Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 257 AM EST Fri Dec 22 2017 Valid 12Z Fri Dec 22 2017 - 12Z Sun Dec 24 2017 ...There is a moderate risk of flash flooding across portions of the South... ...Icy conditions along with snow may impact transportation from the Great Lakes and New England... ..Bitterly cold temperatures expected across the northern Plains and northern Rockies... Widespread showers and thunderstorms will setup over the Southern Plains, Lower/Middle Mississippi Valley and the Tennessee Valley as warm, moist Gulf air transports north ahead of a cold front. With an expected slow eastern progression with this system, an axis of higher rainfall amounts is forecast to span from southern Arkansas to southern Kentucky- invoking an area with a moderate risk for flash flooding today. As the precipitation and front shifts to the East on Saturday the area of elevated risk will setup over the eastern Tennessee Valley/central Appalachians. By Saturday afternoon, the cold front quickly moves toward the East Coast. Rainfall will still occur along and ahead of the front by Saturday afternoon albeit not nearly as heavy. A clipper system will drop through the Northern and Central Plains which will reinforce cold air over the central U.S. and the Great Lakes region. This does not bode well for travel over the next few days as precipitation will likely be a mix of ice and snow from the Great Lakes to New England. Freezing rain along with snow will spread northward across the Northeast today and into Saturday morning as the frontal boundary lifts north. Please see WPC's winter weather products and discussion for more information pertaining to the winter weather hazards associated with this system. Arctic air will surge southward along the Northern Rockies and into the Northern Plains. Temperatures across this sector will plummet into the teens above zero, which on average will be 20 degrees below normal for late December. Locations ahead of the cold front pressing eastward from the Plains to the East Coast--high temperatures will be about 15 degrees above normal. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php