Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 325 AM EDT Thu May 21 2015 Valid 12Z Thu May 21 2015 - 12Z Sat May 23 2015 ...There is a slight risk of severe thunderstorms over parts of the Carolina Coast and the Lower Rio Grande Valley... ...Heavy rain possible over parts of the Southern Plains... ...Temperatures will be 15 to 30 degrees below average over parts of the Southern Plain/Southern Rockies... Low pressure over the Carolinas will move northeastward out over the Western Atlantic by Friday morning. The system will produce rain over parts of the Mid-Atlantic and showers/thunderstorms over the Carolinas that will move off the coast by early Friday morning. The associated front will linger over the Gulf Coast through Friday night. Moisture from the Western Gulf of Mexico will stream northward over the Plains on Thursday and Friday. Showers and thunderstorms will develop along the Gulf Coast on Thursday. In addition, showers and thunderstorms will also develop over parts of the Southern Plains well into Friday evening. Further, rain will develop over parts of the Central Rockies/Plains on Friday morning and move to the Middle Mississippi Valley by Friday evening. Meanwhile, an upper-level low off the Northern Coast of California will slowly move eastward to the Great Basin/Southwest by Friday evening. The energy along with the moisture along the West Coast and moisture spilling into the Northern High Plains will aid in producing diurnal showers and thunderstorms from parts of the Pacific Northwest/Northern California eastward to the Northern/Central Rockies through Friday evening. The precipitation will wane in area to rain with embedded thunderstorms during the morning hours. Elsewhere, a front over the Upper Great Lakes/Upper Mississippi Valley will move southeastward to off the Northeast Coast to the Central Appalachians/Ohio Valley by Friday evening. The system will produce rain over parts of the Northeast Thursday evening into Friday afternoon. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php