BOSTON (CBS) – Welcome to the new normal.
No, not normal social distance wearing the mask, that is the new weather normality.
I bet if I asked you what the “normal” weather was like at any given time of year, I would get a whole bunch of answers. One person’s weather misery is another person’s dream. But believe it or not, we actually have a well-defined set of normal weather conditions for every day, month, season, and year. These conditions are based on 30 years of data. These are the numbers we use on TV every day when you hear our weather forecasters report above or below average temperatures or precipitation deficits or monthly / annual snowfall amounts compared to normal. NOAA has a defined set of weather averages and is based on weather data for the past three decades. For the past 10 years, meteorologists have based their data on the 1981-2010 dataset.
Now that we’re decades old and have new weather data worth another 10 years, NOAA has shifted its norms to be based on records from 1991 to 2020. Basically we’re throwing out the 80s (no more hairbands or hammer pants) and adding them in the 2010s.
When I say “kick out” I don’t want to give the wrong impression. We’re not just discarding old data, all data stays on our long-term climate records (for Boston, this goes back to the 1870s). These 150 years of data are still vital. In this way we can compare modern times with pre-industrial times and take a decisive look at how our world is changing (for better or for worse).
However, when it comes to daily / monthly / yearly normals it is much more accurate to do this with the last 30 years of weather records, so bye 80s, hello 2010s.
How is that changing things? As you can imagine, the temperature normals are for the most part warmer. Does this measure mean that the snowfall normals have to be at the bottom right? Not correct! Let’s dig deeper into the new data … and pick out some of the more interesting changes …
No wonder our average annual temperatures are rising.
In Boston, the annual average rose from 51.5 degrees using the old data set to 51.9 degrees using the new numbers.
The average annual temperature in Worcester rose from 47.9 degrees to 48.1 degrees.
In Boston, temperatures got warmer in all four seasons, with the largest increases occurring in the fall and winter:
- Winter rise: +0.7
- Spring rise: +0.3
- Summer rise: +0.5
- Fall rise: +0.6
If we look at the monthly changes in Boston, we see an increase in 10 months out of 12, again some of the biggest increases in the fall and winter months:
- January: +0.9
- February: +0.1
- March: no change either
- April: +0.5
- May: +0.5
- June: +0.3
- July: +0.7
- August: +0.6
- September: +0.7
- October: +0.8
- November: No change either
- December: +1.0
You might think warmer temperatures = less snowfall, but we’re seeing exactly the opposite.
The annual average snowfall in Boston rose from 43.9 inches to 49.2 inches.
Worcester had an even bigger increase from 62.1 “to 72.9”
The monthly average snowfall in Boston saw the biggest increase in February, now our biggest snow month, beating January
- Increase in October from 0.0 to 0.2 “
- November decrease from 1.3 “to 0.7”
- December stayed stable at 9.0 ”
- January increase from 13.1 “to 14.3”
- February increase from 10.9 “to 14.4”
- March increase from 7.8 “to 9.0”
- April decrease from 1.9 “to 1.6”
Why more snow at milder temperatures? My theory would be that warmer temperatures mean more water vapor in the air … more moisture = more juice for blizzards. Not to mention that the oceans are much warmer today than they used to be, which also adds to the total water content in the atmosphere.
So there you have it, your new normal. At least for the next 10 years, until we introduce another new data set in 2031. I have to ask myself what differences we will then see and how our “normal” will change again and again.