Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 334 PM EDT Fri Nov 03 2017 Valid 00Z Sat Nov 04 2017 - 00Z Mon Nov 06 2017 ...Heavy snow possible across portions of the Northern Rockies... ...Heavy rainfall and severe weather possible by Sunday afternoon from the Ohio Valley to the lower Great Lakes... ...Temperatures across the Southern and Eastern U.S. will be unseasonably warm through the weekend... A frontal boundary sinking slowly southward across the Western U.S. this evening will continue to allow for heavy snowfall across portions of the Northern Rockies tonight and into Saturday. Accumulations of 1 to 2 feet are possible for the highest terrain of northwestern Wyoming and southwestern Montana, where winter storm warnings are currently in effect. Light to moderate snows are also possible to the south across the Sierras, Intermountain West, and central Rockies, as well as further east across the northern Plains into the Upper Mississippi Valley. Snowfall across the West will wane slightly Saturday afternoon, but is expected to pick up again by Saturday evening into Sunday as another system moves inland off the Pacific. Expect moderate to heavy snowfall, with accumulations of 6 to 12 inches, across much of the Cascades range of Washington and Oregon. By the end of the weekend, low pressure will lift northward through the Upper Midwest as a cold front pushes eastward into the Ohio Valley. Expect widespread showers and thunderstorms to develop ahead of the boundary from the middle Mississippi Valley to the lower Great Lakes by Sunday. Significant moisture and instability will bring the threat for heavy rainfall, flash flooding, and severe thunderstorms, particularly during the peak heating hours of Sunday afternoon and evening. WPC is highlighting a marginal to slight risk for excessive rainfall/flash flooding, while SPC is highlighting a slight to enhanced risk for severe weather across these areas. Elsewhere, a lingering weak frontal boundary will keep scattered showers in the forecast from the lower Mississippi Valley to the Mid-Atlantic Friday into Saturday. Despite this, temperatures across the southern and eastern states will be unseasonably warm, with afternoon highs as much as 10 to 20 degrees above normal through the weekend from the southern Plains to the Ohio Valley. Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php