Runoff Season and Snowpack Measurements

CASM Stakeholders

Rivers are rising, snow is melting, and runoff season is in full-swing! CASM and the ASO team have been working hard to deliver snowpack measurements and balance stakeholder needs and the complicated logistics of flying this many basins at such a high resolution. The wet spring has also been a challenge, with limited clear days available for flights. Our weekly flight coordination call hosted by Erik Skeie at the CWCB is where we have planned around these issues to deliver you all the flight coverage best for your agency.

Below are some of the detailed data from this record-setting snow year. As a reminder, all data can be downloaded by accessing the ASO Inc. data portal here (requires a free account): https://data.airbornesnowobservatories.com/

WRF-Hydro Forecasts

NCAR has developed an initial set of streamflow forecasts using its WRF-Hydro model that ingests ASO data to inform and improve those forecasts. In the report below, the seasonal water supply forecast values presented are the median (Q50) forecasts for April-July. The Dolores, Rio Grande and Conejos basins also have Apr-Sep forecast values provided. We are working on processes to provide the full set of (90%, 75%, 50%, 25%, 10%) exceedance probability forecasted flow values in a tabular format for future reports and hope to have that available soon.

This report is a work in progress with several of the new basin forecasts (e.g. Upper South Platte River and Front Range system) still being built for the new sites. Additionally, a handful of sites from the Upper Colorado/Windy Gap domain are now being re-calibrated with available unregulated flow data where it is available.

5/10/2023 WRF-Hydro ASO-Informed Streamflow Forecast (PDF)

M3 Works iSnobal Modeling Reports:

This week M3Works produced another round of ASO-informed snowpack reports for all basins that have received snow surveys this year. These reports show the modeled snowpack within each major ASO basin as of May 16th. All reports include the use of ASO data to inform and correct the model results. Reports are all downloadable here:

Upper Colorado: Blue River, Roaring Fork River and Fryingpan Headwaters, Windy Gap/Fraser

South Platte: Clear Creek, Boulder Creek, South Platte Headwaters

Gunnison: East River, Taylor River, Lottis Creek

Southwest: Dolores River

Rio Grande: Conejos River

The Poudre River and St. Vrain Creek have not had reports produced yet, pending data from ASO flight on 5/22/2023.

Snow Depth and SWE Data

The primary products generated through an ASO survey are a 3m resolution gridded snow depth (units in meters) and a 50m resolution gridded snow water equivalent (units in meters). These data are summarized across basins in the ASO data reports, but they are available for your own download and analysis as well.

Here is a detailed webmap of both the snow depth and SWE data collected so far this year

You can browse the 3m snow depth data in the map below as well. A reminder that each snow survey was collected on a different date. Differences in snow depth between basins has more to do with the date of survey than the climate conditions.

Thank you for your continued engagement and don’t hesitate to reach out with questions.

The CASM Team