NASA Data Feeds River Forecasts Amid Lingering Snow Drought Effects

As the repercussions of the 2026 snow drought in the western United States persist into the summer, NASA's Earth observation data is actively contributing to machine-learning-driven forecasts. These forecasts are instrumental in guiding critical decisions regarding water management, power supply, and public safety in Washington state.

Tacoma Power, a public utility in Washington, is leveraging advanced river-flow predictions from a U.S. technology firm during a year characterized by extreme water conditions on the Cowlitz River. The utility's primary hydroelectric facility relies on water stored in the Mayfield and Mossyrock dams to generate enough electricity to power over 151,000 homes annually.

Upstream Tech's HydroForecast system integrates weather predictions and real-time river measurements with satellite data from NASA, which provides information on snow cover and vegetation health. This integration allows for river flow predictions ranging from hours to days in advance. The forecasts, updated every two hours, are vital for reservoir managers, hydropower producers, water utilities, and government bodies to prepare for impending storms, strategize water releases from reservoirs, and navigate periods of water scarcity.

"A key part of NASA's mission is to translate space-based observations into practical applications for people on the ground," stated Erin Urquhart, manager of NASA's Water Resources program at the agency's headquarters in Washington, D.C. "When an American company integrates NASA's freely accessible data into forecasts that assist water managers in preparing for floods, generating power, and conserving water supplies, it demonstrates NASA's tangible value to the nation."

A Year of Water Extremes

During the winter of 2025-26, unseasonably warm temperatures led to a greater proportion of precipitation falling as rain rather than snow across much of the western U.S. Concurrently, below-average precipitation exacerbated water deficits in some regions. January, February, and March of that year recorded the lowest snow cover in the western U.S. for those months in the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite record, which began in 2001.

On the Cowlitz River, these conditions resulted in a season of stark contrasts. In December 2025, a powerful atmospheric river brought a concentrated band of Pacific moisture to the region, triggering one of the most significant one-day surges in inflow ever recorded at Tacoma Power's hydroelectric facility. Throughout the season, this rain-dominant pattern caused water to flow downstream rapidly, rather than accumulating as mountain snowpack that would gradually melt and supply water through the summer. Snowpack levels remained substantially below normal, between 20% and 50% of average.

As winter transitioned into spring, the rainfall diminished. On April 8, Washington state declared a drought emergency, affecting all watersheds, including the Cowlitz. From April through June, the peak daily inflow into the project was among the lowest on record, leaving Tacoma Power with insufficient incoming water to adequately replenish its reservoirs before the peak summer demand, according to Saul Villarreal, Tacoma Power's senior hydro operations manager.

Translating Satellite Data into River Forecasts

NASA converts observations from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the Suomi-NPP satellite into data products that offer insights into snow cover and vegetation greenness across entire watersheds, even in areas with limited ground monitoring stations.

To train the HydroForecast system, Upstream Tech compiles and archives years of NASA data products, alongside weather forecast data and actual river flow measurements. By analyzing historical data from hundreds of watersheds, the models learn typical patterns of water movement through landscapes and apply this knowledge to new areas.

Testing across multiple river basins has demonstrated that incorporating snow and vegetation observations significantly improves forecast accuracy, noted Dr. Laura Read, director of technical and federal partnerships for HydroForecast at Upstream Tech. "NASA's data provides the reliability, global coverage, and consistency we require," Read stated. "Our short-term models run every two hours, so these inputs must be available precisely when needed. While we have backup systems, any interruption to our operational pipeline is highly consequential."

Tacoma Power utilizes HydroForecast in conjunction with stream gauges, snow monitoring stations, and the expertise of its operators. During the December storm event, the NASA-enhanced short-term forecast enabled the utility to accurately anticipate water volumes and prepare for dynamic river conditions, while ensuring compliance with operational requirements and prioritizing public safety, Villarreal added.

As spring approached, the operational challenge shifted. Tacoma Power employed HydroForecast's seasonal model to monitor the increasing risk of low runoff and proactively maintained higher reservoir levels than usual to conserve water for the summer. This strategy reduced available storage capacity for potential large storms, necessitating continuous monitoring of short-term forecasts to "play defense" and remain prepared to adjust operations should another atmospheric river develop.

"The earlier we can understand how conditions might evolve, the more effectively we can plan to manage our reservoirs and balance the diverse demands of our system throughout the season," Villarreal remarked.

Despite the dry spring, Tacoma Power entered the summer of 2026 with reservoir levels near the average. This stored water ensures reliable hydropower generation, maintains necessary river flows to support aquatic habitats, and facilitates public recreation. It also provides the utility with greater flexibility to meet electricity demand during heat waves or unexpected outages, and to support the broader regional power grid when possible.

From Forecasts to Drought Assessments

The Cowlitz Hydro Project operated by Tacoma Public Utilities serves as just one illustration of how NASA's scientific advancements are supporting water management decisions across the western United States.

NASA has also collaborated with the U.S. Department of Agriculture's Natural Resources Conservation Service to integrate satellite-derived snow and groundwater data into machine-learning models for water supply forecasting.

The National Oceanic and Atmospheric Administration's Colorado Basin River Forecast Center incorporates MODIS and VIIRS data to refine snowmelt rate calculations in its models. The Bureau of Reclamation utilizes NASA and NASA-derived snow data, along with other sources, for reservoir operations in California's San Joaquin Basin.

NASA's data and research have long contributed to the U.S. Drought Monitor, a weekly assessment relied upon by farmers, water managers, and public agencies. NASA formally joined as a partner in 2026, expanding its role from data provision to actively contributing to the assessment's production. The agency took responsibility for authoring the Drought Monitor during the week of August 17.

Discover more about NASA’s drought work

Emily DeMarco, Writer/Editor (IV), Earth Science Division, is the author of this article. Emily is a science writer and editor with NASA’s Earth Science Division, with more than 10 years of experience in science journalism and communication. A former deputy news editor at the magazine Science News, she holds a master’s in environmental science and management from UC Santa Barbara’s Bren School, where she specialized in water resources management and science communication.

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Last Updated: Aug 20, 2026

Related Terms: Goddard Space Flight Center, Droughts, Earth, Earth's Atmosphere, Water on Earth

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