Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Sat Mar 15 2025 Valid 00Z Sun Mar 16 2025 - 00Z Tue Mar 18 2025 ..Heavy snow moving into the Cascades and northern Intermountain region as a quick round of light to moderate snow impacts the central Great Lakes on Sunday... ...A Moderate Risk of excessive rainfall continues through tonight for parts of the Ohio/Tennessee Valleys edging close to the southern Appalachians... ...There is a Moderate to High Risk of severe thunderstorms across the Deep South through tonight... ...A Slight Risk of severe thunderstorms is forecast for the Mid-Atlantic to the Southeast on Sunday... A large and intense low pressure system interacting with a hyperactive upper-air weather pattern will deliver more widespread hazardous weather across the eastern half of the country through the remainder of the weekend into Monday as an atmospheric river event reaches into the Pacific Northwest. While the center of the first piece of the intense cyclone begins to track northeastward away from the upper Great Lakes, a wave of low pressure is currently rapidly developing over the Deep South along the front trailing south from the first cyclone. This low pressure wave is forecast to develop into another intense cyclone and track rapidly northeast across the Ohio and Tennessee Valleys tonight, reaching the lower Great Lakes on Sunday. This second phase of the storm will deliver an outbreak of severe thunderstorms accompanied with large hail, life-threatening tornadoes, as well as damaging winds across the Deep South through tonight. Meanwhile, a heavy rain event is emerging farther north across the Tennessee to Ohio Valleys ahead of the intensifying cyclone and a potent cold front trailing south from the cyclone. By Sunday, the potent cold front will be sweeping across the entire East Coast region where thunderstorms could rapidly develop and reach severe levels especially from the afternoon into the evening hours across the Mid-Atlantic states down into the Southeast. In the meantime, a quick round of light to moderate snow is expected to impact the central Great Lakes on Sunday as colder air rushes in behind the intensifying cyclone. By Monday, the threat of severe weather will end along the East Coast but the front will slow down just off the East Coast, allowing clouds and rain to linger near the coast, especially across much of New England. Some wet snow may mix in with the rain near the Canadian border in Maine as colder air will be ushered into the East Coast behind the front. Meanwhile, unsettled weather across the Pacific Northwest will culminate with the arrival of an atmospheric river event across Oregon into northern California by tonight. The system associated with this event will deliver a few feet of new snow for the Cascades through the next couple of days. For the lower elevation of southwestern Oregon into northwestern California, locally heavy rain pushing onshore by the atmospheric river could exceed 5 inches at some locations, which would lead to concerns of flash flooding, mudslides and river runoffs. By Monday, the entire system is forecast to slide southeastward into California, bringing an additional two feet of new snow possible for the Sierra Nevada with rain near the coast. Snow will then penetrate further inland and begin to impact the higher-elevations of the Great Basin on Monday. Meanwhile, mountain snow will continue across Idaho through the rest of the weekend and begin to spread into the northern Rockies with the passage of a Pacific cold front on Monday. Across the mid-section of the country, after a rapid cool-down behind the deep cyclone on Sunday, a rapid warm-up is expected across the northern and central Plains on Monday when another low pressure system is predicted to develop over the northern High Plains. Fire danger will once again be a concern across the central and southern Plains as dry winds from the west and southwest develop. Kong Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php