Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 349 AM EDT Tue May 22 2018 Valid 12Z Tue May 22 2018 - 12Z Thu May 24 2018 ...Moderate rain possible over parts of the Southeast/Eastern Gulf Coast... A front extending from the Mid-Atlantic westward to a surface low over the Great Lakes then southwestward to the Lower Mississippi Valley will move off the Northeast/Northern Mid-Atlantic Coast by Wednesday. The western half of the boundary will move southward to the Lower Mississippi Valley across the Southern Appalachians and parts of the Southern Mid-Atlantic by Wednesday evening. Showers and thunderstorms will develop along and near the front from the Mid-Atlantic to the Great Lakes then southwestward to the Lower Mississippi Valley that will move off the Northeast Coast by Wednesday evening. In addition, upper-level energy over the Southeast and Lower Mississippi Valley will aid in producing showers and thunderstorms that will expand westward by Tuesday afternoon into evening. The showers and thunderstorms will merge with the showers and thunderstorms along the aforementioned front over the Lower Mississippi Valley/Tennessee Valley that will continue through Wednesday evening. Meanwhile, an upper-level low over the Great Basin/Southern California will move northeastward and slowly weaken to the Northern High Plains by Wednesday evening. Moisture coming off the Western Gulf of Mexico will move northwestward into the Southern High Plains/Southern Rockies and interact with upper-level dynamics associated with the upper-level low producing showers and thunderstorms over the Southern High Plains through Wednesday evening. Underneath the deep upper-level trough associated with the upper-level low will trigger showers and thunderstorms over parts of the Northern High Plains into parts of the Great Basin on Tuesday morning. The showers and thunderstorms will expand into parts of the Northern/Central Rockies by Tuesday evening that will lift northward out of most of the Great Basin/Central Rockies by Wednesday evening. Overnight Tuesday into Wednesday, showers and thunderstorms will expand into parts of Northern California and parts of the Pacific Northwest. Additionally, a wave of low pressure over the Central High Plains will lift northwestward into the Northern High Plains by Wednesday evening. Showers and thunderstorms will develop along the associated front over parts of the Central Plains that will move northward into parts of the Northern Plains by Wednesday evening. In addition, showers and thunderstorms will also develop along the front over parts of Southern Plains/Lower Mississippi Valley by Tuesday afternoon, that will expand into parts of the Middle/Upper Mississippi Valley on Wednesday into Wednesday evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php