Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 253 AM EST Sun Dec 15 2024 Valid 12Z Sun Dec 15 2024 - 12Z Tue Dec 17 2024 ...Wintry mix expected for the Appalachians Sunday with the potential for significant icing in the central Appalachians... ...Showers and storms with locally heavy rainfall possible across the Lower Ohio Valley through Monday... ...Pacific system to bring a renewed round of lower elevation/coastal rain and heavy mountain snow to the Northwest late Sunday into Monday... An upper-level wave has helped trigger a broad area of wintry precipitation this morning which will pass through the interior Northeast/Appalachians through the day Sunday. Some light snow accumulations will be possible for the central/northern Appalachians with some ice accretions expected for the southern/central Appalachians. More significant ice accretions of 0.1-0.3" are forecast for a smaller region of eastern West Virginia north through western Maryland and into southwest Pennsylvania which could cause tree and power line damage. Some lighter rain showers will be possible along the Eastern Seaboard. The wintry precipitation will lift northward into New England bringing some lighter accumulations into the day Monday. Further West, another upper-level wave/accompanying surface frontal system will better organize along the High Plains and push eastward into the Plains Sunday. Some light snow/ice accumulations will be possible northwest of the system over portions of the northern Plains through Sunday evening before shifting into the Upper Midwest Monday. To the south, moist return flow form the Gulf reaching the eastward moving frontal system will lead to increasing coverage of showers and thunderstorms across the Lower Ohio Valley southwest into the Southern Plains by late Sunday. Coverage and intensity should increase through the day Monday as the front pushes southeastward into the Tennessee Valley and Lower Mississippi Valley through Monday evening. Some locally heavy rainfall will be possible, particularly across the Lower Ohio Valley Monday. Showers are also expected to spread eastward into the Northeast Monday. Some moderate to locally heavy snow will continue through Sunday morning for higher mountain elevations of the northern Rockies/Great Basin as well as for the Cascades as an upper-level trough departs the region. Precipitation should generally tend to taper off through the afternoon. However, another Pacific system approaching the Pacific Northwest/northern California will bring a renewed round of precipitation spreading inland through the Northwest by Sunday night. Moderate to heavy lower elevation/coastal rain, a wintry mix for inland valleys, and moderate to heavy mountain snow can all be expected through Monday. The heaviest snow totals of 8-12", locally higher, are most likely from the southern Cascades/northern California east through Oregon into central Idaho and northwest Wyoming. Some gusty winds can also be expected along the Pacific Coast. Elsewhere, some showers and thunderstorms will be possible along the east coast of Florida north through the Carolinas the next couple of days. Temperature-wise, conditions will generally be at or above average for most of the country. Some of the most anomalous temperatures will be over central portions of the country, with highs in the 60s and 70s for the Southern Plains Sunday and highs into the 50s for many in the Midwest on Monday. One of the cooler spots will be along the East Coast as cold air remains in place along the Appalachians Sunday, with highs in the 30s and 40s as far south as the western Carolinas and northern Georgia. Temperatures will warm above average here as well on Monday with highs reaching into the 40s and 50s. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php