Model Output Discussion - Spring Has Sprung

[AO-]

 Dennis

It will be hard I guess, but not impossible as the uppers at 1,5 km are "only" -4. In intense showers it should be possible. But the wind direction is Southwest. What is the sst near the coast?

[Cambrian]

0z ECM ensemble mean is useful for “removing the noise” and showing the core pattern for the next 10 days. 

It’s a recurring one, the PV over Arctic Canada spawning a succession of low pressure systems that move southeast towards the base of the trough over Western Europe. 

Two systems push their way through a gap between Atlantic and Scandinavia / Russia heights, with a third one ready to drop out of Greenland by day 10, shown more clearly on the anomaly chart. 

 

Also nicely shown on the anomaly charts are the episodes of heights building over eastern North America, that then run in pulses along the ribbon of heights through the Atlantic. 

These pulses are helping to push the systems down from Greenland but are struggling to establish a base into Iberia, with the jet stream diving so sharply southeast over the eastern Atlantic, keeping it changeable with temperatures close to average overall. 

On a closer look, milder for a few days in the middle of the spell as winds turn into the west riding over the top of the Atlantic ridge, 0z EPS jet stream at day 6…

  

…before turning colder again around day 8/9 as the next system drops down from Greenland, reinforcing the trough over Western Europe, the UK and Ireland by then back on the cold side of the jet stream.

[ANYWEATHER]

 Dennis what do you mean ??? Please clarify?

[feb1991blizzard]

 ANYWEATHER

He means snow possible to fairly low elevation.

[Jordan S]

On 16/02/2024 at 14:51, Jordan S said:

precipitation entirely as rain in the south at first though showers by next weekend could turn wintry over some hills of Wales and southwest England in heavy showers.

Highlighting what I mentioned for this weekends showers being possibly wintry for hills of Wales,southwest England for this weekend. Definitely some risk of those showers being wintry though maybe not the southwest.

On 16/02/2024 at 14:51, Jordan S said:

We probably see a relaxation of the northwesterly beyond next weekend especially by the 27th as the high to our southwest moves closer to the southwest temporarily as hinted in previous couple of posts though this expected a couple days later, so should see slightly less unsettled conditions in the south for a time and a bit milder here, temperatures look like remaining around average or a little below in the north though but less so than the days preceding it with winds more westerly across the UK as a whole later 27th - 1sr March.

Okay this does look like going pretty much exactly as expected when yesterday it was under some question just how quick the westerly winds would return during 27-29th, apologies for the temporary slight doubt yesterday, I think those rogue Gfs runs of messy synoptic development for the time period puzzled me but planted some brief doubt in my own thoughts.

Seems the track of Sunday’s low pressure system was the reason behind subtle differences in the synoptics for early next week from the Gfs. Centre of low pressure for Sunday moving over far southwest then into channel and France with the high risk of persistent rain into southern counties of England and perhaps Wales, a moderate east/northeast wind making it feel distinctly cold, but feeling more pleasant in sunny spells to the north of the rain and cloud.

 

On 16/02/2024 at 14:51, Jordan S said:

Into first few days of March though and we could see a brief return to northwest winds as high amplification to our west strengthens, though a link up to Greenland from the mid Atlantic high at this stage is unlikely but not to be ruled out entirely. Temperatures may trend slightly below normal briefly for all with unsettled conditions widespread once again, relatively cold and cyclonic to end the month and beginning of March sums it up generally even with the relaxation of the colder pattern if it does occur.

The above quote looks largely accurate.

On 16/02/2024 at 14:51, Jordan S said:

I think this will be brief, before looking slightly further into the first week of March and after a likely cyclonic and relatively cold first couple of days for all, patterns are liable to stagnate even more in the mid Atlantic after the preceding stronger jet stream of late February, weak high pressure may form over Greenland and this should keep lows on a more southerly track but with heights increasing to our south/southeast as well later in the first week of March there’s an increasing chance of very mild or even fairly warm conditions moving into southern and eastern areas temporarily, partly driven by areas of unsettled weather moving steadily into western areas drawing up southerly winds, possibly giving the first 20c of the meteorological spring in the south and east of England along with drier though not completely dry conditions for these areas and overall staying very unsettled in the west and north, temperatures around average by then in the north.

This above quote does look largely accurate so far. Gfs this morning a textbook example of the brief warmer and drier south increased possibility, with heights building to our south and southeast bringing winds more from the south, maybe not 20c though, but mid to high teens certainly achieve-able, not to say it’s certain but gives even more confidence to the synoptic occurring. 

We will see how this evolves as the time period gets closer. 
 

I still don’t think it will be long lasting though (more than 3 or 4 days) before cooler and unsettled conditions return a few days later. Which would take us to around 8th- 10th March. 
 

Have a good day all.

Edited February 22 by Jordan S

[Rain All Night]

23 hours ago, Rain All Night said:

0z deterministic runs, Wed 21st to Wed 28th (day 7)

GFS has this morning 'capitulated' to the ECM's depiction of the toppling Atlantic ridge - but of course, nobody is paying much attention to that, since none of the suggested outcomes on either side have been especially interesting for the UK.

0z ensemble means, Wed 21st to Thu 7th (day 15)

As with the op runs, the shift of the GFS ensemble towards the other two models is noticeable this morning. They're all now showing similar progressions into the first week of March.

We have a new signal emerging in that first week of March, which is for a build of heights to our east. It's too early for me to guess at the possible impact of this at present. The GFS ensemble allows this signal to fade away into deep FI, but the ECM and GEM hold it in place.

0z deterministic runs, Thu 22nd to Thu 29th (day 7)

Nothing new here really, though I note from other posts that there's some interest in whether the low on Sunday could miss us to the south entirely. Regardless, pressure contours looking slack over much of Britain for a while on Saturday and Sunday.

0z ensemble means, Thu 22nd to Fri 8th (day 15)

It feels like we're learning ever so slowly at the moment. We've known about the next trough attack around 29th Feb/1st Mar for days, but still have little signal beyond that. My one concern, based on the raised heights to the east that have been showing up on some of the ensemble means into the first week of March, is that we could end up with troughs getting stuck over, or just to the west of, the UK with no way to exit.

I hope the upcoming stratospheric event can do something to get rid of the tedious TPV to the northwest.

Edited February 22 by Rain All Night

[feb1991blizzard]

That is the one we want, a proper burial job.

That would bring memories from Dec 2010 for Liverpool & preston flooding back.

 

[Rain All Night]

That was a LONG silence for this thread in winter!

[blizzard81]

Well I have to admit that my predictions for Feb were spectacularly wrong! It's been a peculiar winter in many ways. One of the wettest up here that I can remember. Absolutely abysmal. 

[CoventryWeather]

Hints latter mid range for something drier developing. 

Both the GEM and GFS on that path. Mentioned the chance of it the other day, but got spoken down due to it being outside the 'reliable'. 

The GEFS have been interested today around day 10. 

[Metwatch]

1 hour ago, Rain All Night said:

That was a LONG silence for this thread in winter!

[blizzard81]

A nice, meaningful Scandi high - just too late - again!

[Tim Bland]

Day 9 & 10 has a dusting …seen loads of snow at day 9 & 10 this winter…not a single cm at day 0 though

[nick sussex]

 blizzard81

It has been a very bizarre winter . The strat forecasts which have in the past been reliable have bitten the dust . We’ve had some decent ingredients but have ended up with the food equivalent of Spam !

It will probably go down as the biggest recent failure in longer range modeling.

 

[beefy201]

A few days of a colder weather meaning less rain before more cold rain and winds looking like early spring warmth from 2nd week of March but shhhh don’t anyone warmth without rain

[stodge]

Evening all

After we get through this weekend's fun and games and both Sunday and Monday look particularly unpleasant in the south with the LP over southern counties on Sunday and easing SE into France on Monday leaving us in a short lived NE'ly.

Normal service tries to resume but by Thursday another trough is digging south over the British Isles - 12Z GFS OP disrupts this splitting the energy and allowing heights to build in the col. Other models are less keen to split the energy and keep the cold trough over us through into early March.

From there, who knows? KMA might be some people's idea of the answer but I remain to be convinced though it's nice to look at. 

As for the 10 HPA, repeated warmings keep the PV unstable but intact promoting cooling in response.  How this will play out as we go through March I'm not sure - there have been plenty of forecasts suggesting a zonal wind reversal so we'll see.

I like March and April - interesting synoptics especially if we can get some serious northern blocking and a contest between the colder and warmer air masses - we know who wins every year but the battles can be interesting.

[Mike Poole]

 nick sussex Yes, the strat modelling has been diabolical all winter.  I suspect it is to do with the strat vortex never getting properly going after the Canadian warming in December, the trop seems to have been dictating things since, even up to 10 hPa at times, and this has meant that the modelling has been unreliable because the trop evolution is unreliable - usually the strat vortex is easier for the good models to predict over a longer timescale but not this year.  

ECM 46 getting us ready for the next embarrassing strat climbdown (number 4 if I haven’t lost count), here’s the zonal winds forecast today on left, yesterday on right:

You can see a number of trends here, first the early peak is quite a bit higher, the plunge afterwards has a lot less going for it, the mean reversal is much less.  Anyone else reckon, come the day, it’ll end up just touching the zero line again, or maybe just a little below?

You have to laugh, after all, it doesn’t matter now, it’s all too late for snow…but this winter, Christ on a bike!  The modelling has been dire, the teleconnections have been dire, the strat predictions have been dire, and - the actual weather has been dire!  I honestly think I preferred the +IOD nightmare of 2019/20 - never any false hope there, was there?

Edited February 22 by Mike Poole

[Stephen W]

@Mike Poole

Your last para sums it all up perfectly, dire!! A winter that held such promise but didn’t just disappoint but went majorly bust on many fronts!!  I never thought we’d end up with one of the warmest Febs on record.

And yes, yet again the strat forecasts are trending in the wrong direction today. 

Worn down by this winter is an understatement.

 

[stodge]

Here's the thing - looking at the 10 HPA from the GFS 12Z OP we see repeated warmings from the European and Siberian side.

Now, as the strat warms on one side, it cools in response on the other and I suspect we see an increase in zonal winds between the cold and warm areas. We actually need to see an end to the warmings because that tends to equalise the 10 HPA temperatures across the northern hemisphere and would also lead, I suspect, to a slackening of zonal winds.

That's how I see it - I'm doubtless wrong.

[raz.org.rain]

 beefy201 yes, I'm somewhat confident that from the second week of March we'll start to see something much drier and warmer too. The Iberian highs are less eager in the model outputs but have been replaced with a persistent Azores high that's trying its best to reach our shores.

[minus10]

Main thing of concern down here in the south is the amount of rain...another 12mm here today...thoroughly miserable day...ground beyond saturated...

...so far this month here as recorded by my highly untechnical rain guage we have had 106mm...and eight of the last ten months well over 60mm rain has fallen..

..hoping as per gfs 12z fi that this will allow some drying out..

...however accumulated prec charts for day 10 gfs and ecm still show south and west catching lions share of the rain..

...and a very wet France, particularly the south and northern tip of Iberia...

...some hints at higher pressure according to the ens..

....although as seems to happen a lot lately with the gfs op it is an outlier later in the run.

..all a bit tenuous....

...no longer interested in cold now...just want some dry or at least drier weather to be able to get out into the gardens....

[feb1991blizzard]

Big split in-bound.

 

 

[Kentspur]

 Tim Bland Hope so im off to the west midlands for a few days to my friends on that day lol slightly more chance of seeing any there than in mt low lying snowshield of an area not that many parts of England have seen much this winter

[Severe Siberian icy blast]

 nick sussex i was only speaking about this to my mate at the pub last night its showed alot of promise but its fell apart time and time again its been incredibly frustrating I read some very reasoned out articles and informative well put together comments on hear that all pointed to the same place which was a fun winter, its so fascinating though and that's the draw for us all! 

Winters sometimes the only thing that's kept me going in life lol what a disappointment

[WYorksWeather]

Still not much of a way forward at this stage. A lot of scatter around 27th-29th still, but some consensus on at least something of a warmup. Will it be enough to break the CET record?