Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 418 AM EDT Sun Jun 18 2017 Valid 12Z Sun Jun 18 2017 - 12Z Tue Jun 20 2017 ...There is a slight risk of severe thunderstorms from parts of the Northern Appalachians/Lower Great Lakes to parts of the Ohio/Tennessee Valleys and the Lower Mississippi Valley... ...Heavy rain possible over parts of the Northeast/Northern Mid-Atlantic to parts of the Tennessee/Lower Mississippi Valleys... A front extending from the Great Lakes southwestward to the Lower Mississippi Valley and Southern Plains will move eastward to the Northeast/Mid-Atlantic Coast southwestward to parts of the Southeast/Lower Mississippi Valley and into the Southern Plains by Monday evening. The system will produce showers and thunderstorms from the Great Lakes/Upper Mississippi Valley to Western Ohio Valley/Middle Mississippi Valley into parts of the Southern Plains that will move to the Northeast Coast/Mid-Atlantic southwestward to the Lower Mississippi Valley by Monday evening. In addition, upper-level jet dynamics will aid in producing showers and thunderstorms over parts of the Northern Plains into the Upper Mississippi Valley on Sunday afternoon that will expand into parts of the Upper Great Lakes by Monday afternoon into evening. The areal coverage of the showers and thunderstorms will be at the greatest extent during the late afternoon into the late evening hours on Sunday and Monday. Meanwhile, moisture from the Gulf of Mexico and the Atlantic will extend over parts of the Southeast/Central Gulf Coast northeastward to parts of New England/Mid-Atlantic. Upper-level energy over the Lower Mississippi Valley into the Southeast with the aid of the moisture and diurnal heating will produce showers and thunderstorms over the area through Sunday evening. The showers and thunderstorms will pickup again on Monday afternoon into evening over parts of the Southern Mid-Atlantic into the Southeast and Eastern Gulf Coast. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php