Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 354 AM EDT Fri Aug 28 2015 Valid 12Z Fri Aug 28 2015 - 12Z Sun Aug 30 2015 ...Heavy rain possible over parts of the Upper/Middle Mississippi Valley... ...Heavy rain possible over parts of the Pacific Northwest... Storm over the Middle Missouri Valley will slowly advance into the Upper Great Lakes by Saturday. The system will produce showers and thunderstorms from parts of the Southern High Plains northeastward to the Upper Great Lakes on Friday morning, waning to parts of the Middle Mississippi Valley by Friday evening and moving into parts of the Western Ohio Valley by Saturday evening. Rain will develop over parts of the Upper Mississippi Valley/Upper Great Lakes that will move into the Great Lakes by Saturday. Meanwhile, a front over the Eastern Pacific will move onshore over the Pacific Northwest on early Saturday moving inland to the Northern Intermountain Region/Northern High Plains by Saturday. The system will produce rain over the Pacific Northwest on Friday morning then tapering off by Friday evening. A second surge comes onshore overnight Friday producing more rain over the Pacific Northwest and parts of Northern California on Saturday. Additionally, some showers and thunderstorms will develop over parts of the Northern Intermountain Region/Northern Rockies by Saturday evening. Easterly flow off the Atlantic will stream moisture into the Southeast and develop showers and thunderstorms along an old boundary over the area through Saturday. In addition, monsoonal moisture and daytime heating will produce showers and thunderstorms over parts of the Southern/Central Rockies and the Southwest also through Saturday evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php