coast, accompanied by dangerous rip currents.

The National Weather Service this morning issued a "Hazardous Weather Outlook'' in which it summed up Thursday's expected conditions this way:

"Temperatures will be 10 to 15 degrees above normal and will create heat-related issues this afternoon and evening. Dangerous surf and rip currents will continue at most beaches. Thunderstorms will bring the potential for flash flooding in the mountains and the Antelope Valley.''

Additionally, high humidity shrouded the region, causing temperatures to feel even higher than they really are. The humidity in Los Angeles was at the low- to mid-60 percent level this morning and expected to come down to between 30 and 50 percent -- still high -- this afternoon, said NWS Weather Specialist Stuart Seto.

"Maximum temperatures will reach dangerous levels across much of Southern California again'' Thursday, warned a NWS statement. "The peak of the heat event will continue on Thursday, though Friday will only be a few degrees cooler.''

Temperatures will fall slightly over the weekend ``but will remain above normal'' until early next week, it said.

Over the weekend, humidity levels will remain elevated "so even with slightly cooler temperatures it will not feel as though there is much of a difference,'' warned an NWS advisory.

In the meantime, an excessive heat warning will remain in effect in the San Gabriel and Santa Monica mountains in both Los Angeles and Ventura counties and the San Fernando, San Gabriel and Santa Clarita valleys until 8 p.m. Thursday, and a flash flood watch will be in effect from 2 p.m. today through this evening in the Antelope Valley and the San Gabriel Mountains, both in Los Angeles and Ventura counties.

Along the coast, a high surf advisory will be in effect until 6 p.m. Friday in both Los Angeles and Orange counties.

Thursday's weather was expected to be much like they were Wednesday, when conditions helped trigger thunderstorms, lightning strikes, mudslides, brush fires, and power outages that were still being addressed this morning.

The NWS forecast partly cloudy skies today and highs of 85 in Newport Beach; 87 in San Clemente; 88 at LAX; 93 in Laguna Beach; 94 on Mount Wilson; 95 in Avalon; 96 in Irvine and Mission Viejo; 97 in Anaheim; 99 in Yorba Linda and Palmdale; 100 in downtown L.A and Fullerton; 102 in Long Beach, Lancaster, Pasadena, San Gabriel, Burbank and Woodland Hills; and 103 in Saugus.

Friday's temperatures are expected to be several degrees lower -- 9 degrees lower in Long Beach.

The high heat coupled with the elevated humidity is prompting health concerns. Forecasters said those at greatest risk of suffering heat-related ailments were infants, the elderly, the homeless, outdoor workers, people taking part in outdoor activities in the heat, and pets without access to shade.

They urged residents to drink plenty of water; wear light-colored and lightweight clothing; stay out of the midday sun; check on neighbors and the elderly to make sure they are not being overwhelmed by the heat; and never, ever leave children, the elderly, or pets in a vehicle parked in hot weather.

Also of concern is the availability of electricity in light of heavy air conditioning use. The Los Angeles Department of Water and Power said conserving energy is especially critical between 11 a.m. and 6 p.m., when use is traditionally the highest. They urged customers to:

-- set thermostats at 78 degrees or higher;
-- limit the use of major appliances during peak hours;
-- close drapes and blinds to reduce heat;
-- turn off lights and other equipment when not in use; and
-- unplug items like cell phone chargers, DVD players and microwave ovens that can use energy even when turned off.

You can check out of a list of Beat The Heat 2015 cooling centers across the southland HERE.

Copyright 2015 FOX 11 Los Angeles : Download our mobile app for breaking news alerts or to watch FOX 11 News | Follow us on Facebook , Twitter and YouTube .