Snowy South, Fiery West: Whats Happened to our Moisture? [View all]

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https://www.wunderground.com/cat6/snowy-south-fiery-west-whats-happened-our-moisture
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A swath of high-impact snowfall—in some places, among the heaviest ever observed—made its way from South Texas to Atlanta on Friday, en route to the big cities of the Northeast U.S. (see below). Meanwhile, massive wildfires continued to scorch the landscape of Southern California, raging at unprecedented scope for December. It’s an odd juxtaposition, driven by a highly amplified weather pattern. Winds at the jet-stream level on Friday were blowing from the Canadian Arctic south across the Great Plains all the way to Mexico (see Figure 2).

Perhaps surprisingly, this pattern hasn’t produced many U.S. record lows, and few are in the offing for the next few days. The strong northerly jet hasn’t managed to pull a truly bitter Arctic air mass into the 48 states. Instead, the central and eastern U.S. are heading into a few days of consistent but less-than-brutal cold, while very mild, dry air continues to blow offshore across coastal California, stoking the fire threat.

Last month was the 19th driest November in U.S. records dating back to 1895. Outside of the Northwest and the eastern Great Lakes, most of the contiguous U.S. was drier than average (see Figure 3 below), with large swaths of “much below average” precipitation. A mere 0.08” of moisture was observed in Lincoln, NE, from October 15 through December 7; it’s the least precipitation on record for that interval, in data going back to 1887 (the runner-up is 0.23” in 1976).

Over the two weeks ending December 5, the U.S. Drought Monitor showed a dramatic leap in drought coverage. The percentage of the nation experiencing at least some level of drought has vaulted from 15% to 24%. Leaps of this magnitude do happen, but they’re more common in spring and summer, when high temperatures, intense sunshine, and low humidity can quickly dry out the landscape.