Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 305 PM EST Thu Dec 10 2020 Valid 00Z Fri Dec 11 2020 - 00Z Sun Dec 13 2020 ...Low pressure to bring winter weather from the Rockies to Upper Great Lakes Friday into Saturday... ...Rain and snow for the Northwest... ...Temperatures will be 10 to 20 degrees above average over the eastern third of the country, while parts of the Central/Southern Rockies and the Central and Southern High Plains will be 10 to 15 degrees below average... A developing storm over the Southern/Central Rockies will move northeastward to the Great Lakes by Saturday evening. The system will produce rain and higher elevation snow over the Southwest into the Central/Southern Rockies overnight Thursday. On Friday, the snow over the Central/Southern Rockies will expand onto the Central Plains while showers and thunderstorms develop over the Southern Plains. On Friday evening, rain and snow will develop over parts of the Upper/Middle Mississippi Valley and will start to wind down on Saturday evening. As the storm moves into the Ohio Valley/Great Lakes on Saturday, rain with embedded thunderstorms will develop over the Ohio Valley, and rain will extend from the Southern Ohio Valley to the Central Gulf Coast. On Saturday, moderate to heavy snow will develop over parts of the Great Lakes and rain/snow will also develop over parts of the Northeast by Saturday evening. The snow will help in creating hazardous driving conditions over the region. Ahead of the storm, southerly breezes will allow temperatures to become 10 to 20 degrees above average over the country's eastern third. In comparison, parts of the Central/Southern Rockies and the Central and Southern High Plains will be 10 to 15 degrees below average. Energy and moisture will move into the Northwest on Thursday evening and will aid in producing rain and higher elevation snow over the Pacific Northwest. Snow will move into the Northern Intermountain Region on Friday and the Northern Rockies on Saturday. Rain and higher elevation snow will move into parts of Northern California while snow develops over parts of the Great Basin on Saturday. The snow will contribute to dangerous driving conditions over the area. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php