Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 357 PM EDT Tue Jul 21 2015 Valid 00Z Wed Jul 22 2015 - 00Z Fri Jul 24 2015 ...Heavy rain possible over parts of the Southern Plains and Intermountain West... A front extending from New England through the Carolinas and into the Southern Plains will be the main feature influencing the eastern half of the U.S. much of the East Coast will see relief from the heat over the next few days as a cooler and less humid airmass moves into the area. Showers and thunderstorms will be possible along and ahead of the eastward moving front. The trailing portion of the front, specifically over the lower Mississippi Valley and the Southern Plains, will stall allowing showers and thunderstorms to focus over this area. Heavy rain and flash flooding may be possible for portions pf extreme southern Kansas, northern Oklahoma and northwest Arkansas through Wednesday morning; with the potential of heavy rain continuing into Thursday morning for the Ozark Mountains. Moisture pooling over the southeast U.S. will aid in triggering showers and thunderstorms through Wednesday as well. A front over the Pacific Northwest will slowly move eastward into the Canadian Prairie, the Northern High Plains and Great Basin by Wednesday. Showers and thunderstorms will develop along the warm front over the High Plains and advance eastward to parts of the Northern/Central Plains by Tuesday evening then fade over the Upper Mississippi Valley by Wednesday evening. Convective activity will initiate along the cold front that will sweep across Idaho and Montana Wednesday and Thursday. Pockets of heavy rain may be possible over eastern Idaho, extreme southwest Montana and northwest Wyoming. Moisture over California will trigger showers and thunderstorms over parts of Southern/Central California into parts of the Great Basin through late Tuesday night. Monsoonal moisture and diurnal heating will produce showers and thunderstorms over part of the Southern/Central Rockies through Wednesday. Campbell/Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php