Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 PM EST Sat Feb 15 2025 Valid 00Z Sun Feb 16 2025 - 00Z Tue Feb 18 2025 ...A life-threatening flash flooding event continues this afternoon over the lower to mid-Mississippi, Tennessee and Ohio Valleys into parts of the Appalachians with severe thunderstorms across the Deep South... ...Widespread moderate to locally heavy snowfall along with increasing winds from the the Great Lakes to New England this weekend with a swath of sleet/ice just to the south... ...Another surge of arctic air will spread southward across the northern U.S. this weekend into early next week with snow developing from the northern Rockies into the north-central Plains... ...Pacific system will bring renewed round of lower elevation coastal/valley rain and higher elevation snow to the Pacific Northwest by Sunday... A life-threatening flash flooding event continues this afternoon (Saturday) across portions of the Ohio/Tennessee/Lower Mississippi Valleys and eastward to the Appalachains. Widespread showers and thunderstorms are ongoing ahead of a potent upper-level trough and accompanying surface low pressure/frontal system with strong low and upper-level winds as well as an influx of plentiful moisture from the Gulf supporting efficient and heavy rain rates. Wind flow parallel to the eastward moving front has also supported repeated rounds of back building storms, leading to very heavy rain totals of several inches. A High Risk of Excessive rainfall (level 4/4) continues over portions of northwestern Tennessee and western Kentucky where the most significant rainfall and greatest threat for life-threatening flash flooding exists. Additional significant but more scattered instances of flash flooding are expected elsewhere across the region. In addition, there is an Enhanced Risk of Severe Weather (level 3/5) from the Storm Prediction Center across the Lower Mississippi Valley and central Gulf Coast as these intense storms will also be capable of producing strong tornadoes and large hail. The forward progression of the cold front is expected to increase heading into the evening, reducing the flooding threat as storms clear areas more quickly and transitioning the severe weather threat to damaging winds. More moderate showers will continue eastward along a lifting warm front through the Mid-Atlantic this evening and overnight. The showers and thunderstorms will spread further east towards the East Coast Sunday morning into the early afternoon, with some isolated flash flooding possible for portions of the southern Mid-Atlantic. A few more potent thunderstorms will be possible across southern Georgia and the Florida Panhandle/northern Florida where instability is higher, with a Slight Risk of Severe Weather (level 2/5) mainly for the threat of damaging winds. Storms should begin to wind down quickly by Sunday evening as the front clears the coast and moves into the Atlantic. Meanwhile, on the northern side of the system, a potent winter storm will spread from the Great Lakes into Upstate New York/New England this evening and through the day Sunday. For the Great Lakes, moderate to locally heavy snow is expected, particularly for favorable lake-effect regions along Lakes Superior and Huron, with totals of 5-10", locally 12", possible. The snow here should taper off through the day on Sunday. Snowfall will ramp up further east into Upstate New York/New England overnight Saturday into early Sunday with totals of 6-12" expected, locally higher, particularly for higher mountain elevations and for areas closer to the Canadian border. An intensifying area of low pressure will also bring very strong, gusty winds across the Northeast on Sunday, which may lead to areas of blowing snow. A transition to sleet/freezing rain will be possible for more southern areas through the day Sunday, compounding the risk for difficult travel conditions. Moderate to locally heavy snow will also be possible for higher elevations of the Appalachians, with a wintry mix likely in the transition zone across portions of the Midwest and into the northern Mid-Atlantic. Precipitation should begin to wind down Sunday evening, continuing to taper off into early Monday. Another major weather story beginning this weekend and expected to continue beyond the current forecast period into next week will be the well below average, dangerously cold temperatures overspreading much of the central and eastern U.S. as an Arctic airmass settles in following the passage of the cold front. Life-threatening cold is expected this weekend across the northern Plains and Upper Midwest where high temperatures will fail to crack 0 degrees and gusty winds will lead to windchill upwards of 60 degrees below zero. Conditions this cold can lead to frostbite in a matter of minutes. Further south, forecast highs in the teens and 20s will be common across the central Plains into the Midwest with 40s and 50s from Texas east into the Lower Mississippi Valley. More intense cold is expected here further into next week. After a mild start ahead of the front along the East Coast, colder temperatures will overspread these areas as well, with highs on Monday dropping into the 20s to 40s for the Mid-Atlantic, 40s and 50s for the Southeast, and 60s into Florida. Some lingering snow showers will continue into this afternoon over portions of the northern and central Rockies. The next round of precipitation for the West will begin this evening as a Pacific storm system approaches the Pacific Northwest, bringing lower elevation coastal rain and higher elevation mountain snow to the Pacific Northwest overnight Saturday. A lower elevation wintry mix and higher elevation snow will spread inland with the system across the northern Great Basin and into the northern/central Rockies through the day Sunday. Increasing upslope flow along and just to the east of the Rockies will also bring increasing snow chances to portions of the northern High Plains by Sunday morning and into the central High Plains by late Sunday and into the day Monday, with some moderate to locally heavy snow accumulations possible. In contrast to the north, conditions will be mostly dry for most of California, the central Great Basin, and the Southwest, with generally above average, mild conditions. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php