Model Output Discussion - 15th March onwards

[summer blizzard]

Will perform actual analysis tomorrow but while the models have weakened the retrogressive signal, they have now moved the upper low close enough that the Euro and GFS do have proper rainfall forecast at day 10.

Not sure it's progress of something that will flip around.

[AltonMatthew]

Struggling to make heads or tails for the first time on the forum

 Retrogression being thrown around alot.

seems very technical at the moment whereas usually posts are well explained for all to understand.

 

What is currently being signalled beyond day 10 and does it really matter at this stage. 

[summer blizzard]

1 minute ago, AltonMatthew said:

Struggling to make heads or tails for the first time on the forum

 Retrogression being thrown around alot.

seems very technical at the moment whereas usually posts are well explained for all to understand.

 

What is currently being signalled beyond day 10 and does it really matter at this stage. 

Modelling has a sub 50% chance of verification beyond about a week. What we are looking for here are broad trends. 

Until tonight the trend was to pull the high west (retrogress) however this now seems in jeopardy with the Euro and GFS attacking from the south instead. 

[AWD]

5 minutes ago, AltonMatthew said:

Struggling to make heads or tails for the first time on the forum

 Retrogression being thrown around alot.

seems very technical at the moment whereas usually posts are well explained for all to understand.

 

What is currently being signalled beyond day 10 and does it really matter at this stage. 

Keep it simple and sweet.

Essentially the next 10 - 12 days are a continuation of what we currently have.  Plentiful sunshine, some cloudier periods, east coast prone to a breeze and fresher conditions, warm and pleasant in the west.  Never that hot but warm and pleasant enough for now.

Beyond that, it’s massive uncertainty as you would expect at such a range.  Possibly becoming less settled but too far out for anything other than educated guesses.  Just enjoy the early summer weather over the next week or two and worry about mid June from next weekend onwards.

Unfortunately from a personal perspective, little if anything in the way of heat and storms so far.  

Edited May 29, 2023 by AWD

[andreas]

11 minutes ago, AltonMatthew said:

Struggling to make heads or tails for the first time on the forum

 Retrogression being thrown around alot.

seems very technical at the moment whereas usually posts are well explained for all to understand.

 

What is currently being signalled beyond day 10 and does it really matter at this stage. 

Well I can start as someone who is also not in any way a professional meteorologist.

High pressure generally means stable air - with little risk of rain at its centre. Winds go clockwise around a high pressure cell 'anticyclone'.

So if we have a high pressure centred to the north of the UK and Ireland, it will potentially be feeding quite cool air down towards us from near the Arctic regions.

The 'retrogression' is a movement against the typical flow of the atmosphere in our part of the globe - so it would move the centre of the high pressure towards the west.

If this came to pass it would increase the likelihood of allowing a colder airstream with more of a northerly component to affect the UK and Ireland.

That's my understanding, anyhow.

 

 

Edited May 29, 2023 by andreas
Omitting irrelevant detail

[Cheshire Freeze]

11 hours ago, damianslaw said:

Welcome thoughts on drivers that will shift the pattern, to see a high pressure preety much sat in same position for 3 weeks is quite unusual even at the point in the year when the atlantic is very quiet.

It seems to be what we get when we're around ENSO neutral following a Nina. 2018 had a similar set up.

We seem to be in the doldrums a lot recently with the ENSO state. Probably no coincidence as to why we're seeing weather patterns get stuck for so long.

Edited May 29, 2023 by CreweCold

[Allseasons-Si]

1 hour ago, northwestsnow said:

EC goes slack by day 10 but warm too.

Potentially thundery?

Music to my ears and the eps is also stunning with a trough SW of the UK

this Scandi trough is loosing momentum as we count down the NWP clock

the retrogression of the high west seems to be on the ropes but still some ironing out yet

get the high further east and we could be looking at a warm thundery setup,....one hopes

[minus10]

18 hours ago, Cambrian said:

I rarely do more than one post a day these times, the pattern is all so very slow. Other “all year rounders” and great contributors are understandably quieter too. @minus10, @RainAllNight, @Frosty.  all good mates on here, I hope that you’re all well. 

There’s been some discussion about what might force a change from the current pattern, @damianslaw to the fore. Thank you too to @Mike Poole, @mushymanrob and @Methuselah, great company as ever, and others too, your posts keep me going with this fascinating hobby.

I can’t profess to fully understanding the MJO and Pacific forcing, @Kirkcaldy Weather mentioned yesterday about an uptick in the offing there. Over the last few days, there’s been a picking up of the Pacific jet stream persistently shown in the ops, now at day 5 on the 6z GFS, compared with the chart for this afternoon (left), while the northern arm of the Atlantic jet stream eases considerably, same on the 0z ECM op for day 6 - 

  

revving up over Japan and re-intensifying to over 280km/hr south of the Aleutian chain by day 8, then buckling before extending to the Alaskan / Canadian Pacific coast by day 10, ECM op and control.

 

Different orientation between models and from run to run, but the Pacific intensification is a consistent theme. 

How this pulse and subsequent pulses of Pacific energy interact with the Rockies and the Canadian block will be an important factor in setting the stage for the second half of June. 

It might eventually introduce a more pronounced meridional pattern in the northern arm of the jet stream, like here at day 12 on the ECM control, coincident with the arrival of the trough over the UK and Ireland that we’ve been seeing on the means, the emergence of a more pronounced 5-wave hemispheric pattern and something with potential for being a tad less static.

  

I see that the 6z GFS op drops the upper trough further west over the Atlantic at day 12, in keeping with @Tamara’s ideas of a warmer heights from the south pepping up the convection (great photos) ahead of the low slowly encroaching from the southwest. Same point though, another much more decidedly meridional setup and a 5-wave pattern, this one placing us more kindly in a warm ridge. 

Well, I’m off out to enjoy another afternoon of this vitamin D inducing borefest , because the lengthy dry pattern will in time change, at least for a while, and I’ll have to retrieve my coat from underneath that pile of lazily discarded sun hats. 

Thanks @Cambrian, Yes i,m okay...just that domestic stuff and work take over your life at times...still keep a watching brief though..interesting this morning looking at the gfes 0z how much above average 850 temps are being forecast despite the fresh feel to the weather down here...

..gfs looking to bring in a south easterly for second week of June ..warming up and as others have said potential for thundery activity...

...in the meantime dry is the theme...actually amazing how quick the ground is drying out here...particularly the top part..still...i am going to refrain from saying we will soon be needing rain ..

..although fresh and bit chilly in the wind here particularly when cloudy it is great conditions for outdoor work..when the sun shines the blossom looks lovely....

..best i have seen it for many years ... looking forward to a potential warm up and maybe some thundery showers..retrogressing high permitting..

 

[sheikhy]

Fantastic ecm this morning!!!warm bone dry all the way to the end!!!unsettled weather keeps gettin pushed back!!gfs very nice aswell!!little blip for bout 24 hours between 216 and 240 hours but then high ridges back in after!!!ukmo bone dry to the end aswell!!

[Cambrian]

I can honestly declare that my awkwardly overheard comment to the effect that it’s all looking a bit wobbly this morning, which gained a poor reception locally here, was actually aimed at our incumbent high pressure.

The ECM extended range weather regimes chart from yesterday picks up on this nicely, the Atlantic ridge signal for 2 June, corresponding to a moving west of the core heights in the Atlantic to the southwest of Iceland here on the 0z GFS mean anomaly, before being edged out by a renewed blocking signal by 5 June, fitting in with it wobbling back east and extending heights further east over southern Scandinavia and down through Central Europe. 

   

By day 10 (above right) it wobbles west again (no use of the R-word in this post!), withdrawing the heights from Central Europe and refreshing the strong Atlantic ridge signal, but still looking good for the UK and Ireland. 

As alluded to above - great to see your post, @minus10, it looks like there is gaining momentum for a change around the middle of June, with a loss of both the ridging and blocking signals and a modest uptick in the NAO+ signal. The 0z GFS mean is picking up on this too, at the end of the 0z run, with lower heights edging up from the south, reflected too in the ECM weekly mean anomaly charts for week 3, 12-19 June, for heights and pressure. 

  

Looking to be less settled for just a few days at the moment though with the blocking signal returning strongly by the summer solstice. 

The weather here this morning is absolutely lovely again - not the slightest bit wobbly actually. Strangely brighter indoors too. I must stop talking out loud as I write. Have a great day. 

[Mike Poole]

38 minutes ago, Cambrian said:

By day 10 (above right) it wobbles west again (no use of the R-word in this post!), withdrawing the heights from Central Europe and refreshing the strong Atlantic ridge signal, but still looking good for the UK and Ireland. 

That is currently the suggestions from the models in the post-10 day range.  However, given their recent performance in overblowing this scenario, given the thoughts on here of @Tamara  and @MattH, and given what the seasonal models were predicting for June last month, you would have to question the marked part of the regimes plot from the ECM 46:

Is this a phantom signal again, would be my question? 

[Downburst]

Very little blues (+NAO) on those 46 day regime charts. That's looking good to me for June not matter what I'll take a Block or Atlantic ridge being in Ireland. Looking at the rain and temp anomalies I am hoping Spain and Portugal have good reservoirs to catch the rain this June. 

Also of note is there is a strong signal for the very end of the run, which is interesting into July for may be more of the same

But quickly back to next week and rainfall anomaly Europe

[ANYWEATHER]

Ecm is going to go the way of the gfs in the ten day…….?

[lassie23]

When is it going to rain

[mb018538]

These persistent low pressure and associated rainfall anomalies across southern Europe are really exceptional. Yet more serious flooding issues on the horizon over the next couple of weeks.

[pad199207]

1 minute ago, mb018538 said:

These persistent low pressure and associated rainfall anomalies across southern Europe are really exceptional. Yet more serious flooding issues on the horizon over the next couple of weeks.

Is this the new summer norm now?

[Tamara]

13 hours ago, Allseasons-si said:

Music to my ears and the eps is also stunning with a trough SW of the UK

this Scandi trough is loosing momentum as we count down the NWP clock

the retrogression of the high west seems to be on the ropes but still some ironing out yet

get the high further east and we could be looking at a warm thundery setup,....one hopes

it is academic to say that taking one operational output from one model is never a sensible way of gauging the numerical output outlook but taking the GFS 06z output this morning at face value is actually, for what it is worth, a guide as the type of evolution that has been under the microscope recently. The upstream retrograde signal being something of a red herring distraction from this, and as discussed in detail over the last week/10 days would be jumped on by the models and then quite conceivably backtrack upon.

The Iberian instability continues apace down here is SW Europe. There is an element of insanity to this video. Do not attempt what these people in the Ourense region of Spain did yesterday!

Video da ponte romana de #Ourense anegada no medio dunha fortísima...

FB.WATCH

---

3.7 万次观看、 146 次赞、 19 条评论、 340 次分享，Redmeteo 的 Facebook Reels: Video da ponte romana de #Ourense anegada no medio dunha fortísima treboada esta tarde. Descoñezo o autor, envíanmo por Instagram....

 

Edited May 30, 2023 by Tamara
Edited. in Spain !

[Cambrian]

Yes, there’s clearly a high degree of marginality too in what the regimes’ algorithm designates as an Atlantic ridge or a blocking signal. Comparing with the previous forecast from last Thursday, it’s modified a 3-day chunk from the middle of the 11-day stretch indicated in the last forecast for the start of June, in favour of a quick little peak in the blocking signal. Thursday / Monday 

 

I’m guessing that the algorithm is essentially working off the difference in heights between the Atlantic and European zones. In this setup, it seems to be very dependent on how far into Central Europe the peripheral heights extend from the Atlantic, and very sensitive to changes of just a couple of hundred miles at the southeastern edge. 

It clearly is primarily an Atlantic high, albeit oscillating, in the first instance, supported by the bolstered Atlantic ridge signal over the next few days, during 1-3 June, 0z EPS day 4, though with the surface high extending southeastwards beneath the core heights to take in Ireland and the UK. And it’s an extensive block, peripheral heights stretching from Newfoundland to Austria. The 0z ECM mean anomaly animation for the next 10 days neatly shows the wobbling of the core heights of the high west to east then west again. 

  

To be fair to the question as to whether it actually does move back that far west in reality despite the cross-model agreement (GEM mean onboard now too (day 10 mean anomaly above) along with GFS means posted earlier) it is fair to point out that this continues to ghost us as a day 10 signal more reserved to the means. Added to this, heights through Central Europe have proven more resilient than forecast at week 2 time and time again, so I share the reservations. The 6z GFS op migrates the high to Scandinavia, with a meaty looking upper trough having dug out the Atlantic high as early as day 8.

 

The loss of ridge / blocking signals from around 8 June and the subsequent drift to no overall signal consistently being shown on the regimes does suggest that the heights do eventually relax enough to allow some lower heights and shallow low pressure to influence particularly Western Europe, but this is a slow change, the 6z GFS op eventually having done the deal by day 12 with low pressure for UK and Ireland, and until then at least, it looks like we continue what is becoming a notably dry spell.

[alexisj9]

27 minutes ago, pad199207 said:

Is this the new summer norm now?

Looks like either this or a heatwave in the summer now for main land Europe. It's unfortunate about the flooding, if it wasn't for the fact they are getting too much rain, they would probably be relieved it's not the same as last year. We thought we were hot, they had it much worse.

[northwestsnow]

Is it too early to be thinking about winter ?

00z runs leep the settled theme - hoping after another 7 to 10 days of dry conditions we might see some storms ..

[In Absence of True Seasons]

46 minutes ago, pad199207 said:

Is this the new summer norm now?

No, why would it be? It's an anomaly for all intents and purposes. I've been to Spain, North Italy, other places in central Europe in May / early June before and it the climate is reliably warm and sunny, with the odd light shower here and there at most.

[damianslaw]

Any other examples of a 3 week period plus with core heights of a high sat just to the south of Iceland. Feels the atmosphere is stuck on pause at present, barely anything moving. Its quite an abnormal set up, why is the set up so slow moving.

Edited May 30, 2023 by damianslaw

[Sunsetglimmer]

Roll on the Atlantic or a warm southerly this north east wind direction can buzz off now 

[MattH]

3 hours ago, Mike Poole said:

That is currently the suggestions from the models in the post-10 day range.  However, given their recent performance in overblowing this scenario, given the thoughts on here of @Tamara  and @MattH, and given what the seasonal models were predicting for June last month, you would have to question the marked part of the regimes plot from the ECM 46:

Is this a phantom signal again, would be my question? 

The Atlantic ridge signal could be related to the expected spike in the PNA pattern looking ahead, which is set to become quite significant, this all links in with an Aluetian low pattern, W USA Ridge, E USA trough and downstream of that an Atlantic ridge, this links into the period when the UK may well then see more of a trough pattern as we approach the mid-June period. Clearly, there is still some evidence for a -ve NAO as well. To what extent any troughed pattern becomes established is the key uncertainty and for how long, but the evidence is clearly stacked now towards another significant rise in AAM, from a "low" point of approx +0.5sd currently, we are already seeing a jet extension pattern modelled as well (see below GEFS example). This is highlighted well by the overnight EC46 and how the trend is, in particular, as June progresses, while the VP200 anom pattern is also indicative of a Pacific that will see further -ve VP200 anomalies, without any active MJO event.

In terms of the next significant MJO event, then the consistent signal here is for a likely event through the end of June and into early July, not before. We can see this consistently within the CFSv2 plot (highlighted by the solid red lines) and also the ever-useful and reliable EWP plot as well. It will be very interesting to keep tabs on this event as it would be arriving during the mid-summer period and could well have some significant 'say' as to how the patterns evolve through July and also August as well. From what I envisage, it could push the UK into a very warm or hot summer pattern during the second half of July, but all are very open for discussion at that time frame.

Also as has been discussed for some time, the current anticyclonic signal was discovered back in mid-April, the recent fall in AAM and +ve PNA trend does support a pattern where the current NW European high ends up more to the W or NW, with a troughed pattern over the British Isles, leading to a more convective interval, but not a 'full blown' cyclonic period, and with then support for another AAM spike as June progresses, allowing for a reset of the pattern, but with the risk that unlike currently, the main CoG of the high is more over or to the east of the British Isles, with a trough to the W or SW. Could that then become the primary default pattern for much of the summer period (?) time will tell, as I do think there is still scope as well for northern blocking at times this summer, not necessarily just a European high, but one long-term event that will need watching is the amplitude and influence of this MJO event that should arrive later June and into July.

Cheers, Matt.

[Guest]

GFS hinting a change mid next week as things turn more southerly, initially warmer with mid-high 20s possible and something akin to a thundery breakdown in time for the following weekend.