As we have seen multiple times this summer, during the middle of this week thunderstorms will fire on the northern rim of heat from the northern Plains to northern New England.
Wednesday, the area at risk from the storms will span North Dakota eastward to northern upstate New York and Maine.
Cities in the path of the storms include Fargo, N.D., Duluth, Minn., Thunder Bay and Ottawa, Ontario, Montreal, Quebec, Plattsburgh, N.Y., Burlington, Vt., and Caribou, Maine.
The greatest risks from the storms will be localized damaging wind gusts and frequent lightning strikes.
South of this area, within the vast area of heat and high humidity, very widely separated thunderstorms can occur through the balance of the week. However, most of these storms will occur during the late afternoon and evening hours with blinding downpours and a few lightning strikes, being their most significant characteristics.
Late in the week, a shift in steering winds high in the atmosphere will allow a broad zone of thunderstorms to sweep southeastward across the Great Lakes into more of New England and the mid-Atlantic. The late-week storms will not only break the heat wave but can also bring the risk of severe weather to more locations than the midweek storms.