Thunderstorms are expected to develop this afternoon and continue through tonight as a warm front lifts north into the area. Some storms may be severe, with the main threat large hail to around 1 inch in diameter during the late afternoon and evening hours. There is a chance that a few supercells could develop along the warm front between 3 pm and 9 pm, bringing a threat for very large hail, damaging winds and tornadoes to areas of far southeast Iowa, west central Illinois and especially northeast Missouri. The threat overnight will shift to heavy rain and possibly localized flash flooding along and mainly north of I-80. One or more rounds of thunderstorms are expected again Tuesday and Tuesday night ahead of a cold front, with the threat of severe weather and heavy rainfall continuing.