Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 341 AM EDT Sat Aug 18 2018 Valid 12Z Sat Aug 18 2018 - 12Z Mon Aug 20 2018 ...Active weather continues for the East Coast... ...Heavy rainfall expected to impact parts of the Plains and Mississippi Valley this weekend... ...Air quality will remain a concern this weekend across much of the Northwestern U.S. and also parts of the Upper Mississippi Valley... A cold front stretching from New England to the southern Plains will be the focus for showers and thunderstorms throughout the south and east this weekend. As the cold front presses eastward across the Northeast, Mid-Atlantic and Tennessee Valley, convection will fire along and ahead of the boundary. Scattered to numerous thunderstorms will impact these regions in addition to the Southeast. As the front stalls along the Mid-Atlantic and Tennessee Valley on Sunday, this will give way to more rounds of showers and thunderstorms. Some of these storms could produce heavy downpours that may lead to flash flooding. In the southern Plains, the front draped across Texas that is associated with the cold front in the east will lift as a warm front by this afternoon. Thunderstorms are expected along the boundary especially across the Red River Valley. In addition, thunderstorms are also expected in the High Plains along the lee trough--with a marginal risk of severe weather possible with this activity. By tonight, a surface low accompanying this warm front will lift north and east from the Plains to the Mississippi Valley. Heavy rain is expected near this low, and will move from the southern/central Plains on Sunday into the middle Mississippi Valley by Monday. A slight risk of flash flooding is possible along with a marginal risk of severe weather. Fire weather in the Intermountain West and parts of the Great Basin remain elevated today. Red flag warnings are in effect for parts of Idaho, western Montana, and a small portion of Utah. Furthermore, air quality from these fires remain an issue across parts of California, the Pacific Northwest, in addition to the Upper Midwest--with these regions having air quality alerts in effect. Reinhart Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php