Explaining why it’s so miserably hot – Orange County Register

Blacktops, freeways, the urban mall.

Global warming, too, but that’s not all.

“And Mother Nature with this stationary high-pressure system,” adds Bill Patzert, climatologist at NASA’s Jet Propulsion Laboratory in Pasadena, explaining why it’s going to continue to be unreasonably hot for several more days.

“It’s called the triple heat whammy,” he said.

Patzert on Monday, June 19, called upon his 34 years of research at JPL to boil down the science behind the extreme heat – what can’t be seen but can be measured.

How extreme? As a high-pressure system anchored over Arizona strengthens, highs in the Inland valleys — parts of Riverside and San Bernardino counties south and west of the mountains — were expected to hit 103 to 111 on Tuesday and Wednesday, according to the National Weather Service.

Things will be a few degrees hotter in the High Desert north of the San Bernardino Mountains, and hotter still in the San Gorgonio Pass and Coachella Valley, where temperatures could reach into the high 110s to low 120s.

“It’s a bit of a shock because May gray and June gloom were on schedule,” Patzert said. “It was a nice (cool) end of the spring and start of summer, but we got whiplashed by this high-pressure system.”

A sinking feeling

These high, long-lasting temperatures are linked with the jet stream, which comes out of the Pacific Ocean and controls the weather in the United States, Patzert said.

When the jet stream shifts north into the Pacific Northwest and Canada, it tends to pull up warm air from the south, such as the Mexican desert.

The high pressure pushes air toward the ground, in contrast with a low-pressure system that sucks the air off the surface. When the air sinks, it compresses, or gets squeezed, and the temperature rises.

When the heated air hits the ground, it spreads.

“I call it a crushing dome of high pressure in the upper atmosphere,” Patzert said.

And here’s one of the reasons why the National Weather…

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