Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 252 PM EST Sat Dec 16 2017 Valid 00Z Sun Dec 17 2017 - 00Z Tue Dec 19 2017 ...Pattern change expected over the weekend... A strong upper-level trough is breaking down the ridge across the West while flattening the trough over the East. Precipitation will primarily fall from the Washington Coast to the Cascades... snowfall will be heavy over the Cascades. Accumulating snow is expected for the Northern Rockies in response to a developing surface low over the Four-Corners region and shortwave energy aloft. Deeper moisture returning northward from the Gulf of Mexico ahead of the front could fuel the development of some scattered thunderstorms, along with locally heavy rainfall at times. At this time, eastern Texas and northwest Louisiana will be where the axis of highest rainfall setups- with daily areal averages of 1 to 2 inches forecast through Tuesday. A marginal risk for flash flooding has been identified for portions of Texas and Louisiana through Monday morning. Light precipitation will spread across the northern-tier states as a surface front passes through southern Canada and the Northern High Plains. Areas downwind of the Great Lakes will have snow that is somewhat enhanced by lakes, but not like it has been this past week. Warm and dry conditions are expected for Florida and the lower elevations of the Desert Southwest and into central and southern California this weekend. Fire weather concerns will still exist across parts of California owing to the dry conditions and gusty winds. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php