Why are meteorologists’ forecasts so different?

Weather Blog

It’s a question I hear A LOT. It usually goes something like, “Hey, you guys have me in 2-4″, but channel 100 has 3-6″ and channel 101 has 4-8″. Can’t you guys get it right”?

Welcome to the world of practicing meteorology. It’s an inexact science full of errors, imperfections and frustration. Because it’s inexact, there’s an inherent human element to a forecast. A big one. Predicting the weather, despite enormous advances in modern technology, is very much a human business. Opinions, experience, bias & effort are all factors that make a forecast, well…varied.

Put 10 meteorologists in a room. All 10 look at the same data, the same information. Yet all 10 will likely come up with a slightly different outcome when it comes to a forecast. How come? Maybe a few haven’t been doing it very long and are inexperienced. Maybe a few recognized a quirk in the pattern that they’d see before and influenced their forecast. Maybe a few have a go-to model and they lean toward that one. Regardless, there’s an infinite series of decisions and calculations occurring in the human mind long after the infinite series of decisions and calculations the models had come up with. And that, my friends, is why forecasting something like a snowstorm is akin to the snowflakes themselves. No two are the same.

This isn’t unique to meteorology, either. Say your shoulder hurts (probably from shoveling tonight’s snow). You go see a doctor, who tells you it’s probably just inflammation. Rest, and you’ll be fine. Another tells you it could be a rotator cuff tear and sends you off for an MRI. Yet another is concerned you have serious damage and recommends surgery. We understand that there is an element of relativity when it comes to the expertise of practicing medicine. We shop around for a doctor we think gets it right more than they get it wrong. But at the end of the day, we recognize it’s not a perfect science, subject rather to the opinions of highly skilled but still human doctors.

Let me use tonight’s system as an example. All meteorologists are looking at the same models. Those models, as amazingly skilled as they are, will never be completely right. They vary from model to model, like this…

The Euro suggest 2.6″ of snow in Rochester
While the GFS suggest we don’t even see 1″

It’s gets worse. Many times, the same model will flip flop from one run to another, like this…

Uh-oh! Nearly 8″ of heavy, wet snow.
And…it’s cut in half.

Forecasting isn’t as simple as looking at one of these maps and repeating what it says on TV. Maybe one day, but we’re a long way from that point. It takes careful interpretation looking at details throughout the entire vertical expanse of our atmosphere and years of experience to properly “read” something that truly isn’t designed to be read at face value. So I may come up with 4″, while someone else equally as adept at forecasting could come up with 8″. We’re looking at the same stuff, but our brains are wired to output a different result.

This is why I often tell people to shop around for their weather information. Find a source that you feel gets it right more than others, and go with them. And don’t be afraid to reassess those decisions in time. Hey, they say variety is the spice of life, right? After reading this, pay attention the next time snow is in the forecast. There will be plenty of spice to go around.

Chief Meteorologist Eric Snitil

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