Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 436 PM EDT Tue May 19 2015 Valid 00Z Wed May 20 2015 - 00Z Fri May 22 2015 ...Flash flooding and severe thunderstorms possible across portions of the central U.S... ...Below average temperatures expected across portions of the plains and Midwest... The weather pattern will remain active across portions of the central U.S. over the next couple days. A persistent surface frontal boundary remains in place across the southern plains, with widespread showers and thunderstorms north of the front.. A wave of low pressure is forecast to develop along the front across the southern/central plains on Wednesday. An area of widespread rain and thunderstorms will move eastward north of the surface low into the Middle Mississippi valley on Wednesday. South of the frontal boundary, a dry line will serve as a focus for the development of showers and thunderstorms through Thursday. The Storm Prediction Center is forecasting a slight risk of severe thunderstorms across portions of the southern plains through Wednesday. Please refer to products issued by the SPC for further details on the severe weather threat. Flash flooding will also be possible across the southern plains as heavy rain from thunderstorms will fall on previously saturated ground. Wednesday night into Thursday, the front will move south across Texas as a cold front, with the potential for widespread shower and thunderstorms activity along and north of the front. North of the front, Canadian high pressure will build into the central/northern plains , with below average temperatures expected. Snow may even mix with rain across portions of the central/northern High Plains early Wednesday morning before precipitation comes to an end. Another wave of low pressure is forecast to develop along the frontal boundary across the Southeast on Thursday, which will bring scattered showers and thunderstorms to portions of the Southeast and Mid-Atlantic. Across the West, a broad upper-level trough and a lingering surface front will keep conditions unsettled over the next couple days, with scattered showers and thunderstorms along with high elevation snow showers across much of the Intermountain West. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php