Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 243 PM EST Thu Jan 16 2025 Valid 00Z Fri Jan 17 2025 - 00Z Sun Jan 19 2025 ...Improvement in fire weather conditions across southern California... ...Arctic front to bring hazardous cold to much of the nation and impactful winter weather from the Rockies to the Northeast... Benign conditions persist across most of the country today, and fire weather conditions continue to improve in southern California as offshore winds diminish. The only precipitation of note is in the Great Lakes, central/northern Appalachians, and Mid-Atlantic where snow is falling underneath an upper shortwave. Winter Weather Advisories and Winter Storm Warnings are in effect for portions of the Appalachians where 5-10 inches of snow, falling heavy at times, is expected. Snow will continue into tonight and gradually taper off by Friday morning as the shortwave exits the region to the east. Friday will be the start of a significant shift in the weather pattern as an Arctic frontal system drops south into north-central U.S. and Northwest. The frontal system will quickly surge south and east through the weekend, reaching all the way to the Gulf and East Coasts by early next week. A frigid air mass will spread across most of the nation in the wake of the front, and temperatures will be hazardously cold for many with anomalies of 15-35 degrees below normal. The most extreme anomalies will be in the Plains, but the coldest and most dangerous temperatures will be across the northern tier. The Rockies, northern Plains, and Upper Midwest should see minimum wind chills of -30 degrees or colder through this weekend, which poses a great risk of hypothermia and frostbite to exposed skin. Subzero wind chills are forecast to reach the southern Plains, Mid-Mississippi Valley, and Ohio Valley by Sunday night. In additional to hazardous cold, the Arctic frontal system will bring wintry precipitation from the Rockies to the Northeast. Snow squalls will be possible for the Rockies and northern Plains, and brief bursts of snow and gusty winds in snow squalls could lead to reduced visibilities and deteriorating road conditions tonight through Friday. WPC has initated Key Messages for the dangerous cold and snow squall potential associated with the Arctic front. Ahead of the Arctic front, a wave of low pressure will move from the southern Plains to the Southeast Saturday into Sunday, causing a warm front to lift across these regions and trigger showers and thunderstorms. Locally heavy rainfall will be possible in stronger storms and in areas with training convection, which could lead to isolated instances of flash flooding, mainly in urban and poor drainage areas. The West Coast will largely be unaffected by this Arctic system. Temperatures should remain near normal and dry weather is expected through the weekend. Dolan Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php