Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 433 PM EDT Sun Jun 11 2017 Valid 00Z Mon Jun 12 2017 - 00Z Wed Jun 14 2017 ...There is a slight risk of severe thunderstorms over parts of the Upper Great Lakes and parts of the Central High Plains... ...Heavy rain possible over parts of the Upper Mississippi Valley/Northern High Plains/Northern Rockies and Great Basin... ...Temperatures will be 10 to 25 degrees below average over parts of the Great Basin/Pacific Northwest/California and the Southwest... ...Snow possible at highest elevations of the Sierras/Great Basin/Northern Rockies... A front extending from Southeastern Canada to the Great Lakes southwestward to the Central High Plains will unit with a reinforcing front moving southward out of Central Canada by Monday afternoon. The boundary will extend from the Northeast across the Great Lakes into the Northern Plains by Tuesday. Showers and thunderstorms will develop along and ahead of the front over the Upper Great Lakes into the Upper Mississippi Valley/Middle Missouri Valley. Overnight Sunday, the showers and thunderstorms will extend southwestward along the boundary into the Central Plains. Overnight Monday, the showers and thunderstorms will lift northward to the Northern Plains to the Great Lakes. In addition, showers and thunderstorms will develop over parts of Northern Maine that will move southward and extend from New England Coast westward to the Lower Great Lakes by Tuesday. Meanwhile, an upper-level low over California will move northeastward to the Northern High Plains/Northern Rockies by Tuesday. The system will produce rain with some embedded thunderstorms from parts of the Pacific Northwest/Northern California into parts of the Northern/Central Rockies and the Great Basin that will expand into parts of the Northern Plains Monday into Tuesday. Snow will develop over some of the highest elevations of the Sierras into the Great Basin overnight Sunday moving into parts of the Northern Rockies by Monday evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php