Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 406 AM EDT Wed Jul 20 2016 Valid 12Z Wed Jul 20 2016 - 12Z Fri Jul 22 2016 ...There is a slight risk of severe thunderstorms across parts of the Northern Plains into the Upper Mississippi Valley... ...Temperatures will be 10 to 15 degrees above average over parts of the Northern/Central High Plains... A wave of low pressure over the Northern Plains will move eastward to the Upper Great Lakes by Thrusday evening. The system will produce showers and thunderstorms from the Upper Mississippi Valley southeastward to the Western Ohio Valley through Wednesday afternoon into evening. On Wednesday afternoon, the showers and thunderstorms will begin to expand into parts of the Upper Great Lakes. Overnight Wednesday, showers and thunderstorms will develop over parts of the Northern Plains into the Upper Great Lakes. By Thursday evening, the showers and thunderstorms will end over the Northern Plains/Upper Mississippi Valley, while expanding into the Great Lakes. Meanwhile, tropical moisture over the Gulf Coast States and extending into parts of the Southern Mid-Atlantic Coast along with daytime heating will produce showers and thunderstorms from the Western Gulf Coast to the Southeast and into parts of the Southern Mid-Atlantic Coast with a maximum in areal coverage during the afternoon into the late evening on Wednesday and Thursday. In addition, monsoonal moisture and daytime heating will produce showers and thunderstorms over parts of the Southwest/Eastern Great Basin and parts of the Central/Southern Rockies on Wednesday and Thursday afternoon into late evening. Elsewhere, onshore flow develop along parts of the Pacific Northwest Coast on Thursday afternoon will aid in producing showers and thunderstorm slightly inland from the Pacific Northwest Coast by Thursday evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php