Ahh..... fall in Michigan. Cozy sweaters, days as crisp as our apples, chilly breezes and frosty pumpkins. Wait, whaaaat?
We were almost alone at the cider mill I visited this weekend. The workers told me it was just too hot. Schools are closing early in metro Detroit because some classrooms feel like a furnace in this heat wave. People are searching for open swimming pools while fall coats and Halloween costumes hang untouched on racks.
- September could be among the warmest ever in metro Detroit history
- A powerful cold front will hit metro Detroit next week, but it won't last
- Why metro Detroit's fall weather outlook may surprise you
And you can call it a heat wave for sure. Monday was the 5th consecutive day with high temperatures within a degree of 90 in metro Detroit, and the high humidity has made it feel even hotter, and even more like July.
So, first of all, it isn't over. It will be very hot again Tuesday before cooling starts Wednesday and it gets cool late in the week. (See our latest Detroit weather forecasts.)
But is global warming making an appearance in metro Detroit this fall? The short answer is yes, but the longer answer is also easy to understand.
Climate scientists like to talk about "attribution," but the climate, which is the weather over a long period of time, is complicated. Consider a big, beefy guy on steroids (hypothetically, of course, since they're not healthy) who smacks your eye and gives you a black eye. That's pretty simple attribution, a cause and effect sort of thing. But if that same guy plays baseball (I know, it could never happen) and hits a home run, was it the steroids that caused the home run? No, the steroids didn't cause the home run, but they made it more likely that he'd get the ball over the fence because his muscles are bigger. Now, our slugger could still strike out, just like we can still get unusually cold weather even in a warming climate. But you would expect his power stats to go up and when they do, you aren't surprised. That's why climate scientists aren't at all surprised by our "wacky" heat wave.
When you hear our average temperatures have gone up about 1.5 degrees Fahrenheit, it may not seem like a big deal. But a small change in average temperatures has a large effect on the frequency of extreme heat like we're seeing now in southeast Michigan.
Of course, natural variability plays a part in extreme weather events. Heat waves and cold snaps have happened for a long time. But climate change has shifted the odds, making heat waves more frequent, more likely and more intense.
Consider record highs and lows. Back in the 1950s, in Detroit we had roughly an even balance between days with record highs and days when we saw a record low. Nationally, over the past decade, the number of record highs has been more than twice the number of record lows. This year in Detroit has been even more pronounced. Including yesterday, we've had 8 days on which we either tied or broke a record high in 2017. The number of days when we've seen a record low: 0, zilcho. Even in a warming climate, new record lows will occur, though fewer in number, due to natural variation even as the climate warms.
And yes, it did get unusually cool around here in late August and early September, but even so, the three month period of June, July and August still ended up with slightly above average temperatures in Detroit. And that's on the heels of the summer of 2016, which was the hottest ever recorded in metro Detroit.
The three warmest summers we've ever had in metro Detroit have all come since 2005.
After Major League Baseball started testing for steroids, home run numbers went down. Increasing greenhouse gases in our atmosphere will take longer to reduce than drugs in a hulk's bloodstream, but it would certainly help to reduce the sizzle. Climate change is not all natural, but let's wait until the weather cools off a little to talk about that.
