Excerpt from Valley 101: Great Big Book of Life, a collection of Clay Thompson’s columns for The Arizona Republic. (Originally published March 4, 2004.)

Q: Why are weather forecasts still so inaccurate? We often hear a storm “just snuck in” or a predicted storm “just fell apart.” We’re talking about storms here, big things many miles high and wide, driven by lows and highs that are hundreds of miles across, steered by huge jet streams that don’t make sudden turns.We’ve got a bunch of the world’s biggest computers, thousands of monitoring stations, hundreds of trained meteorologists, and multiple competing forecasting services. So why do they so often get things wrong?

A: Hey there, Mr. Grumpypants. What’s eating you? We are living in paradise and in the very best time of the year in paradise, and I just got two nice shirts on sale, and you’re all crabby. Gee whiz.

OK, sometimes the weather forecasts are not perfect, but then what is? If things — the weather, baked goods, elections, love — always turned out just as expected, what would be the fun of that?

And I think you have sort of answered your own question. The weather is miles high and miles wide with fronts and systems and temperatures and jet streams and all that other stuff going on. In other words, there are a gazillion variables involved, even in fairly short-term forecasts. And the variables aren’t all great whopping big things. The forecast you hear or read for the Valley may not necessarily take into consideration that big asphalt parking lot down the street or a grassy park around the corner or just how the wind happens to hit your palm tree. All those things make a difference in your own personal weather.

And then there is the chaos factor, that business about how a butterfly flapping its wings in Rangoon could affect how much sunlight falls on a sleeping dog’s rear end in Mesa.

If you actually kept track, I bet you’d find that forecasts, especially short-term outlooks, are pretty much accurate. So when the unexpected does happen, it seems even more unexpected and more like a big deal than it really is.

So take off those wingtips of crabbiness, buster, and put on the flip-flops of happiness. The weather, like life, is full of surprises. That’s why it’s so interesting.