A snow drought in the western United States is raising concerns about an early and intense wildfire season, according to an April 19 report. The National Integrated Drought Information System described the situation as “unprecedented” during a Feb. 23 briefing, noting that drier and warmer winter weather led to significantly reduced snowfall.
This development is important because lower snowpack means less soil moisture, which can increase vegetation stress and make conditions more favorable for wildfires. Economic impacts have already been felt in some states where ski resorts closed earlier than usual due to the lack of snow.
The U.S. Department of Agriculture’s Climate Center reported on Feb. 26 that “below-average snow water equivalency remains a concern in much of the west, even in drought-free areas such as the Sierra Nevada.” In Arizona, New Mexico, and Oregon, levels were reported at less than half their normal values. By April 2, the USDA confirmed that these low levels persisted across many western states.
Desert Research Institute Director Tim Brown said during a briefing for NIDIS: “The snowpack can definitely drought-stress the vegetation from the reduced soil moisture.” Brown also said: “There may also be a feedback process where that drought stress also increases the atmospheric drying … that exacerbates what the fire outcome might look like.”
Researchers are calling for more studies into how changes in snow cover affect wildfire severity. A University of Toronto team wrote in December: “Improved understanding of how snow dynamics affect burn severity will help inform resource allocation (e.g., funding, monitoring, personnel), fuel reduction, and forest management strategies to reduce the risk of high-severity wildfire and maintain forest ecosystem health and function.”
