Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 253 PM EST Tue Dec 25 2018 Valid 00Z Wed Dec 26 2018 - 00Z Fri Dec 28 2018 ...Significant post-Christmas winter storm is expected from the Central Plains to the Upper Great Lakes... ...Severe weather, heavy rain and flash flooding will be possible across portions of the Southern Plains and Lower Mississippi Valley... ...Some locally heavy snow is expected for the Rockies... A storm system currently moving into the Southwest U.S. will advance gradually east tonight through Wednesday bringing locally heavy snow across portions of the Intermountain West and also the Rockies. A cold front associated with the storm system will be crossing the Four Corners region, and the trend over the next couple of days will be toward notably colder temperatures across much of the West with high temperatures as much as 10 to 15 degrees below normal by Thursday. This same storm system though impacting the Southwest is expected to eject out across the southern High Plains by Wednesday night before then lift northeast toward the upper Midwest by Thursday evening. A significant post-Christmas winter storm is expected as a result with heavy snow and strong winds expected from the central Plains northeast to the upper Great Lakes region. This will result in hazardous travel conditions over a widespread area with significant impacts to road and air travel. Snowfall amounts are likely to exceed 1 foot from areas of northern Nebraska through central and eastern South Dakota by Thursday evening. Meanwhile, the same storm system will bring a threat of severe weather, and also heavy rain and possible flash flooding for portions of the southern Plains and lower Mississippi Valley from Wednesday afternoon through Thursday as widespread showers and thunderstorms develop along and ahead of a cold front. In fact, the Storm Prediction Center has highlighted a Slight Risk of severe weather across these areas for the potential of damaging winds, large hail and even some tornadoes. Heavy rainfall of as much as 2 to 4 inches can be expected with locally heavier amounts, and this will result in some concerns for flash flooding as well for the same areas seeing the threat of severe thunderstorms. The Weather Prediction Center has highlighted a Slight Risk to address the excessive rainfall threat. Colder air over the West will eject east out across the Plains in behind this storm system, but the temperatures out ahead of the advancing low center will be much above normal. This will include high temperatures across much of the Midwest rising to as much as 15 to 25 degrees above normal by Thursday. The remainder of the country should be rather quiet and dry at least through Thursday, but expect the aforementioned storm system to move into the Eastern U.S. by the end of the week. Orrison Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php