A deep upper low will bring heavy mountain snow and windy conditionsacross a large portion of the western U.S. through the next couple ofdays......A slight chance of severe thunderstorms across Texas and upper Midwestinto Sunday will shift into the central Plains by later on Monday......Critical fire danger is forecast for the southern Rockies...A rather vigorous and deep upper-level low currently approaching the WestCoast will result in the next wave of active and stormy weather to quicklysweep through the western U.S. and into the Great Plains during the nextcouple of days.  Moderate to heavy rain and high-elevation heavy wet snoware already reaching into the West Coast in earnest, especially acrosscentral to northern California.  The precipitation will expand quicklyinland across the Great Basin and a good portion of the Pacific Northwestthrough tonight, reaching into the northern Rockies on Sunday, followed bythe central Rockies on Monday.  This system will bring quite a bit ofwind, especially across southern California and Nevada through tonight,from the Four Corners region to Wyoming on Sunday before overspreadingmuch of the High Plains on Monday.  Two feet or more of heavy wet snow isexpected to accumulate along the Cascades in Oregon, with a foot along theSierra Nevada, and a foot or more for portions of the northern Cascades,Great Basin, as well as northern and central Rockies through Monday.  Inaddition, severe thunderstorms are expected to develop over the centralPlains later on Monday ahead of a potent cold front.  Meanwhile, thecenter of an elongated deep low pressure system is forecast to trackacross the northern Plains with wind-swept rain impacting the northernHigh Plains on Monday.