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Manitoba just came out of its wettest September in 100 years

Summer-like humidity led to a couple of record-warm overnights

With my new earlier deadline it’s just a bit too early for me to do my look back at the previous month’s weather, but I think it is pretty obvious what this week’s weather topic should be: rain.

As I work away on this article late trying to beat my morning deadline, it’s raining once again. So far at my weather station I have received 118 mm of rain this month, and while this might seem like a lot of rain, there have been places across agricultural Manitoba which have seen a whole lot more than this. For a few farmers, this rain is a blessing and they are happy, but for most, even though it was needed, it just couldn’t have come at a worse time.

September is usually not known for being a wet month, with average rainfall amounts running in the 40-60 mm range. While some regions have been dealing with drought conditions ranging all the way back to May, and have had to declare agricultural emergencies due to poor growing conditions brought on by the dry weather, this rain is doing little to help this situation right now — but as usual, it all depends on the timing. If your crop is off, then the rain is welcome, even though it might be an inconvenience. If you’re still working on getting the crop off, well, this rain is more than an inconvenience, it just might break the year. I don’t pretend to know how difficult it might be, but I can get a bit of an idea by extrapolating just how hard it’s been to wrap up my gardens in the fall when it is wet — everything takes way longer, it’s messy, and some things just can’t get done no matter how much you want to do them.

Now, back to the wet September. If we look back at the numbers for previous Septembers, some regions only have to go back to last September to see similar rainfall amounts. With another potentially wet system moving through before the end of the month, it looks like most places will end up much wetter than last September. Digging back further, the next wettest September was back in 2004, but it looks like most areas will beat out that year. I decided to look back at the wettest Septembers for the three main recording stations that I use to represent agricultural Manitoba: Winnipeg for central and eastern regions, Brandon for western regions, and Dauphin for the northwestern regions. Table 1 shows what I found digging back through the records.

Looking at that data, you can see the Brandon region has already broken its record for the wettest September on record, with the Winnipeg region having a shot, depending on just how wet last weekend’s storm system ends up being. The nature of the wet weather, as I stated earlier, has behaved more like a winter-type pattern and has resulted in the heaviest rainfall staying to the south and east of the Dauphin region.

For some areas of Manitoba, the total rainfall amounts are much higher than this, thanks to the unusually warm and humid air that invaded most of Manitoba during the week of Sept. 16-22. While warm weather is not that unusual in September, and we did see a few daytime record highs broken, what was unusual was the accompanying humidity. The summer-like humidity led to a couple of very warm overnights that broke several records. All this moisture was eventually tapped into by an area of low pressure that led to some intense thunderstorms, which brought some extreme rainfall — not just for September, but for any month. The table at the top of the page shows some of the largest rainfall amounts that fell during the period of Sept. 19-22.

Why have I been referring to this weather pattern as a winter-like pattern without the really cold air? Well, two of the three rain systems that impacted our region over the last week have been almost textbook examples of Colorado lows, something we usually only see in the winter. The other system behaved very much like an Alberta clipper, which, once again, we usually only see in the winter. Now, the question that is nagging at the back of my mind is: will this pattern continue into October and November, bringing us what just might be a snowy start to this winter? After all, the cold air will eventually work its way southward. I guess we’ll just have to wait until the next issue to see if any of the weather models change their forecasts for the upcoming months.

About the author

Co-operator contributor

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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