Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 224 AM EST Fri Dec 11 2020 Valid 12Z Fri Dec 11 2020 - 12Z Sun Dec 13 2020 ...A swath of light to moderate snow is likely from the central Rockies to the upper Great Lakes through early this weekend; impacting northern Maine by Sunday morning... ...Multiple rounds of rain and snow for the Pacific Northwest and northern California... ...Additional winter weather possible across the central/southern Rockies by late Saturday and stretching into the southern Plains by Sunday... A developing storm over the southern Plains and Midwest will gradually strengthen and move northeast toward the Great Lakes by Saturday. This system will produce higher elevation snow over the central/southern Rockies today, while also fueling showers and thunderstorms across the Arklatex region and Lower Mississippi Valley. The snow over the central/southern Rockies will expand into the central Plains today. By this evening, rain and snow will develop over parts of the Upper/Middle Mississippi Valley. As the storm moves into the Ohio Valley/Great Lakes on Saturday, moderate to heavy snow will develop over parts of the Great Lakes with rain/snow also pushing into parts of New England by Saturday evening. Total snowfall amounts around 3 to 6 inches are forecast from southeast Nebraska to southern Wisconsin, with locally higher amounts possible. The highest snowfall is likely to occur across northern Michigan, where 6 to 12 inches of snow could accumulate. This amount of snow will likely lead to treacherous travel across the region. Ahead of the storm, widespread southerly winds will allow temperatures to become 10 to 20 degrees above average over the country's eastern third. In comparison, parts of the central and southern High Plains will be 10 to 15 degrees below average. Lingering high elevation snow will be found across the Pacific Northwest and Intermountain West today as two energetic storm systems approaches the West Coast. The first system is an area of low pressure that is forecast to swing across the region this evening followed by a strong cold front on Sunday. The biggest impact along the West Coast will be potentially heavy rain along coastal regions of northern California and Oregon. Total rainfall amounts up to 4 inches are possible and could lead to isolated flooding. Upwards of two feet of snow could fall across the Sierra and Cascade mountain ranges as well. The aforementioned area of low pressure to impact the West Coast this evening is expected to move into the southern Rockies by Saturday evening and into the southern Plains by Sunday. Light to moderate snow will be found to the north of the low across the central/southern Rockies and southern Plains. There remains some uncertainty will exact snowfall amounts, but impactful winter weather will be possible from Colorado to central Oklahoma to end the weekend. Snell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php