Heavy rainfall and severe thunderstorm chances extend from the southernHigh Plains to the lower Mississippi Valley over the next few days......Wet and cool conditions forecast across the Great Lakes, Mid-Atlantic,and Northeast this weekend......Well above average temperatures expected throughout the West andnorth-central United States...After a brief lull, active weather is anticipated to return to thesouthern Plains tonight before spreading into the central/western GulfCoast and lower Missis...