Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 406 PM EDT Mon Sep 08 2014 Valid 00Z Tue Sep 09 2014 - 00Z Thu Sep 11 2014 ...There is a slight risk of severe thunderstorms over parts of the Middle/Lower Missouri Valley... ...Heavy rain possible from parts of the Upper Great Lakes to the Middle Mississippi Valley... ...Heavy rain possible from parts of the Mid-Atlantic and Southeast Coast as well as over parts of Central Rockies... ...Temperatures will be 10 to 20 degrees below average over parts of the Northern High Plains/Northern Rockies... A front extending from the Upper Mississippi Valley to the Northern Rockies will move southward to the Central Plains and eastward to the Upper Great Lakes. Additionally, a wave of low pressure along the boundary will deepen significantly as the low moves from the Northern Plains to Eastern Iowa by Wednesday morning. Cold air behind the front will aid in the development of snow over parts of the Northern Rockies/Northern High Plains from early Tuesday morning through Wednesday. In addition, upslope flow associated with high pressure over Western Canada will aid in producing the snow and rain over parts of the Northern High Plains/Northern Rockies and expand into the Northern Plains Tuesday night into Wednesday. Moisture rich air from the Gulf of Mexico will move northward over the Plains to the Middle Mississippi Valley by Wednesday. The moisture and the developing low over the Northern Plains will aid in producing showers and thunderstorms with moderate rain over parts of the Middle/Upper Mississippi Valley by Tuesday evening expanding into parts of the Great Lakes by Wednesday morning. Upper-level energy over the Central Plains will move to the Ohio Valley by Tuesday evening. The energy will trigger showers and thunderstorms over parts of the Middle Mississippi Valley Monday into Tuesday afternoon. Furthermore, monsoonal moisture will also aid in producing showers and thunderstorms over parts of the Southwest/Southern California into parts of the Great Basin and the Central/Southern Rockies that will slowly wane to small parts of the Southwest/Central Rockies by Wednesday. Meanwhile, low pressure moving along a stationary front along the Southeast Coast will produce showers and thunderstorms with moderate rain over parts of the Southeast/Mid-Atlantic Coast through Tuesday evening. Showers and thunderstorms will also develop over parts of the Central/Eastern Gulf Coast waning to Florida by Wednesday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php