Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 349 AM EDT Sun Sep 11 2016 Valid 12Z Sun Sep 11 2016 - 12Z Tue Sep 13 2016 ...Temperatures will be 10 to 20 degrees below average over parts of the Northern High Plains and Northern Rockies... A front extending from the Northeast southward to parts of the Mid-Atlantic then roughly southwestward to the Western Gulf Coast will move off the Northeast/Mid-Atlantic Coast by Sunday evening. The southern part of the boundary will dissipate by Monday evening. Showers and thunderstorms will develop along and near the boundary from parts of the Central Appalachians into the Northeast that will move off the Northeast/Mid-Atlantic Coast by Sunday evening. Showers and thunderstorms will develop over the Carolinas overnight Sunday and continue into Monday evening. Meanwhile, moisture off the Gulf of Mexico will stream into the Gulf Coast States by Sunday evening. Upper-level energy over parts of the Lower Mississippi Valley will interact with the moisture to produce showers and thunderstorms from the Lower Mississippi Valley to the Southeast Sunday evening into Monday evening. In addition, a second front extending from the Northern High Plains/Northern Rockies to parts of the Great Basin will move eastward to the Upper Great Lakes to the Central High Plains into parts of the Great Basin by Monday evening. The system will produce rain over parts of the Northern Rockies/Northern High Plains by Sunday evening. The rain will expand along the boundary over parts of the Northern Plains by Monday morning and into parts of the Upper Mississippi Valley by Monday evening. Additionally, overnight Sunday wet snow will develop over some of the highest elevation of the Northern Rockies into Monday evening. Elsewhere, monsoonal moisture and daytime heating will aid in producing showers and thunderstorms over parts of the Southwest/Eastern Great Basin into parts of the Southern/Central Rockies on Sunday afternoon into late evening and Monday afternoon into late evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php