July 29--Flash flood warnings were issued for parts of inland Los Angeles and San Bernardino counties on Wednesday as intense thunder and lightning storms moved into the high desert.
Pockets of heavy rain were reported in parts of the Antelope Valley as well as the Apple and Lucerne valleys. A severe thunderstorm warning was issued for the Hemet and Banning areas.
The National Weather Service said the rains were powerful enough to produce localized flooding.
More of the same is expected through the weekend as a monsoonal flow moves into the area.
Parts of Northern California were experiencing hot conditions. As of noon Wednesday, Sacramento hit 100 degrees and Redding hit 106.
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Here's a breakdown of what to expect.
Heat
Temperatures will rise into the 90s and 100s through the weekend, along with a major rise in humidity.
"The combination of high temperatures and increasing humidity may cause some areas to approach excessive heat levels, especially Thursday and Friday. During this time, people at risk of heat-related illness should be extremely cautious and seek shelter in air conditioning if possible," the National Weather Service said in a bulletin.
Storms
The thunderstorms are most likely to develop in mountain, inland valley and desert areas, but coastal areas might see them as well, according to the NWS.
"Any storms that develop by Thursday will be capable of producing heavy downpours, dangerous cloud-to-ground lightning, strong gusty winds and flash flooding," the NWS said.
Health Risks
The heat and humidity place frail people at risk, especially during the peak days of Thursday and Friday.
"During this time, people at risk of heat-related illness should be extremely cautious and seek shelter in air conditioning if possible," the NWS says.
El Niink
Climatologists believe the rain is the result of El Nia weather phenomenon characterized by the warming of Pacific Ocean waters west of Peru that causes changes in the atmosphere and can dramatically alter weather worldwide.
Last week's destructive rains came from remnants of Hurricane Dolores. Warmer ocean temperatures allowed the former hurricane to make landfall in California with more moisture and strength than if the ocean were as cool as it normally is.
The source of this week's expected storms is a monsoonal system centered over Arizona and Texas via Mexico, forecasters said.
The unusually warm waters in the Pacific are behaving like a siren for hurricanes off Mexico like Dolores, which drew humid air and punishing thunderstorms north to California, where they slammed head-on with the state's drought conditions, forecasters say.
Long-term forecast
For now, there's only an equal chance of a wetter-than-average rainy season north of San Francisco, where much of the state's water supply is collected and stored in giant reservoirs. California needs rain and snow there. Snow slowly melting from the mountains is essential to recharging the reservoirs later in the spring.
A typical El Nienerally dumps heavy rain only on Southern California. But the most powerful El Nion record, 1982-83 and 1997-98, were strong enough to send dramatic storms over Northern California as well.
This year's El Niould be as strong as the 1997-98 El Nir stronger. On July 22, a key benchmark location in the Pacific Ocean was 2.88 degrees above average. That's similar to the temperature reading July 23, 1997, which was 3.06 degrees above average.
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UPDATED
1:56 p.m.: This article was updated with Northern California temperatures.
1:42 p.m.: This article was updated with an inland flood warning.
This article originally published at 7:11 a.m.
