Unseasonably cold

A large, powerful high pressure system originating in the
Eastern or Western Pacific and stretching to the
North Pole is required to displace the pocket of cold air.

""The polar vortex will drop into Ontario during the first weekend in April," according to AccuWeather Long-Range Meteorologist Joe Lundberg.

This means arctic air will have a direct path into the Midwest.

"From Sunday, April 3, through the following week, most of, if not all, days will bring below-average temperatures from the northern Plains to the mid-Atlantic coast," Lundberg said. "We expect nighttime temperatures to drop to freezing as far south as the Tennessee Valley."

Temperatures will average 15-30 degrees Fahrenheit below normal with the core of the cold air directed at the North Central states. Normal highs during the first week of April are in the lower to middle 50s in Minneapolis, Chicago and Detroit and in the 60s from Kansas City, Missouri, to Nashville and Cincinnati.

"The intense cold could impact play for opening day MLB games in Pittsburgh and Kansas City, Missouri, on Sunday, as well as games elsewhere in the Midwest and Northeast on Monday," according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok."

http://www.accuweather.com/en/weather-news/polar-vortex-to-plunge-cold-into-midwest-east-us-early-april/56265180