There is a season, turn, turn, turning leaf colors subtly across West Michigan


    Leaves across West Michigan have started to show hints of fall, although so far not much change has been noted. (Newschannel 3). <p>{/p}

    Hey Joe, if you've been paying attention the trees have started to show hints of autumn and The Byrds are starting to fly south. It might be easy to forget that fall has arrived with temperatures in the first half of September, at times, feeling like summer, but those colors will soon be playing music for the eyes.

    THE SCIENCE OF IT ALL

    To review what you might have learned in fifth grade science, during the spring and summer months, trees actively produce a compound called chlorophyll.

    Chlorophyll is found in leaves and is a key player in photosynthesis, responsible for turning sunlight into energy for the plant. It's also what gives leaves their green pigment during the spring and summer.

    As the we transition from summer to fall, our days become shorter and nights grow longer. This might make it harder to get out of bed in the morning, but for plants, and more specifically trees, longer nights trigger a change in their biochemistry.

    Michigan State Extension educator Linda Whitlock explained as daylight hours decrease, "the leaves in deciduous trees are no longer necessary and the plant goes into a survive-winter mode."

    The leaves are triggered to fall off, and Whitlock said, "the rest of the plant can then use the stored energy to help it survive the cold temperatures, the winds, all that goes with winter weather."

    As trees prepare to shed their leaves, chlorophyll production begins to slow before eventually shutting down.

    "At the end of the year when the leaf is going to be dropped, the plants want to recover some nitrogen by breaking down the chlorophyll," Dr. Todd Barkman, a professor biological sciences at Western Michigan University, said. "The wonderful thing is once they've done that, they leave behind some of the less expensive pigment molecules."

    The other pigment compounds called carotenoids and anthocyanins become more pronounced. Each molecule corresponds to different lovely fall colors. Carotenoids are responsible for orange and yellow hues, while anthocyanins the reds.

    WEATHER IMPACTS VIBRANCY

    Now that you're smarter than a fifth grader, it is important to know the relationship weather and climate plays in either amplifying or hindering the fall colors that we so love during the turn of the season.

    There are several key factors that lead to more or less vibrant color one year versus the next, and the entire growing season must be considered. Extremes in temperature and precipitation are generally bad news for gorgeous fall color.

    Ideally, the growing season shouldn't be abnormally dry, especially during the beginning of spring when plants are just taking off. So a warm and wet spring is best.

    As we get into summer, it's important that our weather isn't too hot or too dry. Extreme summer heat and drought can lead to a total shutdown of the metabolic process once early fall rolls around, causing some leaves to skip changing color all together or brown early. Mild dryness, on the other hand, can slow it down, causing leaves to change a little later than normal.

    When fall rolls around, warm, sunny days combined with cool, clear nights are best for producing a quick, colorful change in the leaves. Warmer than average heat in the early fall can be detrimental to fall leaf color. Freezing temperatures earlier than normal also aren't ideal for prolonged color.

    Once leaves start to change, storms featuring rain and wind are the biggest culprits for causing leaves to fall quickly, therefore shortening the fall foliage viewing season. On average, in Michigan, the Upper Peninsula typically peaks late September into early October, while The Mitten is a few weeks later, in early to mid October.

    2018 OUTLOOK

    April 2018 was one of the coldest on record in West Michigan, but the last day we saw temperatures dip to at or below freezing was April 30. This is significant because the date of the last frost is traditionally used to define the beginning of the growing season. It just so happens to be right on schedule when we compare it to our climate averages in the area.

    May was the polar opposite in terms of temperatures. 2018 would go down as one of the top 5 warmest Mays on record. It also featured above average precipitation, with 3.91 inches more than normal. As we learned above, a warm and wet start to the growing season is best for fall colors.

    Then came summer, which was just slightly warmer than normal and drier than normal. By mid-July, slightly below average precipitation led to minor drought conditions impacting parts of West Michigan. Again, this wouldn't be totally bad news for the fall leaves.

    That brings us to September, which as of September 20 only had four days reported cooler than average in terms of temperature. The warmer than average and hot weather in recent weeks could be bad news for fall color in 2018.

    There is some hope in the forecast, however, as temperatures more typical of fall are on the way in the coming weeks. Several days with warm, sunny afternoons and clear, crisp overnights are on the way, which could trigger those leaves to really start popping out with color.

    The abnormally dry spots across the area coupled with recent warmth both lead me to believe this year's fall color could come a few weeks later than normal. Look for colors to peak in the UP during the first and second week of October. The lower peninsula should see the best color this year in the mid- to late-October time frame.

    2018 PEAK FORCAST

    A look at the fall foliage outlook for the beginning of October. (Severe Weather Center 3)

    A look at the fall foliage outlook for the beginning of October 8th. (Severe Weather Center 3)


    A look at the fall foliage outlook for the beginning of October 15th. (Severe Weather Center 3)

    By the last week of October, the upper peninsula will be past peak, while West Michigan will be right in the middle of it. (Severe Weather Center 3)

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