2024-2025 La Nina

[bluewave]

44 minutes ago, mitchnick said:

To determine whether they are "noisey", an undefined, subjective term I should add, we need to see forecasts from prior model runs since the Gefs have a new run every 6 hours. The difference between the 11/27 run RMM plots (it appears they calculate the plots off the 12z runs) and 11/28 plots may, in fact, be justified by a change in forecast by the model vs sssuming they are wrong. And considering model accuracy improves as we get closer to the target date, a model runs 24 hours later would likely be different and more accurate.

That said, I found Snowman's 'ing my post a better scientific explanation. Sorry. 

Happy Thanksgiving all. 

Noisy is a term frequently used in the CPC MJO discussions when dealing with the RMM plots. So there is nothing unusual about the term. The key for us won’t necessarily be a specific RMM index value but where the actual forcing is located. The VP anomaly  forecasts have been very steady in the MJO 5 for early December. Then they slowly propagate the wave closer to MJO 6 by mid-December. Forcing in that region in December usually results in a ridge developing near the East Coast. This is why the models have been showing more ridging near the East Coast in recent runs after early December. The only reason we are starting December colder than average is due to the +AAM spike boosting heights over the NPAC. Models have been indicating that this influence will gradually wane allowing more in the way of the Maritime Continent forcing influence to take over. 

[brooklynwx99]

I don’t think the MJO is having as much of an influence as it usually does, and long range models are having an issue with it by underestimating the Pacific jet given +AAM

the MJO is going through phase 4 right now, which is basically warm no matter what. however, long range models had a much warmer and more zonal pattern, correcting to a tall +PNA/-EPO. total fail in the Pacific

[brooklynwx99]

one of my gripes is seeing the MJO being used as a silver bullet, which has happens a ton lately. it’s a factor but it can definitely be ineffective at doing much when there are stronger forces. the lingering +AAM could be one of them

for the record, I do expect a relaxation in the pattern heading towards Christmas, but more of a gradient pattern moderation with cold in the Plains/Rockies rather than anything torchy. there’s little indication of that

[bluewave]

38 minutes ago, brooklynwx99 said:

one of my gripes is seeing the MJO being used as a silver bullet, which has happens a ton lately. it’s a factor but it can definitely be ineffective at doing much when there are stronger forces. the lingering +AAM could be one of them

for the record, I do expect a relaxation in the pattern heading towards Christmas, but more of a gradient pattern moderation with cold in the Plains/Rockies rather than anything torchy. there’s little indication of that

If go back a day and read the posts you will see that there is no mention of any silver bullet in regard to the forecast going forward. We were discussing the competing influences that we are seeing in the modeling. On one hand we had the strong +AAM rise leading to the blocking across the North Pacific. But the Pacific Jet is much stronger than when we had this pattern back in 13-14 and 14-15. So the upper low is much closer to Aleutians eroding the block from the west and displacing the ridge axis further east limiting the cold air production over North America relative to those years so far. As the influence to the +AAM begins to fade the continuing forcing near the Maritime Continent will start to have more influence leading to a moderation in the pattern by mid-December with more ridging near the East Coast. 

[brooklynwx99]

10 minutes ago, bluewave said:

If go back a day and read the posts you will see that there is no mention of any silver bullet in regard to the forecast going forward. We were discussing the competing influences that we are seeing in the modeling. On one hand we had the strong +AAM rise leading to the blocking across the North Pacific. But the Pacific Jet is much stronger than when we had this pattern back in 13-14 and 14-15. So the upper low is much closer to Aleutians eroding the block from the west and displacing the ridge axis further east limiting the cold air production over North America relative to those years so far. As the influence to the +AAM begins to fade the continuing forcing near the Maritime Continent will start to have more influence leading to a moderation in the pattern by mid-December with more ridging near the East Coast. 

I wasn’t specifically talking about you or the discussion in here… just the general vibe of LR forecasting over the last several years

[MJO812]

[leo2000]

1 hour ago, MJO812 said:

Too bad it can't come sooner I really really want a white Christmas for a change. 

[George001]

3 hours ago, brooklynwx99 said:

one of my gripes is seeing the MJO being used as a silver bullet, which has happens a ton lately. it’s a factor but it can definitely be ineffective at doing much when there are stronger forces. the lingering +AAM could be one of them

for the record, I do expect a relaxation in the pattern heading towards Christmas, but more of a gradient pattern moderation with cold in the Plains/Rockies rather than anything torchy. there’s little indication of that

I agree. The MJO is projected to be weak amplitude, not really a pattern driver like it has been in recent years. This year the projected pattern looks more similar to some of the early to mid 2010s rather than the post 2015 winters. 

[bluewave]

14 hours ago, George001 said:

I agree. The MJO is projected to be weak amplitude, not really a pattern driver like it has been in recent years. This year the projected pattern looks more similar to some of the early to mid 2010s rather than the post 2015 winters. 

You can’t go by the forecast amplitude that those RMM charts show. They often have the wrong amplitude beyond a few days out. It could be a function of the algos each individual model uses. The location and strength of the VP anomalies are usually a more reliable guide. Plus we have had RMM indices not far from the circle have an impact similar to amplitudes of a much higher range. When the MJO becomes the sole driver of the pattern at times, we can even get a well defined 500mb response when the RMM is near or in the circle with the VP anomalies more representative of the pattern.

So if the +AAM response begins to wane by mid to late December, even a little tropical forcing in the warmer phases can go a long way when it becomes more of a pattern driver. Our best bet for mid to late December is that the long range models are underestimating the +AAM response. And that the other tropical forcing like the MJO remains in background. 

Also remember that background tropical forcing in the warmer regions can have some influence on the storm tracks. Even when other features are stronger pattern drivers. We see this at times when a storm takes a cutter track and the cold comes in after the storm with Niña-like background forcing and too dominant of a northern stream.
 

[snowman19]

1 hour ago, bluewave said:

You can’t go by the forecast amplitude that those RMM charts show. They often have the wrong amplitude beyond a few days out. It could be a function of the algos each individual model uses. The location and strength of the VP anomalies are usually a more reliable guide. Plus we have had RMM indices not far from the circle have an impact similar to amplitudes of a much higher range. When the MJO becomes the sole driver of the pattern at times, we can even get a well defined 500mb response when the RMM is near or in the circle with the VP anomalies more representative of the pattern.
So if the +AAM response begins to wane by mid to late December, even a little tropical forcing in the warmer phases can go a long way when it becomes more of a pattern driver. Our best bet for mid to late December is that the long range models are underestimating the +AAM response. And that the other tropical forcing like the MJO remains in background. 
Also remember that background tropical forcing in the warmer regions can have some influence on the storm tracks. Even when other features are stronger pattern drivers. We see this at times when a storm takes a cutter track and the cold comes in after the storm with Niña-like background forcing and too dominant of a northern stream.
 

We are starting to see the effects of the MJO forcing and the WWB induced +AAM wearing off on the models in the long range. They are becoming aggressive with developing a -PNA around mid-month and pumping a SE ridge/WAR. The models are also getting stronger with the EWB in 3.4 and developing a pronounced Modoki event.

It looks like the SPV is going to get very strong with nothing to limit it strengthening into mid-December. Luckily still no signs yet of it becoming coupled with the TPV or it would completely rout any source of arctic air and lock it over the pole. It is however, following the typical high solar/+QBO/-ENSO progression so far

 

 

 

 

[Terpeast]

2 hours ago, bluewave said:

You can’t go by the forecast amplitude that those RMM charts show. They often have the wrong amplitude beyond a few days out. It could be a function of the algos each individual model uses. The location and strength of the VP anomalies are usually a more reliable guide. Plus we have had RMM indices not far from the circle have an impact similar to amplitudes of a much higher range. When the MJO becomes the sole driver of the pattern at times, we can even get a well defined 500mb response when the RMM is near or in the circle with the VP anomalies more representative of the pattern.

So if the +AAM response begins to wane by mid to late December, even a little tropical forcing in the warmer phases can go a long way when it becomes more of a pattern driver. Our best bet for mid to late December is that the long range models are underestimating the +AAM response. And that the other tropical forcing like the MJO remains in background. 

Also remember that background tropical forcing in the warmer regions can have some influence on the storm tracks. Even when other features are stronger pattern drivers. We see this at times when a storm takes a cutter track and the cold comes in after the storm with Niña-like background forcing and too dominant of a northern stream.
 

While we can’t take the rmm forecast amplitude literally, I still think rmm forecasts have some utility where we look at multiple models/ens and look at what phases they think the mjo will be in and how quickly or slowly they cycle through. The spread gives a good idea of the uncertainty of the amplitude, which can be really noisy. Even in noisy amplitude predictions, we can get a good idea of where the mjo is going to be, phase wise, in a week or two ahead of time. 

[GaWx]

Latest CFS ensemble AAM forecast: fairly similar to prior forecast with largely a moderate +AAM (El Ninoish). Most notable to me is that it hangs on and is even stronger at very late month although that’s a highly fwiw since these CFS forecasts aren’t the least bit reliable that far out:

Prior forecast (from one week ago):

[snowman19]

10 minutes ago, GaWx said:

Natural gas is up rather notably this morning (+4%) indicating that the two week forecast is most likely at least hanging on to continued cold domination in the E US, if not colder than how it looked before Thanksgiving. 

I don’t think there’s any question that the 1st 2 weeks of December look cold. The ambiguity starts mid-month. The GEFS is going to a -PNA/SE ridge pattern, EPS holding status quo. Shades of the last couple of years when the EPS was really bad with the PAC pattern and it played catch up as we got closer. Last winter in particular, the EPS was pretty bad in that regard. I’m not really sure what they did with the upgrades, but at least on the PAC side, the EURO leaves a lot to be desired 

[bluewave]

55 minutes ago, Terpeast said:

While we can’t take the rmm forecast amplitude literally, I still think rmm forecasts have some utility where we look at multiple models/ens and look at what phases they think the mjo will be in and how quickly or slowly they cycle through. The spread gives a good idea of the uncertainty of the amplitude, which can be really noisy. Even in noisy amplitude predictions, we can get a good idea of where the mjo is going to be, phase wise, in a week or two ahead of time. 

It takes time for the models to catch up with the correct amplitude. So I just look at the longitude along the equator where the strongest convection and VP anomalies are showing up. But I agree that the number of the phase through a week to 10 days is fairly close on both the RMM and VP anomalies. It’s after about 10 days that the models can really loose the RMM signal correct phase in the noise and the VP anomalies are a bit more reliable for both phase and magnitude. After 15 days models often  loose or dampen the convection too much so that even the VP anomalies struggle. But I know enough about model MJO biases 2-3 weeks out that I can correct the models manually and get a general idea where the MJO is going when it’s active enough. 

[michsnowfreak]

The Lakes are cranking. No more kicking the cold can...Winter has arrived. Looking for huge totals in parts of upstate NY and upper MI. Woke up to a fresh blanket of snow here as well with squalls looking to hit later today and tonight.

 

[bluewave]

2 hours ago, snowman19 said:

We are starting to see the effects of the MJO forcing and the WWB induced +AAM wearing off on the models in the long range. They are becoming aggressive with developing a -PNA around mid-month and pumping a SE ridge/WAR. The models are also getting stronger with the EWB in 3.4 and developing a pronounced Modoki event.

It looks like the SPV is going to get very strong with nothing to limit it strengthening into mid-December. Luckily still no signs yet of it becoming coupled with the TPV or it would completely rout any source of arctic air and lock it over the pole. It is however, following the typical high solar/+QBO/-ENSO progression so far

The magnitude and duration of the more +AAM influence will be key. If the +AAM signal can linger into mid to late December, then we’ll have a colder than average December in our area. But should the +AAM influence wane by mid month, then there will be enough Maritime Continent forcing influence so that the early month cold departures are largely erased. 

[snowman19]

9 minutes ago, bluewave said:

The magnitude and duration of the more +AAM influence will be key. If the +AAM signal can linger into mid to late December, then we’ll have a colder than average December in our area. But should the +AAM influence wane by mid month, then there will be enough Maritime Continent forcing influence so that the early month cold departures are largely erased. 

Agree about the MJO Maritime Continent forcing. My guess is that the models have to adjust to the new EWB/+SOI/ENSO 3.4 cooling regime before you see an across the board reflection in the AAM. Just like the models adjusted to the unexpected WWB/+AAM spike/ENSO warming we saw a couple of weeks ago 

[leo2000]

Source from Bamwx

Big colder trends on the mid-day GEFS - a step towards our forecast of staying COLDER through Mid-December vs. warmer weekly data.

 

 

[Stormchaserchuck1]

^Would be some snow threats too if that pattern holds, with the NAO positive (+NAO's are wetter).  This is the pattern we were talking about in this thread, this Summer.. +NAO and -EPO have been correlating lately for the last 11 years. 

[MJO812]

[MJO812]

Looking like a relaxtion period mid December.  Hopefully it doesn't last too long.

 

 

 

Have to see where the MJO ends up

[bluewave]

33 minutes ago, MJO812 said:

Looking like a relaxtion period mid December.  Hopefully it doesn't last too long.

 

 

 

Have to see where the MJO ends up

While the amplitude of this latest RMM extension may vary, the slow motion through the Maritime Continent moderating phases aligns well with the VP anomalies. So we get the ridge returning to the East in Mid December. With a little luck the wave can progress into phase 8 in January and not reload again in 5-7.

[snowman19]

@Bluewave The entire ENSO gyre is switching into a mode much more favorable for region 3.4 cooling, +SOI and enhanced trades finally. This should wipe out the +AAM/Nino like effects. Paul is expecting this to continue throughout December and possibly into early January. It’s also going to constructively interfere with the MJO Maritime Continent forcing and the -IOD. The question is do we see enough cooling to get a trimonthly weak Niña ONI? Paul thinks the distinction between weak La Niña and cold-neutral really isn’t going to matter in this case:
 

 

 

 

 

 

 

 

 

[bluewave]

2 minutes ago, snowman19 said:

@Bluewave The entire ENSO gyre is switching into a mode much more favorable for region 3.4 cooling and enhanced trades finally. This should wipe out the +AAM/Nino like effects. Paul is expecting this to continue throughout December and possibly into early January. It’s also going to constructively interfere with the MJO Maritime Continent forcing and the -IOD. The question is do we see enough cooling to get a trimonthly weak Niña ONI? Paul thinks the distinction between weak La Niña and cold-neutral really isn’t going to matter in this case:
 

 

 

 

 

 

 

 

 

You can see the more Niña-like influence beginning to show up in the 500mb pattern as we approach mid-December with higher heights in the East relative to previous runs.

New run

 

Old run

 

[qg_omega]

3 minutes ago, bluewave said:

You can see the more Niña-like influence beginning to show up in the 500mb pattern as we approach mid-December with higher heights in the East relative to previous runs.

New run

 

Old run

 

there goes the winter window

[snowman19]

2 minutes ago, bluewave said:

You can see the more Niña-like influence beginning to show up in the 500mb pattern as we approach mid-December with higher heights in the East relative to previous runs.

New run

 

Old run

 

Agree. The consistent +SOI run is indicative of ENSO-atmospheric coupling. And if people are correct that there’s tropospheric coupling with the upcoming record strong SPV, that’s a really bad sign with the PAC changing the way it is. That’s going to re-enforce +AO/+NAO and leave no way to possibly blunt the PAC onslaught 

[bluewave]

9 minutes ago, snowman19 said:

Agree. The consistent +SOI run is indicative of ENSO-atmospheric coupling. And if people are correct that there’s tropospheric coupling with the upcoming record strong SPV, that’s a really bad sign with the PAC changing the way it is. That’s going to re-enforce +AO/+NAO and leave no way to possibly blunt the PAC onslaught 

You can see overlapping influences. The lingering +AAM still has a +PNA ridge near West Coast. But the higher 500mb heights in East than previous runs is the MJO 5-6, +SOI, more Niña-like influence. If later model runs develop more of a -PNA  then it will signify that the +AAM influence has decreased even more.  

[brooklynwx99]

considering how god awful extended guidance has been so far, I do expect to relaxation around the 15th, but I wouldn’t lock it in. AK ridging lingering wouldn’t even make this a particularly warm pattern

also, if the Pacific jet is stronger than modeled as it usually is, wouldn’t it lead to the Aleutian trough showing up pushing farther east?

[brooklynwx99]

also, lmao

this is what happens when you rely on the MJO too much

[GaWx]

2 minutes ago, brooklynwx99 said:

also, lmao

this is what happens when you rely on the MJO too much

 Here was the Nov 15th run of the Euro Weeklies for 12/2-8:

And the same run for 12/9-15: