Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 230 PM EST Thu Jan 02 2025 Valid 00Z Fri Jan 03 2025 - 00Z Sun Jan 05 2025 ...Long duration lake-effect snow event continues downwind of the Great Lakes... ...Pacific system brings another round of locally heavy coastal rains and higher elevation snow to the northwestern U.S./Rockies Friday into Saturday.... ...Arctic air surges south from the Northern Plains through the central and eastern U.S.... Strong northwesterly winds on the southwest side of a low pressure system lingering over southeastern Canada will lead to continued lake-effect snow bands downwind of the Great Lakes through the end of this week and into the weekend. The heaviest snow is expected downwind of Lakes Ontario and Erie, where total snowfall amounts in the 2-4 feet range will be possible under the most persistent bands. Some moderate to locally heavy snowfall will be possible downwind of Lakes Superior and Michigan as well, though this should taper off by Saturday. An upper-level shortwave and accompanying cold front sweeping through the Midwest will also bring some light wintry precipitation chances through Friday morning before some much more substantial accumulating snowfall in the central Appalachians into the day Friday. Winter weather-related advisories have been issued for snow totals of 6-12 inches. Snow should taper off by Saturday morning. In the West, ongoing coastal rain, a lower elevation rain/snow mix, and higher elevation snow will begin to ramp back up into Thursday evening and overnight as yet another upper-level wave/Pacific System move into the Pacific Northwest bringing additional moisture from the Pacific to the coast and inland. Locally heavy rainfall is most likely through Friday for upslope regions along the coastal ranges of southwestern Oregon and northern California as well as inland along the Sierra in northern California. Some isolated instances of flooding will be possible. Heavy, accumulating snowfall is expected in the Cascades and Sierra as well as the northern Rockies Friday, spreading into the central Rockies by Saturday as the system continues inland. Snowfall totals over a foot are likely for the higher mountain peaks. A mix of light to moderate rain and some snow will pass inland through the Great Basin Friday and Friday night, with little to no accumulations expected. Moist, upslope flow ahead of the system as it passes over the Rockies will bring some heavy, accumulating snowfall to the northern High Plains as well beginning Friday afternoon and continuing into the day Saturday. This system will lead to impactful winter weather from the central Plains eastward through the Middle Mississippi/Ohio Valleys and eventually the Mid-Atlantic mostly after the current forecast period Saturday evening, though some wintry precipitation may begin for the central Plains by late Saturday afternoon. A stagnant pattern featuring a strong upper-level low over southeastern Canada/the northeastern U.S. will begin to settle in late this week and last well beyond the current forecast period, bringing a stretch of below average, chilly Winter temperatures to much of the central and eastern U.S. These conditions are already spreading through the Northern Plains and Midwest, with forecast highs Friday in the single digits and teens in the northern Plains and the teens to 20s in the Midwest. Gusty winds will bring wind chills as low as -30 degrees for portions of the northern Plains Friday morning. The surge of colder air will reach the East Coast by Saturday with highs in the teens and 20s for New England, the 20s and 30s in the Mid-Atlantic, the 30s and 40s in the Carolinas, and the 40s and 50s in the Southeast. Highs in Florida will be in the 50s and 60s outside of South Florida, and Freeze and Frost-related advisories are in effect for the northern Peninsula as lows dropping into the low 30s could damage local vegetation. In stark contrast, conditions over the western and south-central U.S. will be above average and mild for most locations, with 40s and 50s for the Pacific Northwest and Interior West, 50s and 60s for California and the southern Rockies/Plains, and 60s and 70s in the Southwest. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php