460 FXUS01 KWBC 242021 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 320 PM EST Wed Dec 24 2025 Valid 00Z Thu Dec 25 2025 - 00Z Sat Dec 27 2025 ...Life-threatening flash flooding continues over Southern California today and tomorrow; heavy mountain snow and high winds also ongoing... ...Impactful wintry weather to spread from the Upper Midwest into the Mid-Atlantic/Northeast Friday... ...Unseasonable, record breaking warm weather continues across the Nation's mid-section through Christmas into this weekend... This afternoon, an analysis of our weather pattern across the Lower 48 highlights an anomalous mid-level high pressure ridge anchored over the Nation's Heartland, which is flanked by an equally amplified trough over the Eastern Pacific. Unfortunately, this configuration will maintain life-threatening atmospheric river conditions focused over Southern California through Christmas day, where widespread flash flooding is underway amid persistent 0.5" to 1"/hour rainfall rates. Accordingly, a rare High Risk of Excessive Rainfall remains in effect through tomorrow morning over Southern California, which includes the Los Angeles metropolitan area. Flash/urban flooding aside, the barrage of heavy rainfall will also lead to dangerous rock/mud slides across Southern California through Christmas day. Users in the affected area are encouraged to have multiple ways of receiving warning information, NEVER drive through flooded roads, and be aware that the threshold for the aforementioned impacts will decrease as additional rain falls through tomorrow. Widespread power outages and tree damage are also to be expected, owing to the combination of strong wind gusts and saturated soils across the area. Outside of the High Risk, adjacent areas in Northern/Central California (including the Bay Area) and Southern Nevada (including Los Vegas) can also expect scattered instances of flash flooding through tomorrow. In the mountains of the Sierra Nevada, snowfall totals measured in feet will ensure travel over passes is impossible through this week. Meanwhile, wintry weather is forecast to race across portions of the Upper-Midwest as a developing frontal low migrates eastward from the Dakotas into the Upper Great Lakes early Friday morning. An influx of warm air drawn northward atop a shallow sub-freezing airmass will lead to increasing coverage of impactful freezing rain along the northern flank of this low track from Northern Minnesota into the Ohio Valley, Mid-Atlantic, and Northeast by Friday evening. As of this afternoon, freezing rain amounts are expected to focus along a line roughly from Lower Michigan (including Detroit) into Northwest Pennsylvania, where upwards of a quarter of an inch of ice is forecast. However, areas in the Central Applachains and Mid-Atlantic (including Washington D.C, Baltimore, and Philadelphia) could also see a glaze of ice from this event. Over portions of Central Pennsylvania and Southern New York, 4 to 6 inches of snow remains a possibility. A look at the Watch-Warning map this afternoon depicts a swath of Winter Storm Watches over the Northeast in advance of this event, which could be quite impactful for any post-holiday travel plans. In stark contrast to the cold and wintry weather mentioned above, much of the Nation's mid-section can expect an unseasonably warm Christmas beneath the mid-level ridge. Forecast highs for tomorrow call for temperatures in the 70's and low 80's for the Central and Southern Plains, which is expected to break many daily high temperature records. In fact, record breaking high temperatures are expected to stick around through the weekend with all of the cold Polar air relegated to the Northern Tier for the time being. Asherman Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$