Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 309 AM EST Sat Feb 03 2024 Valid 12Z Sat Feb 03 2024 - 12Z Mon Feb 05 2024 ...Showers and thunderstorms Saturday for the Lower Mississippi Valley, with the risk of scattered flash flooding along the Gulf Coast... ...Moderate to heavy snowfall Saturday for portions of the Northern/Central Rockies and eastern Great Basin... ...Strong Atmospheric River to bring a considerable risk for flash flooding and very heavy snow to California beginning Saturday night... ...Mild, well above average temperatures will persist across central portions of the country this weekend... Widespread, organized showers and thunderstorms will continue eastward from the Southern Plains into the Lower Mississippi Valley Saturday ahead of a deep upper-level trough/closed low and accompanying surface frontal system. Strong southerly flow ahead of the front will funnel warm, moist Gulf air northward helping to fuel some heavier downpours, particularly for locations along the Gulf Coast. A Slight Risk of Excessive Rainfall (level 2/4) has been outlined for this region as the heavy downpours, and the threat for some repeated/training storms, will bring the risk of some scattered instances of flash flooding. Storm chances will shift into the Southeast and Florida Sunday with a continued chance for moderate to locally heavy rainfall, and the threat of an isolated instance or two of flash flooding. To the West, moderate to heavy snow showers will continue over portions of the Northern/Central Rockies and eastern Great Basin Saturday as moisture wraps northwestward around the system over the Plains and the accompanying upper-level trough lingers over the region. Many of the higher elevations of the regional mountain ranges will see totals between 5-10". Some moderate rain/snow showers will also be possible for the adjacent High Plains, with the chance for accumulating snowfall increasing for areas immediately along the Front Range from southern Wyoming southward into Colorado. The snow should begin to taper off from south to north overnight Saturday into the early morning hours Sunday, lingering longest for the Northern Rockies where a slow moving front pushing into the region will keep at least light snow chances up into the day Sunday. Attention then turns to California as a strong Atmospheric River will bring the threat for considerable flash flooding along the coast and very heavy, mountain snow in the Sierra. Rainfall is expected to begin as early as late Saturday night for central portions of coastal California where a few inches of rain by early Sunday morning may lead lead to some initial instances of flooding, and a Slight Risk of Excessive Rainfall is now in effect. The impacts will ramp up quickly during the day Sunday as the deep Pacific moisture associated with the system overspreads the region. The combination of favorable onshore/upslope flow along the coastal mountain ranges; warm, moist air keeping snow levels high; and repeated rounds of storms will lead to the threat of rainfall totals of 5"+ and rainfall rates of 1" per hour. A Moderate Risk of Excessive Rainfall (level 3/4) is in effect for coastal portions of central and southern California as these heavy rain totals will bring a considerable risk for flash and urban flooding as well as the threat for debris flows and mudslides. A Slight Risk is also in effect inland for portions of central California, especially along the Sierra where the higher snow levels will increase the threat for flooding for favorable upslope areas. For the higher elevations of the Sierra above 5000-6000 feet, very heavy, disruptive snowfall of several feet is forecast. In addition to the heavy rain and snow, very strong, gusty winds and damaging high surf are also expected. All associated impacts will continue into Monday/Tuesday beyond the current forecast period. Meanwhile, central portions of the country will have an amplified upper-level ridge in place that will maintain well above average, mild Winter temperatures for the Northern/Central Plains and the Midwest this weekend. Daily maximums will be in the 40s for the Northern Plains and the Great Lakes and the 50s from the Central Plains east through the Middle Mississippi and Ohio Valleys. While not quite as anomalous, highs elsewhere in the central/eastern U.S. will still be at or above average, with 30s and 40s for the Northeast, 50s for the Carolinas, and 60s in the Southeast and Southern Plains. The storm system and precipitation moving into the Southeast will bring some cooler temperatures Sunday, dropping highs into the 40s and 50s. Temperatures will remain on the cooler side of average across much of the West given upper-level troughing, cloud cover, and precipitation, with highs mainly in the 40s for the Great Basin, 50s for the Pacific Northwest and northern California, and 60s for the Desert Southwest and southern California. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php