Model Output Discussion - Spring Has Sprung

[Neilsouth]

 Summer8906 Unbelievable that it looks dry in the models for the next few days, and then it changes and we are back to more rain! It was supposed to be dry tomorrow up to friday. Now looking like drizzle and showers. Wont feel mild under that lot.

Any sign of a weeks worth of dry weather from GFS? UKMO? probably not

[Mcconnor8]

 Neilsouth Nope, a low pressure fest on both of them for the next 7-10 days unfortunately, I'm off to Mallorca for a few days at the weekend to get some needed sun and thankfully looks like it will tap into some Southern Europe warmth while I'm there which is a bonus. Still doesn't really look like any impact from the SSW in the modelling at the moment either.

[Cloud 10]

The SSW forecast to go on for a fair old while,but struggling to make it down past 100hpa.

 

[danm]

 

[KTtom]

Hoping ECM have more luck with their day 10 charts in Spring than Winter..

[WYorksWeather]

 Summer8906 Only just had chance to reply to this. In short, the answer is it depends on what you mean by mild. Mild or warm in terms of feeling, probably no. But statistical mildness isn't always the same. It's well worth remembering that minima even in the south for late March are only around 4C - generally much wider diurnal ranges than in autumn. So brief sunny intervals interspersed with showers and then mild and cloudy nights often read higher for the CET than warm and sunny days with colder and clearer nights. 

And the SST anomaly near the Azores is still there, so you can probably add a degree or two onto the normal expected temperatures for south-westerlies in any case:

[WYorksWeather]

The GFS ensemble is still going for generally above average temperatures for the next week or so. There is a cooling trend beyond that, but the lack of many (or indeed any?) clear nights means that overall mean temperatures are likely to be no lower than average. Probably not even so much as a ground frost in the south for the foreseeable.

Even if you look further north there's really not much sign of much to play with in the way of cold. As always there are a few colder options in the extended range.

Probably the best chance for any drier conditions will revolve around some of the more amplified Azores high options on the table. Either of the GFS or ECM operational runs at day 10 are fine with me. ECM is particularly exceptional.

Unfortunately the day 10 means are a little more equivocal - GFS especially seems to struggle to get the high far enough north for anything more than an occasional drier interlude. ECM still isn't bad though.

[Addicks Fan 1981]

 Cloud 10 we might not have a final warming now and for the stratosphere to be around the temperatures at 10 hpa to be around with what they should be like.     

[WYorksWeather]

Good to see the GFS 18z also playing along with the 'slap a great big high over the UK' scenario at day 10.

Frankly the orientation of the high doesn't even matter that much, at this stage we're absolutely crying out for a sustained dry spell. As it happens this one has a bit of something for everyone. At day 9 we get a brief northerly toppler:

Then by day 11 it looks mild:

Also great to see this on the chart from day 9 to day 11-12 ish. The block is strong. Finally, it says to one of those Atlantic lows: GET IN THE SEA!

Let's hope we see more of this, and we can count this down from the semi-reliable to the reliable.

[Derecho]

On 11/03/2024 at 20:54, feb1991blizzard said:

Some reversal this - but we could have done with it flatlining for a bit longer.

Will it equate to cold though? I think we'd have to go down the Greenland High route for that, April 2021 type synoptics. It's a contrast to late March 2013 when the continent was still very cold.

I think there is too much of a focus on stratospheric winds sometimes, we can become hooked on these charts when the jigsaw pieces aren't in place for a cold spell to happen. Sure some northern blocking is a good bet... but easterly winds are common as we head into late March through to mid-june anyhow.

Does the stratosphere get more focus and attention then it deserves? It's fascinating and there is some good science behind it but it's renewed focus in recent years is likely due to the BFTE and the succession of poor winters that have preceded and followed it.

Edited March 12 by Derecho

[alexisj9]

 Derecho you don't need a SSW for a bfte, and a SSW doesn't always bring cold when it does happen.

[raz.org.rain]

 alexisj9 by the looks of things, the SSW could do quite the opposite if it does anything for our shores at all.

[Cambrian]

Things shaping up a little bit better now. Successive waves of building heights around the Azores are gaining a modicum of momentum in the models.

As I alluded to a few days ago, there’s a practice run this coming weekend, here on the 0z EPS at day 4. It’s a shallow ridge, giving just a bit of a break before the flow from the southwest resumes, but a pleasant Sunday afternoon over England in particular with temperatures up to 15 degrees on the op. 

 

What is interesting from there is that though the Atlantic trough does make very slow eastward headway to be hanging down through the UK and Ireland by day 8, it weakens considerably against the European heights.

 

This weakening of the trough means that the next wave of Azores heights is able to line up a better effort towards the weekend after next as the trough gets shunted east and squeezed out. This build looks to be getting its act together by around day 10. The 0z EPS / ECM mean shows a solid build in heights nicely oriented northeastwards in the direction of the UK and Ireland.

 

So slowly gaining Azores momentum. What we’d perhaps expect this time of year. It’s not looking like sustained dry spells by any means, more like 2-3 day spells of drier, more settled weather between slow moving troughs, but I’m alright with it, as long as we get the breaks. When it rains, I can wear a coat. 

There’s always a lot of interest in the potential for wintry weather and at the other extreme, summer heatwaves. But spring, with its better light and resurgence of nature, though often under-rated, can be a lovely time of the year. 

To make the most of it, I’ll probably be posting a good deal less, so have a good few weeks. 

Edited March 13 by Cambrian

[summer blizzard]

 Derecho Current SSW looks like it won’t downwell enough but we might see a more diluted weakness make it to the troposphere and wave activity can always enhance this. 
 

So I’d say we might get an impact but late in the month. 
 

Just in time to ruin April perhaps.

[Rain All Night]

22 hours ago, Rain All Night said:

0z deterministic runs, out to Tue 19th (day 7)

Nothing interesting in the next week, doesn't look too bad down here for the most part.

0z ensemble means, out to Wed 27th (day 15)

Azores ridge around the equinox, then maybe an Atlantic ridge towards the end of the month?

0z deterministic runs, out to Wed 20th (day 7)

A brief surface ridge over the weekend, and then some opportunities for some settled weather further south and east into next week.

0z ensemble means, out to Thu 28th (day 15)

Still seeing a convincing signal for an Azores high extension towards the UK around the equinox, followed by a less convincing but nonetheless recurring signal for a pressure rise further west that could force a chillier air flow over us late in the month.

[Mike Poole]

14 hours ago, Derecho said:

Does the stratosphere get more focus and attention then it deserves? It's fascinating and there is some good science behind it but it's renewed focus in recent years is likely due to the BFTE and the succession of poor winters that have preceded and followed it.

It is a fair question.  The evolution up to and after a SSW seems to be predictable on a much longer timeframe than other things affecting our weather in the winter.  And when that includes snow for us at some point during that evolution, everyone is interested to discuss it!

But in recent years, BFTE18 excepted, there have been interesting evolutions in the stratosphere but they have done nothing to halt the run of diabolically poor winters.  This year, the strat has been absolutely fascinating, and quite different to many recent years, and yet it has done nothing to help promote any decent cold spell here.  It is far too soon to say whether this has just been down to bad luck, or whether the bar to clear to provide the forcing necessary to get blocking in the right place is now getting so high with climate change that SSWs are going the way of favourable MJO phases - i.e. just don’t seem to deliver any more.  Time will tell…

 summer blizzard I agree.  It looks to me like there is perhaps more of a signal for some high latitude blocking in the 10-15 day range on the models in the last day or two, but it looks a bit anaemic - so the SSW probably will have an effect, but nowhere near enough now to turn the clock back to winter (for those who hanker after that!) but also, as you suggest, will still probably manage to hinder the progress of decent spring weather that most now want.  Ho hum!

 

[KTtom]

Does the stratosphere get more focus and attention then it deserves? It's fascinating and there is some good science behind it but it's renewed focus in recent years is likely due to the BFTE and the succession of poor winters that have preceded and followed it.

 

Good question with the answer probably yes! I think most, like myself struggle with teleconnections so the good old SSW = Freeze is a nice simplistic correlation. The Met give it more attention than other drivers so we the public do likewise. I would say on average its the best signal we have when things are about to change and even that seems to be backfiring this year as they have struggled to effect the troposphere in a noticeable way.

[Methuselah]

And here's this week's Met. Office Ten Day Trend: current levels of wetness could be coming to an end?

 

[Addicks Fan 1981]

 Cambrian great post as always and it does seem that the weather is having a very close tie with the MJO movements that are taking place as the MJO is very active as things stand.    

[stodge]

Evening all

MJO forecast to enter Phase 7 at high amplitude early next week and then, as per usual, start to decline as it approaches Phase 8 in 10-12 days.

Can anyone with the composites see if the current model output mirrors these composites? 

The rainfall patterns are consistent with a SW'ly flow so not good for the Lakes, North Wales or South West Scotland but much drier further south and east. 

Not much of a signal that I'm seeing tonight for a significant pattern change before Easter.

On the stratosphere, what has surprised me this winter has been the rapid recovery from near reversals or, as now, more defined reversals. That would be consistent with a colder strat which is in turn one of the signals for climate change so the question for the future will be, even if a more turbulent and active atmosphere encourages more warming events, will they be strong enough to facilitate a strong enough SSW with strong enough downwelling to promote significant tropospheric impacts?

 

[Neilsouth]

 Methuselah Considering how badly wrong they've been for sometime, I count 5 times this month alone... I'd hold back on the week aheads! ( Even the models are struggling / GFS/ UKMO etc )

[Kirkcaldy Weather]

Flash flood threat particulary given already sodden ground for Ireland, Northwest England and Scotland as a cyclonic system develops along the boundary between cooler and milder airmasses.

Tomorrow through Saturday.

With colder air undercutting from the Northwest this will turn the rain to snow for the Scottish Highlands.

As this colder airmass descends into Ireland and the UK this will bring Lowering temperatures including frost especially further north and northwest.

Overnight Fri > Saturday 

As an area of increasing instability moves into Central Southern and Southeast England on Friday Afternoon this could generate thundery showers.

There are multiple big snowfalls with one in Iceland and as the system from Ireland and the UK moves along the MJO feedback pathway per my previous post, this brings a snowfall event across Scandinavia.

Also linking to my prior post.

 

[WYorksWeather]

12z GFS ensembles

Steady as we go on the GFS ensembles. Significant warm anomalies through around the 22nd overall, then possibly a hint of something cooler. I hesitate to call it cold though when the mean doesn't even have temperatures low enough for a ground frost!

Again, just to show the lack of any cold here, even looking at Newcastle, it's the same old story. The mean says no ground frosts at all in the next two weeks.

12z GFS OP

In terms of the broader scale pattern, today's 12z GFS is continuing the settled idea. Most or all of the UK remains under high pressure from around day 8 to day 12 inclusive. The orientation of the high means that it's unlikely to be especially warm though, but the dry weather is probably more important at this stage.

The GFS then produces one of its traditional monster lows in deep FI which then tosses aside the high like Godzilla throwing a car, but it's hard to know what to think of that as it usually goes off on one with these ridiculous lows at that sort of range.

12z ECM OP

The ECM operational also shows some promise for more settled weather. We get a high set up from around day 8, and then holding until the end of the run. However, it doesn't quite reach as far north, so unfortunately it does probably mean more rain for the north and west. There is more of a north-south temperature split though with this pattern.

GFS and ECM ensemble means

Trying to reel this in from day 10 yesterday, here's where we are on the ensemble means at day 9. GFS and ECM are a little wobbly - the high possibly only grazing into the south-west. Let's hope the more amplified solutions from the OP runs end up nearer the mark.

Summary

In short, whilst the OP runs continue to provide a fair bit of optimism for a drier spell, we need to see this reflected in the ensembles, which at the moment still have too much scatter.

Hopefully though, we do get a drier spell, whether warmer or colder.

[Don]

9 hours ago, Mike Poole said:

It is far too soon to say whether this has just been down to bad luck, or whether the bar to clear to provide the forcing necessary to get blocking in the right place is now getting so high with climate change that SSWs are going the way of favourable MJO phases - i.e. just don’t seem to deliver any more.  Time will tell…

If that's the case, surely that would mean we have now  reached the stage of CC where cold winters are virtually impossible in this country?!

[MP-R]

More like a spring switcheroony than the monotonous crud we've had recently:

 

Bit more in the way of variation on tonight's GFS. Loving the prospect of high teens and sunshine in the first chart, and blustery showers that would probably bring hail/sleet/snow in the heaviest bursts in the second chart.