Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 500 AM EDT Mon Sep 07 2015 Valid 12Z Mon Sep 07 2015 - 12Z Wed Sep 09 2015 ...Heavy rain possible from the Middle Mississippi Valley to Oklahoma... An extensive cold front, extending from Quebec to the Upper Midwest and through the Central Plains, will slowly move east through Wednesday morning. The southern tail of the front will be quasi-stationary near the Central Rockies. Showers and thunderstorms will develop all along and ahead of the boundary from the Southern High Plains to the Upper Mississippi Valley/Upper Great Lakes region. A large portion of the Central Plains and Middle Mississippi Valley will have higher rainfall amounts over the course of a few days. Flash flooding will be of concern in this region through midweek. Showers and thunderstorms will fire up over the Gulf Coast, the Southeast and southern Mid-Atlantic with upper-level energy and moisture streaming into the area. Additionally, weak monsoonal moisture and daytime heating will help generate showers and thunderstorms over parts of the Southern Rockies/Southwest mainly during the late afternoon and late evening hours today. Furthermore, onshore flow from the Pacific and upper-level energy will aid in producing rain over parts of the Pacific Northwest into parts of the Northern Rockies through Wednesday. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php