PHOENIX (AP) -- Tigers at the Phoenix Zoo are getting frozen fish snacks. Temporary cooling stations are popping up to welcome the homeless and elderly. And airlines are monitoring the soaring temperatures to make sure it's safe to fly as the western U.S. falls into the grip of a dangerous heat wave.
A strong high-pressure system settling over the region Friday and through the weekend will bring extreme temperatures to the already blazing Southwest. Notoriously hot Death Valley, Calif., is forecast to reach 129 degrees, not far off its world-record high of 134 logged nearly a century ago.
"We came to this special place to experience it at its best," said Hermenn Muessner with a smile. Muessner, from the Alpine country of Lichtenstein, planned to continue his tour through the Southwest with a stop at Yosemite National Park, where temperatures were expected in the high-80s.
By 9:30 a.m., the temperature had already climbed to 110 in the shade outside a pro shop at a Death Valley golf course. Tourists appeared to move in slow motion in the intense heat. They took photos of the landscape or of themselves in front of national park signs, and then got back into their air-conditioned cars.
When he arrived the night before, Juergen Bausch saw that the car's thermometer said the temperature outside was at 118. He took a photo of the reading and sent it to his friends back home in Germany. And then he got out of the car.
"Wow what a surprise," he said.
The National Weather Service predicts Phoenix could reach 118 on Friday, while Las Vegas could see the same temperature over the weekend. Temperatures are expected to soar across Utah and into parts of Wyoming and Idaho, where forecasters are calling for triple-digit heat in the Boise area.
Cities in Washington state better known for cool, rainy weather should break the 90s next week, while northern Utah -- marketed as having "the greatest snow on Earth" -- is expected to hit triple digits.
"This is the hottest time of the year but the temperatures that we'll be looking at for Friday through Sunday, they'll be toward the top," said National Weather Service meteorologist Mark O'Malley, adding, "It's going to be baking hot across much of the entire West."
Jennifer Smith, a spokeswoman for the National Interagency Fire Center based in Idaho, said crews are especially worried about wildfires igniting in the Four Corners region where the borders of Colorado, New Mexico, Utah and Arizona intersect.
Some of the strongest parts of the high pressure system are expected to be parked over the area through the weekend, where forecasters are calling for lightning but little to no precipitation, Smith said.
Scientists say that the jet stream, the river of air that dictates weather patterns, has been more erratic in the past few years. It's responsible for weather systems getting stuck, like the current heat wave. Scientists disagree on whether global warming is the cause of the jet stream's behavior.
The hottest cities are taking precautions to protect vulnerable residents. Police are pleading with drivers not to leave children or pets in vehicles, and temporary cooling stations are being put up to shelter homeless people and the elderly on fixed incomes who hesitate to use air conditioning.
Officials said extra personnel have been added to the U.S. Border Patrol's Search, Trauma, and Rescue unit as people illegally crossing the border from Mexico into Arizona could succumb to exhaustion and dehydration. At least seven people have been found dead in the last week in Arizona after falling victim to the desert's brutal heat.
Even airlines are watching the mercury for any signs that temperatures could deter operations.
In June 1990, when Phoenix hit 122 degrees, several airlines, including America West, which later merged with US Airways, were forced to cease flights for several hours because the planes didn't have the data needed to know how they would fly in temperatures above 120 degrees.
US Airways spokesman Todd Lehmacher said the airline's fleet of Boeings can now fly up to 126 degrees, and up to 127 degrees for the Airbus fleet.
But the company's smaller express planes flying out of the Phoenix area may be delayed if the temperature tops 118 because as the air heats up, it becomes less dense and changes liftoff conditions.
"The hotter is it, your performance is degraded," Lehmacher said. "We're monitoring this very closely to see what the temperatures do."
Officials at Salt River Project, the Phoenix area's largest electricity provider, also are closely monitoring usage in order to redirect energy in case of a potential overload.