What is Normal is Changing
How often have you heard the word “normal” used?
“The engine doesn’t sound normal!” “That behavior isn’t normal!” “I wish everything would go back to normal!”
Essentially, whatever is considered “Normal” would seem to be, well normal, and any deviation from that is a concern.
That same thinking can be applied when talking about the weather.
Meteorologists often refer to "above normal" and "below normal" temperatures or rainfall. In most cases, large differences from “the normal” aren’t good. Rainfall far below normal is often considered a drought, while a drenching rainfall far above normal might be a flood.
But here’s the catch. What’s considered “normal” in meteorology changes. That’s right, it’s normal to change what is considered normal.
Essentially, The Normals are the basis for judging how daily, monthly and annual climate conditions compare to what’s normal for a specific location in today’s climate.
The numbers are called, no surprise, U.S. Climate Normals.
The numbers reflect an average of climate observations collected over the past 30 years at local weather stations around the country; in this case, Raleigh-Durham International Airport.
The U.S. Climate Normals are adjusted every ten years. So, for the past decade, the Normals have been based on weather observations from 1981 to 2010. In early May, climate experts at NOAA’s National Centers for Environmental Information (NCEI) issued an updated collection based on the weather occurring from 1991 to 2020.
The data set reflects a “new normal” that is a better reflection of our changing climate.
And it’s no surprise the new climate numbers at RDU show how our climate is warming. When compared to the previous 30-year climate normal (1981-2010), RDU is about half a degree warmer (0.4).
As you might expect, the warmer climate is reflected in winter weather. If you think you’re seeing less snow, you’re correct. The new climate normal shows RDU sees 0.7” less snow per year. That’s almost one inch less snow then the previous 30-year normal.
And since a warmer climate can hold more water, it’s not surprising that the new normal numbers show the area is getting wetter. RDU averaged 46.07” of rain per year. That’s 2.73” more than the previous normal of 43.34”.
Climate change also brings more extreme weather events, and the new normal reflects that when you consider temperatures. RDU averages five or more days at or above 90 degrees. And while there is less snowfall, there are spikes of cold weather. The new normal shows there are four more days with lows at or below freezing temperatures.
In short, the Normals may be shifting, but meteorologists say what the numbers reflect about climate change is perfectly normal.