El Nino's warmth has slowed Blue Ridge leaf color. A Clemson ecologist says the wait could bring one of the most vibrant falls in years.

Let's call the science straight. The Blue Ridge Mountains are still more emerald than amber, and a Clemson University scientist says that may be good news. Forest ecologist Donald Hagan says warmer temperatures, influenced in part by El Nino, have slowed leaf color development across much of the Southeast, delaying the change that usually begins in early fall, Clemson News reports. The payoff could be unusually vibrant scenery, with ridges and valleys showing red, orange and yellow at the same time. Here's the chemistry. Leaves are green because of chlorophyll, the pigment trees use for photosynthesis. As days shorten and temperatures cool, trees stop making it, and as the green breaks down, pigments already in the leaf show through: carotenoids for yellow and orange, anthocyanins for red and purple. Warm weather delays that breakdown, and cool fall weather speeds it up. This year there's a second factor. An unusually quiet hurricane season let trees keep more of their leaves. "Strong storms often strip leaves from branches before peak color develops," Hagan said. "This year, many forests remain fully leafed, creating conditions for a more complete display if the weather remains favorable." Color usually starts at the highest elevations. Some of the most dramatic views may come in mid-October up high before spreading into the foothills and valleys, with lower elevations peaking in November. The Blue Ridge Parkway, Caesars Head and the Jocassee Gorges could be among the first places to peak. There's science in the show, too: "Tracking leaf color helps us better understand how forests respond to changing environmental conditions," Hagan said. Planning a trip? Keep your dates flexible, check local color reports and the forecast the week before you go, and pack layers for chilly mountain mornings. Good color is worth the wait, and this year the trees are making us earn it.