Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 317 AM EST Sun Nov 15 2015 Valid 12Z Sun Nov 15 2015 - 12Z Tue Nov 17 2015 ...Heavy snow possible across portions of the western U.S... ...Severe thunderstorms possible on Monday across the southern plains... ...Unsettled weather to continue for the Pacific Northwest... An amplifying upper-level trough will move into the western U.S. today as a surface cold front pushes inland. This powerful storm system will rapidly move across the western U.S. today and tonight, before moving into the plains on Monday. The storm system will bring snow to the Cascades and the Sierras this morning, before spreading snow into the Intermountain West tonight. Rain may initially fall in some of the valleys in the Intermountain West, but this should quickly transition to snow for most areas tonight as the upper-level trough brings colder air into the region. Heavy snow is possible today across the Cascades and the Sierras, with the highest elevations exceeding a foot of snowfall. The potential for heavy snow will shift into the Wasatch and the Colorado Rockies on Monday. Showers and thunderstorms are expected across the southern and central plains today and tonight as southerly flow increases moisture across the region. The system crossing the West today will begin to move into the central U.S. on Monday. A surface low is forecast to develop across eastern Colorado Monday afternoon and rapidly deepen. As southerly flow ahead of this system becomes quite strong, moisture and instability will rapidly increase. The strong and dynamic nature of this storm system combined with increasing instability will allow for numerous showers and thunderstorms across the southern and central plains on Monday. Severe thunderstorms are possible across portions of the southern plains -- and the Storm Prediction Center has outlined a slight to enhanced risk of severe thunderstorms for this area on Monday. Showers and thunderstorms will continue into Monday night as the storm system spreads east into the Mississippi River valley. The Pacific Northwest will see little break to dry out -- as another Pacific storm system will approach the area on Monday. This will bring another round of rain and mountain snows to the Northwest that will persist into Tuesday. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php