Overview

With a Pacific low pumping moisture through the Southwest United States, we are seeing ongoing valley rain and mountain snow through California, Arizona, Nevada and Utah. The low pressure center is still sitting out in the Pacific Ocean and is expected to move onshore over the next 24 hours. It will bring heavy rain across Southern California. A trough in the jet stream will dive south-bound, helping to energize the thunderstorms and pump in the moisture.

Forecast

The storm will move farther east this afternoon (Monday) and bring a chance of rain to Las Vegas as well.  Not only rain for the exceptionally dry Las Vegas area, but Los Angeles and San Diego will be a bit soggy. Don’t be surprised if you hear a rumble of thunder in the air, as thunderstorms are possible from the San Francisco Bay Area all the way south into Southern California!

Mountain snow will develop into Nevada, Utah, the fringes of Northern Arizona, and New Mexico, preceding an effective warm front.

Tonight through Tuesday is where Utah and Colorado are expected to see their most snow.

By Tuesday Night, most of the storm will be moving out of the Rockies. It will develop into a big winter storm, forecast to drop heavy snow amounts from the Plains to the Midwest.

Alerts

At this time, winter storm warnings are in effect for the Ventura, Santa Barbara, San Bernardino, and the Riverside Mountains where 4″-8″ of snow is likely and up to 12″-18″ are possible in localized areas. Winter alerts extend across Nevada, Utah, Colorado and New Mexico.

A very small risk for flooding is forecast for parts of Southern California.  This is due mainly from burn scars left from wildfires this summer and fall.

Amounts

In California, snow could stack upwards of 2″-4″ over 3500 ft in Kern County.  In the Sierras, 10″-14″ over 4,000 ft are possible, while over 7,000 ft 18″-24″ will accumulate.  In Nevada, 1″-3″ of snow is likely in the lowest of elevations while a general range of 2″-5″. Some of the tallest peaks may top out close to 10″.

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