Ask Storm Team 11: New climate normals suggest more rain and less snow in Tri-Cities


Tuesday’s Ask Storm Team 11 question explored the new normals for the Tri-Cities. What do I mean?

Every 10 years, NOAA updates the 30-year climate averages from temperatures to precipitation. When you see us show the almanac on the weathercast, it highlights the highs and lows normalized on a particular date now spanning from 1990 to 2010.

On a national level, temperatures showed an upward trend except in the Midwest and northern Plains.

On the other hand, the eastern U.S. has seen more rainfall on average with drier than average conditions out west.

Locally, some of the key takeaways are that the average rainfall went up for all four seasons, especially the winter and spring, and every month except September.

September and October are still our driest months on average.

The biggest jump in normal rainfall occurred in March and April averaging about a half-inch higher each of those two months between the 1980-2010 normals and the new 1990-2020 normals.

Our average yearly rainfall is now 43.97 inches.

What’s also interesting is that the average annual snowfall dropped 31 percent and is now 9.2 inches in the Tri-Cities over the last 30 years. That’s partly because the average temperatures for most months have increased with the exception of November when there was a slight drop.

When you take all the highs and low temperatures, we’ve seen our average temperature go up about 1 degree for this 30-year span compared to the last one.

Remember, the warmer it is, the more water vapor the atmosphere can hold. This explains our uptick in rainfall as a whole.

Have a question for Storm Team 11? Click here to submit!

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