Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 301 PM EST Thu Jan 01 2015 Valid 00Z Fri Jan 02 2015 - 00Z Sun Jan 04 2015 ...A significant winter storm will impact the Southern High Plains to the Midwest through this weekend... ...Heavy and potentially excessive rainfall will affect the Lower Mississippi and Tennessee Valleys... An upper level low pressure center over Arizona which helped drive the significant surge of cold air into the southwest U.S. over the last couple of days will slowly advance east and should move out into the Southern and Central Plains by late in the weekend. The result is expected a rather significant multi-day winter storm that will drive a large area of snow and especially sleet and freezing rain from the Southern High Plains northeast to gradually including much of the Midwest by late in the weekend. Low pressure forming over the Lower Mississippi Valley early Saturday will allow a significant surge of Gulf of Mexico moisture to stream north and overrun much of the Gulf Coast states and into the Tennessee Valley. This should foster a widespread area of moderate to heavy rain along with embedded thunderstorms. Some of the rainfall may be heavy enough to cause some flash flooding concerns, and especially for the central Gulf Coast region. Meanwhile, an arctic cold front over the northern tier states will move eastward across the Great Lakes and the Northeast through Friday which will reinforce colder temperatures and also afford some lake effect snow shower activity. This will end over the weekend and temperatures, especially over the Great lakes and Ohio Valley will begin to warm up ahead of the developing storm system over the Southern Plains and Lower Mississippi Valley. Much milder temperatures should then overrun the Southeast and Mid-Atlantic region on Sunday. In behind the aforementioned storm system developing over the South, a new surge of arctic air will impact the Northern High Plains beginning Saturday and then surge south and east through the Central Plains and the Upper Midwest Saturday night and Sunday. The next surge of arctic air will yield sub-zero temperatures, especially for the Northern Plains, and strong winds that will foster dangerously cold wind chills. This cold air banking up against the higher terrain of the Northern Rockies and will help also foster a new round of upslope snowfall which will spread out into the High Plains. Orrison Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php