Climatology tab¶
The Climatology tab compares this season with past seasons for a basin or catchment.
Using it¶
- Select a region: click a polygon on the small map. A toggle above it switches between area
levels, e.g.
BasinsandCatchments(the levels depend on the region). - Variable: choose what to plot, e.g. SWE, snow depth, snowfall or runoff.
- To Date / Full Season: zoom on the season so far, or show the whole season.
The main chart¶
| Trace | Meaning |
|---|---|
| Q5–Q95 range (shaded) | where 90 % of past seasons fell on each day |
| Median (Q50) | the typical season |
| WY |
this season so far |
| Forecast (dashed) | the coming days, from the deterministic forecast |
| WY |
last season, for reference |
"WY" means water year: the season label is the year in which it ends, so the season from September 2026 to August 2027 is WY 2027.
The rate-of-change chart¶
The second chart shows the daily change of the variable (e.g. Δ SWE per day): positive when snow accumulates, negative during melt. Spikes are storms; a long negative stretch is the melt season.
How to read it¶
- A season tracking near the bottom of the band in late winter points to a low snow year and, usually, lower spring runoff from snowmelt.
- A season leaving the band is rarer than 1 in 20 years for that date, by the model's own record.
- Values are area averages over the basin, so a basin can be normal on average while its high or low parts are not. Use the anomaly map to see where.