Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 250 AM EST Tue Nov 26 2024 Valid 12Z Tue Nov 26 2024 - 12Z Thu Nov 28 2024 ...Heavy snow over parts of the Sierra Nevada Mountains, Great Lakes and Central Rockies... ...Below average temperatures in the Plains... A moderate level atmospheric river event will accompany a surface low pressure system as it moves into the West today. This AR will spread anomalous moisture over southern/central California, the Great Basin and Central Rockies. Heavy coastal and mountain rain may lead to instances of flash flooding, particularly over the windward foothills of the southern Sierra Nevada below 8000 feet, where excessive rainfall may cause land/rock/mudslides. Heavy snow accumulating between 1-3 feet are possible over the higher elevations of the southern Sierra, as well as much of the Intermountain West and Central Rockies today. Snow diminishes over the Sierra on Wednesday while snow showers persist over the Colorado Rockies. Snow showers continue across the Great Lakes this week with parts of the Upper Peninsula of Michigan and downwind areas of Lake Ontario picking up between 4-8 inches of snow by Thursday morning. Troughing across the northern tier states will continue to promote below average temperatures over the next several days. High temperatures in the teens and 20s will represent a 15-25 degree departure from normal for much of the far Northern Plains today and Wednesday. A pair of mid-level disturbances are expected to phase over the Central U.S. and facilitate an arctic outbreak across the region Wednesday night into Thanksgiving Thursday. Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php