Severe Storms Target St. Lawrence Valley & Upper Midwest.
A pair of cold fronts, one crossing the Great Lakes and a second pushing through the northern Plains, will spark two areas of concern for severe thunderstorms Sunday afternoon and evening.
Moderate instability and moisture are surging northward through the Ohio Valley and eastern Great Lakes Sunday in response to a cold front pushing across eastern Ontario and lower Michigan. Scattered areas of thunderstorms are expected to develop Sunday afternoon out ahead of the front from western New England down to the Ohio Valley. In upstate New York and through the St. Lawrence Valley, moderate instability will combined with modest wind shear and lift from the cold front to produce an elevated threat for severe thunderstorms. Consequently, cities from Burlington, Vermont up toward Montreal, Quebec are at risk for a round of severe weather with the primary threats being damaging winds and hail.
Across the Ohio Valley and western Pennsylvania, weak winds aloft will help to mitigate the overall severe threat, but a few stronger storms with gusty winds are possible.
Similarly to the Northeast, the atmosphere across the Upper Midwest will become increasingly unstable Sunday afternoon as temperatures warm and moisture gets drawn northward ahead of a cold front that will be moving through northern High Plains. Scattered strong to severe storms are expected to develop during the late afternoon hours across eastern North Dakota and spread eastward through northern Minnesota during the evening hours. Damaging wind and large hail are the primary concerns with storms that reach severe thresholds.
Later at night, the severe threat will diminish; however, a line of gustier storms could still threaten cities like Duluth and possibly Minneapolis, Minnesota after midnight.