Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 231 AM EST Sat Dec 10 2016 Valid 12Z Sat Dec 10 2016 - 12Z Mon Dec 12 2016 ...Pacific frontal system expected to bring heavy snow to portions of the Rockies and Intermountain West... ...Lake effect snows expected to gradually lessen in intensity today... ...Developing low pressure system across the plains to bring snow from the northern plains to the Northeast... An arctic frontal boundary remains draped from the northern Rockies into the interior Northwest. A Pacific frontal system and upper-level disturbance will spread moisture inland today where it will interact with the arctic front to produce snowfall. Snow is expected to be widespread at the higher elevations of the Intermountain West and central/northern Rockies, where heavy snow is possible. Farther west snow is expected to continue across the Cascades through the weekend, with rain at the lower elevations closer to the coast,the result of persistent onshore flow. Lake effect snow is expected to continue into today downwind of the Great Lakes, but should begin to gradually lessen in intensity through the day. Farther west, a low pressure system will begin to take shape across the central U.S. as upper-level energy crosses the Rockies and interacts with a lingering frontal boundary. Snow is expected to develop today from the northern plains to the upper Great Lakes, spreading east into the lower Great Lakes and the Northeast on Sunday. Farther south rain is expected on Sunday from the Ohio valley to the lower Mississippi valley, spreading into the southern/central Appalachians by early Monday. A few thunderstorms will be possible along the Gulf Coast. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php