2024-2025 La Nina

[donsutherland1]

Five  thoughts on the upcoming colder pattern triggered by a developing EPO block and forecast AO-/PNA+ pattern:

1. The first half of December looks cold in much of the East. A one-week period with a temperature anomaly of 6°-10° below normal is plausible.

2. Initially snowfall options could be limited due to the source region of the air masses.  It remains to be seen whether the recent rainfall in the East and the upcoming storm to the Great Lakes region later this week were exceptions rather than the beginning of the end of the ongoing drought in the Northeast. Until a persistently wetter pattern emerges, my operating assumption remains that the drought will persist. That raises the bar for big snowfall events even as cold should be sufficient to allow for opportunities through at least the first half of December. The Great Lakes region and LES belts should be in good shape. For snowfall, I'd rather be in such cities as Chicago, Detroit, Buffalo and Toronto than Philadelphia, New York City, or Boston.

3. In most cases following exceptional November warmth and a colder first half of December, the second half of the month was not much warmer than normal. Therefore, the odds are now tilted toward a cooler than normal December in the eastern third of the U.S. including such cities as Philadelphia, New York City, Buffalo, Chicago, Detroit, and Indianapolis, among others. Toronto could also wind up colder than normal.

4. The long-range guidance might rush the break in the colder pattern. I suspect that timing closer to the winter solstice than mid-month might be more realistic for the onset of any pattern change.

5. These developments do not necessarily mean that winter won't be warmer than normal as per the seasonal guidance (the seasonal guidance usually does better with three month assessments than month-to-month ones). They do reinforce the idea that the coming winter won't be as abnormally warm as the last two winters have been.

A potential wildcard remains ENSO. The probability of a full-fledged La Niña event (tri-monthly average) has decreased. A neutral-cold outcome remains possible. The relative ENSO Index (RONI) will be consistent with La Niña.

[jm1220]

46 minutes ago, bluewave said:

Great post. If NYC can finish December at or below 36.0° which would be -3.1 or lower, then my guess is that they will at least have shot at the first colder than average winter in 10 years. While this won’t be a guarantee, 5 out of 7 winters since 1991 with a December at or below 36.0° went on to a colder winter using our new warmer 91-20 climate normals. So the departures below are set to the 91-20 normals where the NYC December average is 39.1° and the winter average is 36.2°

https://www.weather.gov/media/okx/Climate/CentralPark/nycnormals.pdf

All Decembers since 1991 in NYC at or below 36° since 1991 and the DJF average temperature set to the 91-10 departures 

2000……31.1°……DJF departure using 91-10 normals..-2.7

1995…….32.2°….DJF….-4.0

2010…….32.8°…DJF…..-3.4

2017….….35.0°…DJF…...0.0

2005….…35.3°…DJF….+1.1

2009…….35.9°…DJF….-2.4

2002….…36.0°…DJF….-5.0

 

All of those winters were also snowier than average in NYC. I’m quite confident if we can get the cold in here for more than glancing few day shots, we can get the snow to follow. We haven’t gotten out of these longer lasting cold patterns without at least one decent snow event in the last 20 years, and whatever we get in December is a big bonus for winter as a whole especially in a Nina. In every snowy Nina in NYC we had at least one half decent December snow event. If we get a decent offshore storm track it can definitely be snow in NYC even in early December with cold enough source air. 

[bluewave]

7 minutes ago, jm1220 said:

All of those winters were also snowier than average in NYC. I’m quite confident if we can get the cold in here for more than glancing few day shots, we can get the snow to follow. We haven’t gotten out of these longer lasting cold patterns without at least one decent snow event in the last 20 years, and whatever we get in December is a big bonus for winter as a whole especially in a Nina. In every snowy Nina in NYC we had at least one half decent December snow event. If we get a decent offshore storm track it can definitely be snow in NYC even in early December with cold enough source air. 

It looks like the Great Lakes should open for business first.

[michsnowfreak]

8 hours ago, snowman19 said:

Let’s be honest, this winter will be judged on how much snow it produces. 99% of winter lovers base a winter being great or a fail on how much snow it produces. Even if this winter turns out to be -5F from Dec-Mar, if it ends up dry with below average snowfall, people will call it a huge fail and say the winter sucked. Great winters are remembered for snow not cold

If I judge a winter on just total snowfall and not all other factors like cold and snowfall, then I guess I really need to give a lot more credit to the post-2015 era and less credit to the fact it was mild.

[michsnowfreak]

6 hours ago, roardog said:

I’ve noticed that 2M temps anomalies are usually too warm on the models already by day 10 or so. Just look at the euro weeklies. By the time you get to week three they usually show no below normal 2M temps anywhere in the world. lol. I think we should see what verifies first. Detroit will have no shot to reach 2002 level cold due to the Great Lakes but I think Chicago or Indianapolis has a shot to get some real mid winter type cold. 

It's looking like a LES/Clipper pattern. As we know, clippers are probably THE most difficult pattern to forecast more than a handful of days out. Always run the risk of cold and dry but what an unexpected early start to good winter weather. 

[GaWx]

 Natural gas opened up a whopping 7% this evening! With the ensembles still looking cold dominated, with no end yet in sight, and with NG having closed close to 7% off its highs on Fri, that actually isn’t a shock. So, now it is back up to near its Thu evening highs in the 3.50s.

[mitchnick]

Just now, GaWx said:

 Natural gas opened up a whopping 7% this evening! With the ensembles still looking cold dominated, with no end yet in sight, and with NG having closed close to 7% off its highs on Fri, that actually isn’t a shock. So, now it is back up to near its Fri highs in the 3.50s.

Larry, if modeling is anywhere close to being right, you should be seeing snow this year after a long and undeserved drought. Congrats.

[Stormchaserchuck1]

5 hours ago, GaWx said:

 Natural gas opened up a whopping 7% this evening! With the ensembles still looking cold dominated, with no end yet in sight, and with NG having closed close to 7% off its highs on Fri, that actually isn’t a shock. So, now it is back up to near its Thu evening highs in the 3.50s.

The long term spread with Crude Oil and Gasoline still has Natural Gas very low (spreading with these Energy's adjusts for inflation, and gives more data, going back before 1998).. It's in the top 10% lowest right now in this spread trade, even with a $3.5 price. For a -NAO Winter, we pretty much want Natural Gas to be at least $5-6. It is volatile, but if it gets stuck here I would still expect a warm Winter.  Still, it's cool to see the adjustments with long term modeling. Like I was saying last night, it's kind of surprising that long range models have remained cold, as that has not been the trend of the last 8 years. 

[bluewave]

5 hours ago, Stormchaserchuck1 said:

The long term spread with Crude Oil and Gasoline still has Natural Gas very low (spreading with these Energy's adjusts for inflation, and gives more data, going back before 1998).. It's in the top 10% lowest right now in this spread trade, even with a $3.5 price. For a -NAO Winter, we pretty much want Natural Gas to be at least $5-6. It is volatile, but if it gets stuck here I would still expect a warm Winter.  Still, it's cool to see the adjustments with long term modeling. Like I was saying last night, it's kind of surprising that long range models have remained cold, as that has not been the trend of the last 8 years. 

Probably due to the actual temperatures being cold but nothing too extreme for the first week of December. It’s still early in the season and we are starting from a very warm base state this fall. So it will take time to build more impressive cold. We usually have to wait until we get further into the winter like in 20-21 to generate a more impressive Arctic outbreak.
 

2021 record Arctic outbreak 

[snowman19]

Five  thoughts on the upcoming colder pattern triggered by a developing EPO block and forecast AO-/PNA+ pattern:
1. The first half of December looks cold in much of the East. A one-week period with a temperature anomaly of 6°-10° below normal is plausible.
2. Initially snowfall options could be limited due to the source region of the air masses.  It remains to be seen whether the recent rainfall in the East and the upcoming storm to the Great Lakes region later this week were exceptions rather than the beginning of the end of the ongoing drought in the Northeast. Until a persistently wetter pattern emerges, my operating assumption remains that the drought will persist. That raises the bar for big snowfall events even as cold should be sufficient to allow for opportunities through at least the first half of December. The Great Lakes region and LES belts should be in good shape. For snowfall, I'd rather be in such cities as Chicago, Detroit, Buffalo and Toronto than Philadelphia, New York City, or Boston.
3. In most cases following exceptional November warmth and a colder first half of December, the second half of the month was not much warmer than normal. Therefore, the odds are now tilted toward a cooler than normal December in the eastern third of the U.S. including such cities as Philadelphia, New York City, Buffalo, Chicago, Detroit, and Indianapolis, among others. Toronto could also wind up colder than normal.
4. The long-range guidance might rush the break in the colder pattern. I suspect that timing closer to the winter solstice than mid-month might be more realistic for the onset of any pattern change.
5. These developments do not necessarily mean that winter won't be warmer than normal as per the seasonal guidance (the seasonal guidance usually does better with three month assessments than month-to-month ones). They do reinforce the idea that the coming winter won't be as abnormally warm as the last two winters have been.
A potential wildcard remains ENSO. The probability of a full-fledged La Niña event (tri-monthly average) has decreased. A neutral-cold outcome remains possible. The relative ENSO Index (RONI) will be consistent with La Niña.

While the 1st half of December certainly looks chilly, no argument there, some of the bombastic claims on twitter right now that the pattern is locking in for winter are reckless to say the least. And I wonder if we start to see a more Niña like progression later on as the lag from this EWB catches up and the effects of the +AAM/WWB wave train wear off? 

[snowman19]

1 minute ago, bluewave said:

You can see the blending of the influences in the emerging model trends for the start of December. The +AAM spike introduced the high latitude blocking on the Pacific side. But we still have a lingering La Niña influence with the jet trying to split the ridge near Alaska between the -WPO and +PNA. What may happen is that one of these jet disturbances is strong enough to cause a relaxation of the pattern mid to late December. But if this neutral ENSO state continues into January, then we could get follow up Pacific blocking at that time which would help to erode the -PDO.

New run ridge slight lower -EPO ridging stronger jet

Old run more consolidated block weaker jet

 

 

 

 

This EWB is pretty significant and we are seeing 3.4 cooling anew. While a moderate/strong Niña is obviously completely off the table now, we may see a very weak Nina by the end of December. That has happened in the past with an ENSO cold-neutral in November (08-09). A cold-neutral at the very least is definitely assured. It’s going to be interesting to see what happens once the lag from this EWB catches up and the Nino like wave train blocking effects from the record WWB and AAM spike wear off

[snowman19]

@bluewave @donsutherland1 While a big curveball has been thrown with respect to the PAC, the stratospheric/SPV progression so far is not conducive to sustained AO/NAO blocking going into December, not that we need them to be with a PAC like that come early December

[bluewave]

38 minutes ago, snowman19 said:

This EWB is pretty significant and we are seeing 3.4 cooling anew. While a moderate/strong Niña is obviously completely off the table now, we may see a very weak Nina by the end of December. That has happened in the past with an ENSO cold-neutral in November (08-09). A cold-neutral at the very least is definitely assured. It’s going to be interesting to see what happens once the lag from this EWB catches up and the Nino like wave train blocking effects from the record WWB and AAM spike wear off

 

Yeah, if the +AAM influence starts to wane with a resurgent La Niña cooling and EWBs then we could see this pattern start to shift by mid-December as the Pacific Jet tries to intensify.

 

[40/70 Benchmark]

59 minutes ago, bluewave said:

You can see the blending of the influences in the emerging model trends for the start of December. The +AAM spike introduced the high latitude blocking on the Pacific side. But we still have a lingering La Niña influence with the jet trying to split the ridge near Alaska between the -WPO and +PNA. What may happen is that one of these jet disturbances is strong enough to cause a relaxation of the pattern mid to late December. But if this neutral ENSO state continues into January, then we could get follow up Pacific blocking at that time which would help to erode the -PDO.

New run ridge slight lower -EPO ridging stronger jet

Old run more consolidated block weaker jet

 

 

 

 

My idea of a big -WPO this season is certainly off to a good start.

[40/70 Benchmark]

54 minutes ago, snowman19 said:

This EWB is pretty significant and we are seeing 3.4 cooling anew. While a moderate/strong Niña is obviously completely off the table now, we may see a very weak Nina by the end of December. That has happened in the past with an ENSO cold-neutral in November (08-09). A cold-neutral at the very least is definitely assured. It’s going to be interesting to see what happens once the lag from this EWB catches up and the Nino like wave train blocking effects from the record WWB and AAM spike wear off

This is the scenario that I ultimately went with. Over the summer and early into the fall, if you followd my updates, I was advertising a weak to moderate La Nina with the 2008-2009 event as the floor. However, later in the fall it became clear that the "floor"scenario was becoming most likely.

[40/70 Benchmark]

24 minutes ago, bluewave said:

Yeah, if the +AAM influence starts to wane with a resurgent La Niña cooling and EWBs then we could see this pattern start to shift by mid-December as the Pacific Jet tries to intensify.

 

I am conflicted because as much as I love snow and winter, I also love being right and I need the pattern to go to shit to not end up with egg on my fact for the month of December. I still think we are quite mild by Christmas.

[40/70 Benchmark]

Jesus, I feel like @snowman19 

[donsutherland1]

Currently, 7 of the 9 statistical models and 9 of the 17 dynamical models are forecasting neutral ENSO conditions for the winter. Over the past 6 weeks, the Region 3.4 anomaly has averaged -0.23°C. The latest weekly figure for the week centered around November 20th is -0.1°C.

[40/70 Benchmark]

2 minutes ago, donsutherland1 said:

Currently, 7 of the 9 statistical models and 9 of the 17 dynamical models are forecasting neutral ENSO conditions for the winter. Over the past 6 weeks, the Region 3.4 anomaly has averaged -0.23°C. The latest weekly figure for the week centered around November 20th is -0.1°C.

Yea, I defintely gambled a bit and went against the consensus on ENSO.

[Allsnow]

 

[mitchnick]

10 minutes ago, donsutherland1 said:

Currently, 7 of the 9 statistical models and 9 of the 17 dynamical models are forecasting neutral ENSO conditions for the winter. Over the past 6 weeks, the Region 3.4 anomaly has averaged -0.23°C. The latest weekly figure for the week centered around November 20th is -0.1°C.

Cfs2 says there's a week of strong trades, then they become sketchy; not atypical of Climo when enso forcing peaks near Christmas. MEI rose to only -.5. Writing is certainly on the wall. Plus, you lose the the strengthening Niña influence and you open the door to re-energizing the ridge on the west coast like the end of last night's EPS. 

[snowman19]

20 minutes ago, 40/70 Benchmark said:

Yea, I defintely gambled a bit and went against the consensus on ENSO.

I still think there’s a chance we see a very weak La Niña in region 3.4 by late December. I’m also of the opinion that the current PAC is being entirely driven by the unexpected and very strong WWB. I do not believe we are seeing a full scale change in the PAC cycle like some others do. My guess is that we go back into a Niña-like PAC come late December or early January. We will have to wait until those +AAM effects wear off and the wave train changes before we can know that for sure. If I’m wrong, tear me apart. That said, I do believe a full scale PAC cycle change extra-tropically and tropically (ENSO, PDO, PMM, MJO, Indian Ocean, WPAC warm pool), will be in place for next winter and that change will begin this spring

[donsutherland1]

1 hour ago, snowman19 said:

While the 1st half of December certainly looks chilly, no argument there, some of the bombastic claims on twitter right now that the pattern is locking in for winter are reckless to say the least. And I wonder if we start to see a more Niña like progression later on as the lag from this EWB catches up and the effects of the +AAM/WWB wave train wear off? 

 

 

Even if the two-thirds or so of December is cold, there is no assurance that the pattern would lock in. Indeed, I suspect that it will begin to transition toward a milder pattern around the Solstice. Even very cold Decembers have been followed by generally mild conditions during the rest of the winter.

[40/70 Benchmark]

1 minute ago, snowman19 said:

I still think there’s a chance we see a very weak La Niña in region 3.4 by late December. I’m also of the opinion that the current PAC is being entirely driven by the unexpected and very strong WWB. I do not believe we are seeing a full scale change in the PAC cycle like some others do. My guess is that we go back into a Niña-like PAC come late December or early January. We will have to wait until those +AAM effects wear off and the wave train changes before we can know that for sure. If I’m wrong, tear me apart. That said, I do believe a full scale PAC cycle change extra-tropically and tropically (ENSO, PDO, PMM, Indian Ocean, WPAC warm pool), will be in place for next winter

Yes, I agree. We are seeing cracks in the foundation of this regime, at long last. Light at the end of the warm pool.

[uofmiami]

Webber has a thread this morning on what he thinks is driving pattern and it’s not the MJO:

 

[bluewave]

1 hour ago, 40/70 Benchmark said:

My idea of a big -WPO this season is certainly off to a good start.

It’s interesting that we may have both found our way to the Pacific blocking through different means. I was mentioning the mismatch potential back in October with the high amplitude MJO 5 leading to less MJO influence early on in December like we are seeing now.  But I wasn’t sure whether it would manifest in December as +PNA, -EPO, or -WPO. It’s good that we can use different approaches and come to a roughly similar conclusion of more blocking on the Pacific side to start December than recent years. The complicating factor I mentioned is that the mismatch  is occurring against a much weaker La Niña state than 2020, 2017, and 2010. So we may see more of a competing influence going foreword than those stronger La Niña years. It’s possible we may see a stronger MJO influence later on which would add another competing influence to the mix. It will be fun to see how it goes.

[40/70 Benchmark]

14 minutes ago, bluewave said:

It’s interesting that we may have both found our way to the Pacific blocking through different means. I was mentioning the mismatch potential back in October with the high amplitude MJO 5 leading to less MJO influence early on in December like we are seeing now.  But I wasn’t sure whether it would manifest in December as +PNA, -EPO, or -WPO. It’s good that we can use different approaches and come to a roughly similar conclusion of more blocking on the Pacific side to start December than recent years. The complicating factor I mentioned is that the mismatch  is occurring against a much weaker La Niña state than 2020, 2017, and 2010. So we may see more of a competing influence going foreword than those stronger La Niña years. It’s possible we may see a stronger MJO influence later on which would add another competing influence to the mix. It will be fun to see how it goes.

I incorporated your methodology to add confidence to the general mismatch idea, but I honed in on the WPO due to an area of anomalus warmth over the western Pacific.

I do think we will see more competing influences over the course of the season. I thought January would be the most wintry month, but perhaps it will be December, instead.

[Allsnow]

 

[Snowstorms]

4 hours ago, bluewave said:

You can see the blending of the influences in the emerging model trends for the start of December. The +AAM spike introduced the high latitude blocking on the Pacific side. But we still have a lingering La Niña influence with the jet trying to split the ridge near Alaska between the -WPO and +PNA. What may happen is that one of these jet disturbances is strong enough to cause a relaxation of the pattern mid to late December. But if this neutral ENSO state continues into January, then we could get follow up Pacific blocking at that time which would help to erode the -PDO.

New run ridge slight lower -EPO ridging stronger jet

Old run more consolidated block weaker jet

 

 

 

 

How is the most recent -PDO pattern (2019 - present) different than prior -PDO periods (i.e., 2005-2014 or 1960-1976) that featured more prominent cold winters? Perhaps the marine heatwave is having an effect on the PDO? 

[George001]

3 hours ago, snowman19 said:

@bluewave @donsutherland1 While a big curveball has been thrown with respect to the PAC, the stratospheric/SPV progression so far is not conducive to sustained AO/NAO blocking going into December, not that we need them to be with a PAC like that come early December
 

Often winter shows its hand early. We are seeing signs of both a somewhat resilient Alaskan ridge regime and a strong PV regime. It’s early, but if this continues into winter it would lead to a -EPO/+NAO look.