Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 457 PM EDT Thu May 14 2015 Valid 00Z Fri May 15 2015 - 00Z Sun May 17 2015 ***Moderating temperatures for the eastern U.S.*** ***Concerns for flash flooding and severe weather return to the Plains*** ***Much colder, wet and unsettled weather expected over the western U.S.*** High pressure along the East Coast which has helped to bring notably cooler and drier weather to the Ohio Valley, Northeast and Mid-Atlantic over the last couple of days will move offshore on Friday. This will allow for a warming trend this weekend as very warm and more humid conditions across the Mississippi Valley and Gulf Coast states advances northeast. This will also allow for an area of low pressure and an associated area of showers and thunderstorms over the Midwest to move east across portions of the Great Lakes region and gradually into the Ohio Valley and portions of the Northeast this weekend. For the western U.S., a deep and pronounced upper-level trough will migrate across the West Coast and become situated over the Intermountain West through the weekend. Much cooler temperatures, along with widespread showers and thunderstorms can be expected, which will bring some much needed rain and high elevation snowfall to some of the drought-stricken areas of California and the Great Basin, including the Rockies. The energy will traverse the Four Corners region and should invigorate a robust area of low pressure out across the High Plains. This will help drive a very warm and humid air mass north through the Plains for Friday and into the weekend, and set the stage for additional rounds of heavy showers and thunderstorms. This will impact areas that have already seen locally significant rains, flash flooding and severe weather over the last couple of weeks. It is expected that additional flash flooding and severe weather will materialize for especially the central and southern Plains over the next couple of days as this next storm system advances through the West and into the Central U.S. over the next couple of days. Orrison Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php