Winter Storm Recap : 12/16/20 – 12/17/20

Our first major winter storm of the season, and Poughkeepsie saw practically the same amount of snow between Wednesday and Thursday… as they saw for the entire 2019-2020 season.  Poughkeepsie saw 15.0″ of snow per the National Weather Service report, just one inch less than the station recorded all season last year.  So needless to say, the 2020-2021 winter is off to a fast start.  So lets take a look at the performance of the HVW forecast, against the recorded results from the National Weather Service.  Lets start by looking at the HVW forecast…

Now lets look at the snow history maps from the NWS and snow totals….

 

Hi-Resolution Snow History Map

In totality… our forecast was respectable, and was in the low end (or near the low end) of the forecast range.  In our 10-18 inch forecast range for SE Orange, Rockland, Westchester, Putnam and extreme southern Dutchess counties.  Based on the NWS data, in those areas, we saw a lot of 10″ to 12″ totals.  Beacon, Cold Spring, New City, Warwick, Mahopac… all had 10 to 13 inches of snow.  The Mid Hudson Valley was the region where snow totals were “underwhelming” in terms of the HVW forecast.  A lot of 11″ to 14″ totals could be found.  Very respectable totals, but a tick lower than the 16″ to 24″ which was forecast.  Heading into the Upper Hudson Valley and Catskills… that 16 to 24 inch forecast worked out nicely, with a lot of 1.5 foot to 2 foot totals in those areas.

The forecast was well thought out, the only thing that could not be accounted for, was the track of the upper level low.  When dealing with storm systems like this, the heaviest snow amounts are found just to the NW side of the upper low track.

It’s a subtle difference in the track of the upper level low (ULL).  But on the north side of the upper level low, you find incredible upward motion that generates extremely heavy precipitation rates.  That’s how we accounted for the tremendous snow totals near Binghamton, and extending to Albany and points north.  The forecast track of the ULL would have move over NYC, putting the Hudson Valley in the band of heaviest snow.  That was the primary motivation behind the 16 to 24 inch forecast across the Hudson Valley.  Remember, we had multiple pieces of data that suggested that we were going to be under-done with our forecast.

The most conservative model at times shows this as the result… and the cause was the ULL track expectation to be over NYC.  But in the end… the ULL was just a tiny bit stronger than projected… not even by 1 decameter.  But that tiny difference, was enough to amplify the trough enough to track about 50 miles further north than expected.  And that shift pushed the crippling snowfall to our north.  A very close call… but we’re pretty sure that most people won’t hold it against us.

For the first storm of the year, it is going to be difficult to top.  Odds are it will be the heaviest snow of the season in the northeast… and probably for the Hudson Valley.  But considering how active the weather pattern looks, perhaps that won’t be the case.  Time will tell.  But we thank you all for tracking this storm with us.  We greatly appreciate all of your support… and look forward to forecasting more storms for you as we go through the rest of December, and on into 2021.

1 thought on “Winter Storm Recap : 12/16/20 – 12/17/20”

  1. Yes! If I was 17- 20 Id have taken a walk in it. But Im 59. So I drove in it. I had to drive round trip Napanoch to Kiamisha to Kingston and back again. Ave 40mph. Had to pass a few folks. Left 7:30 got home 11:30. So cool to be out in it! Went to bed 2:00am but when I got up 8:00am there was 1 1/2 times as much snow! From 8” to 20”!!
    For what its worth.

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