Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 415 AM EDT Sat May 21 2016 Valid 12Z Sat May 21 2016 - 12Z Mon May 23 2016 ...There is a slight risk of severe thunderstorms over parts of the Northern High Plains and the Southern High Plains... ...Heavy rain possible along the Mid-Atlantic Coast and parts of the Northern Rockies... An upper-level low over the Ohio Valley will intensify as the low moves southeastward to the Southern Mid-Atlantic by Sunday evening. The system will produce rain over parts of the Lower Great Lakes into the Northern Mid-Atlantic on Saturday morning that will continue through Sunday evening. Rain will also move into parts of Southern New England by Saturday evening and into the Northeast on Sunday. In addition, showers and thunderstorms will develop over parts of the Southern Ohio Valley into the Southern Mid-Atlantic and the Southeast on Saturday morning that will move off most of the Southeast Coast by Sunday morning while continuing over parts of the Southern Mid-Atlantic through Sunday evening. Meanwhile, a much larger and deeper upper-level low over the West Coast will slowly move northeastward to the Northern High Plains by early Sunday while move just over the U. S./Canadian Boarder near the High Plains by Sunday evening. Rain and highest elevation snow will develop over parts of the Northwest and Northern California through Sunday evening. Showers and thunderstorms will develop over parts of the Northern Rockies into the Northern High Plains through Saturday evening the move eastward into the Northern Plains by Sunday morning continuing into Sunday evening. Additionally, showers and thunderstorm will develop over parts of Northern California into the Northern Rockies/Great Basin on Saturday with day time heating returning to rain overnight Saturday through Sunday evening. In the meantime, moisture from the Western Gulf of Mexico will stream northward over the Southern Plains on Saturday with a stronger flow of moisture on Sunday extending northward into the Central Plains. Showers and thunderstorms will develop over the Western Gulf Coast on Saturday expanding northward over the Southern Plains by Saturday evening and into the Central Plains on Sunday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php