Pattern The Great December Dump

[Webberweather53]

We already know it has a +PNA/-EPO bias. So, what you’re showing happens quite often with the GEFS. Nothing new here and it says practically nothing about how January will be other than it likely being mild the first few days.

In this particular case, I think this is related to the GEFS progressive bias w/ convectively coupled kelvin waves and the MJO in the Pacific & Western Hemisphere. The hemispheric z500 forecast anomaly trend throughout most of the period closely resembles MJO phase 6 in Dec during +ENSO.

 

[Webberweather53]

In this particular case, I think this is related to the GEFS progressive bias w/ convectively coupled kelvin waves and the MJO in the Pacific & Western Hemisphere. The hemispheric z500 forecast anomaly trend throughout most of the period closely resembles MJO phase 6 in Dec during +ENSO.

View attachment 28573

View attachment 28572

On the other hand this 500mb pattern will greatly increase WAFz onto the polar vortex because it projects onto the standing planetary waves.

 

[Mr. Golf]

CCKWs circumnavigate the global tropics in span of 2-3 weeks, while the MJO takes 2-3 months, this would be far from game, set, match for winter.

Regardless, we aren't getting what we want to see to be optimistic later on. At least not soon.

 

[Mr. Golf]

On the other hand this 500mb pattern will greatly increase WAFz onto the polar vortex because it projects onto the standing planetary waves.

Isotherm has been dead on so far with his interpretation. He is giving optimism if the qbo reverses negative by February. Imo, the AAM resembles a niña, which the pattern resembles moving forward. With all that said, lets go golfing!!!

 

[Webberweather53]

Isotherm has been dead on so far with his interpretation. He is giving optimism if the qbo reverses negative by February. Imo, the AAM resembles a niña, which the pattern resembles moving forward. With all that said, lets go golfing!!!

No.

The pattern going forward does not in any way shape or form resemble La Nina at a hemispheric scale esp with a deep Aleutian vortex & persistent SE Canada ridge. The -PNA is being induced by West-central Pacific convection that's reinforced by the already +ENSO base.

The appearance of a -PNA doesn't automatically mean said pattern is La Nina like. As for the -AAM, it was largely being created by +IOD which also is not consistent w/ La Nina. The upper level divergent circulation anomalies globally are also as far as they could be from resembling a La Nina & so are the corresponding SSTAs. There's nothing La Nina about this

 

[GaWx]

No.

The pattern going forward does not in any way shape or form resemble La Nina at a hemispheric scale esp with a deep Aleutian vortex & persistent SE Canada ridge. The -PNA is being induced by West-central Pacific convection that's reinforced by the already +ENSO base.

The appearance of a -PNA doesn't automatically mean said pattern is La Nina like. As for the -AAM, it was largely being created by +IOD which also is not consistent w/ La Nina. The upper level divergent circulation anomalies globally are also as far as they could be from resembling a La Nina & so are the corresponding SSTAs. There's nothing La Nina about this

And besides, the AAM is forecasted by the EPS to go positive for at least a week starting ~12/25 for the first time since June,

 

[accu35]

Isotherm has been dead on so far with his interpretation. He is giving optimism if the qbo reverses negative by February. Imo, the AAM resembles a niña, which the pattern resembles moving forward. With all that said, lets go golfing!!!

Webb knows his stuff and if you are new welcome, and we all learn from him

 

[Mr. Golf]

Webb knows his stuff and if you are new welcome, and we all learn from him

Eric is smart. I complemented him on twitter the other day. Its just interesting on what's going on currently and moving forward.

 

[Rain Cold]

Wish this look was valid for December 4th rather than January 4th. Without going down to Joe's Index Shop and pulling a 3 letter combo off the shelf, I'll suggest that whatever the state of the tropics or polar regions, we look to continue our streak of AN Decembers and rough starts to January. Hopefully, it turns around before mid-month. But if this pattern plays out, it might take a while. Good thing is, I guess it's almost as bad as it will hopefully get this winter.

 

[GaWx]

Webb knows his stuff and if you are new welcome, and we all learn from him

@Mr. Golf is a longtime member here but his name has changed slightly.

Meanwhile, the 12Z Euro maintains SE warmth on and after 12/23. Absolutely nothing new about this.

 

[GaWx]

While many folks are complaining and crying about the mild 12Z GEFS, the 12Z EPS comes in colder than the 0Z EPS and much colder than the 12Z GEFS during the 11-15 day period. Instead of the 12Z GEFS torch, the 12Z EPS has near normal temps in the first few days of Jan. Say what?

 

[MichaelJ]

Euro has as much of a warm bias in the extended as the GFS has a cold one. Ever since they changed the Euro 3 years ago or so, it has lost a lot of it's accuracy past 2 weeks

 

[GaWx]

12Z EPS 360 hour vs 12Z GEFS 360:

EPS: near normal/NO torch/wet


GEFS: torch

 

[Rain Cold]

12Z EPS 360 hour vs 12Z GEFS 360:

EPS: near normal/NO torch/wet
View attachment 28578

GEFS:
View attachment 28579

Thanks for posting these. For actual temps, agreed that it doesn't look torchy. I think many people are looking forward to a cold pattern with some chances to see snow. The actual features of both of those maps still kind of suck. Need the PV to drop SE and not park it way up north as well as better ridging out west. Those things probably work in tandem. The Euro is definitely better from a sensible weather standpoint, but there's not really a way to polish that turd pattern that both images allude to.

It's hard to know how the Euro is evolving toward the end, though. Maybe, it's reshuffling things favorably? Hopefully, that is the case. Either way, thanks for posting it!

 

[NickyBGuarantee]

12Z EPS 360 hour vs 12Z GEFS 360:

EPS: near normal/NO torch/wet
View attachment 28578

GEFS: torch
View attachment 28579

With a warm bias maybe we’re looking at token flakes here ?

 

[GaWx]

Thanks for posting these. For actual temps, agreed that it doesn't look torchy. I think many people are looking forward to a cold pattern with some chances to see snow. The actual features of both of those maps still kind of suck. Need the PV to drop SE and not park it way up north as well as better ridging out west. Those things probably work in tandem. The Euro is definitely better from a sensible weather standpoint, but there's not really a way to polish that turd pattern that both images allude to.

It's hard to know how the Euro is evolving toward the end, though. Maybe, it's reshuffling things favorably? Hopefully, that is the case. Either way, thanks for posting it!

Baby steps!
If the Bleaklies were based on the 12Z, we'd know where this EPS were heading. But unfortunately, they're based on 0Z. So, there MAY bet a lot of bleakness this evening. But keep in mind that even if bleak, they might have looked better had they run based on 12Z.

But I still wonder if they'll be bleak as they were pretty decent on the Monday run for early to mid Jan.

 

[whatalife]

Thanks for posting these. For actual temps, agreed that it doesn't look torchy. I think many people are looking forward to a cold pattern with some chances to see snow. The actual features of both of those maps still kind of suck. Need the PV to drop SE and not park it way up north as well as better ridging out west. Those things probably work in tandem. The Euro is definitely better from a sensible weather standpoint, but there's not really a way to polish that turd pattern that both images allude to.

It's hard to know how the Euro is evolving toward the end, though. Maybe, it's reshuffling things favorably? Hopefully, that is the case. Either way, thanks for posting it!

Days 10-15

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[Rain Cold]

Days 10-15

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Things seem to stay put as they get muted, presumably due to smoothing.

 

[GaWx]

Days 10-15

Thanks for posting, It is never a bad thing to have 500 mb hts below normal. And even the GEFS runs prior to 12Z still didn't have below normal 500 mb hts in the SE. These below normal heights that are lower than those of the N US resemble El Nino pattern.

 

[Arcc]

Things seem to stay put as they get muted, presumably due to smoothing.

That is the problem with the GEFS and it’s entire run SW trough. It’s clear it doesn’t know what to show even at 252hrs due to timing issues.

 

[NoSnowATL]

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[GaWx]

The last 9 Decembers have been AN at KATL. However, the following Jans were AN only 4 of those 9 times with 2 of those times BN. If folks like Webb have reason to think Jan won't be mild, there's no reason to not believe that right now.

Also, consider these facts about KATL, which went from:
- a mild 48.1 in Dec of 2013 way down to a very cold 37.0 in Jan of 2014
- a mild 50.0 in Dec of 2014 down to a normal 43.1 in Jan of 2015
- the warmest on record Dec of 2015 57.6 way down to a normal 42.2 in Jan of 2016
- a slightly AN 46.8 in Dec of 2017 down to a cold 40.4 in Dec of 2018, which included a very cold first 18 days

So, 4 of the last 6 Decs cooled significantly from AN Decs to near normal or colder Jans.

 

[SoutheastRidge]

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Where are you seeing the cold ? I see lots of warmth in FL.

 

[GaWx]

Where are you seeing the cold ? I see lots of warmth in FL.

A near normal Jan in the SE that is wet could easily support a major winter storm...well, even if it weren't wet for that matter.

A near normal January is a pretty cold month and would be way colder than this month.

 

[pcbjr]

Where are you seeing the cold ? I see lots of warmth in FL.

Who cares ... LOL

 

[GaWx]

Where are you seeing the cold ? I see lots of warmth in FL.

If you look closely, that map has @pcbjr at only a 50% chance for a mild Jan. That is very far from a lock at a mild month there even per NOAA. I think Phil knows better.

 

[pcbjr]

If you look closely, that map has @pcbjr at only a 50% chance for a mild Jan. That is very far from a lock at a mild month there even per NOAA. I think Phil knows better.

Not giving up on January ... not yet anyways ...

 

[Mr. Golf]

While many folks are complaining and crying about the mild 12Z GEFS, the 12Z EPS comes in colder than the 0Z EPS and much colder than the 12Z GEFS during the 11-15 day period. Instead of the 12Z GEFS torch, the 12Z EPS has near normal temps in the first few days of Jan. Say what?

Larry, you think because its a blip or is it picking up on the +AAM?

 

[GaWx]

Not giving up on January ... not yet anyways ...

There's no reason for you to. Why would you now? You never expected a cold December in the first place.

 

[GaWx]

Larry, you think because its a blip or is it picking up on the +AAM?

I'm hoping it is the +AAM.

 

[Mr. Golf]

I'm hoping it is the +AAM.

I will always put more stock in the eps over gefs anyday right or wrong. Btw, where can i access AAM charts or forecasts?

 

[GaWx]

I will always put more stock in the eps over gefs anyday right or wrong. Btw, where can i access AAM charts or forecasts?

Unfortunately, I don't know of any public links. For some reason, this one is super secret lol and only private services have this??

 

[Mr. Golf]

Unfortunately, I don't know of any public links. For some reason, this one is super secret lol and only private services have this??

You only get the AAM from maxar im assuming? I think weatherbell may have it. MYbe.

 

[Rain Cold]

You only get the AAM from maxar im assuming? I think weatherbell may have it. MYbe.

Joe's Index Shop has it. I've never heard much talk about it before this year, but it seems like it's pretty important.

 

[Ollie Williams]

You only get the AAM from maxar im assuming? I think weatherbell may have it. MYbe.

I don't know what site this is, or how to get it, but I saw Webb and HM post this type of chart that has an AAM graph. If you can find the source of this, let me know.

 

[Mr. Golf]

Joe's Index Shop has it. I've never heard much talk about it before this year, but it seems like it's pretty important.

Rain, the only thing it pulled up is index for stock shareholder trading lol. I think the lack of coupling between the ocean and atmosphere isnt good. If you have a link, it would be appreciated.

 

[Mr. Golf]

Figuratively speaking if the eps is correct about the AAM going positive, would it still take a while to reflect onto the models?

 

[Webberweather53]

This is far from being the best pattern in the world but I think many of us will take it over raging warmth. EPS evolution in the 11-15 makes more sense than the GEFS showing a stationary SW US trough & is more consistent w/ what we've seen the last several weeks w/ SW US troughiness in the longer term means but these troughs eventually sliding east & evolving into bowling ball cut-off ULLs that run into seasonable air masses further east.

For most of us, our climo will continue to cool off another 3F or so & by this point in early January we'll be near peak climo temperature wise. It's the type of pattern that's generally capable of being just cold enough if the timing of the waves is right, to produce wintry weather for the I-40 corridor (OK/AR/TN/NC). Severe weather is also a legitimate possibility again depending on wave timing. Regardless, our active southern jet will remain so for the foreseeable future & arguably will become even more active in the coming weeks as the West Pac tropical forcing reasserts itself & superimposes onto the increasingly NINO base state.

On a scale of 0-10 in terms of favorability for wintry weather, this kind of pattern is roughly a 4-5 imo. If we can get a nice -EPO & big SE Canada vortex at some point down the road that will obviously increase dramatically towards at least an 8.5-9 because deeper & colder air masses will become more readily available in said pattern.

 

[Mr. Golf]

This is far from being the best pattern in the world but I think many of us will take it over raging warmth. EPS evolution in the 11-15 makes more sense than the GEFS showing a stationary SW US trough & is more consistent w/ what we've seen the last several weeks w/ SW US troughiness in the longer term means but these troughs eventually sliding east & evolving into bowling ball cut-off ULLs that run into seasonable air masses further east.

For most of us, our climo will continue to cool off another 3F or so & by this point in early January we'll be near peak climo temperature wise. It's the type of pattern that's generally capable of being just cold enough if the timing of the waves is right, to produce wintry weather for the I-40 corridor (OK/AR/TN/NC). Severe weather is also a legitimate possibility again depending on wave timing. Regardless, our active southern jet will remain so for the foreseeable future & arguably will become even more active in the coming weeks as the West Pac tropical forcing reasserts itself & superimposes onto the increasingly NINO base state.

On a scale of 0-10 in terms of favorability for wintry weather, this kind of pattern is roughly a 5 imo. If we can get a nice -EPO & big SE Canada vortex at some point down the road that will obviously increase dramatically towards at least an 8.5-9 because deeper & colder air masses will become more readily available in said pattern.



View attachment 28589

Webber, do you think models would trend better if this +AAM is realized? Or woukd it not make much difference? Just curious.

 

[Webberweather53]

I don't know what site this is, or how to get it, but I saw Webb and HM post this type of chart that has an AAM graph. If you can find the source of this, let me know.
View attachment 28588

The curators of this data have basically locked it up except to a few select individuals. I know the individual who makes or provides said graph so I can ask for access if need be & provide an updated version of this.

Luckily, Ventrice has provided a similar graphic (although not the same because it only shows 250mb winds while the AAM graphic like the one above integrates through the entire troposphere). Very strong but equatorward displaced jet stream in the NH will be the name of the game going forward. Seeing -AAM/negative zonal wind (easterly) anomalies (in blue) near 60N is indicative of a pattern that's favorable for polar blocking (-AO/NAO), (obviously there's more that goes into polar blocking than that). Curious to see if we get some +AAM build-up in the tropics later though.