2024-2025 La Nina

[Stormchaserchuck1]

We've had blocking over the NAO region.. I posted the image before, this is a pretty strong blocking signal for a 4-year period.. it's because within it we had 4-5 -NAO bouts. I don't know how or why the CPC calls that a +NAO, I've talked to Gawx about this before. Their calculations look silly compared to mean SLP. 

For the first time this year since 19-20, we've had negative anomalies over Greenland 

[Terpeast]

10 minutes ago, Stormchaserchuck1 said:

We've had blocking over the NAO region.. I posted the image before, this is a pretty strong blocking signal for a 4-year period.. it's because within it we had 4-5 -NAO bouts. I don't know how or why the CPC calls that a +NAO, I've talked to Gawx about this before. Their calculations look silly compared to mean SLP. 

For the first time this year since 19-20, we've had negative anomalies over Greenland 

Good point about looking at 500mb instead of raw index values (always a great reminder). 

Those 4-5 bouts of -NAO you mention, how many happened specifically in January or February?

Pretty sure it’s slim pickings other than Jan 2021. 

We did get a brief episode this January that resulted in 10 days of winter, but it got washed out by the rest of the month that brought about record warmth in the MA. 

[snowman19]

12 minutes ago, Stormchaserchuck1 said:

We've had blocking over the NAO region.. I posted the image before, this is a pretty strong blocking signal for a 4-year period.. it's because within it we had 4-5 -NAO bouts. I don't know how or why the CPC calls that a +NAO, I've talked to Gawx about this before. Their calculations look silly compared to mean SLP. 

For the first time this year since 19-20, we've had negative anomalies over Greenland 

Really since 19-20, we haven’t had an overall robust +NAO/+AO winter. Given the signals so far this year however, that may change this coming winter. It’s a rather ugly picture getting painted

[bluewave]

1 hour ago, Terpeast said:

Good point about looking at 500mb instead of raw index values (always a great reminder). 

Those 4-5 bouts of -NAO you mention, how many happened specifically in January or February?

Pretty sure it’s slim pickings other than Jan 2021. 

We did get a brief episode this January that resulted in 10 days of winter, but it got washed out by the rest of the month that brought about record warmth in the MA. 

I guess it can get a little confusing at times when people discuss blocking on the Atlantic side. Most blocks in recent years in this sector have been registering as -AOs rather than -NAOs. That’s why I like looking at the 500mb height anomalies to get a better read on the situation. In the past we would get the -NAO to fall in tandem with the -AO. But these days during the winters it has been more -AO dominant. Plus we have the more frequent south based blocks during the 2020s linking up with the Southeast ridge. While in the past this often wasn’t the case. Probably related to the record warming of the Gulf Stream and Atlantic.

[GaWx]

  There have now been 3 days in a row of large OISST Nino 3.4 anomaly drops. It has cooled a whopping 0.40C, the fastest since a similar 3 day cooling in early April and is now down to -0.23! The equivalent RONI snapshot is likely near -0.75 to -0.80.

[PhiEaglesfan712]

18 hours ago, George001 said:

ENSO neutral isn’t going to happen. It will be a La Niña

Yeah, there is close to zero potential for an el nino in either 2024-25 or 2025-26. Both years are likely to be la nina. I'll get back next summer after I take a look at the subsurface, and let you know if there is a potential for an el nino in 2026-27.

[Terpeast]

1 hour ago, bluewave said:

I guess it can get a little confusing at times when people discuss blocking on the Atlantic side. Most blocks in recent years in this sector have been registering as -AOs rather than -NAOs. That’s why I like looking at the 500mb height anomalies to get a better read on the situation. In the past we would get the -NAO to fall in tandem with the -AO. But these days during the winters it has been more -AO dominant. Plus we have the more frequent south based blocks during the 2020s linking up with the Southeast ridge. While in the past this often wasn’t the case. Probably related to the record warming of the Gulf Stream and Atlantic.

True, and also true about the south based blocks linking up with the SE ridge - that’s a pretty new phenomenon. 

I personally like numerical index values only because they’re easier to analyze in Excel or run a machine learning model on (one of my ongoing side projects btw). Not easy to do that with spatial 500mb maps, but it’s important to use those maps to validate any conclusion drawn from analysis using numerical indices. 

I’m also realizing that the NAO shouldn’t even be looked at in isolation, but in combination with the AO and other indices. The deviation of the AO from the NAO in and of itself should be a clue that something amiss is going on. 

[bluewave]

32 minutes ago, Terpeast said:

True, and also true about the south based blocks linking up with the SE ridge - that’s a pretty new phenomenon. 

I personally like numerical index values only because they’re easier to analyze in Excel or run a machine learning model on (one of my ongoing side projects btw). Not easy to do that with spatial 500mb maps, but it’s important to use those maps to validate any conclusion drawn from analysis using numerical indices. 

I’m also realizing that the NAO shouldn’t even be looked at in isolation, but in combination with the AO and other indices. The deviation of the AO from the NAO in and of itself should be a clue that something amiss is going on. 

I like the Greenland Blocking Index  which is like a combination of the AO and NAO. 
 

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

[GaWx]

3 minutes ago, bluewave said:

I like the Greenland Blocking Index  which is like a combination of the AO and NAO. 
 

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

And it looks like the sign for more blocking on this GBI is + rather than -.

[Stormchaserchuck1]

3 hours ago, snowman19 said:

Really since 19-20, we haven’t had an overall robust +NAO/+AO winter. Given the signals so far this year however, that may change this coming winter. It’s a rather ugly picture getting painted

You can sometimes get -NAO in the midst of shutout patterns. Look at Dec 2001 and Jan 1998 for example:

Two shutout Winters down here in the Mid Atlantic. Something that you have to consider about -NAO's is, although they have a 0.5 below normal temps correlation, they also have a 0.5 drier than average correlation. 

-NAO's have sometimes appeared during super-horrible patterns. 

[Stormchaserchuck1]

3 hours ago, Terpeast said:

Good point about looking at 500mb instead of raw index values (always a great reminder). 

Those 4-5 bouts of -NAO you mention, how many happened specifically in January or February?

Pretty sure it’s slim pickings other than Jan 2021. 

We did get a brief episode this January that resulted in 10 days of winter, but it got washed out by the rest of the month that brought about record warmth in the MA. 

Yeah, most of the -NAO periods have happened in December or March.. then when we had a -NAO in the middle of last Winter, we did have 2 snow events down in the Mid-Atlantic. I'd much rather look at 500mb maps though. The 2nd part of the CPCs range of negative anomalies 45N from the East coast to Africa is -NAO, but the PNA has been interfering lately... not that it isn't -NAO, just that downstream the Pacific ridge has been causing the mid latitudes in the Atlantic to stay warm (2nd 50% of their NAO calculation).  For practical purposes, I'm going to call the upper latitude pattern the NAO. 

[bluewave]

31 minutes ago, GaWx said:

And it looks like the sign for more blocking on this GBI is + rather than -.

Yeah, just like the PNA.

[BlizzardWx]

On 7/16/2024 at 7:22 PM, raindancewx said:

I'd like to see you change the color scheme by the North Pole. I doubt it is all below average? Otherwise this is a very useful product if you can update it easily. There are a lot of datasets for doing SST maps like this one. I would also add the baseline used. It looks like 1991-2020 to me but I can't prove it.

I would also add in the total (spatially weighted) SST warmth v. the baseline period as an index. Maybe the tropical warmth (23N-23S) too v. a baseline. I like the rectangular maps and automatically de-weight the lower/higher latitudes because the Earth is spherical. But a spherical representation would probably also do well.

Sorry I've been away for a while. This feature shows up on other websites like wxbell that use that dataset. It seems to occur in places where climatologically there should be ice but there currently is not so its an artifact of the dataset. I can cover it up with a  mask and it should be ok. But yes, I can also add the other areas you mentioned. It's no problem. 

[snowman19]

38 minutes ago, Stormchaserchuck1 said:

You can sometimes get -NAO in the midst of shutout patterns. Look at Dec 2001 and Jan 1998 for example:

Two shutout Winters down here in the Mid Atlantic. Something that you have to consider about -NAO's is, although they have a 0.5 below normal temps correlation, they also have a 0.5 drier than average correlation. 

-NAO's have sometimes appeared during super-horrible patterns. 

That is true. Back in Dec. 2001, JB was hemming and hawing that a huge winter was coming because of that -NAO Dec. That was his infamous “vodka cold” winter. Nothing but screaming zonal and semizonal flow off the PAC for months on end courtesy of the relentless high solar onslaught 

[GaWx]

1 hour ago, snowman19 said:

That is true. Back in Dec. 2001, JB was hemming and hawing that a huge winter was coming because of that -NAO Dec. That was his infamous “vodka cold” winter. Nothing but screaming zonal and semizonal flow off the PAC for months on end courtesy of the relentless high solar onslaught 

 Do you remember that during that winter (01-02) the prelude to the GFS (the MRF) had a terrible cold bias? It often showed intense and sometimes historic cold in week 2 and especially after day 10. This often mislead JB as he wouldn’t discount the cold bias. I was reading and posting about it at the old WWBB.

[so_whats_happening]

It looks like the models have finally decided we swing slightly (low amplitude on plots) through 7/8 before hitting 1. This is allowing the EPAC to finally get some tropical action. Bud was kind of a surprise little quick pop up and shows when the MJO just starts to enter the right areas it is going to produce. Carlotta looks reasonable still not sure yet about Daniel but it really depends on how quickly the MJO moves. Still looking like after this weekend the door opens up wide for the Atlantic. We may even see that sneaky wave become something as it gets to the islands by the weekend being close to the edge of uplift from the moving MJO wave.

So after we have just experienced Phase 5 for the past almost 2 weeks it will take some time for the mid latitudes to feel the effects of 7/8/1 as we move into August. Here is 5 in La Nada state to end July and as we head into August. We should start to see weakness/ troughing in the East come mid next week. After this and depending on the state of ENSO during that time we may have to start using Nina settings for the remainder of August in 7/8/1. Which actually hold troughing into much of the east but slowly push it westward in time to about GL region. This will open the door for the east coast/SE to potentially see some tropical activity push in as we go to mid to late month of August.

Hot the rest of this week into the weekend and then we should start to get closer to average toward middle of next week maybe finally increasing rainfall chances with it too. Looks like some fun times ahead.

[PhiEaglesfan712]

5 hours ago, GaWx said:

  There have now been 3 days in a row of large OISST Nino 3.4 anomaly drops. It has cooled a whopping 0.40C, the fastest since a similar 3 day cooling in early April and is now down to -0.23! The equivalent RONI snapshot is likely near -0.75 to -0.80.

This is almost eerily similar to 1998-99, which became a strong la nina. I really like 1998-99 and 2007-08 as my analogs. We'll probably get below average snowfall here in the mid-Atlantic, but there will be some spots that really get the snow.

[snowman19]

2 hours ago, GaWx said:

 Do you remember that during that winter (01-02) the prelude to the GFS (the MRF) had a terrible cold bias? It often showed intense and sometimes historic cold in week 2 and especially after day 10. This often mislead JB as he wouldn’t discount the cold bias. I was reading and posting about it at the old WWBB.

Yep the good old days of the GFS. It would show blizzards into June

[roardog]

4 hours ago, snowman19 said:

That is true. Back in Dec. 2001, JB was hemming and hawing that a huge winter was coming because of that -NAO Dec. That was his infamous “vodka cold” winter. Nothing but screaming zonal and semizonal flow off the PAC for months on end courtesy of the relentless high solar onslaught 

If I recall correctly there actually was a -NAO block in the second half of December 2001. Canada was still filled with relatively mild air though which only allowed the US to get near average cold. I remember there being a huge SW flow lake effect snow event which buried Buffalo since the water was mild from the warm November and first half of December. 

[Stormchaserchuck1]

15 hours ago, bluewave said:

Depends on the MJO. Frequent MJO 4-7s will get you -EPO/- PNAs at times when the Aleutian ridge becomes more poleward. A -EPO/-PNA is a warm pattern with a La Niña in the Northeast. This is when we hit 80° back in February 2018. In order to get it cold in the Northeast we need a -EPO +PNA like we got from December 2017 into early January 2018. But that required a MJO 8 pattern. 

So how would you predict the MJO in advance? You use SSTs west of Nino 4 (and ENSO of course)?

I've tried many things with the MJO and never came up with something that works from a good lead time. 

[michsnowfreak]

2 hours ago, PhiEaglesfan712 said:

This is almost eerily similar to 1998-99, which became a strong la nina. I really like 1998-99 and 2007-08 as my analogs. We'll probably get below average snowfall here in the mid-Atlantic, but there will be some spots that really get the snow.

Both were good snow seasons in the Great Lakes. 2007-08 wasn't terribly cold but was an excellent snow season, and 1998-99 was downright mild and short but had memorable blitzes of heavy snow/blizzards. @Stormchaserchuck1 has alluded to possible good snow setups in the Lakes/northern tier, and that fits well with many la nina induced patterns. Seems like a pretty negative attitude so far for the NE, but early on I'm liking the winter for the Great Lakes. 

[bluewave]

7 hours ago, Stormchaserchuck1 said:

So how would you predict the MJO in advance? You use SSTs west of Nino 4 (and ENSO of course)?

I've tried many things with the MJO and never came up with something that works from a good lead time. 

The first thing I do during a La Niña is see how amplified the MJO 5 is during October. For some reason the weaker La Ninas since 10-11 have all had weaker MJO 5s during October. This was followed by a stronger MJO 4-7 rebound in December. It’s why the weaker La Ninas since 10-11 have had warmer winters and the stronger La Ninas colder. Our best winters were 10-11, 17-18, and 20-21, which were stronger and colder ONIs and RONIs than the other grouped La Nias like 11-12, 16-17, and 22-23.  But every La Niña since 11-12 has been warmer than average. The magnitude of the warmth was stronger during the weaker La Ninas. The stronger La Ninas had stronger MJO 5s in October and weaker MJO 4-7s in December. This relationship doesn’t work for stronger coupled  El Niños or uncoupled El Niños since 15-16.

The long range guidance always seems underestimate  the MJO 4-7 forcing since 15-16 in any ENSO state coupled or uncoupled.The marine heatwaves in this area tend to focus the forcing here. Last winter also had a competing record marine heatwave in a MJO 2 leading to the colder pattern for a time out West in January. This increased to record MJO 4-7 forcing has resulted in an unprecedented 9 consecutive warm to record warm winters in a row for the Northeast.

[40/70 Benchmark]

3 hours ago, bluewave said:

The first thing I do during a La Niña is see how amplified the MJO 5 is during October. For some reason the weaker La Ninas since 10-11 have all had weaker MJO 5s during October. This was followed by a stronger MJO 4-7 rebound in December. It’s why the weaker La Ninas since 10-11 have had warmer winters and the stronger La Ninas colder. Our best winters were 10-11, 17-18, and 20-21, which were stronger and colder ONIs and RONIs than the other grouped La Nias like 11-12, 16-17, and 22-23.  But every La Niña since 11-12 has been warmer than average. The magnitude of the warmth was stronger during the weaker La Ninas. The stronger La Ninas had stronger MJO 5s in October and weaker MJO 4-7s in December. This relationship doesn’t work for stronger coupled  El Niños or uncoupled El Niños since 15-16.

The long range guidance always seems underestimate  the MJO 4-7 forcing since 15-16 in any ENSO state coupled or uncoupled.The marine heatwaves in this area tend to focus the forcing here. Last winter also had a competing record marine heatwave in a MJO 2 leading to the colder pattern for a time out West in January. This increased to record MJO 4-7 forcing has resulted in an unprecedented 9 consecutive warm to record warm winters in a row for the Northeast.

2017-2018 was a weak La Nina...close to moderate, but defintely not strong.

Not debating the point RE the MJO...

[snowman19]

10 hours ago, roardog said:

If I recall correctly there actually was a -NAO block in the second half of December 2001. Canada was still filled with relatively mild air though which only allowed the US to get near average cold. I remember there being a huge SW flow lake effect snow event which buried Buffalo since the water was mild from the warm November and first half of December. 

Yes there was -NAO blocking at that point but there was no arctic air to be had on our side of the pole. The UV was off the charts from September through late March, it heated the mid-latitude tropopause, shrunk and strengthened the SPV the AO went ++ and resulted in roaring zonal flow for months. The strong Niña background state, -PDO, etc. didn’t help matters either

[bluewave]

17 minutes ago, 40/70 Benchmark said:

2017-2018 was a weak La Nina...close to moderate, but defintely not strong.

The strength is relative to the other years in the multiyear La Niña event. 10-11 was stronger than 11-12. 17-18 was stronger than 16-17. And 20-21 was stronger than 21-22 and 22-23. So the 3 strongest years within the multiyear La Ninas were the coldest and snowiest. And the 3 weakest years of those groups relative to the others were the warmest and least snowy winters.

 

 

[40/70 Benchmark]

2 minutes ago, bluewave said:

The strength is relative to the other years in the multiyear La Niña event. 10-11 was stronger than 11-12. 17-18 was stronger than 16-17. And 20-21 was stronger than 21-22 and 22-23. So the 3 strongest years within the multiyear La Ninas were the closest and snowiest. And the 3 weakest years of those groups relative to the others were the warmest and least snowy winters.

 

 

Okay, I get it.

Interesting.....

[40/70 Benchmark]

Funny how we almost need to hope La Nina goes nuts this fall to have a "lull" period in the hostile forcing during the winter....almost akin to timing the intensity cycles in the tropics in the hope that RI can lead to an ERC pre landfall.

[snowman19]

[40/70 Benchmark]

Man, I would love to see Bluewave try the seasonal thing...he would be great at that. The again, maybe I wouldn't because it would make fall so much more depressing.

[40/70 Benchmark]

I'll joking aside, so far....this appears to the easiest winter outlook that I have done since 2014. Not much ambuguity overall IMO.