(CNN) — A new severe storm outbreak with potential intense tornadoes and damaging wind gusts up to 90 mphis set to slam the central US Friday, hitting areas already battered by a multi-day onslaught of twisters, massive hail and historic flooding.
The first storms are underway and they will only grow more expansive through the afternoon. Tornado watches are in effect for nearly 14 million from Wisconsin to northern and western Oklahoma through early evening.
The biggest threat of tornadoes, some of which could be EF3 or stronger, is centered in western Wisconsin, southeastern Minnesota, eastern Iowa and northwest Illinois. The storms will also be capable of unleashing widespread destructive winds and hail from Oklahoma City to Green Bay, Wisconsin, Friday afternoon and evening.
The threat comes after nearly four dozen tornado reports and over 350 reports of hail — some as large as softballs — from Texas to the Great Lakes since Monday.
Ingredients align for a severe storm outbreak
A fresh surge of jet stream energy arriving in the central US on Friday will tap into Gulf moisture, likely igniting a severe storm outbreak, meaning there will be numerous storms.
A Level 4 of 5 risk of severe thunderstorms is in place from northwest Oklahoma to western Missouri, including Kansas City and Wichita, Kansas. Giant hail up to near the size of softballs and destructive wind gusts over 80 mph are the biggest threats in this area, but isolated tornadoes are possible.
Powerful storms are also expected in a Level 3 of 5 risk area that extends as far north and east as eastern Iowa, Wisconsin and Illinois, including St. Louis, Chicago and Madison, Wisconsin. This also includes the area with the biggest concern for intense tornadoes — EF3 or stronger — from La Crosse, Wisconsin, to Davenport, Iowa and Moline, Illinois.
The first batch of storms erupting in the western part of the threat zone are the ones most likely to spin up tornadoes and unleash the biggest hail, which could total vehicles, shatter windows and damage roofs.
Widespread damaging wind gusts of 60 mph to 90 mph will be capable of uprooting trees and knocking out power when they become the main threat by late afternoon and evening as thunderstorms race east. Tornadoes could also still spin up along the leading edge of these storms.
The storms could also produce flash flooding, including in already-soaked Chicago and Milwaukee, where there have been dozens of water rescues in recent days.
This system could produce one final burst of severe storms with a threat of strong winds Saturday in the upper Ohio Valley. The storm-weary central US will finally get a breather starting Sunday as a welcome change in weather pattern ushers in cooler temperatures.
Great Lakes brace for more flooding
Friday’s storms arrive as parts of the Great Lakes deal with significant flooding after repeated rounds of rain this week. The region is coming off one of its wettest starts to spring on record, combined with snowmelt from a very active winter.
Rivers in Michigan and Wisconsin have already hit major or record flood levels in over 20 locations.
The Wolf River in Wisconsin was nearly a foot above its record flood stage on Friday morning, a level that puts many streets in the village of Shiocton under as much as a foot of water. Shiocton officials said “a majority of the streets in the village limits are impassable” as of Friday morning and urged people to stay out after ordering evacuations on Wednesday.
Residents in low-lying areas of neighboring Waupaca County have also been advised to evacuate due to the rising floodwaters. The city of New London, which straddles Waupaca and Outagamie counties, urgently requested volunteers for sandbagging efforts Friday morning.
In Michigan, officials are closely monitoring several dams under stress from high water.
A long stretch of the Muskegon River remained in major flood on Friday morning, with some locations nearing a crest while others were still rising. The flooding forced mandatory evacuations for “anyone remaining in the floodplain below Croton Dam” in Newaygo County, the county’s emergency services said.
In Evart, Michigan, the river was nearing a crest on Friday morning after it forced rescues the day before when water began to impact homes, according to the Evart Fire Department.
Residents near and north of the Cheboygan dam complex were told to be ready to evacuate on Thursday morning as water levels continued to rise, reaching 5.16 inches below the top of the dam as of Friday morning. An evacuation order would be triggered if water reaches 1 inch below the top of the dam, a news release from the Michigan Department of Natural Resources states.
Crews have been working around the clock to protect the dam, deploying pumps and sandbags and making alterations to increase water flow.
Dams across Cheboygan County are “at capacity,” county Emergency Management Director Lt. Jeremy Runstrom told CNN on Wednesday.
This includes the Alverno Dam, which officials are also attempting to defend from the deluge. Its integrity is particularly significant because failure would send a torrent of water downstream to the Cheboygan complex, Michigan State Rep. Cam Cavitt told CNN.
“If that dam would go, it would take the Cheboygan dam with it,” he said Wednesday.
On Thursday afternoon, residents living along a roughly seven-mile stretch of river between the two dams were advised to prepare and pack for possible evacuation.
In Antrim County, Michigan, officials have also advised residents and businesses downstream of the Bellaire Dam to prepare for possible evacuation. Water levels were stable and trending down Friday morning after rising to within 12 inches of the top of the dam Tuesday.
A flash flood watch is in effect for the potential failure of the Hesperia Dam in west-central Michigan. Water levels were trending down, the Hesperia Area Fire Department said early Friday morning, but noted residents downstream should “remain alert and have an evacuation plan in place should conditions change.”
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