2024-2025 La Nina

[bluewave]

One thing to note for the first week of December is that the 850 mb temperature departures are forecast to be colder than the 2m since the Northern Hemisphere snow cover is still near record lows and will need some time to catch up. 
 

 

[michsnowfreak]

49 minutes ago, 40/70 Benchmark said:

Sounds about right...any semblance of winter is always eradicated before the holiday.

White christmas on the east coast/new england this year lol. There is no possible meteorological explanation why those grinch storms always hit you at Christmas other than bad luck. Its bound to change. Our general White Christmas (1"+ snowcover) climo here is 50/50 and there's been no trend away from that in recent years.

[snowman19]

35 minutes ago, snowman19 said:

I don’t think the issue comes the 1st 2 weeks of December. The thing that would support the NAO and AO/NAM going very positive is the SPV. The SPV forecast to get extremely strong and cold on the models and “couple” with the troposphere. They also have it moving directly over the pole. *IF* that happens it may be a problem going into mid-December

 

 

 

 

Just to add to this SPV disco, if the MJO (4-6) forcing does start to exert itself and we go back to a La Niña/-PDO like atmosphere with a -PNA, as @Stormchaserchuck1 mused, at the same time of a potential coupled SPV forced +NAO/+AO, then yes, the pattern could get very mild. And as I discussed yesterday, there is a possibility we go Niña in region 3.4 by the end of December with a projected EWB next month. “Commodity weather” pointed out that there have been cold-neutral ENSO Novembers that have gone La Niña by the New Year in the past. I don’t know what to think right now after this total mismatch we’re seeing to start December TBH

[bluewave]

32 minutes ago, michsnowfreak said:

meteorological explanation why those grinch storms always hit you at Christmas other than bad luck. Its bound to change

The 2nd half of December has been warming at a faster rate than the 1st half around the Northeast spots like NYC over the last 30 years. Every year since 2011 there has been a warm up between the 17th and 25th going over 55°. So it would be quite an accomplishment if we got a relaxation of this pattern for even one year. 
 

December 17 to 25 maximum temperature NYC over 55° every year since 2011

 

Time Series Summary for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.

2023-12-25	62	0
2022-12-25	58	0
2021-12-25	60	0
2020-12-25	61	0
2019-12-25	57	0
2018-12-25	61	0
2017-12-25	55	0
2016-12-25	58	0
2015-12-25	72	0
2014-12-25	62	0
2013-12-25	71	0
2012-12-25	56	0
2011-12-25	62	0
2010-12-25	40	0

 

 

[40/70 Benchmark]

35 minutes ago, snowman19 said:

Just to add to this SPV disco, if the MJO (4-6) forcing does start to exert itself and we go back to a La Niña/-PDO like atmosphere with a -PNA, as @Stormchaserchuck1 mused, at the same time of a potential coupled SPV forced +NAO/+AO, then yes, the pattern could get very mild. And as I discussed yesterday, there is a possibility we go Niña in region 3.4 by the end of December with a projected EWB next month. “Commodity weather” pointed out that there have been cold-neutral ENSO Novembers that have gone La Niña by the New Year in the past. I don’t know what to think right now after this total mismatch we’re seeing to start December TBH

2008-2009 is one prominent example.

[GaWx]

Eric Webb discovered ABNA and that the -ABNA is driving the current/upcoming cold E US pattern. Anyone here knowledgeable about ABNA? It’s actually not a new index though we had previously never heard of it. Regardless, not having a daily forecast nor a monthly history of it makes it less useful to me though the DJF mean is shown on a graph in this Eric tweet:

 

[GaWx]

12Z GEFS is about as cold run overall as any prior run through day 11. But days 12-16 remain to be seen. Also, fwiw, it has a significant increase in members with a tropical cyclone in the W Caribbean next week….interesting.

 Edit: 12Z GEFS isn’t the coldest days 12-16 but it is still cold overall thus making the total run another cold one.

 12Z Euro: 15 day run is about as cold as any yet per my eyeballs with 4 Canadian highs including current one plunging down

[bluewave]

It will be interesting to see if we can get another round of Nino 1+2 warming in early December if a follow up WWB verifies near 120W like the GFS has.

 

 

[brooklynwx99]

my initial impression of late Nov into early Dec so far is that the persistently +AAM that's being forecasted combined with +EAMT event is extending the Pacific jet more than is typical of La Nina. extensions are often favorable for us, and I believe these factors are overriding the largely unfavorable MJO passage

this general pattern favors +EAMT into early Dec, allowing for a persistently extended Pacific jet that leads to an Aleutian trough. the MJO isn't a silver bullet, and i do think we're seeing a break in the typically strong MJO correlation. never been happier to be wrong about a forecast, let me tell you

[GaWx]

The 12Z EPS is about as cold as any through day 12 (Dec 4th). The rest of the run is a bit warmer than recent runs but is still cold overall along with reinforcing cold at the end (12/7). 

[Terpeast]

49 minutes ago, brooklynwx99 said:

 

 

 

 

I don't think I've seen an MJO RMM forecast that shows it dying into COD from the warm phases in the last few years. Usually it gets even stronger as it goes through the MC. I hope this is right.

[mitchnick]

51 minutes ago, GaWx said:

The 12Z EPS is about as cold as any through day 12 (Dec 4th). The rest of the run is a bit warmer than recent runs but is still cold overall along with reinforcing cold at the end (12/7). 

Climo is getting colder, so we're still good in absolute terms 15 days out.

[bluewave]

18 minutes ago, Terpeast said:

 

I don't think I've seen an MJO RMM forecast that shows it dying into COD from the warm phases in the last few years. Usually it gets even stronger as it goes through the MC. I hope this is right.

This October into early December MJO forecast is similar to 2020 which I mentioned with the high amplitude  MJO 5 both Octobers and weaker MJO 5 in December before going into the circle.