Rain has a varied impact on snow depending on the depth of the snowpack. Shallow snow is usually obliterated by rain, while deep snowpacks can sometimes absorb some of the rainfall.
The Impact of Rain on Snow:
| Snow Condition | Impact of Rain |
|---|---|
| Shallow Snow | Obliterated; the rain completely melts and washes away the shallow snow. |
| Deep Snowpack | Absorption: the deep snowpack can absorb some of the rainfall. This water can freeze again when temperatures drop. |
Understanding the Process:
- Shallow Snow: When rain falls on a thin layer of snow, the warm temperature of the rain quickly melts it away. This can lead to bare ground or muddy conditions.
- Deep Snowpack: In a deep snowpack, the situation is more complex. Instead of immediately melting the snow, the water from the rain can percolate down through the snowpack. Some of this water might be absorbed by the snow itself, leading to an increase in the overall water content of the snowpack.
Important Exception:
- According to the reference, snow melt is typically not part of the runoff process in deeper snowpacks, except during very exceptional events like major flood events or large storms.
Practical Example
- Example: Imagine a light snowfall that is only a few inches deep. A rainstorm on top of it will likely melt it completely. On the other hand, a region with a deep snowpack of several feet might absorb a rainstorm initially, without creating a massive melt-off.
In summary, rain's impact on snow depends heavily on the depth of the snowpack, with shallow snow being easily melted and deeper snow potentially absorbing some of the rain. Snow melt is typically not part of the runoff process in deep snowpacks unless in exceptional circumstances.
