Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 354 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 to 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. High pressure aloft will expand across the western U.S. through Monday, with dry conditions and rising temperatures prevailing for most areas. Isolated showers or thunderstorms will be possible each afternoon and evening in mountainous areas. Temperatures will rise substantially across much of the West by Monday, with highs soaring well into the 90s from the interior West Coast states to the Great Basin, 10 to 20 degrees above average. Highs in the California Central Valley and across portions of the Desert Southwest may surpass 110 by Monday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php