GaWx

IF these were to be close to reality, they’d open the door for frigid air to plunge into the US ~12/18-21: MJO phase 8 would be supportive in Dec 12Z EPS: frigid MT/W ND N into SW Canada 12Z EPS: cross polar flow 12Z GEFS: frigid N MT/N Plains/MN northwestward into SW Canada: 12Z GEFS: cross polar flow

The 12Z EPS is hinting at a 3rd NC snow threat on 12/12 with measurable snow from 7 of the 50 members, mainly from lows that move just offshore:

The 12Z Euro has an off the coast low on 12/8 but it’s significantly too warm for snow per 850s/there’s no cold air connection at the surface and it’s actually dry over much of NC outside of far SE part of the state (it would need to get stronger for NC snow per this):

It’s also a matter of perspective. To me that’s a lot of snow in your pic. This area has had that much snow or sleet in the entire winter only 3 times in the last 45 years (1/2025, 1/2018, and 12/1989) and could easily not see that much again for decades.

I’ve never seen any MJO history prior to the BoM’s 6/1/1974.

Natural gas is now near $5, which is the highest in nearly 4 years. NG generally is highest in winter when the E US, especially NE and Midwest, is forecasted to be colder than normal.

For the twelve 6”+ RDU storms since MJO records started, here are the MJO phases with the largest # of these storms:-3: 3.5 28.2” -8: 2.5 16.8” -5: 2 13.2” -1: 1.5 23.7”-7: 1 10.8”-4: 1 5.9”-2: 0.5 9.0”-6: 0 0.0”MJO amplitude:Weak: 63.9” (on or inside circle)Mod 37.8” (1-2 amp)Strong 5.9” (2+ amp)-The MJO is progged to be weak phase 8 Dec 8-9th-All of the 6”+ RDU snows during phases 8, 1, and 2 were when the MJO was inside the circle.-Phase 3 leading may seem counterintuitive but it’s not when considering that 3 of the 3.5 phase 3 storms were during Feb or Mar, when phase 3 is one of the coldest phases:

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: