2024-2025 La Nina

[brooklynwx99]

also seeing favorable trends out west for the Christmas timeframe

could be a seasonal trend to underdo western ridging

[Stormchaserchuck1]

January correlation following +PNA December's

[Terpeast]

5 minutes ago, Stormchaserchuck1 said:

January correlation following +PNA December's

Looks like +PNA decembers tend to roll into January and maintain a ridge out west? 

[Terpeast]

45 minutes ago, brooklynwx99 said:

also seeing favorable trends out west for the Christmas timeframe

could be a seasonal trend to underdo western ridging

Very nice trend. I like how the ridge axis is shifting west as it comes forward in time. 

[Stormchaserchuck1]

44 minutes ago, Terpeast said:

Looks like +PNA decembers tend to roll into January and maintain a ridge out west? 

They have a +NAO tendency, and yeah keep that ridge out west. I would be surprised if the Winter is that big of a bust in the NW though, as CPC had 2nd tier below average, and a lot of the seasonal models were cold there too. It kind of reminds me of the hurricane season when the NHC went with 18-25 storms, and that was looking like a huge bust until it caught up at the end and hit at 18. 

It's an individual roll forward, as it doesn't really consider ENSO subsurface, PDO, and really the decadal trend of -PNA right now. I think the big takeaway is that there is average to slightly above average temps in the Midwest and East, when a +PNA straight up in January is a very cold pattern in the East (-0.5 correlation, or 75%). So if we hold +PNA through January, it's cold, but December by itself doesn't necessarily show that. 

[George001]

1 hour ago, brooklynwx99 said:

also seeing favorable trends out west for the Christmas timeframe

could be a seasonal trend to underdo western ridging

The interesting thing is this really isn’t a La Niña pattern with the Aleutian troughing, that’s a Nino pattern if anything. I do think we could see some additional Nina features show up deeper in the winter (I expect this) but even if a Nina does develop it will be weak so not a major pattern driver like it was in 07-08, 10-11, 20-21 etc. 

[George001]

Seasonal guidance is still transitioning to more of a Nina temp distribution Jan-Mar with a cold north/warm south look. I’m not entirely sure it plays out like that, but it’s really not a bad look for the east. I really wouldn’t hate to see a weak Nina develop. It’s a good thing ENSO is weak because there coldest anomalies are over regions 3.4 and 4, not 3 and 1.2. If we did get a mod-strong Nina we would likely have been looking at a 11-12 or 22-23 redux. 

[mitchnick]

Been a while since I've seen this ensemble prediction in a December with Enso 3.4 hovering at -.5C.

[George001]

I’m not even sure it matters too much whether or not an official Nina develops. We could easily see a Nina CONUS wide temp profile even with a -0.3 or 0.4 ONI for Jan-Mar. The question is where will the gradient set up?

[George001]

PDO has risen from below 3 in October to -1.63 now. No, it’s not going to turn positive this winter. But if this warming trend in the PDO region continues it may only be weakly negative by Feb.

[Daniel Boone]

1 hour ago, George001 said:

Seasonal guidance is still transitioning to more of a Nina temp distribution Jan-Mar with a cold north/warm south look. I’m not entirely sure it plays out like that, but it’s really not a bad look for the east. I really wouldn’t hate to see a weak Nina develop. It’s a good thing ENSO is weak because there coldest anomalies are over regions 3.4 and 4, not 3 and 1.2. If we did get a mod-strong Nina we would likely have been looking at a 11-12 or 22-23 redux. 

Enso is weighted heaviest in the Seasonals. That's one reason they miss so much at range sometimes. This fall/ early Winter a good example. La nina was predicted to be well established by December a couple months ago and Seasonals were showing accordingly. Other Drivers sometimes overpower and alter a typical Enso pattern as we know too. Ie, 2010-11. Models were straight Nina Textbook for that Winter as I recall. 

   So, could be what's going on with them here.

[bluewave]

Very fast Pacific flow continues. Warm up next week followed by a cool down before Christmas. Then another warm up near to after Christmas. Looks like the TPV may be trying to consolidate at that time with a +EPO +AO.

[Terpeast]

3 minutes ago, bluewave said:

Very fast Pacific flow continues. Warm up next week followed by a cool down before Christmas. Then another warm up near to after Christmas. Looks like the TPV may be trying to consolidate at that time with a +EPO +AO.

I see signs of the aleutian low retrograding at the end of the ensemble runs, meaning better cold source and potentially -epo. Too soon to make a call one way or another. 

[bluewave]

11 minutes ago, Terpeast said:

I see signs of the aleutian low retrograding at the end of the ensemble runs, meaning better cold source and potentially -epo. Too soon to make a call one way or another. 

The Aleutian Low keeps verifying further east than the long range forecasts have been indicating with the faster Pacific Jet.

[Terpeast]

51 minutes ago, bluewave said:

The Aleutian Low keeps verifying further east than the long range forecasts have been indicating with the faster Pacific Jet.

This Aleutian low had just formed only recently, so there’s not much of a track record for it verifying further east this season. What has been happening for a while is that the epo has been verifying lower than forecast, cold has been trending colder in shorter lead times, and the torch keeps getting delayed. 

But we can agree that December has been a volatile month and no one pattern has been locking into place. It may be correct to attribute that to the fast pacific jet.

[roardog]

49 minutes ago, bluewave said:

The Aleutian Low keeps verifying further east than the long range forecasts have been indicating with the faster Pacific Jet.

It seems like the models have been trying to lower the heights in Alaska and western Canada after day 10 for awhile now but as we get closer in time more ridging keeps showing up. The forecasted cold in the east next week that wasn’t showing up even a couple of days ago is a good example of this.

[bluewave]

35 minutes ago, roardog said:

It seems like the models have been trying to lower the heights in Alaska and western Canada after day 10 for awhile now but as we get closer in time more ridging keeps showing up. The forecasted cold in the east next week that wasn’t showing up even a couple of days ago is a good example of this.

If you look at the monthly forecasts issued back on December 1st, then you will see the Aleutian Low pressing closer to Alaska with a stronger Pacific Jet than forecast. This will be evident when the next 2 weeks get averaged in with the first half of December. The models originally missed the big warm up this week with 60s. Plus they also were too cold with the warm up forecast for next week. The reason they missed the cool down before Christmas is that a piece of Pacific energy was able to make it through near Alaska and drop south. But after that the Aleutian low will move back east again for another warm up near or after Christmas. So the much faster Pacific Jet has been the one common denominator. 

[GaWx]

1 hour ago, bluewave said:

If you look at the monthly forecasts issued back on December 1st, then you will see the Aleutian Low pressing closer to Alaska with a stronger Pacific Jet than forecast. This will be evident when the next 2 weeks get averaged in with the first half of December. The models originally missed the big warm up this week with 60s. Plus they also were too cold with the warm up forecast for next week. The reason they missed the cool down before Christmas is that a piece of Pacific energy was able to make it through near Alaska and drop south. But after that the Aleutian low will move back east again for another warm up near or after Christmas. So the much faster Pacific Jet has been the one common denominator. 

 It appears to me that the models initially missed in the E US the intensity of both the 11/30-early Dec and upcoming pre-Christmas cold periods. Also, the current and last couple of days of cold based on memory appear to have been initially well forecasted pretty far back before being warmed a bit too much prior to returning to accuracy. So, overall the models have been under doing cold periods. But they’ve also not been warm enough during the mild periods in between including the upcoming one 12/16-8.

[GaWx]

2 hours ago, Terpeast said:

I see signs of the aleutian low retrograding at the end of the ensemble runs, meaning better cold source and potentially -epo. Too soon to make a call one way or another. 

 Here in the SE I always prefer the El Ninoish mean Aleutian low dominating as that’s typically part of (or at least associated with) a +PNA and minimizes a SE ridge.

[bluewave]

2 hours ago, Terpeast said:

But we can agree that December has been a volatile month and no one pattern has been locking into place. It may be correct to attribute that to the fast pacific jet.

Yeah, the Niña-like forcing west of the Dateline is probably enhancing the Pacific Jet along with the strong SST gradient east of Japan. But the Nino-like forcing over the EPAC with the +AAM keeps building the +PNA ridge. So we get the ridge building out west only to pushed further east from time to time by the faster Pacific flow.

Unusual split Pacific forcing pattern with both La Niña and El Niño elements at the same time

 

 

 

[GaWx]

OISST is very close to its lowest anomaly of the year, which was set ~Sept 20th. This means the equivalent RONI daily is likely now back to low end moderate:

[jbenedet]

Significant El Niño conditions this time last year; low end Nina conditions this year…But….

Snow cover in the northeast US and southeast Canada is basically same as this day last year. Percentage wise and area coverage. Strikingly similar.

 

 

[michsnowfreak]

20 minutes ago, jbenedet said:

Significant El Niño conditions this time last year; low end Nina conditions this year…But….

Snow cover in the northeast US and southeast Canada is basically same as this day last year. Percentage wise and area coverage. Strikingly similar.

 

 

They are somewhat similar but I wouldn't say basically the same. Snow is much deeper in Canada and the temps couldn't be more different the last 2 decembers. The lack of snow in many locations is due to how dry it has been the last several weeks.

 

[GaWx]

 Based on the GEFS chart’s PNA mtd as well as the 0Z GEFS 14 day PNA prog, we have a chance to break the all-time record (since 1950) +PNA for a non-Nino Dec. I estimate based on dailies that the (tabular equivalent) MTD is ~~+1.8. The prog avg (tabular equiv) for the next 2 weeks is near that meaning the progged MTD through Dec 27th is ~~+1.8. *Keep in mind that the tabular equivalent is ~~twice the dailies.* Also, keep in mind that the 10 day GEFS progs have verified significantly too low since late Nov as they’ve averaged only ~half as high as verifications.

 

 Current highest tabular Dec +PNA for non-Nino:

2020: +1.58

1960: +1.46

1985: +1.39

2005: +1.38

2000: +1.23

 

 Highest tabular Dec +PNA for El Nino:

2006: +1.86

1969: +1.84

1963: +1.77

2002: +1.59

1986: +1.37

0Z GEFS prog through 12/27 and mtd: ~+1.8

Tabular monthly PNA 1950+:

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

[GaWx]

2 hours ago, GaWx said:

 Based on the GEFS chart’s PNA mtd as well as the 0Z GEFS 14 day PNA prog, we have a chance to break the all-time record (since 1950) +PNA for a non-Nino Dec. I estimate based on dailies that the (tabular equivalent) MTD is ~~+1.8. The prog avg (tabular equiv) for the next 2 weeks is near that meaning the progged MTD through Dec 27th is ~~+1.8. *Keep in mind that the tabular equivalent is ~~twice the dailies.* Also, keep in mind that the 10 day GEFS progs have verified significantly too low since late Nov as they’ve averaged only ~half as high as verifications.

 

 Current highest tabular Dec +PNA for non-Nino:

2020: +1.58

1960: +1.46

1985: +1.39

2005: +1.38

 

 Highest tabular Dec +PNA for El Nino:

2006: +1.86

1969: +1.84

1963: +1.77

2002: +1.59

0Z GEFS prog through 12/27 and mtd: ~+1.8

Tabular monthly PNA 1950+:

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

Followup:

The 5 highest tabular Dec +PNAs for non-Nino on record (2024 progged to have good chance to be new highest):

2020: +1.58

1960: +1.46

1985: +1.39

2005: +1.38

2000: +1.23

 

 Where were the subsequent Jan tabular PNAs for these non-Nino high +PNA Dec?

2021 +0.19

1961 +1.41 (4th highest on record for non-Nino)

1986 +0.97 (tied for 7th highest on record for non-Nino)

2006 +0.43

2001: +1.51 (3rd highest on record for non-Nino)

Avg Jan for these 5: +0.90

 So, as I think @Stormchaserchuck1was suggesting (actually he was suggesting for all ENSO), +PNA in Dec tends to carryover into Jan for non-Nino. Three of the 5 did strongly and one weakly. The other (2020-1) went to neutral. So, none even went to a weak -PNA.

@Terpeast

[snowman19]

3 hours ago, GaWx said:

OISST is very close to its lowest anomaly of the year, which was set ~Sept 20th. This means the equivalent RONI daily is likely now back to low end moderate:

Region 4 is the coldest it’s been this entire event. And agree about the RONI. There is no denying that we are in a “late bloomer” La Niña 

[snowman19]

[snowman19]

If you look at the monthly forecasts issued back on December 1st, then you will see the Aleutian Low pressing closer to Alaska with a stronger Pacific Jet than forecast. This will be evident when the next 2 weeks get averaged in with the first half of December. The models originally missed the big warm up this week with 60s. Plus they also were too cold with the warm up forecast for next week. The reason they missed the cool down before Christmas is that a piece of Pacific energy was able to make it through near Alaska and drop south. But after that the Aleutian low will move back east again for another warm up near or after Christmas. So the much faster Pacific Jet has been the one common denominator. 

You can see that in today’s EPS, GEPS and GEFS runs for late month

[Stormchaserchuck1]

59 minutes ago, GaWx said:

So, as I think @Stormchaserchuck1was suggesting (actually he was suggesting for all ENSO), +PNA in Dec tends to carryover into Jan for non-Nino. Three of the 5 did strongly and one weakly. The other (2020-1) went to neutral. So, none even went to a weak -PNA.

Good work. This is what the Dec +PNA rolls forward to

-30dm Gulf of Alaska Low. Long range models are already picking up on this pattern, where the cold anomaly goes into Alaska, for the end of December. I have often seen when there is a signal ++time, it usually happens before that.  Your examples look like 4/5 they hold, but I would be surprised given the state of other things. I did roll forward record-breaking heat in Phoenix during the Summer, and it gave me a +PNA signal for the following Dec-Jan. 

[mitchnick]

20 minutes ago, snowman19 said:

 

You're re-posting Cohen when he posts a 384 hr Gfs operational map because it supports your warmanista agenda? Oye