Monday, May 09, 2016

Are These Big Spring Temperature Changes Something New?

Many times throughout this spring people have commented to me how they never remember wild swings in temperature in northern Ohio quite like what we've experienced this year.  Rather than assume a specific conclusion, I went back and found the high temperatures for every day since 1975 from March 1st through April 15th and again for April 16th through May 31st. I highlighted each instanced where the day-to-day high temperature change was greater than 20 degrees either. In other words, if the high temperature one day was say 38 and the high temperature the following day was 60, that counted. If the high temperature fell from 75 to 52, that would also count.  Here is what I found.

The number of occurrences haven't varied a lot over the last 40 years between March 1st and mid April. I thought the numbers would have been higher since the late 1990s.

Historically, large temperature fluctuations after April 15th don't occur as often due to the lack of residual cold air left over from winter. So far this year (2016) we haven't had an occurrence since April 15th.

What I found interesting is that the occurrences of day-to-day high temperature drops of 30 degrees is significantly higher than temperature jumps of 30 degrees especially before April 15th.

As much as perceive these fluctuations to be a new thing here in northern Ohio, it is quiet common in early spring and has been for at least 40 years. This is another classic example of the Recency Effect as work.  That is we overly weight in our minds more recent events with greater significance and quickly dismiss events further back in time. Note that these conclusions are derived ONLY from Cleveland temperature data.