WALDRON â€” Forecasters warned that large hail and more tornadoes could strafe parts of Oklahoma, Arkansas and Missouri on Friday, a day after powerful storms and floods killed at least three people in the storm-weary region.
Up to a dozen tornadoes touched down in mostly rural parts of Arkansas on Thursday, as well as one in Illinois and three in Oklahoma.
The National Weather Service was sending teams to survey the aftermath of Thursday's storms in Arkansas. Warning coordination meteorologist in Little Rock, John Robinson, said it could take days for the weather service to confirm whether tornadoes struck as flooded highways was hindering access to the storm-hit areas.
The agency's Storm Prediction Center in Norman, Okla., said large hail and tornadoes are likely Friday in Oklahoma and parts of the Ozarks in Arkansas and Missouri. The areas at greatest risk include Oklahoma City, Tulsa and Joplin, Mo., where the second-deadliest American tornado on record killed at least 158 people in 2011.
Thursday's tornadoes all appeared to be much less dangerous than the top-of-the-scale EF5 storm that struck Moore, Okla., on May 20 and killed 24 along its 17-mile path. The U.S. averages more than 1,200 tornadoes a year, but EF5 storms like the one in Moore â€” with winds over 200 mph â€” happen only about once per year. The tornado last week was the nation's first EF5 since 2011.
This spring's tornado season got a late start, with unusually cool weather keeping funnel clouds at bay until mid-May. The season usually starts in March and then ramps up for the next couple of months.
Of the 60 EF5 tornadoes since 1950, Oklahoma and Alabama have been struck the most, seven times each. More than half of these top-of-the-scale twisters have occurred in just five states: Alabama, Iowa, Kansas, Oklahoma and Texas.