Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 250 PM EST Sat Jan 20 2024 Valid 00Z Sun Jan 21 2024 - 00Z Tue Jan 23 2024 ...Heavy snow for the Sierra Nevada Mountains and Higher elevation snow across the West; Lake-effect snow downwind from the Great Lakes and upslope snow for the Central Appalachians on Sunday... ...There is a Slight Risk of excessive rainfall over parts of Northern California, Southern California, and over the Western Gulf Coast/Lower Mississippi Valley... ...Rain/Freezing Rain over parts of the Pacific Northwest and the Northern High Plains and heavy rain/freezing rain over parts of the Southern Plains, Lower/Middle Mississippi Valley... High pressure over the Middle Mississippi Valley will slowly move eastward to the Mid-Atlantic Coast by Monday evening. Cold air associated with the high will create temperatures 20 to 30 degrees below average from the Central/Southern Plains, Middle Mississippi Valley, and Ohio/Tennessee Valleys. Upper-level energy over the Great Lakes, Ohio Valley, and Mid-Atlantic will produce lake-effect snow downwind from the Great Lakes through Sunday evening. There will also be upslope snow over parts of the Central Appalachians and the Northeast. Multiple fronts will move onshore over the West and dissipate over the next few days. The systems will produce heavy snow over the Sierra Nevada Mountains and the highest-elevation snow over the West, extending into the higher elevations of the Southwest. In addition, a plume of moisture will move over parts of Northern California, producing heavy rain from Saturday into Monday. Therefore, the WPC has issued a Slight Risk of excessive rainfall over parts of Northern California into Sunday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, small streams, narrow canyons/gullies, and burn scars the most vulnerable. Moreover, on Sunday, the threat of excessive rainfall continues over Northern California. Therefore, the WPC has issued a Slight Risk of excessive rainfall over parts of Northern California from Sunday into Monday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, small streams, narrow canyons/gullies, and burn scars the most vulnerable. On Monday, the plume of moisture will stream into Southern California, producing heavy rain. Therefore, the WPC has issued a Slight Risk of excessive rainfall over parts of Southern California on Monday. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, small streams, narrow canyons/gullies, and burn scars the most vulnerable. Furthermore, warmer air associated with the plume of moisture will contribute to rain/freezing rain over parts of the Pacific Northwest in the region of the Columbia Gorge through Monday. In addition, rain/freezing rain will develop over parts of the Northern Plains on Monday. Elsewhere, the flow around the area of high pressure over the Eastern U. S. will stream moisture northward from the Western Gulf of Mexico combined with upper-level energy, which will aid in producing rain over parts of southern Texas on Sunday. The moisture will continue to flow northward over the Southern Plains and Lower Mississippi Valley into the Great Lakes on Monday. The moisture flow will also produce showers, thunderstorms, and heavy rain over parts of the Western Gulf Coast and Lower Mississippi Valley. Therefore, the WPC has issued a Slight Risk of excessive rainfall over parts of the Western Gulf Coast and Lower Mississippi Valley on Monday. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, and small streams the most vulnerable. Meanwhile, the moisture flows northward into the cold air over the country s middle part, producing heavy rain/freezing rain over parts of the Southern Plains, Lower/Middle Mississippi Valley on Monday. Additionally, light rain/freezing rain will develop over parts of the Western Ohio Valley into The Great Lakes. Ziegenfelder Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php