December 2025 OBS and Discussion

[NorthShoreWx]

1 hour ago, donsutherland1 said:

Thank you. It seems that the formula dropped "T" rather than counting it as 0 on the spreadsheet. Mean: 3.5"; median: 2.0"

I have that problem with the excel files I maintain for my climate records.  For my monthly snowfall summary ( https://www.northshorewx.com/ClimateData/SmithtownDailySnowfall.pdf ) I have a 0 for months where there were traces so that the averages don't get messed up (excluding October and May where the average is 0). 

I keep sheets with the daily data including traces, but I can't calculate an average value for a given date (e.g., December 3) because of all the years that have a trace on that date.  As a result, the difference between the actual average seasonal snowfall and the sum of the daily averages for the season in excel is significant; 36.2" vs 41.0"

 

[coastalplainsnowman]

3 hours ago, Neblizzard said:

We may have to toss December 

Definitely.  January and the first three weeks of February as well.  Best chance right now is looking like February 22nd.  Not the morning, but the afternoon.  After that, with the sun angle there's no chance anyway.

[MANDA]

Do with it as you wish but WPC not enthused for much precip in any form over the next 7 days.

I.E. cold and dry.

That said any subtle change in the flow could allow for a northward drift in the precip shield to our south but seems a long shot attm.

[NJwx85]

What did the 12z Euro show for Friday?

[snowman19]

2 minutes ago, NJwx85 said:

What did the 12z Euro show for Friday?

Zip zero

[NJwx85]

6 minutes ago, snowman19 said:

Zip zero

What about for SE PA?

[bluewave]

23 minutes ago, snowman19 said:

Zip zero

Continuation of the Great Lakes cutter, I 78 to I-84 hugger rain-snow line, and suppressed Southern Stream storm tracks since 2018-2019. Very persistent over-amped Northern Stream of the Pacific Jet. Makes you wonder what it’s going to take to shift this pattern?

[anthonymm]

6 hours ago, forkyfork said:

too much pacific energy keeping the pna ridge flattened and ruining an otherwise great pattern 

Where have we seen the pacific ruining I95 snow chances before ? Oh wait.

[anthonymm]

6 hours ago, BxEngine said:

Hes one of the kids that posts pessimistic shit this way when it inevitably happens, he can claim victory and also be mentally prepared for the sadness that people feel when they dont get what they actually want. And if we happen to get snow they wont acknowledge the incorrect posts, just move on and enjoy their snow they wanted while being doubly excited because they were pessimistic. Freud would have a field day in this forum.   

You can claim to examine my psychology as much as you want but I'm sure you'd agree the smartest forecast one can do these days is aim low on I95 snow

[jm1220]

38 minutes ago, bluewave said:

Continuation of the Great Lakes cutter, I 78 to I-84 hugger rain-snow line, and suppressed Southern Stream storm tracks since 2018-2019. Very persistent over-amped Northern Stream of the Pacific Jet. Makes you wonder what it’s going to take to shift this pattern?

This past one at the surface had a good track but the high was booted out like no one’s business and the surface winds turned SE ahead of it at the coast. Also it was on the move so fast that the mid levels could not develop a CCB and wrap cold air in after the surface to mid levels were torched. Maybe in Feb with the coldest waters of the season and preexisting deep cold air mass this could’ve worked. 

[anthonymm]

40 minutes ago, bluewave said:

Continuation of the Great Lakes cutter, I 78 to I-84 hugger rain-snow line, and suppressed Southern Stream storm tracks since 2018-2019. Very persistent over-amped Northern Stream of the Pacific Jet. Makes you wonder what it’s going to take to shift this pattern?

Monster +PDO in a warm neutral/moderate nino. NYC's not seeing a KU till the pac jet is utterly defeated.

[Brian5671]

2 minutes ago, jm1220 said:

This past one at the surface had a good track but the high was booted out like no one’s business and the surface winds turned SE ahead of it at the coast. Also it was on the move so fast that the mid levels could not develop a CCB and wrap cold air in after the surface to mid levels were torched. Maybe in Feb with the coldest waters of the season and preexisting deep cold air mass this could’ve worked. 

A little blocking could work too to keep that high anchored in...

[Krs4Lfe]

12 minutes ago, anthonymm said:

Monster +PDO in a warm neutral/moderate nino. NYC's not seeing a KU till the pac jet is utterly defeated.

Unfortunately, that’s not going to happen until we see some sort of big-time retraction of the Pacific jet, but that would require this summer temperatures over the north Pacific to not be super warm like they have been for the past seven years which leads to this faster pacific jet along the boundary with a colder Eurasia. 

[Krs4Lfe]

2 hours ago, MANDA said:

Do with it as you wish but WPC not enthused for much precip in any form over the next 7 days.

I.E. cold and dry.

That said any subtle change in the flow could allow for a northward drift in the precip shield to our south but seems a long shot attm.

Like I’ve said in the past, it’s always good to see storms around the country in December but it seems like aside from the stormy start that just occurred. We will have the next 7 to 10 days of pretty much cold and dry over eastern and central US with nothing to show for it. Pre 2020 era, we would have ample snowstorms moving across the northern tier when you had such a cold weather pattern. But now everything ends up being suppressed and then when a storm amps up it ends up cutting or the southeast Ridge pushes it too far west for any of us to see the benefit. Welcome to the new normal.

[bluewave]

11 minutes ago, jm1220 said:

This past one at the surface had a good track but the high was booted out like no one’s business and the surface winds turned SE ahead of it at the coast. Also it was on the move so fast that the mid levels could not develop a CCB and wrap cold air in after the surface to mid levels were torched. Maybe in Feb with the coldest waters of the season and preexisting deep cold air mass this could’ve worked. 

The fast Pacific flow and lack of blocking didn’t allow the cold high to stay anchored over New England. The WAR flexed just enough so the thermal gradient got pushed north of NYC. So these features negated the usual colder influence we see with lows tracking south of Long Island. Plus the low was strung out on a N-S axis without enough deepening near the benchmark to allow the cold air to wrap in behind the storm.

[FPizz]

40 minutes ago, anthonymm said:

Monster +PDO in a warm neutral/moderate nino. NYC's not seeing a KU till the pac jet is utterly defeated.

Maybe stop looking for KU's 24/7?  We went through an unprecedented stretch and now people think we should get them every year. 

Some of the garbage calls here the past several weeks:

Strong PV

MJO was never making it past p7

Thanksgiving to opening of Dec would torch

December would be warm

Mid month warmup

Strong PV again

Xmas Torch

But yet they post away like they are always right and never say oops.  Typical narcissistic behavior.  

Eventually they will get something right, lol.  Snow is always hard to come by here.  It always takes a lot of things to come together correctly, even for small snowfalls.

 

[eduggs]

A few more models are picking up possible snow showers tomorrow. The norlun feature on Saturday is also picking up a little more support. I think either feature could surprise with an isolated C-1"... I think there's even a low chance (maybe <1 in 8) of someone picking up 2" on Saturday in a persistent band. Unlikely though but still fun to nowcast if it happens.

[Dark Star]

2 hours ago, jm1220 said:

This past one at the surface had a good track but the high was booted out like no one’s business and the surface winds turned SE ahead of it at the coast. Also it was on the move so fast that the mid levels could not develop a CCB and wrap cold air in after the surface to mid levels were torched. Maybe in Feb with the coldest waters of the season and preexisting deep cold air mass this could’ve worked. 

I didn't like the positioning of the high pressure system...

[EastonSN+]

1 hour ago, FPizz said:

Maybe stop looking for KU's 24/7?  We went through an unprecedented stretch and now people think we should get them every year. 

Some of the garbage calls here the past several weeks:

Strong PV

MJO was never making it past p7

Thanksgiving to opening of Dec would torch

December would be warm

Mid month warmup

Strong PV again

Xmas Torch

But yet they post away like they are always right and never say oops.  Typical narcissistic behavior.  

Eventually they will get something right, lol.  Snow is always hard to come by here.  It always takes a lot of things to come together correctly, even for small snowfalls.

 

Great post. I can only imagine the posts before 2000. I get it though, if most of my experience was from close to 2000 onwards I would probably feel the same.

[MJO812]

Some posters on here are so depressing. 

[Wannabehippie]

1 hour ago, eduggs said:

A few more models are picking up possible snow showers tomorrow. The norlun feature on Saturday is also picking up a little more support. I think either feature could surprise with an isolated C-1"... I think there's even a low chance (maybe <1 in 8) of someone picking up 2" on Saturday in a persistent band. Unlikely though but still fun to nowcast if it happens.

I don't see anything on the models giving anyone in the tristate area anything more than a possible snow shower or flurry tomorrow. 

[Roger Smith]

A workaround for calculating means with traces is to find the sum, and divide it by the number of years. (not =AVERAGE(A1:A30) but =SUM(A1:A30)/30 (for 30 years).  Easy peasy. Disclaimer, my excel program is 2007 vintage, and they may have "improved" that procedure out of existence. But I can add columns where I cannot average them. 

Also if you wanted to know how many traces there were in 156 years or however many, the procedure there is =COUNTIF(A1:A156,"T") (just saying A because I am Canadian, your data may be in column USA). Free laffs with this stats lesson. I used "T" in my example and not "Tr" or "trace" but use whatever form your traces actually show up, I have NYC data with T and Toronto data with Tr ... and I found that on average about 20 to 25 per cent of days have a trace report.   

[donsutherland1]

The coldest air mass so far this season will overspread the region tomorrow night. The cold front could touch off a few scattered snow flurries or snow showers. The temperature will tumble into the lower 20s by Friday morning in New York City. Many areas outside the City will see lows in the teens.

It now appears that the weekend will be cool but dry. 

A colder than normal pattern is in place. A prolonged stretch of below normal temperatures will likely continue into or through the second week of December. December 1-10 will be a solidly colder than normal period. The potential exists for the coldest first 10 days of December since at least 2007 (33.4°, 5th coldest December 1-10 since 2000).

The five coldest December 1-10 periods since 2000 were:

1. 30.6°, 2002
2. 32.2°, 2003
3. 32.4°, 2000
4. 33.1°, 2005
5. 33.4°, 2007

All 5 of these cases had measurable snowfall in Central Park.

The ENSO Region 1+2 anomaly was -0.1°C and the Region 3.4 anomaly was -0.6°C for the week centered around November 26. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.18°C and the ENSO Region 3.4 anomaly has averaged -0.67°C. La Niña conditions will likely continue through at least mid-winter.

The SOI was -28.49 today. 

The preliminary Arctic Oscillation (AO) was -0.144 today. 

 

[MANDA]

2 hours ago, donsutherland1 said:

The coldest air mass so far this season will overspread the region tomorrow night. The cold front could touch off a few scattered snow flurries or snow showers. The temperature will tumble into the lower 20s by Friday morning in New York City. Many areas outside the City will see lows in the teens.

It now appears that the weekend will be cool but dry. 

A colder than normal pattern is in place. A prolonged stretch of below normal temperatures will likely continue into or through the second week of December. December 1-10 will be a solidly colder than normal period. The potential exists for the coldest first 10 days of December since at least 2007 (33.4°, 5th coldest December 1-10 since 2000).

The five coldest December 1-10 periods since 2000 were:

1. 30.6°, 2002
2. 32.2°, 2003
3. 32.4°, 2000
4. 33.1°, 2005
5. 33.4°, 2007

All 5 of these cases had measurable snowfall in Central Park.

The ENSO Region 1+2 anomaly was -0.1°C and the Region 3.4 anomaly was -0.6°C for the week centered around November 26. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.18°C and the ENSO Region 3.4 anomaly has averaged -0.67°C. La Niña conditions will likely continue through at least mid-winter.

The SOI was -28.49 today. 

The preliminary Arctic Oscillation (AO) was -0.144 today. 

 

Don-

Thanks as always for your always interesting and enlightening stats.

[NorthShoreWx]

3 hours ago, Roger Smith said:

A workaround for calculating means with traces is to find the sum, and divide it by the number of years. (not =AVERAGE(A1:A30) but =SUM(A1:A30)/30 (for 30 years).  Easy peasy. Disclaimer, my excel program is 2007 vintage, and they may have "improved" that procedure out of existence. But I can add columns where I cannot average them. 

Also if you wanted to know how many traces there were in 156 years or however many, the procedure there is =COUNTIF(A1:A156,"T") (just saying A because I am Canadian, your data may be in column USA). Free laffs with this stats lesson. I used "T" in my example and not "Tr" or "trace" but use whatever form your traces actually show up, I have NYC data with T and Toronto data with Tr ... and I found that on average about 20 to 25 per cent of days have a trace report.   

That would work, but then I would have to continually manually update formulas in many columns in multiple worksheets with the hardcoded number of years.  The summary, average and record sheets already require a fair amount of exactly that each year.  I'm sure there's a better (less manual) way but I always seem to have higher priorities.

I use the NY standard "T".  It also stands for Tariff 

 

[NorthShoreWx]

4 hours ago, Roger Smith said:

A workaround for calculating means with traces is to find the sum, and divide it by the number of years. (not =AVERAGE(A1:A30) but =SUM(A1:A30)/30 (for 30 years).  Easy peasy. Disclaimer, my excel program is 2007 vintage, and they may have "improved" that procedure out of existence. But I can add columns where I cannot average them. 

Also if you wanted to know how many traces there were in 156 years or however many, the procedure there is =COUNTIF(A1:A156,"T") (just saying A because I am Canadian, your data may be in column USA). Free laffs with this stats lesson. I used "T" in my example and not "Tr" or "trace" but use whatever form your traces actually show up, I have NYC data with T and Toronto data with Tr ... and I found that on average about 20 to 25 per cent of days have a trace report.   

I just remembered that I bared my soul on this 15 or 20 years ago on my website.  The page is still there.  Some of this will probably have changed (and the MS office versions definitely have), but it's a reasonable representation of my unsound methods:

https://www.northshorewx.com/Utilities/ClimateTemplates.html

[Wxoutlooksblog]

Our best chance to see some snow this month may be from a quick hitting Alberta Clipper or associated cold front. But of course we're talking light snow and nothing major. The trough is just too far east and the flow too flat. There isn't enough room or time for anything to really dig and slow down, gather moisture, and trigger a major winter storm as the maps look now. But it's early still and the models are not that good. Subtle adjustments and you just know they're going to happen could change things. We watch and wait. Most of my prior threat dates are now not so near misses.

WX/PT