The sun shines down on pedestrians as they walk across the street in Salt Lake City on Tuesday, Sept. 6, 2022. (Scott G. Winterton/Deseret News)
SALT LAKE CITY — The ongoing September heat wave not only set records on the floor of the Salt Lake Valley, it created new temperature highs at altitude, according to the National Weather Service in Salt Lake City.
KSL meteorologist Matt Johnson says it’s still cooler at high altitude than it is in the valley — just not as much as we’d normally expect. So if you were hoping to escape the heat by driving uphill, you might find the relief is limited.
“In a standard atmosphere, pressure and temperature increase the lower in elevation you go,” Johnson said.
That’s one reason why Death Valley, at around 200 feet below sea level, is consistently one of the hottest places on Earth. But the high-pressure system sitting above northern Utah right now changes the game.
“The pressure and weight of the entire atmosphere stacked on top of the valley allows for efficient heating and hotting temperatures,” Johnson said. “Temperature is a direct measurement of energy: How fast are the particles moving and bouncing off each other?”
The faster they move, the hotter the temperature, and the higher the pressure, the higher the energy. On the flip side, Johnson said, pressure and temperature decrease the higher in elevation you go.
“This is true, but with this enormous high-pressure system on top of us, it is helping to create more energy at higher elevations. The air is more energized with faster-moving particles, with warmer temperatures even at the mountaintops,” he said.
In other words, it’s still cooler at higher elevations than it is in the valleys, but not as cool as you’d expect. The good news: relief may come soon.
“We’ll go triple digits today, tomorrow and on Thursday, but finally getting cooler air in here as this high pressure gets beat out by some lower pressure to the north,” Johnson said.
The relief remains relative; currently, the forecast high on Friday should still hit the 90s.