Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 353 AM EDT Thu Sep 27 2018 Valid 12Z Thu Sep 27 2018 - 12Z Sat Sep 29 2018 ...Heavy to excessive rainfall possible from the Tennessee Valley to the Mid-Atlantic today... ...Well below normal temperatures expected across the Central and Northern Plains... ...An elevated fire weather threat continues out west... A lingering frontal boundary draped from the Mid-Atlantic to the Western Gulf Coast will keep showers and thunderstorms in the forecast through at least Today. Locally heavy rainfall will be possible with excessive rainfall/flash flooding also a threat due to previous days of rain, especially across the Tennessee and lower Ohio Valleys. A wave developing along this boundary in the Mid-Atlantic on Thursday, moving up the coast on Friday, will also help to enhance rainfall from the Central/Southern Appalachians to southern New England. WPC has placed much of the region from the Tennessee Valley to the northern Mid-Atlantic within a slight risk for excessive rains/flash flooding today. Once this wave clears the Northeast on Friday, conditions should dry out just in time for the weekend. The southern portion of the front may linger a little longer, which keeps showery weather in the forecast into Saturday for portions of the Southeast and Gulf Coast. Another cold front dips in the northern tier states today, with scattered showers accompanying its passage across the Upper Great Lakes/Midwest to the Central Plains and northern Rockies. With cold Canadian air filtering in behind the front, expect some mixing of snow in the highest elevations with light accumulations possible. Temperatures across the northern High Plains on Thursday could be as much as 10 to 15 degrees below normal, with these cold readings dropping southward into the Central Plains by Friday. Meanwhile, upper level ridging holds strong across much of the Western U.S. into the weekend keeping the weather warm and dry. This will only continue an elevated fire weather threat, with Red Flag warnings and Fire Weather watches in effect across parts of the Great Basin and the Central Rockies. Expect compromised air quality as well given smoke from ongoing wild fires. Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php