Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 248 PM EST Wed Dec 26 2018 Valid 00Z Thu Dec 27 2018 - 00Z Sat Dec 29 2018 ...Significant post-Christmas winter storm will impact the Central and Northern Plains, and the Upper Midwest through the end of the week... ...Severe weather, heavy rain and flash flooding will be possible across portions of the Southern Plains, Lower Mississippi Valley and Central Gulf Coast states tonight and Thursday... ...Heavy rain and flash flooding will be possible by Friday across portions of the Southeast, Mid-Atlantic and the Appalachians... ...New winter storm arrives across the Southern Rockies by Friday... A storm system currently ejecting out across the southern High Plains will gradually 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 likely across a large area of the central and northern Plains, and also the upper Midwest. Blizzard conditions will be possible and this will result in hazardous travel conditions with significant impacts to road and air travel through the end of the week. Snowfall totals are expected to exceed 1 foot from areas of far northern Nebraska through eastern South Dakota and across west-central Minnesota by Friday evening. In the wake of the low center as it gradually advances northeast and into Canada will be the arrival of much colder temperatures. Cold air that is already in place across the Western U.S. will spill out into the Plains and be reinforced by cold air coming south from Canada. This will result in high temperatures of as much as 15 to 25 degrees below normal by Friday from the Four Corners region east out across a large area of the Plains. Meanwhile, on the warm side the same storm system, there will be a significant concern for severe weather, along with heavy rain and possible flash flooding. The threat will initially cover a large area of the southern Plains this afternoon and tonight, but will then shift east to include the lower Mississippi Valley and the central Gulf Coast states on Thursday as widespread showers and thunderstorms develop along and ahead of a cold front approaching from the west. In fact, the Storm Prediction Center has highlighted an Enhanced Risk of severe weather for the southern Plains through tonight, for the expectation of thunderstorms capable of producing damaging winds, large hail and tornadoes. A Slight Risk of severe weather is currently highlighted farther to the east across the lower Mississippi Valley and central Gulf Coast states for Thursday. 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. By Friday, this storm system will arrive across the Eastern U.S. along with a surge of much milder air that will result in high temperatures that are locally 20 to 25 degrees above normal. However, along with the warmer weather will be a concern for heavy rain across portions of the Southeast, the southern Appalachians and the Mid-Atlantic region. Locally as much as 2 to 4 inches of rain is expected with the heaviest amounts in the southern Appalachians. Some flash flooding will be possible as a result, and the Weather Prediction Center has also highlighted this area in a Slight Risk of excessive rainfall for this region. Also, the next winter storm will be developing across the Southwest U.S. by Friday, which will bring heavy snow again to portions of the Four Corners region and especially the southern Rockies. Locally over 1 foot of new snow will be possible, and also temperatures will remain well below normal across this region as this next storm system arrives. Orrison Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php