Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 147 AM EST Sat Dec 28 2024 Valid 12Z Sat Dec 28 2024 - 12Z Mon Dec 30 2024 ...Atmospheric river to produce heavy rain/snow across much of the Northwest... ...Severe Thunderstorm outbreak and Excessive Rainfall potential from the Southern Plains to Southeast today... ...Mild and much above average temperatures will persist across most of the country... The revolving door of mid-latitude cyclones propagating through the Pacific Northwest is likely to continue through the rest of the weekend. A deep low pressure system carrying anomalous moisture will generate heavy to potentially excessive rainfall over parts of the Pacific Northwest Coast. Parts of northern California and southern Oregon are of particular concern for flash flooding as most of the heavy rainfall is likely to focus over those areas through tonight. Things begin to dry up across the Northwest Coast on Sunday. Meanwhile, heavy snow is also likely over parts of the Cascades and Northern/Central Rockies, where anywhere between 1-3 feet of snow may accumulate by Monday morning, when snow intensity will begin to weaken considerably. Another area of concern is the Lower Mississippi Valley and Southeast, where a developing low pressure system is likely to generate a severe thunderstorm outbreak today, as well as heavy rainfall through the rest of the weekend. Today, according to the Storm Prediction Center, an outbreak of severe storms with tornadoes, wind damage, and large hail is expected from parts of the Southern Plains, into the Lower Mississippi Valley and central Gulf Coast states. Several long track tornadoes are expected. Thus, a Moderate Risk (level 4/5) of Severe Thunderstorms was hoisted. Additionally, a Slight Risk (at least 15%) of Excessive Rainfall is in effect for a similar area to the SPC Slight, but extending farther into the Tennessee Valley. Heavy rainfall and scattered to severe thunderstorms shift into the East Coast on Sunday. Temperatures will remain well above average for much of the Lower 48 this weekend. Widespread high minimum temperatures may be tied or broken across much of the Ohio Valley and interior Northeast tonight followed by the Mid-Atlantic/Northeast Coast Sunday night. Troughing and cooler conditions are projected to return to the West early next week. Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php