Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 349 AM EDT Sat May 02 2015 Valid 12Z Sat May 02 2015 - 12Z Mon May 04 2015 ...Showers and thunderstorms with locally heavy rainfall possible across the Upper Midwest on Sunday... ...Temperatures will be above average across much of the nation... A relatively quiet weather pattern will be in place across the contiguous U.S. through the weekend. Upper-level flow across the country will be zonal and the most significant upper-level disturbances will move along the U.S./Canada border. A cold front associated with one of these disturbances will cross the northern Intermountain West today and reach the northern plains by tonight. As the front approaches the Upper Midwest late tonight into early Sunday morning, and taps into a better inflow of moisture and instability, a more widespread area of showers and thunderstorms is forecast to develop. Locally heavy rainfall is possible in association with these showers and thunderstorms. Across the West, scattered showers and thunderstorms, mainly during the afternoon and evening, will be common. A cold front will sag southward toward the Great Basin today and will become stationary tonight into Sunday. This boundary will serve as a focus for showers and thunderstorms. Elsewhere across the west, including the central Rockies and Four Corners region, scattered showers and thunderstorms will be driven primarily by terrain and very weak upper-level impulses traversing these areas. Showers and thunderstorms may become more widespread across the eastern slopes of the Rockies in portions of Colorado and Wyoming late Sunday as the cold front approaches and surface winds turn more easterly with an upslope component. Temperatures will be above average through Sunday across much of the nation, with the exception for the Southeast, lower Mississippi valley, and Gulf Coast. Across the northern plains and Upper Midwest, temperatures will be 15 to 20 degrees above average, with high temperatures today and Sunday reaching well into the 80s in many areas. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php