Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 343 AM EDT Sat Sep 13 2014 Valid 12Z Sat Sep 13 2014 - 12Z Mon Sep 15 2014 ...Temperatures will be 10 to 20 degrees below average from the Southern High Plains northeastward to the Great Lakes... ...Heavy rain possible over the southern tip of Texas... Cold high pressure over the Middle Mississippi Valley will move eastward to the Northern Appalachians by Sunday evening and modifying. A quasi-stationary front extending from the Southern Mid-Atlantic to the Gulf Coast will have waves of low pressure move along the boundary. One wave over the Carolinas will move northeastward to off the New Jersey Coast by Saturday evening then out over the Atlantic Ocean on Sunday. A second wave will develop over the Eastern Gulf Coast by Sunday evening. Showers and thunderstorms will develop along and near the front from the Mid-Atlantic to the Eastern Gulf Coast on Saturday. On Sunday, the showers and thunderstorms will develop over the Carolinas into the Eastern Gulf Coast. Additionally, along the western end of the front, easterly flow off the Western Gulf of Mexico and the lift provided by the boundary will aid in producing showers and thunderstorms over the Lower Rio Grande Valley through Sunday. In addition, rain will develop over parts of the Lower Rio Grande Valley through Sunday morning, too. Meanwhile, strong upper-level energy will aid in producing rain over parts of the Lower Great Lakes into parts of the Northern Appalachians on Saturday morning that will move eastward into Southeastern Canada and off Northern New England Coast overnight Saturday. Furthermore, upper-level energy and later easterly flow off the Atlantic will aid in producing showers and thunderstorms over the Southern tip of Florida through Sunday. Elsewhere, upper-level energy moving along the Northern Tier States will produce an area of rain over parts of the Northern Plains on Saturday afternoon moving into parts of the Upper Great Lakes by Sunday morning. The area of rain will expand into parts of the Middle Missouri Valley/Central Plains by Sunday evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php