Model discussion - hunt for cold Christmas period 2021

[PiscesStar]

37 minutes ago, bluearmy said:

Certainly looks quite mobile ridge/trough but with the potential of an Arctic high in an advantageous position, that presents opportunities 

also the euro heights seem to be less sustained on the eps this morning in the mid term and fi 

Three large clusters in extended - one is very HLB.  None seems to show a specific feature on our side of the NH 

Yes, it's those iberian heights which are a pain. Wait til summer damn it.. 

[SLEETY]

\Woeful output at the moment for cold,if global warming is the cause of these failed attempts at cold weather in the winter then how is it that in other seasons you get the perfect pressure patterns for cold and snow if it was winter.

Last April was dominated much of the month by a Greenland Blocking High,even MET did video about it,,similar in May too,then everything just reverts to usual patterns for most of the 3 months of winter,what is actually happening???

Edited December 27, 2021 by SLEETY

[Uncertainty]

Caution: Cherrypickers spotted in the area ahead…

GEFS 348

GEPS at day or so before

 

EPS clusters

Cluster 2 is indeed very blocked, good to see these options have returned as they were mostly absent for a few runs. The very +NAO option is there as a strong minority.

Overall there is a weak signal for higher heights to the W/NW around day 12-15. Not unrealistic given the next bout of tropical forcing. We have another +EAMT event occurring and that should propel the GWO into the higher AAM phases. It should also at least delay any return to the low frequency forcing state. I’m also a bit surprised that we’re not seeing more of an impact on the upper strat, especially given the considerable wave 2 pressure coming into the reliable time frame

Athough today’s GEFS are considerably toastier than for the last few days, though very ‘displacementy’?
 

Opinion alert: We really need this warming  signal to increase sharpish. Should this effort fail I personally believe the SPV will recover big time and couple with the lower levels. Similar thing happened in v early 2020 and we know how that ended up! 
 

Just a bit of cope/hope then for coldies whose hopes were so cruelly dashed over the past few weeks.

Not that I trust it in the slightest, but it will be interesting to see what the EC46 does with this signal in weeks 3 and 4. Hopefully it builds upon it rather than squashing it. 
 

[Frosty.]

It’s business as usual, I’m chasing phantom  Gfs cold  charts towards mid Jan and England are getting massacred in the cricket!  

 

[johnholmes]

Little signal for any change for two weeks if the 500 mb anomalies are anywhere near correct

ECMWF/GFS DAY 8-10 MEAN 500MB HEIGHT COMPARISON

WWW.METEO.PSU.EDU

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

[weathercold]

21 hours ago, Ed Stone said:

And, also for balance . . . when the GFS started to suggest that the cold spell wasn't going to be of historical proportions, it was instantly 'binned'?

[weathercold]

Exceptional warmth this week for the time of year. Temps reflective of late spring/early summer quite astonishing. Night time temps of 14 degrees in London at the end of Dec is quite something. There is no disputing global warming is causing these extremes we now experience more regularly now than ever before.

As for this winter- I’m not one to hopecast and like to call it how I see it - my thoughts are we will need a SSW to save our winter this year - personally so many of the really positive signals seen in Nov and Dec have readily evaporated sadly.

Only 3-4 months until Spring …whilst the weather this week will make you reach for the those t shirts and shorts believe it or not we are actually meant to be in mid winter -:)

[SLEETY]

uk winters now  are basically 6 months  of Autumn weather and temps ,but nobody can explain why we get the  decent winter pressure charts outside of winter

Edited December 27, 2021 by SLEETY

[Iceaxecrampon]

1 hour ago, Speedbird said:

What's that got to do with anything ?

Are you suggesting that because past charts were inaccurate that current/future modelling will be inaccurate too ?

Jees . . .

What is Chaos Theory? – Fractal Foundation

FRACTALFOUNDATION.ORG

Try this  - as I said previously

I'm done.

[Iceaxecrampon]

4 minutes ago, weathercold said:

Exceptional warmth this week for the time of year. Temps reflective of late spring/early summer quite astonishing. Night time temps of 14 degrees in London at the end of Dec is quite something. There is no disputing global warming is causing these extremes we now experience more regularly now than ever before.

As for this winter- I’m not one to hopecast and like to call it how I see it - my thoughts are we will need a SSW to save our winter this year - personally so many of the really positive signals seen in Nov and Dec have readily evaporated sadly.

Only 3-4 months until Spring …whilst the weather this week will make you reach for the those t shirts and shorts believe it or not we are actually meant to be in mid winter -:)

And the GFS had us in the middle of Narnia for the 29th Dec last week.

[mountain shadow]

15 minutes ago, Iceaxecrampon said:

And the GFS had us in the middle of Narnia for the 29th Dec last week.

Not just the GFS, it's whole ensemble as well. 

Thanks to the hardcore who keep posting when there is very little of interest. 

[Premiere Neige]

24 minutes ago, weathercold said:

Exceptional warmth this week for the time of year. Temps reflective of late spring/early summer quite astonishing. Night time temps of 14 degrees in London at the end of Dec is quite something. There is no disputing global warming is causing these extremes we now experience more regularly now than ever before.

As for this winter- I’m not one to hopecast and like to call it how I see it - my thoughts are we will need a SSW to save our winter this year - personally so many of the really positive signals seen in Nov and Dec have readily evaporated sadly.

Only 3-4 months until Spring …whilst the weather this week will make you reach for the those t shirts and shorts believe it or not we are actually meant to be in mid winter -:)

3 - 4 months is a whole season though. And it may be mild but 12°c and pouring rain definitely doesn't make me want to reach for shorts and a t shirt!!

[Anthony Burden]

Morning all,Gem ensembles mean looking mild for  9 to 10 days but some ensembles starting to drop into

the cold scenario,always remember things change suddenly when weather is concerned.

 

 

[Methuselah]

9 minutes ago, mountain shadow said:

Not just the GFS, it's whole ensemble as well. 

Thanks to the hardcore who keep posting when there is very little of interest. 

Maybe it's time we altered our definition of 'binworthy', then. Charts that show us nothing but what we want to see being the first for consideration?

[karyo]

9 minutes ago, Premier Neige said:

3 - 4 months is a whole season though. And it may be mild but 12°c and pouring rain definitely doesn't make me want to reach for shorts and a t shirt!!

The thing is spring is not 3-4 months away. The days are already growing now and by February the sun gains enough strength to melt any snow that settles (apart from the heavy falls which are rare). This has always been the case but the warming trend that we are experiencing practically makes February the start of spring.

Edited December 27, 2021 by karyo

[Tamara]

On 26/12/2021 at 23:34, Singularity said:

Many thanks for the update @Tamara. May I request clarification on one aspect - is the return of a westerly regime to the Atlantic sector (via larger fall in AAM) something you’re expecting to see after a +AAM orbit in the first half of Jan, or sooner?

I’ve been anticipating another +AAM cycle on the basis of slight eastward progression to the MJO without much opposition from the Walker cell, which as far as I can see no longer aligns to a La Niña standing wave. Hence my level of interest in the possibilities involving the HLB in the first half of the month.

Hi there The intraseasonal tropical cycle has supplied the wave driving to overlay the walker cell for sure, but looking at the SST arrangement in the Pacific there remains plenty of fuel for the standing wave to not move far yet (keep imprinting and firing convection) from Indonesia into the West Pacific (consistent with a La Nina type feedback).

The stalled intraseasonal MJO cannot sustain indefinitely and without any immediate evidence that the present westerly inertia c/o the MJO is altering the spatial arrangement of SST's (and upwelling) in the Pacific in the near term , then as soon as the effects of the intra-seasonal dampening are removed then angular momentum, (currently operating at close to 2SD (standard deviations) above average (and a considerably precipitous  El Nino'ish disconnect to the base state) will likely undertake a sharp correction.

It could indeed be that La Nina is peaking and that transition will start occurring by the Spring, but on present evidence, the feedbacks remain for a while yet with the walker cell well west of the dateline and the intraseasonal MJO is/has been massively blind-siding the reality while it has been stalling at apparent high amplitude.

Timing of all this (ie when the intraseasonal signal loses its grip is difficult based on the very extended stall). But, in synoptic terms, the next minefield for the numerical modelling will be when this happens and in the absence of any steering within the stratosphere to the troposphere (very much the other way around) then it seems logical to think that a traditional +NAO/+AO is a probabilistic outcome.

Evidence to the contrary can and may emerge to change this, but until or if that happens then this is the watching brief in my opinion.

[Alexis]

53 minutes ago, weathercold said:

Exceptional warmth this week for the time of year. Temps reflective of late spring/early summer quite astonishing. Night time temps of 14 degrees in London at the end of Dec is quite something. There is no disputing global warming is causing these extremes we now experience more regularly now than ever before.

As for this winter- I’m not one to hopecast and like to call it how I see it - my thoughts are we will need a SSW to save our winter this year - personally so many of the really positive signals seen in Nov and Dec have readily evaporated sadly.

Only 3-4 months until Spring …whilst the weather this week will make you reach for the those t shirts and shorts believe it or not we are actually meant to be in mid winter -:)

Touching 16C, and a minimum of 13C is more likely. 
I'm no climate change denier, but a lot of winters have such a mild spell. 1920 saw the mildest Christmas period on record.

[Ali1977]

Day 8 from the last 2 GFS runs are quite similar, so broadly expect to have something like this for then. It’s hard to see a quick route to cold from here, those heights from Alaska do deliver quite a punch, so we’ll just have to see where that goes and hope for the best

We may be very warm, but the deep cold isn’t far to our NE should we get the flow from that direction at any point!! 

Edited December 27, 2021 by Ali1977

[Mariescb]

17 minutes ago, karyo said:

The thing is spring is not 3-4 months away. The days are already growing now and by February the sun gains enough strength to melt any snow that settles (apart from the heavy falls which are rare). This has always been the case but the warming trend that we are experiencing practically makes February the start of spring.

Technically yes the sun is stronger in February but you are talking about transient/marginal snowfall, the snow is never going to melt if we are locked into a cold pattern. Many cold spells over the years have happened in February. 

If anything I would say that December has become an autumnal month and the beginning of February is now mid winter. Certainly in my lifetime, February has had more cold spells than December. 

The failed chase just gone would have been an unusual, not expected bonus but give it a few weeks or so and then winter is more likely to kick off imo. We shall see what happens

[SLEETY]

32 minutes ago, Anthony Burden said:

Morning all,Gem ensembles mean looking mild for  9 to 10 days but some ensembles starting to drop into

the cold scenario,always remember things change suddenly when weather is concerned.

 

 

Seems to change suddenly to mild, like lask week, quite often, rarely seen it flip mild to cold over the decades, just have to sit this out a while. 

It's not as if January has acted like a winter month anymore check out the January Cet since 80s.

February not much better might be start of Spring AGAIN before winter arrives. 

[Singularity]

Thanks for the elaboration @Tamara. Perhaps I’ve overestimated the extent to which the La Niña supports have been broken down, though I’m going to hold on to some hope that the C Pac has been modified enough (thermocline slope altered) for a more muted impact on the high frequency tropical cycle and AAM tendency.

Timing-wise I’ve been thinking of final third Jan for a bigger AAM drop that shifts the cycle to either a negative-positive one (full GWO orbits with associated variety of  weather regimes) or a fully negative one should the SST arrangement in the tropical Pacific prove still sufficient to reinstate the La Niña base state.

Before then, a shot at some manner of HLB spell for the middle third of Jan. Ideally with an assault on the polar vortex while it’s weakened by the wave-2 attack taking place across NYD... but the modelling is very ‘if, maybe’ on the matter.

[Ali1977]

Day 9, the strat is certainly warming up - maybe this mini warming will fall in line with AAM/MJO feedback and smash the vortex to smithereens towards mid Jan!! 

 

 

Day 10 lift off to Greenland, maybe !!

Edited December 27, 2021 by Ali1977

[Methuselah]

RAMP Alert!       

[blizzard81]

22 minutes ago, Ali1977 said:

Day 9, the strat is certainly warming up - maybe this mini warming will fall in line with AAM/MJO feedback and smash the vortex to smithereens towards mid Jan!! 

 

 

Day 10 lift off to Greenland, maybe !!

Could this be the winter of large swings in the models and forecasts. We've had the swing to mild so we are now awaiting for the elusive swing to cold. I certainly wouldn't rule it out. 

[blizzard81]

The 06z is listening to me