Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 259 AM EST Sat Nov 23 2024 Valid 12Z Sat Nov 23 2024 - 12Z Mon Nov 25 2024 ...Very strong Atmospheric River to produce heavy snow across the Sierra Nevada before winding down over north/central California today... ...Above average temperatures expand across the Central U.S. this weekend... Moisture associated with a highly impactful and dangerous atmospheric river event will diminish as it sags south and east through central California today. Heavy snow is likely over much of the Sierra Nevada this morning where anywhere between 1-2 feet are expected to accumulate when all said and done. Upslope portions of the Sierra below 7000 feet may experience isolated instances of flash flooding this morning before snow levels drop on the backside of the cold front pushing through the West this afternoon. Snow showers spread into Northern/Central Rockies this afternoon and the Intermountain West on Sunday. Snowfall totals of 6-12 inches are probable for the aforementioned areas by the end of the weekend. Surface high pressure extending from central Canada down to the Gulf Coast will support below average temperatures for those regions through tonight. Parts of the Southeast will experience low temperatures in the mid to upper 30s which may lead to some frost/freezes. A deepening upper trough over the north-central U.S.and Ridge over Mexico will promote above average temperatures across the Great Plains today and Sunday before expanding into the East by Monday. Elsewhere, mixed precipitation can be expected to continue across portions of upstate New York and New England today. Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php