Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 306 AM EST Sun Dec 29 2024 Valid 12Z Sun Dec 29 2024 - 12Z Tue Dec 31 2024 ...Atmospheric river to produce heavy rain/snow across much of the Northwest today... ...Severe Thunderstorms and Excessive Rainfall concerns shift into parts of the Central/Southern Appalachians and Mid-Atlantic/Southeast today... ...Much above average temperatures continue across the Central and Eastern U.S.; cooler air moves into the Northwest on Monday... ...Critical Fire Weather expected for portions of the Southern High Plains on Monday... An active weather pattern will continue in the northwestern and southeastern quadrants of the country today. Heavy rain associated with an atmospheric river event will produce 1-2 inches over coastal areas of Oregon and northern California, including upslope areas of the northern Sierra Nevada. Slight Risks of Excessive Rainfall (at least 15%) leading to Flash Flooding are in effect for portions of southwest Oregon/northwest California and the northern Sierra today. This wet pattern in the West could produce rock, mud and land slides over vulnerable soils. Additional heavy snow is likely over much of the Cascades, Northern/Central Rockies and Sierra Nevada. Between 1-2 feet of snow (isolated higher) are expected for parts of the Cascades and Rockies. Storms associated with a severe weather outbreak that occurred across the Southern Plains and Lower Mississippi Valley yesterday will spread into the southeastern U.S. today. Heavy rain and scattered to severe thunderstorms, capable of producing tornadoes, damaging wind gusts and hail are possible from the eastern Gulf Coast northward into the Carolinas, where a Slight Risk of Severe Thunderstorms (level 2/5) is in effect. Rain showers will also spread into the Northeast today as well, while some light wintry precipitation develops over parts of the Lower Peninsula of Michigan tonight. Meanwhile, ongoing moderate to heavy rainfall along a narrow axis of low level convergence may persist into this afternoon over south Florida. There's potential for this Marginal Risk (at least 5%) of Excessive Rainfall to over perform given current conditions. Much above average temperatures from the Central to Eastern thirds of the country should persist until Tuesday, while an increasingly trough-y pattern in the West will promote cooling temperatures beginning on Monday. Widespread high minimum temperatures may be tied or broken across the Northeast tonight ahead of a deepening upstream trough and southerly flow along a strong surface warm front. Dry, windy and mild conditions in the Southern High Plains will support a Critical Risk of Fire Weather on Monday. Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php