Craig Koplien: Weather or Not

Why Am I Sometimes More Sure About The Forecast?

Story Created: Sep 12, 2008

Story Updated: Sep 12, 2008

Why Am I Sometimes More Sure About The Forecast?

Craig Koplien

email: ckoplien@todaystmj4.com

I was asked the other day about why meteorologists are more certain about what the weather is going to be like on some days than others. That’s a good question with 2 key answers.

The first reason is that we are always more certain in the short-term rather than the long-term. When we can see an actual thunderstorm or snowstorm moving toward us, we can easily gauge when it will arrive. In addition, the computer projections that we use to help us forecast the weather are almost always more accurate a day or two in advance than they are 6 or 7 days.

The second reason also deals with computer projections and the fact that there are many of them. Sometimes these multiple projections all converge on a similar forecast. In those cases, we can be confident in what our future weather will be. Other times, however, the projections give us conflicting information. In those cases, we are less certain about the forecast.

By the way, multiple computer projections are needed because no single one has been developed yet that is accurate in all situations. These projections use mathematical equations to attempt to forecast future happenings in the atmosphere. While the workings of the atmosphere can be approximated using these equations, it cannot be exactly replicated. So, multiple projections have been developed, each using slightly different math and approximation techniques.

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