Dangerous heat forecast for weekend | TheUnion.com

Dangerous heat forecast for weekend

Heat forecast poses danger

The National Weather Service predicts temperatures in the mid-90s by Thursday, and triple digits throughout the weekend — a danger for wildfire and people with already existing cardio-pulmonary disease.

“It’ll be especially hot for the foothills because overnight cooling will only get down to the mid- to high 70s,” said Cory Mueller, National Weather Service meteorologist. “It’s typical for the foothills to cool down to an average low of 57 degrees, so you’ll be well above average.”

Mueller cautioned people to guard against heat exhaustion. Symptoms can include dizziness, fainting, excessive sweating, pale and clammy skin, and muscle cramps.

“When you get into that situation it’s much easier to get heat exhaustion or heat stroke,” said Mueller. “The latter can result in headaches, but no sweating, yet a fever with a body temperature of 103 or more. You should call 911 at this point because you’ll need medical attention.”

Heat is also one of the elements that can contribute to wildfires, said Mary Eldridge, Cal Fire public information officer.

“Heat is certainly a factor,” said Eldridge. “Our fuel moisture level is extremely low now. There’s been very little precipitation, little snow pack and we’ve had significant wind events — all affecting fire danger.”

Fire danger is also assessed by measuring the moisture levels of vegetation. Moisture levels are significantly down this year.

“We’re seeing moisture levels (now) from four to six weeks later in the year,” Eldridge said. And she added because of the varied topography of the county and micro-climates, there is a wide span of danger levels across the county.


Michelle Mead, of the National Oceanic and Atmospheric Administration, said that from Oct. 1 to May 31 the Northern Sierra 8-Station had its third driest water year (Oct.1 to Sept. 30) on record. Most locations in Northern California ranged from 40% to 60% of normal precipitation.

“Snowpack water content usually peaks around April 1,” said Mead. “However, the snow pack peaked in March. Warm spring temperatures and the lack of winter storms resulted in below normal statewide snowpack of 59% of normal.”

The first major heat event of the season occurred in late May when some Central Valley locations climbed above 100. And, according to the U.S. Drought Monitor, drought conditions have continued to expand across interior Northern California and range from extreme drought to exceptional drought. This is due to significant precipitation deficits from the 2020 and 2021 water years. Drought conditions are expected to persist through the summer.

Sam Longmire, air pollution control specialist of the Northern Sierra Air Quality Management District, said that typically with high temperatures the main problem with air quality is elevated levels of ozone concentrations.

“Heat and sunlight favor creation of pollutants of nitrogen oxide, reactive organic gases and volatile organic compounds, largely from automobile exhaust and industrial processes,” he said.

Pollutants in Nevada County mainly travel from the Sacramento region, encouraged by heat and sunlight. Vulnerable individuals are advised to limit their outdoor activity. Ozone levels exceed federal standards when there are 70 parts of ozone to 1 billion parts of air.

“It’s like a nickle on a football field,” said Longmire. “The air district advises to exercise in the morning rather than the afternoon. But we’ve had a pretty good year so far with only three days over the federal standard.”

Ben Hatchett, assistant research professor of atmospheric sciences at the Desert Research Institute in Reno, predicted a very hot year.

“There’s a potential this year to break maximum temperatures,” he said. “It’s going to be very hot because of low humidity.”

What that does, in turn, is lessen the cooling effect known as humidity recovery that occurs at night. But with scorching afternoon temperatures, nighttime, although cooler, still has little humidity and that raises potential for fire danger.

“It’s a cascading effect in a heat wave,” said Hatchett. “Demand on the power grid causes the electricity to go out or be cut by power companies. So, people turn on generators that can cause fires in dry, grassy areas. It’s a good time to be extra careful. Stay in the shade, drink plenty of water and check on people who may not know how to take precautions.”

William Roller is a staff writer with The Union. He can be reached at wroller@theunion.com

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