NASA Data Feeds River Forecasts as Snow Drought Effects Linger

In the wake of the 2026 snow drought in the western United States, NASA's Earth observation data is now crucial for machine-learning forecasts that inform critical decisions regarding water, power, and public safety in Washington state. Tacoma Power, a local utility, is utilizing river-flow predictions from a U.S. technology company to navigate a year of unusual water conditions on the Cowlitz River. Their main hydroelectric project, powered by the Mayfield and Mossyrock dams, supplies electricity to over 151,000 homes annually.

Upstream Tech's HydroForecast system integrates weather forecasts and river measurements with satellite data from NASA, specifically focusing on snow cover and vegetation health. This allows for predictions of river flow from several hours to days in advance. These forecasts, updated every two hours, are vital for reservoir managers, hydropower producers, water utilities, and government agencies to prepare for storms, manage reservoir releases, and cope with periods of low water availability.

"A key part of NASA's mission is to translate observations from space into practical benefits on the ground," stated Erin Urquhart, manager of NASA's Water Resources program. "When a U.S. company integrates NASA's freely accessible data into forecasts that help water managers prepare for floods, generate power, and conserve water resources, it demonstrates NASA's delivery of tangible value to the nation."

A Year of Water Extremes

The winter of 2025-26 saw unusually warm temperatures across the western U.S., leading to more precipitation falling as rain rather than snow. This, combined with below-normal precipitation in some regions, exacerbated existing water deficits. Data from NASA's MODIS (Moderate Resolution Imaging Spectroradiometer) satellite indicated that January, February, and March of that year recorded the lowest Western snow cover for those months in the satellite's record dating back to 2001.

On the Cowlitz River, these conditions resulted in a year of extremes. In December 2025, a potent atmospheric river brought a substantial amount of moisture, causing one of the largest single-day inflow surges ever recorded at Tacoma Power's hydroelectric facility. The persistent rain-heavy pattern meant that water flowed downstream rapidly instead of accumulating as mountain snowpack, which would have provided a steady water supply throughout the summer. Consequently, snowpack levels remained critically low, at only 20% to 50% of normal.

As winter transitioned to spring, the rainfall diminished, and by April 8, Washington state declared a drought emergency across all its watersheds, including the Cowlitz. From April through June, the peak daily inflow into the project was among the lowest ever recorded, leaving Tacoma Power with insufficient water to replenish its reservoirs for the anticipated summer demand, according to Saul Villarreal, Tacoma Power’s senior hydro operations manager.

Translating Satellite Data into River Forecasts

NASA processes data from the VIIRS (Visible Infrared Imaging Radiometer Suite) instrument on the Suomi-NPP satellite to provide information on snow cover and vegetation greenness across entire watersheds, even in areas lacking ground monitoring stations.

To train its HydroForecast models, Upstream Tech compiles years of NASA data, weather forecasts, and actual river flow measurements. By analyzing data from hundreds of watersheds, the models learn how water moves through landscapes and can apply these patterns to new locations.

Dr. Laura Read, director of technical and federal partnerships for HydroForecast at Upstream Tech, noted that incorporating snow and vegetation data significantly improved forecast accuracy across multiple basins. "NASA's data offers the reliability, global coverage, and consistency we require," she stated. "Our short-term models update every two hours, so these inputs must be consistently available. Any disruption to our operational pipeline is a major concern."

Tacoma Power utilizes HydroForecast in conjunction with stream gauges, snow monitoring stations, and the expertise of its operators. During the December storm, the NASA-informed forecast enabled the utility to anticipate water inflows, manage dynamic river conditions, meet operational requirements, and prioritize public safety, Villarreal explained.

As spring progressed, the challenge shifted to managing water scarcity. Tacoma Power's seasonal model predicted low runoff, prompting them to maintain higher reservoir levels than usual to conserve water for summer. This reduced reservoir capacity meant less room for potential large storms, so operators continuously monitored short-term forecasts to stay prepared for changing conditions and potential atmospheric rivers.

"The earlier we can anticipate potential changes in conditions, the more effectively we can plan our reservoir management and balance the various demands on our system throughout the season," Villarreal added.

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

From Forecasts to Drought Assessments

The Cowlitz Hydro Project at Tacoma Public Utilities is just one illustration of how NASA's scientific contributions are aiding water management decisions across the western U.S.

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

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

NASA's data and research have long influenced the U.S. Drought Monitor, a weekly assessment used by farmers, water managers, and public agencies. NASA became a formal partner in 2026, expanding its role from data provider to contributing to the assessment's production. The agency took its first lead role in authoring the Drought Monitor during the week of August 17.

Discover more about NASA’s drought work

About the Author

Emily DeMarco is a writer and editor with NASA’s Earth Science Division. With over a decade of experience in science journalism and communication, she previously served as deputy news editor at Science News magazine. Emily holds a master's degree in environmental science and management from UC Santa Barbara's Bren School, where she focused on 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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