Ag Weather Forum

Winter Was Poor for Snow Moisture in Southwestern US

Bryce Anderson
By  Bryce Anderson , Ag Meteorologist Emeritus
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Moisture from snow melt is almost zero in the southwestern U.S. going into spring. That dryness especially affects the Colorado River basin. (NOAA/NIDIS graphic)

The latest weather and climate agency drought status update and outlook for the western United States started with a harsh statement: "Abysmal Snow Defines Winter for Arizona and New Mexico." The report is published monthly between December and June and is a collaboration between the National Oceanic and Atmospheric Administration (NOAA) and the National Integrated Drought Information System (NIDIS). State climate agencies also contribute to this report. The report is based on conditions as of March 3, 2025. The NOAA/NIDIS report also includes an outlook for the balance of the snow season in the western U.S.

Key points from the outlook include:

"Another month of extremely dry conditions plagued the Southwest (Colorado, New Mexico, Arizona, Utah, Nevada), leading to deepening snow deficits across already dry basins. Exceptional snow drought continues to persist with the peak snow water equivalent (SWE) dates past for Arizona and New Mexico.

"The Upper San Juan, Upper Rio Grande, and Gunnison River Basins provide substantial snowmelt and runoff to the Upper Colorado River Basin, which drains into Lake Powell. Given low snowpack in these basins, monitoring snow conditions will be critical for future water supply as the basins enter the spring snowmelt season.

"Moderate snow drought conditions persisted in the northern and central Cascade Range of Washington due to below-average winter precipitation.

"A recent storm cycle brought welcome moisture back to California and Nevada, improving snow drought conditions, but deficits still remain in the region."

In total, 62% of the western contiguous U.S. had below-median snow water equivalent as of early March.

The impact of poor snow cover and subsequent snow-melt moisture in the Colorado River is especially acute. The NOAA/NIDIS report noted that "The U.S. Bureau of Reclamation weekly water supply report for the Lower Colorado River Basin predicts unregulated inflows into Lake Powell will be 70% of normal in April-July. This is despite 92% of normal snow water equivalent (SWE) in the Upper Colorado Basin, as Colorado river tributary watersheds across central Utah (the San Juan River Basin, the Green Basin, and Gunnison Basin) saw below-normal precipitation and persistent low soil moisture conditions. Spring storms could help boost snowpack, but erasing the deep seasonal deficits across these basins is unlikely."

It's also been very dry in Alaska because of warm and dry conditions. The NOAA/NIDIS report mentioned the airport in Anchorage logged its driest February on record. In addition, large areas in southwest Alaska and low elevations in south-central Alaska were nearly snow-free as of March 1. Those areas are typically snow covered.

Forecast models suggest a colder and wetter pattern during at least the next couple weeks in the western U.S., which could offer some late-season snow accumulation. That prospect will be closely monitored because of the dry conditions coming out of the meteorological winter season.

The full report is available here: https://www.drought.gov/…

Bryce Anderson can be reached at bryce.anderson@dtn.com

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