GaWx

Regardless, there’s been and looks to continue to be plenty of winter (cold and/or wintry precip) in most of the E US through the first half of Dec at least. Despite the weak -PNA, there’s a very rare combo of a very long moderate amp phase 8 MJO, a -NAO, and a -AO to more than compensate. -NAO: wasn’t seen dominating the 1st 1/2 of Dec as recently as 5 days ago -AO: wasn’t seen dominating the 1st 1/2 of Dec as recently as 5 days ago

Today’s MJO forecasts: 1. EPS is once again very steady and has a 15+ day long phase 8, the longest winter phase 8 in 50 years: one couldn’t place it in a better position in Dec for the entire 2 weeks for E US cold lovers: GEFS has been more jumpy than the EPS from day to day: today it still has a 9 day long phase 8, which itself would still be the longest in winter since Feb of 2019’s 9 days, before backtracking to phase 7:

Hey Don, If a -PNA verifies for Dec, which is becoming increasingly likely as you’re implying, the chances for a +PNA in Jan are increased based on the last 11 -ENSO -PNA Decs all proceeding to a +PNA Jan. This includes Jans like 1985, 2011, 2014, and 2022. There was even some tendency for the strongest +PNA of these Januaries to follow the strongest -PNA of these Decembers. Dec: Jan: Feb: @EastonSN+PNA in Dec of 2008 was -1.41 and was +0.61 in the much colder Jan.

Holy Euro Barney!

It would seem quite possible considering the indices: - rising -NAO - rising -AO - weak MJO phase 8 (near or inside circle) - quick +PNA spike

The Nov 30 mb QBO came out about as expected at -25.35, slightly lower than Oct’s -24.65: https://psl.noaa.gov/data/correlation/qbo.data

I just realized we don’t yet have a December 2025 thread. Please post about your own obs as well as about other current or recent wx from any location. Please pin this and unpin Nov @buckeyefan1. Thank you.

Don’t forget 2022 and 2017, which were NN in the SE.

These, especially the first map, are consistent with typical phase 8 MJO in the E US:

In the SE, Dec of 2019 in F was +2 to +5 vs Dec of 2023’s 0 to +3. So, 2019 was 2 warmer.

This is downright ugly for the SE 12/15-1/12 (ECMWF site, itself, is warmer than WxBell’s interpretation), but I’m hopeful it’s overdoing the SER like it has been recently. Plus, this period is still a near eternity away forecasting credibilitywise, especially holidays onward.

The Euro Weeklies have a potent mean SER/-PNA Dec 15th-Jan 11th. Though the Weeklies have over forecasted the SER recently, it’s getting increasingly likely that Dec will average a -PNA. Since 1983-4, there have been 11 -ENSO winters with a -PNA. All 11 had a +PNA in the subsequent Jan. Based on this, the odds of a +PNA for Jan averaged out are increasing. If that were to verify, the chances would be high that the Euro’s potent -PNA Jan 1-11 will be wrong. We’ll see. 12/15-21: 12/22-28: 12/29-1/4: 1/5-11:

Today’s MJO forecasts finally came out: GEFS: Phase 8 12/2-16 (15 days+) EPS: Phase 8 12/3-16 (14 days+) Should either of these progs verify, it would be the longest winter phase 8 in 50 years!

The updated PDO (for 11/30) rose some more to -0.46 (from -0.51 on the prior day):

This from BAMwx’s Michael Clark was released ~30 minutes ago. I’ve yet to watch it. Hopefully it’s reasonable and not swinging for the fences too much: @donsutherland1

GEFS AO forecasts: Just 4 days ago (11/28 run), it was forecasting the AO to be at +0.7 on Dec 7th (only 9 days out): Today’s run (12/2) has the Dec 7th AO way down to -2.3 or 3.0 lower than the run from a mere 4 days ago: Thus, even the ensemble means when looking out just 8-10 days have recently been missing high latitude blocking. So, for the time being, I’m taking the 11-14 day progs with more of a grain than usual. Edit: Today’s MJO runs are running very late at my sources. I still don’t see them.

Just to clarify, this is the WCS PDO, which is often ~~0.75-1.00 <NOAA PDO. So, this implies that the equivalent Nov 29th daily NOAA’s is ~-1.25 to -1.50. I estimate Nov’s NOAA PDO will come out to ~-1.75 to -1.90 vs Oct’s -2.40 and July’s -4.16, which would show the strong rise.

On Nov 29th, the WCS daily PDO rose from ~-0.81 to -0.52, the fastest daily rise since Sept. 2nd:

Here’s the 12Z EPS’ 360 showing very cold in W Canada, which wasn’t on the 0Z, poised to plunge into the N Plains soon afterward: (taking with a grain for now since its out at 360 but MJO would support cold returning to the Midwest/NE): This caused NG to rise 3% in just 40 minutes, bringing it to its highest since way back in Nov. of 2022!

The AK vortex is there for only 5 days (days 5-10) after which it’s pushed well inland. By day 15, it’s way different per 12Z ens: 12Z GEFS: 12Z EPS:

The NY Post is a tabloid that’s not surprisingly making things sound over the top (and there’s even a typo for goodness sakes): -the NE is to be blasted with the “most extreme cold on Earth” per “shocking new forecasts”.

I don’t know as the models are already very cold with MB normal in the NE, Mid-Atlantic, and Midwest for the 10 days that start with the start of phase 8 on 12/3: 6Z GEFS: 0Z EPS:

Having a quick restrengthening of the SPV didn’t stop the rest of the winter (through early March) from being cold in these two cases and that was the case even with +NAO dominating! 2002-3: Jan 17th SSWE followed by avg just 2 weeks later 1993-4: Jan 1st very weak SPV followed by just below avg just 2 weeks later and mainly above avg rest of winter:

Change of GEFS AO/NAO forecasts in just 3 days shows how clueless they can be: is it in this case related to the 11/28/25 major SSW?? I’m asking because similar cluelessness was still the case on the day of the 2/16/23 SSWE: 1. AO Just 3 days ago (day of SSWE): ~+1 for 2nd wk of Dec Today: ~-1 for 2nd wk of Dec! 2. NAO Just 3 days ago (day of SSWE): slight +NAO 2nd wk of Dec Today: slight -NAO 2nd wk of Dec @donsutherland1

Today’s 2 week MJO forecasts: GEFS/EPS agree on longest winter phase 8 in 50 years that starts on Wednesday, even longer than the very long/very cold ones of Feb of 2010, Dec of 1989, and Jan of 1985: