The Big Picture

Friday
January 3, 2014

Today's snow day marked the 6th cancellation for the Kingston City School District. With at least two months of winter left, this undoubtedly raises the question: What about spring break??

Well, the following is a general outlook on the winter season as it pertains to spring break.

Over the last nine winters there has been an overwhelmingly strong correlation between the number of snowfalls greater than ONE inch (1+"), and the number of school impacts. As a general guideline, the number 1+" snowfalls tends to equal the number of cancellations and delays combined.
Note: the term "impact" will refer to the number of delays+cancellations

So far this season we have had five 1+" snowfalls.
We have also had 6 snow days and 1 delay, for a total of 7 impacts.
Of these 7 impacts, two of them were the result of lingering poor conditions from the previous day, and were effectively part of the same storm.
The point: this season has stuck to the 1+" guideline pretty well.

Extrapolation:

Given that the first snowfall of the season occurred on November 23rd, and that the average last snowfall date for Kingston has been the first or second week of March, this weekend puts us about 40% of the way through winter.

If we were to continue at the current rate we would be looking at about
8 additional 1+" snowfalls… for a total of 13. Applying both the standard 1:1 impact to snow event ratio and the 7:5 ratio observed this winter produces a total range of 13 to 18 school impacts… or an additional 6 to 11. Again, "impacts" refers to the number of cancellations AND delays, so only about half of these 6 to 11 should be cancellations… suggesting an
additional 2 to 6 cancellations.


This is text heavy.
Take a quick break,
if you need to.


Now, this is all fine and dandy, BUT so far it's all been straight extrapolation … that is, these numbers pretty much rely on a continuation of the same storm frequency continuing throughout the remaining 60% of winter. No one knows if this will happen, or not. What we can compare it to, however, to get a better idea is the past.

Pre-season forecast:

What I mean by this is, at the beginning of the season, Kingstonsnows issued a seasonal forecast based on patterns from previous years. The forecast called for a season total of 38 to 45 inches of snow, and 8 to 10 one-inch-plus snowfall events.

Based on this forecast we would have expected:

  • Up to 18 inches of snow so far … we're at 22.8 inches
  • Three to four 1+" snow events … we're up to 5.

So, this winter has been slightly out performing the forecast thus far, but the forecast is still valid…albeit on the low side. Applying both the standard 1:1 impact to snow event ratio and the 7:5 ratio observed this winter produces a total range of 8 to 14 school impacts… or an additional 1 to 7. Again, only about half of these should be cancellations… suggesting an additional 0 to 4 cancellations based on the pre-season forecast.


Overall:

Extrapolation projects an additional 6 to 11 school impacts
… suggesting about 2 to 6 additional cancellations.

The pre-season forecast projects an additional 1 to 7 school impacts
… suggesting about 0 to 4 additional cancellations.

Best bet at this point is to blend the two, giving:

3 to 10 additional cancellations+delays
… with an average of 6.5, and maximum range of 1 to 11.

1 to 5 additional cancellations
… with an average of 3, and maximum range of 0 to 6.

If these numbers were to verify, Kingston would likely be looking at at total of 10 to 17 impacts, and 7 to 11 cancellations. Kingston does not begin to lose spring break days until 8 snow days are reached. Each successive snow day results in the loss of one spring break day with spring break bring a mere three-day weekend once 12 snow days are reached.

The record number of cancellations over the past decade is 9, set during the 2010-2011 school year. The blended projection puts us right on par with this record… with a decent shot of eclipsing it.




I was going to post an explanation as to why we keep seeing snowstorms followed by milder temperatures with rain, but I'll save that for later this weekend.

For those of you who are wondering, however, just know that this season's pattern has been a battleground over the northeast with relatively small storm-track differences having large consequences on our weather. This pattern looks to remain in place for at least the first half of January.

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