Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 AM EDT Fri May 10 2019 Valid 12Z Fri May 10 2019 - 12Z Sun May 12 2019 ...There is a slight risk of excessive rainfall with an embedded moderate over parts of the Southern Plains into the Lower Mississippi/Tennessee Valleys ... ...Heavy rain possible over parts of the Lower Mississippi/Tennessee Valleys... ...Temperatures will be 20 to 35 degrees below average for the Central/Southern High Plains... A slow moving front extending from the Lower Great Lakes southwestward to the Western Gulf Coast will move off the Northeast/Northern Mid-Atlantic Coast by Saturday morning. The southern half of the boundary will become quasi-stationary from the Southern Mid-Atlantic to the Western Gulf Coast/Lower Mississippi Valley through Sunday. Rain will develop a long and near the front from the Lower Great Lakes/Northeast southwestward to the Tennessee Valley that will move off the Northeast Coast by Saturday morning. On Friday afternoon, showers and thunderstorms will develop a long and ahead of the cold front over the Mid-Atlantic into the Tennessee Valley that will, likewise, move off the Mid-Atlantic coast by Saturday. A long the southern half of the boundary, showers and thunderstorms will develop over parts of the Lower Mississippi Valley/Western Gulf Coast and parts of the Southern Plains through Friday afternoon. A weakening upper-level impulse over the Lower Mississippi Valley will move into the Southeast by Saturday. The energy will aid in developing showers and thunderstorms over parts of the Southeast and Central/Southern Appalachians by Saturday. Overnight Saturday, the showers and thunderstorms will move into the Southeast/Mid-Atlantic and continue into Sunday. Additional upper-level impulses from Northwestern Mexico will move northeastward to the Middle Mississippi Valley by Saturday afternoon. Showers and thunderstorms will move out of the Southern High Plains over the Central/Southern Plains into the Middle/Lower Mississippi Valley by Saturday afternoon and into parts of the Ohio/Tennessee Valleys by Saturday evening into Sunday. Meanwhile, an upper-level low over California will slowly move into Northwestern Mexico by Sunday. The energy will trigger rain over parts of California into parts of the Southwest and into the Central/Southern Rockies, with some snow over the highest elevations of the Central Rockies through Saturday morning. Rain with daytime embedded thunderstorms will continue over parts of California into the Southern Rockies through Sunday. Another developing upper-level low over the Northern High Plains, overnight Friday, will move southeastward to parts of the Upper/Middle Mississippi Valley by Sunday. The energy will trigger rain over parts of the Northern Rockies/Northern High Plains that will expand into parts of the Northern Plains overnight Friday. The rain will move into parts of the Upper/Middle Mississippi Valley Saturday evening into Sunday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php