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Pacific Storm Will lead to Heavy Rains Across Southern California and Southwest Deserts

3 months ago
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A powerful Pacific storm is set to dump the most significant rainfall since Hurricane Hilary struck Southern California in August, likely causing travel disruptions but also bringing drought relief across the Southwest deserts. The rainfall could be the precursor to a wet winter, although the strength of El Niño alone does not guarantee consistently stormy weather for the state.

Steady rains are expected across Southern California beginning Wednesday and lasting through at least Friday. The storm's center and associated cold front will remain offshore until the weekend, resulting in minimal snow for the Sierra Nevada mountain passes. While welcomed, excessive rainfall could trigger flooding, debris flows and slick roads.

Downtown Los Angeles has picked up barely over 0.4 inches of rain this fall — a fraction of the typical 2.5 inches. Drier-than-average conditions extend across Arizona and New Mexico as well. Since Hurricane Hilary dropped up to 6 inches of rain on parts of Southern California in August, seasonal rainfall has been scant at best.

But the incoming system promises to dump 2 inches or more of rain on downtown Los Angeles over the next few days. Even higher rainfall totals are expected for south and southwest-facing slopes and coastal mountain ranges. The heaviest rains should fall Thursday into early Friday around Los Angeles and late Thursday through Friday for the San Diego metro.

Gusty winds, dense fog and slick roads could plague mountain passes like the Tejon, Cajon and Interstates 5, 8 and 15. While welcome, too much rain too fast could also trigger flooding, mudslides and debris flows near recent burn scars.

As the storm pushes inland Friday into Saturday, enough Pacific moisture will reach desert areas like metro Phoenix to potentially deliver an inch of rain — rare for December. The Las Vegas Valley could see up to 0.5 inches. The rains should put a notable dent in the ongoing drought plaguing Arizona and New Mexico.

But before reaching the desert, the system will likely dump heavy snow across the central Rockies. Cold air diving southward will lower snow levels substantially. Travelers heading west across mountain passes in Colorado and Utah should prepare for wintry driving conditions.


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