Wednesday, November 27, 2013

Whether or not to believe the forecasted weather

I cringe when I see a “10 day forecast” on any sort of weather channel or website. Why? Well, the fact is that no one can accurately predict the weather 10 days from now. The key word is “accurately.”

Oh, weather forecasters can get close, sometimes, but often it is a guessing game on trends from the past and what might happen based on current conditions.

I worked for many years in the TV news business. I had the chance to get to know several meteorologists. By and large, they were really good folks who honestly wanted to help people.

One day, I asked one of them the following question, “Just how sure are you that it is going to rain two days from now?”

His response? He said, “Honestly, we have about a 50% chance of getting tomorrow’s weather right. Each day after that, our chance of being right is cut in half. There are just too many variables that can impact the weather.”

When he first told me this, I was a bit shocked. Before then, I really believed it when I was told it was going to rain seven days from now.

I was thinking about this subject recently and decided to do a little experiment. I went to the National Weather Service website and tracked their predictions for a certain day over the course of a week.

I was surprised how close they got, but even then, there were a number of changes.

The day in question was Wednesday, November 27, 2013. I started tracking the forecast when it first showed up on the National Weather Service’s 7 day forecast.

During those seven days, here are the differences between the forecasts:

The high temperature varied from a high of 38 to a high of 49.

The chance of rain varied from 50% to 90%.

The amount of rain varied from a “trace” to half-an-inch.

The winds varied from 7 mph to 32 mph.

The time the showers were “mainly” supposed to happen varied from 10 AM to 4 PM.

To be fair, they did get one thing right: There was 100% chance of weather.

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