Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 247 PM EST Mon Dec 12 2016 Valid 00Z Tue Dec 13 2016 - 00Z Thu Dec 15 2016 ...Wintry weather possible for portions of the lower Great Lakes, Mid-Atlantic, and Northeast... ...Heavy snow possible across portions of the Intermountain West and northern Rockies... ...Stream of Pacific moisture to bring heavy rain and snow to portions of the West Coast Tuesday and Wednesday... Wintry precipitation is impacting the Great Lakes, Northeast and Mid-Atlantic regions this afternoon as a deepening low-pressure pressure system lifts north and east. A mix of snow, sleet, and freezing rain is possible; while heavy snow will impact portions of northern Michigan and areas downwind of the Lakes in Pennsylvania and New York. Rain is expected for the the southern Mid-Atlantic region to the Southeast and Tennessee valley. The trailing end of the associated cold front will stall along the Gulf Coast, and will begin moving northward again as a warm front on Tuesday, keeping rain and a few thunderstorms a possibility from the Gulf Coast to the Southeast into Wednesday. A low pressure system will track toward the West Coast tonight through Tuesday and pushing inland on Wednesday. A stream of very moist air will interact with this system; spreading substantial precipitation into central and northern California. Heavy rain will be possible, with heavy snow at the higher elevations in the Sierras. Heavy rain and snow will persist across the West Coast through midweek. Another surge of arctic air will enter the northern Plains and Midwest; resulting in forecast highs ranging 20 to 30 degrees below average across portions of the northern plains. These cold temperatures will spread east into the Midwest for Tuesday and Wednesday. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php