Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 257 AM EST Mon Dec 04 2017 Valid 12Z Mon Dec 04 2017 - 12Z Wed Dec 06 2017 ...Heavy snow possible over the Upper Mississippi Valley and parts of the Upper Great Lakes.. ...Heavy rain possible over parts of Upper Peninsula of Michigan... ...Heavy rain possible over parts of the Southern Appalachians/Tennessee Valley... ...Temperatures will be 20 to 30 degrees above average over parts of the Middle/Upper Mississippi Valley... A strong storm over the Middle Missouri Valley will advance northeastward into Central Ontario by Tuesday evening. The system will produce snow over parts of the Northern/Central Rockies ending by Monday evening. Snow will also develop over the Northern Plains expanding into parts of the Upper Mississippi Valley by Monday evening with the snow becoming heavy. The heavy snow will expand into parts of the Upper Great Lakes overnight Monday with the heavy snow moving into Southwestern Ontario on Tuesday into Tuesday afternoon. Light snow will continue over parts of the Upper Great Lakes Tuesday afternoon into Tuesday evening. In addition, showers and thunderstorms will develop over parts of the Upper/Middle Mississippi Valley into parts of the Upper Great Lakes on Monday morning. Showers and thunderstorms will also expand southward along the associated front over the Middle Mississippi Valley into parts of the Southern Plains by Monday evening. On Tuesday, showers and thunderstorms will move into the Lower Mississippi Valley that will become confined to the Central Gulf Coast by Tuesday evening. Additionally, rain that will be heavy at times will move into the Upper Great Lakes late Monday morning into Monday evening. Overnight Monday, the rain will move eastward into the Lower Great Lakes to parts of the Lower Mississippi Valley/Southern Plains. On Tuesday, rain will develop over parts of the Mid-Atlantic/Northeast as the rain along the front moves eastward to the Northeast roughly southwestward to the Central/Southern Appalachians into the Lower Mississippi Valley by Tuesday evening. Meanwhile, a secondary front will move southward out of West-Central Canada moving into the Middle Mississippi Valley by Tuesday evening. Light snow will develop over parts of the Northern High Plains overnight Monday moving into parts of the Northern Plains by Tuesday evening. Elsewhere, moisture from the Western Gulf of Mexico will move northward over the Southern Plains as upper-level energy moves eastward over the Lower Mississippi Valley and dissipating over parts of the Southeast overnight Monday. The energy and moisture will aid in producing showers and thunderstorms over parts of the Western Gulf Coast/Southern Plains on Monday that will expand into parts of the Lower Mississippi Valley overnight Monday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php