Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 354 PM EDT Sun May 28 2017 Valid 00Z Mon May 29 2017 - 00Z Wed May 31 2017 ...A lingering upper-level low will keep cool and showery conditions from the northern Plains eastward to New England... ...Scattered showers and thunderstorms continue along the East Coast as well as over the Deep South where heavy downpours are possible... ...Hot conditions expected for the interior Pacific Northwest and the Desert Southwest... A large upper-level low is forecast to deepen and move slowly eastward across the Great Lakes over the next couple days. This will keep temperatures below normal from much of the Great Plains eastward across the Mississippi Valley, the Great Lakes, and into New England. The large cyclonic circulation will rotate small-scale disturbances into the northern U.S., resulting in occasional showers and isolated thunderstorms, especially during the afternoon and early evening hours through Tuesday. Meanwhile, the main front associated with this system should gradually push eastward into the Eastern Seaboard on Memorial Day and becomes nearly stationary across the mid-Atlantic on Tuesday. This will keep a good chance of showers and thunderstorms up and down the East Coast through Tuesday. The truly warm and humid air will remain south of the front over the Southeast and across the Deep South through Tuesday, where clusters of thunderstorms can be expected. Some of these thunderstorms could be heavy enough to result in flash flooding just inland from the western Gulf Coast through tonight. Meanwhile, a high pressure system similar to one in the cold seasons is forecast to build southward from western Canada into the northern High Plains. This will send another batch of cool Canadian air into the area during the next couple of days. In contrast, a brief heat wave is forecast for the interior Pacific Northwest through Tuesday as high temperatures are expected to reach low to mid 90's over the Snake River Valley. Meanwhile, triple-digit heat is expected for the Desert Southwest due to the influence of an upper-level ridge. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php