Unseasonably warm weather has brought an early onset to snowmelt in the Northwest, but due to prolonged droughts and dry forecasts it’s doubtful the region needs to worry about flooding this spring.
“Regionally the snowpack is below normal…in general it’s looking like it’s been pretty dry up in the Northwest part of the province and we’ve even come down in our [estimates] by about 10 per cent — so we’re sitting around 75 per cent [of normal] for the Skeena-Nass region,” says hydrologist Dave Campbell, head of the River Forecast Centre.
Last year record temperatures caused an early snowmelt in late April, and from late August the area plunged into months-long extreme (Level 4) drought conditions. On multiple occasions Skeena flow volumes fell below all-time records since data was first kept in 1928.
Currently Skeena flow rates at the Usk gauge are registering about 350 cubic-metres per second, only slightly higher than the seasonal norm of just under 200 cubic-metres per second.
In coastal areas, a warm March led to modest increases in streamflows, which still remain well below normal for this time of year.
“The risks of flooding is still there, but it’s shifting more to concerns of if we get any unexpected heavy rainfall patterns,” Campbell says. “That’s the only thing that would really drive any flood risks because from the snowmelt side of things it’s looking pretty modest in terms of seasonal risk.”
Environment Canada data shows a high-pressure system dominated the region in March, delivering just 30 mm of rain in the Terrace area —less than one-third of the normal 92 mm typical for the month since 1913.
Regionally, weather forecasts for the next three months show a 90 per cent probability of temperatures exceeding seasonal norms in the Northwest. As for rain, Environment Canada meteorologist Armel Castellan warns precipitation forecasts are much more difficult to gauge.
“Persistence would say we can expect relatively dry conditions…it’s a mix between a neutral and a below-normal precipitation amount,” says Castellan. “It’s only when we get to early May that things look a little wetter, but that’s a month away so it’s very tough to hang your hat on that.”
Heading into the winter months last year, record low levels in many Skeena tributaries were identified by the SkeenaWild Conservation Trust as too shallow for salmon to reach their spawning grounds. As levels improved slightly there was still concern the eggs may freeze.
SkeenaWild’s executive director, Greg Knox, says stakeholders won’t know for certain how the salmon fared through the winter until planned studies are carried out in May and June.
“The weather wasn’t too cold, which is sometimes helpful,” Knox says. “The warmer water helps them develop faster and hatch out of the gravel sooner. The challenge of course is now going into the spring where we have almost a continuation of the drought we had last summer.”