2024-2025 La Nina

[Typhoon Tip]

4 minutes ago, 40/70 Benchmark said:

Its enhacing convection over the MC, which is congruent with cool ENSO forcing. This is why 2022-2023 featured one of the most powerful cool ENSO Walker Cells on record, despte only registering -1.0 ONI.

it's not driving the walker cells.  

[Stormchaserchuck1]

You'll find that October is the only month of the year that has an opposite correlation to the Winter's NAO state.. so it may be a backwards way of doing things, but if we are expecting a +nao Winter, I would look for a -NAO October. And because of what's been correlating globally, I would say watch out for a -PNA and maybe +EPO pattern in October too. 

[40/70 Benchmark]

3 minutes ago, Typhoon Tip said:

it's not driving the walker cells.  

I didn't say "drive".....it enhanced it.

[Stormchaserchuck1]

7 minutes ago, PhiEaglesfan712 said:

For 13-14, the pattern changed long before Sept/Oct. I think it changed some time in mid-July. I've never seen a summer all of a sudden turn from hot to cold in the middle like that one. But that was a very wet summer from start to finish. Of course, that was a sign of things to come.

We still had a very -PDO pattern in Sept 2013.. that's what I'm referring to. But when the pattern doesn't change in the Fall's of those -PDO's, it usually carries into the Winter.. SSTs are more secondary to the atmospheric pattern though. 

[Stormchaserchuck1]

9 minutes ago, Typhoon Tip said:

although we've been observing cryo supporting and/or snow achieving air masses in half of the octobers since 2010, despite the -pdo.   not sure these have extended down into the m/a.. but there's clearly been a shift toward buckling the patterns and sending cold anomalies under roll-over/ higher latitude u/a warm nodes and causing new england cold bursts earlier.   interesting. 

thing is, they're not like persistent.   they're in and out in 7 days, the month sometimes still end up above normal by a tick or two.

 

Interesting.. I mean in good Winter's, the pattern just goes crazy cold in the preceding Fall's. I think this was the case in 95-96, too.. Big time +PNA or -EPO. 

People have also done research making December a hot month for the following Winter.. this is more common sense stuff though, cold begets cold, warm begets warm. It seems to be intensified for the last 30 years though. 

[Typhoon Tip]

3 minutes ago, 40/70 Benchmark said:

I didn't say "drive".....it enhanced it.

it's the other way around most likely.  but .. like i said, chicken or egg.   i suggest the egg is CC ... and just like the gom and adjacent sw atl basin is also an inferno, so to has this accumulated in the sw-w Pac.   it's just that the west pac is larger unobstructed expanse so is larger and more looming, but in either case...

[40/70 Benchmark]

Just now, Typhoon Tip said:

it's the other way around most likely.  but .. like i said, chicken or egg.   i suggest the egg is CC ... and just like the gom and adjacent sw atl basin is also an inferno, so to has this accumulated in the sw-w Pac.   it's just that the west pac is larger unobstructed expanse so is larger and more looming, but in either case...

Fair enough....we generally agree.

[PhiEaglesfan712]

2021-22 analog if 2024-25 turns to an east-based la nina: 

 

As you can see, the classic one cold month and the rest warm in the Eastern US.

[Typhoon Tip]

4 minutes ago, Stormchaserchuck1 said:

Interesting.. I mean in good Winter's, the pattern just goes crazy cold in the preceding Fall's. I think this was the case in 95-96, too.. Big time +PNA or -EPO. 

People have also done research making December a hot month for the following Winter.. this is more common sense stuff though, cold begets cold, warm begets warm. It seems to be intensified for the last 30 years though. 

ah yes. the coveted 'front loaded' winter.    man, the last one of those ... Decembers of 2008 - 2010 ... ?  i think it's been that long.  mostly the winters have just been a game of breaking continuity

but these cold intrusions don't even seem to be connected to the winter basal state, which comes in later.   and when it does, it seems to lack l/w residence with quicker pattern turn overs, and also higher base velocities in the physical wind.

folks should read papers like this ( no you per se ...just in general) 

https://phys.org/news/2023-12-jet-stream-faster-climate.html

[Stormchaserchuck1]

1 minute ago, PhiEaglesfan712 said:

2021-22 analog if 2024-25 turns to an east-based la nina: 

We had a RNA block make it past +600dm in Dec 2021! Because of how we started seeing big RNA anomalies in Feb-March 2009, then it picked up over time in the same months, I'm thinking RNA-December is a new trend that is also picking up.. 

[40/70 Benchmark]

20 hours ago, Stormchaserchuck1 said:

We had a RNA block make it past +600dm in Dec 2021! Because of how we started seeing big RNA anomalies in Feb-March 2009, then it picked up over time in the same months, I'm thinking RNA-December is a new trend that is also picking up.. 

Would go along with the idea of a slightly distubred PV early on before it really consolidates.

[Stormchaserchuck1]

1 minute ago, Typhoon Tip said:

ah yes. the coveted 'front loaded' winter.    man, the last one of those ... Decembers of 2008 - 2010 ... ?  i think it's been that long.  mostly the winters have just been a game of breaking continuity

but these cold intrusions don't even seem to be connected to the winter basal state, which comes in later.   and when it does, it seems to lack l/w residence with quicker pattern turn overs, and also higher base velocities in the physical wind.

folks should read papers like this ( no you per se ...just in general) 

https://phys.org/news/2023-12-jet-stream-faster-climate.html

Yeah, I'm hopeful that we can get some -EPO this Winter. They usually don't last for more than a few days, but when we had -epo last Winter, Kansas City had a wind chill of -35F! It is definitely still possible to see big time Winter cold.. 

[snowman19]

Honestly, I think this winter is going to be a relatively easy one to predict, in fact, I think this is going to be one of the few easy ones, (i.e. 02-03) we’ve seen, without many question marks. The people on twitter who are saying that it’s “going to be a very hard one to predict” are the same people who look for excuses to predict a very cold and very snowy winter for the east coast every year. I’m reserving my final judgment for November because things can change of course and it’s foolish to make a winter forecast right now IMO. That said, I don’t expect very much at all in terms of the main global ‘players’ to change between now and November. I think this winter is already showing its hand pretty clearly

[so_whats_happening]

11 hours ago, snowman19 said:

I believe to have a significant climate effect it needs to be a tropical volcano that reaches the stratosphere with a VEI of “high-end” 5 or above. I defer to @Volcanic Winter

I have to agree with 40/70 here on this one. A volcanic eruption of magnitude is still of importance time of year plays probably the bigger role in how it translates into the cooler season. The reason why tropical volcanic eruptions are more talked about is it happens to really impact radiative properties more so than high latitude. High latitude I believe plays a larger effect in the hemispheric mode in which it occurs how quickly it impacts im sure is up for discussion.

Now how volatile this is classified is not known yet so that portion also is to be determined but it managed to reach stratospheric levels (especially with northern latitudes having a lower stratosphere typically).

This will be interesting to see if indeed High latitude eruptions do have this type of impact.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL092017

[snowman19]

6 minutes ago, so_whats_happening said:

I have to agree with 40/70 here on this one. A volcanic eruption of magnitude is still of importance time of year plays probably the bigger role in how it translates into the cooler season. The reason why tropical volcanic eruptions are more talked about is it happens to really impact radiative properties more so than high latitude. High latitude I believe plays a larger effect in the hemispheric mode in which it occurs how quickly it impacts im sure is up for discussion.

Now how volatile this is classified is not known yet so that portion also is to be determined but it managed to reach stratospheric levels (especially with northern latitudes having a lower stratosphere typically).

This will be interesting to see if indeed High latitude eruptions do have this type of impact.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL092017

Thanks. Never seen that article before

[so_whats_happening]

1 minute ago, snowman19 said:

Thanks. Never seen that article before

No worries now there is a true test that will come with this. In 2010 Iceland erupted quite explosively in March/April (it tamed down in May I believe) timeframe. This lead to a rather pronounced -NAO period but it was on the tail end of a low solar situation too. All the while that year also exhibiting a fairly decent -PDO pattern as well. Since it is August it looks likely to not have a solid impact on the atmospheric pattern for winter but maybe toward the tail end of winter things could potentially get interesting.

It will be fun to monitor to see if indeed this is a fact with high latitude eruptions. I feel I need to state this, it does not mean this winter turns out in that manner but it was rather interesting to see how similar the other factors were going into this year as to 2010/11. The missing buoy data is not presenting the subsurface all too well on TAO right now. 2010 seemed a bit further along than this year currently.

[snowman19]

8 hours ago, so_whats_happening said:

No worries now there is a true test that will come with this. In 2010 Iceland erupted quite explosively in March/April (it tamed down in May I believe) timeframe. This lead to a rather pronounced -NAO period but it was on the tail end of a low solar situation too. All the while that year also exhibiting a fairly decent -PDO pattern as well. Since it is August it looks likely to not have a solid impact on the atmospheric pattern for winter but maybe toward the tail end of winter things could potentially get interesting.

It will be fun to monitor to see if indeed this is a fact with high latitude eruptions. I feel I need to state this, it does not mean this winter turns out in that manner but it was rather interesting to see how similar the other factors were going into this year as to 2010/11. The missing buoy data is not presenting the subsurface all too well on TAO right now. 2010 seemed a bit further along than this year currently.

Definitely interesting. My guess is that 10-11 would have been way different had there been high solar flux/high geomag, in fact I feel very confident in that. That article is still informative though, thank you again, good read. Also wonder if the weaker +AMO and lack of a New Foundland warm pool played a role? 
 

These are the main factors I’m looking at going into this winter that IMO will be the main drivers and need to be monitored going into November: 1) High Solar/geomag 2) Weak La Niña (looking more likely to be central based), also will be very well coupled as evidenced by the MEI/strong Niña background state 3) -PDO 4) -PMM 5) +QBO (possibly a strong event) 6) ++AMO/New Foundland warm pool 7) -IOD 8) MJO, very likely to see phases 4-6 being dominant again given the SSTs, -IOD/Nina combo 9) Very low arctic sea ice; I believe it’s contributing to the predominant +NAO/+AO we’ve had in recent years 10) Any possible stratospheric effects from the April Ruang eruptions, although likely to be weak effects given they were only a cumulative VEI 5, 11) AGW

[bluewave]

6 hours ago, snowman19 said:

These are the main factors I’m looking at going into this winter that IMO will be the main drivers and need to be monitored going into November: 1) High Solar/geomag 2) Weak La Niña (looking more likely to be central based), also will be very well coupled as evidenced by the MEI/strong Niña background state 3) -PDO 4) -PMM 5) +QBO (possibly a strong event) 6) ++AMO/New Foundland warm pool 7) -IOD 8) MJO, very likely to see phases 4-6 being dominant again given the SSTs, -IOD/Nina combo 9) Very low arctic sea ice; I believe it’s contributing to the predominant +NAO/+AO we’ve had in recent years 10) Any possible stratospheric effects from the April Ruang eruptions, although likely to be weak effects given they were only a cumulative VEI 5, 11) AGW

This was one of the strongest La Niña 500 mb summer patterns that we have ever experienced. In our older climate, a La Niña summer 500 mb pattern featured a ridge near Japan and south of the Aleutians. The Atlantic usually had a ridge east of New England. These 3 ridges this summer were some of the strongest we have observed. If this had been the winter with such a strong ridge near the Aleutians and near the East Coast, then it would have been among the warmest on record. So this is telling is that unless we can get some version of mismatch like in January 2022, the winter is going to be very mild again. Probably have to wait until October for some clues to see how the October early MJO indicator evolves. 
 

 
If the winter ridges turn out as exaggerated as the summer, then it will be a very mild winter again. So we need a mismatch along the lines of Jan 2022 with the MJO 8 and more +PNA to counter it. Without pushback we end up with 22-23 warmth again.

[40/70 Benchmark]

19 hours ago, snowman19 said:

Honestly, I think this winter is going to be a relatively easy one to predict, in fact, I think this is going to be one of the few easy ones, (i.e. 02-03) we’ve seen, without many question marks. The people on twitter who are saying that it’s “going to be a very hard one to predict” are the same people who look for excuses to predict a very cold and very snowy winter for the east coast every year. I’m reserving my final judgment for November because things can change of course and it’s foolish to make a winter forecast right now IMO. That said, I don’t expect very much at all in terms of the main global ‘players’ to change between now and November. I think this winter is already showing its hand pretty clearly

Often the most difficult ones to predict end up being the ones perceived as being easy leading in because we are usually missing something. I think 2007-2008 and 2008-2009 are the pathways to better winter outcomes.

[snowman19]

39 minutes ago, 40/70 Benchmark said:

Often the most difficult ones to predict end up being the ones perceived as being easy leading in because we are usually missing something. I think 2007-2008 and 2008-2009 are the pathways to better winter outcomes.

IMO 17-18 was another easy one. It already tipped its hand by this point in time and very little changed that fall. The overall synoptic picture never stopped being a very favorable one from August on….

[40/70 Benchmark]

5 minutes ago, snowman19 said:

IMO 17-18 was another easy one. It already tipped its hand by this point in time and very little changed that fall. The overall synoptic picture never stopped being a very favorable one from August on….

Its definitely not going to be a picturesque H5 plot for NE winter aifionados...I think that is a given. ...but that doesn't mean we can't get some more unconventional means of winter weather delivery. Key will be poleward ridging and shape/orientation of PV, etc.

[40/70 Benchmark]

13 minutes ago, 40/70 Benchmark said:

Its definitely not going to be a picturesque H5 plot for NE winter aifionados...I think that is a given. ...but that doesn't mean we can't get some more unconventional means of winter weather delivery. Key will be poleward ridging and shape/orientation of PV, etc.

Obviously this will be easier to pull off with latitude. If you didn't go well in 2007 or 2008, then you can probably pack it in save for maybe a fluke event.

[michsnowfreak]

22 hours ago, Stormchaserchuck1 said:

Yeah, I'm hopeful that we can get some -EPO this Winter. They usually don't last for more than a few days, but when we had -epo last Winter, Kansas City had a wind chill of -35F! It is definitely still possible to see big time Winter cold.. 

Big wintertime cold is a given if a pattern works out. Anyone that doesnt realize that doesnt know the difference between weather and climate.

A few things Ive noted about winter time cold locally.

~The frequency of winters with below zero temps is relatively steady. About 75% of winter see below zero temps at Detroit, and near 100% in rural areas of SE MI

~From 2009-2019, 4 different winters saw temps of -13F or colder at DTW. Prior to 2009, the period of 4 years with those temps spanned 1982-2008.

~The coldest winter temps, which used to almost always happen on clear, calm cold snowcovered nights, now sometimes come with howling arctic winds creating much lower wind chills. Ive had wind chills of -30F or colder in 2014, 2015, 2019, 2022, 2024. Prior to 2014, Id guess 1994 was the last time it felt that cold.

[bluewave]

The La Niña background state is so strong that it’s actually creating easterly shear in the Atlantic. This is why the models are quiet for late August instead of very active which we usually see during La Ninas. So we’ll have to wait until September for our next period of tropical development.

https://michaelrlowry.substack.com/p/the-bell-has-rung-so-why-are-forecast

Too much of a good thing?

 

As regular readers of this newsletter know, wind shear – the change in wind direction or speed with altitude – is one of the big hurdles to tropical development. Typically it’s the strong winds at upper levels (30,000-40,000 feet) which blow from west to east (known as upper-level westerlies) through the deep tropical Atlantic and the Main Development Region or MDR that create most of the wind shear issues.

So when upper-level winds in the tropical Atlantic turn more east-to-west (easterly winds) and against the west-to-east grain, it usually helps to reduce wind shear, which in turn favors hurricane development. This is especially true during La Niña years like we’re experiencing and when rising air settles in over Africa and the North Indian Ocean as it has recently – a big upper-level disturbance we track across the tropics called the Madden Julian Oscillation or MJO.

The combination of La Niña with the part of the MJO that usually reduces wind shear would normally suggest a conducive period for development. However, the upper-level winds have switched so far out of the east that they’re creating easterly wind shear issues across the Atlantic, an unusual problem not often seen in the basin.

 

It means that the MJO will need to move to a less conducive phase to bring back the seasonal upper-level westerlies and tamp down on easterly shear issues plaguing the basin right now. The easterly shear is also worsened by the low-level westerly winds from the northward displaced ITCZ we discussed earlier.

The MJO naturally propagates eastward across the globe and extended range models are already showing the easterly shear issues abating toward the end of the month.

So when will activity pick back up?

 

Putting all the pieces together, it should be another week or two before the current impediments clear out.

 

It’s possible our next spurt of activity is delayed until the beginning of September, but we should see the transition as August comes to a close late next week.

Traditionally 70% of tropical activity, including most hurricane formations, happens from September onward. Still a long way to go in the game, but for now we’ll soak up the unforeseen late August lull.

[Typhoon Tip]

35 minutes ago, bluewave said:

The La Niña background state is so strong that it’s actually creating easterly shear in the Atlantic. This is why the models are quiet for late August instead of very active which we usually see during La Ninas. So we’ll have to wait until September for our next period of tropical development.

https://michaelrlowry.substack.com/p/the-bell-has-rung-so-why-are-forecast

Too much of a good thing?

 

As regular readers of this newsletter know, wind shear – the change in wind direction or speed with altitude – is one of the big hurdles to tropical development. Typically it’s the strong winds at upper levels (30,000-40,000 feet) which blow from west to east (known as upper-level westerlies) through the deep tropical Atlantic and the Main Development Region or MDR that create most of the wind shear issues.

So when upper-level winds in the tropical Atlantic turn more east-to-west (easterly winds) and against the west-to-east grain, it usually helps to reduce wind shear, which in turn favors hurricane development. This is especially true during La Niña years like we’re experiencing and when rising air settles in over Africa and the North Indian Ocean as it has recently – a big upper-level disturbance we track across the tropics called the Madden Julian Oscillation or MJO.

The combination of La Niña with the part of the MJO that usually reduces wind shear would normally suggest a conducive period for development. However, the upper-level winds have switched so far out of the east that they’re creating easterly wind shear issues across the Atlantic, an unusual problem not often seen in the basin.

 

It means that the MJO will need to move to a less conducive phase to bring back the seasonal upper-level westerlies and tamp down on easterly shear issues plaguing the basin right now. The easterly shear is also worsened by the low-level westerly winds from the northward displaced ITCZ we discussed earlier.

The MJO naturally propagates eastward across the globe and extended range models are already showing the easterly shear issues abating toward the end of the month.

So when will activity pick back up?

 

Putting all the pieces together, it should be another week or two before the current impediments clear out.

 

It’s possible our next spurt of activity is delayed until the beginning of September, but we should see the transition as August comes to a close late next week.

Traditionally 70% of tropical activity, including most hurricane formations, happens from September onward. Still a long way to go in the game, but for now we’ll soak up the unforeseen late August lull.

mmm  i'm willing to add that a dearth of viable tw may be related.   the identities of them over the intracontinental african region have been weakly looking to me, and the ejects off the typical sierra leone traffic routes have been down in numbers. 

 

[PhiEaglesfan712]

6 hours ago, snowman19 said:

IMO 17-18 was another easy one. It already tipped its hand by this point in time and very little changed that fall. The overall synoptic picture never stopped being a very favorable one from August on….

13-14 and 14-15 were more straightforward to me than 17-18. In 17-18, the record warm October threw me off. That one and a record warm February really skewed things.

 

[so_whats_happening]

5 hours ago, bluewave said:

The La Niña background state is so strong that it’s actually creating easterly shear in the Atlantic. This is why the models are quiet for late August instead of very active which we usually see during La Ninas. So we’ll have to wait until September for our next period of tropical development.

https://michaelrlowry.substack.com/p/the-bell-has-rung-so-why-are-forecast

Too much of a good thing?

 

As regular readers of this newsletter know, wind shear – the change in wind direction or speed with altitude – is one of the big hurdles to tropical development. Typically it’s the strong winds at upper levels (30,000-40,000 feet) which blow from west to east (known as upper-level westerlies) through the deep tropical Atlantic and the Main Development Region or MDR that create most of the wind shear issues.

So when upper-level winds in the tropical Atlantic turn more east-to-west (easterly winds) and against the west-to-east grain, it usually helps to reduce wind shear, which in turn favors hurricane development. This is especially true during La Niña years like we’re experiencing and when rising air settles in over Africa and the North Indian Ocean as it has recently – a big upper-level disturbance we track across the tropics called the Madden Julian Oscillation or MJO.

The combination of La Niña with the part of the MJO that usually reduces wind shear would normally suggest a conducive period for development. However, the upper-level winds have switched so far out of the east that they’re creating easterly wind shear issues across the Atlantic, an unusual problem not often seen in the basin.

 

It means that the MJO will need to move to a less conducive phase to bring back the seasonal upper-level westerlies and tamp down on easterly shear issues plaguing the basin right now. The easterly shear is also worsened by the low-level westerly winds from the northward displaced ITCZ we discussed earlier.

The MJO naturally propagates eastward across the globe and extended range models are already showing the easterly shear issues abating toward the end of the month.

So when will activity pick back up?

 

Putting all the pieces together, it should be another week or two before the current impediments clear out.

 

It’s possible our next spurt of activity is delayed until the beginning of September, but we should see the transition as August comes to a close late next week.

Traditionally 70% of tropical activity, including most hurricane formations, happens from September onward. Still a long way to go in the game, but for now we’ll soak up the unforeseen late August lull.

Almost every storm that has come from Africa this year has been flying through the MDR into either the SW Atlantic or Caribbean. Beryl being at such a low latitude going through flow at 20-30mph is impressive even for early in the season.

[michsnowfreak]

3 hours ago, PhiEaglesfan712 said:

13-14 and 14-15 were more straightforward to me than 17-18. In 17-18, the record warm October threw me off. That one and a record warm February really skewed things.

 

The Feb 2018 map is a more extreme example of the CPC forecast for this winter and sure enough Feb 18 saw a parade of winter storms in this area before the late month torch.

[bluewave]

11 hours ago, so_whats_happening said:

Almost every storm that has come from Africa this year has been flying through the MDR into either the SW Atlantic or Caribbean. Beryl being at such a low latitude going through flow at 20-30mph is impressive even for early in the season.

The MDR SSTs have come down a bit since Beryl but are still high relative to before 2023 which set the second.

 

[snowman19]

10 minutes ago, bluewave said:

The MDR SSTs have come down a bit since Beryl but are still high relative to before 2023 which set the second.

 

IMO the forecasts for 25-30 named storms are probably in peril