Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 426 PM EDT Sun May 14 2017 Valid 00Z Mon May 15 2017 - 00Z Wed May 17 2017 ...Heavy precipitation possible over parts of the Cascades... ...Heavy rain possible over parts of the Upper Great Lakes... Deep upper-level trough over the West Coast will slowly move inland to the Northern Rockies southward to the Southwest by Tuesday. The system will produce rain and higher elevation snow over parts of the Pacific Northwest/Northern California into parts of the Northern Rockies that will temporarily end over most places by Monday morning. Weak onshore flow over parts of the Northwest will stop overnight Sunday. A new round of onshore flow will move into the Pacific Northwest by Monday evening continuing into Tuesday. The increase of moisture will aid in developing additional rain and higher elevation snow over parts of the Pacific Northwest and the Northern Rockies on Monday afternoon into evening. On Monday evening, rain will develop over parts of California and into the Great Basin. The rain will mainly stop over California and the Great Basin by Tuesday. The rain will increase in intensity over the Northwest overnight Monday into Tuesday. Meanwhile, disorganized upper-level energy will stream out from the upper-level trough moving eastward into the Upper Great Lakes by Tuesday. The energy will aid in producing showers and thunderstorms over parts of the Northern Plains/Upper Mississippi Valley that will move into the Upper Great Lakes by Monday morning. Overnight Sunday as more upper-level energy moves out of the deep trough over the West Coast, showers and thunderstorms will develop over part of the Northern High Plains into the Northern Plains that will expand eastward into the Upper Mississippi Valley/Upper Great Lakes by Monday afternoon that will continue into Tuesday. In addition, showers and thunderstorms will develop over parts of the Southern/Central High Plains overnight Monday into Tuesday. Elsewhere, an upper-level low over the Great Lakes/Northeast will slowly move off the Northeast Coast and move to the Canadian Maritimes by Tuesday. Rain will develop over the Northeast that will slowly diminish to a small area over Northern Maine by Tuesday morning. Additionally, upper-level energy over the Florida Peninsula will aid in producing showers and thunderstorms over parts of the southern tip of Florida through Tuesday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php