Interactive map: When autumn leaves will reach peak color in this area

photo A maple tree is in full fall splendor at Cloudland Canyon State Park.
photo Fall trees show leaves of red and gold in the Great Smoky Mountains National Park.

Wes Melton has created a map that has geeks swooning nationwide.

Melton, co-founder and data scientist at SmokyMountains.com, the website dedicated to the national park, has created a fall foliage map that lists the dates that every county in America will morph from a sprinkling of autumn leaf color to glorious peak splendor.

Even more impressive, Melton based the map's predictions on more than 32,000 data points, including National Weather Service facts - day and night temperatures, rainfall, humidity, etc., in months preceding autumn - and also observations from sources such as leaf-change bloggers (yes, it's a thing) and farmers' almanacs. It took him about six months to analyze all the data, he says.

"I plan to do a fall foliage map every year and post it on Smoky Mountains.com," the Gatlinburg-based Melton says. "One thing that is clear to me is that I underestimated the impact of climate change on fall colors. Californians have called to tell me that the severe drought they are experiencing had a terrible impact. Leaves fell off trees or went straight from green to dead and brown. Next year, I'll find ways to evaluate the climate change impact more precisely."

Harvard recently released a new study examining climate change's impact on fall colors. It agreed with U.S. Forest Service research on one key colorful point: Enjoy spectacular reds while you can. They will become a distant autumn memory for most Americans.

The maple trees that blaze in a rainbow of red each fall are migrating northward to avoid warmer autumn temperatures. Forest Service computer models show the maples may eventually grow only in Canada.

"When travelers gasp over a beautiful autumn view, what they are reacting to is the red leaves in a landscape," says Jesse Pope, education director and biologist at Grandfather Mountain in North Carolina, the highest peak in the Blue Ridge range. Pope has recorded daily observations of seasonal changes and meteorological measurements in his 13 years at the park's naturalist.

The computer models also show different tree species changing color at different times rather than in one grand sweep due to warmer September nights. The result is color that shows up in patches across the autumn landscape, less dramatic visually than all the trees changing colors at the same time.

"The computer models I've seen indicate that climate change will make North Georgia's autumn colors less intense and more scattered," Pope says. "Due to higher elevation, mountainous Eastern Tennessee and western North Carolina theoretically will be more buffered from climate change."

But Melton's map shows this area already suffering from the patchy color problem. Tennessee counties from Hamilton, Bradley and Marion across the Georgia line to Catoosa, Whitfield and Murray counties are enduring the patchy color problem. By Saturday, colors in those counties will be only at partial peak, according to Melton's map, with the peak on Nov. 1 then promptly plummeting to past peak.

Future autumn travelers craving vibrant autumn panoramas of crimson, gold, orange, pumpkin, rose and indigo that send human spirits skyward will have to seek higher elevations. The higher the mountain, the less buffeted it will be by climate change. For example, Grandfather Mountain in North Carolina is currently enjoying gorgeous peak colors. It has a 5,945 elevation preserves the season's brilliant hues. In comparison, Lookout Mountain is 2,388 feet tall while Signal Mountain is 1,703 feet.

These fall color frailties could be a hard blow to fall foliage tourism. Appalachian State University biologist Jennifer Geib estimates that fall leaf lovers pump $30 billion annually into the 24 states comprising the eastern half of America.

But things may be worse out West, Pope says.

"All the predictive models I've seen show drought getting worse in the West, which means trees just shut down rather than go through the photosynthesis that creates the fall colors we love," Pope said.

Rainfall in the summer is a key to good fall color, he says, especially in the month of September.

"Trees need sunny days and crisp cool nights for great fall color," he says. "The abrupt temperature change at night is crucial. When climate change lessens that dramatic change, fall colors are dimmer and more likely to go from green to muddy yellow or brown."

Pope remains optimistic that further research into the fairly new topic of climate change and photosynthesis may yield some answers about how to protect the Smoky Mountains' and Appalachians' brilliant falls.

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