Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 242 AM EST Fri Dec 16 2016 Valid 12Z Fri Dec 16 2016 - 12Z Sun Dec 18 2016 ...Active weather pattern to continue through Saturday... The weather pattern going into the upcoming weekend will be active with a strong low pressure system currently over the Intermountain West forecast to move eastward. A fresh surge of arctic air is flowing southward from western Canada and this will reinforce the very cold conditions already in place across the northern tier states. The arctic front will join forces with the low pressure area exiting the Rockies on Friday and spawn a new surface low over the Central Plains. A huge temperature gradient is expected across the Plains and Midwest, with mild temperatures across the southern Plains and Deep South, and frigid temperatures north of the front. The very cold weather currently across the eastern U.S. is expected to modify quite a bit by Saturday as the aforementioned storm system across the Plains lifts northeastward towards the Great Lakes region. The warming trend will likely be heralded by some wintry precipitation Saturday morning across parts of the Mid-Atlantic region and the Northeast, before changing to rain later in the day. Some cold air damming is likely near the Appalachian Mountains with a shallow layer of cold air in place on Saturday, before strong southerly winds aloft erode this cold layer by Saturday evening. A brief period of mild weather can be expected Saturday night and early Sunday before colder weather arrives in time for the beginning of the work week for the East Coast. A large surface high should establish residence across much of the central U.S. on Sunday and also across much of the West. Once the front clears the coast, a quieter weather pattern is likely to commence. D. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php