December Issue #1
The Consequences of Snow Drought
It’s officially December, which means you’ll be hearing the same Mariah Carey and Michael Bublé songs any time you step into a store. While this month might be full of twinkling lights, Trader Joe’s Cedar Balsam candles, and sugar cookies, there’s one key winter detail the Western US started off in the red—with snow.
This month we’ll be talking about all things winter storm cycles, the lack of them, and the consequences of a low snow year on water supplies and fire risk—if one of you dear readers has any expertise on this subject, let us know. For I am learning as I write each week.
Understanding the system
A quick reminder of the water cycle: the sun heats water into vapor that forms clouds, cools, and falls as rain or snow...then the cycle repeats. Geography, weather patterns, the timing of storms, and temperature all play a key role in how much water eventually reaches reservoirs, farms, fields, and homes that rely on these supplies.
Snow drought—what is it and what are its implications
Dan McEvoy, regional climatologist at the Western Regional Climate Center and the Desert Research Institute, explains that drought is a snowpack deficit. In other words, less snow than there should be for a given time and place. Now, there are two types of snow drought: dry snow drought, below-normal cold-season precipitation, and warm snow drought, which is the lack of snow accumulation despite close-to-normal precipitation (caused by warm temperatures and resulting in rain rather than snow) leading to unusually early snowmelt.
The West’s water infrastructure relies heavily on snowpack* (how much snow is on the ground in March or April, minus the melt, for the year). Snow drought reduces the amount of available water for spring and summer snow melt. This can then reduce or change the timing of streamflow and reduces soil moisture..which as you guessed can impact water storage, irrigation, fisheries, vegetation, municipal water supplies, and wildfire. In next week’s edition, we’ll explore the impacts on water storage and irrigation.
*It was built assuming there would be a natural reservoir of snow in the mountains
