Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 259 PM EST Sat Jan 20 2018 Valid 00Z Sun Jan 21 2018 - 00Z Tue Jan 23 2018 ...Heavy snow possible from parts of the Central Plains to the Upper Mississippi Valley... ...Rain/freezing rain possible over parts of the Central Plains to the Great Lakes... ...Heavy snow possible over the Cascades... ...Heavy rain possible over parts of the Pacific Northwest and Northern California... A storm over the Central Rockies will move eastward to the Middle Mississippi Valley by Monday. The system will produce snow and lower elevation rain over parts of the Northern/Central Rockies and parts of the Great Basin/Southwest that will expand eastward into the Southern Rockies and parts of the Northern/Central Plains by Sunday morning. On Sunday, the snow will end over parts of the Northern Rockies and the Great Basin/Southwest. Overnight Sunday into Monday, the snow will move into parts of the Upper Mississippi Valley/Upper Great Lakes. Also overnight Sunday into Monday, snow may be heavy at times over parts of the Central Plains into the Upper Mississippi Valley. In addition on Sunday, along the transition from rain to snow over the Central Plains/Middle Mississippi Valley a band of rain/freezing rain will develop. The rain/freezing rain area will expand into parts of the Upper Mississippi Valley/Great Lakes overnight Sunday into Monday, too. Moisture from the Western Gulf of Mexico will flow northward over parts of the Lower Mississippi Valley into the Tennessee Valley overnight Saturday into Sunday. On Sunday, a more intense moisture plume will move northward over the Southern Plains into the Lower/Middle Mississippi Valley afternoon Sunday into late Sunday night. By Monday morning, the plume of moisture will extend from the Eastern Gulf Coast northward to the Western Ohio Valley. The moisture will aid in producing light rain over parts of the Lower Mississippi Valley/Western Gulf Coast, Saturday evening, that will expand northward over the Middle Mississippi Valley/Ohio Valley by Sunday morning. On Sunday afternoon, showers and thunderstorms will develop over parts of the Southern Plains that will expand northeastward into the Lower/Middle Mississippi Valley by Sunday evening. By Monday morning, the showers and thunderstorms will be confined to Lower Mississippi Valley/Tennessee Valley. Rain will also develop over Middle Mississippi Valley into Ohio Valley with some light rain developing over parts of the Northern Mid-Atlantic overnight Sunday into Monday. More to Follow Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php