An active, variable spring weather is expected during this period as the wave pattern of the flow amplifies, deamplifies, shifts position, and reamplifies. Starting with a rather flat flow, by Friday May 4 most models forecast a fairly deep cutoff upper level low to form over the intermountain West. Some moist Gulf inflow coupled with strong easterly flow at low levels is expected to produced heavy rainfall over central and southern portions of the eastern slopes of the Rockies and over the central and parts of the southern Plains.
Heavy snow is possible at the higher elevations of the central Rockies.
After that the upper level system is forecast by the MRF model to move east and bring cool, wet weather to much of the eastern half of the nation while a ridge is forecast to build along the West Coast, bringing at least a temporary end to the recent beneficial precipitation there. Heavy rains over the Great Plains and parts of the middle Mississippi Vally may produce local flooding and may ultimately add to the Mississippi River crest downstream from the Missouri River confluence. Heavy snow is possible at the higher elevations of the central Rockies. Unseasonable rains will bring some drought relief to the Florida peninsula, with a chance of significant relief elsewhere across the Southeast. Areas of the Northwest with low mountain snowpack are unlikely to experience much additional relief during the next two weeks.