'History repeats itself, but in such cunning disguise that we never detect the resemblance until the damage is done.' So wrote distinguished twentieth century Chicago journalist Sydney J. HarrisSo, some will recall the severe prairie winters of the 1950s to the 1970s. During this period, Alberta experienced Canada's most severe winter storm of the 20th century. This massive storm occurred over two closely spaced events between April 17 – 20th and April 27 – 29th, 1967, which saw a monster Arctic low pressure system engulf much of Alberta.In its aftermath, around 1.75 meters of snow fell at a time when most cattle were already out in pasture. While official numbers are hard to come by, anecdotal evidence suggests thousands of cattle froze to death or suffocated under snow drifts. Entire communities were cut off from outside support, which forced both Canadian and United States armed forces to airlift food and supplies for man and beast stranded across the southern Alberta late winter wasteland.Fast forward now to November and December of last year, when Alberta saw many regional cold weather records shattered. In fact, on November 8th, 2022, Alberta achieved a special status with five communities on a list of the top 15 coldest places on the planet.Why am I taking you on this trip down memory lane and focusing on Alberta winter weather trivia?It is a well-known fact that regional wind speeds plummet and sunshine vanishes whenever large Arctic low pressure systems settle in over the Prairies. Ironically, these winter season Arctic low pressure systems give rise to peak power demand, as well as our rapidly increasing number of provincial grid stability alerts.As most Canadians know, Trudeau is pushing to phase out baseload thermal power plants by 2035 and replace them with weather-dependent Chinese-dominated wind, solar and battery technologies.With Premier Danielle Smith's Tell the Feds campaign under full steam, it is time Albertans see for themselves what weather balloon data shows regarding Western Canada's winter season meteorological trends since 1950..The annually averaged winter season (November to February) data I include are plotted as anomalies (i.e., deviation from an average baseline period) of near surface air temperature and westerly wind speeds, as well as meridional (-ve northerlies / +ve southerlies) wind speeds, starting in 1952 and extending up to the end of 2022.I include winter wind speed data together with near-surface air temperatures, as I am emphasizing that these parameters are correlated in time and am highlighting the fact that wind chill matters. In the context of Alberta facing a major review of provincial regulations specific to weather dependent power generation facilities, it is vital that Albertans grasp the inherent risks of our regional winter climate returning to the extremes of the 1950s to 1970s.While Albertans will not starve if a drought hits our agricultural sector, as we can simply import food if need be, no such option exists for our critical electricity markets if an extended drought in favourable wind speeds and clear skies were to develop during periods of extreme demand for power.Alberta's famous Chinook Effect can help make sense of these complex patterns in wind speed and air temperature.In meteorology, our Chinook Effect is generically called Foehn Winds and as shown in this illustration, is entirely dependent on the Rocky Mountains and the variable strength westerlies coming off the North Pacific. .As shown, the westerlies precipitate and warm as they ascend the western slopes. Once the westerlies break over the top of the Rockies, these warm dry air masses begin to compress and warm further as they pick up speed on their approach to ground level on the eastern side of the Rockies.This atmospheric compression creates the famous Chinook Arch, which gives rise to further warming through increasing the number of sunshine hours per day.For these reasons, we will often see Chinooks leading to rapidly rising surface temperatures in Alberta of -20 C to +20 C over a matter of hours as the westerlies pick up speed on the British Columbia side of the Rockies.In Cree, Chinook means Snow Eater, as snow accumulation is reduced during winters dominated by strong westerlies in Alberta and the Prairie region.Conversely, when the North Pacific is experiencing a cooling trend, the Chinook Effect is reduced and all these effects go into reverse and in the absence of a high-pressure blocking system over the Prairie region, Arctic low-pressure systems penetrate further into lower latitudes across Western Canada.Ironically, while wind and solar perform best when the North Pacific is undergoing a warming trend and the westerlies are strong, they perform poorly when they are not, which unfortunately is when demand for electricity reaches a maximum.This historical record shows that northerly winds dominated over southerlies from the US Southwest prior to 1991. For a brief period from 1992 to 1999, more southerly air masses from the US Southwest intruded northward into Western Canada during the winter season than northerlies, which is why annual average wintertime meridional winds trended positively during this brief period.Then starting in 2000, we once again see that winter season meridional winds in Western Canada started to become dominated by Arctic air mass intrusions as observed by the steep decline up to 2013.Note the approximate 3 degrees C decline in average winter air temperatures from 1992 to 2013. Albertans were lucky that the cooling trends observed during this 21-year period, did not go as extreme as in the 1950s to 1970s.Coincidently, the spring of 2013 is when southern Alberta witnessed a very intense winter, a delayed spring and massive flooding in June to July. The flooding occurred in large part because the June monsoon arrived at the same time the Rocky Mountain snowpack began to melt.I mark 2013 low point in all three graphs with a red star.Note how all three parameters began to move positively immediately following 2013.The yellow star marks the arrival of the most powerful El Nino warming event in the Pacific tropics since 1998 (6). In total, in 4 out of 6 years between 2014 to 2020, the Pacific tropics maintained an El Nino (warming) state, which gave rise to the warming of winter air temperatures, enhanced middle latitude westerlies, and reduced intrusions of Arctic air masses across Western Canada during its winter season following the 2013 inflection point.The challenge for Albertans and Western Canadians, is that climatic changes in the Pacific region give rise to abrupt tipping points in longer term winter climate trends across Western Canada, which are extremely difficult to predict beyond 6 months into the future.Will Western Canadians continue to embrace weather-dependent power generation with so much at stake and no ability to control or predict the direction of longer-term climate change in the Pacific, or will we be conservative and embrace a grid that is not dependent on the whims of natural climate change?
