Opposite pattern to last year

I wouldn’t go as far as to say that panic is setting in over the weather, but from some of the conversations I am hearing, it’s not too far off. Personally, I think it’s a little too early to hit the panic button.

As I pointed out in an article a couple of weeks ago, the average date for the snow to be gone across southern Manitoba is between April 5 and 12, a few days earlier over southwestern regions and a few days later over central regions. What we need to remember about averages is just that: they are averages. In the world of climate and weather we rarely see average conditions; something is usually above average or below average. It only makes sense: if we have a year when the snow melts two weeks early, there is usually going to be a year when it will melt two weeks later.

The interesting thing, at least for our part of the world, is how often an extreme above- or below-average event is closely followed by the opposite event. For example, the coldest average maximum monthly temperature for April recorded in Winnipeg occurred in 1950 (+2.1 C). The warmest average maximum monthly temperature for April recorded in Winnipeg occurred just two years later, in 1952 (+16.8 C). So it should not seem that unusual for us to see a record-early spring followed by a late spring. Will it be a record-late spring? You need to read on.

Whither global warming?

When we see cold weather like this, the talk naturally turns to climate change and global warming and the critics start coming out to stir the pot, asking, Where is the global warming now? Shouldn’t we always be seeing warmer springs? The answer is, No, we shouldn’t. As I already pointed out, we look at weather or climate using averages and these averages are made up of above-average and below-average temperatures. We always have seen and will continue to see temperatures that are above and below the average. When we discuss global warming what we are looking at are the numbers of times temperatures are above average compared to below average. We are also looking at how much above or below the average we are seeing.

Globally we are seeing more temperatures coming in above average than below average and the amount these temperatures are above average is exceeding the range of below-average temperatures. Just looking at my own weather station data, which is in a rural setting and routinely records temperatures much colder than the closest city, Winnipeg, over the last 14 years I’ve recorded 105 months above the Winnipeg average and 63 months below the Winnipeg average.

So, let’s look at this April so far. We’ve been well below average in temperature and these conditions look to last for at least a couple more weeks; check out the forecast for more information. These cold temperatures, combined with a deep snow pack, mean we will have a late spring melt this year. Will it be a record-late melt? I doubt it, unless we see a record-big snowstorm move in sometime in the next couple of weeks. Does this late melt mean there is no such thing as global warming? No. If we want to play the average game again, last year we saw a record-early snow melt and start to spring. To even this out, we need to see a record-late year. For that to happen, the snow would have to stick around until May 1 or so. That doesn’t mean the snow melts, disappears, and then we see snow again. That doesn’t count. We have seen May snowstorms more often than we care to admit. To beat the record, our current snow cover has to stick around right through to the start of May.

The other big question regarding the weather is, Why? Why are we seeing this early spring cold snap? In a nutshell, back in March, the atmospheric pattern across North America started to block up with a very strong area of high pressure forming over Greenland. This allowed, or helped to form, a large trough of low pressure across much of North America. This is almost the exact opposite pattern to what occurred last year, so it makes sense that instead of bringing warm, dry conditions we are seeing cold, wet ones. Last year’s early-spring blocking pattern waxed and waned in strength for about two months before fading away. While this year’s block formed a little earlier than last year, let’s hope that it doesn’t last quite as long!

About the author

Co-operator contributor

Daniel Bezte

Daniel Bezte is a teacher by profession with a BA (Hon.) in geography, specializing in climatology, from the U of W. He operates a computerized weather station near Birds Hill Park.



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