Peak SWE and ASO-Informed Runoff Forecasts
The ASO survey season is well underway and the flight team has currently completed eight snow surveys in Colorado. For your convenience, data products and reports from these surveys have been linked below.
Across Colorado, the NRCS basin-average snow water equivalent (SWE) appears close to the historical average, though ASO flights have confirmed lower overall snowpack, especially in lower elevation areas without SNOTEL coverage. During our recent April Stakeholder meeting, ASO Formulation Lead Jeff Deems talked about how SNOTEL sites and basin average SWE estimates can look very similar between two years, but ASO snow surveys can reveal dramatically different snowpack measurements (link to relevant portion of video here).
In some places, the ASO-informed WRF-Hydro Forecast is showing significantly different runoff when compared to the official CBRFC forecasts. Validating this trend, the experimental ASO-informed forecasts issued by the CBRFC show agreement with the current WRF-Hydro model output as well. CBRFC official runoff forecasts show near or below average runoff, and the ASO-informed forecasts predict even lower runoff than the official forecasts in some basins, though there is still significant uncertainty in springtime precipitation events.
Peak SWE Snow Survey Flights
Initial snowpack measurement surveys have been conducted in many of Colorado’s headwater basins. Dozens of stakeholder groups provided input about the timing of these flights, most trying to capture conditions close to Peak SWE. The map below shows all of the basins that will receive snow surveys this year.
Data is currently available for each of the completed flights on the 2024 Activities page (the list below includes the date of the snow survey):
Poudre River mainstem (4/15/2024, Data pending delivery)
Colorado River at Windy Gap domain including the Fraser, Granby and Willow Creek basins (3/21-22/2024 and 4/14/2024, Data pending delivery)
Yampa and Elk (4/11/2024)
Roaring Fork (4/9/2024)
Taylor River (4/4/2024)
East River (4/3/2024)
Dolores (4/4/2024)
Conejos (4/2-3/2024)
More flights are scheduled to occur as runoff season progresses. Data and reports from future flights will be shared here as soon as they are available. ASO survey reports are typically available within 72 hours after a survey is completed, with WRF-Hydro forecasts and other products delivered 24-48 hours after that.
Data Products
All survey reports have been uploaded to the CASM website here:
The full datasets for each survey, including 3m gridded snow depth, 50m gridded SWE, 50m gridded albedo, and others, are available for download through ASO’s data portal here (free account required to access):
https://data.airbornesnowobservatories.com/
The Colorado Basin River Forecast Center (CBRFC) has begun issuing experimental runoff forecasts after each ASO flight. These forecasts incorporate ASO data through “direct insertion” of ASO snowpack data into their operational SNOW-17 model. These forecast reports can be found here:
https://www.cbrfc.noaa.gov/product/aso_2024.html
CASM continues to work towards integration of ASO data into the official Weather Service forecasts. As of now, ASO-derived forecasts should not be considered replacements for official CBRFC forecasts. ASO-derived forecasts may be used as supplemental guidance to enhance water managers’ understanding of local hydrologic conditions. Official runoff forecasts from the CBRFC and other RFCs that serve Colorado basins can be found here:
https://www.cbrfc.noaa.gov/wsup/graph/west/map/esp_map.html
CASM Usage Survey
Lastly, If you have 5 minutes, please consider completing this short survey on your general awareness of ASO data products, how they can be used in water management decision-making, and overall CASM program direction.
Thank you for your continued engagement
The CASM Planning Team
