Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 140 AM EST Sat Dec 19 2015 Valid 12Z Sat Dec 19 2015 - 12Z Mon Dec 21 2015 ...Cold this weekend for the Eastern U.S. followed by a warm-up by Monday... ...Active storm pattern for the West to continue with coastal rain and mountain snow... Cold weather has returned to the eastern U.S. after a rather prolonged stretch of above normal temperatures. In addition, there will be enough cold air surging across the Great Lakes to generate areas of lake effect snow through Saturday afternoon, with the heaviest snow expected downwind of Lake Erie and Lake Ontario. The cold snap should be short-lived with milder air returning by the beginning of the week as the winds turn more southerly and the surface high moves offshore. A series of storm systems will continue to move eastward across the eastern Pacific and move across the Pacific Northwest. A cold front will continue moving south and east with significant rain from central California northward to the Washington and Oregon coasts through Saturday. The heaviest snow is expected over the Sierra Nevada and the Cascades, where amounts in excess of one foot are likely at the highest elevations. The system will weaken and generate mountain snow on Sunday as it crosses the Great Basin and Central Rockies. By Sunday afternoon, a new surface low is forecast to develop over the southern Plains and track toward the Great Lakes by Monday morning. This system will advect moisture northward from the Gulf of Mexico, and showers will develop ahead of a cold front moving across the Mississippi Valley to the Great Lakes. The next storm system hammers the Northwest coast on Sunday morning with coastal rain and mountain snow before moving inland and weakening Sunday night. Strong and gusty winds are likely ahead of the trailing cold front, especially near the coast. Round three is expected to arrive by Monday afternoon with yet another round of precipitation. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php