PHOENIX — The southwestern U.S. is about to feel the wrath of a punishing heat wave that includes a forecast of 120 degrees in Phoenix — a temperature not seen in the desert city in more than 20 years.
The broiling temperatures will also be felt in Las Vegas and Southern California, creating a public health hazard. Rising temps are being closely watched by everyone from airline pilots and emergency room doctors to power grid managers and mountain cities unaccustomed to heat waves.
Even cities accustomed to dealing with 110-degree days are grappling with the new problems that arise from 120 degrees.
Here is a look at five things related to the heat wave:
When the temperature soars, it's harder for airplanes to take off.
American Airlines pilot Shane Coffey said extreme heat creates changes in the air density that make it harder for airplanes to take off, meaning pilots have to use more thrust or impose weight restrictions such as flying with less cargo.
Air density on a 90-degree day in Denver at more than 5,000 feet elevation is similar to a 120-degree day in Phoenix at 1,100 feet above sea level, he said.
In 1990, amid a similar heat wave, flights were cancelled at the Phoenix airport because there was too much uncertainty about how the heat would affect aviation performance. Now, airlines have a better understanding, but the heat is still a concern — primarily for smaller, regional jets.
Airlines will be closely monitoring the heat this week and some flights could be affected.
The heat is a serious public health hazard in places such as Phoenix and Las Vegas where temperatures routinely exceed 110 degrees in the summer months.
The county that is home to Phoenix had 130 heat-related deaths in 2016, the highest number in more than a decade. It wasn't immediately clear what caused the uptick.
Kate Goodin, epidemiology and data services program manager at the Maricopa County Department of Public Health, said heat-related deaths span the entire Phoenix metro area, but underlying social and economic factors also have an impact.
Homeless people comprised one-third of heat-related deaths in 2016, according to county records. Most of the others involved people with non-functioning air conditioners.
"People who are economically disadvantaged have a harder time paying for increased electricity bills or keeping their water on throughout the entire year and those factors can predispose you to heat-related illness," Goodin said.