2024-2025 La Nina

[michsnowfreak]

4 hours ago, LibertyBell said:

2017-2018 was a wild but fun snow season.  We had the cold blizzard in the first week of January on the anniversary of January 1996 centered around 2 weeks of very cold weather and a mild February (but it still snowed for Valentines Day) and then 4 snow storms in March and then the one in April that snowed out the Yankees home opener.  I love those April snowstorms, because you enjoy them more knowing they are the last one for the season.

 

I would say 2017-18 was the most recent winter that pleased a majority of this forum. Great winter here. We have had several winter hang right around avg (+/- a few inches) but '17-18 was our last well above avg snow season. 

[LibertyBell]

12 minutes ago, michsnowfreak said:

Believe it or not I actually remember that about 1997-98 in NYC, that they got a 5" storm in late March. If im not mistaken it was a surprise as well. 1997-98 and 2001-02 were not good winters here but they had some fun times, esp 2001-02 had a few fun storms. The least snowy winter Ive lived thru was actually last winter, 2023-24, when I saw 21.4". DTW saw 23.5", technically 0.1" more than they saw in 1997-98, but in 97-98 I measured 27.2", so I go with 2023-24 as my least snowy winter (Im 41). Its VERY hard to go an entire snow season with under 20" here, which makes those aforementioned sub-20" winters 1930s-60s so remarkable. Again, the warmth was the problem in those winters of the 1930s-50s, but in the 1960s it was suppression. I would absolutely LOVE a CC tweaked version of 1960s winters!

2022-23 was the least snowiest winter here, so we beat you by one year haha.

seriously this decade has been the least snowiest one so far.

[michsnowfreak]

1 hour ago, LibertyBell said:

2022-23 was the least snowiest winter here, so we beat you by one year haha.

seriously this decade has been the least snowiest one so far.

As mild as it was 2022-23 did ok here for snowfall. You've definitely had it worse relative to climo, so obviously a change will be coming at some point. Hopefully sooner rather than later. 

[bluewave]

3 hours ago, Stormchaserchuck1 said:

Before this year, we had 44/52 Winter NAO months (DJFM) positive since Dec 2011.  16/16 of NAO >1.11 in a month during that time were all positive!  No NAO less than -1.11 since Dec 2011, including this year. 

Could be the reason.. I don't see why warmer Atlantic SSTs in general would favor +NAO.  I have seen studies where there's a big sea-level height difference in the Atlantic 2011-2022. 

 

 

With Winter 24-25, it's now 46/55 months +NAO. That's your answer. 

There are probably multiple factors contributing to the more +NAO winter trend and -NAO summer trend. 
 

 

 

[Stormchaserchuck1]

13 minutes ago, bluewave said:

There are probably multiple factors contributing to the more +NAO winter trend and -NAO summer trend. 

It's why the SE ridge is linking up though. Over Greenland and the Davis Strait you have a -AO, but further south over the N. Atlantic the NAO is usually positive.. we saw this, this year when the AO was -5. That +NAO is actually closer to us than the AO is, and it's making it easier for a mid latitude ridge to happen over the East Coast.  9 Winter months of negative NAO since Dec 2011, 14 years, is not a lot. And 16/16 months of >+1.11 NAO.  It's not because of global warming that we are seeing more SE ridge, it's the Atlantic SLP pattern, not always aligned with the AO. 

Summer is interesting because it has not been significantly hotter in the East. Until last year the differences in max highs were not that great. Good to see the NAO correlating there. 

[bluewave]

1 hour ago, Stormchaserchuck1 said:

It's why the SE ridge is linking up though. Over Greenland and the Davis Strait you have a -AO, but further south over the N. Atlantic the NAO is usually positive.. we saw this, this year when the AO was -5. That +NAO is actually closer to us than the AO is, and it's making it easier for a mid latitude ridge to happen over the East Coast.  9 Winter months of negative NAO since Dec 2011, 14 years, is not a lot. And 16/16 months of >+1.11 NAO. It's not because of global warming that we are seeing more SE ridge, it's the Atlantic SLP pattern. 

It hasn’t made a difference whether it was a -NAO or -AO during the 2020s. March 2023 was one of the most negative NAO months of the 2020s so far. We still got the Southeast Ridge link up which forced the storm on the 13 to 15th too far north for my area. So it turned into an higher elevation special. 
 

2023   1.25   0.92  -1.11 

 

[Stormchaserchuck1]

5 minutes ago, bluewave said:

It hasn’t made a difference whether it was a -NAO or -AO during the 2020s. March 2023 was one of the most negative NAO months of the 2020s so far. We still got the Southeast Ridge link up which forced the storm on the 13 to 15th too far north for my area. So it turned into an higher elevation special. 

2023   1.25   0.92  -1.11 

March 2023 was a rare pattern, December 2022 was too. I think for March '23 we had -EPO too. Anomalies happen, but most of the time it's true that the +NAO is flexing the SE ridge. 

[bluewave]

2 minutes ago, Stormchaserchuck1 said:

March 2023 was a rare pattern, December 2022 was too. I think for March '23 we had -EPO too. Anomalies happen, but most of the time it's true that the +NAO is flexing the SE ridge. 

Maybe the higher 500mb heights near the East Coast are influencing the location of the wave breaks which have been leading to the orientation of the -AO and -NAO blocks during the 2020s. 

[Stormchaserchuck1]

8 minutes ago, bluewave said:

Maybe the higher 500mb heights near the East Coast are influencing the location of the wave breaks which have been leading to the orientation of the -AO and -NAO blocks during the 2020s. 

Maybe in February and March something is happening. The last 2 January's have been pretty cold when -AO/-NAO. 

We've only had 6 -NAO months in the 2020s so far.. 3 of them higher than -0.30.. 4 of them higher than -0.52. 

[bluewave]

17 minutes ago, Stormchaserchuck1 said:

Maybe in February and March something is happening. The last 2 January's have been pretty cold under -NAO/-AO's. 

We've only had 6 -NAO months in the 2020s so far.. 3 of them higher than -0.31.. 4 of them higher than -0.52. 

Montana has been one of the small areas in North America with 4 top 10 coldest Februaries since 2018. So these Arctic outbreaks have been focusing in smaller geographic regions. In the old days the cold dropping down the Plains would spread out to the East Coast. Now the core of the cold stays in a narrower corridor closer to the Plains and Midwest.
 

Time Series Summary for Great Falls Area, MT (ThreadEx) - Month of Feb
Click column heading to sort ascending, click again to sort descending top 10 coldest Februaries since 1892

1	1936	-5.2	0
2	2019	-0.2	0
3	1922	9.0	0
4	1989	10.3	0
5	1899	11.0	0
6	2025	11.3	0
7	2018	11.8	0
8	2021	12.4	0
9	1975	13.1	0
10	1978	14.4	0

 

[Stormchaserchuck1]

Quote

Montana has been one of the small areas in North America with 4 top 10 coldest Februaries since 2018. So these Arctic outbreaks have been focusing in smaller geographic regions. In the old days the cold dropping down the Plains would spread out to the East Coast. Now it stays focused in a narrower corridor closer to the Plains and Midwest.

Because the NAO has been mostly positive. 

[bluewave]

8 minutes ago, Stormchaserchuck1 said:

Because the NAO has been mostly positive. 

The state of the NAO whether positive or negative doesn’t cause the Northern Hemisphere cold pool to get smaller like we have been seeing resulting in the limited area of these Arctic outbreaks.

 

[Stormchaserchuck1]

I mean, yeah the globe is warming, it gets warmer every year. But the specific phenomena are easily explained by global patterns. In this case, indices have not always been favorable for cold everywhere. We have done "moderate" for cold in the midst of a warming globe lol. +NAO has highest correlation on the East coast.. that is probably why it's hitting the Midwest harder, that and a more favorable Pacific pattern for there (-EPO, -PNA). 

If we start getting some sustained -NAO's, I bet the east coast will be cold. 

-32F in Nebraska and 8" of snow in Florida.. not some bad Winter maxes this year. 

[bluewave]

24 minutes ago, Stormchaserchuck1 said:

I mean, yeah the globe is warming, it gets warmer every year. But the specific phenomenon are easily explained by global patterns. In this case, indices have not always been favorable for cold everywhere. We have done "moderate" for cold in the midst of a warming globe lol. +NAO has highest correlation on the East coast.. that is probably why it's hitting the Midwest harder, that and a more favorable Pacific pattern for there (-EPO, -PNA). 

If we start getting some sustained -NAO's, I bet the east coast will be cold. 

-32F in Nebraska and 8" of snow in Florida.. not some bad Winter maxes this year. 

The specific phenomenon are strongly influenced by the global temperatures at any given time. This is why teleconnections which were cold in the 70s to early 90s haven’t been as cold anymore. Plus the coldest recent month in the Northeast was during one of the strongest +NAO winters on record in February 2015. January 2021 was the most negative 2020s winter NAO month and it was mild in the Northeast. So other teleconnections and patterns have a much bigger influence than the NAO in the Northeast.

[Stormchaserchuck1]

6 minutes ago, bluewave said:

The specific phenomenon are strongly influenced by the global temperatures at any given time. This is why teleconnections which were cold in the 70s to early 90s haven’t been as cold anymore. Plus the coldest recent month in the Northeast was during one of the strongest +NAO winters on record in February 2015. So other teleconnections and patterns have a much bigger influence than the NAO in the Northeast.

-EPO still works here. Dec '22 and March '23 the only real exceptions. +PNA still works here. Those patterns have though also been more rare since 1998, and especially 2016. So the 3 favorable for cold are hitting less often, these are either + or -. Actually I think this January was one of the rare -NAO/-EPO/+PNA

Hopefully the start of them hitting again.. although I disagree that Jan 15-Feb 10 was +PNA. High pressure prevailed in the N. Pacific then. So since the NAO has only been negative 8 Winter months since Dec 2011, the 3 have probably lined up never. 

[PhiEaglesfan712]

2 hours ago, Stormchaserchuck1 said:

Summer is interesting because it has not been significantly hotter in the East. Until last year the differences in max highs were not that great. Good to see the NAO correlating there. 

Still, we've only had 2 summers cooler than average since 2010 (namely 2014 and 2023). And 2023 was due to a historically cold June. Despite that, the JJA 2023 average was a tenth below average. If you use JAS 2023, it's above the historical summer average.

2014 was two-tenths below average. So, we really haven't had a cool summer in the East since 2009.

[bluewave]

8 minutes ago, Stormchaserchuck1 said:

-EPO still works here. Dec '22 and March '23 the only real exceptions. +PNA still works here. Those patterns have though also been more rare since 1998, and especially 2016. So the 3 favorable for cold are hitting less often. Actually I think this January was one of the rare -NAO/-EPO/+PNA

Hopefully the start of them hitting again.. although I disagree that Jan 15-Feb 10 was +PNA. High pressure prevailed in the N. Pacific then. So since the NAO has only been negative 8 Winter months since Dec 2011, the 3 have probably lined up never. 

We had a big divergence between the CPC PNA and the 500 mb PNA especially in February which had the classic 500 mb -PNA vortex in the PACNW even though CPC index was +PNA. I liked your old idea of creating custom 500mb indices. I think the divergence between the AO and NAO is less if we just used the 500 mb composites and didn’t use the CPC. My guess is the 500 mb NAO would be negative more often than we have been getting from the CPC. So the NAO and AO would align more at the 500 mb level.

[Stormchaserchuck1]

3 minutes ago, PhiEaglesfan712 said:

Still, we've only had 2 summers cooler than average since 2010 (namely 2014 and 2023). And 2023 was due to a historically cold June. Despite that, the JJA 2023 average was a tenth below average. If you use JAS 2023, it's above the historical summer average.

2014 was two-tenths below average. So, we really haven't had a cool summer in the East since 2009.

I'm just saying, higher frequency of -NAO's has kept it more moderate.. no anomalously unknown SE ridge here

[Stormchaserchuck1]

7 minutes ago, bluewave said:

We had a big divergence between the CPC PNA and the 500 mb PNA especially in February which had the classic 500 mb -PNA vortex in the PACNW even though CPC index was +PNA.

Yeah, and if you go back, Feb-March 2018-2024 had a most +H5 on record by almost 200% #2 in the historical dataset for a 7-year consecutive period covering 2 months, over the N. Pacific ocean -PNA region.. That is a warm pattern for the east. So many of the indices have been unfavorable for some time now.  We also had 5/6 +WPO Winter's before this one, and the 1 was Neutral.. so 6 in a row of neutral or positive... switch those things around and it's not nearly as bleak a picture as these more recent climate stats are making it out to be. 

[Stormchaserchuck1]

14 minutes ago, bluewave said:

I liked your old idea of creating custom 500mb indices. I think the divergence between the AO and NAO is less if we just used the 500 mb composites and didn’t use the CPC. My guess is the 500 mb NAO would be negative more often than we have been getting from the CPC. So the NAO and AO would align more at the 500 mb level.

Yeah, but the NAO is a North Atlantic pressure difference index. Between the Azores and ~Iceland. So a lot of these "west-based -NAO blocks" over the Davis Strait and Baffin Island really have nothing to do with the North Atlantic ocean.  But I said earlier, sometimes when these blocks are too far north, because we are south of 45N, there can be unfavorable troughs that form underneath of them at even a higher latitude than ours.. that is what happened when the -5 AO storm cut inland.. The -300dm at 45-50N in the N. Atlantic Ocean favored that inland track, and that was the closer and more anomalous (volatility/latitude) pattern to us. 

I agree that I have no idea what the CPC is seeing in their index states some of the time... this Winter was not #1 +PNA non-El Nino in 75 years lol. We would have been colder in the east. 

[bluewave]

11 minutes ago, Stormchaserchuck1 said:

Yeah, but the NAO is a North Atlantic pressure difference index. Between the Azores and ~Iceland. So a lot of these "west-based -NAO blocks" over the Davis Strait and Baffin Island really have nothing to do with the North Atlantic ocean.  But I said earlier, sometimes when these blocks are too far north, because we are south of 45N, there can be unfavorable troughs that form underneath of them at even a higher latitude than ours.. that is what happened when the -5 AO storm cut inland.. The -300dm at 45-50N in the N. Atlantic Ocean favored that inland track, and that was the closer and more anomalous (volatility/latitude) pattern to us. 

But January 2021 was our most negative NAO winter month of the 2020s so far both at 500 mb and the surface. And it was still a mild January in the Northeast. Caribou finished at +7.9 and had their 10th warmest January on record. So such a strong -NAO in an earlier era in January was much colder in the Northeast even if there was also a trough near the Pacific NW. 

 

 

[Stormchaserchuck1]

6 minutes ago, bluewave said:

But January 2021 was our most negative NAO winter month of the 2020s so far both at 500 mb and the surface. And it was still a mild January in the Northeast. Caribou finished at +7.9 and had their 10th warmest January on record. So such a strong -NAO in an earlier era in January was much colder in the Northeast even if there was also a trough near the Pacific NW. 

+EPO/+WPO/-PNA really hit hard there.  I think the Pacific has more effect.. we have started to cool down -NAO's/-AO's in the last 2 Winters though.. although we have this 70s day coming up with a 3 sigma -NAO block around March 10-11.  I think the majority of the time, the NAO state is correct as a cold/warm signal.. those correlation maps I posted input all data, so it has 1,000 data points going back to 1948, everything included. 

[LibertyBell]

12 hours ago, bluewave said:

There are probably multiple factors contributing to the more +NAO winter trend and -NAO summer trend. 
 

 

 

-NAO summer doesn't mean the summers would be cooler though -NAO can result in a blowtorch summer too.

It's really moreso that we have a -NAO in the spring.

 

[LibertyBell]

9 hours ago, Stormchaserchuck1 said:

I'm just saying, higher frequency of -NAO's has kept it more moderate.. no anomalously unknown SE ridge here

-NAO doesn't mean a cool summer, didn't 2010 have a -NAO?

[LibertyBell]

9 hours ago, PhiEaglesfan712 said:

Still, we've only had 2 summers cooler than average since 2010 (namely 2014 and 2023). And 2023 was due to a historically cold June. Despite that, the JJA 2023 average was a tenth below average. If you use JAS 2023, it's above the historical summer average.

2014 was two-tenths below average. So, we really haven't had a cool summer in the East since 2009.

our hottest summers were in the 90s and the early 00s though.  I don't think -NAO correlates to a cool summer either though.

 

[LibertyBell]

10 hours ago, Stormchaserchuck1 said:

I mean, yeah the globe is warming, it gets warmer every year. But the specific phenomena are easily explained by global patterns. In this case, indices have not always been favorable for cold everywhere. We have done "moderate" for cold in the midst of a warming globe lol. +NAO has highest correlation on the East coast.. that is probably why it's hitting the Midwest harder, that and a more favorable Pacific pattern for there (-EPO, -PNA). 

If we start getting some sustained -NAO's, I bet the east coast will be cold. 

-32F in Nebraska and 8" of snow in Florida.. not some bad Winter maxes this year. 

10" of snow in Florida and 12" near New Orleans lol

[LibertyBell]

10 hours ago, bluewave said:

The state of the NAO whether positive or negative doesn’t cause the Northern Hemisphere cold pool to get smaller like we have been seeing resulting in the limited area of these Arctic outbreaks.

 

aren't +NAO becoming much more common in the winter and -NAO are becoming much more common in the Spring? Larry showed some stats that back this up.

 

[bluewave]

9 hours ago, Stormchaserchuck1 said:

think the Pacific has more effect.

I agree with this. The much faster Northern Stream of the Pacific Jet since 18-19 is the primary reason that we had such low snowfall from Philly to Boston. Warmer overall winter temperatures and especially the warmer storm tracks. The warmer storm tracks have prevented us from having a snowy winter in a warmer pattern like we often got back during the mid to late 2010s. So we finally got a winter near with near average temperatures this year. But the best we could do is a reversion to the much lower recent 7 year mean for snowfall. So the Pacific overpowered what used to be colder and snowier teleconnections as recently as last decade. 
 

Reversion to the 7 year snowfall mean in 2025 from Philly to Boston

 

Monthly Total Snowfall for Philadelphia Area, PA (ThreadEx)
Click column heading to sort ascending, click again to sort descending.

Mean	T	0.5	1.0	4.4	4.0	0.6	0.0	10.5
2024-2025	0.0	T	0.3	4.6	3.2	0.0	M	8.1
2023-2024	0.0	T	T	8.0	3.2	0.0	0.0	11.2
2022-2023	T	0.0	T	T	0.3	T	0.0	0.3
2021-2022	0.0	0.0	T	12.1	0.4	0.4	0.0	12.9
2020-2021	0.0	0.0	6.6	3.0	14.3	0.0	0.0	23.9
2019-2020	0.0	T	0.1	0.2	T	0.0	0.0	0.3
2018-2019	0.0	3.6	0.3	2.6	6.6	4.0	0.0	17.1

 

Monthly Total Snowfall for New York-Central Park Area, NY (ThreadEx)
Click column heading to sort ascending, click again to sort descending.

Mean	0.0	0.9	2.3	3.7	6.4	1.6	T	14.9
2024-2025	0.0	0.0	2.8	3.0	7.1	0.0	M	12.9
2023-2024	0.0	T	T	2.3	5.2	T	0.0	7.5
2022-2023	0.0	0.0	T	T	2.2	0.1	0.0	2.3
2021-2022	0.0	T	0.2	15.3	2.0	0.4	0.0	17.9
2020-2021	0.0	0.0	10.5	2.1	26.0	T	0.0	38.6
2019-2020	0.0	0.0	2.5	2.3	T	T	T	4.8
2018-2019	0.0	6.4	T	1.1	2.6	10.4	0.0	20.5

 

Monthly Total Snowfall for Boston Area, MA (ThreadEx)
Click column heading to sort ascending, click again to sort descending.

Mean	0.6	0.0	4.6	10.2	8.7	2.4	0.2	26.6
2024-2025	0.0	0.0	5.7	8.2	14.2	0.0	M	28.1
2023-2024	0.0	T	0.2	9.0	0.5	T	0.1	9.8
2022-2023	0.0	T	1.0	6.9	3.6	0.9	0.0	12.4
2021-2022	0.0	T	0.4	36.2	15.3	2.1	T	54.0
2020-2021	4.3	T	13.0	5.8	15.3	0.1	0.1	38.6
2019-2020	0.0	T	11.5	3.1	0.5	T	0.7	15.8
2018-2019	0.0	0.1	0.1	2.1	11.6	13.5	T	27.4

[40/70 Benchmark]

10 hours ago, Stormchaserchuck1 said:

+EPO/+WPO/-PNA really hit hard there.  I think the Pacific has more effect.. we have started to cool down -NAO's/-AO's in the last 2 Winters though.. although we have this 70s day coming up with a 3 sigma -NAO block around March 10-11.  I think the majority of the time, the NAO state is correct as a cold/warm signal.. those correlation maps I posted input all data, so it has 1,000 data points going back to 1948, everything included. 

January 2021 was another month in which it didn't look bad on paper per the CPC PNA index, but any higher heights out west were off of the coast, so it was ineffective practically speaking.

[40/70 Benchmark]

1 hour ago, LibertyBell said:

aren't +NAO becoming much more common in the winter and -NAO are becoming much more common in the Spring? Larry showed some stats that back this up.

 

Yea, we need to be just about at solar min to have a prayer of a -NAO winter season per the calculation....although I know there are other more practical metrics, such as the Greenland blocking index that Chris prefers.

https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/gbi.mon.data

EDIT: Link doesn't seem to be working...perhaps Chris knows what is up with that...