An extreme, prolonged heat wave from Texas to Louisiana is helping fuel deadly southern storms that have resulted in the deaths of at least six people and left hundreds of thousands without power.
State of play: A series of tornadoes hit Mississippi overnight, killing at least one person, wounding almost two dozen others and leaving over 49,000 without power, officials said. The severe weather also caused outages for nearly 187,000 people in Oklahoma, almost 79,000 others in Texas and some 69,000 in Louisiana as of Monday evening, per utility tracker poweroutage.us.
- An estimated 26,000 people in Arkansas also experienced outages, where a flash flood emergency was issued in the state's southwest:
Threat level: Some 30 million people were under excessive heat warnings, with millions of others under heat advisories, as the National Weather Service warned triple-digit temperatures would lead to critical fire weather conditions in parts of the Southwest in the coming days.
- This includes in New Mexico, where firefighters are already battling a large fire, and Arizona, where Phoenix on Sunday recorded its hottest temperature of the year so far — 109 degrees Fahrenheit.
- The NWS said Monday evening this "blistering" heat wave with excessive heat warnings and advisories would continue affecting Texas, Louisiana and the vicinity over the coming days.
"Meanwhile, strong to severe thunderstorms and heavy to excessive rainfall will be common the next few days in the Southeastern quadrant of the U.S. Gusty winds will impact parts of the West," the NWS added.
The big picture: The heat wave has triggered a series of storms across the southern U.S. since Thursday, when a tornado in Perryton in the Texas Panhandle killed three people.
- One person died during severe weather in Mississippi on Friday in Madison County, just over 30 miles north of Jackson, and another was killed during a suspected tornado event in Escambia County, Florida, Thursday.
- Louisiana Gov. John Bel Edwards declared a state of emergency for northern and central parts of the state on Saturday in response to the storm-related outages and in anticipation of more thunderstorms Sunday. The storm threat isn't over for the state.
Zoom in: A front over parts of Louisiana, Mississippi, Alabama, Georgia, and Florida "will create showers and severe thunderstorms over the area" and it could bring "frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes" through Tuesday, per the NWS.
- Central Texas was also at risk of severe thunderstorms.
Driving the news: The severe weather is due to a highly unusual summer setup with a branch of the jet stream screaming across the south, helping to trigger severe storms with large hail, strong straight-line winds and tornadoes.
- Typically the jet stream is located well north this time of year.
By the numbers: Heat indices have reached 120 degrees in Texas and Louisiana, and the heat index in Kingsville in the south of the Lone Star State hit 125°F on Thursday.
Of note: What's particularly unusual is the extent of 80°F dew points, leaving the air feeling extremely sultry. More humid heat can be tied in part to warmer-than-average waters in the Gulf of Mexico.
Context: Climate change is causing heat waves to be more intense, longer-lasting and more frequent.
- It's also resulting in more intense extreme precipitation events due to a warmer atmosphere that can hold more water vapor — providing added moisture and energy to storm systems.
Editor's note: This article has been updated with new details throughout.
