Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Mon Aug 15 2022 Valid 00Z Tue Aug 16 2022 - 00Z Thu Aug 18 2022 ...Monsoonal showers and storms will keep a slight risk of excessive rainfall over parts of the Central Rockies to the Four Corners region for the next couple of days... ...A low pressure wave will likely bring heavy to excessive rainfall across the mid to lower Mississippi Valley through Wednesday... ...A tropical low pressure system could bring additional heavy downpours up the Rio Grande Valley into southwestern Texas through tonight into Tuesday... ...A slight risk of severe thunderstorms is forecast for parts of the Mid-Atlantic through this evening... ...Heat Advisories remain in effect for parts of the southern Plains/lower Mississippi Valley into this evening as and heat intensifies over the interior West Coast over the next couple of days... A front slowly dipping southward through the mid-South and down the East Coast will be the focus of addition showers and thunderstorms. As a low pressure wave over the central Plains interacts with the front, the chance of heavy rain will increase across Iowa into Missouri tonight before spreading southward through Missouri on Tuesday where areas of flooding will be possible. By Wednesday, the mid-Mississippi and Tennessee Valleys will likely see heavy rain, which will spread into the interior Gulf Coast states later that day as the low pressure wave continues to dip to the south. Meanwhile, tropical downpours associated with a tropical low pressure system is moving across southern Texas and into the lower Rio Grande Valley. As the center of tropical low appears to continue tracking west-northwest not far from the Texas-Mexican border, additional heavy rain could spread further up the Rio Grande Valley tonight and into western Texas on Tuesday. Meanwhile, monsoonal showers and thunderstorms are expected to continue from the central Rockies into the Four Corners region, where a slight risk of excessive rainfall is forecast for the next couple of days. The tropical moisture from the tropical low could across the southern borders of New Mexico and Arizona on Wednesday to raise the threat of excessive rainfall there. Farther north, the threat of heavy rain is forecast to slowly decrease as drier air filters in behind a cold front. Farther east, showers and thunderstorms along the eastern extend of the front could trigger severe thunderstorms over parts of the Mid-Atlantic through tonight. Lastly, upper-level ridging over the central Plains will contribute to more heat into tonight. On Tuesday, upper-level ridging will build into the Great Basin, allowing temperatures to rise into the mid-to-upper hundreds over parts of California, prompting an Excessive Heat Watch over the Sacramento and San Joaquin Valleys starting and over parts of the Pacific Northwest on Wednesday. Kong/Ziegenfelder Graphics are available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php