Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 523 AM EDT Fri Sep 11 2020 Valid 12Z Fri Sep 11 2020 - 12Z Sun Sep 13 2020 ...There is a slight risk of excessive rainfall over parts of the Middle Mississippi Valley... ...Temperatures will be 10 to 15 degrees above average over interior portions of the Pacific Northwest while temperatures will be 10 to 20 degrees below average over the Plains and parts of the Upper/Middle Mississippi Valley... ...Fire weather conditions improving across the western U.S. An upper-level low over the Northern/Central Rockies will aid in drawing a plume of moisture northward from the Western Gulf of Mexico over the Upper/Middle Mississippi Valley on Friday into Saturday. The upper-level dynamics associated with the upper-level low will aid in producing rain with embedded thunderstorms over the Upper/Middle Mississippi Valley and parts of the Upper Great Lakes on Friday into Saturday. The WPC has issued a slight risk of excessive rainfall over parts of the Middle Mississippi Valley. The rain associated with the system will be heavy enough to produce localized to scattered areas of flash flooding over the region on Friday into Saturday morning. The rain will move into the Upper Great Lakes later on Saturday into Sunday. Temperatures associated with the upper-level low will be 10 to 20 degrees below average over the Plains and parts of the Upper/Middle Mississippi Valley that will moderate slowly. Meanwhile, tropical moisture over the Gulf Coast and the Southeast into parts of the Mid-Atlantic with the aid of embedded impulses will produce showers and thunderstorms over the region through Sunday morning. Elsewhere, upper-level ridging will allow temperatures to become 10 to 15 degrees above average over interior portions of the Pacific Northwest. In addition, weak flow under the upper-level ridge will aid in developing areas of stagnant air prompting air quality alerts across much of the West, and dense smoke advisories over parts of California and Nevada. Improving fire weather conditions can be expected over areas of the Western U.S. through Saturday as winds should remain relatively weak, although caution should not be relaxed as the air remains very dry and winds may increase again Sunday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php