The polar vortex is running late this year, but it's coming to hit the eastern U.S. for Mother's Day weekend, and setting the stage for a possible historic May snowstorm in the Northeast. The National Weather Service's (NWS) Weather Prediction Center (WPC) has announced that an "unusual weather pattern evolving across North America," including an "unusually cold" air mass from eastern Canada, is making a late-season snowstorm "increasingly likely" for the interior Northeast.
The cold air mass will cause rain from a system moving out of the Tennessee Valley to change to wet snow that could hit hard in the central Appalachians Friday. The storm system will then intensify further as it skirts the New England coast, according to the WPC.
"The potential for heavy snow over portions of the higher terrain of northern New England Friday into Saturday is increasing," the WPC said. "May daily snowfall records may be shattered, with several inches of snow possible."
In the worst case scenario, these storms could "shatter" records for May snowstorms. "Although daily snow in May across New England is not extremely rare, daily snowfall records for the month are possible," the WPC said.
"As colder air rushes in behind the front Friday evening, there will be a transition from rain to snow showers along the Allegheny Front with minor snow accumulations likely," forecasters said. "Further east, not expecting accumulating snow, however some wet flakes mixing in remains a possibility along and west of the Blue Ridge."
Even if no snow actually falls, the eastern third of the country will get record-low temperatures, especially in the Great Lakes and the Northeast. Frost advisories, freeze warnings, and freeze watches already stretch across the Great Lakes into the Ohio River Valley and high-elevation locations in the Southeast.
“Over some areas, this cold surge would lead to a late frost/freeze where the growing season has already started,” the NWS said.
However, the exact opposite is happening in the West Coast. Southern California, the Desert Southwest and the southern Rockies are expected to face a record heatwave. There are heat advisories in effect in the region and fires are expected in several areas. Triple-digit temperatures on Thursday could hit in Southern California, southern Arizona, southern New Mexico and far west Texas.