The severe weather threat shifts into the Mississippi Valley, while snowdevelops over the Northwest on Tuesday. Scattered showers andthunderstorms are expected to propagate into the Upper/Middle MississippiValley Tuesday morning and then over the Lower Mississippi Valley Tuesdayafternoon. SPC has another Enhanced Risk of Severe Thunderstorms out overparts of southeast Iowa, northern Missouri and west-central Illinois witha broader Slight Risk (level 2/5) area extending from northern Iowa down...