Dangerous, damaging and disruptive thunderstorms are forecast to shift from the northern Plains to the Great Lakes and interior Northeast this weekend as a searing heat wave expands across the country.
The storms will fire on the northern rim of the expanding and strengthening area of intense heat at the same time that a disturbance is moving eastward across the southern tier of Canada. A stream of strong winds will be present overhead, which will also help to fuel the gusty nature of the storms and their sometimes fast forward speed.
High-speed winds tore through the town of Churchs Ferry, North Dakota, around 4:30 p.m. CDT on Friday, the National Weather Service Storm Prediction Center reporting winds from 58 to 101 mph. For reference of how powerful winds of that speed are, an EF1 tornado has wind speeds from 86 to 110 mph.
"The storms from the Dakotas to Minnesota, northwestern Wisconsin and part of the Upper Peninsula of Michigan as well as southern Manitoba and part of northwestern Ontario may bring the full spectrum of severe weather," according to AccuWeather Senior Meteorologist Brett Anderson.
The storms have the potential to bring large hail, flash flooding, frequent lightning strikes and a few isolated tornadoes.
"The most far-reaching effect could end up being high wind gusts," Anderson said.
Thunderstorms are forecast evolve into a large and fast-moving complex that produces a swath of damaging winds and torrential rain over hundreds of miles along the northern tier of the U.S. from Friday night to Saturday morning. When complexes behave in this manner and travel 250 to 400 miles or more, they may be dubbed a derecho. Widespread power outages can occur with a derecho.
Cities at risk for the violent storms include Fargo, Grand Forks and Bismarck, North Dakota; Minneapolis and Duluth, Minnesota; Eau Claire, Wisconsin; Winnipeg, Manitoba; and Aberdeen, South Dakota; into the start of the weekend.
During the midday hours on Saturday, the complex of storms will either continue to move along or fade out.
Regardless, new storms are expected to erupt and become severe over portions of the central Plains and western and northern Great Lakes region during the afternoon and evening hours on Saturday.
Even though the risk of tornadoes is likely to be much lower, occasionally, severe thunderstorms could produce a brief tornado. The National Weather Service in Buffalo, New York, confirmed that an EF1 tornado caused damage in Portland, New York, on Thursday evening. The storm destroyed a barn.
"The main threats with Saturday's storms are likely to be from strong wind gusts, flash flooding, hail and frequent lightning strikes," Anderson said.
An AccuWeather Local StormMax™ of 80 mph is anticipated with Saturday's storms.
The storms could sag as far south as Des Moines, Iowa, but storms are likely to cause trouble in Milwaukee, Green Bay and Madison, Wisconsin; Mason City and Cedar Rapids, Iowa; and Sault Ste. Marie and Houghton Lake, Michigan.
Severe thunderstorms will be less widespread on Sunday when compared to Friday night and Saturday, but storms from the Ohio Valley to the eastern Great Lakes, central Appalachians, northern New England and part of southeastern Canada are likely to be heavy, gusty and severe at the local level at the close of the weekend.
On a positive note, assuming the storms don't bring damage to particular communities, drenching downpours may help to water some fields, orchards, vineyards, lawns and backyard gardens along the way. More than 51% of the country is facing at least abnormally dry to drought conditions as of July 14, according to the U.S. Drought Monitor.
The storms with the cool shots of air and rain can also bring relief to some areas that will be sweltering away in the throes of a midsummer heat wave that will bring highs approaching 100 F and put long-standing records dating back to the turn of the 20th century in jeopardy.
Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.