We’ve all heard or read the local weather reports countless times, and terms like “average” and “near normal” temperatures and precipitation give us an idea of what to expect when we venture outside for the day.
As NPR.org. points out, we hear these terms most often during extreme heat in the summer, or when mild temperatures persist through the winter, or when nights don’t cool down like they used to.
But with a warming planet and the impacts we are experiencing with global warming, what was considered normal 30 years ago is a bit different in today’s world. And because we are living in a changing world, NOAA’s National Centers for Environmental Information (NCEI) has reviewed 30 years of weather and climate data from across the US. and will be updating temperature and precipitation normals that will become a baseline for local meteorologists in forecasting the weather.
It’s not like the changes will be huge across the board, but the fastest-warming places will see a real bump in their averages that could make some forecasts seem confusing and pose a challenge to meteorologists. Basically, this means that the baseline for normal weather from 1981-2010 is being shifted to 1991-2020. Relying on that warmer period means many new “normal” temperatures will be higher, reports CNN.
You may wonder why 30 years of data is needed? Simply put, this is the standard set by the World Meteorological Organization in 1935. That year, the agency instructed member nations to calculate climate normals using a 30-year period, which spanned from 1901 to 1930. Additionally, NOAA will include 15-year normals to better represent a climatology period closer to today.
Mike Palecki, the project manager for NOAA’s 1991-2020 climate normals says: “Preliminary analysis shows that the Climate Normals for 1991–2020 are generally warmer in most seasons and regions of the United States, but not everywhere.” He notes that the North Central U.S. region temperatures are somewhat cooler than those based on 1981–2010, especially in the late winter and spring seasons.
He adds: “Precipitation normals also change for 1991–2020, with increases especially large in the Southeast and South Central U.S., and distinct seasonally dependent shifts in the West.” Additionally, Palecki says, “It is also very clear that in some regions of the U.S., occurrences of above-normal days have increased, and the 30-year normal is no longer as fully representative of the region’s current climate.
“These new normals are a better baseline for today’s climate, helping inform activities in many economic sectors,” said Palecki. Climate will continue to change in the US during this decade, however, so we will need to do this again in 2031.”
