Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 518 AM EDT Sun Aug 16 2020 Valid 12Z Sun Aug 16 2020 - 12Z Tue Aug 18 2020 ...Widespread record heat continues across the western U.S. as heat moderates over the southern Plains... ...A developing low pressure system will bring areas of heavy rain today across the northern Mid-Atlantic before skirting south of Long Island tonight... A strengthening ridge of high pressure aloft will ensure a heat wave to continue across much of the western U.S. for the next few days. Excessive Heat Warnings and Heat Advisories continue to be in effect for much of the area except the Sierra Nevada. Record high temperatures are forecast for many locations for the next few days as afternoon temperatures surpass the century mark from the interior Pacific Northwest down to the Desert Southwest. The persistent heat and dry conditions will also promote wildfires across the region. The southern Plains will also see triple-digit temperatures today. But cooler air behind a cold front will drop temperatures by about 10 degrees on Monday. Meanwhile, the heat should culminate today for the interior Pacific Northwest with very slow improvement setting in for the next couple of days. In the East, a low pressure wave is currently developing just off the Mid-Atlantic coast on a stalled front. This has helped organize an area of moderate to heavy rain across the interior Mid-Atlantic region early this morning. With the ground saturated by antecedent heavy rains, flash flooding will remain a concern in this region through this morning before the rain gradually moves off the coast later today. The latest model guidance suggests that the low pressure wave could intensify more rapidly than previous forecasts. This could bring an increasing threat of heavy rain and gusty winds along the southern New England coast tonight as the intensifying low pressure system is forecast to pass just to the south. Cooler air behind the storm will filter briefly into the Eastern Seaboard tonight but an approaching cold front will help trigger scattered afternoon showers and thunderstorms from the Northeast to the Carolinas on Monday. In the Nation's Heartland, the trailing portion of the cold front will trigger scattered thunderstorms this afternoon and tonight over the central to southern High Plains. The thunderstorms should weaken and then push farther south through Texas on Monday and Tuesday ahead of the advancing cold front. Elsewhere, a weak low pressure center forming along a reinforcing frontal system will trigger a few thunderstorms over the central Plains on Monday and into the Midwest on Tuesday. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php