Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 354 AM EDT Tue May 19 2015 Valid 12Z Tue May 19 2015 - 12Z Thu May 21 2015 ...Heavy precipitation is expected to return to portions of the central and southern Great Plains... ...Drier cooler conditions to extend from the northern Great Plains and upper Midwest through the Northeast and Mid-Atlantic states... ...Showers and thunderstorms to continue across portions of the Pacific Northwest, northern California and the Great Basin... Ongoing precipitation across portions of Colorado and New Mexico is expected to continue on Tuesday while spreading further to the north and east into Wyoming, Kansas, Nebraska and South Dakota. Mixed precipitation is expected across parts of the central Rockies and High Plains, with accumulating snows likely along the higher peaks. Rains falling across the lower elevations may become heavy as moisture streaming north from the Gulf of Mexico interacts with a well-defined upper level system moving across the western U.S. Heavy rain accumulations, which may produce localized flash flooding, are possible across the high plains of eastern Colorado into western Nebraska and Kansas. Further to south, showers and thunderstorms are expected to fire near a surface front stalled across the Texas Panhandle plains into the adjacent Red River area. Some of these storms may become severe with heavy rains and flash flooding possible. Across the West, unsettled conditions are expected to continue across the Pacific Northwest, northern California into the Sierra and the Great Basin, where showers and thunderstorms can be expected over the next two days. Showers and thunderstorms falling across the Northeast and Mid-Atlantic states early in the period, will be replaced by cooler and drier conditions by Wednesday as a well-defined cold front sweeps through the region. Behind the front, high pressure and below normal temperatures are expected to prevail across the Great Lakes region and upper Midwest into the middle part of the week. Pereira Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php