Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 416 AM EDT Wed Jul 05 2017 Valid 12Z Wed Jul 05 2017 - 12Z Fri Jul 07 2017 ...A heat wave over the western U.S. is spreading into the northern High Plains... ...Potential for heavy rain moving into the mid-Mississippi Valley as strong to severe thunderstorms move across the upper Midwest... A deep-layer warm high pressure cell aloft is forecast to strengthen and dominate the western U.S. over the next few days. With the strong July sunshine, heat is expected to build across the interior sections. The Desert Southwest will see temperatures rising into the 110s daily. The hot and dry weather will spread farther north across the Inter mountains, northern Rockies, and eastward into the northern High Plains where high temperatures are expected to exceed 100 degrees today. Slightly cooler air will arrive behind a cold front tonight. This will keep high temperatures in the 90s on Thursday over the northern High Plains. A low pressure wave that is forecast to form along the front will trigger thunderstorms from across the northern Plains into the upper Midwest today. These thunderstorms could become severe over the upper Midwest into the upper Great Lakes on Thursday as the low pressure wave approaches. Meanwhile, a subtle area of low pressure has formed along a weak front in the central Plains. This low, likely resulted from the interaction of antecedent thunderstorm clusters with the weak front, is forecast to move east-northeast across the mid-Mississippi Valley today and tonight, followed by the Tennessee Valley into the central Appalachians on Thursday. The low will likely help focus and enhance showers and thunderstorms ahead of and along its path. The rain could be heavy enough to cause areas of flooding in the aforementioned regions through Thursday. By Friday morning, the system should be moving across the central Appalachians towards the mid-Atlantic region with areas of heavy rain possible. Meanwhile, a cold front will be moving across the Great Lakes with scattered showers and thunderstorms extending southwest across the Midwest and into the central Plains. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php