Two potent storm systems are set to spin up in the coming days, one blanketing the Northern Rockies and High Plains in snow, the other lashing eastern New England with rain and wind.
The stormy duo is tangled up within a highly energized jet stream, the roaring zone of high altitude winds at the divide between cold and warm air.
The snowstorm aimed at the Northern Tier and Dakota comes barely a week and a half after parts of Montana were buried by four feet of snow.
As the jet stream dives ashore in the Pacific Northwest on Tuesday, it will drive south a disturbance at high altitudes and a pocket of frigid air. The energetic disturbance will move east, helping spin up a stormy, low-pressure zone over Minnesota.
Before the storm in Minnesota forms, an initial batch of heavy snow is possible Tuesday through Thursday morning in large parts of Montana and Wyoming, which are under winter storm watches and warnings. Six to 12 inches are possible in lower elevations, with localized 18-inch amounts up in the mountains.
As the Minnesota storm develops, it will draw north a conveyor belt of moisture that extends to the Gulf of Mexico. This moisture plume will be wrapped back into the frigid air mass crashing south, a perfect recipe for heavy snow over parts of the Dakotas, under a winter storm watch.
By Thursday evening, the quickly strengthening storm will concentrate one or more bands of heavy snow over the Dakotas, in particular eastern North Dakota. At that time, snowfall rates approaching two inches per hour are possible. Amounts will vary significantly on either side of the band, but foot-plus totals are possible within the jackpot zone and isolated amounts to 18 inches. Predicting where that bull's eye will set up at this time, however, is impossible.
The snow is likely to continue Friday afternoon and night, the southwest to northeasterly bands pivoting more southerly to northerly, combining with building 30 to 50 mph wind gusts behind the front touring near-blizzard conditions for a time.
After that, the cold-core low drifts north into Canada, with a biting northwesterly wind and occasional snow flurries spilling into Minnesota and the Upper Peninsula of Michigan in its wake.
A few rain showers may occur over the Ohio and Tennessee valleys on Saturday associated with the system's trailing front, with the front drying out and reaching the East Coast by Sunday.
Even where the front doesn't bring precipitation, its nasty drop in temperatures will spell an abrupt seasonal change.
Take Denver, for instance. Wednesday will climb to near 80 degrees. By Wednesday night, lows will dip into the 20s along with a chance of snow showers. By Friday morning, the mercury is forecast to tumble into the teens.
It's a similar story for places like Lincoln, Nebraska, Kansas City and even Des Moines, Iowa. After a Tuesday in the 70s, many spots will crash into the 40s to near 50 degrees for highs on Thursday.
On Friday, many locations in the Plains are forecast to see high temperatures 20 to 35 degrees below normal.
Nestled beneath the energetic jet stream feeding the storm in Minnesota, a fledgling low-pressure zone off the New Jersey coast is predicted to stall and bring stormy weather to eastern New England for days.
The low, currently getting its act together offshore of the Carolinas, won't be particularly intense - but it will be notably stubborn. However, the low is expected to be much farther offshore than typical high-impact New England nor'easters.
That means the bulk of the impacts will be relegated to the coastline, with brighter skies north and west. If you live west of Interstate 84, you might see a couple of gray days with periodic rain between Wednesday and late Friday. Inside of Interstate 495, however, gusty winds and about two inches of rain are possible if the storm's moisture field expands far enough west.
There's an outside chance of localized 2-to-5-inch amounts, with up to 6 inches on Nantucket, depending on the tough-to-predict specifics of the storm's "wobbling" track.
The National Hurricane Center gives this low-pressure zone a 30 percent chance of becoming a subtropical depression or storm, meaning it could acquire some tropical characteristics that might boost its rainfall. If it became a named storm, it would be called Melissa.
The long duration of the storm has raised concerns of building waves and beach erosion in coastal areas. Offshore waves could be enormous, exceeding 30 feet.
The system should finally turn off the parking brake in the wee hours Saturday, meaning conditions should finally start to clear out into the weekend for Southern New England. Unsettled conditions will persist Saturday into Sunday for coastal Maine and the New Hampshire Sea Coast as the low departs into the Canadian Maritimes.
This article was written by Matthew Cappucci, a reporter for The Washington Post.