How El Niño could impact Michigan snow, cold this winter

Also, can wooly caterpillars predict the weather?

4Warn Weather – It’s officially fall, putting us one step closer to the “f” word: “frost,” of course!

Climate data suggests that typically our first freeze happens around Oct. 25 in Metro Detroit. The earliest on record was Sept. 22, 1974, and the latest was Nov. 15, 1946.

For those wondering what it was in 2022, the earliest freeze happened on the later end: Nov. 13.

So, once the first fall freeze happens, you know what four letter word comes after that, right? It starts with an “s.”

OK, get your mind out of the gutter, I am talking about SNOW! It’s never too early to start wondering what this winter will bring. Here’s a breakdown.

El Niño and Michigan winter

We are currently in an El Niño pattern and anticipate a strong El Niño this winter.

During normal conditions in the Pacific Ocean, trade winds blow west along the equator, taking warm water from South America toward Asia. But, by definition, during El Niño the trade winds weaken and warm water is pushed back east, toward the west coast of the Americas.

When this happens, the surface temperatures of the Pacific Ocean warm closer to the U.S. -- and if it warms enough, we can see big impacts across the continental U.S.

Climate data shows that in Michigan, we experience less snow during El Niño winters 70%-80% of the time, and I am not just talking about just an inch or two. Michigan’s Lower Peninsula averages a snow deficit of 5-7 inches when we are in this type of pattern.

Now with that said, these are overall totals, so that doesn’t mean you can’t still get a whopper of a snowstorm.

In addition, the northern U.S. trends warmer than average during an El Niño winter, which we are already seeing signs of so far this fall. The Climate Prediction Center has Michigan’s overall temperatures trending above average at least through December in the latest three-month outlook.

Can wooly caterpillars predict the weather?

Now, I am a scientist, so I’m not a huge fan of rodents like the groundhog calling the shots every February. I also can’t completely buy into critters like caterpillars predicting seasons.

But, for what it is worth, weather folklore claims that the woolly bear caterpillar across the Midwest can forecast the upcoming winter. These are the fuzzy caterpillars that are usually black at both ends with a reddish brown or rust color in the middle.

According to the National Weather Service and its version of this folklore, the amount of black on the woolly bear in autumn varies proportionately with the severity of the coming winter in the locality where the caterpillar is found. Meaning: The longer the woolly bear’s black bands, the harsher the winter will be.

Similarly, more brown is associated with a milder upcoming winter.

The position of the longest dark bands supposedly indicates which part of winter will be coldest or hardest. If the head end of the caterpillar is dark, the beginning of winter will be severe. If the tail end is dark, the end of winter will be cold.

Want to see for yourself? Check your yard for a woolly bear caterpillar, which are also called woolly worms.

If you see one, snap a photo and upload it on MIPics. We can circle back around in the spring to evaluate its accuracy.

In the meantime, we will have to see how much this El Niño character can bench press … OK, OK, what I really mean is how strong El Niño will be and if it will have a direct impact on our Michigan winter.

Either way, let’s all agree not to rush fall.

About the Author:

Ashlee Baracy is an Emmy award-winning meteorologist who was born and raised in Metro Detroit. You can catch her 4Warn Weather forecasts weekday mornings, at noon and streaming on Local4+.