From the ABC 7 Weather team

Language of weather: What do "normal" temperatures and "all time records" mean?

February 18, 2011 - 08:00 AM
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Forecasting and reporting our weather words do really mean something. This point was brought home to me many years ago when I would report the day’s high and low temperatures along with the “normal” high and low. I received a very thoughtful and perceptive letter from a parent of a child with some learning disabilities, who pointed out to me the various connotations the word “normal” has in not only meteorology but in our society.

I know that the average height of men today in the United States is 5 feet 9 inches. I am 6 feet 2 inches (well, before shrinking a bit lately) so does that mean I’m not “normal,” or just a bit taller than average?

I am taller than average, I think, not “abnormal.” The parent’s letter got me thinking about the words we use and what they mean. Since that letter, I’ve always (or at least always tried) to report today’s “average” temperature. Today our high of 73 is 26 degrees above average and it certainly is unusual for February, but not a record.

Also, as it again has been pointed out to me on more than one occasion, even if we had broken the record high today and reached 80 degrees it would not be an “all time” record.

Our “official” weather records here in Washington go back to the mid-1800s, hardly all time. There were probably warmer days in February in Washington during the 1200s, 1300s or even 1500s; there just weren’t any thermometers around then to record the daily records.

Our current averages are also the averages for Washington calculated from daily observations and worked through smoothing formulas for the latest period of 1971-2000. These local climate averages are updated every ten years, so the new averages (not “normal,” remember) for the 30-year period from 1981 to 2010 will be coming out later this year.

All fine and good you may say, but what then “should” the weather be. The weather shouldn’t be anything. It just is. As a matter of fact, one of the most unusual days, which occurs only once or twice a year, is a day when the high and low temperature are both exactly what the average high and low for that day are. Does that mean what the weather “should be” then occurs only once or twice a year?

I don’t think so. The extremes of weather sure make it exciting to be a meteorologist. Averages do change. We know with urbanization and changes in land use such as the development of Crystal City just west of Reagan National Airport (the “official” weather station for Washington, D.C.), the average high and low temperatures have increased over the last 70 years since DCA was built.

So keep watching us and reading more about our weather and climate. It is changeable and changing. It always has been and always will. That’s the way it should... I mean, that’s just the way it is.

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