#Drought/#runoff news: Parts of SW #Colorado slip back into Extreme Drought, #AnimasRiver runoff expected to peak early

From The Durango Herald (Jonathan Romeo):

Extreme drought has crept back into Southwest Colorado…

“With climate change, we expect to see these really big swings from wet to dry years,” said Brad Udall, a senior water and climate research scientist with Colorado State University. “But the trend is we’re in a mega-drought.”

For context, Udall said it’s important to look at Colorado’s weather the past three years. In 2018, it was one of the hottest and driest years on record. The next year, however, brought one of the best snowpacks in recorded history.

For 2020, it appears the pendulum has swung back to hot and dry.

“It’s not as bad as 2018, but it’s still bad,” Udall said. “Probably within the bottom 10 driest years on record.”

West Drought Monitor May 5, 2020.

On Thursday, the U.S. Drought Monitor relisted parts of Southwest Colorado in the “extreme drought” category for the first time since the region was downgraded after the 2018-19 winter…

Southwest Colorado’s current dry spell began in October 2019 and lasted through the winter. Though high elevation weather stations recorded about normal snowpack levels, researchers estimated snow levels were below average.

This spring, too, has been all but void of precipitation. April saw just 10% of normal precipitation levels for the region, making it one of the driest months on record. From October to April, the region saw 70% of its average precipitation levels.

As a result, the Animas River is expected to have 63% of its normal water supply.

Unusually high temperatures, too, have exacerbated the lack of snow and rain. In April, for instance, the region was 10 to 20 degrees higher than average, according to data from the Colorado River Basin Forecast Center.

Above-average temperatures this early in the season have caused snowpack to melt and rivers to run higher and earlier than normal. The Animas River, for example, is expected to peak this weekend at around 2,700 cubic feet per second. By comparison, the Animas River usually peaks during the first week of June around 4,700 cfs.

Most of the snow has already melted off the San Juan Mountains – the Animas, Dolores, San Miguel and San Juan river basins have just 50% of normal snowpack levels for this time of year.

The hot and dry conditions have elevated concerns about fire danger in the region. Pugh said soil moisture is in the lowest fifth percentile, a sign that fuels on the ground are ripe to burn and would be difficult to put out.

Hal Doughty, chief of Durango Fire Protection District, said local fire chiefs in the region sent a letter Friday to La Plata County, requesting commissioners implement Stage 1 fire restrictions.

La Plata County commissioners are expected to vote on the restrictions Tuesday. The Southern Ute Indian Tribe implemented Stage 1 fire restrictions on Friday…

On April 7, the Forest Service announced a complete fire ban across 24 national forests in the Rocky Mountain region, including the San Juan National Forest.

Lorena Williams, spokeswoman for the Forest Service, said the agency is expecting above-average fire potential in May and June.

“Fuel dryness levels have hit critical levels, and above-normal fire potential exists at all snow-free elevations in Southwest Colorado,” she said. “We are preparing for active fire behavior that will be difficult to control. As we’ve seen very recently, any ignitions can lead to rapid fire spread when aided by wind and slope. As fuels dry even more, less wind and less slope will result in the same amount of spread.”

Udall said there is some connection between dry years and wetter monsoons later in the summer: The sun heats the land more, which pulls moisture-laden air from thousands of miles away.

“I don’t think there’s any question that happens,” he said. “But it’s just not a guaranteed thing. The odds are just higher.”

Udall pointed to a scientific study published April 17 in Science that concludes a drought of epic portions is the new reality for the American Southwest, driven in part by climate change…

Williams and his colleagues, however, found by studying soil moisture content in tree ring records that the region had experienced four periods of more than two decades of severe drought conditions in the past 1,200 years.

The study found the current drought in the region since 2000 is the second-worst drought experienced in that time span, second only to a dry spell in the 1500s.

Add complications with climate change, which is expected to move storms farther north and raise temperatures in the Southwest, and concerns about water availability and intensified wildfire seasons begin to mount.

“I’ve always been worried about Southwest Colorado,” Udall said. “As the planet warms, areas right on the edge of big deserts like Southwest Colorado are really at risk.”

San Miguel, Dolores, Animas, and San Juan Basin High/Low graph May 7, 2020 via the NRCS.

Leave a Reply