Clear trend in 1991-2020 temperature and precipitation data: warmer & wetter for southern New England

The 30-year climate period, updated every 10 years, is the standard by which daily/monthly data is measured in terms of relationship to average

By: Tim Studebaker

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NORTON, MASS. (WLNE) – The definition of average weather is different now than it was for the last ten years.  Climatologists have crunched the most recent data defining normal temperatures and precipitation for each day, month, and year across the US.

Andy Nash is the Meteorologist in Charge at the National Weather Service office in Norton.  Nash says, “It’s the smart people down at NOAA’s National Center for Environmental Information – NCEI.  They’re the ones that take in all the data, all the observations.”

Every ten years, the numbers get an update based on the previous 30 years worth of weather observations.  Our new normal values will be based on observations from 1991 to 2020, and will be in use for the next ten years.

Nash says, “And that’s used for just making sure that decisions being made – whether it’s to put in some infrastructure or whatever – are based on kind of what the climate currently is.  It’s a snapshot.”

The takeaway for our area: at TF Green, an average year is now warmer, a trend that shows up in almost every month.  And, it’s wetter and snowier on a yearly basis, but with drier springs and summers.  Although scientifically significant, the difference may not feel noticeable from day to day.

Nash says, “Maybe there’s a day that the high temperature was 72, and now that will be a normal temperature, whereas if we were using the previous normals, maybe that is 1 degree above normal.”

The new normal for the vast majority of the US is warmer, even more clearly visible on maps showing the past 120 years of data.  And for precipitation, the west is trending drier, while the east trends wetter.

Nash says, “Big picture, it’s all part of the climate changing.”

© WLNE-TV / ABC6 2021

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