Polar vortex set to bring rare spring snow and record colds to US this weekend

Arctic blast will come in sharp contrast to weather on west coast, where near-record heat is expected to continue

A late-season polar vortex is expected to bring rare spring snow and record colds across much of northeast US for the Mother's Day weekend.

The National Weather Service has freeze watches and warnings as a low-pressure system pulls frigid Canadian air south into the Mid-Atlantic and Gulf of Main.

The polar vortex is expected to bring rain, thunderstorms, snow and record low temperatures as far south as the Gulf Coast.

National Weather Service meteorologist Peter Mullinax wrote in his short-range forecast that the arctic blast will make for a chilly and blustery weekend for most eastern regions, with measurable snowfall possible in the Northeast and Great Lake.

Snowfall is expected to begin over parts of the Great Lakes on Friday, into the Ohio Valley by the evening and overnight in central Appalachia and parts of the Northeast towards New England by Saturday.

"Numerous freeze watches and warnings have been posted from the Midwest to the Northeast with record low temperatures possible over the weekend, most notably Saturday morning," Mr Mullinax said.

"Snow could fall heavily at times with several inches of accumulating snowfall possible in the northern and central Appalachians. Temperatures will moderate slightly but remain well below normal across much of the eastern US on Mother's Day."

The record low temperatures could stretch from Caribou, Main, in the north to the Texas Lower Rio Grande Valley in the south.

The polar vortex first came to prominence after terrorising the northeast during the North American cold wave in 2013, before returning in early 2019.

It is a mass of low-pressure cold air that is constantly circulating above the Arctic by a jet stream of wind, which can drop south into North America, Europe and Asia when that jet stream weakens.

Spring snow is extremely rare, with no measurable May snowfall in Massachusetts since 2002 and none in Boston since 1997, according to National Weather Service meteorologist Alan Dunham.

Mr Dunham told the Associated Press that forecasts predicted as much as two inches in the Berkshire Mountains in western Massachusetts, an inch in southern New Hampshire and western Connecticut, and rain with snowflakes in Boston.

While upstate New York could see an inch of snow, New York City and the Hudson River valley would mostly see rain.

On the west coast, meanwhile, near-record heat conditions are expected to continue.