The Greater Yellowstone Drought Continues

Much of Greater Yellowstone was treated to a late-season snowstorm earlier this week, topping off what was largely a low snow year courtesy of the winter’s El Niño weather pattern. Despite this week’s storm however, it’s likely that the above average temperatures and below average precipitation that characterized much of the winter months will persist through spring and summer in the region, according to the National Weather Service.

Water is a critical resource in the West with implications for agriculture, recreation and, of course, wildfires. As spring runoff begins, Mountain Journal spoke with Montana-based Natural Resources Conservation Service hydrologist Eric Larson and Wyoming-based NWS meteorologist Chris Jones to break down what recent outlooks mean for Greater Yellowstone.

Larson explained how summer water supply is closely tied to winter snowpack. Currently, Greater Yellowstone is experiencing drought conditions ranging from abnormally dry to severe drought, according to the May 9 U.S. Drought Monitor, and snowpack varies across the region.

Northwest Wyoming and eastern Idaho are faring better than southwest Montana in terms of snow water equivalent, the amount of water available in the snow, per SNOTEL data from NRCS. Conditions in the Upper Snake, Snake Headwaters and Big Horn river basins are consistent with the 30-year average for snow water equivalent, while the Missouri Headwaters and Upper Yellowstone basins hold roughly 80 percent of the average for this time of year.

“It was really, really dry from November through mid- to late January, especially in the Greater Yellowstone Area,” Larson said. “Lower snow years generally result in a lower runoff.”

Pairing the below-average snowpack with predictions for a warm, dry couple of months will likely result in persistent drought conditions across the region, according to the NWS Seasonal Drought Outlook.

Historically, El Niño years such as 2023-2024 will bring warm, dry conditions persist through August and then transition into a cooler, wetter fall and early winter as the La Niña cycle begins, Jones said. Three-month seasonal outlooks released by the NWS in mid-April predict a 50-60 percent chance of above average temperatures and a 40-50 percent chance of below average precipitation from June through September in southwest Montana, northwest Wyoming and eastern Idaho.

Potential implications of low water supply include water-use ordinances and fishing restrictions, according to Larson. The good news? The National Interagency Fire Center’s wildfire outlook predicted normal fire conditions in Greater Yellowstone through August per its May 1 outlook. Areas just west of Greater Yellowstone in central Idaho are predicted to experience higher wildlife danger.

“We're trying to look over a 90-day period, which is a lot of time in the world of weather,” Jones said. “But at least right now, it's shaping up to be a normal [fire] season. Late July and August is when we would expect to see some wildfires that could erupt.”

Weather conditions can always vary from predictions and it just takes a single dry lightning storm or spell of wet weather to drastically change the fire outlook, Jones explained. For now, a warm, dry spring and summer appears likely for Greater Yellowstone.

EDITOR'S NOTE: Read more MoJo coverage of winter 2023-2024's low precipitation here.

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