My outlook for the upcoming winter is that it will be generally warmer than normal with slightly above normal snowfall. That snow forecast, calling for a seasonal total of 10-15″ for the Richmond area, hinges almost entirely on us getting hit by a nor’easter at some point during the winter. If that doesn’t happen, the forecast will bust, but I do think the odds favor at least one such storm this winter. We’ll see.
This “one big storm” scenario is typically how we receive most of our snowfall during a so-called snowy winter. It is the single 6-12″ snowstorm that will help skew a winter’s totals from below to above the long-term average.
All that being said, our patterns this winter will be governed by many different variables, but the biggest commonly talked about is El Nino. This warm anomaly in southern Pacific sea surface temperatures west of the coast of South America has been linked with certain winter jet stream patterns over North America.
This El Nino is moderate, and NOAA’s Climate Prediction Center expects it to maintain it’s current magnitude for most of the winter. The result would favor an overall continuation of the weather patterns we’ve seen lately. A dominant southern jet stream will race storms across the South, while a struggling Polar jet stream makes stabs at cold air intrusions, particularly over the Midwest. But truly cold air, while making repeated dips into the U.S., will be hard pressed to persist. This could change, with highest odds for that during late winter.
Other players in the grand scheme are the North Atlantic Oscillation (NAO), the Pacific Decadal Oscillation (PDO), Canadian autumn snowpack, soil mositure levels, and many other factors that are all intrinsically tied together, yet tempt us too much to over-analyze. I won’t bore you with the details here.
As I write this blog, there are indications that the first half of December may give us an appropriate kick-off to the winter, with a few transient shots of pretty cold air, with a storm track that will favor rain here and snow over the Midwest.
* posted by Jim Duncan