While much of the rest of the country shivers under a historic cold snap, Southern California has entered into another week of unseasonably toasty temperatures. Are the two phenomena related?
Meteorologists say yes and no.
The so-called "polar vortex" that has descended from Canada and plunged much of the Midwest and South into single-digit and negative temperatures is a separate weather pattern from the system that has kept Southern California relatively warm for the past few weeks, says Eric Boldt, a National Weather Service meteorologist based in Oxnard.
Boldt says the culprit in Southern California's balmy winter so far is a high pressure system that has stalled over the Eastern Pacific and has been deflecting cooler, wetter weather to other parts of the country.
"If you can picture it, in the Eastern Pacific Ocean, we have high pressure that's blocking all these storms, and they go right over that high pressure system and shift more to the east of us," Boldt said. "So they get storm after storm reinforcing cold air coming down from basically the Arctic area and the colder Canadian areas, right into the central part of the country."
Boldt says the Pacific high pressure system has been directing winds from the Central Basin of Utah and Nevada to blow down through the mountains ringing Southern California. The winds heat up as they barrel their way offshore.
"We're stuck with this high pressure system, so that doesn't allow low pressure systems to impact us," Boldt said. "We have had a couple events in December where these low pressure systems came down California, and that gave us a little bit of light rain, and that's been about it for our rainfall so far this winter."
Boldt says the winter heat wave is likely to persist for the next several days.