A stormy pattern that has been on AccuWeather meteorologists' watchful eye since mid-March will evolve into a heavy rain event with severe thunderstorm activity over the south-central United States from Monday to Thursday. Enough rain could trigger flooding, and severe thunderstorms may erupt and spawn tornadoes. A jet stream pattern that has pinned stormy conditions to the Northeast and the West much of this week will break down over the next few days. The result will be a jet stream that can a