Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 355 PM EST Fri Dec 11 2015 Valid 00Z Sat Dec 12 2015 - 00Z Mon Dec 14 2015 ...Heavy rain possible over the Pacific Northwest to Northern California... ...Heavy rain over parts of the Southern Plains/Lower Mississippi Valley... ...Heavy snow for the Cascades and parts of the Northern Intermountain Region... A low pressure system and associated cold front will spin up over the Southern Plains once it crosses the Central/Southern Rockies- while a quasi-stationary front develops from the Central Plains to Southern New England by Saturday evening. Light rain is expected for the Upper Midwest to the Great Lakes region. Ample moisture from the Gulf of Mexico will stream in ahead of this system, which will aid in the development of scattered to widespread showers and thunderstorms from the Southern Plains to Middle Mississippi Valley Friday and Saturday as the cold front treks to the east. A slight risk of severe thunderstorms is possible for Saturday for portions of Texas, Oklahoma and Kansas. This same area will have an increased threat of excessive rainfall that could lead to areas of flash flooding. Snow, and or mixed precipitation, is forecast for portions of the Northern and Central Plains in the wake of this system as cold air surges in. By late Saturday, the central pressure will deepen over the Central Plains (near Iowa)and the cold front will surge through the Lower/Middle Mississippi Valley. The warm front will lift into the Midwest/Upper Midwest Sunday and into Monday. Widespread rain is expected from Louisiana north to Wisconsin/Upper Michigan. Precipitation will likely be mixed or all snow from western Oklahoma to northern Minnesota. Upper-level energy and onshore flow persist in producing rain along the West Coast through Saturday morning - with snow over the higher elevations over the West Coast over the Northern Intermountain Region/Northern Rockies into the Central Rockies. Precipitation intensity will briefly taper off Saturday afternoon. A new front will approach the Pacific Northwest late Saturday night bringing more rain and higher elevation snow through Monday. Portions of the Cascades and Northern/Central Rockies will likely have long periods of heavy snow. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php