The eastern U.S. is now living in a state of permanent Smarch while the West has fast-forwarded through spring.
Temperatures are expected to plunge on Friday to well below normal, and cold weather records could fall in the Midwest. The cold air will also reach the East Coast, trailing a storm, which could create the rare site of snow on Washington, D.C.’s cherry blossoms this weekend. Yes, in April.
In the West, it’s a totally different story. An atmospheric river will plow into California, flush with precipitation. But because the storm is coming unusually late in the season, it’s bringing unusually warm moisture, meaning that rather than provided much-needed snow, it will dump rain and actually diminish the state’s already-limited snowpack.
So yeah, wtf is going on?
It turns out it’s everybody favorite weather phenomenon, the polar vortex, is playing a role. Much of the Smarch-like weather we’ve been dealing with the eastern U.S. can be tied back to a disruption in the polar vortex in February that just hasn’t really let go according to Judah Cohen, the director of seasonal forecasting for Atmospheric and Environmental Research.
The polar vortex is a phenomenon that sits mainly in the stratosphere, the layer above the our part of the atmosphere where storms and other weather systems form. When it gets disrupted, it can cause cold air normally trapped in the Arctic to leak into the lower latitudes. One such disruption happened in December, which brought us a bad presidential tweet and record low temperatures and a bomb cyclone. But the disruption in February was even more intense, and Cohen said it’s still with us today.
“We’re getting the last of these tentacles [of cold air] from February,” he told Earther. “It could be the last hoorah, though there’s a suggestion there could be one more late in the next week.”
Cohen’s research has pointed toward the rapid warming in the Arctic as a driver of the recent increase in polar vortex intrusions. (This research is cutting edge, and still being debated.) Atmospheric patterns in the tropics can also play a role in messing up the polar vortex, and Cohen said it’s possible the push and pull on both ends of the atmosphere could be why the February polar vortex disruption was so intense.
Like other polar vortex intrusions in this and other winters, the cold air is also being hermetically sealed off in the eastern U.S., leaving the West to roast. An Pineapple Express atmospheric river of moist, tropical air will help warm things up further. According to a tweet from meteorologist Ryan Maue, overnight lows in California could be record warm for this time of year, on the same day the Midwest sets record lows.
In the east, we’re looking at snow as far south as the Mid-Atlantic this weekend. While totals are still very much up in the air, it’s possible flakes will fly in Washington, D.C. making for some very cool pictures on the Mall where cherry blossoms are in full bloom. The West, meanwhile, can expect rain on snow in the Sierras. Flood watches have been posted ahead of the storm, with the National Weather Service warning residents to “PREPARE NOW by clearing drainages and ditches of debris in preparation for increased water flows.”
This is bad news for both regions. In the east, the chill could hurt crops. The pattern this year is somewhat consistent with research showing spring is coming earlier in terms of when plants are putting out their first leaves, but that the last freeze isn’t moving up as fast.
“While the physical mechanisms for this trend are still under investigation, it poses substantial risks for farmers as plants are more vulnerable for damage given a larger growing period between the first spring onset and the last freeze,” Zack Labe, a PhD candidate at the University of California, Irvine who has been studying this trend, told Earther.
In the West, the rain on snow means that snowpack will shrink, cutting into a natural reservoir California and other western states rely on for water in the dry summer. So yeah, this sucks all around.
As an East Coaster, I’d like to give Cohen the last word, which reflects how all of us feel at this point:
“I’m a diehard snow fan and I’m following other people who love snow. Even really diehard snow fans say enough is enough, bring on spring.”