The area was under a severe thunderstorm warning. A potent spring storm system that's expected to persist through the weekend raked across the Plains and Midwest Friday, spawning at least one tornado in Arkansas as blizzard conditions blanked much of the Northern... A potent spring storm system that's expected to persist through the weekend raked across the Plains and Midwest Friday, spawning at least one tornado in Arkansas as blizzard conditions blanked much of the Northern Plains.