December 2025 OBS and Discussion

[MJO812]

[cleetussnow]

8 hours ago, Brian5671 said:

Not sure why cold matters on xmas-it's an indoor holiday.    Whether it's 12 or 56 you're sitting inside

What?  I don’t know where to start with this.

[jm1220]

23 minutes ago, MJO812 said:

Regular GFS squishes it like a bug, congrats-ish DC to Cape May. Didn’t even know there was an AI GFS.

[eduggs]

Far NW suburbs still on track for a possible C-2" tomorrow. Unlike last week which was more of a latitudinal gradient, this potential wintry event has a stronger elevational component.

I could see the top of Schunnemunk or Mt. Beacon getting an inch or two of snow while the Hudson River towns get zilch. Elevated NW NJ could get a little accumulation this time too.

[anthonymm]

Threat for Sunday looks impotent

[MJO812]

29 minutes ago, jm1220 said:

Regular GFS squishes it like a bug, congrats-ish DC to Cape May. Didn’t even know there was an AI GFS.

There is also a cmc para. AI is taking over everything. 

[eduggs]

Sunday isn't lost yet. The next day or so will likely resolve whether or not this is a potential wintry threat. The ICON, ECM-AI, GFS-AI, and GEFS support a possible snowstorm. The other guidance (UK, ECM, CMC, GEPS, EPS) aren't too far off.

[eduggs]

5 minutes ago, anthonymm said:

I expect consensus from the 0z's tonight that it will trend to a nothing burger. Central park could get just a T of snow for December if sunday doesn't materialize (we start torching around the 20th). That means go super low this winter (10"ish or less).

I get the pessimistic sentiment. I feel it too. But the reality is we just don't know how things will play out. Some of our best snowstorms seemingly came out of nowhere. And the positive surprises are more fun than fretting for a week about a modeled blizzard that might disappear. 

[MJO812]

AI Euro and euro are more amped

[Krs4Lfe]

7 minutes ago, anthonymm said:

I expect consensus from the 0z's tonight that it will trend to a nothing burger. Central park could get just a T of snow for December if sunday doesn't materialize (we start torching around the 20th). That means go super low this winter (10"ish or less).

 

Just now, eduggs said:

I get the pessimistic sentiment. I feel it too. But the reality is we just don't know how things will play out. Some of our best snowstorms seemingly came out of nowhere. And the positive surprises are more fun than fretting for a week about a modeled blizzard that might disappear. 

Unfortunately, in this fast flow pattern that has been dominant since 2019, I doubt storms will pop up out of nowhere. I think if there’s enough storminess around, one will come our way. 

[brooklynwx99]

this is why it’s sometimes not as simple as worse PNA -> weaker storm… the TPV is better oriented and allows the vort to curl more on the ECMWF

[NEG NAO]

33 minutes ago, MJO812 said:

There is also a cmc para. AI is taking over everything. 

pretty soon we won't even have to post on here AI will post for us knowing what we would say and when we would say it

[WeatherGeek2025]

8 minutes ago, NEG NAO said:

pretty soon we won't even have to post on here AI will post for us knowing what we would say and when we would say it

i don't think I want that!

[eduggs]

I'd take those ECM runs every time. Weekend, daytime snow. 8-12hr duration. Temps freezing or below. We pray.

[donsutherland1]

It will turn briefly milder tomorrow. Some rain showers are likely tomorrow night. Some wet snow showers could occur well north and west of New York City. It will then turn somewhat cooler for the remainder of the week, but the cold won't match today's chill.

Light precipitation is possible during the weekend, especially on Sunday.

The ongoing 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 WPO is forecast to become strongly negative beyond December 10th. That would likely contribute to the December 10-20 period also being colder to perhaps much colder than normal overall.

The probability that December 2025 will have a maximum monthly temperature below 60° is increasing. The last time that happened was in 2019 when the monthly high was 58°. If 2025 has a monthly high below 60°, that would be only the fifth such occurrence since 2000 (2003, 2004, 2005, and 2019 are the cases since 2000).

The ENSO Region 1+2 anomaly was -0.2°C and the Region 3.4 anomaly was -0.5°C for the week centered around December 3. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.27°C and the ENSO Region 3.4 anomaly has averaged -0.65°C. La Niña conditions will likely continue through at least mid-winter.

The SOI was +17.96 today. 

The preliminary Arctic Oscillation (AO) was -0.921 today. 

Based on sensitivity analysis applied to the latest guidance, there is an implied near 91% probability that New York City will have a cooler than normal December (1991-2020 normal). December will likely finish with a mean temperature near 34.1° (5.0° below normal). 

Supplemental Information: The projected mean would be 3.4° below the 1981-2010 normal monthly value. 

 

[qg_omega]

Historic torch is gearing up for second half of December, rubber band going to snap back hard

[MJO812]

14 minutes ago, qg_omega said:

Historic torch is gearing up for second half of December, rubber band going to snap back hard

Big troll 

[Krs4Lfe]

13 minutes ago, qg_omega said:

Historic torch is gearing up for second half of December, rubber band going to snap back hard

The only question remains: can we get 4” of snow at NYC before then? If we see a shutout for this month given how cold this month has been, that’s a big yikes 

[wishcast_hater]

17 minutes ago, qg_omega said:

Historic torch is gearing up for second half of December, rubber band going to snap back hard

Normal temps is not a torch.

[SnowGoose69]

Despite the change on the 18Z runs the ingredients for this are still in no man’s land.  This was stated by someone on the SNE forum too.   I think this will change about two times over in the next 36-48 hours.  There is even a risk for this thing to be a rainer honestly given the setup but I’d still lean towards a miss being the more likely fail 

[CPcantmeasuresnow]

1 hour ago, qg_omega said:

Historic torch is gearing up for second half of December, rubber band going to snap back hard

Maybe look up the definition of the word historic. I don't think you're using it correctly. 

[CPcantmeasuresnow]

3 hours ago, NEG NAO said:

pretty soon we won't even have to post on here AI will post for us knowing what we would say and when we would say it

Will it know about the damaging effects of the sun angle on snow accumulations?

[mob1]

ICON completely lost Sunday's wave 

[MJO812]

2 minutes ago, mob1 said:

ICON completely lost Sunday's wave 

Laughable changes

[eduggs]

FWIW, the RGEM at 84hr looks more like the 18z ICON than 0z. The RGEM has a more pronounced shortwave over the Dakotas and the PV is further north. The 0z ICON is much more suppressive with lower heights / the PV through the Lakes.

[SnowGoose69]

1 minute ago, eduggs said:

FWIW, the RGEM at 84hr looks more like the 18z ICON than 0z. The RGEM has a more pronounced shortwave over the Dakotas and the PV is further north. The 0z ICON is much more suppressive with lower heights / the PV through the Lakes.

Yeah was coming to say this.  Even the NAM was that way though at 84 the NAM is a mess anyway most times

[SHELEG]

Looks like the threat is on life support.

[TriPol]

5 hours ago, NEG NAO said:

pretty soon we won't even have to post on here AI will post for us knowing what we would say and when we would say it

From ChatGPT:
 

I promise I’m not here to take over your discussion board. Even if I can analyze model data or summarize runs, I can’t replace the personality, debates, instincts, or humor that all of you bring to these threads. Could I generate posts that sound like you? Sure. But should I? Absolutely not. The whole point of a forum like this is the human interpretation of chaotic data and the excitement that comes with it. I’m a tool, not a substitute for the community. Think of me as something that can help clarify a model run or answer a question, not something that will ever replace the fun of arguing about the CMC para at 1 AM.

The 18z, 384-hour GFS December special is a rite of passage. You know it’s fantasy. You know it will be gone by the next run. You know the cutoff low will become a pancake ridge by morning. And yet, there you are at 3:00 am, refreshing the panels like it’s the Super Bowl.

I may be an AI, but even I recognize the sacred tradition:
Long-range storms don’t have to be real to be meaningful. They just have to carry hope until the next run drops.

[SI Mailman]

3 hours ago, qg_omega said:

Historic torch is gearing up for second half of December, rubber band going to snap back hard

Unless it's in the 70's on Christmas Eve like 2015, it's not historic.  

[NEG NAO]

39 minutes ago, TriPol said:

From ChatGPT:
 

I promise I’m not here to take over your discussion board. Even if I can analyze model data or summarize runs, I can’t replace the personality, debates, instincts, or humor that all of you bring to these threads. Could I generate posts that sound like you? Sure. But should I? Absolutely not. The whole point of a forum like this is the human interpretation of chaotic data and the excitement that comes with it. I’m a tool, not a substitute for the community. Think of me as something that can help clarify a model run or answer a question, not something that will ever replace the fun of arguing about the CMC para at 1 AM.

The 18z, 384-hour GFS December special is a rite of passage. You know it’s fantasy. You know it will be gone by the next run. You know the cutoff low will become a pancake ridge by morning. And yet, there you are at 3:00 am, refreshing the panels like it’s the Super Bowl.

I may be an AI, but even I recognize the sacred tradition:
Long-range storms don’t have to be real to be meaningful. They just have to carry hope until the next run drops.

From my Neg NAO - AI:

will it snow in new york city this weekend ?

 

 

 

 The perennial question that captures the imagination of every New Yorker during the winter months: "Will we get snow this weekend?" The prospect of a winter wonderland or a slushy mess always hangs in the balance, a fascinating interplay of atmospheric pressure, temperature gradients, and moisture content that keeps meteorologists on their toes.

Regarding this upcoming weekend, December 12-14, 2025, it appears that New York City does have a chance of seeing snow, particularly during the overnight hours of Friday and Saturday. It won't necessarily be a major winter storm, but rather the potential for light snow or flurries as a series of weather systems move through the region. 

Here is a detailed breakdown of the forecast for your weekend:

• Friday, December 12th: The day itself is expected to be mostly sunny with highs in the upper 30s. The chance for snow arrives Friday night, specifically after midnight, when a clipper low may bring light snow or flurries to the area. The National Weather Service (NWS) is indicating a 30% chance of this happening. This is often a fast-moving system with limited moisture, so significant accumulation is unlikely at this time.
• Saturday, December 13th: Saturday is forecast to be mostly cloudy, with highs in the lower 40s. The weekend's second chance for snow will come Saturday night, as another system approaches. The NWS mentions a chance of snow after midnight, and some guidance models are even suggesting the potential for a more substantial system at this point, which weather experts are closely monitoring.
• • Sunday, December 14th: A chance of snow continues into Sunday. Some reports indicate snow is possible on Sunday, with highs dropping into the low 30s. 

   

   

  The key takeaway here is that while snow is in the forecast, the current predictions suggest a higher likelihood of lighter, nuisance-type snow or flurries rather than a disruptive, heavy snowfall event at this time. The exact accumulation amounts are still uncertain and highly dependent on the precise track of these weak systems. It is worth noting that New York City on average receives its first measurable snowfall around December 13th, so these systems are arriving right on historical schedule. 

   

   

   

  It is important to remember that weather forecasting, especially concerning the exact type and amount of winter precipitation along the I-95 corridor, can be a delicate balance due to fluctuating temperatures that can turn snow into rain or vice versa. Forecasters use a variety of computer models and data to determine the most likely outcome, and predictions can be refined as the weekend approaches. 

  For the most up-to-date and highly localized information as the weekend draws nearer, you should consult official sources like the National Weather Service (NWS) website or the city's official NYC Severe Weather page. Currently, there are no active winter weather watches, warnings, or advisories for the immediate New York City area. 

  In conclusion, a definitive "yes" or "no" for a snow-covered weekend is difficult to state with absolute certainty right now, as the chances are present but not guaranteed. It's more of a "maybe, especially late at night." Prepare for the cold, as an Arctic air mass is settling in, but you likely won't need your heavy-duty snow shovel just yet. Keep an eye on those updated forecasts; they are the best tool for staying prepared in the ever-unpredictable world of New York weather! If you have any more questions about the specific temperatures or wind chills expected, please feel free to ask!