Much colder conditions arrive behind cold front for the Eastern half ofthe nation.Impressive winter storm will hammer the Cascades to the Sierra withblizzard conditions to end the week.A reality check is in progress across the eastern half of the countryafter the record-breaking warmth that was observed on Tuesday across a bigportion of the Plains and Midwest states.  The strong cold front that isheralding this change to much colder conditions will be exiting the EastCoast Wednesday evening, with a corridor of showers and some thunderstormsextending from the coastal Southeast U.S. to New England, followed by anabrupt drop in temperatures and windy conditions overnight into earlyThursday.  Wind advisories and high wind warnings are currently in effectfor much of the Northeast and Mid-Atlantic region through early Thursday.March will be coming in like a lion for the West Coast states.  Anextremely potent winter storm will be making all kinds of weatherheadlines for the higher terrain of Washington, Oregon, and California,particularly for the Sierra going into Friday and Saturday.  A prolongedperiod of upslope flow, combined with abundant moisture from the Pacificand lowering snow levels, will result in a multi-day heavy snowfall eventwith blizzard conditions as winds gust well over 50 mph.  The potentialexists for snowfall totals on the order of 5-10 feet by Saturday eveningfor the higher elevations of the Sierra!  This will result in a travelnightmare for the mountain passes that are affected, and will likelyresult in numerous road closures.  There will also be moderate to heavysnow for the higher terrain of the Northern Rockies, but not to the samemagnitude as the Sierra and Cascades.  Heavy rain is expected for thecoastal areas between San Francisco and the Olympic Peninsula ofWashington where a few inches are likely over the next 3 days. Elsewhere across the continental U.S., moisture will be on the increasenorth of a surface low across the northern Gulf on Friday, and a swath ofmoderate to locally heavy rain is expected from southern Louisiana tonorthern Georgia, with some locations possibly getting over an inch ofrainfall.  Showers are also expected from southeast Arizona to westernTexas Wednesday night, and higher elevation snow showers, with the coldfront dropping south and an upper level shortwave passing through theregion.  Dry conditions are forecast for the central/northern Plains intothe Midwest states with high pressure governing the overall weatherpattern.