GaWx

 And here’s even more good trends vs yesterday for cold lovers:

Yesterday’s (11/26) GEFS AO through 12/10: rose to solid +AO of +1:

Today’s (11/27) GEFS AO: neutral/near 0: 

 If the more favorable phase 8 progs today vs yesterday are not enough good news for those who prefer it cold in the E US, I’ve got more:

Yesterday’s (11/26) GEFS NAO through 12/10: headed to moderate +NAO 

Today’s (11/27) GEFS NAO through 12/11: no +NAO as it stops rising at dead neutral (0):

24 minutes ago, Terpeast said:

Yeah, according to hovmollers the models are trending towards weaker forcing at 6/7 after Dec 7. Between now and Dec 7, we have a clean mjo 8 pass. Then weak forcing reappears at 6/7, which is strongest with gefs. But even the gefs begins to propagate that eastward after Dec 7-10. So we may yet get another mjo 8 pass soon afterward.

Yesterday’s (11/26) 2 week EPS (through 12/10): barely made it to phase 8 on Dec 5th-6th before circling back to phase 7 (extended showed it made it back to phase 8 12/13-27+):

Today’s (11/27) 2 week EPS through 12/11: gets to phase 8 on 12/3 and stays through the end of the run (12/11), meaning a 9+ day long phase 8, which would be the longest Dec phase 8 at least since the 10 day long phase 8 of 1989: (tomorrow’s ext EPS will show the total length)

In summary, all GEFS/EPS MJO forecasts are more favorable with regard to phase 8 vs what was available yesterday (2 week and extended). Both of today’s 2 week forecasts (GEFS and EPS) have phase 8 Dec 3-11+.

 Yesterday’s (11/26) 2 week GEFS (through 12/10): didn’t make it to phase 8 (extended showed it made it but not til 12/13):

Today’s (11/27) 2 week GEFS through 12/11: already makes it to phase 8 on 12/3, which is TEN days earlier than yesterday. It remains in phase 8 through the end, meaning it would be a 9+ day phase 8, the longest Dec phase 8 since 1989:

 Yesterday’s (11/26) EPS 2 week MJO forecast through Dec 10th: was then curling back away from 8 after barely getting into it and we were wondering whether it would ever get back to phase 8:

Yesterday’s (11/26) EPS extended, which adds 12/11-27: had a 15+ day phase 8 12/13-27, which would be the 2nd longest phase 8 on record for any month (2nd only to the 18 day long phase 8 of Dec-Jan 1975-6) and the more favorable for cold weak to moderate amp (vs strong) to boot:

Yesterday’s (11/26) GEFS 2 week through 12/10: was then curling back away from 8 and we were wondering whether it would ever make phase 8:

Yesterday’s (11/26) GEFS extended, which adds 12/11-12/27: it turned out that it made phase 8 for an 8 day period (12/13-20), which would be longest phase 8 since Feb of 2019’s 9 day long ph 8 and the longest Dec ph 8 since Dec of 1989’s 10 day long ph 8 along with it being a more favorable for cold weak to moderate amp:

AAM has been verifying much more + than CFS ensemble forecasts have been indicating in the relative short term: if it can’t even get the relative short term right, how credible are these CFS ens. progs?

Today’s (11/27) run has +0.5 to +1.0 late Nov/1st part of Dec:

But look at what earlier runs had for the same period:

11/21 run: -0.25

11/19 run: -1

11/16 run: -1.5

11/11 run: -1 to -1.25

37 minutes ago, donsutherland1 said:

The pattern evolution for the opening 10 days of December still looks very good. With respect to the December 11-25 period, the guidance has shifted. For a time, the GEFS was showing the development of a pronounced AO+ pattern. Now, it has backed off (12z and 18z cycles). As a consequence, the baseline Scenario 1 still seems to be the best one going forward, while recognizing that there is some risk of a break near mid-month. 

The latest ECMWF weekly forecast largely maintains the sensible weather effects from Scenario 1. Given the shifting of the guidance, it makes sense to continue to monitor the teleconnections (and other factors) while reserving judgment for changes until later to avoid making changes based more on model noise than actual developments.

Milwaukee, Chicago, Detroit, and Toronto remain in line for a snowstorm during the November 29-30 period. Significant snow is possible in Milwaukee and Chicago. A moderate snowfall looks reasonable for both Detroit and Toronto. Changes can still occur. WPC is now showing a 70% chance of a moderate winter storm impact in Chicago and surrounding areas for the 24-hour period ending November 30 7 am.

Chicago remains on course to experience its snowiest fall since 2019 (8.3") and possibly even 2018 (12.7"). Milwaukee should see its snowiest fall since 2019 (13.4"). Detroit will likely experience its snowiest fall since 2021 (7.1") and possibly 2019 (9.5"). Toronto could see its snowiest fall since 2020 (23.4 cm/9.2") and perhaps 2002 (27.2 cm/10.7").

Fall 2025 Snowfall Totals (through November 26):
Chicago: 1.7"
Detroit: 2.2"
Milwaukee: 0.6"
Toronto: 12.8 cm (5.0")

 

 Look at how much colder H5 on the Euro Weeklies is compared to yesterday’s: that’s a big change for a 30 day period!

Yesterday’s:

Today’s:

Regarding today’s Euro Weeklies, it’s the most bullish (i.e., colder changes vs prior run) overall in a long time in the NE and SE. I’m not saying they’re cold in the SE,  but they are colder than they were/not as mild or not mild overall. I don’t have time to post details right now, but y’all check it out! Or someone else please post the maps.

Edit: Every one of the 5 weeks is colder and/or less mild in both the NE and SE US vs yesterday’s run including one dramatically colder week. That hasn’t happened in quite awhile.

3 hours ago, John1122 said:

The late month could be, if everything works well, very epic, even beyond this next two weeks with several potential events. The Euro has the MJO in the low amp/c.o.d into late December/Early January. @GaWx has noted that essentially every low amp pass through 8 has coincided with well BN temps, but that high amp passes were not always cold in the east. 

East Asia should become more favorable soon, to allow west coast ridging downstream as well.

Hey John,

 Thanks for bringing up the amp. What you said generally coincides with my thoughts. But I’d like to clarify what I’ve said just to make sure there’s not a misunderstanding. Indeed, various analyses I’ve done over the last 10-11 years or so, which all have involved calculations of actual temperatures in a place or places in the E US, have shown that the average anomalies have tended to be colder with low to moderate amp (1.7 or lower in my latest study, which was 8+ day long phase 8s) vs strong AMO of phase 8. But not “essentially every low amp pass”. It’s more like a majority of low amp have been cold vs pretty balanced for high amp.

 Today’s MJO through 12/10: tune in tomorrow to see what they’ll do 12/11-27:

On 11/25/2025 at 9:18 AM, FPizz said:

Is the ext available to compare the same outputs?  Maybe instead of doing the loop in phase 7, it does it right on the line between 7/8 then goes back into 8.  Yesterdays did the loop in 7

So, now I can give you the answer

Yesterday’s 2 week GEFS (through 12/9/25) was starting to loop in 7 through the end of the 2 week run: was it going to stay in 7 or was it going to go into 8?

 Here’s the much anticipated answer: it ended up doing just a small, quick loop in 7 but then it went a little ways into 8 on 12/11. But that little ways was enough for the moderate amped 8 to last 8 days (12/11-18), which alone would be enough for the longest Dec phase 8 since Dec of 1989’s 10 days and longest, period, since Feb of 2019’s 9 days. However, it then looped back into 7 a little ways 12/19-26 with it stalled at the end. Now my question is whether or not it would have gone back into 8: we’ll never know that far out on this run

4 hours ago, GaWx said:

The colder trend for early Dec is happening on all ensembles including GEFS: these are all for a week from today at 7PM: watch the SER disappear:
 

 

@donsutherland1@bluewave

 The above noted colder GEFS trend for early Dec continued with the 12Z run.

51 minutes ago, TheClimateChanger said:

Interesting. At least at looks to be moving through at a pretty good clip, so might just be a temporary excursion in Phase 8.

That ext Euro phase 8 lasts 11 days, which would be the longest in Dec since 1975. I just hope it actually gets there and stays for awhile rather than curl back to 7 to stay.

24 minutes ago, FPizz said:

Is the ext available to compare the same outputs?  Maybe instead of doing the loop in phase 7, it does it right on the line between 7/8 then goes back into 8.  Yesterdays did the loop in 7

1. No, ext for same run comes out a day later.

——————

2. GEFS 2 days ago:

GEFS yesterday: gets to phase 8 five days earlier than any other GEFS as of then:

GEFS today: curled back very slightly vs yesterday (E US cold lovers wouldn’t want a curl back into phase 7) but very similar to yesterday/look how different it is vs 2 days ago!

Yesterday’s Euro: phase 8 starts 12/14:

Today’s Euro: phase 8 starts 10 days earlier, 12/4, (with a 6+day long phase 8 implied) although I’d want to make sure it isn’t curling back into 7 and staying there:

last time Dec had a 6+ day long phase 8 was way back in 1995 (12/20-5):

Euro Weeklies 2m temps for 11/24-30 and this is before the very recent cooldown for early Dec:

11/17 run:

11/24 run:

The colder trend for early Dec is happening on all ensembles including GEFS: these are all for a week from today at 7PM: watch the SER disappear:
 

@donsutherland1@bluewave

11 minutes ago, donsutherland1 said:

That’s one possible factor that has led me to continue to monitor the period. By the end of November, I think there will be greater clarity.

 I’m wondering if despite the clear warming trend of the Euro Weeklies related to its insistence of a stubborn potent SER along with the current progged switch to a +AO if there’s lower than normal confidence due to a combo of the MJO taking a track that’s often cold (though far from always as we know) and the current very weak SPV, which typically takes 2+ weeks to bring the E US persistent dominating cold.

 I didn’t pick up on this earlier and don’t know if anyone else posted this. Today’s GEFS has phase 8 starting on Dec 8th, which is about 5 days earlier than any other run:

7 hours ago, MJO812 said:

A better pattern still looks on track in December  . MJO going into 8. Delayed but not denied ?

 Your post shows yesterday’s ext EPS predicting an 11 day long phase 8 for 12/14-24 averaging ~2.0 amplitude. The ext GFS is predicting a 12++ day long phase 8 for 12/13-24++ but with a much lower avg amp that with extrapolation would likely be headed to a sub 1.5 amp for the full phase 8 avg.

 Regarding the EPS prog, there hasn’t been an 11+ day phase 8 since back in Feb of 2010 (2/7-17). 

 Regarding the GEFS prog of 12++ days, there hasn’t been a 12+ day long one since way back in Dec ‘75-Jan ‘76 (12/19-1/5)! There have been only two on record of 12+ days: the just mentioned one of 18 days and a 13 day long one 1/19-31/75.

 Also, the 15 long phase 8s (8+ days) have followed long phase 7s (9+ days) only twice out of the 15 cases although the two that did were two of the coldest.

 So, needless to say, I’m taking these very long phase 8 progs with a huge grain for now.

  Of the 15 long phase 8s at Baltimore, the ones averaging an amp of <1.8 (like GEFS has) were significantly colder in the E US on avg than those with an avg amp >1.8 (like EPS has).

 The GEFS-like sub 1.8 amp cases include the very cold outbreaks of Jan of 1985, Jan of 1988, Dec of 1989, and Feb of 2010 with 3+” snows (including historic snow in 2010) for all 4 in Baltimore for example. The other 3 sub 1.8 amp phase 8s had either BN (1) or NN (2) temps at Baltimore. So, even a GEFS-like moderate long phase 8 hasn’t always been cold at Baltimore but rather in most cases and with no mild cases.

 But half of the >1.8 amp long phase 8s were warmer than normal! So, if there’s actually a very long phase 8, I’ll be rooting for one closer to the lower amp of GEFS than the higher amp of EPS due to better prospects for cold per long phase 8 history.

9 hours ago, snowman19 said:

I don’t want to jinx you but it’s looking like a very good call on your part with the SPV, along with the increasingly likely flip to RNA/-PNA in December 

Edit: Also have to give credit to @bluewave with the -PNA December call (looks likely now)

 There has been a +PNA in Jan for all 11 cold ENSO winters that had a -PNA in Dec since 1983-4:

-1983-4: -0.31 to +0.97

-1984-5: -1.60 to +1.63

-1996-7: -1.23 to +0.63

-1998-9: -0.09 to +0.16

-2008-9: -1.41 to +0.61

-2010-11: -1.78 to +1.29

-2012-3: -1.01 to +0.55

-2013-4: -0.86 to +0.97

-2016-7: -0.35 to +0.28

-2021-2: -2.56 to +1.01

-2022-3: -0.66 to +0.22

————

What kind of PNA are you expecting in Jan?

This isn’t a new report but I just saw it and it has the latest Jamaica death toll:

Death toll from Hurricane Melissa rises to 45 in Jamaica, with 15 others still missing

The death toll is expected to rise, with officials still trying to reach two towns that remain cut off since the catastrophic Category 5 storm made landfall in western Jamaica on Oct. 28.

Helicopters have been dropping food and other basic supplies in those two communities, said Alvin Gayle, director general of Jamaica’s emergency management office.

He said the storm has displaced 30,000 households, with 1,100 people still living in 88 emergency shelters that remain open.

https://apnews.com/article/jamaica-hurricane-melissa-haiti-cuba-killed-deaths-77db005a55d415ae84b74f6680769273

29 minutes ago, wncsnow said:

Let's bring him on and ask him

 I took your advice to find out instead of assuming. Since he doesn’t post here, I knew I had to ask him how he’s done with snow in NM. His answer:

We’ve done okay ish I would say overall, we have yet to have any snow though. Just had our first precipitation event since early October a few days ago. Earlier this year it snowed on my birthday so that was nice. Our last 4” winter storm warning worthy storm was back in 2015, tho Feb 2021 got close in a few spots. Any accumulating snow is a really big deal down in the Desert Lowlands & people go crazy over it here like they do in the southeast. 

The climatology here since the early 2000s is roughly about the same as places like Charlotte, NC. It used to snow a lot more here several decades ago but our average has cratered.

 ————

 So, it wasn’t bad like I thought, but by no means has he been racking it up either. It sounds in between. He hasn’t gotten that much, but they normally don’t there.

4 hours ago, wncsnow said:

The SW has racked up the last 5 years. This year is off to a good start for them 

I don’t think met. Eric Webb has been happy with how his abode in NM has done in recent years (since he moved there) based on his posts.