Thursday, September 26, 2013

Fall Color Outlook

It is a chemical process that begins to trickle to a halt as Autumn begins...shorter daylight and cool and crisp nights begin to halt the production of chlorophyll within the leaves of trees.  The lack of chlorophyll is directly due to less sunlight from the now distant long summer days.  The process of HOW the leaves change colors is science that happens every year, but there are many meteorological (weather) factors that influence just how vibrant the fall colors will be during the season. 

Here is what I expect this fall season of colors to look like. Many of the conditions for the fall color season have already been determined based directly on the recent summer weather.  Summer was ideal, with cooler than normal weather and above average precipitation.  Here are the results:

June: 69.1° (-0.4)
July: 72.2° (-1.3°)
August: 70.1° (-1.4°)

Average Temp: -1.03° Below Normal

June: 6.35" (2.78")
July: 3.94" (0.71")
August: 2.00" (-1.15")

Precipitation: +2.34"

Overall, summer was COOLER than normal and WETTER than normal, although most of the surplus of rain came through early June and July with a dry end to the summer during August.  Despite that adequate precipitation overall and the lack of extreme summer heat put the trees in great health for the change of colors.  This is in stark contrast to last summer where record heat, a searing drought and scorching temperatures put significant "stress" on the trees throughout the entire summer.  This lead to a relative dull and lackluster appearance of the fall colors in 2012. 

We are in great shape now entering into fall, but going forward conditions must remain right for the fall colors to flourish.  Ideal conditions would include lots of sunny days, with regular intervals of rain (once or twice a week) and clear cool nights.  It is ideal to keep sufficient deep sub soil moisture with regular rain.  The clear cool nights help to gradually slow the earlier mentioned chloroplyll production which produces the "green" color of the leaves during the summer.  Without the chlorophyll, the true pigments and colors (yellow, orange, red, brown, etc) show through brightly.  It is also necessary to avoid an early season deep freeze.  A deep freeze before the peak of the fall color season could quickly damage leaves resulting in an abrupt transition to more dull brown colors.


The typical peak of fall colors in this area is the middle of October.  I expect vibrant colors this fall season.  Possibly the best in several years, if we can maintain regular rainfall.  It is slightly less than ideal that September is below average for precipitation so far at 1.67" (-0.67") if this continues it may somewhat limit the peak colors.  I do expect fall colors to peak the week of October 13th through the 20th.  It would likely be on the earlier side of that timeframe across southern Michigan and toward the end of that week (October 17th -20th) in Ohio.  Enjoy the beautiful fall weather and thank the great summer weather we had for the great fall colors ahead!