Model discussion highlights

[Kirkcaldy Weather]

 

 

 

Super happy with the evolution since Late December now its becoming clearer in some finer detailing of this upcoming significant cold episode.

• Significant cold front moving south bringing significant below avg surface and 850hpa temperature anomalies by Sunday January 14th
• Surface temperatures point to a severe winter weather event.

"Through Jan week 2 toward the aforementioned middle month period we'll have the -NAO,-AO,PNA,El Ninò,MJO and Easterly QBO feeding towards the setup going retrogressive this will have a couple of significant changes with a westwards moving trough which links with expectations into elongation with the centre over the Baltics, Scandinavia as this is occuring the high pressure and block will shift northwestward to reside across Greenland this is more supporting of colder 850hpa temps likely from the Northeast, we maintain below average surface temps during this with possible scope for these to get colder"

'Seeing the heart of these colder temperatures at surface and upper level becoming centred through Europe with just the far south of the UK clinging to is perfectly anticipated thanks to the phase 7 feedback'

Note the movement northwards of this cold anomaly from phases 7 into 8

From the above we can Note the significance of both 850hpa temps and in particular surface temperatures as both will contain anomalies roughly 15 > 20 Degrees BELOW AVERAGE, this will give multiple ice days in succession with liklihood of significant ice days over Scotland and Northern regions of England though there will be ice days for Ireland  

A timeframe with a focal point towards wintry precip event(s) will be from January 16th through 18th with the cyclone in the Atlantic starting the merging process to the Scandinavian Baltic Trough

7 day precip anomaly. I'm expectant of significant flash flood event[s] for Portugal and its border into Northwest Spain

Such an excellent showcase of all the teleconnective feedback coming into one stunning meteorological display

"My thinking holds steady with the MJO working into the Maritimes generally Mid Jan maybe into January week 3 as this increases cyclonic developments seeing these sorts of 500hpa setups during that period is very plausible.''

 

Following the MJO passing across the Maritimes we begin seeing feedback of phases 1 and into 2 as January week 4 gets started a high forms toward the Maritimes which might extend through Canada, also I'm starting to notice the trend toward cut off low development toward Mexico, far Southwest US  

 

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007007

[phil nw.]

Forgive me for the number of images in this post but i thought i would try to give my views on the coming 10 days or so.It's just an overall picture so no micro details just how it looks like the pattern might change-- with supporting data.

To begin i think we can say with some certainty the cold will deepen from Sunday as the Arctic air arrives from the north.We will have to keep an eye on the small low development around Iceland shown around day 4 and how that interacts with the general cold flow across us by then.But after all said and done modeling shows the cold gets to the south coast by Monday.

The other main point is the probable Atlantic approach later next week modeled on the UK T144hrs model.

Just to show that this is very much still on the table but as already been said nothing is certain at that range but to give an idea. of what is likely to come.

Now looking at the combined 850hPa ensemble graph

Cold this coming week but no denying there appears to be a trend upwards beyond .

This, shall i say less cold period, has been spoken about as the mjo enters a warmer phase before forecasted to move into a more favourable area for a return to blocking later.

Looking above at the Stratosphere the spv is currently expected to split into 2 centres up to mid-level in the coming few days before reforming in week 2.We can see these 2 centres over Siberia and Canada ,which enables the current Greenland area ridging of heights

These from gfs latest and yesterdays ecm both showing the same trend.

 

 

As can be seen the gfs images are a top to bottom profile and show what Amy Butler called the pair of trousers on the split image.The Ecm image is for 100hPa level,.Both sets do show the vortex reforming which seem to imprint down to our level.This would support the upwards trend in temperatures with a probably return of the westerlies at least for a short while.

The change towards showing on the day 10 ensemble 500hPa mean anomalies.

The pattern moving north as heights over the pole start to drain away.

So the hope is that in the next week or so we will see some snow either from minor disturbances or a battleground event from the south west which may become the main feature as it fights it's way up the country as a mild pattern tries to take over.The uncertainty is how far north this will establish and of course for how long.

Plenty of interest going forward i reckon. 

 

 

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5006980

[Tamara]

18 minutes ago, Cold Winter Night said:

Thank you for your very insightful posts as always.
I can imagine it must be refreshing for you for once not to be forced by the diagnostic to go against the cold preference in here...

What I do wonder about is why apparently the NWP in the extended is so rudderless, as it seems to generally ignore that retention and renewed push of +AAM. With your explanation of the wind flow budget in mind I would expect a very large spread later on, but this morning's EPS had only a handful of members that retain heights in more Northerly latitudes, the ensemble even seems to converge on that +NAO outcome that is the polar opposite (quite literally) of a +AAM response. EPS even more so than GEFS, I must say.

Considering all this, it seems like we might have to brace ourselves for some model output surprises over the coming week. A highly interesting battle between GSDM and NWP.

Based on the modelling of the huge gyre of vortex across NE Europe and that part of the arctic to retrograde in tandem with the Greenland amplification it makes sense that height anomalies will respond accordingly to a more cyclonic regime. But is is within that regime with embedded upper and increasing surface cold across N/NW Europe and remaining pockets of -ve zonal mean -ve zonal winds at high latitudes that considerable resistance must surely make it difficult for flat westerly inertia to cleanly navigate the road blocks. Additionally, it will not be long before a further push comes from momentum transport from the tropics into the extra tropics to replenish the sub tropical jet stream and equally further poleward amplification. Putting that together, disruption of vorticity is more intuitive to expect than positively tilted wholesale displacement of -ve higher latitude inertia & its associated dense cold air.

NWP is not ignoring the tropospheric diagnostic and not battling it. NWP doesn't lead the diagnostic. It is rather led by it, but trying to decode a lot of complex factors that do not align with the traditional westerly gyre of a +ve AO and NAO. 

Lastly and finally on this, the term "rudderless" refers much more to collective smoothed ensemble means. It is of course possible to look at individual clusters of ensemble solutions to see which are maybe in the ascendancy or vice versa. But even here, if the overall modelling is blindsided by a false signal or jet stream bias calculation at a given distance, then members within the clusters will also reflect that inaccuracy. They are best looked at as a snapshot in time of progress (or otherwise!), and not any definitive prediction at that given distance.

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007043

[steveinsussex]

3 minutes ago, MATTWOLVES 3 said:

Its officially Mattwolves day  @AdrianHull the met do indeed signal a milder push by next weekend

But there's scope for significant falls of snow during the run up to it! And as always and like Tams points put there's alot going on and this may only be a minor blip with drivers looking good again later this month.

To sum up I reckon lots of exciting times in the days ahead.

Now let me just buy my informant a beer

The 19th was when we were looking at the low pushing into the south wasnt it? thats next friday, thats "by next weekend".... so would suggest its likely to be rain?

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007070

[Catacol]

Do my eyes - and my refresh button - deceive me? Has the MetO just put out an updated medium forecast for next week and then retracted it back to yesterday's within an hour? Hmm. Maybe my computer is broke. I'm off for an MRI shortly - my knee is definitely broke unfortunately...

Meanwhile if you do nothing else today please read Tamara's surfing post and avoid being a slave to NWP output in the unusual pattern that is beginning to unfold. NWP doesn't deal with blocking patterns very well and tends to default too quickly to default westerlies when the blocks get hard to read. That's not to say that week 2 isnt going to get less cold - I think it looks likely that it will - but such phrases are relative and folk should keep in mind that Glosea Feb forecast from yesterday.

I just had a team meeting and we discussed the potential impact of snowfall next week. First time I've done that since 2018. Gave me a warm, fuzzy feeling. What is it about snow that is so alluring? 

Best post a chart to keep the ModPolice happy. @Scott Inghamday as start of the proper cold feed now looks a nailed on certainty. Scott - early creme eggs are yours....

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007037

[MATTWOLVES 3]

It's a strange Winter this year as even Doc Amy is a bit stumped..PV acting very odd this time around..wouldn't at all be suprised to see it fall before we are done.

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007128

[Tamara]

4 minutes ago, Mike Poole said:

850s, nice, we can live with that!  Puts us in a great place for the chaos when the block does fail.

Two things:

The energy distribution on UKMO is much more separated upstream than GFS and hence tendency towards a more split flow/ sub tropical jet is emphasised.

Also the -ve inertia (-ve zonal wind pockets) at higher latitudes is modelled much more and the amplification inertia within the extra tropics has less low AAM bias than GFS - which piles all into the polar jet and ends up with the scribble in the extended period that it does. It sees a brick wall but models/simulates attempting to drive straight through it anyway.

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007273

[nick sussex]

Just now, Drifter said:

‘Scribble’ - great description for what GFS churned out in FI. 

I think I’d call it dog vomit ! 

 

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007290

[Tamara]

45 minutes ago, Bricriu said:

Well I hope she is right, but the form horse looks a return to milder weather.  What we don't want is a tepid return to milder  weather, either let's at least have a massive snow dump from a frontal  event or a good unstable northerly airflow,  but I am not confident  of either happening now. If this is the case then it's a big anticlimax after what seems  like one of the longest chases ever 

Without going to into all the huge detail and nuances all over again (there isn't the time with other things to think about anyway) its worth reading exactly what is being suggested again.  Not just by me but various others as well Bear in mind my own purpose is not to chase any particular weather type, but try to evaluate what is most likely to happen as to best of ability. And I do have a Portuguese head on at the same time.

The analysis also bridges heading towards and into February and does not rule out, as said earlier, milder incursions for NW Europe. However, in the round, the emphasis especially earlier and then again a little later is probability weighted for cold blocked conditions to be predominate. This too, discussed in detail how and why previously.

Also suggested was not to be reactive to each and every NWP suite and form instant conclusions - but evaluate them from day to day. One corner at a time.

A very nice evening to everyone

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007593

[Rain All Night]

8 hours ago, RainAllNight said:

A summary of this morning's runs.

Deterministic runs (to day 7, Thu 18th)

T850s for Dorset (to day 8, Fri 19th)

The second mild bump seems to have been blunted since last night.

ECM

UKMO

GFS 0z & 6z

Ensemble means (day 10, Sun 21st)

It still looks as though a reset is coming, unfortunately...

An overview of this afternoon's model outputs.

Deterministic runs (to day 7, Thu 18th)

T850s for Dorset (to day 8, Fri 19th)

UKMO, GFS, ECM (plus an ECM meteogram to highlight the day, Wednesday, when a warm front may be paying us a visit down here, which is the green bump on the grids; interestingly, the chances of this bringing rain seem to be higher than the chances of it bringing warmer surface temperatures)

Ensemble means (at day 10, Sun 21st)

It's OK, Tamara won't let this happen to us 

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007617

[bluearmy]

10 minutes ago, nick sussex said:

Indiana Jones And The Mystery Of The Disappearing Shortwave !

Very bizarre turn of events . 

This must be the first op run for days without that shortwave . 

It’s just a weak wave of fronts in the flow rather than a distinct system west of Ireland.  As a result the flow is further south and 850’s 2c-3c lower 

we also see the push of slightly less cold 850’s moving west to east T108-T120 into the North Sea 

the lack of the distinct shortwave on this run reveals that what’s left is still very complex within the broad cold trough

 

 

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007745

[Scott Ingham]

The wedge isn’t probably prominent enough on this run but if you look where the black arrow is pointing you can see where the residual elements of inertia have created a wedge. Run it back and forward and you’ll see the trough west of Greenland breaking up and sliding. 
 

This is what could potentially extend our spell. I’d like to see the ensembles move over the next 3 days then it’s game on!

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007854

[Captain Shortwave]

Some very strange goings on around day 4 in the ensembles. The cause of this appears to be a shortwave appearing on the core low heights over Scandinavia that passes fairly close to the east coast of Scotland, this appears to enhance the depth of cold sweeping down the eastern side of the country.

Just posting one ensemble to show this;

Note the kink east of Scotland on here.

So lets see if any other models showed this;

ECM

It is sort of there to the north of Scotland, but it gets more absorbed into the part low. It might be worth keeping an eye on because a shallow system with embedded frigid air appears and heading close to the UK could be the surprise we were hoping for.

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007944

[Ice Day]

So, ice days are possible for many for the whole of next week 

    

Feeling absolutely Baltic in the north.

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007900

[nick sussex]

The GFS the most progressive solution .

The ECM makes changes upstream but still pushes too much energy eastwards .

Still time for that to change with more energy heading se .

The GFS is an outlier solution in the ne Pacific as it allows a ridge to move sw earlier than the others which helps to eject the Canadian troughing earlier and without any hang back so the whole thing barrels eastwards .

 

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008188

[Kasim Awan]

6 minutes ago, geordiekev said:

Way too early to be discussing snow chances still, until a consensus is within the reliable. Hence, not too worried about interun variables just yet, as long as the macro pattern still looks peachy, I'm happy

We could end up very lucky or very unlucky depending on the positioning of lows. There is the potential here for a widespread, heavy snow event given the instability around and placement of cold air. However, on some of the runs shown this morning most of the troughs which develop miss the mainland so equally the potential is there for a dry cold spell. So there is no guarantee that "troughs will pop up everywhere in the flow", this is not quite correct, as we need optimal synoptics for troughs to develop. The GEFS does bring that low mid next week significantly further North, so a big snow event from that is still on the cards. Other chances come from the low moving south east Monday into Tuesday and early signs suggesting a trough could develop to the West of Ireland later next week. These are our main chances next week.

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008099

[Mike Poole]

ECM clusters - just one cluster until T168, which is the timeframe that is really of interest, so once again there is little they can tell us, but T192-T240 does show something interesting:

Which is that cluster 1 does retain/rebuild the ridge!  And maintain lobe separation.  This, IMHO, is the direction we should be looking in.  Cluster 2 contains the op and is more mobile for a time, and cluster 3 is the more southerly tracking jet option.

 

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008234

[northwestsnow]

MOGREPS says what breakdown

Sorry thats Leeds 

London looks v good too

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008233

[Mike Poole]

ECM extended clusters T264+:

If we recall in the previous timeframe the majority cluster 1 rebuilt the ridge - to do this it needed some WAA into Greenland, and this came from developing a powerful system on the ESB.  Not really focusing on details here, because lots of runs in this have probably got the early evolution wrong, but the trend here seems to be for that system to move east, and push up a ridge ahead of it, you can see on clusters 1,2,3,4 - but you can now see how this could end up as a Scandi high, cluster 4 the closest.  If the earlier cluster 1 was right, one might expect this signal in the extended to get stronger.

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008275

[Singularity]

The ultimate level for week 2 forecasting is correctly anticipating the impacts of model bias, which can strongly skew entire ensemble suites.

Alas, that’s a lot easier said than done!

I sure can see how GFS & ECM might be incorrectly presuming a more traditional route for the westerlies associated with the initial stages of rising AAM (a.k.a. lagged impacts of AAM having recently fallen to near neutral). In short, if enough residual heights hold on at the high latitudes via lingering easterly momentum anomalies, the strengthening polar jet will be redirected into S Europe instead of N.

It is inevitably an ‘if’ but the point is, it has more chance of happening than the ensemble products currently suggest.

In other words, best keep an open mind as to what may happen even on the broad scale later next week & through the one after.

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008298

[Ice Day]

Incremental improvements on the GES mean out to 126 vs the 0z. Nothing major, but it's moving towards the UKMO (and Icon?) solution, bit by bit.

 

  

  That's far enough out for me now, the uncertainty kicks in around this point (a bit before actually).  Adios until the 12z's 

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008467

[Battleground Snow]

1 minute ago, Mcconnor8 said:

I think it would end up *something* like P34 on the ECM 0z run, ridging back into Greenland with the cold hanging on into Tuesday/Wednesday next week instead.

I think the output is sniffing the scandi heights maybe a couple of days too early, with mjo only getting into phase 6 around the 20th.

With the lag a more realistic timeframe is probably around the 27th/28th @Scott Ingham

If we can keep the pattern cold with wedges until then, that would be a bonus

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008453

[BremX]

Oh it's amazing how the "I told you so" brigade come out. 

Even if things revert to mild and the potential colder weather doesn't materialise, there are no kudos to be given to people like that. We know the normal set up for this country, it takes a lot of things in place to get the sort of weather that most on here are chasing. 

A lot of people with a lot more knowledge than I have looked at so many different factors and shown that there is a possibility that it could line up right for cold and wintery weather. 

If it doesn't happen it's not their fault, it's just something else has overridden the other signals.

Looking at the charts today, personally I would say, given how much the models have flipped over the last week alone, by this time tomorrow, things could look totally different again. 

GFS is always wanting to revert back to type, to overdo low pressure systems and basically mug us off. 

ECM, while perhaps more steady, can be just as wrong.

Other models can show us nice charts, or bad charts depending on which ones we pick. 

There is still a lot more runs to go, the cold is deepening on this initial northerly, which, whilst probably dry for most, is still winter weather. 

Let's get the cold in and see what the models make of it after that. 

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008227

[Cambrian]

0z EPS for days 7, 8 and 9. In broad terms, day 7 shows the battleground setup, with a northwesterly upper flow, sending cold air into the UK and Ireland. Day 8 shows the flow turn more westerly with low heights in the mid Atlantic, looking like the Atlantic has broken through. But by day 9, the gap is reinstated, with mid Atlantic heights pointing up to Greenland.

  

Compare this with the day 10 chart from yesterday. Markedly less of a mid-Atlantic gap, much less amplification yesterday, replaced now at day 9 by the beginnings of a good looking ridge up to southern Greenland pumped up by cleaner core low heights to the west of Newfoundland, the low getting hindered in its attempt to move east out of North America. Yesterday’s day 10 / today’s day 9.

 

The models are struggling big time. The Scandinavian trough is still very much in attendance and looking at that, a reasonable observation would be that it only needs just a little more amplification in the Atlantic heights to altogether prevent any phasing of the troughs associated with two lobes of the PV and keep us very much under the influence of the cold trough to the northeast. 

Next few days model watching for me reminds me of getting on the train - when the guy over the tannoy says - watch the gap!

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008372

[Derecho]

A huge increase in the uncertainty of the EC ensembles in the space of 24 hours between T96 and T120.

I suspect we could see some dramatic swings in the model output through the weekend with things becoming substantially clearer by Sunday evening for later next week.

GFS is even more uncertain during this time period. Usually by T72 the spread reduces markedly.

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5008486