Dangerous severe weather threat packing tornadoes and large hail looms over central US
An 800,000-square-mile swath of the central United States will be at risk for rounds of severe thunderstorms, including the potential for tornadoes, into early next week.
"Tornado Alley is certainly about to wake up!" AccuWeather Extreme Meteorologist Reed Timmer said, describing the severe weather outlook as the worst setup he's seen in years.
Ahead of the main outbreak of severe weather, a narrow band of severe thunderstorms sliced through Iowa, Illinois, Indiana and Ohio Thursday into Thursday night. There were reports of hail as large as tennis balls just west of Chicago. Flash flooding and winds up to 78 mph were reported in Iowa.
A shelf cloud on the leading edge of a severe thunderstorm near Cayuga, Indiana, on Thursday afternoon. (Twitter/Kyle Lockhart/@eas3964)
Over 40,000 were left without power around Indianapolis after severe storms raced through the city on Thursday afternoon. Another severe storm brought hail larger than golf balls to areas from Danille, Illinois, through Rosedale, Indiana.
Many more states will be at risk into this weekend.
This several day outbreak will put at least 18 different states in the path of dangerous weather in the coming days.
On Tuesday, the National Weather Service's Storm Prediction Center (SPC) highlighted a risk area for severe weather every day of their eight-day outlook. This is the first time that has happened since that SPC product became operational in 2007, according to Harold Brooks, a senior scientist of the Forecast Research and Development Division at the National Severe Storms Laboratory.
AccuWeather estimates that about 44 million people live in the risk zone for severe thunderstorms from Friday to Sunday.
An active Pacific Ocean storm train will set the severe weather outbreak into motion. At the same time, warmth and moisture are forecast to build over the Plains and Mississippi Valley. A strong jet stream will stir the pot for severe weather soon after the storms cross the Rockies and come in contact with the warm and humid air.
The rounds of severe weather are coming at a time when travel and graduations begin to ramp up. Whether staying at home or on the road, be sure to stay up to date on the severe weather potential.
The tornado and high wind risk is likely to extend to after dark, which will add to the danger. It is possible that a few of the tornadoes may be large, violent and on the ground for more than a few minutes.
Large hailstones likely to be produced during the strongest storms can cause serious injury, kill livestock and cause substantial property damage.
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Storms to erupt on High Plains into Friday night
"Heavy to locally severe storms may erupt near the northern boundary of warm air over northern Iowa and southern Minnesota into Friday night," according to AccuWeather Meteorologist Jake Sojda.
The first widespread round of severe weather, which may evolve into a significant outbreak, is forecast to begin over the High Plains from western Texas to southern South Dakota and the southeastern corner of Wyoming. There may be a large break in severe activity centered over Kansas, where only a few severe storms may erupt.
The storms Friday evening will erupt along the boundary separating dry air to the west and humid air to the east, otherwise known as a dry line.
These storms have the potential to bring very large hail and tornadoes, as well as wind gusts to 80 mph and highly localized flash flooding.
There is the potential for some of the tornadoes to be strong and on the ground for more than a few minutes. The area at greatest risk for multiple tornadoes may be in western and central Nebraska during Friday evening.
Cities in the first wave of severe weather late Friday include Midland, Texas; Dodge City and Goodland, Kansas; North Platte, Grand Island and Lincoln, Nebraska; Sterling, Colorado; and Sioux Falls, South Dakota.
Clusters of heavy to severe storms are likely to continue, while progressing slowly to the east during Friday night over the Plains.
Severe weather threat to shift to lower Plains on Saturday
As a push of drier and cooler air shifts eastward Saturday, so will the threat of severe weather.
The threat for severe thunderstorms is forecast to extend from central and northeastern Texas to perhaps as far north as Iowa during Saturday.
Damaging winds, flash flooding and isolated tornadoes are likely to be the main threats on Saturday.
The threat during Saturday afternoon and evening includes a number of major cities, such as Dallas; Oklahoma City; Wichita and Topeka, Kansas; Kansas City, Missouri; Omaha, Nebraska; and Des Moines, Iowa.
Storms to reach Mississippi River, perhaps Gulf coast on Sunday
On Sunday, the main threat of severe weather, including isolated tornadoes, will stretch from the central Great Lakes to the middle part of the Mississippi Valley.
While the concentration of severe storms may be in the northern part of this zone, the potential for at least isolated severe weather may exist as far south as Louisiana. Heavy, slow-moving storms across the lower Mississippi Valley may re-aggravate flooding concerns.
All forms of severe weather, including isolated tornadoes, are possible on Sunday.
New round of severe weather to begin on Monday
As another storm emerges from the Rockies, a new round of severe weather is likely to be sparked over the central and southern High Plains during late Monday and Monday night.
During Tuesday, the severe thunderstorm risk should once again advance eastward across the central and southern Plains and may reach from central Texas to northern Iowa and southeastern Nebraska.
Similar to the round of severe weather into this weekend, the next round has the potential to produce tornadoes. However, the exact timing, nature and coverage of the storms may not be known until later this weekend.
As is often the case during late May, and especially during amplified weather patterns, more rounds of severe weather are expected to follow beyond early next week.
The repeating rounds of thunderstorms and the heavy rain they contain are likely to elevate the risk of urban and small stream flooding, as well as send a new surge of water into area rivers and major waterways.
