Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 AM EST Thu Dec 19 2013 Valid 12Z Thu Dec 19 2013 - 12Z Sat Dec 21 2013 ...Active weather expected with a Pacific system dropping through the Central Great Basin and Southwest... ...An arctic front slowing down while dropping out of the north central U.S. will bring unsettled weather from the Southern Plains to the Northeast and set up quite the dichotomy of temperature anomalies... ...Widespread moderate to heavy precipitation will move onshore with a warm front surging into the Pacific Northwest Friday into Saturday... Unsettled weather will continue with a Pacific front sinking through the southwestern corner of the Nation late this week. Accumulating snows will be possible over the higher elevations of the Central Great Basin and Sierra Nevada range...and as increasing amounts of Pacific moisture get wrapped into the system...widespread moderate to heavy precipitation is expected to develop over the Southwest. Falling temperatures across the region will make snow a possibility over portions of the Mogollon Rim. Strong winds with an arctic front dropping out of the north central U.S. will continue to force upslope snows over the Northern to Central Rockies and adjacent High Plains on Thursday. Farther east...while the front pushes through the Midwest and Central Plains...a lack of moisture will initially limit precipitation; However...as the boundary slows down and warm moist Gulf air surges northward...weather will become increasingly active along the front. A warm front moving onshore will bring moderate to heavy precipitation into the Northwestern U.S. Friday into Saturday. Steady rains are expected along the Washington and Oregon coasts...and widespread snowfall accumulations will be possible over the Cascades...Intermountain West...and Northern Rockies. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php