Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 357 AM EDT Wed May 17 2017 Valid 12Z Wed May 17 2017 - 12Z Fri May 19 2017 ...Heavy rainfall and severe thunderstorms possible from the Southern Plains to the Upper Midwest through Thursday... ...Wet and cool conditions are expected across the Western U.S. with late season snow in the higher terrain... ...Above normal temperatures expected across much of the Eastern U.S. this week... A frontal boundary, spanning from the Southern Rockies/Southern Plains to the Great Lakes region, will slowly track eastward over the next few days. Scattered to numerous showers and thunderstorms will fire up along and ahead of this boundary, keeping much of the central in an active, wet pattern. Some of these storms will have the potential to turn severe and contain heavy rainfall capable of producing flash flooding. The Storm Prediction Center is highlighting a slight to enhanced risk of severe weather across much of the Upper Midwest/Upper Mississippi Valley today...with slight to moderate risk on Thursday across the Southern and Central Plains. WPC has highlighted a marginal to slight risk for flash flooding across the same areas. Much of the East can expected mostly dry and above normal temperatures under the upper-level ridge. Many locations across the Ohio Valley, the Mid-Atlantic, and the Northeast may observe afternoon temperatures ranging 10 to 20 degrees above normal this week. Rain and high elevation snows are forecast across much of the Northwest, Great Basin, and northern and central Rockies as an upper-level low drops through the region. Several inches of snow, possibly up to a foot, will be possible across the mountains with winter storm warnings, watches, and winter weather advisories in effect. Once the upper low reaches the central Rockies on Thursday, the threat for severe thunderstorms and heavy rainfall will return for portions of the Southern Plains. Temperatures across the West will also be well below normal with afternoon highs as much as 10 to 25 degrees below normal. Campbell/Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php