December 2024

[Picard]

Woke up to about 3/4" of slush and a 2 hour delay.
What surprised me was more snow in Lafayette and Newton (about 3"), which actually sits at a lower elevation than me by a couple hundred feet.  Must have been some nice banding just off to my north and west, because it was definitely a noticeable difference and a lot more plowing.

[bluewave]

1 hour ago, Eduardo said:

NS-dominant patterns can work under some conditions, but not these.  I wish I could get as excited about this setup as some seem to be.  But, from what I see, this isn’t likely to deliver (let alone boost us over that magic 3” December threshold).

The NS has definitely been playing the spoiler more often than not since 2018-2019. From 2010 to 2018 it would usually relax enough allowing the southern stream more influence for great benchmark tracks. Now the northern stream either warms things too much or suppresses the southern stream. If this was before 2018-2019, then we would expect the guidance to converge on an advisory or warning level event for NYC next few days as we got closer. But the 12z guidance has a lot of moving parts with varying NS low positions and differing southern stream locations. Seems like a lot has to go right for more than a light event near NYC and the coast. 

[jm1220]

1 hour ago, bluewave said:

The NS has definitely been playing the spoiler more often than not since 2018-2019. From 2010 to 2018 it would usually relax enough allowing the southern stream more influence for great benchmark tracks. Now the northern stream either warms things too much or suppresses the southern stream. If this was before 2018-2019, then we would expect the guidance to converge on an advisory or warning level event for NYC next few days as we got closer. But the 12z guidance has a lot of moving parts with varying NS low positions and differing southern stream locations. Seems like a lot has to go right for more than a light event near NYC and the coast. 

A lot’s always had to go right for the coast to get significant snow, but the pieces/pattern were in place prior to 2018-19. The Pacific changed and that’s what ruined it more often than not. Once in a while the NAO can help us out but the Pacific’s always been the main driver. When we’re flooded with warm Pacific air on a roaring fast jet stream or we have a huge negative PNA not much else can help us. We’re not at the latitude where we can count on SWFE events or marginal events. 

[MANDA]

Looks like the usual in and out Arctic shot (about 60 hours worth before moderation commences) in the days before Christmas.  Looks like everyone has a different definition of what a "torch" is but it sure looks like a torch to me starting 12/27 or so and lasting through New Year's Day at least.  Canada looks to get flooded with Pacific air as does the lower 48 starting over the Rockies then working east once past Christmas.

[STORMANLI]

12z 24- hour precipitation totals very uniform around NYC/LI:

KEWR 0.49"

KNYC 0.50"

KJFK 0.49"

KLGA 0.50"

KISP  0.46"

And Commack 0.48"

[jm1220]

11 minutes ago, MANDA said:

Looks like the usual in and out Arctic shot (about 60 hours worth before moderation commences) in the days before Christmas.  Looks like everyone has a different definition of what a "torch" is but it sure looks like a torch to me starting 12/27 or so and lasting through New Year's Day at least.  Canada looks to get flooded with Pacific air as does the lower 48 starting over the Rockies then working east once past Christmas.

The trough is moving into the Gulf of Alaska which means the US/Canada get flooded with maritime air. As long as it stays there you can safely slam the blinds for any wintry weather. Depressing-I did have the one snowy overnight IMBY but nothing else happening in a Dec that might be below normal temp wise is depressing. Hopefully when the torch comes there's sunny weather. I'm perfectly fine with that if it won't snow. Wasted cold/dry to warm/wet is the worst and it happens over and over in these Nina/fast Pacific jet patterns. Get it the F out of here. 

[Brian5671]

2 minutes ago, jm1220 said:

The trough is moving into the Gulf of Alaska which means the US/Canada get flooded with maritime air. As long as it stays there you can safely slam the blinds for any wintry weather. Depressing-I did have the one snowy overnight IMBY but nothing else happening in a Dec that might be below normal temp wise is depressing. Hopefully when the torch comes there's sunny weather. I'm perfectly fine with that if it won't snow. Wasted cold/dry to warm/wet is the worst and it happens over and over in these Nina/fast Pacific jet patterns. Get it the F out of here. 

Will likely take longer to cool down Canada if all the cold air is scoured out too.  

[weathermedic]

23 minutes ago, STORMANLI said:

12z 24- hour precipitation totals very uniform around NYC/LI:

KEWR 0.49"

KNYC 0.50"

KJFK 0.49"

KLGA 0.50"

KISP  0.46"

And Commack 0.48"

.97 at my station since just before midnight last night.

[winterwx21]

38 minutes ago, MANDA said:

Looks like the usual in and out Arctic shot (about 60 hours worth before moderation commences) in the days before Christmas.  Looks like everyone has a different definition of what a "torch" is but it sure looks like a torch to me starting 12/27 or so and lasting through New Year's Day at least.  Canada looks to get flooded with Pacific air as does the lower 48 starting over the Rockies then working east once past Christmas.

Definitely looks like the coldest air of the season. I don't think it will make it out of the 20s here on Sunday for the first time this season. Too bad the Christmas to New Year's period looks very mild. Would've been nice for it to feel like the holidays and maybe see some snowflakes during the big holiday week, but it doesn't appear to be in the cards.

[NEG NAO]

1 hour ago, MANDA said:

Looks like the usual in and out Arctic shot (about 60 hours worth before moderation commences) in the days before Christmas.  Looks like everyone has a different definition of what a "torch" is but it sure looks like a torch to me starting 12/27 or so and lasting through New Year's Day at least.  Canada looks to get flooded with Pacific air as does the lower 48 starting over the Rockies then working east once past Christmas.

this is a torch ??plus on New Years day we are going back into a colder pattern plus things will change probably too far out

 

[eduggs]

Drove through the Hudson Highlands this morning and there was an impressive snowcover around the West Point area. It must have really pounded early this morning. It wouldn't surprise me if there were a few spots up there that got 5 or 6 inches of snow.

[Brian5671]

3 minutes ago, NEG NAO said:

this is a torch ??plus on New Years day we are going back into a colder pattern - maybe a couple degrees above normal

No snow potential=torch.  Not to mention most warmups overperform these days

[Snowshack]

31 minutes ago, NEG NAO said:

this is a torch ??plus on New Years day we are going back into a colder pattern plus things will change probably too far out

 

If you look at the anomaly map for that same time it sure looks like a torch.

[MANDA]

1 hour ago, NEG NAO said:

this is a torch ??plus on New Years day we are going back into a colder pattern plus things will change probably too far out

 

That is a one day snapshot at PERHAPS the end of the warm period.  Poor example of what is coming between Christmas and New Year's.

[lee59]

1.03 inches of rain here today, still drizzle

[lee59]

Good start to winter in many inland areas, numerous snow events and below normal temperatures. Below normal temps here on Long Island also but less than an inch of snow so far. Not unusual for us to miss out this time of year.

[lee59]

Looks like early next week has 20s in the day and single digits and teens at night everywhere.

[NEG NAO]

48 minutes ago, MANDA said:

That is a one day snapshot at PERHAPS the end of the warm period.  Poor example of what is coming between Christmas and New Year's.

amazing you have that time period which is 9 - 16 days away all figured out ! congrats !

[Brian5671]

53 minutes ago, lee59 said:

Good start to winter in many inland areas, numerous snow events and below normal temperatures. Below normal temps here on Long Island also but less than an inch of snow so far. Not unusual for us to miss out this time of year.

This reminds me a bit of some of the late 90's yrs here where we had all rain but Central New England and upstate NY did well.   Alot of cars driving around here this AM with snow on them (was all rain here)

[qg_omega]

2 hours ago, NEG NAO said:

this is a torch ??plus on New Years day we are going back into a colder pattern plus things will change probably too far out

 

Historic

[donsutherland1]

Areas well to the north and west of New York City saw some snow and freezing rain this morning as warmer air pushed northward. New York City and its nearby suburbs saw only rain. Milder air has now returned to the region.

The peak warmth will be shortlived. It will be unseasonably mild tomorrow with temperatures rising mainly into the upper 50s and perhaps even the lower 60s. Additional rain is likely, as well. Following the rain, it will again turn somewhat colder before a much sharper shot of cold arrives for during or after the next weekend. The potential exists for the temperature to fall into the teens for the first time this season in New York City.

Beyond that, the pattern will likely remain changeable through much of the rest of the month on account of a fast jet stream.  December will likely close with above normal temperatures and January will likely see at least its opening days turn out milder than normal.

In past days, an occasional run of the operational GFS showed a significant snowstorm from Washington, DC to New York City. However, the pattern makes such an event very unlikely for this region. Since 1950, there were 5 December snowstorms that brought 6" or more snow to all three of these cities. Four (80%) occurred with a PNA+/NAO- pattern. The NAO is forecast to be positive. In addition, three (60%) occurred when the MJO was in Phase 8, which is not likely over the next 10 days. Only the December 23-25, 1966 event produced 6" or more snow in all three cities with a positive NAO, but the AO was strongly negative (< -2.000), which is not likely during the next 10 days. In sum, the interior sections will be far more favored for an appreciable or perhaps greater snowfall than the Washington-Baltimore-Philadelphia-New York City area over the next 10 days. A smaller snowfall remains plausible. One possible light snowfall could occur late Friday into Saturday morning. Any accumulations would be minor in and around the New York City area.

The NAO fell to a preliminary -2.751 on September 24th (all-time September record: -2.371, September 12, 1971). That was the 9th lowest value on record. La Niña winters following September cases where the NAO fell to -1.900 or below featured a predominantly positive NAO. The most recent such winters were 2016-2017 and 2022-2023. The mean temperatures for those winters in New York City were 39.3° and 41.0° respectively. The 1991-2020 normal value is 36.2°. A warmer to much warmer than normal outcome is favored by the November run of the ECMWF for Winter 2024-2025.

The ENSO Region 1+2 anomaly was -0.2°C and the Region 3.4 anomaly was -0.6°C for the week centered around December 11. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.17°C and the ENSO Region 3.4 anomaly has averaged -0.27°C. Neutral ENSO conditions may still evolve into a La Niña event during the winter. Uncertainty as to whether a La Niña will actually develop continues to increase. Currently, 47% of dynamical models and 22% of the statistical models forecast the development of a La Niña.

The SOI was +7.21 today.

The preliminary Arctic Oscillation (AO) was +1.003 today.

Based on sensitivity analysis applied to the latest guidance, there is an implied 85% probability that New York City will have a colder than normal December (1991-2020 normal). December will likely finish with a mean temperature near 36.7° (2.4° below normal).

 

[Brian5671]

5 minutes ago, qg_omega said:

Historic

The later freeze over of Hudson's bay is noticeable on alot of these maps....

[snowman19]

6 minutes ago, qg_omega said:

Historic

If that’s correct, even if the PAC goes favorable for cross polar flow after NYD, it’s going to take AWHILE to rebuild arctic air in Canada 

[MANDA]

30 minutes ago, NEG NAO said:

amazing you have that time period which is 9 - 16 days away all figured out ! congrats !

Time will tell and we'll know soon enough.

[lee59]

39 minutes ago, Brian5671 said:

This reminds me a bit of some of the late 90's yrs here where we had all rain but Central New England and upstate NY did well.   Alot of cars driving around here this AM with snow on them (was all rain here)

Yes I remember having no snow on long Island during some of those winters in December but as soon as I crossed over one of the bridges it was like another world with some snow and plenty of piles of snow from earlier storms.

[Brian5671]

Miserable day here-rain gave way to sheet drizzle that continues temps in the low 40's

[steve392]

1 hour ago, Brian5671 said:

Miserable day here-rain gave way to sheet drizzle that continues temps in the low 40's

We had fog from the snow cover and a steady mist all day.  

[jm1220]

2 hours ago, Brian5671 said:

Miserable day here-rain gave way to sheet drizzle that continues temps in the low 40's

Sheet drizzle city here too. Tomorrow at least it should clear out before the next useless cold/dry wave that will warm right up for the next sheet drizzle city event. 

[MJO812]

3 hours ago, snowman19 said:

If that’s correct, even if the PAC goes favorable for cross polar flow after NYD, it’s going to take AWHILE to rebuild arctic air in Canada 

Alot of bad takes in this thread 

[psv88]

1 hour ago, jm1220 said:

Sheet drizzle city here too. Tomorrow at least it should clear out before the next useless cold/dry wave that will warm right up for the next sheet drizzle city event. 

Yea this weather is horrific. Make it end. My snowblower still in the back of my garage. Not even close to moving it to the front