December 22, 2009 — This weekend's snowfall was one for the books – record books and textbooks.
"It was an absolutely textbook case of how to produce plenty of snow in Virginia," said Jerry Stenger, the University of Virginia climatologist.
A coastal low-pressure system developed in just the right location off the Georgia coast, Stenger said. It gathered strength moving north along the coast, following a track that optimized the snowfall.
"There was plenty of cold air already in place at the surface and aloft, so it could be an all-snow event," Stenger said. "The cold air also made for fluffier snow than we typically get. Just be glad that low didn't move any slower. We'd be in bigger trouble."
As it was, the storm dropped 20.5 inches of snow, as measured at the McCormick Observatory, making it the fourth-heaviest snowfall in 113 years. The heaviest snowfall was in January 1922, when 24 inches of snow fell. March 1962 saw 23.8 inches fall and there was 21 inches of snowfall in January 1996.
The storm left many local roads virtually impassible for much of the weekend and many roads were still not clear as the workweek started. The University implemented its inclement weather policy for Monday, asking only essential employees to come to work. On Tuesday, the University returned to its regular schedule, with a two-hour grace period for employees with weather-disrupted commutes.
This winter storm is coming at the end of a year that had seen heavy rainfall, which had relieved concern about the water table following several dry years and drought. While Stenger said he could not predict how much more snow will fall this winter, "the fact that the upper-air flow has been helping to direct moisture-bearing storm systems our way on a frequent basis for the last couple of months makes it a bit more likely than not that this trend will continue, at least for a while."
Weather forecasters are calling for additional precipitation toward the end of the week.
This storm has also put the area over the norm for precipitation this year, which is a positive, though minor, sign coming off several very dry years.
"This snowfall only represents about 1.7 inches of water," Stenger said. "We often get two- and three-day rainfall events of that amount or greater."
He said the ground should be able to absorb the water, since it will melt slowly.
"There shouldn't be any significant problem, except perhaps in some urban areas where storm drains may be clogged with ice and snow." Stenger said. "In and of itself, it's not a big contributor to the moisture reserves, but at this time of year, everything helps."
For more weather information, visit http://climate.virginia.edu/.