Why this recent snowfall won't fix southern Alberta drought conditions

The Calgary area was the literal and figurative ground zero for the bulk of last week’s snow.

According to Environment and Climate Change Canada (ECCC), the City of Calgary received just over 35 centimetres of snow over the four-day snowfall event from Tuesday until Saturday.

These totals add to what has been an unusually snowy March in Calgary. Historically, March is the snowiest month of the year in Calgary with a 30-year average of 22.7 centimetres of snow.

According to ECCC public records, as of March 25, 2024, Calgary has received 62 centimetres of snow at YYC International.

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With recent attention to the upcoming growing season as well as drought conditions – it might seem like this snowfall will make a significant difference in soil moisture, but unfortunately, the situation is more complicated than that.

This map shows snow depth throughout Alberta and parts of B.C. and Saskatchewan. (CTV News)

Local soil moisture throughout the City of Calgary will see a short-term positive impact from this recent snow – but there are many factors to consider.

If the rate of melting is too high, and/or if the ground becomes too saturated to absorb more water – a portion of that melted snow (water) will become runoff and be diverted to manmade catchments including stormwater systems.

In this regard – similar to summer rain – it is better to have multiple days of lighter, soaking rains as compared to one massive rainfall event over a short period.

The flow of our river systems is an even bigger consideration, as is the degree of drought conditions impacting southern Alberta.

Spring runoff is the greatest contributor to river water levels in our region.

Slightly higher precipitation levels in February improved the Agriculture and Agri-Food Canada Drought Monitor classification in portions of southern Alberta, however, much of the area still sits between a D2 (Severe Drought) and D4 (Exceptional Drought) rating.

The national agency notes that as of the end of February 2024, “fifty-one river basins, covering over half of the agricultural land in [Alberta] are reporting critical water shortages.”

Agriculture Canada explains low precipitation, above-seasonal temperatures and a below-average snowpack have put many rivers at “record-low levels” with “most of the province’s reservoirs” below their normal waterlines.

A drought update from Agriculture and Agri-Food Canada as of March 26, 2024. (CTV News)

Groundwater levels outside of Calgary are also experiencing steady declines and “are currently at the lowest levels ever recorded.”

Essentially, while this recent snowfall will likely improve the drought conditions, the water is entering the system too late to have a major impact on the City of Calgary.

Low water levels can create obvious challenges for agriculture, but can also pose health risks due to limited dilution (higher concentrations of unwanted materials).

In its February outlook, Agriculture and Agri-Food Canada noted that “some small municipalities in [southwestern Alberta] have had to begin to truck in water” due to higher demand compared to supply.

Feedback loops can amplify these scenarios – for example, higher temperatures often result in an increase in evaporation, further diminishing water supply.

Calgary is amid a gradual warmup, with Tuesday bringing the first daytime high above freezing since last Tuesday.

Wednesday will be the warmest day of this week and temperatures are expected to drop again by Thursday.

There is a chance of light and scattered snow over the weekend, but accumulations are expected to be minimal in Calgary.

Calgary five-day forecast for March 26-30, 2024. (CTV News)