Model Output Discussion - Spring Has Sprung

[feb1991blizzard]

ECM 12z joins the party.

[Cambrian]

ECMWF coolly trying to pass this one off as the 0z ensemble pressure plot for the next 10 days. They’ve even gone to the lengths of publishing accompanying charts that show an Atlantic trough being disrupted as it gets forced around the southern flank of a Scandinavian high, making most inroads around day 4, before being broken up, the cut-off low heading into northern France and the remaining stem of the trough getting pushed back west, at least for a while.

 

But those computers have been caught red-handed in what is clearly a poorly disguised analysis of the number of posts on the model thread, starting heading into December, the phrenetic activity peaking around Christmas and the New Year, then falling away steadily, each month is craftily concealed as a day, the current quieter March to April period corresponding conveniently with the squeeze from the trough. 

Then we’re in to their current prediction for the next few months, featuring a resurgence between Easter and June, peaking with interest in potential heatwaves between June and August, before falling away again towards the autumn. 

Evidently modelling more than just the weather, but we’re on to them - you’re fooling no-one here, Reading. 

[Rain All Night]

12 hours ago, Rain All Night said:

12z deterministic runs, out to Tue 12th (day 7)

On GFS and UKMO, it almost looks as if the block could find a way to hold out...

12z ensemble means, out to Wed 20th (day 15)

The ECM ensemble still wants to believe that there might be a way to stall the Atlantic advance. Not sure why some of the frames have glitched out, mind you...

0z deterministic runs, out to Wed 13th (day 7)

Would be nice if that Atlantic trough would at least drag up a bit of warmth ahead of it, as suggested by the GFS.

0z ensemble means, out to Thu 21st (day 15)

ECM is gradually giving in to GEFS on the Atlantic threat post 13th March. It is also showing a somewhat eye-catching height rise in deep FI...

The clusters sitting behind that ECM deep FI height rise:

Edited March 6 by Rain All Night

[Gowon]

A big 'ol beast is taking shape right at the end of the GFS:

  

 

[Cambrian]

Once the low detaches from the trough and trundles by to the south, the 12z ECM op sets up a distinctly cold looking high pressure over the UK and Ireland by day 7. Animations here through to day 8. 

  

The high pressure squeezes around the northwestern flank of the departing low, bringing cold air with it from Scandinavia and delivering some sharp looking uppers. Could be a bit crisp that. 

[carinthian]

I would not like to be on The Yorkshire coast this weekend with winds coming off The North Sea. Will feel even colder next week. There is a heck of a lot of snow to melt and transfer into the North Sea from Scandinavia over the coming weeks. Any winds originating from the East will make Eastern parts feel particularly cold. Models showing that now. Even today with coldest I have ever felt in my lifetime was playing cricket at Wetwang ( Yorkshire wolds ) in early April wearing 3 sweaters. Currently living at 1340m in the Austrian Alps and positively mild in comparison to ! Wetwang , frozen in time. Great place and happy memories.

 C

[Anthony Burden]

Evening all,ECM showing the colder outlook with positioning and orientation of high pressure still all eyes on SSW and what happens around the middle of March to high level blocking.

[Metwatch]

Looking at the 500hPa geopotential height and pressure chart for this weekend:

Then checking the airmass and seeing there's virtually no cold air ahead of the low pressure:

[Jordan S]

On 02/03/2024 at 21:22, Jordan S said:

colder upper air temperatures already in the north very slowly envelops the rest of the UK within a developing anticyclonic weather pattern over the UK towards mid month.

Ecmwf again today a good example of the above, before the Atlantic lows begin to make their move across particularly southern UK post mid month. 
 

[WYorksWeather]

GFS still not budging. No predictability beyond 12th/13th at this stage, though near average conditions are still favoured.

The mean for day 7 looks fairly non-descript - there is a Scandinavian high but it's not really bringing any cold air our way.

In terms of uncertainty, the broader scale pattern over Scandinavia looks pretty well fixed, but there is a lot of uncertainty as to the pressure anomalies directly over the UK and immediately to our west. If that low to our west would stall a bit more we might have a chance of a drier interlude, but at the moment it does look like at the very least western areas will be unsettled at day 7, with perhaps the best of any dry weather further east.

The GEFS 2m temperature stamps do show that we're a bit in the doldrums at the moment - very low chances of anything cold, very low chances of anything truly spring-like at day 7. No ensembles keep daytime temperatures widely close to zero, and none go very mild either with widespread mid or high teens.

Further ahead, at day 14, we see a bit more scope for variation, with quite a few mild runs but also a few on the cold side (probably too late for snow though for most by then). But it's not really a clear trend, the signal-to-noise ratio is pretty low, frankly.

The wait for something interesting (either warm or cold) goes on with the GFS 12z.

[ANYWEATHER]

Lovely Winter charts showing up now........

[Bricriu]

Am I the the only one still hoping for snow? I don't want to wait another nine or 10 months for snow. I hope the proper reversal  of the Zonal  Winds this time will lead to the mother of all northerly (-14 -16  uppers over Scotland  and Northern Ireland and -10 -12  everywhere else) during the final third of March. I know it's  a pipe dream!

[Sky Blues fan]

 ANYWEATHER yep just when we’re all fed up of this S……. weather and we need a bit of warmth

[WYorksWeather]

 Bricriu You'll be holding out for something like this then.

 

There is something of a signal for another cooler spell around 11th-13th or so on tonight's ECM, but the issue is that the bar now is so high. You need an absolutely phenomenal signal to get snow to fall to low levels and then to stick around for any length of time. The hammer blow is that there are so few ensembles getting down to the -10C range even as far north as Newcastle.

Really depends on what you're hoping for. A brief snowfall is still very much possible. But if we're looking for at least a few centimetres to fall widely to low levels and last for 24-48 hours or more, then the odds are very low. Of course never say never.

[Rain All Night]

11 hours ago, Rain All Night said:

0z deterministic runs, out to Wed 13th (day 7)

Would be nice if that Atlantic trough would at least drag up a bit of warmth ahead of it, as suggested by the GFS.

0z ensemble means, out to Thu 21st (day 15)

ECM is gradually giving in to GEFS on the Atlantic threat post 13th March. It is also showing a somewhat eye-catching height rise in deep FI...

The clusters sitting behind that ECM deep FI height rise:

12z deterministic runs, out to Wed 13th (day 7)

Wow, what a mess! It's anyone's guess where we're going after day 4 at the moment. In a way, that makes things quite interesting. Personally, I'd take a southerly, which does seem to be on the table.

In the later frames, I kind of get the vibe that there's no particularly strong force driving the weather in any particular direction at the moment. Which is perhaps quite a spring-like state of affairs?

12z ensemble means, out to Thu 21st (day 15)

Now the roles have reversed, and it is ECM that is more progressive with the Atlantic earlier on! All three, though, show signs of height rises later, as the ECM did this morning, though not quite as strongly.

The ECM clusters for days 8-15:

[CoventryWeather]

Modelling looks pretty average for the time of year - fairly bog standard spring weather. 

I'm not expecting another washout in the mid range, if anything I would expect a weakish high near to the UK. Say the ECM/UKMO is probably near to where I would expect it to head. 

Extended range is rather uncertain with the reversal, but again not convinced it will lead to anything cold. 

[nobble]

 Bricriu nope still hoping here

[IDO]

I don't know what happened with yesterday's EC 12z. It was one of the biggest outliers I have ever seen. So, it is no surprise that the 0z is different and more representative of the mean. The model op runs are all struggling with the next ten days (post-D5), but none offer anything freezing, just run-of-the-mill March changeable weather. There is still a chance post-D5 for the UK to be clipped by some transient colder uppers, but nothing remotely blocked or sustainable for anything worthwhile for snow and ice. London GFS ens:

 

We can see the border between the Atlantic and the Euro high via accumulated rainfall on the GFS op:

A NW-SE split.

Post D9 on the GFS mean and a mean Bering Sea HP forms, which could mean a change in the pattern as the tPV still appears to be driving the NH pattern:

Though no tropical forcing is evident, the SSW does not get any help from upstream waves to speed up the cold moving south. There have been three SSWs this year, and if we want any proof that they are not as big a deal as hyped, then this winter bangs that home.

[joggs]

Not good output for cold,snow(if you're still looking for that) or spring warmth.

It's been a very depressing 8 months or so and looks like carrying on.....zzzzz

[MJB]

White Easter en route   

JFF ,so put your guns away 

[mountain shadow]

 MJB More likely than a White Christmas of course.

[Weather-history]

 mountain shadow

 

[LRD]

 mountain shadow Ah, man, not that old chestnut again. It is just NOT true

Anyway, not too much to worry about in the ensembles. Average and doesn't look too wet IMBY. Just hope the sun comes out occasionally. Hopefully we'll experience a big warm (and dry) up towards Easter and into April. That'll soon be in the range of the everyday GFS output

Edited March 7 by LRD

[Jordan S]

On 05/03/2024 at 00:34, Jordan S said:

for the mid month period/slightly before, reiterating the outcome and lows over southern areas as expected, clearing away slowly to our south and east with higher pressure likely moving over large parts of the country drying things out for a time once again for the 12th-14th along with slightly colder upper air temperatures of between -4c to -7c or perhaps -8c and this Ecmwf and now Gfs update shows this well, the window of drier weather may be shorter lived around this time frame if some model runs are to be believed, though more likely a case in reality of rain bearing fronts/low pressure system developing at short notice just to the west of the UK perhaps briefly interrupting an otherwise a developing anticyclonic weather pattern over the UK but the Ecmwf pressure pattern forecast should be largely representative of what will happen.

Morning guys,  Subtle changes to the quote above here being the low out west more influential just before mid month (not talking about the lows in the next few days) but was highlighted as a possibility in my previous update, when high pressure tries to stay in charge of the UK just before mid month still but low to our west possibly interrupting an attempted developing anticyclonic pattern, spreading possible rain northeast across western and northwestern areas with snow on much higher ground possible. 

On 05/03/2024 at 00:34, Jordan S said:

The main takeaway beyond mid month being? Northern UK, increased albeit now lower risk than thought previously of northeast winds trying to establish over parts of the country and increased risk of sleet/snow showers especially on high ground, though unlikely to be anything exceptionally cold, typical spring wintriness to be honest if this does indeed play out, doesn’t rule out more persistent wintry precipitation, this increasingly from advancing north/northeast moving frontal systems from the south and west and whilst trending less settled in the north with winds possibly changing to a milder southerly or southeasterly with time, Again it isn’t likely to be as wet as southern areas of UK, with longer drier spells and higher pressure overall, especially in the far north. But for southern UK frontal systems moving north/northeast is more likely still, with again very mild air trying to establish over the UK, temperatures may trend somewhat above average in sunny spells in the south/southeast but otherwise feeling rather cool in any wet weather even with reasonable upper air temperatures here. Potentially much warmer than average for a time over Western Europe mainly along eastern parts of Western Europe ie eastern Spain and then into eastern France even in an otherwise very wet and unsettled cyclonic pattern overall, with winds likely originating from North Africa and higher pressure traversing northeast from Spain then moving north through Central Europe.

Not much to indicate much has changed with my thinking from yesterday.

The Gfs seems to want to go with this above quote to a large degree in its latter frames, with the increasing chance of northeast winds into the north with snow showers and the risk of more persistent wintry precipitation once again being possible from advancing weather fronts moving northeast into northern areas from the south, with higher pressures tending to float around to our immediate north/northwest ie more Greenland as said previously, the wettest weather which will probably be all rain still looks to be for southern UK overall, with very mild air trying to establish further north into the UK aswell still likely, on the whole it does still look like often being drier in the north with some pleasant spring sunshine in the latter part of March but some colder nights could be a feature in any absence of winds from our south, potential is still there for southern and southeastern areas to tap into some warmer than average temperatures after mid month in an otherwise cyclonic wet spell, but there will be some drier days even here ofcourse, so yes looks wetter than average for March here but not as much as February.

Very low chance <10-15% of widespread very cold northeast winds and wintry showers in south and snow persistent snow showers in north beyond mid month, this would be fairly akin to an update I made I think about a week ago for the same period highlighting that perhaps being more likely, ofcourse risk lowered now.
 

The noaa chart below again shows the outlook anticipated well with heights likely to be prevalent near/over Greenland with any unsettled weather largely over southern UK and especially further south slightly still.


 

Edited March 7 by Jordan S

[Rain All Night]

14 hours ago, Rain All Night said:

12z deterministic runs, out to Wed 13th (day 7)

Wow, what a mess! It's anyone's guess where we're going after day 4 at the moment. In a way, that makes things quite interesting. Personally, I'd take a southerly, which does seem to be on the table.

In the later frames, I kind of get the vibe that there's no particularly strong force driving the weather in any particular direction at the moment. Which is perhaps quite a spring-like state of affairs?

12z ensemble means, out to Thu 21st (day 15)

Now the roles have reversed, and it is ECM that is more progressive with the Atlantic earlier on! All three, though, show signs of height rises later, as the ECM did this morning, though not quite as strongly.

The ECM clusters for days 8-15:

0z deterministic runs, out to Thu 14th (day 7)

Must admit the crappiness of most of the later frames on these runs has taken me a little by surprise, UKMO excepted. Oh well, who needs a dry second week of March anyway, it can wait until the days are longer and the sun is stronger.

0z ensemble means, out to Fri 22nd (day 15)

ECM is continuing its newly-assumed role as the bad cop earlier on, but still offers the intriguing height rise signal - focused to the west of the UK - later on, and the other two models show some signs of this as well.

The ECM clusters from days 8-15:

Edited March 7 by Rain All Night