Courtroom Climate: Weather conditions throughout year affect foliage
Posted: 5:13 pm Mon, October 29, 2012
As the last of autumn’s leaves float to the ground in the coming days, we can be thankful for one of the most vibrant fall color seasons in years. Interestingly, this comes after direr predictions of a lackluster season due to weather extremes.
So, why were this seasons’ colors aglow?
Every year as the late summer and early fall nights grow longer, the process of leaf change begins. In response to the shortening days and declining intensity of sunlight, the veins that carry fluids into and out of the leaf gradually close off, clogging sugars in the leaf and resulting first in color change and then leaf drop.
The brilliance of fall’s leaves is dependent upon weather conditions during the time the chlorophyll (the stuff that makes leaves green) is dwindling.
A succession of warm, sunny days and cool, crisp but not freezing nights combined with adequate soil moisture brings out the best color, especially if preceded by a warm, moderately wet spring and a summer free of extremes.
A check of the weather records shows that last year featured the second wettest spring ever in Rochester. This was followed by a hot and dry June and July only to give way to a wet, sometimes gloomy September and October. Given these conditions it is not surprising that last year’s color season lacked luster.
This year brought record warmth and significant cold in spring and below normal rainfall. The summer was sunny and warm with one period of significant dryness. Then September arrived warm, but turned out cool and wet.
Hardly ideal conditions for flaming fall foliage.
But that is exactly what we had. Perhaps the fact that the second half of September brought decidedly cool (but not freezing) nights did the trick. We may never know. I do know that I am thankful that I don’t have to predict fall colors.
I do predict the weather, however, and that can also be a daunting task.
While our winter outlook remains a work in progress, I can tell you that if the current sea surface temperature pattern in the western Atlantic Ocean and central/northern Pacific Ocean were to remain in place, the winter in much of the continental United States would be colder than normal based on the expected jet stream configuration that would ensue.
But will that ocean pattern remain in place? That is something I am in the process of assessing.
I do believe, however, that this ocean regime will stay in place for at least the next four to six weeks. This implies, given other considerations, that November and the first half of December will have a generally cold look nationally, and much colder than the same period last year in many areas. The Great Lakes region and the interior Northeast may be an area of particular interest.
In the Rochester, Western New York, Finger Lakes area, the implication would be for colder than normal conditions in November and early December with above average snowfall, especially in lake-effect and elevated parts of our region.
I will have more next month.
Kevin Williams is president of weather-track.com and director of meteorology for News 10NBC.