Some computer model runs proceeding the storm tantalized snow lover with several inches of fresh powder and many hoped the two pieces of atmospheric energy would come together to bring up to 8" of snow to the area. Alas, this was not to be and the benign winter across the Northeast continued.
As many weather enthusiasts mourn the loss of snow to the fish and other marine life, let's take a look at two things that should have been red flags as this storm developed.
Leading up to the storm, computer models continued to output varying amounts of liquid equivalent. Ranging anywhere from zero to over a half an inch, forecasters tried to form a consensus and decide on how much liquid would actually fall, translating it to snowfall amounts. In the end, most places from Philly to NYC saw around a tenth of an inch of liquid which amounted to only a trace of snowfall on grassy surfaces. While the bulk of precipitation did indeed go out to sea and the storm never fully organized in time to bring heavier snow to the area, one thing shown on the computer models should have been taken into account more heavily--the lack of precipitation in 6-hr periods.
From what I remember, (and if I'm wrong, I hope someone will correct me) many of the forecast models showed 0.05-0.15 inches of precipitation in 6-hr time periods, sometimes amounting to around 0.30 inches in 12 hours. For the sake of simplicity, let's say 0.12" was forecast in 6 hours. That's 0.02"/hr which, with a standard 10:1 snowfall ratio is 0.2" of snow per hour. So with this hypothetical situation, you would expect 1.2" of snow in 6 hours. But weather is much more complicated than multiplying by 10. If you're getting snowfall at 0.2"/hr and the surface temperatures is 34, and the snow is falling during the day, you aren't going to get meaningful accumulation. Plain and simple. These were the conditions in NYC on Saturday morning and therefore, only a coating.
The minimal QPF shown on the models should have been a red flag in addition to the warm boundary layer. Although surface temperatures ended up being a bit colder than forecast, they still were not chilly enough to allow snow to stick to paved surfaces--the light snowfall rates contributed to this as well.
The second thing that should have been noticed on Thursday night, 24 hours before the snow began in the Northeast, was how poorly the models (especially the NAM) were handling the moisture associated with the southern shortwave. Unfortunately, I don't have the graphical images so bear with me for an explanation.
A little after midnight Thursday night (early Friday morning) rain was spreading into south central Louisiana. By 12z Friday, the rain was almost into Mississippi. The 0z run of the NAM 12-hr prog showed it DRY across ALL of Louisiana. Translation: the NAM was too slow right off the bat with the southern shortwave. What did the 0z NAM show in terms of snow? At least several inches for NYC with around a half inch of QPF. But this obviously had an extremely slim chance of happening as the NAM at 12 hrs was already too slow with the southern shortwave.
Why is this so important?
This storm hinged on the northern and southern pieces of energy interacting closely. With a faster southern system and I would argue slightly slower northern system, the storm never had a chance as of early morning Friday to come together in time to bring moderate snowfall to New York. For all intensive purposes, in hindsight, the snowstorm threat could have been cancelled at 2am Friday.
So we'll move into the second half of February still without a significant storm for New York City and weather weenies ready to tear down the message boards, praying, wishing for snow (and bashing others in the process--why can't we all just be friends and talk about the weather politely but with passion? That's a topic for another time though...).
