Temperature 'arena' captures most of the US in Pressure Cooker

For many hundred thousands of people continuing this week's severe temperature and humidity, it suffers like they're residing in a pressure cooker. And in a sense, they are.

Much of the United States is fascinated under a heat "arena" caused by a massive area of high pressure that's condensing hot, moist air beneath it, leading to depressed temperatures in the mid-90s to low 100s and heat-index levels well above 100 degrees. The harsh conditions enhanced from the northern Plains states to Texas and from Nebraska to the Ohio Valley. And they're increasing eastward.

"It's hot no matter what you're doing or where you are," said Tim Prader, a 50-year-old construction employee who was taking a break Tuesday at a job site in St. Louis. Though his greater Caterpillar excavator has air conditioning, he couldn't totally run away. "When you're ended for the day, you're ready to eat, drink and hit the couch."

When a lofty pressure system builds up in the upper atmosphere, the air below it goes down and compresses because there's more weight on top, causing hotness in the lower atmosphere to heat up, said Eli Jacks, a meteorologist with the National Weather Service in Silver Spring, Md.

The arena of higher pressure also drives the jet stream and its drier, cooler air, farther north — it's now glowing into Canada — while hot, moisture air from the Gulf of Mexico circulates clockwise around the dome, traveling beyond inland than normal. Collective with ordinary clear skies and the sun's higher summertime angle, "it gets really hot," Jacks said.

That also describes why heat in, say, North Dakota this week aren't all that dissimilar from temperatures in Houston, he said. The huge difference is that people in Houston are familiarized to hot weather, while those in the north are not.

"In sites where the higher heat you ever expect is in the 80s and you're at 102, there are largest health concerns," because some people have air conditioning or fans, Jacks said. "Hot weather is the No. 1 killer out of all weather difficulties."

What's more, because of the moisture, even nighttime brings little break.

"It's been 100 degrees at 11 o'clock, lately, at night," said Curtis Mark, who was overhauling air conditioners Tuesday at the Greer County Courthouse in Mangum, Okla., where the heat was 106 degrees at noon. "Stay indoors is about all I do."

Fellow Oklahoman Norma Lauer of Granite said she places cold water on her hands and arms before going to sleep and then lies down "without covering up on the bed, under the fan" and with the air conditioner operating.

Downpours can create around the perimeter of the arena — called the "ring of fire" — bringing momentary break to some parts, said Kevin Birk, a National Weather Service meteorologist in Illinois. But this arena is so huge that the heat re-creates rapidly, Birk said.

As heat domes aren't rare, this one is strange because of its size and time. It started three days ago and may last seven to 10 days in some areas. And it's moving eastward, with heats expected to touch 100 degrees in Washington by Thursday.

National Oceanic and Atmospheric Administration records appear that the United States broke 25 local toper records for the date on Monday, including 103 degrees in both Edgemont S.D., and Victoria, Texas.

On Tuesday, it was 102 in Manhattan, Kan., and Valentine, Neb. The mercury rose to 100 in Joplin, Mo., and Rockford, Ill. — which attach that city's record for the date set in 1930. And in some cities it will be even hottest Wednesday: Chicago reached 93 degrees Tuesday, with 97 forecast for Wednesday.

But break is on the way. Cooler air should start moving into the Plains states this weekend, as a strong pool of air from the jet stream starts to push hot air out of the way in the Dakotas and into Minnesota before making its way east. By Monday, heats will fall into the mid-80s in the north, as they still could be boiling in the East, he said.

"This is in fact an outstanding event, I think it's honest to say ... in terms of scope and period," he said.

Sweet corn farmer Ron Deardorff of Adel, Iowa, is ready for a relief in the weather.

The 64-year-old spent Tuesday morning assisting his crew of 24 pick corn in the field and by noon was driving the harvest to a grocery store in Des Moines — with a heat of 95 degrees, a temperature guide of 105 and no air conditioning.

"A short time I have to change shirts in the mid of the day or middle of the afternoon and obtain a dry one, " said Deardoff, who kept his truck expels wide open and the windows rolled down. "It's no fun and no one likes it, but the season is only so lengthy and when the corn's ready, it's ready. You only have to go after it and do what you've got to do."