December 2023

[40/70 Benchmark]

Looks like some cold to start before a flip to mild for a couple of weeks, followed by a colder and stormier look towards the holidays. This excerpt is from last week's write up, but nothing has really changed.

 

Intensifying PV for the duration of November and into December before beginning to weaken in the general vicinity of the holidays through the new year.

 

This overall progression is generally consistent with the Eastern Mass Weather forecast H5 composite for the month of December.

 

December Forecast H5 Composite:

1951-2010:

 

 

 

 

 

1991-2020: 

What is very apparent is the consistency with the early season canonical El Niño appeal, which is not at all uncommon, but makes a White Christmas along the Atlantic coastal plane from Massachusetts points south fairly dubious. However, analog data implies that there is a window for a significant winter storm between Christmas and the New Year. The interior should be the focus, but that does not necessarily preclude the coastal plane from experiencing an early season snowfall.

 

 

And this reality is conveyed quite vividly by the December forecast temperature composite.

December 2023 Forecast Temps:

1951-2010:

 

The month should finish 1-3 degrees F above average across the Mid Atlantic and New England.

1991-2020:

 

While the month should finish mild in the mean, it will be fairly active and should not be completely void of winter weather for the NE coastal plane, as there should be transient spasmodic PNA flexes. In fact, snowfall may very well be above average for the month across the deep interior and northern New England, where ski resorts should benefit from a blend of coastal storms and southwest flow events.

 

December 2023 Forecast Precip Anomalies:

 

1951-2010:

 

 

 

 

 

1991-2020:

 

 

 

There will be undoubtedly a great deal of unrest from the contingent of self-proclaimed weather experts on social media who remain traumatized from what seems like a mult-decadal run of cool ENSO events. And while some of that residual lea Nina like atmospheric momentum will undoubtedly remain, rest assured that the wheels of change will be in motion by the new year. El Niño will continue its westward progression at the surface towards being better colocated with the central Pacific forcing as the polar stratosphere concurrently begins to warm. 

[40/70 Benchmark]

Some of the latest guidance:

[40/70 Benchmark]

I am optimistic for a White Christmas over the interior...in and up. However, certainly a possibility to the coast.

[40/70 Benchmark]

CFS almost looks a bit 12/07ish in Janauary...crappy pattern, but the vortex is really protruding southward.

[Go Kart Mozart]

If I ignore the amber colors and just look at the shape of the December pattern...I would expect a cooler result.

[MJO812]

Euro weeklies for December is pretty nice.

[ORH_wxman]

1 minute ago, MJO812 said:

Euro weeklies for December is pretty nice.

First week and last week are nice. Middle two weeks are meh…though some southern stream action may still produce a threat even if it’s not all that cold (see Dec 23, 1997 as an example)

[weatherwiz]

16 hours ago, ORH_wxman said:

First week and last week are nice. Middle two weeks are meh…though some southern stream action may still produce a threat even if it’s not all that cold (see Dec 23, 1997 as an example)

I'll take my chances with an active southern stream. The "cold" is just a relative term. Yeah I'm sure climo will still bite someone in the behind, but we don't need -10F departures either. Just get an active southern stream, storm track just a bit off the coast, and have favorable temperatures across southeast Canada to tap into. 

[brooklynwx99]

as the MJO cycles through phases 3 and 4, we'll see a relaxation in the pattern early-mid Dec... could get quite warm

[brooklynwx99]

it does shift back to 8-1-2 once into mid-late month... colder weather then ensues, most likely. this is assuming the VP is correct

[CoastalWx]

23 minutes ago, brooklynwx99 said:

it does shift back to 8-1-2 once into mid-late month... colder weather then ensues, most likely. this is assuming the VP is correct

Yep. Looks like after the 15-18th or so. Maybe post 20th to be safe.

[brooklynwx99]

1 minute ago, CoastalWx said:

Yep. Looks like after the 15-18th or so. Maybe post 20th to be safe.

the forcing gravitating towards the C Pac / western IO is very encouraging... those are the sweet spots. the shittier canonical EP Nino years had forcing in the E Pac, but that seems to get brushed off by the twitter geniuses

[brooklynwx99]

lmao the weenie from Kevin. i guess he's not a fan of MJO wave propagation. who knew

[ORH_wxman]

Seems like euro suite has a much weaker MJO wave than the GFS suite. Might be something to watch in how long/intense the thaw is…though their current progged patterns for 12/5ish are pretty similar. 

[SJonesWX]

1 minute ago, brooklynwx99 said:

lmao the weenie from Kevin. i guess he's not a fan of MJO wave propagation. who knew

you would have to tell him what that is, first.

[weatherwiz]

14 minutes ago, brooklynwx99 said:

the forcing gravitating towards the C Pac / western IO is very encouraging... those are the sweet spots. the shittier canonical EP Nino years had forcing in the E Pac, but that seems to get brushed off by the twitter geniuses

It is extremely encouraging. Definitely love to see that. Once we are able to shake the rising air over much of the CONUS as well (evident by that VP map) we should start to get a more active look...something beyond just frontal systems and frontal system induced lows.

[ORH_wxman]

Weeklies shifted noticeably colder for the week before Xmas 

[CoastalWx]

1 hour ago, ORH_wxman said:

Seems like euro suite has a much weaker MJO wave than the GFS suite. Might be something to watch in how long/intense the thaw is…though their current progged patterns for 12/5ish are pretty similar. 

I noticed that too. 

[brooklynwx99]

10 minutes ago, ORH_wxman said:

Weeklies shifted noticeably colder for the week before Xmas 

this pattern makes sense given the MJO progression. pretty awesome look here with split flow undercutting a -EPO

[CoastalWx]

We'd take that.

[weatherwiz]

Can't hate where that mean trough axis is

[brooklynwx99]

Just now, weatherwiz said:

Can't hate where that mean trough axis is

yeah, no more pesky SW trough BS. pure Nino SE trough

[40/70 Benchmark]

2 hours ago, brooklynwx99 said:

as the MJO cycles through phases 3 and 4, we'll see a relaxation in the pattern early-mid Dec... could get quite warm

That looks very similar to my December mean composite, but it should get mitigated by the cooler start and finish.

[weatherwiz]

3 minutes ago, brooklynwx99 said:

yeah, no more pesky SW trough BS. pure Nino SE trough

We need that big time. Past few years, even when we've seen some signs of a trough into the East there was always ridging hanging around just to or east...or the likelihood the trough axis would be too far west and we pump up heights in the East. That concern is gone with this look.

[40/70 Benchmark]

13 minutes ago, brooklynwx99 said:

this pattern makes sense given the MJO progression. pretty awesome look here with split flow undercutting a -EPO

Watch for a big holiday period event focused over interior...my analogs scream it. Should be first major of the season.

[brooklynwx99]

2 minutes ago, weatherwiz said:

We need that big time. Past few years, even when we've seen some signs of a trough into the East there was always ridging hanging around just to or east...or the likelihood the trough axis would be too far west and we pump up heights in the East. That concern is gone with this look.

just saying, if we do indeed get that look in late December, it's off to the races IMO. can't think of a moderate / strong / super Nino that had a good pattern early to not continue it later in the winter

the ones that started off with a good pattern were often prolific. 2002 and 2009 are the most prominent examples. of course, we will need to see if this is voodoo or not

[40/70 Benchmark]

Could be the best holiday period pattern since 2009 and 2010.

[40/70 Benchmark]

2 minutes ago, brooklynwx99 said:

just saying, if we do indeed get that look in late December, it's off to the races IMO. can't think of a moderate / strong / super Nino that had a good pattern early to not continue it later in the winter

This. We will know shortly which ENSO ideology is correct.

[40/70 Benchmark]

1 hour ago, brooklynwx99 said:

the forcing gravitating towards the C Pac / western IO is very encouraging... those are the sweet spots. the shittier canonical EP Nino years had forcing in the E Pac, but that seems to get brushed off by the twitter geniuses

Nope, the pre satelite era biases the MEI towards Modoki....see, this is why all of the most powerful MEI values were obtained in east-based, canonical events.

[weatherwiz]

3 minutes ago, brooklynwx99 said:

just saying, if we do indeed get that look in late December, it's off to the races IMO. can't think of a moderate / strong / super Nino that had a good pattern early to not continue it later in the winter

the ones that started off with a good pattern were often prolific. 2002 and 2009 are the most prominent examples. of course, we will need to see if this is voodoo or not

Agreed, I'm still feeling 1957-1958 vibes. The signals we're starting to see for December are quite encouraging. what I would really hate to see are signals of a strengthening and dominating PV, which nothing has really suggested. Obviously we'll see some seasonal strengthening, but if the PV fails to become established moving into or through first half of December...I expect blocking begins to set in and we're off to the races as we get a much more favorable VP over the CONUS.