Friday, November 02, 2012

Winter Forecast 2012-13: Our Best Stab

In our first two parts of the winter discussion, we outlined how this is a mixed bag winter in terms of lacking a clear indicator. The Pacific is not clearly showing a Nino but is instead leaning towards a positive ENSO anomaly...just not strong enough to be an official Nino at this point. There are a litany of mixed signals in the high latitude -- good snow cover, poor sea ice...the latter of which suggests blocking patterns but we may struggle to get favorable blocking at times this winter.

This forecast follows similar history to 1992-1993 and 2006-2007 in terms of being positive ENSO winters that featured a fair amount of volatility but were milder than average overall between December and February.  They featured a colder than average February, a warm January, and December varied for both years but both were above average.

The one thing both of these years featured was strong blocking in the second half of winter -- with some harsh weather over a four to six week period.  92-93 featured the Superstorm in March, 06-07 featured two sleet storms in four weeks.  We're not predicting another superstorm nor are we predicting two sleet storms in a four week window.  However, our prediction is that February will be a rather active weather month.

This active period could extend into March, as it did in both of the years (92-93, 06-07).  In any case, a mild start gives way to a chilled finish around here.

In terms of snow, our wild card that we sometimes loathe to predict, we're pegging 20-25 inches for the coming winter.  Our average is 21.8 so we're pegging pretty much right near normal.  If we end up with a blocking pattern that lasts longer and starts earlier in the winter, our snowfall totals have a good chance of ending up higher than this.  It is the big wild card in any winter outlook but given the potential for a few good weeks of winter, we feel there's a good chance at seeing more snow than last winter and much closer to normal snow by the time we're done.

In all, it's a tougher winter to predict than usual...but our thinking is that we end up seeing a mild winter overall but one that features a strong bit of blocking at some point in the winter, bringing us a few week period of colder weather and a chance for most of our snows in the coming winter.