Severe thunderstorms and heavy rain possible from the lower MississippiValley across the south-central Plains and through the upper Midwestthrough tonight......Growing Excessive Heat concerns over portions of California's centralvalley region as well as the Desert Southwest with Heat Risk persistingover southern Texas...Over the next couple of days, a shift in the weather pattern willgradually push the active weather that has been persisting over themid-section of the country toward the easte...