December 2025 OBS and Discussion

[wthrmn654]

Oh I sorry, I opened a can of worms with that question post I made earlier! 

[North and West]

can't wait for the nam to tuck a low south of li

What does this map show and mean? I paused my eating of crayons to try and learn something. TIA.


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[North and West]

Can't believe all the complaining here and some folks saying we will never have a return to several above average snowfall seasons in a row here - - once again look at  this history of NYC snowfall and try to explain it - we will return to above average snowfall seasons soon enough - its just that some of you younger folks have been spoiled by all of the  much above average seasons since 2000........without a long stretch of much below normal seasons 
monthlyseasonalsnowfall.pdf

I think another thing is that we all have both recency bias and the feeling that things were better and grander in our younger years - whether it’s winters, pop music, sports teams, movies, etc.


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[North and West]

In a warming climate we can get larger snowstorms which is what happened during 2010 to 2018. The main caveat was that we needed the dominant storm track to be colder to our southeast in order to realize the higher snowfall potential. With the northwest and warmer shift to the storm tracks since 2018-2019, we have resumed the long term downward trend in the snowfall setting all-time 7 year record lows for snowfall.
 

 

Thank you. Seems logical.


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[NittanyWx]

1 hour ago, bluewave said:

 

Since 1995-1996 we have had 15 La Niña winters as defined by the RONI index. 14 out of 15 of those winters followed a repeating pattern which has been common the last 30 years. EWR, NYC, and LGA December snowfall pattern repeated throughout the entire winter. The Decembers with under 4” of snowfall at those stations went on to below average seasonal snowfall. With the Decembers over 4” or snow featuring average to naive average snowfall. 

You might ask how can this work out over 90% of the time?  My guess is that La Ninas tend to show what they are capable of early on in the season. Plus as our climate has warmed it has lead to more repeating and persistent patterns. So I view this December to winter snowfall relationship more as a marker of a deeper underlying shared pattern  rather than something that is directly causing the outcome. 

What is misleading about showing the long term snowfall trend in NYC since the regular observations began in the late 1800s? As the long term climate has warmed, the snowfall has gone down.

There have been shorter term up trends like from the 80s to 10s against the long term decline.

Plus snowfall measurements prior to the 1980s would be higher if measurements were taken as frequently as we do today.They also substituted melted down snow gauge measurements at times like in 1888 blizzard which undercounted the higher ratios back in the much colder era.

So the actual downward trend line is steeper if we correct for the different way we measure snow now.

Yeah so for me to take any real value of this having meteorological significance I need to see statistical correlating variables, which is why I've done a lot of work around correlations and partial correlations involving ENSO states, rate of change involving the SOI, etc and found minimal forecast/predictability value for snowfall locally. 

I've been burned by threshold/relational things in the past (SAI being chief among them) and have since really been hesitant on overfitting data to find some grain of predictability to it.

[EastonSN+]

24 minutes ago, SnowGoose69 said:

Next winter may be telling, its TBD but if we have lets say a 0.6-1.2 El Nino and we continue to see the PDO sit more near -1 to like + 0.5 we really want to see some degree of slowing Pac flow/less -PNA etc...if we still see a heavily Nina type pattern even in that type of regime we may be in trouble or at least waiting 5-10 years til we see the Pac go back to a +PDO ERA

Even if this occurs, why cant it change in 5 years? I forgot the MET who stated it, however the MET on this forum stated that the warm pool is sliding east slowly which should change things.

 

[NorthShoreWx]

3 hours ago, NorthShoreWx said:

The trend line is misleading.  It compares the past couple of years to the 1800s.  What does that look like if you start the chart in 1980?

 

3 hours ago, bluewave said:

 

What is misleading about showing the long term snowfall trend in NYC since the regular observations began in the late 1800s? As the long term climate has warmed, the snowfall has gone down.

There have been shorter term up trends like from the 80s to 10s against the long term decline.

Plus snowfall measurements prior to the 1980s would be higher if measurements were taken as frequently as we do today.They also substituted melted down snow gauge measurements at times like in 1888 blizzard which undercounted the higher ratios back in the much colder era.

So the actual downward trend line is steeper if we correct for the different way we measure snow now.

This response is about my perception of the usefulness of that graph.

When I look at that data series, I see a series of ups and downs in an overall declining trend for much of the period, but that trend reversed in the past several decades.  This chart gives me no confidence to predict what comes next 

The most obvious answer about how it is misleading is that the straight line on the graph represents a non-linear series. If we were to start the data series at 1980, it would be an increasing trend, not decreasing. Another way to look at it is that if extrapolating the trend lines forward there is a high probability of it being wrong.

Anecdote: I literally ran a regression using the same data back in school in 1982 (using NYC snowfall 1870 - 1980).  I wish I still had the greenbar it was printed on; that would be a trip.  Extrapolating the line forward indicated that NYC snowfall was decreasing and would have fallen to zero prior to the present time.

Considering 1980 to 2025 to be a short term trend and 1869 to 2025 to be a long term trend is subjective.  Snowfall in the 1700s may have been higher than in the 1800s, but years prior to that may have been lower than it is now.  There was a lesser amount of warming prior to 1980, and snowfall changes in that period were more likely "natural variations", yet figure prominently in the existing trend line.

Personally, I don't know if snowfall is or isn't rising.  I am confident that winters have gotten warmer.

Warmer winters leading to less snowfall in our region seems intuitive, but so far we haven't seen any actual evidence.

Edit: I just found the old greenbar printout mentioned.  Damn, I saved a lot of old stuff.

[brooklynwx99]

with the GFS and CMC looking more amped and the ECMWF and AIFS largely holding serve, I think we're trending towards the first plowable snowfall of the year for the metro. let's give it a couple more days, but things are looking good

[RU848789]

Looks like thread time...

Edit: just saw the new thread...

[bluewave]

1 hour ago, NittanyWx said:

Yeah so for me to take any real value of this having meteorological significance I need to see statistical correlating variables, which is why I've done a lot of work around correlations and partial correlations involving ENSO states, rate of change involving the SOI, etc and found minimal forecast/predictability value for snowfall locally. 

I've been burned by threshold/relational things in the past (SAI being chief among them) and have since really been hesitant on overfitting data to find some grain of predictability to it.

This has nothing to do with the SAI. The most recent 30 year data reflecting the warmer climate leaves no doubt as to the relationship.

Back in the colder climate era the relationship was much weaker than it has become. Part of this is due to weather patterns becoming more repetitive in a warmer climate probably owing to local tropical SSTs resulting in non-linear convective temperature forcing thresholds being crossed.

I understand that the most extreme warming has only occurred over the last 15 to 30 years. So we have a new emergent climate state that is different from the previous colder era. 

We don’t have the luxury anymore of a relatively stable global temperature regime as was the case from 1880 through 1982. So you had a much longer period where there was only a small increase in temperatures. It gave us a 100 years of correlations to work out and use. 

I understand that you may have some hesitancy in using the newer correlations derived over the shorter period. But I have been using numerous relationships from this new and warmer period that have been serving me well. But it’s not a 100 year data set to draw from like we had back in the older and colder climate era.
 

 

[cleetussnow]

3 hours ago, NEG NAO said:

Can't believe all the complaining here and some folks saying we will never have a return to several above average snowfall seasons in a row here - - once again look at  this history of NYC snowfall and try to explain it - we will return to above average snowfall seasons soon enough - its just that some of you younger folks have been spoiled by all of the  much above average seasons since 2000........without a long stretch of much below normal seasons 

monthlyseasonalsnowfall.pdf

Nah dude.  Its so warm now it will never snow again.  Walking around in shorts and flip flops all the time drinking pina coladas.  Sun angle is a constant threat too. It never gets cold enough to snow.  Those days are behind us. You know, background state.  
 

oh wait…

[Brian5671]

If Pensacola and New Orleans can have a MECS/Blizzard we are quite a ways away from no snow around here...

[ForestHillWx]

10+ day maps should be weighed lightly, in either warm or cold directions, in my opinion. 

[bluewave]

2 hours ago, SnowGoose69 said:

winter may be telling, its TBD but if we have lets say a 0.6-1.2 El Nino and we continue to see the PDO sit more near -1 to like + 0.5 we really want to see some degree of slowing Pac flow/less -PNA etc...if we still see a heavily Nina type pattern even in that type of regime we may be in trouble or at least waiting 5-10 years til we see the Pac go back to a +PDO ERA

The greater issue is the rapid subsurface warming across the Western Pacific mid-latitudes. This resembles more of a shift rather than a function of the old PDO cycles that we have become familiar with in the past. The new subsurface and H300 PDO index does a better job reflecting the magnitude of the shift.  
 

https://www.cpc.ncep.noaa.gov/products/GODAS/ocean_briefing_gif/global_ocean_monitoring_current.pdf

 

[Roger Smith]

If history repeats, with the 1946 record highs for today, it is just one year and sixteen days to the monumental blizzard of 2026. 

[Picard]

Ripping snow out here (I'm outside Newton at work). Ground is recovered and the roads and sidewalks look to be accumulating some slush.

[wdrag]

Wantage 0.3" at 240P since SB around 150PM. 32.4aF down from a high of 35.2. We had sprinkles at 1025 AM. Driveway snow covered but treated roads just wet.

[North and West]

Ripping snow out here (I'm outside Newton at work). Ground is recovered and the roads and sidewalks look to be accumulating some slush.

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[bluewave]

2 hours ago, NorthShoreWx said:

Personally, I don't know if snowfall is or isn't rising.  I am confident that winters have gotten warmer.

Warmer winters leading to less snowfall in our region seems intuitive, but so far we haven't seen any actual evidence.

https://news.ucar.edu/14009/snowfall-measurement-flaky-history

 

But when we turn to snowstorms in the Northeast, or elsewhere in the U.S., there is an additional factor at work when comparing modern numbers with historical ones. Quite simply, our measuring techniques have changed, and we are not necessarily comparing apples to apples. In fact, the apparent trend toward bigger snowfalls is at least partially the result of new—and more accurate—ways of measuring snowfall totals. Climate studies carefully select a subset of stations with consistent snow records, or avoid the snowfall variable altogether.

 

Earlier in our weather history, the standard practice was to record snowfall amounts less frequently, such as every 12 or 24 hours, or even to take just one measurement of depth on the ground at the end of the storm.

You might think that one or two measurements per day should add up to pretty much the same as measurements taken every 6 hours during the storm. It’s a logical assumption, but you would be mistaken. Snow on the ground gets compacted as additional snow falls. Therefore, multiple measurements during a storm typically result in a higher total than if snowfall is derived from just one or two measurements per day.

That can make quite a significant difference. It turns out that it’s not uncommon for the snow on the ground at the end of a storm to be 15 to 20 percent less than the total that would be derived from multiple snowboard measurements.  As the cooperative climate observer for Boulder, Colorado, I examined the 15 biggest snowfalls of the last two decades, all measured at the NOAA campus in Boulder. The sum of the snowboard measurements averaged 17 percent greater than the maximum depth on the ground at the end of the storm. For a 20-inch snowfall, that would be a boost of 3.4 inches—enough to dethrone many close rivals on the top-10 snowstorm list that were not necessarily lesser storms!

Another common practice at the cooperative observing stations prior to 1950 did not involve measuring snow at all, but instead took the liquid derived from the snow and applied a 10:1 ratio (every inch of liquid equals ten inches of snow). This is no longer the official practice and has become increasingly less common since 1950. But it too introduces a potential low bias in historic snowfalls because in most parts of the country (and in the recent blizzard in the Northeast) one inch of liquid produces more than 10 inches of snow.

This means that many of the storms from the 1980s or earlier would probably appear in the record as bigger storms if the observers had used the currently accepted methodology. Now, for those of you northeasterners with aching backs from shoveling, I am not saying that your recent storm wasn’t big in places like Boston, Portland, or Long Island. But I am saying that some of the past greats—the February Blizzard of 1978, the Knickerbocker storm of January 1922, and the great Blizzard of March 1888—are probably underestimated.

So keep in mind when viewing those lists of snowy greats: the older ones are not directly comparable with those in recent decades. It’s not as bad as comparing apples to oranges, but it may be like comparing apples to crabapples.