Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 215 PM EST Thu Dec 22 2016 Valid 00Z Fri Dec 23 2016 - 00Z Sun Dec 25 2016 ...Energetic storm system to bring heavy rain and snow to much of the western U.S... ...Fast-moving front to bring rain and snow to much of the central and eastern U.S... ...Above average temperatures expected for much of the central and eastern U.S... An energetic Pacific low pressure system will begin to spread precipitation into the northwestern U.S. today, with rain in the coastal Northwest and snow in the Cascades. Tonight into Friday, precipitation will become much more widespread across the West as the system begins to move inland. Rain is expected across much of California, with snow in the Sierras. Rain may be heavy across coastal areas. Heavy snow is possible across the higher elevations of California and the Pacific Northwest, as well as the Intermountain West on Friday. On Saturday the system will move east, with heavy snow possible across much of the Rockies, as well as across portions of the northern High Plains late in the day. Snow levels will lower as the upper-level trough moves inland, and snow is expected to eventually fall at all but the lowest valley elevations. Farther east, a relatively weak and fast-moving upper-level disturbance and associated surface front will bring areas of light snow and freezing rain to portions of the central/northern plains and Midwest tonight, with areas of rain farther south across the southern plains. On Friday the system will begin to pull in somewhat deeper moisture from the Gulf of Mexico, and snow is expected to become more widespread across the Great Lakes. Snow, mixed with rain in some areas, is expected to spread east into the Northeast Friday night into Saturday morning. Farther south, rain is expected Friday and Saturday from the lower and mid Mississippi valley to the Mid-Atlantic. A few thunderstorms are possible across the lower Mississippi valley, where more unstable air will be in place. Temperatures are expected to be generally above average across most of the central and eastern U.S. through Saturday. High temperatures on Friday and Saturday are expected to be 5 to 15 degrees above average for many areas. Across the West, temperatures are expected to gradually drop through the next couple days as the upper trough moves inland. By Saturday, high temperatures are forecast to be 5 to 15 degrees below average along the West Coast, as well as across the Great Basin, Intermountain West, and portions of the Southwest. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php