When The Big Thaw Hits

As we watch the sun disappear behind the clouds today, we have to consider emergency preparedness and what happens when a rapid thaw occurs after there is a lot of snow.

There are two big questions:

  • What does this mean to me; I mean, I’m in an office, right?
  • What do I have to do to prepare, since, ok, I get it now?

So what does it mean? Rapid rises in temperature, in the winter anyway, result from weather systems. If you are a weather geek, you’ll know terms like frontal boundaries, occluded fronts, moisture pumps, omega blocks, and this years favourite scary term, “The polar vortex”. Huh? Ok, sudden warm weather means rain and melting. Usually a lot of it. We are currently forecast to get 30mm of rain, but we’re also going to get almost that in melt. So, Randall, that’s only 6cm of water. Who cares? Well, there are a few big problems for you. Let’s start at home.

The most important thing to do when you get home tonight (or now if you are home) is to clear your storm drains. If you don’t, water will simply flood the streets. But 60mm translates to a whole lot more because all that water in your yard has to go somewhere. We’re now up to triple that on the road, and that’s probably above your front-end air dam on your car. But wait, there’s more. The water is also going to flood into the buried power transformers, which do not like getting wet. Oh, and their drains are probably all frozen too. Worse, the salt on your street is going to mix with the water to make a really good conductor, so you need to make sure to avoid going near ground transformers during the storms and until the water drains off.

So the impact at work is, expect power failures and surges. There will be flooding on the roads, so you might want to consider public transit. Do you park in an underground garage? Did you remember to test your UPS batteries?

At home, clean those drains, have candles, and stay away from transformers. Monitor the situation and if you see water pooling up against the side of the house, get out the shovels. In fact, go out now and look for low spots in the snow. And if you’re me, check the UPS batteries at home also. They’ve had quite the workout this season.

You should also monitor the situation as it happens. The Weather Network has published a severe warning here:


You can also read my interview with The Richmond Hill Liberal by Kim Zarzour here:


Noah’s Flood

What will make things really nasty is the potential for the following: The high snow banks can temporarily keep some of the water in large pools. Eventually, the snow/ice mix will melt and have a catastrophic failure. This means a rapid break, rather like a dam bursting is possible in places. It is absolutely crucial that you and your children stay away from flowing water and avoid being below these dams. Safety first. For example, avoid the Upper Mill Pond park area during and immediately after this event.

For Geeks Only

If you are really interested in doing the math (If your name is Sheldon, for instance, and are reading this), take the ground topography of the area for your volume calculation. Assume a 1:3 road to property ratio, and that the weeping tiles are frozen solid so have no absorption at this time of year so do not factor into capacity. If you want to make things deeper, assume that all snow/ice on roofs, roughly 1:1 with the roads, are going to completely melt off and not pool on the properly, and that these will translate from 15cm snow/ice mix to 5cm of water (it would roughly be 1.5cm of water if it was just snow).  As a SWAG, this results in roughly 200-300cm of water that could pool without proper road drainage. But don’t hold me to these numbers. They are for planning guidance only. The number could be vary by a magnitude either way.

3 thoughts on “When The Big Thaw Hits”

  1. Around noon today, our town came by and unburied the storm drains. Special thanks to our councillor, David West, for looking into the matter of us.

  2. Breaking news: We’re having Thunder Snow right now. But Environment Canada changed the expected mix of precipitation a little more to the snow side. Good news from a management standpoint.

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