The first significant rain and snow event of the season has begun in Southern California and the Southwest, and while it will bring relief from dry conditions, there could also be localized flash flooding.
Asouthward plunge of the jet stream along the West Coast and an upper-level area of low pressure will continue to bring the chance for precipitation to the Southwest through Thursday.
Locally heavy rain will increase the risk of flooding at times and the higher elevations will see snow pile up.
Some roads were flooded in Southern California on Tuesday and 2.32 inches of rain was measure in Valley Center, California, as of early Wednesday.
Vehicles were reported stuck due to flooding along state Route 62 in the Mojave Desert early Wednesday and motorists were stranded along Highway 177 north of Desert Center, California.
Wet Forecast
Rain will continue in parts of Southern California and much of the Southwest through at least Wednesday night. Snow will fall in the higher elevations of the Sierra Nevada and Rockies.
The chance for rain and higher-elevation snow will continue through Thursday in much of the Four Corners region.
In Southern California, additional rainfall of around an inch or so are expected below snow level (about 6,000 feet in elevation) in the far southwestern portion of the state, including the San Diego area.
Additional rainfall of 1 to 3 inches are forecast in parts of Arizona through Thursday, with some locally higher amounts possible in the mountains north and east of Phoenix. The Phoenix Valley is expected to pick up double or more its average November monthly rainfall (0.65 inches) in about 48 hours.
Precipitation will be spread out over several days, so widespread flash flooding is less likely, but could occur in some heavier downpours.
Flash flood watches have been issued by the National Weather Service from extreme Southern California into much of Arizona, southern Utah and extreme southern Nevada. Flash flooding is possible in these areas, particularly in normally dry washes and urban areas. Debris flows are also possible near steep terrain or below recent burn areas.
Several inches of snow will also pile up in the Sierra, with more than a foot possible in the higher elevations of southern Utah, southern Colorado, Arizona and northern New Mexico.
Winter storm warnings have been posted by the National Weather Service for the southern Sierra, the San Bernardino and Riverside County mountains, parts of extreme southern Nevada, southern Utah, southern Wyoming and western Colorado.
First Significant Rain and Snow of the Season
This is the first notable precipitation in this region so far this wet season, which typically begins in November and lasts through April.
More than 80% of California is at least abnormally dry, according to the latest U.S. Drought Monitor, since precipitation has not fallen this wet season. This is a big jump from Nov. 5, when less than 18% of the Golden State experienced abnormally dry conditions.
Los Angeles and San Diego average around an inch of rainfall from Oct. 1 through Nov. 15, but they did not receive any rain during that period. It has been the eighth-driest start to the water year in downtown San Francisco, where only 0.03 inches have been measured, and it does not appear much, if any, rain will fall there with this upcoming system.
Drought conditions have also developed and expanded in the Four Corners region since late summer due to a relatively dry monsoon season in Arizona and New Mexico, according to the U.S. Drought Monitor.
Drought conditions cover about a quarter of the West.
The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.
The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.
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