Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Mon Aug 09 2021 Valid 00Z Tue Aug 10 2021 - 00Z Thu Aug 12 2021 ...Heavy rain and severe storms possible in the Midwest and Great Lakes through Tuesday; severe weather returns to the Northern Plains today... ...Above average heat and humidity to remain across portions of the Southern Plains into the Midwest, while temperatures climb across the Pacific Northwest... ...Poor air quality due to wildfire smoke will remain out West into parts of the Central Plains and Midwest... Severe thunderstorms and possible flash flooding will impact portions of the Northern Plains and Midwest through tonight near a pair of frontal boundaries in the area. Anomalously high temperatures combined with dewpoints that are well in the 70s were in place along and to the south/east of these frontal boundaries supporting heat indices between 100 and 110 degrees. Heat Advisories were in effect for eastern portions of the Central and Southern Plains to just across the Mississippi River. A front extending from the Great Lakes region into the Central Plains on Tuesday will support additional potential for severe thunderstorms and flash flooding, with the focus for severe storms setting up in the vicinity of eastern Iowa, southern Wisconsin and northern Illinois where the Storm Prediction Center is highlighting an Enhanced Risk for severe thunderstorms on Tuesday. Heat indices on Tuesday may breach 110 degrees across eastern Kansas into the Upper Midwest. The upper level pattern will evolve through mid-week such that the front over the Great Lakes to Central Plains will lose definition while another cold front drops down from Canada into the north-central U.S. Tuesday evening into Wednesday. The pattern will favor wildfire smoke from the western U.S. to advance downstream into the Central Plains and Midwest, resulting in reduced air quality through at least Tuesday evening. Across the northwestern U.S., high temperatures are forecast to climb through Wednesday with highs nearing 100 degrees in Portland on Wednesday. Excessive Heat Watches are in place from northern California into western Oregon and much of Washington in expectations of the heat wave to begin during the middle of the week, and likely peaking for the latter half of this week. Otto Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php