Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 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 condition 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 heavier rainfall can also be expected as low pressure waves form and travel along the stationary front. Meanwhile, the low pressure waves are forecast to interact with the upper trough as they reach the southeast U.S. 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 and being lifted along the coastal stationary front. Farther north, a reinforcing cold front is sparking showers and thunderstorms across the interior Northeast this afternoon. These storms will track east across the region this evening with damaging winds, hail, and flash flooding possible within the more intense storms. In wake of this frontal passage, a cool and dry air mass across the northern Plains will be ushered into the Great Lakes and the Northeast begin the new work week. Over the Mid-Atlantic region however, the front is forecast to stall late Monday into Tuesday, which will encourage showers and thunderstorms to stick around along the coast. More showers and thunderstorms are expected all the way down into Florida and along the Gulf Coast where the front is forecast to stall out. In the Pacific Northwest, an influx of monsoonal moisture from the south should help cool down the temperatures today across the interior sections, breaking the recent spell of excessive heat. However, there is no shortage of monsoonal moisture across the Intermountain West. The associated rainfall is a welcome sight to the drought-stricken West, 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. The Excessive Rainfall threat in Idaho and the southern High Plains this afternoon becomes more focused along the spine of the Rockies on Monday. By Tuesday, the Excessive Rainfall threat diminishes in the Northwest, but a Slight Risk remains in place in the portions of Colorado and New Mexico. In addition, hotter conditions return up and down the West Coast 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