Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 338 AM EDT Mon Jul 20 2020 Valid 12Z Mon Jul 20 2020 - 12Z Wed Jul 22 2020 ...Sweltering heat and humidity up and down the East Coast today, increasingly hot conditions in the Northwest ... ...Severe weather and flash flooding possible in central and eastern portions of the country to start the week... Stifling heat and humidity sticks around for one more day in the Northeast. Heat Advisories and Excessive Heat Warnings are in effect today from North Carolina on up the Northeast I-95 corridor where heat indices of 105 to 110 degrees are expected. A cold front sweeping through the Northeast late Monday will usher slightly cooler and less humid conditions across the region, but the front is forecast to stall over the northern Mid-Atlantic, keeping hazy, hot, and humid conditions around into Tuesday from the Mid-Atlantic to the Southeast. The heat is also expected to pickup in the Northwest where high temps range between 90 and 100 degrees across interior Washington and Oregon. The Southwest will continue to contend with above normal temperatures while the northern High Plains and Midwest witness the cooler and less humid conditions the first half of the week. The cold front responsible for bringing relief from the heat across the Northeast on Tuesday is also responsible for sparking showers and thunderstorms Monday afternoon and evening. Farther west, the front will meander over the Plains, Mississippi Valley, and Ohio Valley into Tuesday while an upper-level disturbance passes over the north-central Plains. Rain and thunderstorms could cause flash flooding over the Central Plains and Middle Mississippi Valley Monday and into Monday night. A Slight Risk for flash flooding has been issued due to the potential for heavy rainfall rates and totals with localized totals over two inches possible in these areas. In addition, strong-to-severe thunderstorms may develop over the Northern Plains where Slight risks for severe weather and flash flooding are in place. The threat for severe weather and heavy rainfall will shift to the Midwest and across the Middle Mississippi and Ohio Valleys on Tuesday with parts of the Upper Mississippi Valley under a Slight Risk for flash flooding. Elsewhere, daily episodes of monsoonal showers and thunderstorms are anticipated in the central and Southern Rockies. A cluster of showers and thunderstorms associated with a tropical wave near the Bahamas should make for a wet and stormy start to the week across far southern Florida and the Florida Keys. Mullinax Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php