In recent days, the Pacific Northwest has been beset by a heat wave that the National Weather Service called unprecedented and historic.
With temperatures soaring into the 110s in places, Oregon, Washington and British Columbia have amassed hundreds of heat-related deaths, The New York Times reported.
Despite these weather patterns, meteorologists say North Texans won’t face similarly hazardous, record-setting heat — at least not in the immediate future.
Cause of Pacific Northwest heat wave
The National Weather Service has extended the excessive-heat warning for the Pacific Northwest until Sunday.
The heat wave out West was caused by a ridge of high pressure that diverted the normal weather systems in the region. The phenomenon is known as a weather “block.”
Kerry Cook, a climate expert who teaches at the University of Texas at Austin, said the high-pressure system pushes air closer toward the earth’s surface. The air becomes compressed, causing temperatures to rise.
The high-pressure system in the recent scorching heat wave was created by large waves in the atmosphere’s jet stream — the strong west-to-east current that occurs between polar regions and middle-latitude temperate regions, Cook said.
When those undulations, called Rossby waves, grow large enough, they can form blocks, which consist of high-pressure ridges that can cause extended periods of heat, Cook said.
The hot, dry conditions have triggered wildfires across the Pacific Northwest and in Canada. As of Friday, 11 states were battling 33 uncontained large fires, according to the National Interagency Coordination Center’s latest report.
The impact of El Niño and La Niña
High-pressure systems aren’t new to North Texas, but they’re most prominent in late July and early August, according to Lamont Bain, a meteorologist for the National Weather Service in Fort Worth.
“That’s actually our hottest time of the year,” Bain said. “And a lot of times that’s a result of very strong high pressure, just kind of being in control of the weather across our region.”
In North Texas, it’s worth keeping an eye open for the development of El Niño or La Niña weather patterns in the Pacific Ocean. El Niño, when trade winds weaken, and La Niña, when trade winds strengthen, can dramatically affect weather worldwide.
Both events, Cook said, can indicate that periods of extreme weather are likely. La Niña was the driving force of weather patterns in Texas during the scorching summer of 2011, according to research from the National Oceanic and Atmospheric Administration.
In early June, the National Weather Service, the Climate Prediction Center, the National Centers for Environmental Prediction and the International Research Institute for Climate and Society issued a report on the El Niño and La Niña patterns, stating that neutral conditions were favored for the summer. That means that neither of the extreme phases is likely to occur and that ocean surface temperatures will be close to average, according to NOAA.
“We always have to expect extreme temperatures, because the planet’s warming,” Cook said. “But that one particular mechanism that’s associated with extremely hot, dry temperatures in the summer over Texas is not developing currently.”
Moderate weather for D-FW in near term
For now, temperatures in Dallas-Fort Worth are below normal.
The average for the area’s first triple-digit day is July 1, but this year, North Texas may not hit 100 degrees or more until after Wednesday, KXAS-TV (NBC5) chief meteorologist Rick Mitchell said.
“The pattern remains favorable for cooler-than-normal weather for North Texas, even out through the first full week and a half of July,” he said.
According to the Climate Prediction Center’s forecast for July, which was issued Wednesday, North Texas has a 30% to 40% chance of below-normal temperatures. The Pacific Northwest region has a 50% to 70% probability of above-normal temperatures during the same period, the center predicted.
Bain said the center’s forecast is based on average temperatures, meaning extreme temperatures are still possible. He also said it is too early to predict what the exact weather pattern will be once a high-pressure area moves over the D-FW area.
Even without record-setting temperatures, the heat in the region can still be dangerous. According to Mitchell, typical North Texas summers average about 20 days of 100 degrees or higher.
“We will have our share of hot weather, but it doesn’t mean that it will be on par with what the Pacific Northwest was seeing,” he said. “There were some very specific circumstances involved in that, but we know Texas summers can be brutally hot when they want to be.”
As heat rises, so should precautions
Heat-related illnesses and deaths spike this time of year, Bain noted.
In May, MedStar transported 17 people to hospitals for primary heat-related issues, MedStar spokesman Matt Zavadksy said. In June, the number jumped to 106.
Bain recommended limiting summer exercise to early mornings or other times when the heat isn’t as bad. For those who work or play outdoors, it’s important to stay hydrated and take frequent breaks. And never leave children or pets unattended in vehicles during hot and warm weather, when interior temperatures can soar rapidly.
