Model Output Discussion - Spring Has Sprung

[IDO]

The GEFS mean has been solid for FI, and it really looks like up to mid-March, nothing interesting for the UK, snow-wise. The 0z:

 

We are on the cold side of the jet but only scraps of colder 850s for the UK. The obvious negative is that there is no amplification of the NH, which is a sign of winter, so we are relying on the tPV to create something. The mean suggests it moves from our NW to the Arctic, which is invariably useless for the UK. The other negative is the omnipresent Russian/Siberian high, which has meant the latest cold push has been west-based, hence the washed-out uppers. GEM at D10, for example:

So even when a wedge of heights (all models around D6-7) breaks through the UK trough and heads east through Scandi, the resulting pattern is west-based for the UK. There are some colder uppers but little of note for snow for most. London:

 

The 850s and 2m temps are all, rather meh. Sums up this winter.

[Dennis]

good monday all

Edited February 26 by Dennis

[Jordan S]

On 24/02/2024 at 14:43, Jordan S said:

So beyond 3rd, increasing chance of those drier and milder temps for southern uk temporarily with higher pressure more likely than not making an appearance to our south/southeast, though it’s important to note given the models themselves are undecided, I wouldn’t want to sound certain of this but still confident. 60-75% chance would be a good estimate.

 

Western and more especially northwestern areas of the UK again more likely to remain unsettled at the same time 3rd-8th and possibly less cold, but still with temperatures around average to slightly colder than average in places in the northwest..

If we take this morning’s model updates at face value, perhaps more widely drier conditions for a few days than just for southern and eastern areas that I’ve been anticipating? 
 

Certainly now a possibility, though most likely a west/east split until around 8th from 3rd/4th with drier weather east and a bit unsettled west/northwest which would be a slightly better outlook than I suggested recently, even with my eye on drier weather probable developments over southern and eastern areas for the same period.
 

So a 3-4day more widespread settled spell and a bit milder? Would say now a 30-40%

west/east split ? 40-50% 

Only southern and southeastern parts of UK being drier and milder? ie what my previous updates have suggested ? 10-20%. 

The overall synoptic pattern isn’t expected to be any different really overall if we compare to what I’ve been saying, so that by around 10th unsettled conditions are more likely still overall to be nationwide again, with southern regions liable to be wetter than Scotland by then. By mid month northern areas may see more longer spells of dry weather with lows over the south/southwest. This last part is rather similar.
 

Have a good day all hopefully we see some drier conditions more widespread than just southern and southeastern areas for a time after cold unsettled first couple days of March.

[ANYWEATHER]

Well let's hope the models are singing the right tune........☺

[Markus03]

 andymusic Interesting, it shows that where I live snow is gone by then. Also it makes sense because forecast changed entirely. It looked like cold was coming and dry. But now Southerly winds continue and there will be rain . Rain really helps the snow to melt. That's too early for Scandinavia. I'm laughing right now.

[Met4Cast]

AM tendency is rising once again thanks to another strong (albeit likely brief) +EAMT event. In terms of the broader patterns going forward though I'm struggling to see much in the way of a trop response to the SSW next week, MJO forecasts have been all over the place and I suspect we're seeing influence from the SSW there skewing modelling somewhat but general consensus appears to be out of the COD into phase 4/5. In early March this correlates to stronger S European heights and a flatter zonal Atlantic jet (there's a surprise).

With the recent sharp fall and rise in AAM tendency it does seem plausible that we'll see the jet stream encountering some road blocks in the form of high pressure, probably to the NE of the UK (though as mentioned previously, the high probably too far NE to influence the UK much) before the pattern flattens out again by the end of week 1 into week 2 of March.

Broadly +ve and -ve anomalies are propagating poleward now so a brief relaxation of Iberian heights and a more amplified jet does seem plausible next week but again, not sure it'll be in the right place to influence the UK in terms of colder weather. For the UK at least, a continuation of mild & at times unsettled weather seems the favourite going forward, just to make a change.

Quite a tricky period to try and "diagnose" but I've given it a go anyway! This is fairly low confidence. 

Interestingly the Met Office extended forecast suggests the opposite of this & currently favours blocking/colder temperatures to take hold post March 11th so will be fun to watch that evolve!

[Neilsouth]

I really don't care about cold weather, it's been cold enough already...

 Is there ANY sign in the model output of dry weather? The river burst its banks here, so

[Rain All Night]

On 24/02/2024 at 22:42, Rain All Night said:

12z/18z deterministic runs, Sun 25th to Sat 2nd (day 7)

12z ensemble means, Sun 25th to Sun 10th (day 15)

The point at which this next trough drops over the UK, which is now crossing into "week 1", and which by now feels like we've known it's coming for an age, really does seem to be quite a fork in the road for the models; it remains completely unclear what will follow this event. Heights to the east and mild air flows from south of west remain modestly signalled.

It still seems there will be a moving of the furniture upstairs in the stratosphere throughout the first week of March. Whether or not this has anything to do with the model uncertainty beginning at around the same time is above my pay grade.

0z/6z deterministic runs, Mon 26th to Mon 4th (day 7)

I see that in the 36 hours or so since my last post, the immediate aftermath of the arrival of the next trough over the UK has been revealed to us: it will be sucked back into the Atlantic, while a part of it splits off to the southeast into Europe.

0z/6z ensemble means, Mon 26th to Tue 12th (day 15)

Once that next trough has departed, we might be able to swing a dry spell from the build of heights to our east, perhaps even a brief southerly airflow.

Then, there is a signal for a new trough perhaps becoming a cut-off low to our southwest from around 8th March (day 11) onwards. Depending on how close that sits to us, we could either get a nice dry continental air flow, or buckets of Atlantic rain.

Oddly there was no GEM ensemble out on Meteociel this morning.

Edited February 26 by Rain All Night

[carinthian]

Evening all , just looking at that latest chart for months end. Another pulse of warm air heading into The Eastern Alps. So far up to 25 th Feb , it is the warmest February ever in 257 years of records kept in Austria. Nearly a massive +6c  above the 1991-20 average ( that is also a period of warm decades ) Some parts of Austria not seeing any snowfall at all this winter. Quite astonishing.

C

[WYorksWeather]

Still not much sign of a consensus on the situation as we go deeper into March from the GFS tonight. Drier does look like a fair bet looking at the MSLP charts with a fair cluster going that way, but still too many keeping the unsettled theme going. Temperature wise it looks like we're going to be sticking around average for the foreseeable - possibly a little below on 1991-2020 at times, though likely still in line or slightly above on 1961-1990.

In short, no sign of a return to winter, or anything properly spring-like, just near average. Drier looks likely, but far from a sure bet that it will be a proper dry spell, as opposed to just less unsettled than of late.

 

[winterof79]

Interesting.

Edited February 26 by winterof79

[Ali1977]

 winterof79 is take that chart ️️15-20 Cm!! Unlikely but plenty ens showing it 

Edited February 26 by Ali1977

[WYorksWeather]

Interesting divergence between GFS and ECM. ECM much more enthusiastic about something warmer than GFS.

ECM still showing another SSW. However, the vortex then does return to positive territory, so it may not be a technical final warming.

 

[feb1991blizzard]

This charade just illustrates how garbage the modelling has been this winter, Ali1977 you're quite right there's decent ens support for a decent dumping at day 5 as far south as the south midlands, however every respected forecasting organisation says a N Pennines affair at best, probably Scotland and 7-11 max temps.

 

Edited February 26 by feb1991blizzard

[stodge]

Evening all

A lot of uncertainty across the 12Z suite this evening.

The LP later this week is the first problem - the negative alignment drops the trough south on Friday which could be quite an unpleasant wet, cold day but beyond that will we see a clean ejection of that energy south? It seems not as in the face of blocking to the east the LP eases back west and re-enforces the Atlantic trough leaving the British Isles in a mild, very mild or even warm stand off by the end of the week after next.

One option would be for northern blocking to extend from Scandinavia to Greenland dragging the trough south and introducing a mild ESE'ly flow (again far from unusual in early spring). 

12Z CFS is by contrast a nirvana for cold and snow fans but I suspect this won't happen.

[Rain All Night]

7 hours ago, Rain All Night said:

0z/6z deterministic runs, Mon 26th to Mon 4th (day 7)

I see that in the 36 hours or so since my last post, the immediate aftermath of the arrival of the next trough over the UK has been revealed to us: it will be sucked back into the Atlantic, while a part of it splits off to the southeast into Europe.

0z/6z ensemble means, Mon 26th to Tue 12th (day 15)

Once that next trough has departed, we might be able to swing a dry spell from the build of heights to our east, perhaps even a brief southerly airflow.

Then, there is a signal for a new trough perhaps becoming a cut-off low to our southwest from around 8th March (day 11) onwards. Depending on how close that sits to us, we could either get a nice dry continental air flow, or buckets of Atlantic rain.

Oddly there was no GEM ensemble out on Meteociel this morning.

12z deterministic runs, Tue 27th to Mon 4th (day 7)

It looks like a case of things getting worse before they get better... though at least these charts are a reminder that high pressure over Europe can yield, when it wants to.

12z ensemble means, Tue 27th to Tue 12th (day 15)

Similar to this morning, but with that low signal to the southwest from the 8th not quite as strong.

[Pauski]

 Markus03 yes looking bad for Finland. 

12 hours ago, Markus03 said:

Interesting, it shows that where I live snow is gone by then. Also it makes sense because forecast changed entirely. It looked like cold was coming and dry. But now Southerly winds continue and there will be rain . Rain really helps the snow to melt. That's too early for Scandinavia. I'm laughing right now.

Yes looking bad for Finland. 

[Ali1977]

 feb1991blizzard no doubt be gone by the next run, it’s been a very very bleak winter for many snow lovers this season I’d still take something In early to mid March Though 

[damianslaw]

Quite an unusual outlook as we enter March, but, perhaps not given Spring often delivers synoptics that verify far less than in other seasons..

A deep trough anchoring south, but not able to eject cleanly due to rising pressure to our east, instead it is forecast to sit in situ over the UK and advect west and join hands with upstream trough. A rather chilly wet start to the month likely.

Into early March further a signal for heights to our east, and trough to our west/ sw.  A SE flow but not a cold one most likely outcome, could deliver a spell of dry weather at least, but possibly rather grey and dull, mild but not especially so.

All attention of what happens to those heights to our east, will the trough eventually go under, something that eluded us this winter, but quite naturally more likely into spring. 

Edited February 26 by damianslaw

[Kentspur]

 winterof79 Thats a funny coincidence as im off to the West Midlands late on Friday night to my friends would be lovely to wake up to a white blanket! Hoping to see some sites up that way Warwick Castle looks cool. Ive heard mixed reviews of Cadburys world

 damianslaw EC46 showing Greenland and Iceland Blocking and more North of East flow after this supposed S&SEly flow by late March

Edited February 26 by Kentspur

[Mike Poole]

Just perhaps worth watching a possible easterly setup around the 10 day timeframe.  Clusters at T192-T240:

Cluster 2 (25 members) showing more organised heights to the north, this was there in the extended clusters yesterday with just 11 members, so maybe an increasing signal.  Some work to do to get from there to a proper easterly flow, the low to the SW would need to go under, or keep well away, and for any cold interest at this time of year, flow from anywhere south of east would not cut it either.  But this would be post wind reversal in the strat, so worth watching as the models sort themselves out after that.

[Anthony Burden]

Morning all,ECM very interesting at the unreliable 216/240 hrs with a Scandinavian block that has mild 850 hpa with a south/easterley feed but that could change very quickly into much colder air stream,one to keep an eye on possible SSW showing it’s hand.

[Cambrian]

Much cleaner evolution to an easterly flow on the 0z ECM op, which adeptly delivers an unorthodox 1-2-3 left jab / right jab / uppercut combo to put paid to the trough. 

In slow motion, first the jabs, at days 4-6, the left jab from the Atlantic heights heading north, in tandem with the right jab from the heights over Eastern Europe also pushing through to north of Iceland.

 

Then the upper cut, days 7-10, delivered by a quick hit of Iberian heights, pushing up to reinforce the pressure being exerted to the north - indeed unlike other recent challengers, critically getting sufficient heights far enough north - and resulting in the isolation of the cut-off low at the base of the upper trough, now much weakened and pushed west, but not before some energy ejects southeast from the trough into southeast Europe at day 7…

 

…the upshot of all this being the establishment of an easterly flow through Europe, extending the continental feed into the UK and Ireland. 

Even some support from the ensemble mean old judges at day 10, with the surface high holding over Scandinavia and a southeasterly flow. 

 

At this stage, looking increasingly like a points decision for a very welcome drier spell. 

[Addicks Fan 1981]

 Kentspur I think we need to keep our eyes on the MJO as I don't think the EC46 is the right thing to be using now.   The MJO which @Kirkcaldy Weatherposts later will give us a lot more clout of what is going on.   

[Ali1977]

GFS showing more snow around on Friday this morning, high ground even in the far south.