Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 334 PM EST Thu Dec 24 2015 Valid 00Z Fri Dec 25 2015 - 00Z Sun Dec 27 2015 ...Flash flooding possible across portions of the Southeast, Tennessee valley, and Appalachians... ...Heavy snow possible from portions of the Rockies into the northern plains tonight into Christmas Day... ...Snow expected to develop on Saturday from portions of the southern Rockies to the southern High Plains... The weather pattern will be rather stormy across much of the contiguous U.S. over the next few days, with heavy rain and heavy snow forecast to affect many areas. A frontal boundary will become nearly stationary tonight from the lower Mississippi valley into the Ohio valley and Mid-Atlantic, keeping scattered to numerous showers and thunderstorms in the forecast for these areas through Christmas Day. On Saturday, this frontal boundary will begin to move north as a warm front, with widespread rain and thunderstorms spreading farther north into southern portions of the Great Lakes and the Northeast. Flash flooding is possible tonight across portions of the Southeast. The threat of flooding/flash flooding will spread north across the Tennessee and Ohio valleys on Christmas Day. A low pressure system will bring heavy snow to portions of the central and northern Rockies tonight into Friday. Snowfall amounts may surpass one foot at the higher elevations. By later Christmas Day, the low pressure system will move from the Rockies into the central High Plains, spreading snow across portions of the central and northern plains, with freezing rain also possible on the southern edge of the snow area. Snowfall amounts of 4 to 8 inches are forecast from portions of the central/northern plains to the Upper Great Lakes through Saturday. On Saturday, low pressure at the mid and upper-levels of the atmosphere will strengthen rapidly across the southwestern U.S., as a new surface low develops along the frontal boundary over far western Texas. An Arctic cold front moving southward across the plains will usher a cold air mass into much of the region, setting the state for a potentially significant winter weather event starting late Saturday across portions of the southern High Plains. Snow will begin early on Saturday across the southern Rockies, before spreading into the High Plains by evening. Areas of sleet and freezing rain will also be possible by Saturday evening across portions of the southern/central plains. Please refer to products issued by local NWS Forecast Offices for details specific to your area. Temperatures are forecast to remain well above average on Christmas Day across much of the eastern half of the nation. The warmest temperatures will be along the Eastern Seaboard, where high temperatures more than 20 degrees above average are forecast. Above average temperatures will persist into the weekend from the lower/middle Mississippi valley eastward. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php