A look at weather extremes and the big-picture climate connections.

Record Fires and Floods Threaten Southwest, Upper Midwest

Being put on evacuation notice is a terrible way to spend a weekend, but that’s the prospect thousands of residents in both Arizona and parts of the Central U.S. are facing today, albeit from two very different threats.

Hundreds of thousands of acres continue to burn in eastern Arizona's Wallow Fire, prompting residents of Springerville and Eagar to evacuate their homes. Credit: Eric Thayer/Getty Images

In drought-ridden Arizona, a week of warm weather and strong winds stoked the Wallow Fire, which is burning near the state’s eastern border with New Mexico. By last Sunday, the fire had burned 365 square miles, but according to the fire’s incident website, that area nearly doubled in just the past five days, due to hot and windy weather. Now covering more than 640 square miles, the Wallow Fire is so far listed as the second largest wildfire in Arizona’s history — and it may get bigger before firefighters manage to contain it.

While the 20 to 30 mile-per-hour winds (with higher gusts) that fanned the wildfire earlier this week have since died down, Weather Underground meteorologist Jeff Masters predicts that more warm, dry and windy weather forecast for today and tomorrow will expand the fire’s range and surpass the area burned by the 2002 Rodeo-Chediski fire. Smoke from the Wallow Fire, along with another immense southern-Arizona fire called Horseshoe Two, has already spread northeast across New Mexico and Colorado, and as far as the Ohio Valley.

Meanwhile, thousands of miles to Arizona’s northeast, record floods along part of the Missouri River have forced hundreds of residents of North Dakota, Iowa, and Nebraska from their homes. On Friday, Reuters reported that six dams between Fort Peck, Montana and Gavins Point, South Dakota, have already or will soon reach their record releases of water. By the middle of June, the Army Corps of Engineers and National Weather Service expect the amount of water flowing through the Gavins Point Dam to put the entire area of the river downstream of the dam well above flood stage.

The sudden melting of heavy winter snowpack in the mountains of Montana have contributed to this year’s high water levels. In some parts of the northern Rockies, winter and spring snowpack this year was more than four times the typical amount. Temperatures in the past month have warmed quickly in the West, which has sent a surge of water into the Missouri. Heading into this weekend, rain is in the forecast for North Dakota, South Dakota, and Nebraska, and this may further increase the flood’s severity.

Both the Arizona drought and Missouri River floods are also linked to the recently diminished La Niña conditions in the tropical Pacific Ocean, which influenced weather patterns this past winter. La Niña tends to result in drier than average winters in the Southwest, and wetter (and snowier) than average conditions in the Pacific Northwest and parts of the Rocky Mountains. Long-term climate change is also expected to lead to more wildfires in parts of the West, as well as more intense and longer-lasting droughts. Earlier and more rapid spring snowmelt is already taking place in the West as average temperatures increase, leading to an increased likelihood of spring flooding events. (However, this year the snowmelt has been delayed in Montana and other parts of the West, as cold air remained locked in place through May.)

Recent studies have also shown that manmade global warming is leading to an increase in heavy rainfall events in North America, so more frequent flooding events such as what occurred earlier this year along the Mississippi River, and now along the Missouri, are expected. 

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