Some people heard a few claps of thunder this weekend with the rain. If you follow the old folklore, thunder in the winter means snow is coming.
Though it appears to change depending on who tells it. Sometimes I’ve heard it as seven days, 10 days or 14 days after thunder in the winter time that snow is coming. The general folklore though goes by 10 days from getting winter thunder you should get snow.
Some folklore can actually be based on a bit of science. This one isn’t entirely a crazy idea if you think of the weather pattern that leads to thunder or thunderstorms in the winter. You usually have a strong cold front that is bringing in a colder pattern after a warm-up. So on its face, it kind of makes sense that it would turn colder after we get a strong cold front with thunderstorms in the winter. Though as you know, getting cold is only half the equation for snow in the Carolinas.
What the data says
So ever since hearing this, I always like to look back at the actual data to see how often it works out. So here’s the bad news. It only works about 10-20% of the time.
In the past 6 winters including this winter, I looked for all the time’s that thunder was reported at the airport. Yes, I’m sure someone hears thunder in other spots, but we have 24/7 365 reliable weather data that goes back 138 years at the airport.
So I used the airport data for quality control. In the past 6 winters, I looked for when thunder was reported anytime of the day in the winter months of December, January and February. I found 30 sperate days where thunder was reported. Of those 30 days of thunder, only 3 times for sure did we have snow within 10 days. This year our snow fell right on the 10-11 day threshold, so I counted it. That means just in the past 6 winters this folklore only worked out 13% of the time.
Not to burst anyone’s dreams but in general, the whole thunder in winter then snow within 10 days thing. Just doesn’t stand up to the data. It’s fun to dream but in reality, it just doesn't work out the way the saying goes.
