Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 259 PM EDT Fri Sep 18 2015 Valid 00Z Sat Sep 19 2015 - 00Z Mon Sep 21 2015 ...There is a slight risk of severe thunderstorms through Saturday morning across portions of the southern/central plains and Midwest... ...Flash flooding is possible for portions of the Midwest through Saturday morning... A robust upper-level disturbance provided enough strength to send the expansive cold front across the central portions of the CONUS today. A vast area of showers and thunderstorms have developed along and ahead of the front throughout the day. The Storm Prediction Center has highlighted an area spanning from Oklahoma to Illinois as having a slight risk for storms to turn severe. Please refer to products issued by SPC for further details on the severe weather threat. This same area also has the potential for flash flooding as higher rainfall amounts and intensities focus over this already saturated region. On Saturday, the cold front will move through the Lower Great Lakes and the Appalachians reaching the Northeast/Mid-Atlantic coastline by Sunday morning. Showers and thunderstorms will persist ahead of the front. A much cooler airmass will settle in behind the front as high pressure builds. Fall-like temperatures are forecast for much of central and eastern U.S. The frontal boundary will stall across the southern plains Saturday night and will eventually begin to move north as a warm front. Thus, showers and thunderstorms will remain a possibility across the southern plains into Sunday. Another system will begin moving through Canada and the Pacific Northwest toward the end of the weekend. Thus, showers will be possible for coastal areas of Washington and British Columbia. Portions of Mexico and the Desert Southwest will see a slow and steady influx of tropical moisture that is fairly uncommon for this late in the season. Showers and thunderstorm that develop over this region will yield much higher rain fall amounts. Three day totals for the region may range from 0.25 to 2.00 inches, with nearly 4.75 inches possible over the Baja peninsula and the Sea of Cortez. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php