Well we think this graphic is pretty damn cool!!
This is our final forecast issued prior to the onset of the storm on Sunday, the second image it fades into is an amazing preliminary observed snowfall map created by Tomer Burg who operates a site called PolarWx (you should check it out).
Overall- We are beyond pleased with the outcome of what was really a pretty difficult forecast. If you’ve been with us for a while you probably know we obsess over the details. It’s been known for us to spend over two hours trying to get every contour perfect. We only put out three maps for a storm, “First Look, Prelim and Final” and we try to keep the changes between each version minimal from the previous.
We want your trust and we earn it through this obsession for accuracy and commitment to facts and not hype. We don’t discuss storms beyond 4-5 days unless we feel that the pattern and signal are aligned enough to support it being a possibility. We post nothing for clickbait and we don’t hide any of our forecasts behind a paywall. All we ask is for your support through our subscriber link at .99 a month and you to share our content far and wide!
Our early concerns for a sharp cutoff gradient came from a few places, as model guidance didn’t really catch in till it was too late. Our early first look snow map even had a sharp western and northern cutoff. The main driver of this concern was simple, history is a good tool for good forecasting.
We studied three recent events, 1-25-15, 12-25-10 and 1-27-22, all three of these events featured storm coastal storms that tracked east of 40N/70W (The Benchmark). In all of these instances a sharp N/S or SW/NE snowfall gradient setup directly through our forecast region. In fact, two of these storms screwed up previous forecasts of ours, the scars are still there! Every missed forecast isn’t to us a part of forecasting, it’s something to go over again and again in order to get better.
Second red flag, the only models really keeping our entire region in the highest snowfall amounts were the ones that have a known bias to keep these kind of storms too far NW! Again, models are tools, not forecast makers, it’s important to know the weaknesses of your tools. The GFS was good with the storm for most of the forecast period and was very consistent with its idea that a storm was be present. It was correct and scored a big victory vs the flagship Euro model. It’s only flaw is that it also continue to lean to far west, when the European model caught on later in the game, it never quite committed to the western most envelope and stay a touch east. Many forecasters dismissed it as being an outlier because of its failure to recognize the storm earlier, this ended up being a mistake.
Many of the short range models painted a widespread 20”+ snowfall for almost the entire 10 county region with the exception of the furthest western and northern edges. It was hard to ignore this as these models are in their top accuracy range inside of 36 hours. Due to their bias, historical accuracy, and intuition, we forecasted totals about 30-40% lower than some hires modeling. We were also more aggressive with our lower amount contours on the north and west sides, and we over communicated the low confidence and where are concerns were. Finally on Sunday around mid-day we really raised the “Bust” alarm, and then followed that with a map visual of are concerns to make it even clearer, that is the map you see below.
In addition to the map comparison, below are several snippets from our forecast leading up to the event. We always do recaps after larger events, even when it’s not a victory lap. We do these out of spirit for transparency, ownership, accountability and to teach and learn how we can continue to improve for all of you.
Thanks for trusting us, thank you to our subscribers, partnerships, and advertisers. Now on to the next one!
Keep Calm and Weather On!
-Alex
Quote from Thursday Forecast- “Short range models have a bias to over amplify these system and they may be too far NW with their solutions”
Quote from Friday Forecast- “Snow totals subject to change depending on precise storm track .. Sharp cutoff on western edge, is area of greatest”
Quote from Saturday Forecast- “The same can be said for the 6″ to 12″+ range. The western edge of this system will see a sharp and dramatic cutoff in snowfall accumulations. Where that western edge sets up is of GREAT concern to our snowfall forecast. The combination of marginal temperatures (near freezing) and potential downslope off the Catskills only increase the uncertainty in these areas. At this time, we feel the edge is in eastern PA, up through western Delaware county. But should the guidance shift eastward again… we could see the lower ends of the forecast. Should the data shift further west… the totals forecasted could be exceeded”