An intensifying Spring storm system emerging from the Rockies will heighten the threat of severe thunderstorms across portions of the Plains, with the primary threat shifting into the Midwest on Tuesday.  Early-week snow will blanket the northern and central Rockies, while storm-total rainfall could reach 1 to 3 inches across portions of the Plains and much of the Midwest.  During the second half of the week, the initial system will weaken, but a trailing disturbance should produce additional rain in parts of the central and eastern U.S.  

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