[Model Output Discussion - Christmas week and beyond]

Merry Christmas to you all. 

Shame the models aren't in a festive mood with some crap output. Im going to delude myself into thinking its lack of data and come 28th a raging E,ly is predicted for the first week of 2023.

[Model Output Discussion - Christmas week and beyond]

I have my eyes on something at a much closer timeframe i.e +90hrs.

A risk of a disturbance developing at the base of the low pressure  around the 28th which could intensify as it tracks NE. My interest is with regards to wind rather than snow.

Plenty to follow in the models i.e floods, gales etc. 

 

[Model Output Discussion - Christmas week and beyond]

Looks like the 06Z is going to develop into another E,ly!

 

[Model Output Discussion - Christmas week and beyond]

17 minutes ago, Don said:

I appreciate that, however, past experience shows that once a mild zonal pattern sets in at this time of year, it's normally here to stay!

Past experience shows me you are right and equally very wrong. The fact is nobody knows what will happen in Jan, Feb. I have often thought that in some respects we haven't advanced that much when it comes to long range forecasting especially when I think back to the countryfile forecasts I used to watch in the 1980s. Maybe 7-10 day has improved and maybe globally forecasting has improved. However for a tiny island such as ours then 7-10 days is the limit.

[Model Output Discussion - Christmas week and beyond]

I wish to apologise because it looks as though my predictions for the xmas period were completely wrong. However I still feel changes between +72 to +144 could occur as im still not convinced at how the models are handling storm Elliot as it leaves Canada.

[Model Output Discussion - Christmas week and beyond]

Im not as confident on the outlook as others on here. Look at the handling of the deep low pressure on the N America charts from +72 to +144 and then compare with the ramifications it has on the UK at +120 to +144. The GFS handles this low pressure very differently to all the other models and is the cause of the differences at this timeframe for the UK.

So im not suggesting a change to a prolonged, significant cold spell. However the scenario of a snow event is possible if the GFS is correct as it looks as though a low pressure may move N and bump into the colder air that has arrived over xmas.

 

[Model Output Discussion - Christmas week and beyond]

The combination of the varying operational outputs, ensemble scatter, bombogenesis that is going to occur in the USA, means im sitting on the fence for the xmas period. We have taken a step backwards but this isn't enough for me to throw in the towel just yet.

[Model discussion highlights]

Yesterday was a small step in the right direction and today its a much larger step.

What is happening on the model output is the low pressure you see at +72 in the Atlantic is now being modelled to track further S due to the forcing from the blocking to our NW. What the models are struggling with isn't just the exact track but also what happens to it. For example some models do not even have this travelling E across the country and instead takes the low S. This in turn allows the blowtorch S,lys.

However the step in the right direction is intially we thought Scotland was in the perfect position and then yesterday I thought it was N England. Today even the S could get to see some snow over xmas day. Note the ensembles for Cambs and how some members are bringing the much colder air S a few days ahead of the mean!

This happens simple because the low pressure swiftly tracks much further S and brings in the colder air. The ensemble below is a great example.

So in summary the chances of turning colder have increased and no location can be ruled out for this to occur on xmas day or before.

Original post: https://community.netweather.tv/topic/98132-model-output-discussion-the-run-up-to-christmas/?do=findComment&comment=4773751

[Model Output Discussion - Christmas week and beyond]

Yesterday was a small step in the right direction and today its a much larger step.

What is happening on the model output is the low pressure you see at +72 in the Atlantic is now being modelled to track further S due to the forcing from the blocking to our NW. What the models are struggling with isn't just the exact track but also what happens to it. For example some models do not even have this travelling E across the country and instead takes the low S. This in turn allows the blowtorch S,lys.

However the step in the right direction is intially we thought Scotland was in the perfect position and then yesterday I thought it was N England. Today even the S could get to see some snow over xmas day. Note the ensembles for Cambs and how some members are bringing the much colder air S a few days ahead of the mean!

This happens simple because the low pressure swiftly tracks much further S and brings in the colder air. The ensemble below is a great example.

So in summary the chances of turning colder have increased and no location can be ruled out for this to occur on xmas day or before.

[Model Output Discussion - the cold has arrived]

Have those providing the observational data gone on strike like everyone else? At the moment it seems these models are being run on a ZX Spectrum.

All I can say is are we taking steps towards a colder outlook or not? The answer is yes a small step towards a colder Xmas for all the UK rather than just Scotland.

I cannot even bother with beyond Boxing day right now because if the models have it wrong at +96 then these errors will only grow with each passing hour.

[Model Output Discussion - the cold has arrived]

Difficult to make any forecast at the moment as the models appear clueless to me. Some of the output from +144 onwards seems very odd to me.

All I will say is lets wait and see if the blocking to the NW will force the low pressure systems further S. As the current +120/+144 charts get closer to 0+ then this shift S is something we see very often.

[Model Output Discussion - the cold has arrived]

9 minutes ago, Weather-history said:

That's just not true. I have read Matt Hugo's analyses for some years and he will say it as it is. If its a duck, he will say its a duck. 

I haven't had chance yet to read Matt Hugo's post above but in my opinion he always provides a very honest forecast without any bias towards weather preference. Basically the complete opposite of myself

Back to the models and my word I am glad I do not have to provide forecasts to the bookmakers with regards to the betting on a white xmas. At first the UKMO was very progressive in bringing a return to colder weather from the NW but now the opposite is true. If you take a blend of all the output then the chances of cold returning and the risk of snowfall begins around the 22nd Dec onwards with the greater risk being the further N you are. Obviously Scotland is in the best position at this moment in time.

I will also add that due to the uncertainty and the fact that such relatively small changes could have a big impact. I would be cautious using some charts such as the Anomalies/Ensemble means. Stick with the operational outputs at this moment in time.

[Model discussion highlights]

Promising set of model runs this morning.

I think its pretty clear any mild spell will be shortlived before the cold returns via a N/NW,ly. Now if I remove my cold ramping hat off for a minute, I would say the outlook in the medium range is uncertain and comparing the 0Z ECM +240 N Hemisphere to the 12Z highlights the big difference between runs. I shall add that Nick S is exactly right with regards to the ECM and what would happen beyond +240.

So in summary if you're a fan of cold weather then you should be pleased with the output. The ingredients are there for a classic cold spell. What I will say is contrary to what someone was saying the output is not your typical UK winter weather patterns. Viewing the models from a N Hemisphere perspective clearly shows this.

Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4765833

[Model Output Discussion - the cold has arrived]

Promising set of model runs this morning.

I think its pretty clear any mild spell will be shortlived before the cold returns via a N/NW,ly. Now if I remove my cold ramping hat off for a minute, I would say the outlook in the medium range is uncertain and comparing the 0Z ECM +240 N Hemisphere to the 12Z highlights the big difference between runs. I shall add that Nick S is exactly right with regards to the ECM and what would happen beyond +240.

So in summary if you're a fan of cold weather then you should be pleased with the output. The ingredients are there for a classic cold spell. What I will say is contrary to what someone was saying the output is not your typical UK winter weather patterns. Viewing the models from a N Hemisphere perspective clearly shows this.

[Model Output Discussion - the cold has arrived]

Whilst I still have low confidence in the model output at the moment. I hope members have nerves of steel because it looks like the drama & hysteria of the infamous beast could well make an appearance for xmas.

[Model discussion highlights]

1 minute ago, DiagonalRedLine said:

As I’m sure has probably been mentioned by a lot people in the past, changes to a milder/less colder outlook still feels fairly comfortably far away to get too alarmed about yet (but to be fair some of the possible trends being picked up towards a less cold/milder period is getting apparent). 

With this not being too certain at the moment, then how long any less cold/milder period lasts won’t seem certain either.

For the sake of it though, I hope any break to less colder or milder conditions goes off with a snowy bang.

Unlikely to be a snowy breakdown.

Quick summary from me is the less cold spell next weekend looks like being very shortlived. The ridge of high pressure bringing the S,lys will be shunted E and be replaced by low pressure. However because of the pressure remaining relatively high across Iceland/Greenland, the position of the jet stream and the passing of the low pressure will see the UK returning back to colder N/NE,lys. The likes of Scotland will hardly notice any warming up.

Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4760170

[Model Output Discussion - the cold has arrived]

1 minute ago, DiagonalRedLine said:

As I’m sure has probably been mentioned by a lot people in the past, changes to a milder/less colder outlook still feels fairly comfortably far away to get too alarmed about yet (but to be fair some of the possible trends being picked up towards a less cold/milder period is getting apparent). 

With this not being too certain at the moment, then how long any less cold/milder period lasts won’t seem certain either.

For the sake of it though, I hope any break to less colder or milder conditions goes off with a snowy bang.

Unlikely to be a snowy breakdown.

Quick summary from me is the less cold spell next weekend looks like being very shortlived. The ridge of high pressure bringing the S,lys will be shunted E and be replaced by low pressure. However because of the pressure remaining relatively high across Iceland/Greenland, the position of the jet stream and the passing of the low pressure will see the UK returning back to colder N/NE,lys. The likes of Scotland will hardly notice any warming up.

[Model Output Discussion. 3/12/2022. How cold will it get?]

7 minutes ago, Purga said:

ECM Op was a mild outlier at the end with the main signal being continued cold - the south included.

Which suggests to me the low pressure will be further S than the ECM operational suggests.

A word of caution for those hoping for a widespread snowfall event from this low pressure. What we are seeing in the model output is signs the low pressure will remain to our S. This isn't a big surprise because we see this pattern from the models every time in these situations. Due to this a continuation of the cold temps is most likely.

[Model Output Discussion. 3/12/2022. How cold will it get?]

When you have the uncertainity like we have been seeing then its best to take all the output into account and figure out the middle ground from the extremes. You also need to look at what is more plausible using instincts and the past.

So with this in mind my current thoughts would be the low pressure will become more elongated than modelled and be centred towards Brest-Guernsey. Main areas at risk of snow is the far S with the northern extent probably 60 miles N of London but here the snowfall would be much lighter. To the north of this an area of nothing due to cloud cover from the low pressure. Further N in the clear zone would be the convective snow showers into NE England/E/NE Scotland.

Subject to change!

[Model Output Discussion. 3/12/2022. How cold will it get?]

Some classic charts from the past in the model output. The ECM really is a blast from the past with blizzards for some and those in the far S would see the very dangerous scenario of snow to rain back to snow followed by very cold temps as the low clears and brings in much colder E,lys.

Worth mentioning with the ECM for those in say N England you do not want that low to move further N. Fair enough you miss out on a blizzard but if the low is able to track that far N then its unlikely the whole of the country will see a more prolonged, snowy spell of weather afterwards

 

[Model Output Discussion. 3/12/2022. How cold will it get?]

What a bloody mess these models are in. As soon as we move away from the default weather patterns then chaos occurs and that is because in my opinion the computer models have been coded with historical data. The change in the 0Z ECM is hardly surprising as the 12Z was probably the biggest outlier I have ever seen from this model. The 0Z is at the other end of the scale with this being at the bottom of the ECM ensemble mean, but not an outlier.

Due to this uncertainity I go back to my old method of looking at this from a forecasting instincts perspective. The only problem with this though is the warming planet has changed our weather patterns but now we have the added complication from all of these volcanic eruptions. I admit my knowledge is poor in how all this ash going into the atmosphere affects the weather especially the stratosphere.

So all things considered I would say the cold is here to stay because the same trend of blocking to our N/NW/NE and the low pressure systems in the atlantic tracking S of the UK is constantly appearing in the models despite the varying output. The question is how cold? will it be dry cold? snow showers only around exposed coastal areas? or heavier, widespread snowfall via a convective NE/E,ly?

I am sticking with the colder, stronger flow from the NE/E, more widespread convective snowfall from the 12th Dec onwards.

[Model Output Discussion. 3/12/2022. How cold will it get?]

Nothing has changed my mind in the model output.

If I was going to write a forecast for the next few weeks then I would say "becoming progressively colder with increasing risk of snowfalls especially as a bitter E,ly develops from around the 12th Dec onwards"

Just add I wish Tamara would post on here. I was very harsh towards her posts and fully admit I was wrong and shouldn't of behaved so badly.

[Model Output Discussion - moving into Winter]

A couple of things I wish to say this morning,

Firstly The scenario of a more notable, prolonged, snowy spell is possible from around the 12th Dec onwards. This occuring due to blocking extending further S and alternating between Greenland/Iceland/Scandiavia. This would bring alternating N,ly/NE,lys/E,lys. Prior to this and next week is looking just cold, frosty and maybe chance of snow showers in exposed locations increasing as the week progresses and maybe even more organised showers moving inland.

I shall add that for the first time ever my opinions are not based on any cold bias as they normally are. That is because whilst I enjoy my lovely convective E,lys, I can also see the problems cold spells could cause this winter. A winter like 1947, 62-3, or even Dec 2010 would be a disaster for this country!

[Model Output Discussion - moving into Winter]

1 minute ago, Bats32 said:

Need to see what the 6z and next ECM are saying now. Now convinced by this morning's output

Im not convinced of anything at the moment apart from blocking over Greenland is likely to dominate. However I could spend an entire morning typing out the range of possibilities. Will we see very cold convective NE,lys as the GH block extends further S? , low pressure approaching from the SW but being forced back SE? , GH block less influencial allowing low pressure to extend NE from the SW bringing milder temps? , Will we instead see none of these and instead be sat under stagnant cold air?

At the moment I would say next week is more likely to be cold, frosty away from E coasts, have to wait until following week for the snowfall!

[Model Output Discussion - moving into Winter]

The Bullseye over Greenland is all I really need to say today.

I do confess to having mixed feelings though due to knowing the effects this may have on energy bills. Also increasing demand could result in rationing of supplies. The worrying truth is the infamous Greenland blocking set up can be locked in for a very long time. This is especially true if blocking remains and extends into Scandinavia and you end up with alternating spells of E,lys/NE,lys/N,lys.

Let me put it this way. If I was to draw my own synoptic charts for the perfect cold spell in the UK then it would be very close to what the ECM OP/Mean is actually showing. The models will struggle though as they always do when we see the reverse of our normal weather patterns.