2024-2025 La Nina

[bluewave]

8 hours ago, 40/70 Benchmark said:

 

Great example of why the only bias these guys have is a "correct" bias...call 'em as they see 'em. The warmth bias crap is really frustration over the past several winters being projected onto them. Ball busting is one thing, but the I suspect some are serious with that crap.

My guess is that the Aleutian Low showing up in all the guidance is a response to the forcing developing near 120W to 150W next few days which is classic El Niño. So we will have dual EPAC and WPAC forcing. The WPAC forcing is probably enhancing the Pacific Jet leading to such a dominant northern stream and weaker STJ. 

 

[LakePaste25]

The Christmas pattern change idea floating around social media is likely rushed (when hasn’t it?). Most of us enjoy cold weather during the Christmas holiday, so the usual wishcasting ensues. We are likely dealing with phase 6 before the pattern potentially becomes more favorable after the New Year. 

[40/70 Benchmark]

13 minutes ago, LakePaste25 said:

The Christmas pattern change idea floating around social media is likely rushed (when hasn’t it?). Most of us enjoy cold weather during the Christmas holiday, so the usual wishcasting ensues. We are likely dealing with phase 6 before the pattern potentially becomes more favorable after the New Year. 

Absolutely. Great post.

[bluewave]

The Nino-like influence is why the EPS is going +6C to +10C in Canada around Christmas which is usually much colder during La Ninas.

[40/70 Benchmark]

1 hour ago, bluewave said:

The Nino-like influence is why the EPS is going +6C to +10C in Canada around Christmas which is usually much colder during La Ninas.

Little taste of last December.

[bluewave]

15 minutes ago, 40/70 Benchmark said:

Little taste of last December.

Yeah, it looks like we are currently on the more Nino-like side of the long range Euro 3.4 plumes.

 

[leo2000]

4 hours ago, LakePaste25 said:

The Christmas pattern change idea floating around social media is likely rushed (when hasn’t it?). Most of us enjoy cold weather during the Christmas holiday, so the usual wishcasting ensues. We are likely dealing with phase 6 before the pattern potentially becomes more favorable after the New Year. 

I don't know about that a lot of model flip flopping going on from ugly to good then back to ugly. The days before Christmas are up in the air on what is really going to happen. 

[snowman19]

@bluewave Still confident in an MJO 8-1-2 fail coming up. The cooler/cooling waters in those phases and the EWBs from the CP/Modoki Niña are going to shear it apart as it propagates east. Plus, the very strong SPV and tropospheric coupling will only potentiate the +NAO

See:
 

[roardog]

17 minutes ago, snowman19 said:

@bluewave Still confident in an MJO 8-1-2 fail coming up. The cooler/cooling waters in those phases and the EWBs from the CP/Modoki Niña are going to shear it apart as it propagates east. Plus, the very strong SPV and tropospheric coupling will only potentiate the +NAO

See:
 

None of this means anything if the pattern is going to look like a Nino. Mild weather is coming but it’s not really because of a Nina look. It’s more strong Nino looking than anything. 

[snowman19]

13 minutes ago, roardog said:

None of this means anything if the pattern is going to look like a Nino. Mild weather is coming but it’s not really because of a Nina look. It’s more strong Nino looking than anything. 

Part of it is absolutely ENSO. If you read through the above tweet, only the NPAC is resembling a Nino, the equatorial PAC is full blown La Nina and it’s going to work to block the MJO from propogating east into 8-1-2 due to the CP Nina standing wave/subsidence/EWB shear and cooler SSTA. So it gets back to @bluewave point of competing influences in the pattern

[GaWx]

 Cold ENSO winters with cold dominating only the first half of Dec. in NE and SE and thus weren’t cold dominated in 2nd half of Dec: how did Jan and Feb turn out in the E US? These are 9 of them since 1874-5:

-2007-8: cold didn’t return in Jan or Feb

-2005-6: cold didn’t return to SE but did to NE in 2nd half of Feb

-1954-5: cold 2nd half of Jan and 1st half of Feb

-1949-50: cold 2nd half of Feb

-1934-5: cold 2nd half of Jan and 1st half of Feb

-1915-6: cold Feb NE and cold 2nd half of Feb SE

-1898-9: historic cold 1st half of Feb 

-1893-4: cold 2nd half of Feb

-1875-6: cold NE 2nd half of Feb; no more cold SE

———

Summary for these 9 cold ENSO winters with cold 1st half Dec and non-cold 2nd half Dec:

-cold returned to NE within Jan and/or Feb in 8 of these 9 with only 2007-8 having no more cold

-cold returned to SE within Jan/Feb 6 of these 9

-most frequent return of cold was (surprisingly to me) in Feb rather than in Jan with 1st half of Feb cold 4 of 9 NE and 3 of 9 SE

-2nd half of Feb cold: 5 of 9 NE and 3 of 9 SE

-2nd half of Jan cold: only 2 of 9 (1954-5 and 1934-5)

-1st half of Jan cold: 0 of 9!

———————————

 So, the above stats tell me that cold will very likely return in NE and pretty likely also in SE but that it would be highly unlikely in early Jan and most likely in Feb. The cold ENSO winters that were often cold in early Jan were cold in all of Dec rather than just in the 1st half of Dec. This is all assuming the models are right and that the 2nd half of Dec won’t be cold dominated. If that turns out to not be the case then chances of cold in early Jan would rise significantly. 

*When I say cold I mean cold domination for at least 1/2 a month.*

[GaWx]

 Keeping in mind the above post about the models having favored a not cold dominated 2nd half of Dec:

 The 12Z Euro *fwiw of course* is cold Dec 19-24. Since this is a cold outlier and that portion is out 9-14 days (largely fantasyland for an operational), it remains a low probability solution imho. But it does show that the fate of the 2nd half of Dec overall is still too far out to yet be set in stone.

[roardog]

I know we talk about RONI and how warm the oceans are and everything but it wasn’t that long ago that 3.4 was actually at a warm neutral level and the SOI was barely positive. We seem to finally be getting some strengthening of the cold waters in that region along with the recent big jump in the SOI. I kind of wonder if the atmosphere is still responding to the warm enso waters we just had. It wouldn’t surprise me if we start to see a more Nina like pattern as we head into January in response to what’s happening right now. 

[PhiEaglesfan712]

3 minutes ago, roardog said:

I know we talk about RONI and how warm the oceans are and everything but it wasn’t that long ago that 3.4 was actually at a warm neutral level and the SOI was barely positive. We seem to finally be getting some strengthening of the cold waters in that region along with the recent big jump in the SOI. I kind of wonder if the atmosphere is still responding to the warm enso waters we just had. It wouldn’t surprise me if we start to see a more Nina like pattern as we head into January in response to what’s happening right now. 

Yeah, it kind of had a 1992-93 flavor to it. That was a backloaded winter, most notable for the mid-March blizzard. Interestingly enough, that one had a cool first third of December, and ended with normal temperature departure. Here was the first third of that December:

1992-12-01	53	34	43.5	1.0	21	0	T	0.0	0
1992-12-02	46	39	42.5	0.3	22	0	T	0.0	0
1992-12-03	48	33	40.5	-1.4	24	0	0.00	0.0	0
1992-12-04	42	31	36.5	-5.1	28	0	0.04	0.0	0
1992-12-05	41	33	37.0	-4.3	28	0	0.14	T	0
1992-12-06	38	25	31.5	-9.6	33	0	0.00	0.0	0
1992-12-07	41	34	37.5	-3.3	27	0	0.00	0.0	0
1992-12-08	42	30	36.0	-4.5	29	0	0.00	0.0	0
1992-12-09	37	24	30.5	-9.7	34	0	0.00	0.0	0
1992-12-10	47	25	36.0	-4.0	29	0	0.97	T	0

The rest of the month:

1992-12-11	52	43	47.5	7.8	17	0	2.25	0.0	0
1992-12-12	44	36	40.0	0.5	25	0	0.17	0.0	0
1992-12-13	46	36	41.0	1.8	24	0	T	0.0	0
1992-12-14	43	30	36.5	-2.5	28	0	0.00	0.0	0
1992-12-15	38	26	32.0	-6.7	33	0	0.00	0.0	0
1992-12-16	47	36	41.5	3.0	23	0	0.03	0.0	0
1992-12-17	60	42	51.0	12.8	14	0	0.47	0.0	0
1992-12-18	47	34	40.5	2.5	24	0	0.00	0.0	0
1992-12-19	50	30	40.0	2.3	25	0	0.00	0.0	0
1992-12-20	49	35	42.0	4.5	23	0	0.18	0.0	0
1992-12-21	40	26	33.0	-4.3	32	0	0.00	0.0	0
1992-12-22	52	33	42.5	5.4	22	0	0.00	0.0	0
1992-12-23	48	33	40.5	3.7	24	0	0.06	0.0	0
1992-12-24	42	22	32.0	-4.6	33	0	T	0.0	0
1992-12-25	37	20	28.5	-7.9	36	0	T	T	0
1992-12-26	37	25	31.0	-5.2	34	0	0.00	0.0	0
1992-12-27	34	19	26.5	-9.5	38	0	0.00	0.0	0
1992-12-28	43	31	37.0	1.2	28	0	0.10	T	0
1992-12-29	50	42	46.0	10.4	19	0	0.05	0.0	0
1992-12-30	51	45	48.0	12.6	17	0	0.15	0.0	0
1992-12-31	63	47	55.0	19.7	10	0	0.00	0.0	0

This is proof that even if December goes snowless, all isn't lost. Heck, January 1993 torched before things turned colder and snowy in February and most of March.

 

[40/70 Benchmark]

1 hour ago, snowman19 said:

@bluewave Still confident in an MJO 8-1-2 fail coming up. The cooler/cooling waters in those phases and the EWBs from the CP/Modoki Niña are going to shear it apart as it propagates east. Plus, the very strong SPV and tropospheric coupling will only potentiate the +NAO

See:
 

The Modoki index really isn't very important with a weak event.

[mitchnick]

37 minutes ago, roardog said:

I know we talk about RONI and how warm the oceans are and everything but it wasn’t that long ago that 3.4 was actually at a warm neutral level and the SOI was barely positive. We seem to finally be getting some strengthening of the cold waters in that region along with the recent big jump in the SOI. I kind of wonder if the atmosphere is still responding to the warm enso waters we just had. It wouldn’t surprise me if we start to see a more Nina like pattern as we head into January in response to what’s happening right now. 

Cfs thinks February will be Nino'ish with NN/BN temps across the northern tier into the MA and way AN precip. It's vacilated over recent weeks on February temps, but very consistent on AN precip.

Before the peanut gallery feels compelled to  curse me, I'm the messenger and not the programmer. Lol

[bluewave]

1 hour ago, snowman19 said:

Part of it is absolutely ENSO. If you read through the above tweet, only the NPAC is resembling a Nino, the equatorial PAC is full blown La Nina and it’s going to work to block the MJO from propogating east into 8-1-2 due to the CP Nina standing wave/subsidence/EWB shear and cooler SSTA. So it gets back to @bluewave point of competing influences in the pattern

Yeah, the bottom line when the Nina and Nino influences overlap is a very fast and mild Pacific flow. 

[PhiEaglesfan712]

MEI just updated, and is back down to -0.7 for ON. This is the 5th straight bimonthly value of -0.5 or below for the MEI, solidifying a weak la nina on there.

[snowman19]

1 hour ago, PhiEaglesfan712 said:

MEI just updated, and is back down to -0.7 for ON. This is the 5th straight bimonthly value of -0.5 or below for the MEI, solidifying a weak la nina on there.

Given the strong background atmospheric/oceanic La Niña state, no surprise at all and the MEI is almost certain to drop lower coming up. It goes back to what @roardog just posted about with the RONI

@bluewave I’m sure you weren’t surprised by the MEI drop

[GaWx]

The new Euro Weeklies:

-still no signal for anything close to major SSW (same for Dec 9 run of extended GEFS)

-Lack of either warm or cold signal for E US persists for Jan 6-19. If last half of Dec ends up not cold, I’ll favor no dominant cold during this period per cold ENSO analogs as dominant cold would likely not return til later.

[PhiEaglesfan712]

9 minutes ago, snowman19 said:

Given the strong background atmospheric/oceanic La Niña state, no surprise at all and the MEI is almost certain to drop lower coming up. It goes back to what @roardog just posted about with the RONI

You never know. The MEI was at -0.7 for JJ/JA, and I was expecting it to drop into moderate or even strong la nina territory for AS/SO. The numbers ended up being -0.6 for AS and -0.5 for SO.

[bluewave]

3 hours ago, snowman19 said:

@bluewave Still confident in an MJO 8-1-2 fail coming up. The cooler/cooling waters in those phases and the EWBs from the CP/Modoki Niña are going to shear it apart as it propagates east. Plus, the very strong SPV and tropospheric coupling will only potentiate the +NAO

See:
 

The split nature of the forcing between the WPAC and EPAC along with what you just said  may slow the convection closer to Phase 7 in early January. I think that’s why all the extended guidance is showing the colder look then. But the interaction with the EPAC forcing may cause some type of interference or shift after that period.

[michsnowfreak]

1 hour ago, GaWx said:

The new Euro Weeklies:

-still no signal for anything close to major SSW (same for Dec 9 run of extended GEFS)

-Lack of either warm or cold signal for E US persists for Jan 6-19. If last half of Dec ends up not cold, I’ll favor no dominant cold during this period per cold ENSO analogs as dominant cold would likely not return til later.

Do you have a link for the weeklies site? I always just use wxbell

[mitchnick]

11 minutes ago, michsnowfreak said:

Do you have a link for the weeklies site? I always just use wxbell

https://charts.ecmwf.int/?facets={"Product type"%3A[]%2C"Parameters"%3A[]%2C"Range"%3A["Extended (42 days)"]%2C"Type"%3A[]}

[GaWx]

25 minutes ago, michsnowfreak said:

Do you have a link for the weeklies site? I always just use wxbell

 

13 minutes ago, mitchnick said:

https://charts.ecmwf.int/?facets={"Product type"%3A[]%2C"Parameters"%3A[]%2C"Range"%3A["Extended (42 days)"]%2C"Type"%3A[]}

Thanks, Mitch. More specifically for N American 2 meter temperatures, here’s the link:

https://charts.ecmwf.int/products/extended-anomaly-2t?base_time=202412100000&projection=opencharts_north_america&valid_time=202412230000

[Terpeast]

The aleutian/GoA low is yet another surprise that many of us didn’t see coming this winter. I didn’t myself, but as I said before, this winter will find a way to throw us a couple of curveballs.

We want to root for the GoA low to retrograde into the aleutians so that we can get a nice PNA to pop, and a negative epo to top it off. Worst case scenario? GoA low stays put, and then La Nina reasserts itself with MJO reloading 4-6 for a SE ridge. 

But I don’t think the GoA low is durable, and the jet should retract some. 

[GaWx]

 The newest BoM biweekly forecast for Nino 3.4 has cooled considerably.

This is the prior one, which had -0.3 for Dec, -0.4 for Jan, -0.1 for Feb, and +0.2 for Mar:

 Here’s the newest one, which has -0.4 for Dec,-0.7 for Jan, -0.5 for Feb, and -0.1 for Mar:

@snowman19

[snowman19]

9 hours ago, GaWx said:

 The newest BoM biweekly forecast for Nino 3.4 has cooled considerably.

This is the prior one, which had -0.3 for Dec, -0.4 for Jan, -0.1 for Feb, and +0.2 for Mar:

 Here’s the newest one, which has -0.4 for Dec,-0.7 for Jan, -0.5 for Feb, and -0.1 for Mar:

@snowman19

This La Niña is very clearly strengthening on all metrics and now the region 3.4 ONI is reflecting it. The drop in the MEI is indicative of a very well coupled (ocean-atmosphere) system as is the RONI and SOI

[PhiEaglesfan712]

Possible backloaded winter: 

[40/70 Benchmark]

12 hours ago, GaWx said:

 The newest BoM biweekly forecast for Nino 3.4 has cooled considerably.

This is the prior one, which had -0.3 for Dec, -0.4 for Jan, -0.1 for Feb, and +0.2 for Mar:

 Here’s the newest one, which has -0.4 for Dec,-0.7 for Jan, -0.5 for Feb, and -0.1 for Mar:

@snowman19

 

4 hours ago, snowman19 said:

This La Niña is very clearly strengthening on all metrics and now the region 3.4 ONI is reflecting it. The drop in the MEI is indicative of a very well coupled (ocean-atmosphere) system as is the RONI and SOI

2008 was the best ENSO analog, as I have been saying...folks bailed on La Nina too quickly.