Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 430 AM EDT Mon Aug 02 2021 Valid 12Z Mon Aug 02 2021 - 12Z Wed Aug 04 2021 ...Showers and thunderstorms linger along the Coast Coast and Southeast as threat of heavy rain increases near the Carolina coasts... ...Monsoonal rainfall gradually shifts eastward from the Intermountain West to the spine of the Rockies... ...A cool regime is expected to dominate much of the central and eastern U.S. as heat returns for the interior Northwest and northern Plains... A broad upper level trough settling across the central to eastern U.S. will provide an extended period of cool and dry conditions for much of these areas today. Meanwhile, the recent oppressive heat across the Deep South will be cooled by more numerous showers and thunderstorms today as a cold front slowly edges in from the north. The front is forecast to reach the Gulf Coast on Tuesday and then becomes nearly stationary. This will allow the showers and thunderstorms to linger along the Gulf Coast into Wednesday. Episodes of locally heavier rainfall are possible as low pressure waves form and travel along the stationary front. The low pressure waves are forecast to interact with the upper trough as they move toward the southeast U.S. later on Tuesday. This regime will allow the threat of heavy rain to increase near the Carolina coasts later on Tuesday into Wednesday as the influx of Atlantic moisture increases while being lifted along the stationary front. Some enhanced rainfall could push further inland across the central and southern Appalachians by Tuesday. Meanwhile, the chance of showers and thunderstorms will increase farther south into Florida over the next couple of days. In the western U.S., monsoonal rainfall has been a welcome sight for the drought, but downpours associated with some thunderstorms are capable of producing heavy rainfall rates that could trigger areas of flash flooding. Locations most at risk for flash flooding are where antecedent soil conditions are overly saturated or near burn scars. Over the next couple of days, the focus of the monsoonal rainfall is forecast to gradually shift from the Intermountain/Great Basin region eastward to mainly along the spine of the Rockies as an upper ridge re-establishes over the Desert Southwest. By Wednesday, the monsoonal rain should be confined to the vicinity of the central and southern Rockies. The drying trend along the West Coast will allow the heat to return for the interior sections on Tuesday. Air Quality Alerts remain in effect for portions of the interior Northwest, Arizona, Colorado, Wyoming, and the upper Midwest due to smoke associated with wildfires over western North America being transported into these areas. Kong/Mullinax Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php