Over the past year, El Niño has been the main topic of conversation when it comes to weather. Thanks to El Niño, much of Canada enjoyed a mild, pleasant winter, which is quite typical of what accompanies this phenomenon.
El Niño Southern Oscillation (ENSO) refers to the periodic warming up of the sea surface in the south Pacific Ocean, accompanied by high pressure air in the western Pacific and low pressure in the eastern Pacific. The ENSO event of 2015 is considered to be one of the most substantial in terms of sea surface temperature anomaly and duration, rivaled only by 1997, the year that Winnipeg, Saskatoon, and Edmonton had a green, or rather brown, Christmas.
Long-range weather forecasters like El Niño events because they make their jobs easier. More specifically, these events tend to make their forecasts correct more often. Six months ago, all of the models, and thus all of the forecasters, agreed that the winter of 2015/2016 would be mild and dry.* Lo and behold, that’s exactly what happened for much of Canada. Forecasters can hold their heads high because they told us so.
While still present, this massive El Niño is gradually weakening and expected to disappear by early- to mid-summer. So the big question is, what’s next? This is where the models tend to be less in agreement.
For example, as this El Niño event peters out, there is currently some debate around whether the Oceanic Niño Index (ONI) will go negative — referred to as La Niña where sea surface temperatures are below normal — or remain neutral, sometimes referred to as La Nada.
If La Niña prevails, like El Niño, there are typical conditions that normally prevail including cold and wet weather in western Canada. If neutral (La Nada), well, we can expect the usual range of unpredictable weather. At this point, there’s about a 50- 50 chance of La Niña versus La Nada.
So where does that put the summer forecast? At this point, the lingering effects of El Niño appear to be persisting. Looking back to the El Niño of 1997, the following year, 1998, ended with the warmest spring, summer and fall on record throughout much of Canada. National record high temperatures were set for April, May, July, August, and September. July was the warmest month since records have been kept. Combined with the heat, 1998 was also one of the driest years on record.
This year, temperatures across the prairies in May and June are expected to be above normal, particularly as you move west into Alberta. For areas that have been dry, this does not bode well as warmer temperatures mean thirstier crops and the possibility of drought. At this point, there is only a slight chance that anywhere in the west will receive above average rainfall. For areas that have been too wet over the past few years, this probably comes as welcome news.
An early spring has meant early seeding in much of the prairies. But germination, crop establishment, and yield will depend on getting adequate moisture at the right times, particularly in areas with little soil moisture reserves.
Also as I recall, in 1998, earlyseeded crops, rapid crop development, and timely rains resulted in some of the best crops in years. FF farm life
By Andrew Nadler | Agricultural meterorologist
* Worth mentioning that all but one forecast called for a mild and dry winter in western Canada. The Old Farmer’s Almanac predicted cold and snowy for the prairie provinces.