How and When Will We See the Leaves Change Color? 2016 Fall Foliage Forecast (credit: SmokyMountains.com, National Drought Mitigation Center)
DISCUSSION: With the arrival of astronomical fall a little more than a week ago, cooler temperatures have already taken over parts of the United States with shades of red, orange, and yellow coloring nature. Deciduous trees and plants are beginning to lose their green coloring and, as a consequence, more colorful landscapes are starting to take over. How does this happen? Basically, as the amount of daylight decreases due to a change in the sun’s angle, so plants receive less sunlight which inhibits their ability to photosynthesize sunlight. As a result, they produce less chlorophyll, which is what gives them the green coloring, leaving behind a combination of reds, oranges, and yellows.
Weather influences the onset and duration of which how long these fall colors stay around before the leaves drop or turn brown. In areas with more precipitation, gorgeous fall colors tend to last at least a few weeks. In areas experiencing drought, chlorophyll production is hampered even more, so colors may not be as vibrant or may only last a short time. Such is the case in New England, where nearly 80% of the region is experiencing a moderate to severe level of drought, as demonstrated in the graphic below (courtesy of the US Drought Monitor), resulting in an earlier peak of fall foliage in New England than is typical. In addition to precipitation, temperatures affect fall foliage as well. For example, strong cold fronts bringing arctic air masses down south from Canada into the US can kick start the process faster, leaving them to abruptly turn brown rather than slowly fade into different hues. In contrast, above normal temperatures help the leaves to continue producing more chlorophyll or maintain the same sugar levels in the leaves, allowing the leaves to keep their color longer.
This year, we have faced drier conditions in New England and along the Northwestern coast. For the most part, temperatures have remained around average for this time of year across these areas. So, fall foliage for the Fall 2016 season is expected to continue as it has in past years with the exception being those two drought-affected regions. As depicted in the image below, courtesy of SmokyMountains.com, fall colors have already reached their peak in northern New England, and are peaking currently along the Rocky Mountains and in northern Minnesota, where temperatures have already approached or reached freezing. In comparison, across the southern states where it has been warmer and where there has been above average precipitation, the peak of fall foliage is forecast to be a little later than normal, in late October/early November. To see the forecast in more depth, check out SmokyMountains.com. To learn about other weather educational topics within meteorology, click here!
@Meteorologist Katie McCracken