March 27 (UPI) -- Close to 30 million people may be at risk for severe thunderstorms over the central United States as a volatile weather pattern unfolds into Saturday, and AccuWeather meteorologists say some of the storms will be capable of spawning strong tornadoes.
The situation may become especially dangerous with as the severe weather outbreak reaches its peak during Saturday afternoon and evening, then the risk of strong tornadoes will be the highest.
The main severe weather threat will arise as a storm system, which will unleash snow in the Rockies, emerges from the region and tracks northeastward across the Plains and then the Upper Midwest.
The first strong storms in the pattern ramped up during Thursday night over portions of eastern Kansas to central Missouri and southwestern Illinois.
Areas south of Kansas City, Mo., and the suburbs of St. Louis had a noisy night when pounding rain, vivid lightning, loud thunder and hail tracked along the Interstate 70 corridor late Thursday into early Friday. Hail up to the size of golf balls fell over Tulsa and Rogers counties, Oklahoma, around 3:30 Friday.
Through Friday afternoon into the evening, hail continued to fall over northeastern Oklahoma into southern Missouri, with preliminary reports of hail up to 2.5 inches in diameter damaging cars in Delaware and Mayes counties, Okla.
The storm threat is forecast to expand over a more broad area of the Mississippi Valley from late Friday through Saturday evening.
In addition to the large hail and tornado threat, strong straight-line wind gusts with an AccuWeather Local StormMax of 70 mph can occur. Winds this strong can break large tree limbs and knock over poorly-rooted or diseased trees. Sporadic power outages are possible in addition to the risk of falling trees.
Flash flooding is another significant concern with the storms. Even though many of the storms will be fast-moving and last less than an hour, some areas, such as the Ohio Valley and central Plains, can experience repeating storms that bring excessive rainfall.
"From late Friday afternoon to Friday evening, severe storms are expected to erupt from northeastern Oklahoma, eastern Kansas, central Missouri and central Illinois," AccuWeather lead storm-warning meteorologist Brian Knopick said.
There is also the potential for thunderstorms to become severe at the local level over portions of Indiana and Ohio, as well as south-central Oklahoma and north-central Texas during Friday.
The severe weather risk will not only continue on Saturday but could pose a significant threat to lives and property.
During Saturday, the severe weather threat may extend as far to the north as central Iowa and southern Wisconsin and as far to the south as northeastern Texas and northwestern Louisiana. Large metro areas of Chicago, St. Louis, Davenport, Iowa, and Little Rock, Ark., are among the areas at risk.
"Storms from northern Missouri and southern Iowa to central Illinois may have the greatest potential for tornadoes on Saturday, but this threat area may lift northward later in the day and early in the evening," Knopick said.
The tornadoes that erupt in Missouri, Iowa and Illinois have the potential to be strong and fast-moving on Saturday. People in these areas will need to have a plan of action in place before the storms strike.
"Farther south along the cold front, a more common threat is likely to be damaging winds and hail during Saturday," Knopick stated.
As Saturday evening progresses, storms are forecast to advance across Indiana, the western parts of Kentucky and Tennessee, southeastern Arkansas and the northwestern parts of Mississippi and Louisiana. People in Indianapolis; Louisville, Ky.; Memphis, Tenn.; Tupelo, Miss.; and Shreveport, La.; may be at risk for rapidly changing severe weather conditions.
"Since a significant number of the storms, including a tornado risk, will exist for a time after dark Friday and Saturday, this outbreak could be especially dangerous," AccuWeather meteorologist Brandon Buckingham said.
From later Saturday night to Sunday, the setup for severe weather will likely become less defined and the storms are forecast to diminish in intensity. However, there can still be heavy, gusty and locally severe storms from southeastern Michigan, southern Ontario and central New York state to northern Georgia, central Alabama and central Mississippi.
The severe weather threat comes at a time when worry about and precautions for COVID-19 increase across the nation. Experts urge people to check whether their community shelters will be open amid coronavirus restrictions ahead of time, so alternate plans can be made as needed.
AccuWeather meteorologist Tom Bedard, a volunteer firefighter and EMT who regularly works with emergency management officials, said residents who own a tornado shelter should clean the shelter out immediately and make sure they are stocked with blankets, helmets and backpacks with some clothes, necessities and first aid equipment.
For those without a shelter, he recommended communicating with friends and neighbors for sheltering possibilities well before warnings are issued and heading to a safe place ahead of the storms.
If you can't make it to a shelter or a family or friend's residence, AccuWeather meteorologist and emergency preparedness specialist Becky DePodwin said residents should take cover in a bathroom with no exterior walls, a stairwell or a basement.
Temporary triage and testing centers have been set up outdoors in some communities amid the pandemic. These shelters could be at significant risk to these operations should severe weather roll in.
The strengthening storm from the Rockies will pull warm air that has been building over the Deep South since the start of this week northward due to the circulation around the system. At the same time, moisture will surge northward from the Gulf of Mexico, as a sweep of dry air pushes eastward from the southern High Plains.
A strong jet stream overhead will create what is known as strong wind shear, or changing wind speed or direction with altitude, over the lower Plains and Mississippi Valley. It is as these conditions come together that thunderstorms will erupt and become severe.
Not long after the severe weather risk diminishes during the latter part of the weekend, a new round of severe thunderstorms and flash flooding may arise early next week over the South Central states.