Seattle, WA 14 Day Weather

Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 406 AM EDT Sat Jul 31 2021 Valid Sat Jul 31 2021 - Mon Aug 02 2021 ...Strong to severe thunderstorms with locally heavy rain from Nebraska to the mid-Mississippi Valley today should become less robust as they reach the Tennessee Valley on Sunday... ...More monsoonal moisture expected across the interior western U.S. with increasing focus over central Colorado and the northern Great Basin... ...Excessive heat continues today over the interior Pacific Northwest, the central U.S., and the Deep South before a cooling trend sets in on Sunday... A much cooler and drier airmass continues to be ushered further south into the eastern U.S. behind a departing low pressure system over the Canadian Maritimes, bringing welcome relief to the recent spell of summer heat and humidity across parts of the areas. Meanwhile, much of the heat and tropical humidity will remain across the central Plains, Deep South, and into the Southeast today where heat indices well above 100 degrees are likely. Relief is on the way for the central Plains by Monday as the cool air arrives. However, much of the Deep South will remain in the hot and humid air into Monday, only to be cooled slightly by an increasing chance of showers and thunderstorms as the front edges closer from the north. A low pressure wave developing over the central High Plains is expected to trigger organized thunderstorms that could bring isolated tornadoes, damaging wind gusts, and large hail today from Nebraska to the mid-Mississippi Valley. In addition, heavy rain associated with the thunderstorms could trigger flash flooding. Less favorable upper-level dynamics should then weaken the thunderstorms slightly on Sunday as they reach the Tennessee Valley. Meanwhile, a reinforcing push of cooler air from Canada will bring a swath of showers and some thunderstorms across the Great Lakes today, reaching western/northern New England by Monday morning. This system will attempt to merge with the aforementioned low pressure wave reaching the Mid-Atlantic coast by Monday morning to produce a period of strong to possibly severe thunderstorms near the Mid-Atlantic coast. Over the western U.S., a persistent ridge of high pressure aloft will continue to sustain the excessive heat for one more day today across the interior Pacific Northwest before the arrival of moisture from the south cools down the temperatures on Sunday. Farther south, monsoonal moisture continues to bring much needed rainfall to the drought-stricken regions of the West. This 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 today, where the threat of heavy rainfall and flash flooding will increase. The heavy rain threat over central Colorado is forecast to slide southeastward into the central High Plains on Sunday behind a low pressure wave. 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. Kong Graphics available at:
NWS Weather Prediction Center Storm Prediction Center
United States 2 Day Forecast