Summer 2025: Model Output Discussion Highlights

[phil nw.]

 LRD  *Stormforce~beka*  Georgina

Hi folks,

I see Kyle has given an explanation above but i will to try and cover the link with the MJO and the Rossby oceanic wave which has affected it's movement eastward and an overall explanation of Rossby waves.

We can get Atmospheric or Oceanic Rossby waves.They are slow moving movements of the atmosphere or the ocean caused by the rotation of earth.

They transfer heat  around the globe  and help shape the jet stream and  weather patterns .Sometimes referred to as planetary waves.

In the case of the MJO which is an area of tropical convection/thunderstorms now situated over the tropical Maritimes(Indonesia) it has become slow moving as it has hit the colder waters brought by a westwards Rossby wave.

We can see from the sst map where the cooler waters further east are.

I hope in my rather simplistic way this has helped but for further reading and a video here is a useful link. 

/apple-icon-144x144.png

What is a Rossby wave?

OCEANSERVICE.NOAA.GOV

---

Oceanic and Atmospheric Rossby waves are the natural result of the Earth's rotation and can change weather conditions around the Earth.

 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5186287

[Cambrian]

This is becoming extremely interesting now - the models homing in on what could be a Christmas week reset to the Northern Hemisphere pattern, in time for the mid-winter period. 

The 12z GFS op is typical of the output trend. We go from day 3, with the core of the PV over northeast Canada / Greenland.

 

By day 8, the PV is served as a huge Arctic roll, stretching from the Pacific through the pole to the Atlantic. There is a 945mb low over the Aleutian archipelago. This is shown better on the anomalies chart.

 

This, coupled with the negative to positive heights switch over northeast Canada, is what is providing the forcing for the pivoting of the PV west. A great contrast with the heights over the UK and Ireland.

By day 12, the transfer to the Eurasian side is complete. But it takes a few days more for alignment of the trough through Scandinavia and the squeezing out of the European heights, here by day 16, allowing Arctic air to flood south. 

  

The transfer is well supported by the 12z GEFS mean, days 3, 8, 12 and 14 (it gets a bit more fluffy towards day 16), the trend comparing favourably with the op above. 

   

The process, if it transpires, takes two weeks and will no doubt test patience here, but this change is being extensively telegraphed and in seasonal terms could prove extremely timely.

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5186333

[Penrith Snow]

Iberian Heights are again the problem this winter, last winter was the same with favourable background signals overwhelmed by huge high pressure to our south.

The promising January 2024 cold spell was abruptly ended by a sudden rise in pressure over Spain which persisted for 2 months resulting in the driest Spanish winter on record with severe drought.

If this expansion of the Hadley Cell at our latitude is a result of GW we are in real trouble no matter what the MJO and other tele connections indicate.

Back in the 1990s and 2000s it was the Bartlett High that was the curse of winter, we now know this was just the baby which grew into the Iberian Monster.

Andy

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5186439

[Duane S.]

 Battleground Snow  A definate step in the right direction.

Holding +1 sigma amplitude going into the Pacific  (instead of what was forecast) would likely be enough to get better mid-Atlantic ridging showing up in the forecasts for early Jan.

Having crossed into P6 without as much interference as expected  (+ the supressed area largely out into the IO & likely to intensify over the Maritime Islands) makes me wonder if the forecast dip into the COD is now also as likely to happen.

As always, a waiting game...

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5186675

[WYorksWeather]

Thought it might be of interest with reference to Euro heights to see how much more common these are than in years past. To test this I've created a few charts using the NCAR/NCEP re-analysis tool.

These are 500mb height anomalies for winters compared to the 1991-2020 average. Starting with the most recent 10 winters, you can see an anomaly of about 25m (2.5dam) centred over Iberia for 2015-2024 (we mean the ending year of the winter here, so 2024 is winter 2023-24).

What happens if we go further back? Here is 2005-2014, which included a number of colder winters. Actually a strong negative anomaly over Europe - around -30m (3dam).

Another 10 years back. No real signal for 1995-2004.

1985-1994. This included some mild late 80s winters, but again only an anomaly of 10-15m (1-1.5dam) relative to 1991-2020, so nothing like as strong as the recent 10 year Euro height anomaly.

Further back again, 1975-1984. -30m (-3dam).

Similar for 1965-1974, but even stronger negative anomalies, around -50m (-5dam).

Going back again to 1955-1964, we have a -45m (-4.5dam) anomaly.

Finally, as far back as we can go, using a 6-year mean from 1949-1954, we have a -40m (-4dam) anomaly.

Summary

I think overall it's pretty much clear what is happening here. You can almost divide the period back to the start of the reanalysis into three distinct eras.

During the first era, from the late 40s through to the mid 80s, the Euro heights anomalies were far below what we expect today, with some interdecadal variability, but all well below even average 1991-2020 climatology, let alone what we've seen in the last 10 years.

The mid-late 80s through to the mid-2010s is another distinct era. Some of the late 80s and early 90s winters had more modern characteristics, though the strength of Euro heights was still not equal to that we see today. There was also a better period from 2005-2014 for cold weather, which coincides with lower Euro heights. Overall, a bit of a mixed bag during this period.

The final era is the one we are in now. You can clearly see that something dramatic has happened. A +2.5dam anomaly is very substantial, and shows a huge change, especially compared to the cold winters of years past from the 60s, 70s and early 80s, when the decadal anomalies were as low as -5dam. The last 10 winters have seen a very substantial tendency towards strong heights to our south, weaker than average pressure to our north, and strong +NAO type patterns being more common.

This very much backs up the case a lot of people have been making that something has changed beyond just global background warming - this is quite a major synoptic change. It also in a slightly more informal and accessible way backs up some of the articles people have been posting on the expanding Azores High.

Anyway, I hope that me taking the time to take a look at this has been useful.

 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5186771

[Ciarán]

 Johnp I'm very bored, so let's see if we can estimate what weather this synoptic pattern would bring on for example, the 20th of July:

Ambient 2m temperature:

We can estimate this fairly easily assuming 14 degrees uppers and typical environmental lapse rate of 6.5C/km as well as no inversion.

Temperature change = height x lapse rate

1.498 (for 2m temp not 0m/ground temp) x 6.5 = 9.7 celsius.

14 + 9.7 = 23.7 celsius ambient temperature, but this is without any sunshine.

Solar Energy Transfer:

We'll assume this is in London at 51 degrees north.

90 - 51 = 39 + 20.5 = 59.5

Solar declination angle is typically around 20.5 degrees in mid-July, so I added this on.

Solar constant is 1361W/m^2

We have around 8 hours of direct sunlight so lets say 1361 * 8 * 3600 = 39.2MJ/m^2.

Solar heating:

Change in temperature = 27.4x10^6 (solar energy absorbed) / 10000 (standard column of air has mass 10,000kg) x 1005 (specific heat capacity of air in J/kg)

^T = 39.2*10^6 / 10000 * 1005 = 3.9 celsius.

23.7 + 3.9 = 27.6 celsius, but for the sake of urban heat island lets round to 28 celsius.

So not exactly mid 40s.

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5186721

[Uncertainty]

I’ve seen worse ec46 updates 

Much improved mjo progression: already in phase 6 then a decent swing through the cold phases.

And no, I’m not taking it in iSoLAtioN.

Aside from the next day or two, The regimes chart is free from +nao dominance throughout.

Week 2 is similar to before with heights to the nw but sadly - as covered in detail on here tonight - also by high slp to the se too; Negating cold potential.

Week 3 though loses the euro high anomaly and just hints at a better pattern developing.

We also have some odd developments in the strat, perhaps even a CW according to Dr C and he showed some research suggesting they can correlate to a GH and a colder euro pattern. As @bluearmy has suggested, it’s maybe not a coincidence that the nwp is playing around with better FI patterns to our NW in early Jan given the emergence of a strat ridge in the locale.

So hardly a disastrous position to be in during this crucial period. The word that comes to mind to me is intriguing. 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5186825

[WYorksWeather]

Bringing things back to the present, here are tonight's EC 12z clusters.

Days 3-4

The brief north-westerly sets up for the weekend.

Days 5-7

Not worth individual commentary on these either to be honest - all three clusters look mild and dry from days 5-7 (23rd up to Christmas Day).

Days 8-10

Cluster 1 (67%) has high pressure generally centred just to the south of the UK. Some signs of a brief low pressure incursion into the far north of the UK at day 9 bringing some more unsettled conditions, but a general mild and dry theme continuing. Heights rising over Greenland, but no UK cold with the strong Euro high.

Cluster 2 (33%) has high pressure slightly further north. On balance probably still fairly mild, with the mild air wrapped into the high initially, but probably cooling slightly as the link to Iberia is cut-off by day 10, with more of a south-easterly. As with Cluster 1, heights rising over Greenland, but UK cold not in the offing with that high to the south.

The OP was in Cluster 2.

Days 11-15

Only one extended cluster again, so again reflecting the ensemble mean. High pressure remaining in control at day 11, then a slight weakening of the pattern. By day 15 it just generally looks quite messy, with a weak attempt at Atlantic ridging probably about to be shoved aside by an Atlantic low, some troughing to our east, but still heights to the south. Probably mildest in the south, somewhat cooler further north, and relatively unsettled. But quite a difficult chart to read, to be honest.

Summary

Pretty clear picture - mild and relatively dry conditions absolutely dominant up to day 10 and even beyond in the presence of a large Euro high. Beyond that, still not very hopeful, with even the extended pattern all the way out to day 15 not very conducive for cold. About all you can say is at least the signal for Euro heights weakens a bit, but as long as that positive anomaly is there we're probably on a hiding to nothing from a UK cold perspective.

Overall, still in a mild pattern for the foreseeable. Any change before New Year is becoming less and less likely with every passing day. As always though, we can't write things off beyond the range of the models. Short term pessimism from me definitely at the moment, but still keeping an open mind about January.

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5186814

[WYorksWeather]

 blizzard81 Managed to find a different re-analysis product I can plot on the same website, which goes back to the mid-19th century. It should be noted that these anomalies are relative to 1981-2010, and since it's a different re-analysis probably not exactly comparable to my earlier figures, but I doubt there would be any major differences in the later years.

In relation to your question though - prepare to be surprised. There's still a negative height anomaly to our south relative to 1981-2010, and in fact I've done every decade of the first half of the 20th century to show that it doesn't really matter which you choose. The core of the negative anomaly in Europe ranges from -20m (-2dam) to -35m (-3.5dam).

The key is probably the lack of consistency. Looking through the data, the 1920s and 1930s did have some mild winters, that perhaps would have had characteristics closer to those of modern winters, but probably not enough of them to reflect a positive anomaly on these charts at the scale of an entire decade.

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5186856

[Catbrainz]

Speaking of those insightful charts posted by other members I will break down with NOAA all winters since 2015

 

 

 

 

 

 

 

 

 

Ironically 2023/2024 does look good for a cold winter, youve got a high over Greenland and low pressure over NE Europe but that Iberian high ruined things. (Plus I think separating the Euro low from the Atlantic low would have helped get cold too). 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5186866

[KyleHenry]

 bluearmy Definitely possible. SPV weakest at that point, as always the displacement and elongation of SPV becomes a hinderance. Viewing the TPV in GOA region, there is no LP movement for the uplift, only slack HP.

This one looks tropospheric lead, -AO being produced from a different vector via Canada. Thats also dependant on variables, hight of HP and strength of HP central Canada region.

Unique set up, if Canada holds then TPV airmass floods Europe.  

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5187024

[bluearmy]

 northwestsnow the Atlantic trough around the Azores doesn’t help in this respect 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5187189

[Bullseye]

Interesting that despite the dark purples of PV setting up over Greenland as currently modelled, this should shift away from Greenland by end of the month. Now I'm sure last week, some where writing off January or saying we would be weeks away from anything remotely interesting with PV set up over Greenland. Can learn from this and while it may not bring colder weather, it does show how quickly PV can drain away from Greenland. 

 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5187245

[Mike Poole]

ECM 46 looks much better regarding the MJO.  

Keeps out of the COD through 6 and the orange cloud at day 10 is pretty much all decent amplitude 7.

Zonal winds:

Two things here, first the SSW chances are in the ascendancy, 16ish today compared to 12 yesterday, 8 the previous day.  Second, the plummet just after Christmas Day, it will be interesting to see whether this will become more pronounced as the models make sense of some odd things going on up there.

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5187243

[northwestsnow]

 HarvSlugger 

I don't buy the bad luck stuff.

It's year in year out.

That's not bad luck,it's GW.

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5187432

[northwestsnow]

 HarvSlugger

Indeed,this has been looked at many times.

Greece/ Turkey get the benefit of +NAO and +NAO is related to GW,as we see nearly every winter nowadays, strong PV N America cold ,downstream Euro high and Europe's a bake.

Any cold air released from higher latitudes spills out on the Eastern flank of the euro heights.

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5187442

[Ladyofthestorm]

Oh my. 

Eye watering candy floss teasers of a white fluffy nature. 

I'm not sure where to begin as the evidence begins to pile in .

 

Perhaps I should start with the first piece of the jigsaw...  Something That ECM eluded too earlier on . It's significance is not only illustrating a weakening of the PV and higher pressure to our North ,  but the linkage of that very dominating Greenie high with an Atlantic ridging.  Cue Northerly regimes 

 

Goodbye Atlantic conveyor belt of wet and windy doom. 

Look at the NAO from a raging PV platform,  absolutely  incredible. 

Perhaps it's the ensembles remember trend is your friend watch the mean . Operational is an outlier. 

Then of course the  marmite of teleconnections the MJO 

Heading nicely into phase 7 &8, as someone else suggested earlier on ( Maybe Bluearmy)  we missed the COD, significant for this next stage.  High pressure over Greenie opens the Nly floodgates , that makes sense and agrees with the pressure charts  above . We would be fools to dismiss this signal. It's the best one we have had for years. 

 

That's a sudden slowdown of the Zonal winds , yes to below the average , but look how far it has fallen . Then those mouthwatering reversals . I would propose even a weak SSW would cause sufficient disruption to reverse this. 

 

All to play for peeps. I actually still believe something is brewing and its not the Euro high of doom. 

 

 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5187767

[Mike Poole]

Today’s zonal winds:

SSW count about 22, up from 16 yesterday.  The key thing is whether the strat vortex rebounds after the initial slowdown around New Year or whether its decline continues.  Jury out at the moment, but should become clearer in the modelling quite quickly.

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5187780

[phil nw.]

A decent set of gefs this evening.

The 500 anomalies compare now to the end frame we can see a big change.

 

We switch to a -ve AO and the gradual draining of heights from Europe.Not yet a complete evolution to cold but a promising trend towards it.

A look at the graph

Temperatures trending below average with the gfs op run quite a warm outlier later on.

This is something many of us are looking for in January given the weakening strat  forecasts and the movement of the mjo into the Pacific and out of the warmer phases.This is now in phase 6 and i believe this starting to show up,allowing for the lag time.

A more optimistic outlook from me but always with the caveat that like everything tied up with the models these are all forecasts,however this is the trend us coldies are looking for after this protracted milder spell.

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5187828

[WYorksWeather]

EC clusters below. I should have more time for posting over the Christmas - New Year period. Working up to Christmas Eve but off from then to 6th January.

Days 3-4

High pressure toppling into the UK by Christmas Eve, turning very mild.

Days 5-7

Cluster 1 (51%) has high pressure remaining centred just east or SE of the UK. Dry and remaining mild or very mild, especially further north.

Cluster 2 (49%) is very similar, except that high pressure is slightly further NE. Becoming less mild by Boxing Day and beyond into day 7, but still near to somewhat above average.

The OP was in Cluster 2.

Days 8-10

Only one cluster at this range. The representative member for the ensemble mean is P29, which has high pressure to the NW but also over the UK. Quiet weather conditions, remaining relatively dry, with temperatures probably near average.

Days 11-15

Only one extended range cluster. The representative member for the ensemble mean is P31, which has high pressure over and to the NW at days 11 and 13, remaining dry and anticyclonic, but on the colder than average side with north-westerlies. Turning more unsettled by day 15, with a possible northerly. Still some trailing heights to the south, so probably less likely that any cold push will make it all the way to the south of the UK.

Meteograms

Decided to add the ECM meteograms tonight since otherwise it's hard to glean much from the clusters when we only have one option at days 8-10 and days 11-15.

Using Reading as a proxy for the south, the meteogram shows mainly dry and cloudy conditions for the next 10 days. Temperatures consistently above average except for the brief north-westerly over the next couple of days, especially so by night given the cloudy skies. A very mild Christmas Eve and Christmas Day predicted.  The wind direction is mainly westerly or south-westerly. Beyond day 10, signs of more unsettled weather, but still on the milder than average side.

Using Aberdeen as a proxy for the north of the UK, it's a very similar trend to Reading for the first 10 days, with some variations as to detail. Given the position of the high pressure, temperatures for Aberdeen are even more exceptional relative to average than for Reading, with the predicted maximum temperature on Christmas Eve equalling the 99th percentile of climatology, and an exceptionally mild night for so far north with an overnight low of above 10C. Cloudy, relatively dry, winds mainly from the west or south-west.

However, there is a more substantial difference beyond day 10, with signs of an increased probability of north-westerly winds, and consequently the temperatures do drop away, with the mean falling below average by both day and night around New Year. Not deep cold, but probably enough to provide some interest, especially for areas with elevation further north.

Summary

From what we can see of the first 7 days, the picture is largely unchanged. A significantly milder than average period overall, with the peak on Christmas Eve, which could be exceptionally mild, perhaps record-breaking. Remaining mild beyond that even with high pressure slightly further north, though exactly how mild depends on the details of the positioning of the high pressure.

The clusters become fairly unhelpful beyond day 8 with only one option, but here the meteogram output is useful and largely backs up my reading of the clusters. Generally mild weather continuing across most of the UK through to day 10, and generally fairly quiet conditions with a lot of dry weather, albeit cloudy.

Beyond that point, we see more of a north-south split. Signs that the north may be exposed to more of a north-westerly, with heights over Greenland and temperatures falling below average. Further south though, the Euro heights maintain some influence (albeit not as great as over the next 10 days or so) which is likely to prevent any cold air reaching the south.

Overall, a mild rest of the year pretty clearly on the cards now. Early January is too far to say with any confidence, but possibly some interest further north. I'd be less confident about anything further south as long as that Euro height signal stubbornly refuses to go away. 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5187839

[nick sussex]

The pattern upstream becomes slow moving as the jet weakens .

This due to the departure of the PV from the nw .

So changes are slow . 

It’s only when the jet strengthens that the pattern starts to move east . This by way of the PV transferring a lobe west across northern Greenland .

 

Following on from that the likely move into phase 7 on the MJO develops a more amplified wave working east towards the eastern USA .

 

The ECM then goes onto suggest a toppling high .

 

The topple needn’t be the end because another wave upstream could develop which will draw the PV further nw .
 

 

Any amplified wave connected to the PV acts in an anti clockwise motion on that so the chart above with the foreboding looking PV turns into this .

 

Although prospects at the moment don’t look great changes are likely to take place towards New Year .

 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5188078

[bluearmy]

Clearly the evacuation of the tpv from Canada is a temporary scenario. However, we don’t know if the new year Canadian segment will become master or servant.  It does seem that the weakened jet from the rising heights over Canada does little for nw europe other than allow a strong high to establish.  The Azores low could continue to be a wild card into the distance as it chucks shortwaves northeast between ridges.  These introduce warm air into cool n Atlantic systems and bring deepening which likely helps to renew the euro ridging. 

Actually seems that the best chance of mid Atlantic ridging is after the tpv drops back down into Canada and drives an eastern n American trough (and downstream ridge).  The concern would then be whether any amplification could hold with the stronger Atlantic jet that the colder conus would drive. 

some of the NH stamps are encouraging. Some less so. The eps website not playing ball this morning. 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5188079

[Midlands Ice Age]

Reading the posts above and using my memories of years gone by, I thought this morning as to why the European high seems to be so invasive recently.

I decided that the reason was because the jet stream was weakening....

This can allow 2 things to happen.

1) we get a void with a trough stuck over the UK and NW Europe (has happened 2 or 3 times in the last 5 years..

2) we find a high pressure develops to fill the void  at the momentand moves into Europe from the south. (happening now again?)

In both cases the cold tends to be to far west... (too west based)

Thinking back to years gone by the high would develop more to the north of the UK and strengthen over Scandy before retrogressing  towards Iceland once or twice  year. It only needs a slack high over Scandy to produce the goods over here.

So why should the pattern be so west based?

It has coincided with the vortex hanging around over North America so frequently.

This year (so far) appears somewhat different - but the blocking of the jet stream has occurred too far west over the USA, and not over the Atlantic.  This has enabled the Iberian high to fill the 'void' and prosper more than we would like. 

So I think what has changed is that the ENSO cycle in the Pacific is causing these downstream changes.......  The weather patterns over the US/ Canada have been totally different this year from even a normal La Nina year. What has caused these  differences which clearly affect the amplitude of the pattern  downstream?    (and hence  us).

Is it simply that the La NIna is not strong enough to force itself on the atmosphere and hence we are seeing a totally random hemispheric  pattern driven by the fewer atmospheric waves?. 

By the way there are also very odd (and different)  things happening in both poles this year particularly in the Antarctic melt season which also could be causing these differences. (or being caused by the differences!)

MIA

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5188122

[WYorksWeather]

 thickness line Yeah I do think that's a bit of an over-reaction. I stick with the meteorological definition of winter of December to February, and it's usually accepted that temperatures really start to lift up by the second half of February, with often a tendency to more spring-like conditions (much like how the second half of August can turn autumnal).

That still gives us a minimum of about another six weeks of model watching. If we are still in this position at the start of February (six weeks from today to the 1st February) by which point we can see to the middle of February on the models, then at that point the clock is really ticking. At that stage, the last two weeks of February and early March rarely deliver much (other than a few obvious exceptions like 2018, 2013). Not impossible, but you'd bet against a major cold spell.

Much like how a major heatwave in the latter half of August into early September (rather than just a warm spell) is much less common. Only good recent example I can come up with is 2023.

For me the core mid-winter period runs from the last week in December (immediately after Christmas) through all of January and the first week of February, and I think that's reasonably well supported by the data. And at the moment, we can only see model output to the very beginning of that period. We're not even close to using it up yet.

 

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5188074

[TEITS]

Good luck to anyone making a forecast for the last few days of this year when you compare the GFS,ECM,GEM.

All i'm going to say is when you look at the differences then you need to look back and use past experience in how the models performed. Now if we were looking at a possible E,ly via Scandi HP I would be siding with the ECM. However if I look back to 2005, 2009,2010 cold spells which involved a Greenland HP then the GFS in my opinion performed much better.

So at this stage i'm slightly favouring the GFS over the ECM but I do find the constant ECM OP outliers a concern with regards to the OP  constantly much warmer than the mean.

On a different note I wish the GEFS control ran past +384. An insane cold surge spreading S across the UK!

Original post: https://community.netweather.tv/topic/101008-winter-season-forecast-and-model-discussion-commentary/?do=findComment&comment=5188610