Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EST Sun Feb 16 2020 Valid 12Z Sun Feb 16 2020 - 12Z Tue Feb 18 2020 ...Heavy snow expected for the higher elevations of the Cascades to the Northern and Central Rockies... ...Heavy snow for the Upper Great Lakes... ...Temperatures will be 10 to 15 degrees below average... Upper-level troughing and cold air flowing over the Great Lakes will aid in producing lake effect snow down wind from the Great Lakes that will continue through late Sunday night. While moisture from the Western Gulf of Mexico will stream over the Central Gulf Coast along with favorable upper-level jet dynamics will aid in producing rain showers over parts of the Central Gulf Coast that will expand eastward into the Southeasts on Sunday into Sunday evening. Some rain will also develop over parts of the Central Appalachians on Sunday afternoon into Sunday evening. The rain will move off the Southeast Coast by Monday afternoon. Meanwhile, onshore flow off the Pacific and upper-level energy will aid in producing coastal rain and higher elevation snow over the Pacific Northwest with snow developing over the Northern Intermountain Region and Northern Rockies that will start to taper off overnight Monday. Developing storm over the Northern High Plains will move eastward into the Upper Great Lakes by Tuesday. The system will aid in producing snow over the Upper Mississippi Valley on Monday afternoon. A sustained onshore flow from the eastern Pacific will continue to push waves of moisture across the Pacific Northwest into the Intermountain region toward the northern Rockies. This will continue to bring heavy wet snow across the higher elevations such as the Cascades, the Bitterroot mountains and the Tetons. Meanwhile, over an inch of rain can be expected for the lower elevations in these areas through the weekend before the precipitation showing signs of letting up on Monday. Meanwhile, cold temperatures over the eastern U.S. will moderate on Sunday as the cold high pressure system slides east of New England. This will keep way to southerly flow to return across the Plains and allow moisture from the Gulf of Mexico to stream northward back into the Deep South. The chance of showers and thunderstorms are expected to increase from west to east along the Gulf Coast as a front forms just offshore. By Monday, the rain and thunderstorms should expand farther inland when the moisture interacts with a couple of frontal systems arriving from the northern and central Plains. Cold air will remain in place across the northern Plains into the Great Lakes through the weekend and will begin to push southward into the central Plains on Monday. This will increase the chance of snow and mixed precipitation across the upper Midwest and into the Great Lakes on Monday when a low pressure wave develops along the associated cold front. Another cold front moving across the western U.S. will keep a good chance of snow for much of Colorado on Monday along with an increasing chance of rain for the Mid-Mississippi Valley where another low pressure wave is forecast to form. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php