Does winter thunder really mean snow is on the way?

Did you wake up this morning at 3 a.m. to the sound of thunder and flash of lightning? Did you immediately get excited and wake up the whole house screaming, "it's going to snow in a week, it's going to snow in a week?!?" Yeah, me neither, but I did immediately pop out of bed to check computer models to see if there was any hint of snow in the near future for the Augusta area. Why?

Well, the real reason was rooted in curiosity more (way more) than scientific truth, but there is a popular bit of weather lore stating that thunder in winter means it will snow within one week. This is most likely true, I suppose, in places like North Dakota or Chicago or Pittsburgh, since it snows about once a week there anyway, but what about in Georgia or Alabama or South Carolina? Let's explore.

First, we must understand what makes lightning, the cause of thunder, more common in summer than winter. The simple answer is: heat. Heat rises, and the hotter the air, relative to the air above it, the faster it rises and the more likely thunderstorms are. In summer, there is plenty of heat and thunderstorms are quite common in our part of the world, but in winter, the atmosphere is much more stable, and storms are much more rare, which is probably where the speculation about lightning's relationship to snow originates.

So why a week and not a day, or twelve hours? After all, most thunderstorms, practically all, in winter, are caused by cold fronts, so wouldn't the snow occur the day after thunderstorms when the coldest weather arrives? Great logic, but as Lee Corso would say, not so fast! The trouble with this line of reasoning is that the air behind an arctic cold front is cold and VERY DRY, making any form of precipitation nearly impossible for at least a few days.

This is where the "within one week" part comes into play. I'm not saying that I immediately revise my 7 day forecast at the sound of thunder in January, but storm systems this time of year do arrive with an average frequency of about one to two times a week, so if the next storm system arrives before the air mass has time to thaw out from the thunderstorm producing cold front, snow would certainly be a possibility, say 4 to 7 days after the storms occurred.

In conclusion, there is no way thunder in winter can literally mean it will snow within one week. No scientist with an credibility would try to tell you that, but with computer models currently flirting with the idea of the white stuff almost exactly a week after this morning's storms, I must admit that this snow lover will be checking the computer models a little more frequently for the next week or so.