Over the course of Friday to Saturday, close to 15 million people in the Central states will be at risk from powerful thunderstorms, including tornadoes.
Warm, tranquil weather over the middle of the nation that started the week took a dramatic turn for the worst Friday into Saturday.
Thunderstorms will do more than mark an end to the buildup of warmth, cause travel delays and disruptions to outdoor plans. Severe weather will threaten lives and property from the Upper Midwest to the southern Plains. People should monitor the situation carefully.
As a powerful storm took shape Friday over the North Central states, severe thunderstorms brought a tornado outbreak centered on Iowa and Nebraska, while strong wind gusts blast parts of the High Plains.
The pattern has the potential to bring the first widespread severe weather outbreak of the autumn season and could be the most significant threat to lives and property over the Central states since May.
The first severe weather incidents developed Thursday evening, bringing 1.5 inches of rain to Baraboo, Wis. According to a 911 call center, the rain caused some minor street flooding. A little later in the evening, a 60-mph thunderstorm wind gust was recorded by an NWS spotter near Beaver Dam, Wis.
Southwest of Wisconsin, Saline County, Neb., experienced tennis ball-sized hail Thursday evening, according to a storm chaser report.
A tornado also touched down in Lancaster County, Neb., Thursday evening. A home was reportedly destroyed as the tornado rolled through. Trees and power lines were also brought down.
Thunderstorm winds gusted to an estimated 70 mph near Monroe, Iowa Friday morning.
The same system created a dust storm late Friday afternoon in Red Willow County, in the southwestern part of Nebraska, according to law enforcements.
Friday evening multiple tornadoes gripped parts of Nebraska and Iowa.
A large multi-vortex tornado was also reported Friday evening in Wayne County, Neb., the northern part of the state, by a storm chaser. A little while later, a one-mile wide tornado swept through Woodbury County, Iowa, according to emergency management.
The tornadoes continued to move northeast through the state also hitting Quimby, Iowa. They will continue to threaten areas in their path throughout the night Friday and into the morning on Saturday.
The collision of chilly air arriving from the West with warm, moist air in place over the central United States will really come together through Friday night.
According to AccuWeather.com's Severe Weather Expert Henry Margusity, "The main tornado threat will occur Friday afternoon into Friday night."
The setup could yield thunderstorms capable of producing tornadoes from southern Minnesota and southwestern Wisconsin to central and northeastern Oklahoma with Iowa at the center of the potential outbreak.
The storms could catch people off guard with rapidly changing weather conditions.
The storms could hit some communities as students are heading home from school Friday or partaking in Friday evening sporting activities, such as high school football.
In addition to the risk of tornadoes, some communities can be hit with damaging wind gusts, hail and blinding downpours capable of producing flash and urban flooding, Margusity said.
Cities that are at risk for dangerous weather conditions Friday and/or Friday night include Rochester, Minn.; Kansas City, Mo.; Wichita, Kan.; Omaha, Neb., Oklahoma City; Des Moines, Iowa; and Madison, Wis.
According to AccuWeather Enterprise Solutions' Expert Senior Meteorologist Scott Breit, "Storms over the central and southern Plains are likely to become fast-movers with an elevated risk of high winds."
A strong flow of air around the strengthening storm system will bring the potential for strong wind gusts west of the thunderstorms over the High Plains.
A few gusts could reach 70 mph in open areas from the northern Texas Panhandle and northeastern New Mexico to eastern Colorado and southwestern Nebraska Friday and Friday night.
Gusts in many of these locations will range between 40 and 60 mph, which are strong enough to cause sporadic power outages and difficult crosswinds for lightweight and high-profile vehicles.
Severe storms are likely to continue to push eastward Saturday.
During Saturday, severe weather will then focus from eastern Wisconsin and the western Lower Peninsula of Michigan to northwestern Indiana, Illinois, southeastern Missouri and Arkansas. The storms could impact additional high school games as well as some college football games.
Thunderstorms with damaging winds and blinding downpours could affect the cities of Chicago, St. Louis and Milwaukee during part of Saturday.
On the storm's colder side, a blizzard will hit parts of the northern Rockies to the northern Plains through Friday.
Meanwhile, gusty winds will also buffet Southern California Friday into Saturday, raising concerns for wildfires. Tropical Storm Karen is forecast to make landfall over the upper Gulf Coast this weekend, spreading heavy rain and gusty winds through parts of the South.
The storm forecast to bring severe weather, windswept rain and a blizzard to the Central states late this week hammered the Northwest with heavy rain and high winds this past weekend.
Roads turned into rivers in parts of the mid-Atlantic on Saturday due to flooding downpours.
Rounds of drenching showers and heavy thunderstorms will heighten the risk of flash flooding across the northeastern United States through the final weekend of July.
Tropical Storm Nida threatens to bring flooding rain to the Philippines this weekend with future impacts on China and Taiwan.
As several large fires continue to rage across the western United States, weather conditions will gradually improve for firefighting efforts this week.
Additional downpours are likely to roll across northern New Jersey and further suspend play during the late rounds at the 98th PGA Championship at Baltusrol Golf Club this weekend.
A tropical wave approaching the Caribbean Sea will attempt to reactivate the Atlantic Basin during the first week of August.
Estes Park, CO (1976)
Big Thompson River flood disaster; up to 10" of thunderstorm rains funneled into narrow canyon near Estes Park. 139 drowned, 5 missing, $35.5 million estimated damage.
1,178 "reported" tornadoes with 120 killed so far this year. Number of "actual" tornadoes probably less, but this is still one of the most active years ever (nearly half of the fatalities occurred in the Carolina outbreak of March 28th).
Los Angeles, CA (1991)
New July rainfall record of 0.17" established. The previous record was 0.15" set in July 1969.