Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 255 AM EDT Sat Apr 18 2015 Valid 12Z Sat Apr 18 2015 - 12Z Mon Apr 20 2015 ...Episodes of severe weather including flash flooding will be possible this weekend from the central and southern plains into and across the lower-middle Mississippi valley... ...Lingering snow showers over the central Rockies to end tonight.. A strong spring storm system over the central Rockies will be partially responsible for an active weekend of weather across the central and southern part of the lower 48. A favorable combination of deep moisture from the Gulf of Mexico, instability and wind shear are expected to be in place out ahead of a mid-level cyclone currently over the central Rockies. The potential for tornadoes, large hail, strong winds and flash flooding will be in place at times throughout the weekend out ahead of an advancing cold front. Temperatures directly beneath this storm system are cold enough to support higher elevation snow across Colorado and Wyoming, but as the storm system departs into the Great Plains tonight, snow showers will come to an end. The greatest threat for flash flooding will be today and tonight from the upper Texas coast to the Florida panhandle, where recent heavy rains have made for saturated soils which will again see a threat for excessive rainfall rates. Regarding temperatures, highs today will be well into the 70s with a few pockets of lower 80s from the Midwest to the Mid-Atlantic states, but much cooler weather is expected here for Sunday along with some rain. Temperatures will fall to 5 to 15 degrees below average across the central U.S. in the wake of the cold front referenced above. The western U.S. will continue to see mild temperatures of 10 to 15 degrees above average under fair skies and upper level ridging aloft. Otto Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php