NEW : National Weather Service says 22 deaths may be due to tornadoes in Midwest . 141 million people are under watches or warnings , a spokesman said . Watches , warnings , and advisories cover more than 50 states .
NEW : National Weather Service says 22 deaths may be due to heat in Midwest . 141 million people are under advisories or warnings , NOAA spokesman tweets . Watches , warnings , and advisories cover more than 30 states .