Part 1 described the unusual shoot growth pattern of trees this year. Here we discuss why this happened.
Everyone realizes that this was an usual summer in eastern North America. We had a mild summer and a remarkable amount of precipitation. This graph (click for full size) is from the NOAA Climate At A Glance dataset . It precipitation over the growing season (May to August) compared with the long-term average. For the entire eastern US, the graph shows the complete absence of drought east of the Mississippi. In fact, it shows the reverse: the green colors show the areas that are above long-term averages in precipitation. We don’t have comparable graphics for Canada, but precipitation data shows no areas of drought in eastern Canada this year. Most of the east was above to well-above long term precipitation averages for the growing season so far (map is for May to August).
And the precipitation was evenly spread – every month was above average for most areas except in the upper Midwest, where August was dry.
As we said, a very good year to be a tree. Just to note how unusual this is, I could not find comparable data for any prior year.