Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 440 AM EDT Sat Aug 08 2015 Valid 12Z Sat Aug 08 2015 - 12Z Mon Aug 10 2015 ...There is a slight risk of severe thunderstorms over parts of the Central and High Plains and the middle Mississippi Valley... ...Heavy rain possible over parts of the Northern Plains and the Middle Mississippi Valley on Saturday, with excessive rain possible for Illinois and Indiana on Sunday... There are two main frontal systems that will affect the continental U.S. through the weekend. The first extends from parts of the Upper Great Lakes/Upper Mississippi Valley southwestward to the Northern Rockies/High Plains. Showers and thunderstorms will develop along this system as it moves through the High and Central Plains. The Storm Prediction Center has highlighted extreme SE Montana/NE Wyoming/W South Dakota, E Colorado/W Kansas and NE Kansas/E Nebraska/N Missouri/ S Iowa as areas with a slight risk for severe thunderstorms to develop through early Sunday morning. The other frontal system extends from the Southeast into parts of the Central Plains/Lower Mississippi Valley also through Monday morning. Showers and thunderstorms will develop along and near the boundary from parts of the Southern Mid-Atlantic into parts of the Southeast/Eastern Gulf Coast. Showers and thunderstorms will also develop over parts of the Central Plains/Middle Mississippi Valley from through Monday morning. Portions of the Pacific Northwest and British Columbia will have rain showers as a weakening front moves toward shore. Locations along the Coastal Mountains will have more widespread coverage than the surrounding area. Additionally, monsoonal moisture and daytime heating will aid in producing showers and thunderstorm over parts of the Great Basin into parts of the Southern/Central Rockies during the afternoon and evening hours this weekend. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php