Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 AM EDT Fri May 18 2018 Valid 12Z Fri May 18 2018 - 12Z Sun May 20 2018 ...There is a slight risk of severe thunderstorms over parts of the Central/Southern Plains... ...Heavy rain possible over parts of the Central Plains and over the Mid-Atlantic southward to the Southeast... ...Temperatures will be 10 to 20 degrees below average over parts of the Northern High Plains... Upper-level energy over the Middle/Lower Mississippi Valley will slowly move northeastward to the Ohio Valley while weakening by Saturday evening. The system will produce rain and thunderstorms over parts of the Lower/Middle Mississippi Valley eastward to the Mid-Atlantic and the Southeast that will move northward into the Great Lakes/Northeast while continuing over Ohio Valley/Mid-Atlantic and the Southeast through Saturday evening into Sunday. Meanwhile, a second area of upper-level energy and associated deep upper-level trough over the Great Basin into the Northern Plains will produce a region over rain and thunderstorms over parts of the Northern High Plains into parts of the Northern/Central Plains and the Upper Mississippi Valley will continue over parts of the region through Saturday evening. In addition, diurnal heating will aid in producing showers and thunderstorms over parts of the Southern/Central High Plains during the late afternoon into late evening on Friday and Saturday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php