Weekly newspaper of Three Rivers, California, and Sequoia-Kings Canyon National Parks

Another ho-hum midwinter day in Three Rivers.

Remnants of polar vortex bring Arctic air to California

John Elliott


While nearly two-thirds of the continental U.S. was hunkered down to withstand record-breaking temperatures and wind chill, Kaweah Country remained comfortably mild and dry after last week’s rainfall. That bitter Arctic chill was blamed for at least a dozen deaths in the Midwest. 
During this frigid weather, meteorologists are constantly using textbooks to define these not-so-common weather-makers. This week, it was polar vortex; that last really pronounced one that affected the Midwest occurred in 1985. 
A polar vortex is an upper level low-pressure area lying near the Earth’s poles — the North and South poles. When the polar vortex is strong, there is a single jet stream well constrained near the polar front of frigid Arctic air.
During late winter, large fragments of the vortex can be diverted into the lower latitudes and are often associated with La Nina climate events. This past week, atmospheric conditions lined up to produce a dip in the vortex-influenced jet stream and that brought Arctic cold deep into the nation’s mid-section. 
In Wisconsin, some areas recorded temperatures minus 30 degrees with wind chills of 55 below zero. Northern Minnesota shivered through record wind chills of -70 F. Chicago checked in with 21 below and that broke a long-standing record for the Windy City. 
Polar vortex comes west
Some remnants of the latest polar vortex are expected to be felt in the Pacific Northwest and the upper third of California from Saturday to Tuesday. Snow levels in Humboldt and Shasta counties could fall below 2,000 feet as a strong storm system will bring heavy rain to most of California by Saturday and persist into next week.
The cold air won’t make it too far south and should stay north of the Bay Area. The Sierra Nevada region from Yosemite to Lodgepole is expecting two to four feet of new snow, especially at elevations above 7,000 feet.
In Three Rivers, all that wet weather is expected to amount to about two inches of rainfall by Monday night. As of the end of January, Three Rivers had recorded more than 7.50 inches of rainfall at 1,000 feet. 
That total could easily eclipse 10 inches by Monday. One year ago, the entire region was in a deepening drought. The 2018 total at this time in Three Rivers was 4.02 inches, and it didn’t rain another drop until February 22. The total for the entire 2017-18 season was 13.03 inches with almost all of that falling in March.
Current season
The season total should surpass last year by mid-February and feel more like a normal 20-inch rainfall season with each passing storm system.
High temperatures for the next seven days will not make it out of the 50s, and that means powdery snow in the high country adding to a pack above 7,000 feet that could reach five or six feet after the current series of storms.