Model discussion highlights

[mushymanrob]

33 minutes ago, Catacol said:

1980s SSWs =

Feb 79, Feb 80, Feb 81, Dec 81, Dec 85 (split), Jan 87. 6 SSWs in 8 years that had frequent cold spells. In the last 8 years we have had Feb 18 (cold that followed), Jan 19 and Jan 21 (chilly, very close to cold but didn’t quite land.) Three. Correlation is not the same as cause but the idea that the “cold” and seasonal 80s happened in the absence of strat action is not correct.

Pre 1979 data is much less available but there was certainly a Canadian Warming in Dec 62 and 8 warming events in total across the 1960s.

 

Not so sure thats strictly true though...

Febs of 79 and 80 occurred on the 22nd and 29th respecively, and werent really followed by anything other than a colder regime with the odd, short lived cold/snowy spell
Theres uncertainty on whether there was one in Feb 81, only the JRA55 has one, other suites dont and there was nothing very cold following...
Dec 81 probably caused the extreme cold of early jan 82..
Jan 87 (23rd) happened after the freeze earlier that month, and may have lead to further cold snaps, but nothing out of the ordinary?

Those from the 60's are equally as dubious, 2 of the 8 were in March and didnt lead to anything noteworthy

From the research ive done on SSWs, 1/3 have no impact on our weather, 1/3 may have been responsible for minor/localised/short lived cold spells, 1/3 were followed by a more wisdespread, longer lasting freeze of which 2013's / 2018s Beast From The East was probably the most extreme examples.

Id agree with the thought that "too much" emphisis is being put on them...

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4789811

[Mike Poole]

I think our longer term prospects for cold are in a bit of a state of flux at the moment.  I think that a scandi high as a longer term ‘destination’, which had been trending, is now receding as a possibility, more a transition towards possible heights further to the NW.  

Looking at the ECM mean, T192 and T360 - there is a trend towards retrogression of systems around the NH:

The consequences of this are varied, but

• The chances of a scandi high too far east, into Russia, are receding.
• The PV segment over Greenland, which some have been complaining about, looks to back west, giving us a bit more wriggle room there.
• The (approx) Ural high, Aleutian low signal (marked T192 chart), which has been present for some time now, will probably wane.
• This may mean that ‘fuel’ for causing the strat vortex pain may start to run out after 10 days or so, what we’ve had by then may be enough to cause a SSW, or maybe fall short.  Either way, the result is most likely to be a strat vortex displaced to the Asian side.  

I mentioned this retrogression signal yesterday in relation to the clusters, and again this morning, cluster 1 in the T264+ timeframe, shows high pressure on the move from scandi towards Greenland.

Bang on cue, the ECM control flirts with a Greenland high, T300:

I get the feeling we need some high lat block foothold before this shift happens, or it may be increasingly difficult to gain one as the help from the MJO (plus lag) disappears.  If there is a split SSW, that will be a different story, a displacement of the strat vortex will help, but we don’t want to be starting from scratch to build for cold in that scenario.  Interesting model watching continues, but I’m getting impatient to land something decent!

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4789855

[Kirkcaldy Weather]

On 12/01/2023 at 13:56, Kirkcaldy Weather said:

Very exciting times indeed I'll get onto that shortly

The snowpacks in the sierras are above levels we'd expect to see by APRIL!  

Looking like about a week more of Atmospheric river conditions before a switch in the setup, how can we tell that switch is likely? 

Again focusing on the Pacific Jet (top of image) similar to in my previous posts its still barrelling down on California 

*Also note the northwest > southeast alignment of our branch of the jet

But as we fast forward a few days we see the buckle and orientation shift in the Jet and a retraction west 

Looking closer at the conditions for the UK as we see low pressures aligned on the NW>SE Jet combining with 528 dam air this will see wintry conditions with showers of sleet and snow plus any fronts attempting to move across the UK into that air have great potential to deliver heavy battleground snow

Focusing on our Jet stream branch, we see an active jet streak 

Entrance of Jet Streaks

WWW.WEATHER.GOV

 

The one on Saturday looks very impressive

This will bring a large zone of 50-55mph gusts through Ireland, Southern Scotland and Northern England Tonight

More detailed chart of that developing storm 

Another develops hot on its heels through tomorrow and the start of the weekend 

This is a prime example of La Ninà MJO phase 8 through January  

Some more info on the Atmospheric River pattern before the most exciting part of my post

The first ever night tornado warnings issued by the Sacremento NWS area 

Stunning satellite views

Now the reasons for my excitement..

Nice MJO progression of phases 7/8/1/2

 

Here's the other setups associated with phases 8 + 1

 

 

 

 

Positive signs for a blocking pattern to set up and focus shifting to a flow from the East & NorthEast

Using my own personal method I'd expect those MJO Phases to begin transitioning into surface conditions from 23rd of Jan >>

Given Siberia is experiencing brutally low and record cold temperatures its definitely to be watched 

 

 

The Jet streak yesterday was indeed impressive as it helped the storm deepen pretty rapidly with official bomb cyclone requirements measured here

Pressure began at 998.51hpa and dropped to 973.32hpa

I know there was some pretty severe conditions around Ayrshire with some damage 

Overnight and into tomorrow Looking like some snow for northern England and I wouldn't rule out the chances of the rain turning to snow in the south east (possibly into London) 

Still positive signals going forward with extensive blocking and a potential linkup with the blocking around Scandinavia and an increasingly strengthening Pacific ridge / block.

I think the EAMT event will strengthen that Pacific ridge/ block quite impressively 

 

Another tweet within that helpful thread from Eric shows February patterns associated with La Ninà, VERY intriguing composite years in there 

2021,2018,2012,2009

The first BEAST appeared on yesterday's 00z 

 

Still believe it's worth keeping a close eye on as further extreme record cold temperatures are falling in Siberia 

Another country facing extreme cold is India with what they are naming the #Coldwave

&Asia too 

 

 

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4789939

[Eagle Eye]

I feel so lucky to be a weather forecaster, the girl that broke up with me and the girl that rejected me keep asking me for forecasts .

Going to quote myself here from a couple of my recent posts;

January 8th (ignore the fact that I literally forgot where the Aleutian region is):

"-VE EAMT event towards next week retracting the pacific jet but the intimal state of the PNA and the MJO Tropical forcing, suggests a movement towards a North Pacific trough connecting up with the Aleutian low. This may mean that we see the +VE Ural Block/BK development but also some sort of ridge/blocking over the US to mid Atlantic region and its important where that forms for our Troposphere pattern for late January/early February. Given the forecasting range, its fairly unlikely to be forecasted well yet. Its good that the signal for the Ural Block + Aleutian Low remains.

So Tropical forcing and the development around the Scandi-Ural region will be extremely important going going February but some PM air in the shorter-term is gaining some decent backing.

Clear signs of that strong atlantic +VE heights development and the resultant flow that'll likely bring cold to the UK though how strong is yet to be decided."

January 11th;

"Therefore, the progression of Wave-1 would suggest movement of the +VE anomalous thermal line to be more West allowing for the strong thermal energy Tropopause transport across the Atlantic signalling for extratropical thermal increasing of Wave-2 formation for the mid-Atlantic progression towards the Scandi-Ural-BK area.

...

At this point everything becomes complicated and affected by every other thing as without a developing Atlantic-Europe Wave, the Vortex doesn't lose it's polar-night jet signal much, instead it's displaced to over us (e.g. not what we want) but if we can get a warming Wave over the pre-mentioned area; then that should stretch the Polar Vortex and at least slow down the mean to average to below average I would suspect. Beyond that, we need the signal around the Scandi-Urals area to repeat and that would likely cause at least an attempt at a split. "

January 13th;

"The shifting of the jet might be persistent with cyclonic wave breaking linked with the eventual move towards +VE mid-high lat North American heights and so consistent with Trop-Strat coupling for a quasi-stationary link between the +VE Alaskan Block and the forcing on the Strat pattern for the Wave-1 warming. More importantly, it helps with the shifting of the warming Wave poleward and shifting the Vortex but it needs to be a much stronger secondary Wave pushing towards the Scandi-Ural region then it would be a split. Though at this range, the forecast is likely to be well off, in this situation I wouldn't expect that much of a split though as the Wave-2 in Europe doesn't look that strong but if we can get a Tropopause Eddy Heat Flux re-driving towards the Scandi-Ural region then in the forecasted situation; that's the best option."

January 14th;

"the signal for the -VE EAMT would usually suggest an extension of the Atlantic jet but given the base state of the Pacific, it may enhance retrograde WAA into the East of North America whilst extending the Equatorial Atlantic Jet and backing the Eurasian feedback to affect the high pressure cell expansion into SE Europe. Theoretically, that creates the backing for a Scandi based Scandi-Ural Blocking signal"

... 

Forecast (ish) now;

That retrograde signal for that continues to show with poleward heat transfer and abnormal mass transport. This should lead to vertical heat transport though where and when depends on the speed of Rossby thermal transport and the energy released/held in planetery waves via thermal Eddy transport and the ability of the Tropopause to vertically transport the Eddy heat flux.

The reaction in the Troposphere seems a little too quick for my liking. Not necessarily because it's timing is off but because it means that it'll be another wasted Ural Block as the transition of the Pacific Wave is just a little too slow for it to be Wave-2 but it will continue to strengthen Wave-1 significantly to really put pressure on the Strat (ignore that it's the 12z run for Eddy heat flux, 18z hasn't loaded for me yet). 

What's important to me is that we keep up that signal for some sort of Scandi-BK Blocking up fairly well. Given a good transition of Wave-1 towards North America by early February then that Trop signal will really give the Strat a good Wave-2 to deal with but right now the Wave-1 seems contempt with staying over Eurasia-Pacific. So looking at the bigger picture and it's the development of the Aleutian low that'll be important of the transitioning of Wave-1 towards the Pacific-North American area. If we can get that sorted out properly then we really could be in business. A Scandi-BK high and Aleutian low combination is one of the best drivers of abnormal Stratospheric circulation and if I remember correctly can often lead to splits. Importantly though, that signal is looking fairly borderline for now so we'll have to wait and see how this truly does evolve...

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4790541

[Allseasons-Si]

On the conversation of a Bartlett high,...i did a little reseach

a mid latitude high is between 50-60 degrees north where as a bartlett high is at a lower latitude than 50 degrees north.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4790484

[bluearmy]

Question - in the ‘olden days’, the modelling was very poor approaching a sustained reversal in the upper strat. It failed to work out what was likely to happen further down in response until we got much closer to the event and in some cases, until the reversal had actually happened.  whilst we don’t see a technical ssw reversal yet modelled, we do see the flow turned above 75N beyond the 25th

the question is - did we see poor continuity of modelling last year ahead of the reversal ?  We would hope that the upgraded nwp would deal better with these events.  
 

in addition to the above, I’m also thinking about what happened in early jan. We had a disconnected trop/strat for quite some time and then the upper strat was forecast to strengthen markedly. the modelling failed to see that this would couple down - it’s accepted that the flattening of the pattern was down to the upstream polar storm and the raging jet that resulted.  But could it be that the models simply failed to cope with the pretty sudden increase in upper strat zonal flow to well above average and it’s implication lower down in the context that there was a broad trop/strat disconnect for weeks leading up to the strengthening ??

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4790672

[Mike Poole]

25 minutes ago, RainAllNight said:

The EPS clusters depict the high really wanting to go north in one way or another...

Mean at day 10 pointing slightly towards Greenland

Yes, indeed, but as I said yesterday, the danger is that it doesn’t do either!

T192-T240:

Cluster 3 favouring heights to Greenland, clusters 1 and 2 to scandi, but by T240, cluster 1 goes to UK high, cluster 2 edging NW.  Promising at this point, T264+ shows the range of things that can happen next:

Cluster 1 has heights in Greenland.  OK they get pushed aside by day 15 but we’ll let that go.  Cluster 2 forms a nice looking scandi high.  Cluster 5 ends up with a clear west-based -NAO (fortunately only 6 members), and clusters 3 and 4 the blocking doesn’t get a toehold and the pattern collapses into a +NAO.  All of these look entirely plausible, we need a dollop of luck here before the clock runs out!

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4790645

[Rain All Night]

The EPS clusters depict the high really wanting to go north in one way or another...

Mean at day 10 pointing slightly towards Greenland

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4790628

[Cambrian]

Adjustments towards delaying the end of the cold spell being picked up in the nearer term too. 

Met Office fax charts for noon Thursday - comparing yesterday’s 12z at 96h, with today’s 0z at 84h. On today’s chart, the low to the southwest is further south, not so deep and the 528 dam thickness is holding its ground further southwest. 

 

It’s clearly very hard for any systems trying to make inroads from the west all the way through to day 7 on the 0z UKMO. Days 5-7 here.
  

T850s

  

It looks like they’re getting fended off, then shunted north, with warm sectors getting squeezed out overhead. Looks like a recipe for cold air to remain at the surface with occasional bands of warm air aloft, the UK and Ireland becoming a graveyard for slow moving occluded fronts, muwhahahahahaaaaa….

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4790896

[Eagle Eye]

Good signs for the +EPO with stronger than normal high ridging towards the mid-high latitude North American Continent This appears to be due to MJO Phase 8 forcing as well as the initial extratropical in-situ SE US high. That powers up a strong +EPO return when correlated with the -VE EAMT and Pacific jet retraction. There's still some forcing for Westerly high exit and that's a similar style to how the next few days should evolve as well so further 'pulses' of Strat Wave driving though the timing is once again going to be important as the Pacific Wave tries to drive towards the Aleutian area, it could either for Wave-2 or back up Wave-1.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4790976

[bluearmy]

We go from 
This at day 6                               TO          this at day 10

  

i have very little faith in the gfs and gefs and geps working out how that affects the zonal trop flow 

The eps should be better but as I posted earlier this morning, I also doubt they will be reliable 

it may be that we have to wait for the ec op to see the event which it should be now begin to in it’s fi stages - hopefully the 46 by Thursday might begin to respond 

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4790946

[Cold Winter Night]

17 minutes ago, northwestsnow said:

EC 46 not interested in any retrogression of the High...

Not so sure about that.

Compared to last Thursday, there is an increase in probability of -NAO and the sudden increase in +NAO mid-February has been removed in favour of more blocking.
The shift from Red (Scandi/Euro blocking) to Green (-NAO) and Red, passing Purple (Atlantic Ridge) and Red does suggest a retrogression signal.

IMO it's not worse than the previous EC46, a bit different early on and a bit better later on.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791386

[Cambrian]

The 12z ECM ensemble mean at days 8 - 10 has the high steadily retrogressing west through southern UK and Ireland, heights seemingly in quite a dash to vacate Europe, surging west and building towards southern Greenland.

   

Tellingly, the northern Canadian chunk of PV is on the wane as it splits from the Svalbard chunk at day 8. The Svalbard low heights move east to the Barents Sea and begin to drop another trough down into Scandinavia.  Nothing much to stop it if the Euro heights evacuation continues, with low heights over the Mediterranean in the waiting. This is an exciting trend. It flips the whole hemisphere and potentially leaves us wide open to the Arctic from the northeast. 

The day 10 ECM mean is markedly different to the GEFS day 10 mean, where the heights don’t surge west, keeping a stronghold in western Russia, with no build to the south of Greenland, and with the Canadian PV remaining stronger. 

 

The 12z ECM mean run has I admit taken me by surprise but I can’t help surmising that if it proves to be close to the actual outcome around day 10, then this will potentially be a notable step towards a serious stab at a winter spell towards the end of the month. 

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791453

[Duane S.]

11 minutes ago, Ali1977 said:

 Supposedly this is what we want, wave 2 disruption !! No idea how to read it sorry !! Anyone? 

Decent amplitude there. I tend to find, for wave 2, above 700 down to at least 10mb can start getting interesting. This looks very interesting.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791446

[Eagle Eye]

Initially, you can see the strong poleward driving of the divergent tropopause Eddy transition which when contributed vertically should lead to a rotational transition of the Wave towards parts of Eurasia with the strongest Wave at the baroclinic dipole as it reaches the Ural-BK axis and quickly transports it's energy to the Strat Wave-1 circulation. This quickly warms the Wave causing a stronger thermal gradient and push into an unnatural axis of the polar vortex. That is the first sign of a loss of strength of the naturally strong polar-night jet component by thermal leakage into the Eastern Vortex component. Given the correlation of this with the quick Tropopause response of the lagged +PNA sharp rise over the next few days, as it moves towards neutral you would expect other patterns to start to take charge. Though it does also appear to be correlated fairly well with the MJO phase 8 lag finally pushing through with the +VE heights rise just West of Greenland. Then part 2 evolves with the +EPO development in response to a fairly weak MJO but mostly the Pacific jet retraction continuing and therefore the cyclonic wave breaking forcing +VE heights towards the E part of North America again and that re-develops/continues the poleward forcing from the UK-Scandi-BK area and given 95% of Eddy given energy rotation accounting for the flux you would expect vertical rotation of Eddy 'packets' to end up once again as a Eurasian warming. Given a longer timing signal you could make the case for Wave-2 to be dominant here though given the blocking 'tail' here you can probably expect a fairly amplified Wave-2 and perhaps with such a displacement this could split it. So with good timing, I could see a split happening despite being Wave-1 dominated but for now it's still unlikely.

Part 1;

 

Part 2;

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791687

[bluearmy]

8 hours ago, RainAllNight said:

What is meant by the "flushing down of westerlies"? I have seen @bluearmy mention this as well.

 

8 hours ago, feb1991blizzard said:

another word for downwelling, usually people are referring to the same pattern in the strat being mirrored in the trop. in this case Westerlies.

The upper strat will usually have a strong westerly flow in mid winter  - when we see a reversal, it often comes from the top down - hence those westerlies are forced downwards through the strat and into the trop - they have nowhere else to go. So a benign lower strat and trop will often see an uptick in zonal flow ahead of a reversal.  A strong weakening can also see this effect happen. whilst we don’t see a tech ssw reversal as yet, we are seeing zonal flow reverse above 75N high up and as such, there is likely to be some forcing down of stronger flow. However, the further north that reversal occurs, the more area of the upper and mid strat is left to absorb the change in flow.  it’s currently unclear what we are likely to see happen in week 2 as gfs is yet to be consistent with what it sees in the upper strat. 
 

the gfs 00z run has an example as can be seen by the area I’ve ringed on the below chart. 

 

if you check the whole run you will see how that stronger flow has been forced down by what happens above it as the flow high up goes into reverse (that’s the most comprehensive reverse we’ve seen an op run show as yet btw ) 

http://www.weatheriscool.com/prod/EPflux.html

 

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791714

[Mike Poole]

ECM and JMA both hinting at a push of heights to the NW at the end of their run, which is what I’m expecting.  

Actually, I think the most likely route to an easterly may be UK high moves first NW and later to the NE again.  Most of Europe is mild, true, but that should change now we’ve stopped blowing southwesterlies at it, notwithstanding an import from Siberia, as we are still in the heart of winter.

The move to build heights towards Greenland is seen to different degrees on the 2 clusters at T192-T240:

T264+:

The extended timeframe sees much more promise than yesterday, gone are the clusters that collapse to +NAO.  Cluster 3 holds the UK high, but you could see how the other three could lead to cold with a greater or lesser tweak, so very encouraging output this morning.  

We still need to watch carefully the details of how the strat is behaving during this timescale alongside the trop output, will be very interesting to see how this all plays out!

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791761

[bluearmy]

Don’t trust the week 2 output whilst we have notable upper strat activity within a week to ten days ….

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791868

[Nick F]

A better 06z GFS op run for the longer term potential, like 00z EC, compared to its predecessor.

Back to today, interesting small low feature bringing enhanced heavy snow showers to northern Scotland later, triggering the Amber Warning, as it displays polar low attributes. TIcks some of the boxes of criteria to be one - on T850s charts has a 'warm' core, 500mb temps below -35C, deep convection evident (lightning detected earlier) - satellite imagery shows it crossing Shetland at the moment, formed over the Norwegian Sea.

It's modelled for the circulation of snow showers to be too far out over the North Sea to affect SE Scotland and NE England as the low tracks south, though showers may clip North Sea coasts of NE England

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791938

[booferking]

Absolutely boiling up top warmest yet this run.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791932

[mushymanrob]

1 hour ago, Met4Cast said:

Displacements rarely lead to UK cold, they can, but it's far rarer than a split vortex. 

Again, im not sure thats true either..

between 1958 and 2013 there were 30 SSWs according to Amy Butler for NOAA but i dont know whether 2018 and 2019 were split of displacements, so out of the 28 i do know...

Theres no difference.

Using the Bonacina site for snow
- 8 displacements resulted in no snow
- 6 displacements did.

- 8 Spilt lead to no snow
- 6 Splits did

Of course i dont know how much or widespread these snow events were as the site doesnt give too much info.

This is only a rough guide but imho holds water.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4792020

[nick sussex]

The ECM op is one of the coldest runs but what seems to have been happening is the ensembles have lagged the ops.

The extension of the cold has been op led with the ensembles more bullish about removing the continental influence .

In terms of any cold pooling to the east we’ve seen this change between runs . The ECM pops up with a cold pool over Central Europe day 6 which then moves west sw . This misses the UK but that could change.

With highs that retrogress you can sometimes pull in a cold pool on the southern flank of that .

 

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791771

[Met4Cast]

Until the GEFS/EPS come on board for an SSW I'm really struggling to find any interest in the potential for one, even if the Det does keep producing pretty red stratospheric on fire charts, they don't really mean anything on their own, yet they are of course what gets heavily focused on.

A substantially weaker vortex than we currently have looks very likely with u-wind strength dipping below average, both the GEFS & EPS agree on this much. But in terms of a major SSW? (i.e reversal/split type, a displacement doesn't cut it for us) No strong signal & that has been the case for quite a while now, despite the noise & (unfounded?) excitement across forums/social media. 

What a weakened upper strat means for us on the ground is tricky to say, but it wont be a BFTE, I think we can be pretty certain of that.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791941

[Uncertainty]

The main thing vis the strat is that what is not presently forecast is a strong vortex dominating proceedings late Jan early Feb like most winters recently. The strat weakening is already a factor in the blocking we are now seeing in the output because it’s unlikely it would be occurring during a period of VI or under an SPV  of doom scenario. Whether we get a displacement or split is important but the location of the remnants will also be critical. Either way, I’m just glad it’s forecast to weaken. 

It is notable just how incredibly hot the gfs op runs are getting for this second burst

As a strat fan, I would love to see what happens to the vortex next. My guess is a total collapse, but it’s still out of the reliable.

The Paul Roundy charts for our forecast mjo progression however are ugly, at least those for p3 and 4.

Thus I’m rarely confident in high lat blocking benefiting us under that regime hence I do think the N U.K. high might well be what we end up with day 7-15. Beyond that it’ll be a) downwelling effects, if any and b) how quickly the mjo gets out of the IO and on its merry way back to the pacific. Right now it’s virtually impossible to reconcile them but I’m sticking to my late Feb / early March big time blocking forecast I made previously. U.K. high and then a more westerly spell in between. There are some eps/GEFS members that get more out of the extended period but not convincingly so. The back end of both models are westerly.

 

 

With the strat shenanigans however, nothing is off the table.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4792045

[Mike Poole]

28 minutes ago, Met4Cast said:

Again though, only the det. Would you take a det chart showing a BFTE at that range seriously? I'm not sure why the strat charts would be treated any differently. We know the GFS has a bias towards warming at that range (ironically the GEFS as a whole have the opposite bias).

I'm not saying an SSW wont happen, but I stand by what I said in the above post & my position is a major SSW remains a lower probability at this stage.

Events up in the strat are predictable from much further out than our weather down here.  But you will get the best predictions from the det runs this far out because they have more vertical layers than the ensembles.  We’re still too far out for the ECM det run, so GFS up to day 16 is what we have - if a SSW is to happen, the GFS op will start to pick it up consistently, ahead of the GEFS.  We will see…

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791998