Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Sat Jul 15 2017 Valid 00Z Sun Jul 16 2017 - 00Z Tue Jul 18 2017 ...Thunderstorms could become severe tonight over the upper Midwest... ...Heavy downpours possible near a stationary front across Tennessee into Mid-Atlantic as well as central High Plains... The upper-level pattern across the U.S. mainland continues to favor a trough over the eastern U.S. through the weekend. This will keep a front nearly stationary from across the southern Plains to the southern Appalachians and through the Carolinas. A hot and humid air mass together with the remnants of tropical depression Four will continue to trigger scattered showers and thunderstorms across the Deep South into early next week. Farther north, replenishing cool air from central Canada will push a cold front through the upper Midwest tonight. Thunderstorms that develop ahead of the front could become severe tonight. The front should push through the Great Lakes on Sunday before approaching the Appalachians on Monday. This will trigger showers and thunderstorms across the interior section of the Northeast and down into the mid-Atlantic. The front will begin to merge with the stationary front across the South, resulting in scattered thunderstorms over much the East Coast on Monday. Out West, a Pacific front is forecast to penetrate further inland during the weekend. This will increase the chance of scattered thunderstorms across the Intermountain region through tonight, and across the northern Rockies into the northern High Plains on Sunday. Cooler air will filter into much of the Northwest before reaching the northern Plains on Monday, which will lower the high temperatures from the triple-digits to the 90's. Farther south, monsoonal moisture along with an upper-level disturbance will trigger showers and thunderstorms over parts of the central and southern Rockies and into parts of the Desert Southwest especially during the afternoon and early evening hours through Monday. Meanwhile, showers and thunderstorms could become quite strong over the upper Midwest ahead of a low pressure wave and a frontal boundary. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php