Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 409 PM EDT Fri May 17 2019 Valid 00Z Sat May 18 2019 - 00Z Mon May 20 2019 ...Severe thunderstorms likely for the Plains states west of lower and mid-Mississippi Valley during the weekend... ...Heavy rain and some flash flooding will be possible across portions of the Great Plains and Midwest... ...Much cooler than normal temperatures will continue for much of the western U.S. and the northern Plains... A series of cold and energetic upper-level troughs will continue to bring active weather from the northeastern Pacific into the western U.S. This will allow unsettled weather and very chilly temperatures to continue for much of the West and into the northern Plains. In fact, the higher elevations of the Intermountain West and the northern Rockies will be cold enough to see accumulating snow, while valley locations will see a chilly rain. Areas in the northern High Plains could even see rain changing to wet snow before tapering off Saturday night. High temperatures in some locations will be as much as 20 to 30 degrees below normal for Friday and Saturday, and this very cool and unsettled pattern should last generally through the weekend across the West. Meanwhile, energy ejecting from the lead upper-level trough is currently edging its way into the Great Plains. This will trigger the formation of a couple of low pressure waves moving across the central Plains along a front, setting the stage for fairly widespread heavy showers and thunderstorms to move generally eastward across the Plains toward the Mississippi Valley during the weekend. The Storm Prediction Center has highlighted a fairly large area of Slight to Enhanced Risk of severe weather mainly west of the Mississippi Valley for the weekend. In addition, heavy rainfall will likely result in flash flooding issues in these areas and further north into the upper Midwest. Meanwhile, the next system from the Pacific will begin to move onshore and bring another round of widespread precipitation across the western U.S. On the other hand, some heat and humidity is forecast to spread eastward from the central and southern Plains toward the East Coast through the weekend. It appears that the marine air will keep New England and coastal Mid-Atlantic cool for the weekend. However, afternoon temperatures could reach the low 90's on Sunday over parts of the Ohio Valley, interior Mid-Atlantic, and the interior Southeast. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php