Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 220 AM EST Mon Dec 24 2018 Valid 12Z Mon Dec 24 2018 - 12Z Wed Dec 26 2018 ...Heavy snow possible for the Sierras and parts of the Great Basin... ...Heavy rain possible for parts of Northern California Coast... ...Developing storm to bring potential travel trouble over the central U.S. beginning Wednesday... Upper-level energy over the Great Lakes will move off the East Coast by Christmas morning. The energy will aid in producing snow over parts of the Great Lakes into the Central Appalachians and parts of the Northeast that will quickly end over the Appalachians by Monday afternoon. The snow will start to wane over the Upper Great Lakes by Monday evening and overnight Christmas Eve for the Lower Great Lakes into the Northeast. Rain will develop over the Northern Mid-Atlantic Coast, ending by Monday afternoon. In addition, another area of upper-level energy over the Northern Intermountain Region/Great Basin will move eastward to the Middle Mississippi Valley by Christmas morning. The energy will aid in developing snow over parts of the Northern Intermountain Region/Great Basin that will slowly dissipate by Monday evening. Meanwhile, energy over the Eastern Pacific will move onshore over California on Monday evening forming an upper-level low over Southern California/Southwest by afternoon on Christmas moving into the Southwest overnight Christmas. The developing strong storm will produce rain over parts of Northern California/Pacific Northwest Coast on Monday morning. As the storm starts to move onshore on Christmas Eve, rain will expand into Central California with snow developing over parts of the Great Basin and Oregon. Overnight Christmas Eve, snow will develop over the Sierras and farther east into the Great Basin. On Christmas morning, rain will end over parts of Northern/Central California as rain moves into Southern California. By evening on Christmas, snow and lower elevation rain will develop over parts of the Southwest. As the storm moves into the Great Basin, moisture from the Western Gulf of Mexico will flow northward over the Southern Plains and the Lower Mississippi Valley. On Christmas morning, rain will develop over parts of the Middle/Lower Mississippi Valley. Showers and thunderstorms will develop over parts of the Southern Plains by evening on Christmas while rain continues over the Lower Mississippi Valley. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php