Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 334 AM EDT Wed May 20 2015 Valid 12Z Wed May 20 2015 - 12Z Fri May 22 2015 ...There is a slight risk of severe thunderstorms over parts of the Southern High Plains... ...Temperatures will be 15 to 25 degrees below average from parts of the Central/Southern High Plains to the Western Ohio Valley/Middle Mississippi Valley... Low pressure over the Central/Southern Plains will move eastward to the Mid-Atlantic Coast Thursday evening. The system will produce showers and thunderstorms over parts of the Lower Mississippi Valley/Southern Plains that will move to the Southern Mid-Atlantic Coast by Thursday. Rain will also develop over parts of the Central Plains/Middle Mississippi Valley that will move to the Mid-Atlantic by Thursday as well. The associated front will settle over the Gulf Coast States and moisture from the Gulf of Mexico will move northwestward into the Southern/Central Rockies overrunning the boundary. Showers and thunderstorms will develop over parts of the Southern Plains by Wednesday evening and expand northwestward over parts of the Southern/Central Rockies by Thursday evening. Meanwhile, an upper-level trough over the West Coast will be reinforced by additional upper-level energy by Thursday. Moisture along with diurnal heating will aid in produce afternoon and evening showers and thunderstorms over parts of the Pacific Northwest into California eastward into parts of the Central Rockies through Thursday. The precipitation will wane to smaller areas of rain by morning on Wednesday and Thursday. Some of the highest elevations of the Rockies will have areas of rain and snow. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php