Snowpack is one of the biggest unknowns in water planning. You might hear things about it being a good or bad snow year, but that doesn’t tell you where the water actually is, how it’s distributed, or what exactly it means for runoff timing in your particular basin.
Snow Water Equivalent (SWE) gets at the core question: how much water would you get if the snow melted? But SWE isn’t uniform. Lower elevations may already be melting while higher elevations are still accumulating, and a single basin-wide number hides that variability (we’ve seen lots of recent examples of local variation like this).
The new Snow Water Equivalent (SWE) analysis tool in the HydroForecast dashboard is designed to make variability visible. By comparing current conditions against 45 years of historical data, this tool gives you the context to understand whether this year is truly unusual — and at which elevations — so you can make more confident operational decisions rather than planning around a number with no frame of reference.
The new SWE analysis tool in the HydroForecast dashboard breaks snowpack down by elevation band so you can see:
The analysis is powered by SWANN (Snow Water Artificial Neural Network) data, which blends long-term in-situ measurements (like SNOTEL and COOP stations) with PRISM climate data. This allows you to compare current conditions against a long historical record with confidence. SWE analysis is currently available for U.S. locations.
Each SWE analysis chart answers a different question about the snowpack and together, they give you context you can plan around.
This view compares current SWE to 45 years of historical data for each elevation band to help users see how this year is similar or different. Each box shows the typical range of conditions at that elevation, with a line indicating the historical median. The current year is plotted as a red marker, making it easy to see where today’s conditions fall within — or outside of — that range.
This makes it quick to spot whether snowpack is within the normal range and, just as importantly, which elevations are driving any differences. In many cases, this is where early signals show up: a basin might look “normal” overall, while specific elevation bands tell a different story.
This chart compares the current year to selected historical years, including high and low snowpack scenarios, to get a sense for the closest corollary year to this year. Each line represents a different year, with the current year highlighted so you can easily track how it’s evolving. You can also interact with the legend to highlight specific years and compare patterns more directly.
Rather than focusing on a single value, this view helps you recognize patterns. You can see whether this year is tracking like a known wet year, a dry year, or something in between — and adjust expectations accordingly.
This chart compares current SWE to the historical average at each elevation band. Current conditions are shown as bars, with the historical average overlaid for reference. Hovering on a bar reveals the percent of normal for that specific elevation.
This is the fastest way to understand where surpluses or deficits exist. Instead of relying on a single basin-wide percentage, you can see which elevations are contributing most to that number—and how that might affect runoff timing and water availability.
Snowpack isn’t just about how much water exists, it’s about when and how that water will show up in rivers and streams over the course of the year.
By breaking SWE down by elevation, these charts help you anticipate runoff timing more accurately, identify early signals of unusual conditions, compare current conditions to known historical scenarios, and make more informed operational decisions. Instead of relying on a single number, you get a clearer picture of what’s happening across the basin — and what it means for what comes next.
Ready to integrate SWE analysis into your operational planning? Talk to our team to get started with HydroForecast and explore our full range of resources for operating in snow-driven basins.
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