Severe thunderstorm and flash flooding threat exists across parts ofthe central/southern Plains tonight before expanding into the MississippiValley on Thursday...Critical Fire Weather potential over portions of the Southern HighPlains through this evening.Cool and snowy in parts of the Northwest with above average andpotentially record breaking temperatures into the Ohio Valley andMid-Atlantic on ThursdayA very active start to May is underway throughout much of the central andsouthern Plains ...