FOX44 - Burlington / Plattsburgh News, Weather & Sports11.23.11 Why We Got More Snow Than I Thought

11.23.11 Why We Got More Snow Than I Thought

When I was looking at this storm on Sunday, November 20 I was taking into consideration many things.  I was thinking where the storm was going, how much warm air could be lifted into it, how much precipitation would fall from it as liquid, and how much of that would be frozen.  Early-season winter forecasting can be very difficult, especially when the temperature flirts with that freezing mark.  One inch of projected snow could easily turn into six fresh inches of snow.

As of Sunday, here were the possibilities of where this storm could go.

All of the diamonds and crosses show the possibilities of where the storm could go.  The black line is the best guidance.  At this point in the forecast I'm thinking, "Okay this is a pretty western track.  If it continues through central New England we're going to get a lot of rain with warm air moving in."  Let's compare the forecast to what actually happened.

The red L's are the actual path that the storm took.  At first there was good consensus on where the storm would be, in fact, very good.  That first L is right on the line.  The second L is good as well. (And by the way, the L stands for the central low pressure) However this is where it turns hairy.  This storm took a right hand jog right toward New Jersey, then a secondary low pressure formed to the northeast (indicated by the dotted 'L').  There were maybe one or two model runs (shown by the crosses) hinting at this, out of dozens.  As a forecaster I typically stick with the consensus and where most of the forecast tracks agree.

As a result, more cold air could interact with the precipitation in our area.  The circled and lined areas show the heaviest precipitation from the storm.  Typically the heaviest rain/snow/ice is to the north and west of the low pressure.  Since the center passed across southern New England, our area was on the cold side and the heavy side of the precipitation.  The result:

A widespread 4-8" of snow fell across the area.  Notice the coastal areas in New Hampshire and Maine did not get much.  That's because those places where closer to the center of the storm, where more warm air mixed in.  We would have been in that position if the storm shifted north.

And of course in Vermont, New York, and New Hampshire the terrain played a crucial role in the amount of snow we got.  For instance my favorite comparison is Rutland to Killington.  Rutland center got two inches of snow, but up U.S. Rt. 4 to Killington, they got 12"!

So these types of weather events are very hard to predict.  We try our hardest, and take these examples as learning experiences.