Heavy snow likely across northern New York northern New England onSaturday.A wet weekend ahead for the East and West Coasts.A significant winter storm is in store for the northern Plains bySaturday night into Sunday morning.Quite an active weather pattern is quickly emerging across the country aswe head into the weekend.  A high pressure system from Canada will set thestage for sustaining the cold air that is already in place across thenorthern tier states.  Meanwhile, a trough of low pressure currentlysliding eastward into the western Gulf Coast region at the upper levelswill be instrumental in developing a low pressure system that willgradually intensify and track up the East Coast during the weekend.  Inthe near term however, the upper trough will mutually interact with amesoscale front and plenty of warm/moist air in the Gulf of Mexico tobring a round of heavy rain mainly across southern Florida throughtonight.  The heavy downpours are expected to be accompanied with strongto severe thunderstorms and possibly squalls as the core of the systempasses through.  By Saturday, the heavy rain will likely taper off toscattered showers behind a cold front across Florida.  Meanwhile, theheavy rain is expected to overspread much of the Eastern Seaboard onSaturday where widespread 1-3 inches of rainfall will likely result inflooding concerns along the I-95 corridor as a low pressure wave isforecast to track up the East Coast along a sharp coastal front.Farther north, the low pressure system will interact with the cold airmass in place across the northern tier states to bring a round of heavysnow from northern New York across northern New England on Saturday whereone foot to locally 20 inches of new snow is anticipated.  It appears thatthere will be a narrow zone of transition across central New England tocoastal Maine where heavy freezing rain and sleet can be expected Saturdaynight as the low pressure wave approaches.  The precipitation will thenrapidly change over to snow before ending early Sunday morning as thesystem exits into the Canadian Maritimes.Meanwhile, another upper trough and surface low pressure system from theeastern Pacific are heading toward the West Coast.  This system will bringwidespread mountain snow and lower-elevation rain into the PacificNorthwest and California on Saturday where a couple inches of rain ispossible near the coast, and up to a couple of feet of heavy snow for theSierra Nevada.  The system will reach into the Great Basin, theIntermountain region and into the northern Rockies Saturday night.  FromSaturday night into early Sunday, a low pressure system is forecast todevelop and intensify over the central High Plains.  This system will theninteract with the cold air mass already in place across the northern tierstates to deliver a significant winter storm across the northern Plains bySunday morning.