By now we’re all painfully aware that there is a serious lack of snow on the North Shore Mountains. But how does this compare to previous low snowfall season? And what might it mean for the Spring and Summer? Here’s a brief look at where we stand now and what we might be in for:
- The North Shore snowpack is 0-10% of normal for this time of year (summer water shortage?)
- The Pacific Decadal Oscillation (PDO) is strongly positive ( a shift from a cooler previous 8-10 years)
- El Nino has finally arrived after teasing us for many months
- The short and long range weather outlooks look warm – meaning no snow on the horizon
- El Nino in the summer is associated with more lightning in Western North America (fire alert!)
Now let’s look at the details…
Well, This is really incredible! The measured snowpack depth on March 1 on Grouse Mountain and Dog Mountain (Seymour), both at around 1000-1100 m, was zero centimetres. This was the first time that there was no measured snow on the ground at this time of year in well over 40 years of records. The normal snow depth for March 1 is around 230 cm. If you climb up toward the summits of the mountains (roughly 1400 m) there is probably 40-60 cm of snow, but this is still only 10-15% of the normal snowpack. Very grim!
Now, even if we see a modest return of winter for the next few weeks, the snowpack will not build significantly. We typically see a growing snowpack up until around April 1, but it does not grow very dramatically – roughly 8-10%. Also, there is a big difference in snow density and snow-water equivalency from an early season snowpack to a spring snowpack. A 200 cm deep snowpack in January would hold roughly 700 mm of water, and the same snow depth in May holds 1000 mm of water. So, if we do get some fresh snow it will not hold much water compared to a dense, well-settled spring snowpack. Also, the average temperature and the strength of the sun at this time of year are such that the fresh snow would not last long. Any new snow that falls would probably melt very quickly. So in summary, winter really is done around here!
What will this lack of snow mean for our summer water supply? The reservoirs are typically fed by snow melt well into the summer. This year there could be no snow melt at all after April. That must have some serious implications. I think it will require very good conservation and management, from both Water Services and the public. We could see watering restrictions take effect much earlier than usual this summer. Maybe this will lead to a local drought.
What about forest fires? The last winter season where we saw very low snowpack depths was in 2005. Oddly enough, this was considered to be a very slow forest fire season provincially. It came on the heels of two of the busiest fire seasons on record but did not amount to much. The only real notable local fire was the Burns Bog fire in September 2005. This was a 200 hectare fire in Delta that significantly impacted local air quality. It’s always difficult to predict how a forest fire season might turn out. It depends greatly on the weather, particularly the amount of lightning. Last summer was very warm and dry but there was almost no lightning in the Vancouver area, which led to very few forest fires. Of interest though… El Nino summers are associated with increased lightning activity and strikes in Western North America. Potentially bad news! Let’s take a look at what the current status of the El Nino – Southern Oscillation (ENSO) is.
Our summer outlook will depend greatly on the weather. Will we see a wet and cool spring that will allow local officials to top up the reservoirs and soak the ground? Or, will we see continued warm and dry weather? In the short term it looks strongly like we will see continued warm and relatively dry weather (see images below). And now it also looks like the much talked about 2015 El Nino has finally kicked into gear. Climatologists have been forecasting a weak El Nino event for quite a while, but the pattern only fully developed in February. The missing ingredient was the trade winds, which were reluctant to sync with the warm ocean waters in the Eastern Pacific. This El Nino event could be different than recent events due to the fact that it could be joining forces with a very strong (positive) Pacific Decadal Oscillation (PDO). If the PDO stays strong and this El Nino event lasts a long as it’s predicted to last (up to 2 years), then we could see continued mild weather well into spring. However, the effects of El Nino are still somewhat uncertain and are associated more with winter weather in our region. Maybe it will be a wet summer? The bad news is that if the El Nino and positive PDO do last through next winter then we’re probably looking at another lousy local ski season.
Here’s a good read about the evolution of this year’s El Nino.