A storm system digging into the West will bring unseasonably early snowfall to the mountains of southern California before swinging east and bringing the threat of severe weather to parts of the Plains.

California Snow

A cold area of low pressure in the upper atmosphere will continue diving south through the West Coast, reaching southern California Wednesday evening before turning northeastward across the Four Corners region Thursday and into the Northern Plains on Friday.

The Pacific Northwest has already seen rain and high-elevation snow from this feature. This activity will dive south into California and Nevada on Wednesday, bringing rain to the lower elevations of those states.
For Los Angeles, this could become the first measurable precipitation (.01 inch of rain or more) since July 26.

The cold air in the upper atmosphere will bring snow to the Sierra Nevada, generally above 6,000 feet. Even farther south, the mountains of southern California could see some rare early-October snowfall.

Elevations above 6,000 feet in western San Bernardino County and western Riverside County could see a few inches of the white stuff Wednesday into Wednesday night as the system dives in. At Big Bear Lake, where official weather recordkeeping began in 1960, the earliest 1-inch snowfall on record was Oct. 10 back in 1985. If at least an inch of snow falls Wednesday, that record will be broken by a day.

Rockies Snow, Wind

As the storm makes a hard left turn and swings northeast toward the Rockies, it will bring snow to higher mountain elevations of Utah, Colorado, Wyoming, and possibly southern Montana.

Low pressure will then intensify over the Plains and track roughly from eastern Colorado northeast through the Dakotas. While this storm track is very similar to Winter Storm Atlas, this system will not draw down as much cold air from Canada.

As a result, snow will have a difficult time reaching the lower elevations (say, below 6,000 feet) east of the Rockies. Places such as Casper, Wyo., and Rapid City, S.D., which saw crippling snowfall during Atlas, will likely see rain or a rain/snow mix from this storm system.

The rain, falling on areas that saw up to 5 feet of snow from Atlas, could potentially lead to some minor flooding problems in eastern Wyoming and western South Dakota.

Despite the lower threat of wintry weather for many, winds will still be a factor due to the strength of the low-pressure system. Sustained winds greater than 30 mph may occur in many areas just east of the Rockies. These blustery winds will blow from the south as the storm approaches, and then from the north or northwest as the storm passes by.