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Warm Start To Summer To Continue

It seems like it’s time to revisit my prediction for a hot, dry summer! I have received a fair number of emails and comments pointing out how far off I was with my prediction for a hot, dry summer… although, I did hear someone say, and I have to admit it was a youngster pointing this out, that maybe everyone should wait before I am strung up with piano wire because according to their grandpa, summer was barely just beginning and there was a lot of weather still to come.

I have to admit, my earlier prediction of a hot, dry spring and summer vanished fairly quickly during May, but my initial feeling that we would see a warm summer never did disappear. Unfortunately, it is getting to be a little late to satisfy some of my friends that were hoping for one of those hot, dry summers from years ago so that their kids could experience what it is like. It was that notion that got me thinking about how different weather cycles can influence how a person thinks and remembers not just the weather, but their entire childhood. Just think, how many kids have grown up over the last 10 years who have no idea what a drought or real intense heat wave is?

Well, I don’t really want to get into that discussion just right now, instead I would like to try one more attempt at looking ahead at what the rest of the summer might hold in store for us.

In this regard I am going to hang everything on the changing conditions over the Pacific Ocean. The Pacific Ocean, which has been in a fairly strong El Nińo over the winter, has quickly crossed the threshold into La Nińa conditions.

Sea surface temperatures (SSTs) over the tropical Eastern Pacific in the area 5 degrees N -5 degrees S, 120 degrees W -170 degrees W fell to 0.8 C below average by July 12, according to NOAA. La Nińa conditions are defined as occurring when the average temperature reaches 0.5 C below average, so conditions are well into the territory of a weak La Nińa event.

La Nińa conditions must be present for several months before this will be officially classified as a La Nińa event, but according to J. Masters at NOAA it is highly likely that a full-fledged La Nińa event lasting at least eight months has arrived.

This year started out with a strong El Nińo and so it may seem surprising that we have transitioned to La Nińa so quickly. However, historically, about 35 to 40 per cent of El Nińo events are followed by a La Nińa within the same year. Given the current trends, it looks like the current La Nińa will cross the threshold needed to be defined as “moderate” in strength (at least 1.0 C below average in the equatorial Eastern Pacific) by September, according to Dr. Masters.

While La Nińa conditions have traditionally brought more hurricanes across the Atlantic, over our region there does not seem to be major impacts weather-wise. As I pointed out earlier in the article, I still feel that this transition in the weather pattern will define our summer weather.

My initial summer forecast was based on the weather pattern that controlled our fall and winter weather continuing into the spring and summer. I basically thought we were coming to the end of our wet period. Instead, we ended up in a transition period during May and June which brought us plenty of rain and believe it or not, near-to above-average temperatures.

July has seen a continuation of these mild temperatures. Even though we have been in a pattern that over previous years would have brought fairly cool temperatures into our region, overall, most areas have seen temperatures during the first half of July running 1 to 2 C above average.

Now back to La Nińa. The last time we saw a rapid switch from El Nińo to La Nińa conditions was in 1998. During that year, July ended up being about 1.0 C above average while August and September ended up being very warm, with temperatures running over 3 C above average. Precipitation was also well below average during that period in 1998.

Will we see the same La Nińa summer as we did in 1998? As I am famous for saying – I guess only time will tell, but it sure would feel nice if I was able to pull off at least a little bit of a save for my long-range summer forecast.

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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