Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 322 AM EST Sat Dec 03 2016 Valid 12Z Sat Dec 03 2016 - 12Z Mon Dec 05 2016 ...Heavy rain possible across portions of the Western Gulf Coast to the Southeast... ...Snow for the Cascades and Northern Rockies... A deep upper-level low over Northwestern Mexico will move eastward to North-Central Mexico by Monday. The circulation around the upper low will aid in streaming moisture off the Gulf of Mexico into the Gulf Coast States that will produce showers and thunderstorms over the Western Gulf Coast that will expand eastward to the Eastern Gulf Coast by Sunday evening. Rain will also develop over parts of the Southern Plains into the Lower Mississippi Valley that will expand into parts of the Tennessee Valley by Saturday evening and move into parts of the Ohio Valley and the Central/Southern Appalachians/Southeast by Sunday evening. The rain will be heavy at times. Snow will develop over parts of the Southern Rockies into parts of the Central High Plains by Saturday morning that will wind down over the Southern Rockies by Saturday evening. In addition, rain will develop over parts of the Southwest and Southern Rockies through Saturday evening. Meanwhile, upper-level energy over the Northern Plains into the Central Rockies will move eastward to the Upper Mississippi Valley/Upper Great Lakes and parts of the Ohio Valley by Sunday evening. The system will produce rain and snow over parts of the Central Plains/Middle Mississippi Valley by Saturday evening that will become mostly snow over the Upper Mississippi Valley/Upper Great Lakes by Sunday evening. Mostly rain will move into the Ohio Valley by Sunday evening, too. Onshore flow will aid in producing rain and higher elevation snow over parts of the Pacific Northwest that will begin to move into Northern California on Sunday producing rain over parts of Northern California Sunday afternoon into evening. Furthermore, some of the moisture from the Pacific will move inland to the Northern Intermountain Region/Northern Rockies that will produce snow over the area through Sunday morning. A front will move onshore over the Pacific Northwest on Saturday evening and move inland to the Northern Rockies/Northern High Plains by Sunday evening. The boundary will aid in producing rain and higher elevation snow over parts of the Pacific Northwest on Saturday evening with snow developing over parts of the Northern Rockies by Sunday morning. The snow will continue over the Northern Rockies and move into parts of the Northern High Plains by Sunday evening. Elsewhere, upper-level energy over the Great Lakes into the Northeast will aid in producing lake effect snow downwind from the Great Lakes on Saturday that will wind down, west to east, overnight Saturday into Sunday morning. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php