Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 426 PM EDT Sun Aug 24 2014 Valid 00Z Mon Aug 25 2014 - 00Z Wed Aug 27 2014 ...There is a slight risk of severe thunderstorms over parts of the Upper Mississippi Valley... ...Temperatures will be 10 to 20 degrees below average over parts of the Northern High Plains... A broad storm system over the Upper Missouri Valley will slowly move eastward through the Northern Plains and Upper Midwest during the next 24 to 48 hours. Chilly air, well-below normal temperatures and widespread steady rains will migrate across Montana tonight and into North Dakota on Monday. The cold front is expected to spread into South Dakota, Minnesota, Nebraska, Kansas and the upper Great Lakes later tonight and during the day on Monday---with showers and thunderstorms along the front. Tonight, some of these thunderstorms may become severe in Minnesota---with large hail and isolated tornadoes---the primary severe weather threats. A series of weak upper-air disturbance over the lower Mississippi Valley and Gulf Coast will generate scattered showers and thunderstorms across the South and Gulf Coast tonight, and spread westward into the far western Gulf coast and south Texas early Monday. This disturbance should bring---at the very least---scattered cloudiness and some brief relief to the excessive heat and humidity prevailing across the region---where upper 90s and triple-digit heat indices have been the norm all weekend. These weak disturbances will continue to produce isolated showers and thunderstorms across the southern states into Monday evening and Tuesday morning. In the East, cool and dry weather will prevail during the next 24 to 36 hours---with high pressure remaining anchored along and east of the Appalachians from the Piedmont northward into the Berkshires. Coastal interests should continue to follow the National Hurricane Center for the latest forecasts concerning Tropical Storm Cristobal in the Atlantic and Hurricane Marie in the Pacific. Vojtesak Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php