A life-threatening situation will continue into tonight from Upper Midwest to the Mississippi River Valley as tornadic-thunderstorms continue to organize.
Madison, Wis., and Cedar Rapids, Iowa lie in the heart of the tornado threat area that extends from central Wisconsin to central Iowa.
The potential for additional tornadoes exists into tonight as powerful winds aloft and daytime heating help fuel severe thunderstorms. Storms that produced multiple tornadoes on Saturday will re-ignite over the next few hours.
Some of the tornadoes could be very strong and remain on the ground for miles.
Dangerous Setup for Storms
AccuWeather.com Meteorologist Meghan Evans first warned of the threat for tornadoes earlier in the week, saying, "The ingredients for a tornado outbreak may come together across portions of the Plains later Saturday and Sunday"
A powerful storm that slammed into the West earlier this week is ejecting northeastward through the Plains.
The storm system, combined with a strong rush of wind aloft via the jet stream and a warm, moisture-rich air mass in place originating from the Gulf of Mexico will spark powerful thunderstorms capable of producing tornadoes into tonight.
The difference in wind direction well up in the atmosphere (from the west) and at the surface (from the south) will enhance the threat for tornadoes.
The thunderstorms that will spawn the tornadoes will also drop large, damaging hail to the size of softballs, and could produce powerful wind gusts in excess of 60 mph without the help of a funnel.
Numerous tornadoes were spawned across the Plains Saturday afternoon and overnight, but as the storm system tracks eastward, more thunderstorms capable of producing damaging tornadoes will fire late this afternoon and this evening.
The greatest risk for tornadoes will be across southern Wisconsin, eastern Iowa and western Illinois through this evening, though any location in the Upper Midwest will have the potential for tornadoes.
Portions of several major highways will be at risk, including Interstates 30, 35, 39, 40, 44, 55, 70, 72, 74, 80, 88, 94, and 380.
If you are traveling and a potential tornado is approaching, be prepared to abandon your vehicle and seek safe shelter. Better yet, stay off the roads if you hear that thunderstorms are approaching.
Because of the threat, it is imperative that you keep up to date with the weather situation over the next several days, especially into tonight. Have a plan of action before the storms develop.
Immediately head to the basement or a storm shelter if a warning is issued. Mobile homes and trailers should always be evacuated, as well.
Knowing ahead of time what to do in the event of a tornado or strong thunderstorm could save your life.
We value your tornado pics, but we value your life more. Please take shelter during dangerous situations this weekend.
Story updated by Andy Mussoline, Meteorologist
Several disturbances pose the threat to become the first named tropical system in the Eastern Pacific Ocean over the next week.
Lifeguards along the East and Gulf coasts are preparing to deal with one of the greatest beach dangers: rip currents.
A dangerous and life-threatening flooding situation will continue into Memorial Day, across portions of Texas, Oklahoma, Kansas, Arkansas and Missouri.
Showers and thunderstorms threaten to interfere with Memorial Day festivities across more than half of the United States.
Many areas in the Eastern states will have consistent summerlike heat and a buildup of humidity for the last week of May.
Severe thunderstorms will rumble across the southern Plains on Monday, impacting similar areas that were hit earlier in the holiday weekend.
Philadelphia, PA (1991)
96 degrees -- a record sixth 90-degree reading for the month. (The month ended with twelve 90-degree days.)
Chicago, IL (1992)
32 degrees, latest 32 or lower on record.
Iowa City, IA (1859)
Waterspout; 8 killed, one child was taken up, carried 500 yards and thrown in a slough but survived.