Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 249 AM EST Thu Feb 11 2016 Valid 12Z Thu Feb 11 2016 - 12Z Sat Feb 13 2016 ...Heavy lake effect snow possible downwind of Lakes Erie and Ontario... ...Arctic air mass expected to spread into much of the eastern U.S. by Saturday... ...Heavy rain and snow possible in the Pacific Northwest... A series of cold air surges headed across the Great Lakes through the next few days will result in lake effect snows int he favored areas downwind of the Great Lakes. Through Saturday morning, some areas downwind of Lakes Erie and Ontario may receive up to a foot of additional snowfall. Snowfall amounts of 5 to 10 inches are possible for the same time period across portions of Michigan downwind of Lakes Superior and Michigan. On Friday, an Arctic cold front will move into the Great Lakes, and will reach the Mid-Atlantic and Northeast by Friday night/Saturday morning. This front will usher in a frigid air mass in its wake. Temperatures on Friday will be 20 to 30 degrees below average across portions of the Upper Midwest. By Saturday, this cold air mass will overspread much of the central/eastern U.S., with high temperatures 20 to 30 degrees below average for much of the Great Lakes, Midwest, Ohio and Tennessee valleys, Mid-Atlantic, and the Northeast. An upper-level disturbance and a lingering stationary frontal boundary will bring light precipitation to the northern plains today. A mixture of rain and snow are possible, with sleet or freezing rain for some areas. A frontal system will move into the Pacific Northwest today, with precipitation spreading across the region in advance of the front. Locally heavy rain will be possible over the Olympics and the Washington Cascades today -- with snow falling at the highest elevations. Snow levels will decrease on Friday as the frontal system moves inland, with more of the Cascades and the Olympics experiencing snowfall as onshore flow lingers in the wake of the front. This system will also spread rain and snow into the northern Intermountain West Friday into Saturday as it moves inland. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php