* WHAT...Heavy snow possible. Accumulation amounts are uncertain at this time, but may range from around a foot at 3000 to 4000 feet and 4 to 8 feet at higher elevations. Winds could gust as high as 55 mph. * WHERE...West Slope Northern Sierra Nevada and Western Plumas County/Lassen Park including Interstate 80 and Highway 50, northern Shasta County including portions of Interstate 5, the Coastal Range, and foothill regions of the Sierra Nevada. * WHEN...From Sunday evening through Wednesday evening. * IMPACTS...Dangerous to near impossible travel conditions with chain controls and road closures possible. Low visibility due to a combination of wind and heavy snow. * ADDITIONAL DETAILS...Snow levels will be around 4500-5000 feet Sunday night through Tuesday. Levels drop to 3000 to 4000 feet late Tuesday into Wednesday. Potential to see snow levels as low as 2000 feet for areas along the Coastal Range, around Shasta County, and in the southern Cascades.