Early snowfall levels prompt concerns about sinking #RioGrande water levels — El Paso Matters #snowpack

Western U.S. Drought Monitor map December 7, 2021.

From El Paso Matters (Danielle Prokop):

Unseasonably warm temperatures and low chances of significant winter precipitation have deepened concerns among regional water experts and farmers that extended drought conditions will compound stress on the Rio Grande, a key source of water for wildlife, agriculture and the city of El Paso.

Climate change has already decreased snowfall levels in the mountains and raised temperatures in the region…

Alex Mayer, director at the Center for Environmental Resource Management at the University of Texas at El Paso, said he’s watching for drought impacts to the Rio Grande, the sole regional source of surface water for irrigation and a significant portion of El Paso’s drinking water.

“We’re most concerned with the headwaters of the Rio Grande, where the snowpack is,” Mayer said. “The vast majority of the river water that does reach us comes from that snowmelt in the southern Colorado, northern New Mexico headwaters.”

[…]

Mayer said the season could still see storms, but the chances are low for the near future. Predictions from the National Oceanic and Atmospheric Administration expect hotter and dry conditions for at least the next month, raising alarms for the snowpack’s chances.

Westwide SNOTEL basin-filled map December 9, 2021.

Low snowpack

Karl Wetlaufer, a hydrologist with the federal Natural Resources Conservation Service, monitors and measures snowpack in Colorado to forecast the spring and summer runoff downstream.Wetlaufer said Rio Grande headwaters in Southern Colorado have seen 55% of the normal amount of rain and snow in October and November, and the snowpacks are only 30% of their normal size.

Wetlaufer said it’s early in the season as the peak snowpack usually develops through April. But even large snowpacks may not be enough to move the Rio Grande out of its water deficit. The hot and dry summers suck the moisture out of the soils, and absorbing snow melt before it makes it into a river channel compounds the drought conditions further,Wetlaufer said.

He used a simple analogy: If there is 100% of snowpack there is nearly 100% more water in the river, but the dry soil can absorb 20% or more. That means the river would only be 80% higher.

With two dry and hot years in a row, that translates to less snowmelt for the Rio Grande.

“We are going into winter with pretty considerable drought conditions,” Wetlaufer said. “We’re definitely anticipating streamflow to be much, much lower than usual relative to whatever snowpack we do see in the mountains.”

Federal forecast predictions show Colorado and New Mexico will most likely see warmer, drier conditions through February due to the La Niña weather pattern. La Niña describes a cooling of ocean surface temperatures in the Pacific Ocean that shapes weather around the world.

John Fleck, a professor in the Water Resources Program at the University of New Mexico, said La Niña shifts the odds against a wet winter in the West.

“It’s like we’re playing with a loaded dice, and it’s more likely to come up dry this winter,” Fleck said.

Rio Grande and Pecos River basins. Map credit: By Kmusser – Own work, Elevation data from SRTM, drainage basin from GTOPO [1], U.S. stream from the National Atlas [2], all other features from Vector Map., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11218868

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