Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 339 AM EDT Wed Aug 20 2014 Valid 12Z Wed Aug 20 2014 - 12Z Fri Aug 22 2014 ...Slight risk of severe thunderstorms over parts of the Northern Plains... ...Heavy rain possible over parts of Lower Peninsula of Michigan and parts of the Central Appalachians... Weakening upper-level low over the Great Lakes will move slowly eastward to the Northern Appalachians by Thursday evening. Showers and thunderstorms will develop along and ahead of the associated front from the Great Lakes to the Ohio Valley/Middle Mississippi Valley moving to the Mid-Atlantic Coast while extending northwestward to the Upper Great Lakes by Thursday. Meanwhile, disorganized upper-level energy embedded in upper-level trough over the Northern Rockies will aid in producing showers and thunderstorms over parts of the Northern/Central Plains into the Northern High Plains and parts of the Northern/Central Rockies/Great Basin on Wednesday into Thursday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php