I don’t know about you, but I was glad to see the tail end of last week. I can’t re­mem­ber see­ing such a va­ri­ety of weather. Ad­vi­sories, watches and warn­ings were in place for snow, rain, freez­ing driz­zle, freez­ing rain, blow­ing snow, Wreck­house winds and Suetes winds…all at the same time! These things did all take place…and more. The more is thun­der­storms. The re­ports started to come in around noon on Wed­nes­day– first from the south shore re­gion of Nova Sco­tia, then from the Val­ley and be­fore the end of the day, pock­ets of thun­der­show­ers had popped up ev­ery­where…on the warm side of the sys­tem of course. At the height of the storm, a reader re­minded me about what Grandma would say. If Grandma heard thun­der in the win­ter, she be­lieved there would be a snow storm 7 days later. Can there be any truth to this?

Per­haps a lit­tle grain of truth. Thun­der in the win­ter comes when cer­tain frontal bound­aries in­ter­act and that might give us a glimpse at what’s to come.

Cold air and low-pres­sure sys­tems from the north, dis­plac­ing warm air and high pres­sure in the south, form an un­sta­ble at­mos­phere and the ver­ti­cal lift along the frontal line is enough to trig­ger thun­der­storms. That kind of in­sta­bil­ity is cre­ated as a cold front pushes in. The cold front opens the arc­tic pipe­line ahead of a high pres­sure sys­tem. Cold win­ter highs can sit for 3 days or more. Be­hind ev­ery high there’s an­other low. It might take a day or two to build into the re­gion.

Now we’re close to 6 days. That next, moist weather sys­tem could con­ceiv­ably bring snow.

The “seven days” thing should not be taken lit­er­ally but in my ex­pe­ri­ence, it’s not usu­ally too far off.

What do I think? Well, I be­lieve that win­ter thun­der does tell us a bit more about how the weather might be­have than, say, a ground­hog that sniffs its way out of a bur­row once a year.

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