Rainfall, flooding alerts for areas of Dehcho region starting tomorrow

The South Nahanni River flows through Nahanni National Park Reserve. (Photo courtesy of NWT Tourism)

A storm system expected in the southern part of the Mackenzie Mountains between tomorrow and Friday could see over one month’s worth of rain could potentially fall within one day.

The community of Nahanni Butte – used to wildfire warnings this year — should be aware of this system, monitor conditions closely, and assess any risks to their community based on those conditions.

Environment and Climate Change Canada issued a warning today, forecasting “with high confidence” a large rainfall event — 60 to 80 millimetres and more — with the heaviest rainfall to start falling tomorrow afternoon, lasting until the Friday morning.

While it’s hard to tell at present, forecasts suggest the South Nahanni River basin could see very significant rainfall.

A rise in water level of over one metre is possible if the rainfall is concentrated in one basin.

This could impact people on the land.

Rivers flowing into the Liard and Mackenzie rivers from the Mackenzie Mountains – such as the South Nahanni River, North Nahanni River, Root River, and Redstone River – are strongly affected by rainfall in the Mackenzie Mountains.

This level of rainfall could mean rapid rises in water levels and flow along these rivers.

The rise in water levels will depend on where the precipitation falls.

If heavy rainfall falls within the South Nahanni Basin as forecast, there is the possibility of rapid rises in water levels and flow on the South Nahanni River and in the community of Nahanni Butte.

This level of rainfall in a short period also has the potential to cause challenges for infrastructure like roads and drainage systems.

It could also pose safety issues for those planning to be out on-the-land this week.