Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 354 AM EDT Tue Jul 21 2015 Valid 12Z Tue Jul 21 2015 - 12Z Thu Jul 23 2015 ...Heavy rain possible over parts of the Southern Plains... A front extending from the Lower Great Lakes to the Southern Plains will move eastward off the Northeast/Mid-Atlantic Coast by Wednesday morning while the trailing portion of the boundary stretches westward from the Carolina Coast to the Southern Plains. Showers and thunderstorms will develop along and ahead of the front from the Lower Great Lakes/Northeast to the Tennessee Valley westward to the Southern Plains that will move off the Northeast/Mid-Atlantic Coast by later Tuesday night. In addition, showers and thunderstorms extends westward from the Southeast Coast to the Southern Plains through Wednesday evening. Furthermore, moisture pooling over the Southeast will aid in triggering showers and thunderstorms through Wednesday. Meanwhile, a front over the Pacific Northwest will slowly move eastward to the Northern High Plains/Great Basin by Wednesday. Showers and thunderstorms will develop along the warm front over the Northern High Plains and advance eastward to parts of the Northern/Central Plains by Tuesday evening then fade over the Upper Mississippi Valley by Wednesday evening. On Wednesday, showers and thunderstorms will develop along the front over parts of the Northern Intermountain Region during the morning that will expand into parts of the Great Basin and the Northern High Plains by Wednesday evening. Additionally, moisture over California will trigger showers and thunderstorms over parts of Southern/Central California into parts of the Great Basin through late Tuesday night. Monsoonal moisture and diurnal heating will produce showers and thunderstorms over part of the Southern/Central Rockies through Wednesday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php