Model Output Discussion - A cold start to Spring?

[Daniel*]

7 minutes ago, feb1991blizzard said:

yes - read this some time ago - thought it was less than 30 but stand corrected.

I remember Dr Simon Lee tweeting about it recently, seems actually opinions vary a little 20 or 30 consecutive days it’s not completely settled.

 

[The Enforcer]

Time for some more random GEFS charts from the same T+192 timeframe:

south-westerly

south-westerly to south-easterly

UK High

UK High

north-easterly

[bluearmy]

26 minutes ago, Daniel* said:

According to literature for there to be a distinct new major SSW at least 30 days need to pass with zonal wind in westerly this will not be met, therefore the SSW seen in mid February and further easterly reversals are all part of the same SSW event.

 

Of course this is true but that doesn’t mean the nwp won’t struggle to cope with the change in flow when it actually begins high up.  This showed on Sundays 00z runs so despite today being the tech reversal at 10hpa 60N, the last 24 hours of runs should be more accurate re taking the effects into account 

[Battleground Snow]

Decent looking ecm 06z control run at 144, ideally we want darker yellows and oranges appearing around Iceland, to draw  a stronger clockwise pull of air from the north east, and to also make the block more resilient.

A fair few of the eps are nosediving at day 6 too.

Edited February 27, 2023 by Battleground Snow

[bluearmy]

1 hour ago, Kieran1960 said:

Plus alongside the milder trends being shown met office is going for a drier and warmer spring likely hood 

Of course on a hemispheric level, if there are colder areas ref the ssw then there will also be milder ones.  That would say that glosea sees nw europe being one of those 

[ItNeverSnowsInWindsor]

8 minutes ago, Battleground Snow said:

Decent looking ecm 06z control run at 144, ideally we want darker yellows and oranges appearing around Iceland, to draw  a stronger anticlockwise pull of air from the north east, and to also make the block more resilient.

A fair few of the eps are nosediving at day 6 too.

We also need that vortex over Eastern Scandinavia to pull down stronger more unstable airmass from Norway.

[Ali1977]

21 minutes ago, Battleground Snow said:

Decent looking ecm 06z control run at 144, ideally we want darker yellows and oranges appearing around Iceland, to draw  a stronger clockwise pull of air from the north east, and to also make the block more resilient.

A fair few of the eps are nosediving at day 6 too.

That certainly looks like a stronger block need some upgrades on the 12z’s to keep the positivity going - and the chance of snow early next week 

[Lukesluckybunch]

15 minutes ago, Ali1977 said:

That certainly looks like a stronger block need some upgrades on the 12z’s to keep the positivity going - and the chance of snow early next week 

weather online..say there is a chance of sleet and snow in there week ahead..going by the models there is a slight chance!

[Battleground Snow]

Icon moving towards the ukmo idea of a more robust block.

Looking forward to seeing the ukmo 168 chart later.

[MATTWOLVES 3]

Again the 6z ens from mogreps seem to hint at those colder conditions getting into the NE and the East. We are definitely in the game.

Regarding met..The snow showers risk seems to be growing towards the North and East...with a risk of more general snow as time goes on. It's obvious now that the recent strat events are trying to leave a mark upon us. I would say the next 2 weeks are gonna be very interesting, and some areas are gonna be seeing snow...how much..where and when..tbc.

Edited February 27, 2023 by MATT TATTOO

[Ali1977]

T150 on the icon shows a huge swathe of cold heading towards us - stronger block as mentioned 

 

Winter is coming according to this run 

Edited February 27, 2023 by Ali1977

[Lukesluckybunch]

well that will do from the ICON

[EML Network]

Icon looking good cold air in place across Eastern side of the whole of the UK.

NE Scotland especially so

[ICE COLD]

Nice ICON T168

[Mike Poole]

ICON has the block much stronger T150 compared 0z T162:

If this is reflected across the 12z suite, then it means that the breakdown from the SW and trends in the ensembles by day 10 etc. people have been discussing this morning are all worth a pinch of salt if the models are underestimating the signal to build this block in response to the SSW.

[winterof79]

Last Monday 30th the Gefs and ECM ensemble for 5th March not bad considering the slating they get.

Today's mean also attached first 

 

Thinking this first cold episode is more MJO forced.

 

 

 

 

Edited February 27, 2023 by winterof79

[seabreeze86]

ICON improved but more room for improvement

Met office now starting to mention disruptive snow next week. They are favouring a battleground scenario 

[CoventryWeather]

13 minutes ago, seabreeze86 said:

ICON improved but more room for improvement

Met office now starting to mention disruptive snow next week. They are favouring a battleground scenario 

Right then, time for the sledges then!

I'm kinda on that path where models are underestimating the extent of the block towards Greenland, just like they have done over the winter. I'm feeling there may be a cold spell, and that models are overdoing the Atlantic or westerly momentum too much. I'd happily take a week of heavy snowfall and then for spring and plumes to arrive. 

[Mucka]

I thought this mornings output was the best we had yet for pointing to a cold spell.

Of the 3 main models 2 showed deep cold setting in while the 3rd which did not still had much improved ensembles.

As for whether the Atlantic undercuts in the mid range, it is as much about how far NW we get the core heights before it attempts to barrel through as the small differences in how the Atlantic is modelled.

Obviously the more Southerly track any low takes the better and the less deep any low is the further S it will track but however low pressure approaches it will also of course be affected when it comes against the block and energy is distributed accordingly.

The further W and S that happens the better but that depends on the where the low meets the block as well as the lows track and form.

How far NW the high retrogresses up to this point also depends on several moving parts with the key being how much forcing W there is from the Arctic trough to our NE and how much forcing E there is by the Atlantic trough. This is very finely balanced from 72h though to 144 and we want the Arctic trough to be the stronger force. This will have a major impact on what comes post 144 as it dictates what form blocking will take when the Atlantic attempts to make inroads.

Already GFS is not as good as UKMO 00z in its early stages in this respect (96h) so we would likely need a better Atlantic profile to help out later.

Swings and roundabouts but basically what happens through short mid term is as important as the Atlantic profile post 144.

 

 

[Battleground Snow]

Ukmo 120, next frame could be a boom chart.

It has been the most consistent model by far in the last few days

[mountain shadow]

1 minute ago, Battleground Snow said:

Ukmo 120, next frame could be a boom chart.

It has been the most consistent model by far in the last few days

Very nice

[ICE COLD]

UKMO T144

[Lukesluckybunch]

ukmo 144 fantastic 

[January Snowstorm]

9 minutes ago, Lukesluckybunch said:

ukmo 144 fantastic 

Looks average to me and a considerably less amplified gfs at same point. Let's see where gfs goes

[Neilsouth]

2 minutes ago, Lukesluckybunch said:

ukmo 144 fantastic 

Is it? Looks very slack!