Can North Texas expect a heat wave like the one that broiled the Pacific Northwest?
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 wont 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 earths surface. The air becomes compressed, causing temperatures to rise. Lola Espinoza poured water for a dog as temperatures surged in Yakima, Wash., on Monday. (Amanda Ray)  The high-pressure system in the recent scorching heat wave was created by large waves in the atmospheres 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 Centers latest report. The impact of El Nio and La Nia  High-pressure systems arent new to North Texas, but theyre most prominent in late July and early August, according to Lamont Bain, a meteorologist for the National Weather Service in Fort Worth. Thats actually our hottest time of the year, Bain said. And a lot of times thats a result of very strong high pressure, just kind of being in control of the weather across our region.  In North Texas, its worth keeping an eye open for the development of El Nio or La Nia weather patterns in the Pacific Ocean. El Nio, when trade winds weaken, and La Nia, when trade winds strengthen, can dramatically affect weather worldwide. Both events, Cook said, can indicate that periods of extreme weather are likely. La Nia 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 Nio and La Nia 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 planets warming, Cook said. But that one particular mechanism thats 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 areas 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 Centers 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. Children played in a cascade of water at the Frog Pond Water Park at Farmers Branch Aquatics Center last August. (Smiley N. Pool / Staff Photographer)  Bain said the centers 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 doesnt 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 isnt as bad. For those who work or play outdoors, its 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.