Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 303 PM EDT Fri Jul 30 2021 Valid 00Z Sat Jul 31 2021 - 00Z Mon Aug 02 2021 ...Strong to severe thunderstorms with locally heavy rain across parts of Nebraska tonight and then toward the Middle Mississippi Valley early on Saturday... ...More monsoonal moisture expected across the interior western U.S. with increasing focus over central Colorado and the northern Great Basin... ...Excessive heat continues for the interior Pacific Northwest, central U.S., and Deep South into the weekend before much cooler temperatures overspread these regions... A deepening low pressure system entering the Canadian Maritimes tonight will usher in a much cooler and drier airmass to the Northeast, Great Lakes, and Mid-Atlantic through the weekend. This will bring welcome relief after the recent spell of summer heat and humidity across parts of these areas. Much of the heat and tropical humidity will remain across the central Plains, Deep South, and into the Southeast this evening ahead of the trailing front. Heat indices well above 100 degrees are likely throughout these regions. Relief is on the way, but not until the end of the weekend for some as much cooler temperatures enter from the north. Meanwhile, a low pressure wave developing over the central High Plains is forecast to trigger organized thunderstorms that could become severe this evening across parts of Nebraska before moving toward the Middle Mississippi Valley into Saturday morning. Isolated tornadoes, damaging wind gusts, and large hail are possible. In addition, heavy rain associated with the thunderstorms could trigger flash flooding. Over the western U.S., a persistent ridge of high pressure aloft will continue to sustain the excessive heat across the interior Pacific Northwest through Saturday. High temperatures are forecast to reach into the upper 90s and triple digits, which equates to around 10 to 20 degrees above average. Farther south, monsoonal moisture continues to bring much needed rainfall to the drought-stricken regions of the West. The broad area of monsoonal showers and thunderstorms is expected to show increasing focus across central Colorado as well as spreading further north into the northern Great Basin during the weekend, where the threat of heavy rainfall and flash flooding will increase. Lastly, Air Quality Alerts are currently in effect for portions of Idaho, Montana, Wyoming, Colorado, Minnesota, Wisconsin, and Iowa due to smoke associated with ongoing wildfires over western North America being advected into the regions by the prevailing north-northwesterly winds. Snell/Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php