Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Sat May 27 2017 Valid 00Z Sun May 28 2017 - 00Z Tue May 30 2017 ...Showers and thunderstorms will gradually shift from the mid-section of the country to the East Coast and the Deep South through Memorial Day... ...Very warm weather expected to develop over the Pacific Northwest while cool weather persists from the Great Plains eastward to New England... This Memorial Day weekend will feature a broad upper-level trough dominating much of the eastern two-thirds of the country. This will result in cooler than normal temperatures from the Plains eastward to New England through Memorial Day. The leading edge of the cool air will slowly edge towards the south and east. Showers and thunderstorms associated with the frontal boundary will gradually shift from the central U.S. this afternoon and evening, and spread into the Deep South and much of the East Coast by Memorial Day. The front is expected to become stationary across the mid-Atlantic. This will keep the warm and humid air over the Southeast while overcast and cool weather persists from the mid-Atlantic northward. As a low pressure center develops and heads towards the Great Lakes, showers and thunderstorms will spread across the Ohio Valley on Sunday before reaching the mid-Atlantic, followed by New England on Memorial Day. Meanwhile, showers and thunderstorms near the tail end of the front could be heavy enough to lead to flash flooding over southern Texas on Memorial Day. A lingering broad upper-level low centered north of the Great Lakes will continue to send periodic intrusions of cool air from central Canada down into the Plains, keeping temperatures there cooler than normal through Memorial Day. In contrast, warm and dry conditions are expected to develop over the Pacific Northwest. High temperatures are forecast to reach the lower 90s on Sunday, which are 10 to 20 degrees above average. The warm weather is expected to spread farther south and east into the Great Basin on Memorial Day. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php