Stormchaserchuck1

Hopefully it materializes. Probably not a given though.

https://www.meteo.psu.edu/ewall/ENSHGTAVGNH_6z/ensloopmref.html 0z EPS has the same thing. NAO is positive Thanksgiving until Dec 6. Now we have a good Pacific during that time, remember 13-14 and 14-15 had a favorable Pacific with +NAO and we did fine snow-wise. The Scan ridge is looking good at the end, but it's more reflecting the warming at 50mb and 10mb.

Warming events don't happen in the Summer. You mean in June in the South Pole?

You don't need a 500mb -NAO to have 10mb warming. Actually history is full of examples where the two are at odds. It correlates +40dm -NAO at Day+0, but a +100dm -NAO at ~+30 days (+25-35 days), which is the end of December. Let's see if we get a 2nd -NAO period later in Dec.

Did he? It was on models, now they have some pretty good +NAO troughing near Greenland with ridging underneath of it on the east coast. I think we are still below average temps though during the ridge because of -epo/+pna at the time.

Yeah it looks like it is MJO driven. The good news is the Pacific continues to act more like "Neutral ENSO" than La Nina. CPC PNA has been positive 21 of the last 29 months, and 12 of the last 19 months since the 23-24 El Nino ended. The 23-24 Strong Nino I believe changed something. I've watched it difficult for N. Pacific ridges to establish and sustain all year. ENSO does correlate the highest in Jan-Feb, but this is a pretty good +PNA now on models for the last week of Nov and early Dec... We had 8 straight +AO months earlier this year. We had 7 straight +NAO months until 2 months ago. The Atlantic side is not in a long term -NAO state, and it's decadal fluctuation index, so the consistency is important. That's why a good month of solid -NAO (2nd half of Nov in December) was looking good! Some change! It's kind of the same pattern happening. Maybe the Stratosphere warming will turn the NAO back negative in the 2nd half of December, but that's because of something, not a default state, which I was hoping for. I still think we see -AO tendency this Winter because of low N. Hemisphere 500mb heights in the Summer and Fall.

The Pacific looks good with MJO going through Phase 7 and possibly Phase 8.. models are developing and have trended toward a +PNA pattern. The Atlantic was looking blocky earlier in the month and that was exciting because it was associated with a Stratosphere warming to help sustain the pattern until possibly early January. In the last few days a big +NAO appeared in the medium range, and the 10mb warmings doesn't look as strong, although it's still a Strat warming happening. We will probably get colder later in the month, but it kind of has a bad taste when the fundamentals were looking so good, now it's just a MJO-amped pattern and nothing more. By fundamentals I mean holding a -NAO for more than 10 days.

Not going to ignore the big +NAO that came out of nowhere the last few days. A week ago models had persistent -NAO through Nov and Dec, and I think I actually made a few comments about how rare that has been. Almost all -NAO's have lasted only 10 days then gone away or switched positive. Well there it is again. Since 10-11, we haven't had a -NAO Winter for this reason, and 19/19 Winter months with NAO value >1.12 in that time have all been positive! That's the decadal phase we're in. It was looking hopeful that this year would start off different, but that's changed in the last few days.

Yeah, the 0z Euro looks really good for Stratosphere warming, coming in 3 bursts, and holding strong through December 4. Dec 4th has a +30-35 day normal lag as a secondary event to the troposphere, so we're correlating with -AO conditions to the 1st week of January.

This is the pattern that a lot of us were talking about this Summer and Fall, showing itself in the first few days of December already! @40/70 Benchmark -AO/+NAO It has still shown difficult for an Aleutian ridge to get established and hold persistent.. notice how the Pacific is +PNA there. Could be the MJO passing through 7-8, too. Kind of a "Neutral ENSO" type thing in the N. Pacific, imo. -AO near 90N does correlate with cold around 45N, but it doesn't actually usually go south of 40N, unless the ridge moves over the Davis Strait or northern Canada. We saw this pattern last February. We'll need that +PNA to get going, amping a ridge over the West Coast to get a far SE pushing cold shot, at least in the first part of December.

They are catching onto the time-lagged -NAO from November Stratosphere warming (late Dec -NAO). Still, that Dec 1-7 map is pretty significantly different from a few weeks ago.. the seasonal models don't fluctuate that much.

It's too bad it's not a month later or this would be a decent snowstorm, at least here. It's the rising-out-from-negNAO storm.

Love that deep trough NW of Hawaii. You don't can kick when the players are in position - it would take a whole re-alignment of the N. Pacific 500mb pattern, which is a little bit beyond the average model error. I think the wild card is the MJO and what it does. Seems models are betting on it staying strong. They want to have more of a -PNA pattern if the MJO goes weak, but I'm not seeing it: 21 of the last 29 months have been +PNA [CPC], and since the 23-24 Strong Nino flipped to negative-ENSO, 12 out of 19 months have been +PNA.

I've found that N. Atlantic SSTAs for Wintertime NAO pattern have a real strong correlation the leading May - August. I think later in the Fall and the Winter is more a product of the pattern, but there are pretty high correlation numbers at this time of the year as well. I think the Summer when things stabilize, subsurface temps can be seen in the surface SSTA profile. There is data that allows us to plot a list of 75-analog years to something like following Winter NAO conditions. In May-Aug the correlation goes up to +0.5 (75%)! but in Nov-Dec it's +0.25 (62.5%). Still a pretty strong correlation: You really want to see cold water off the East coast from NC to off of New Foundland. Which I guess we have to some extent. The above map is default positive, so a negative NAO goes to the opposite of those anomalies. The tripole pattern pattern actually holds a future NAO state pretty well. The same tripole pattern works for Jan-Feb to March-Apr NAO, and really throughout the year. Pretty high leading pattern here, given how secondary SSTs are.

CFS is wacky. It also has a huge ENSO bias. Notice that it runs 4 times a day, that run cited above was 12z today, different from 6z. A few weeks ago they had 90% of the country below average on the 12z run, then the 18z run had 95% of the country above average. I've seen 5-6 runs this year where it had the PNW <-30F for December 2025.. Now long range models are showing a +PNA to start Dec and a ridge going up the west coast or just west of it. The CFS had the same thing last year (-30F in the NW for Dec), and last Dec was +PNA.

If the peak is Nov 25-30, history says strong -NAO correlation, based around Dec 30 - Jan 4.

18z GEFS hr384

Long range models around the turn of the month are wanting to develop some kind of 500mb low north of Hawaii, +PNA under the -EPO/-WPO. There really no sign of a RNA pattern. That's why I think the 3-4 week CPC outlook put out today, Euro weeklies, and seasonal monthlies for Dec (CFS, CanSips) are wrong having the cold in the Upper Midwest, and a SE ridge, above average in the SE, US, and average in the Mid Atlantic. MJO could be holding strength going into 7-8-1 around the 1st half of December, and I think it's a below average temperature pattern everywhere east of the Rockies, at least for the 1st half of the month.

Yeah pretty classic -EPO showing up for the last few days of the month Models at that range did just completely lose a sustained -NAO, so let's see if it hold when we get closer... but it does match weak-negative ENSO/strong -QBO analogs for late Nov/early Dec

+PNA pattern trying to build at 384hr on the 18z GEFS. As PSUhoffman posted, we can get snow from this pattern. Let's see if it develops and holds as we get closer

I wonder if the Stratosphere warming forecast is going to stay so strong going into the last week of November, with models tonight taking away the -NAO in the long range. Here's the 1989/2005-analog pattern with weak-negative ENSO and strong -QBO. This is for Nov 28, based on tonights 0z GEFS

Good news and bad news The bad news is, models took away the prolonged/sustained west-based -NAO that it had been showing, the last few runs. The good news is, around the turn of the month they are developing a strong -WPO pattern with +PNA underneath of it -- a Pacific based cold pattern that should put much of the CONUS below average to start off December 0z GEFS mean hr384

Nice post Larry.. Jan Natural Gas is the highest priced contact of the Winter season, implying this is the most -NAO month, but I think the weak-negative ENSO/-QBO might turn us warmer after December, maybe more Pacific-driven warmth. I do see -AO tendency in January this year. Also, Nov 24 - Dec 7 typical lag to -NAO is +35 days, so that is most correlated to -NAO Dec 29 - Jan 12

Kind of limited data. History does say the average PDO cycle is just about as long as we've been in since 1998, but we seem to be at the most extreme part of the cycle now and common sense says that's probably another 10-15 years to neutralize. I know the NOAA has been doing subsurface passes in the PDO area, and there is warmer water down to -200m now more than ever before, which could be 5-10 years to change phases cleanly. There are sometimes 2-3 year phases blips in a long term opposite phase though.

Yeah but after 5/6 La Nina years, we have a tendency to flip for the next 3-5 years, and that happens immediately after 4/6 consecutive ENSO events or greater.. I'd give it 2/3 chances for El Nino next year, even if it's weak..