Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 349 AM EDT Tue Sep 15 2015 Valid 12Z Tue Sep 15 2015 - 12Z Thu Sep 17 2015 ...Temperatures will be 10 to 20 degrees above average from the Plains into parts of the Upper Great Lakes... A quasi-stationary front extending from the Upper Mississippi Valley to parts of the Great Basin will have a wave of low pressure over the Northern Plains that will move northward into South-Central Canada by Wednesday evening. A second wave of low pressure over the Northern Rockies will move to the Northern High Plains by Wednesday evening, too. The associated upper-level energy will aid in producing showers and thunderstorms over parts of the Great Basin to the Central Rockies through Wednesday. In addition, an area of showers and thunderstorms will develop over parts of the Central Plains into the Upper Great Lakes/Upper Mississippi Valley late Tuesday night into Wednesday morning. Also, showers and thunderstorms will develop over the Northern High Plains to parts of the Upper Great Lakes by Wednesday evening. Furthermore, rain will develop over parts of the Northern Intermountain Region/Northern Rockies into parts of the Northern High Plains through Wednesday. Additionally, onshore flow on Tuesday followed by additional upper-level energy moving onshore over the Pacific Northwest/Northern California, on Wednesday, will produce rain along the Northwest/Northern California Coast through Wednesday evening. Elsewhere, in general high pressure will dominate the area east of the Mississippi River on Tuesday and Wednesday. While return flow off the Western Gulf of Mexico and upper-level energy will aid in producing showers and thunderstorms from the Western Gulf Coast to the Southeast Coast through Wednesday evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php