Sunday, January 25, 2026 Snow Review

Meteorology is a science, which means it should follow the scientific method.

We make a prediction, Mother Nature runs the “experiment”, we analyze the data. At least, that is how it should work.

From a purely snow-amount driven perspective, yesterday’s storm underperformed… majorly in some areas. Instead of a widespread 12-18 inches, it was more like 6-14 inches.

Using National Weather Service snow report summaries, I have compiled a map of snow reports across our region.

Reports colored Green met the 12-18 prediction. Orange reports at least had double-digit snow amounts, and red reports failed to reach 10 inches.

Snowfall reports, as recorded by the NWS and mapped by me.

Why Less Snow?

In my post “Friday morning thoughts on Sundayโ€™s winter storm” under the heading “Storm Impacts & Amounts”, I took a lot of effort to explain how snow flake structure can impact the snow-to-liquid ratio (SLR):

Still, we are talking about significant snowfall, regardless. Were this system all rain, we would likely see three-quarters to an inch of rain. A highly assumptive and usually inaccurate rule of thumb is to multiply that by 10. Our climatology says multiplying by 12 or 13 is a very slightly better method. These methods alone push snow totals toward double-digit territory.

 

However, with the cold air in place, multiplying by 15 or 20 is a bit more accurate for this particular system. You can see how that drastically changes the picture, pushing snow totals well over a foot.

 

The truth of the matter is that this snow-to-liquid ratio is not constant throughout the storm. At times it may be over 20, while other times it may drop below 15. It all depends on the snowflake formation and shapes.

The impacts of snow flake structure on snow amounts is something I’ve noticed in these types of events over the last few years… which is why I wanted to bring it up two days before the storm arrived.

It hasn’t been easy to get accurate liquid equivalent measurements to match up with snowfall amounts, but I was able to collect some data from the COCORAHS spotter network. Instead of ratios of 15 or 20… or even 10… many of the ratios I calculated were under 10. That is to say that an inch of rainfall-equivalent would produce less than 10 inches of snow.

When I said “were this system all rain, we would likely see three-quarters to an inch of rain”, that turned out to be true. There were some areas that saw less than that 0.75 inch threshold, many places got over that mark.

So, the primary culprit at play here was the way-off-the-mark SLRs indicated by the models.

One comment on my blog post this morning said:

It was snowing hard โ€“ tiny white needles. Maybe 1/4 or 1/3โ€ณ long. They were light and dry โ€“ easy to shake off my coat. But they fell to the ground and packed into a rather dense layer of snow. Not wet and heavy, but dry and dense.

Other comments I had compared it to granulated sugar or walking through sand.

I’ll include here once again the snow flake structure diagram I included Friday and in an update Sunday afternoon. Click the image to enlarge it.

diagram showing how temperature and humidity change snowflake shape and structure
Credit: Dr. Libbrecht, professor of physics at the California Institute of Technology

In my Sunday afternoon update, I pointed out how some limited data from the NYS Mesonet indicated temperatures in the prime area of the clouds for snow development was too warm for large, fluffy flakes. The observation of needle like structures, which I also mentioned on Friday, confirms that temperatures were in fact too warm aloft, despite temperatures at the surface being so cold.

Accumulating snowflakes shaped like needs is like stacking sheets of paper. Take 10 sheets and lay them on top of each other… it barely is noticeable. Take those same 10 sheets and crumple them into a ball, and the vertical volume, aka the accumulation of large, fluffy “dendrites”, is vastly different.

Doing some further reading on how the weather models (numerical weather prediction models, or NWP models) try to estimate SLR both before and after the storm, and looking at the results of this storm, it is evident that our current modeling capability is… not very good.

From Pivotal Weather, a company that takes weather model data and makes it accessible to meteorologists like me:

From a physics perspective, SLR comes down to the structure and density of the snow crystals, the formation mechanisms of which are quite complex (see Takahashi et al. 1991). Like any such pinpoint-small detail, though, current NWP models can only parameterize (estimate) this based on larger-scale variables like the predicted air temperature, moisture, and wind. Within the model, these variables could theoretically be used in a nuanced way to estimate SLR with considerable accuracy, but this is rarely done in current operational NWP. Instead, external users like Pivotal Weather must estimate SLR themselves based on the more limited data provided publicly.

In other words, the complex formation of snowflakes is more than modern weather modeling can handle.

For many years, I have harped on models overdoing the cold in situations where sleet mixing in is a possibility. I’ve accurately made predictions far below my contemporaries in these situations… often receiving flak on social media for having predictions so much lower than everyone else, but ultimately being vindicated.

This situation looks no different. Thankfully, more model data at more layers in the atmosphere is becoming available, so this will be something I will be placing even more emphasis on in my forecasting process from now on.

Automated phone apps certainly won’t be taking this into account in the future. Weather pages, media, private sector, or hobby pages that simply repost model data and call it their forecast won’t catch this either. Mark it down as another example of why having a local expert science based meteorologist is a vital necessity.

 

Service Analysis

Despite the raw snowfall projections being off, I am still very proud of the work I have done.

Did you know that last year, I madeย zero snow maps. This year, I’ve madeย two.

Even when I did post this storm’s snow map, I did so in a very deliberate way:

The problem with snow maps, or most weather graphics, is the way people use them. In our social media driven, mirco-attention span culture, a snow map is far too often theย only piece of the weather forecast that people see. Now, this is a bit like preaching the choir… Finger Lakes Weather users are not the average consumer! You already know that there is much more to the forecast than a single map can tell.

So if a snow map isn’t useful for the entire forecast… neither is it useful as the only point of reference for seeing how well a forecast did. So, here are some forecasting wins that I had with this event:

Storm timing and danger

While most models had the snow not completely overspreading the Finger Lakes until later in the morning, I pointed out that the models are often too slow and predicted snow would start around sunrise in the south and overspread the region completely by mid morning. It did.

The roads DID become extremely snowy, icy, and dangerous. Travel Sunday would have been difficult if not nearly impossible. The impacts of the storm that I outlined still matched up almost exactly to the impacts that were realized.

Historic Context

In my Saturday morning post, under the heading “How bad will it really be”, I said: “Considering just the snow amounts, this is the type of storm we get probably 3 or 4 times every 5 years. Significant, but not one for the record books. In recent memory, storms in December 2020 and March 2017 will remain ahead of this one in terms of snow and overall impacts. One thing that makes this storm a bit more concerning that the โ€œaverageโ€ yearly winter storm is the deep cold. That will make treating the roads more difficult and will pose more of a risk when outside for any reason.”ย I would argue this was exactly on spot. It certainly wasn’t something I was using big inflammatory adjectives on.

Snow map redesign

Not only was I shooting for something accessible to the color blind and those with greyscale screens… but I purposefully chose blue colors to reduce the perceived hype surrounding snow amounts.

To assist me in the color scale of this redesign, I utilized some Artificial Intelligence (Claude, by Anthropic). It tried to tell me my decisions were boring and wouldn’t stand out! I had to point out that it would actually stand out because it would be different than the alarming colors everyone else uses. After pointing that out, it understood better.

No Claude, you don’t understand…

It is a fine balance, weighing the risks of a weather event and deciding how to communicate that with the public. Ultimately, I do not think that bright, anxiety inducing colors belong on a snow map for an area that sees as much snow as we get each year. My goal is information sharing… not generating clicks for a social media feed algorithm.

Update Frequency

There are some weather events, like severe thunderstorms, where the absolute latest information can be vital. Severe thunderstorms change by the minute, which is why I live-blog those events.

Winter storms, however, are slow moving and change slowly, relatively speaking.

Two and three days before the storm, I had a single post in the morning that focused mostly but notย exclusively on the storm. One day before, my morning post took the form of storm FAQs. I also had 1 special evening post dedicated to the snow map. It was a short post, and most of it was explaining the changes I made to the style of the map.

My policy is to produce one single snow map for an event. This prevents confusion in the forecast, especially since most other forecasts change multiple times a day or even hourly. These forecasts chase the latest model trends. My forecasts supersede the model noise and account for all of the information I have, which includes my knowledge and experience banks.

Post dozens of times, doing hourly live updates, making snow map after snow map… I believe that it all serves to hype up an event. I do not think this is a conscious decision others make, but more a product of our social-media driven information culture. Social media algorithms thrive on and therefore promote hype. If you don’t feed the algorithm, it leaves you behind. I know this is as fact, since my traffic from social media sources has cratered from over 50% of my traffic a couple years ago to roughly 20% of my traffic now.

 

Conclusions

In conclusion, since I’ve rambled on long enough now:

  • Taking my forecast as a whole, based on the impacts and context of the storm, I felt it was highly accurate and by reading my work, most people should have been well prepared but not overprepared for this event.
  • I am an independent meteorologist, and I approach weather reporting drastically different from the mainstream media, from social media, and from traditional methodologies in an effort to help people know what to actually expect from the weather.
  • This storm was a momentous learning opportunity when it comes to understanding how models deal with snow-liquid ratios, supplementing my experience and knowledge base with model biases in winter storms where temperatures are warmer and sleet may mix in.
  • It is amazing how complex the atmosphere is and how a difference of a couple degrees can totally change the outcome of a storm, all because the shape of the snow crystals changes.
  • It is equally awe-inspiring how perfectly everything has to come together in the atmosphere to produce the truly big storms… and how difficult it can be to get all those factors to line up.

Thank you for taking the time to read these reflections. I hope they give you a greater understanding and appreciation for the complexities of both the science of meteorology… and the sociology of communicating the weather to the public.

And a final tremendous thank you to all of my donors, who make my work possible. Thank you to the nearly 100 people that contributed to Finger Lakes Weather over the last few days, and the several hundred others who have support me with monthly donations or have supported me in the past.

Independent local media is so important, and I am blessed to have such a dedicated donor base to support me.

Side note: Please accept my apologies for any typos or grammatical errors. I’ve been working on this post for a couple of hours and my family is waiting at the dinner table for me to wrap it up… so I don’t have the time to do my usual proofreading!

 

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12 Responses

  1. Louise Henrie
    | Reply

    Thanks, Drew, I hardly ever see any post-event analysis; I enjoyed it. I do think we had at least a foot here in downtown Ithaca.

  2. Pete Readel
    | Reply

    Anyone who finds fault with what you produce and publish should be discounted and not taken seriously. Your efforts go far above those who swamp the media with exaggerated BS yet never substantiate their source nor admit they were wrong! Keep doing what you are doingโ€ฆ.always trying to get better!!

    • Meteorologist Drew Montreuil
      | Reply

      Thanks, Pete! And to be clear, I have gotten a grand total of ZERO negative comments… which considering the nature of the internet is pretty amazing. I love to tell people that I almost never get negative comments because the followers I have are such awesome people!! And you all are!

  3. Stu
    | Reply

    โ€œSensitive Dependence on Initial Conditions: Known as the butterfly effect, this principle dictates that a tiny, localized change in a system can result in large-scale differences in the outcome.โ€œ

    Excerpt from an article about โ€œchaos theoryโ€ which is perhaps of some relevance to understanding climate and weather and, by extension, forecasting and complexities around modeling.

    • Meteorologist Drew Montreuil
      | Reply

      Chaos theory is HUGE with weather models. Once you get out beyond 5-7 days, there are some crazy things that spin up on the models for exactly this reason… small errors early on that compound. Hype pages thrive on that and love posting the crazy images and stirring up the pot.

  4. Phil C
    | Reply

    Thanks for the post apocalyptic monster storm discussion. Very informative. and don’t worry Drew, I still think your the best!

  5. Elaine
    | Reply

    The snowflake structure situation is mostly common sense. I observed that when I woke up early Sunday morning and watched the snow fall under the street light. It was white on the ground, but didn’t really look like snowflakes up under the light where it was falling. So I did not expect to see as much accumulation as we are used to with such a rapid snowfall, and was not surprised that the inches on the ground in the end did not match expectations.
    My question though, is how do you get “snow” and accumulate several inches when it’s 5 degrees, or even 15 degrees? We used to say “it’s too cold to snow” with temps like that. I was watching a weather guy livestream on YouTube during the storm where someone down south reported to him that they were getting pouring rain at 18 degrees. How is that possible?
    And lastly, thank you, Drew, for the “blue colors” and no-hype reporting you give us. It is immensely helpful!!

    • Meteorologist Drew Montreuil
      | Reply

      Great questions, Elaine! So the ideal temperatures for snowflake growth are roughly about 0 to 10ยบ F. So the surface temperatures were spot on! But, that isn’t where the flakes were coming from, so it didn’t help that process much. If you look at the diagram, you can see the crystal sizes get much smaller in subzero temperatures. Cold air holds less moisture, so once you start getting below zero… there just isn’t much for the atmosphere to work with.

      As for the 18ยบ and rain… it is again all about the temperatures aloft. Warm air, being less dense, tends to ride up and over the cold air, trapping the cold at the surface. So, it may be 18ยบ at the surface, but 35ยบ a thousand feet up. That is a pretty extreme example but I’ve seen it before in other storm systems, too.

  6. Linda Orkin
    | Reply

    I found this discussion of snowflake structure fascinating and educational. I also appreciate the discussion of warmth in the atmosphere affecting density of snow and possibility of sleet when it seems way too cold for that. Great job. I did keep an eye on the size of flakes as you had mentioned the flakes would transition from small to big and fluffy. Which, which, as you say, didnโ€™t happen.

  7. jhholland
    | Reply

    Iโ€™m surprised you didnโ€™t have any readings of snow accumulation from Geneva!

    • Meteorologist Drew Montreuil
      | Reply

      I was also surprised that the NWS summaries had nothing from Ontario County whatsoever.

    • Pete Readel
      | Reply

      My โ€˜SWAGโ€™of snow fall, just at city/town line in Canandaigua would be 9 +/-โ€œ. Wind rearranged it so much that finding someplace unaffected would be difficult.

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