Model output discussion - here comes the beast!

[Frank Trough]

7 minutes ago, bluearmy said:

If you can guarantee that uppers won’t get above zero and surface flow will remain se then it can get as close as it likes! However, it’s the ultimate ‘high risk = high reward ‘ on this upcoming pattern and if we get it to run up the channel and pull the deep cold back in behind then as long as it doesn’t rejig the neg NAO too far west it’s the best evolution !

Living in Bomo I'm going to say "take the risk"! I think it's the best chance we'll get of significant snow - showers don't necessarily cut it for our area in an easterly.

 

Is it 1978 that this remind me a bit of? 

[Altostratus]

Another excellent GFS run there and very reflective of the ensemble mean earlier. Epic blizzard being shown at the end of the reliable time frame -that would rival the greats of yesteryear.

[Duane S.]

3 minutes ago, Certain kind of fool said:

Living in Bomo I'm going to say "take the risk"! I think it's the best chance we'll get of significant snow - showers don't necessarily cut it for our area in an easterly.

 

Is it 1978 that this remind me a bit of? 

Yep, this is the one we want...

1978 all over again.

High(er) risk (very) high reward.

How I wish we could bank these charts up to +168.

[Steady Easterly]

Many parts in the East especially, but also other areas, would be cut off if this output is anywhere near correct, quite incredible charts. Model watching will never be quite the same again after all this.

[joggs]

Imagine if there was to be a humongous flip in the next 48 hrs or so lol.

I think it would be the biggest epic fail of all time.

Anyway gfs 6z carrying on the slight upgrades for me on that run.

I just wonder with it trying to bring in the low,sw of us next week if it's up to its normal trick of trying to get the Atlantic back in quicker.

Anyway,a blend of the ecm and ukmo runs this morning would suit me.

Been a long,sapping week but great model watching.

We'll all sleep through the snow next week lol.

Edited February 22, 2018 by joggs

[terrier]

Cracking gfs06z certainly upgrades the cold and snow potential next week. Think we will definitely be seeing sight like this next week 

[Snowbound]

Brand new post for me, having been an avid watcher for a while now. I have a couple of questions regarding the output showing for next Tuesday/Wednesday. Where I hear

deeply unstable easterly feed being mentioned, and showers convecting up as the bitter cold crosses the north sea to deliver snow showers to the UK.  In this scenario, the 

air that rises over the sea, which creates the shower clouds, in the air, in the act of rising upwards  and creating convective clouds does this not introduce warmer or less cold

air from below, and my question resulting from that, is,.. Is that why the uppers over the UK are lower than Europe slightly due to the air aloft being modified by convective up-draughts ?

Or Does the depth of cold negate that, and if so does that not lead to a collapse of any convection.. Over time would an endless easterly driven series of disturbances lead to the bitter cold

being modified some what or does that only occur if the airflow becomes slacker.. Apologies for the in-depth question.. Im curious about this.. I also saw John Homes mention about the origin

of the isobars and we want the isobars  downwind to originate from far to the east. On the latest GFS6z although we have cold south easterlies over us on 1st March, the isobars can be traced back 

to the Balearic islands.  Is this important? then or day or so later?  

 

Thank you for reading and replies. I love model watching and i am fascinated by the intricacies as well as the fluctuating outputs.

 

Bob

[mrmonopoly]

in this type of setup us in the west need the adlantic to move in enough , stuff coming from east generally doesnt get to here just very cold and dry

[swfc]

Way out on fi but we head for pne final snow storm at 336 hrs. Epic run

[Midlands Ice Age]

35 minutes ago, SizzlingHeat said:

The low in the Azores is concerning for prolonging the cold. Looks to make inroads towards tail end of the week again....

SH...

Or as suggested it could help to prolong the bitter cold if it elongates (disrupts)  to the south of the UK. 

If it does this over the Channel we could well be seeing huge amounts of snowfall for England. 

Could well begin to rival some epic snowfalls of the past.

 In fact the latest charts begin to show just that. 

MIA

[bluearmy]

Eps clusters - 2 left (20% + 10%) which are towards the poorer cluster from past couple days with a sunken upper ridge closer to our west and less instability in the e flow 

for you non mathematicians out there that’s 80% saying YES !

anyway, the op trend to bring the upper Azores low up from the sw is 40% with the ‘safer’ cluster  - 60%. The op cluster looks a bit too close for comfort on the upper s flow getting too far north - let’s see how this evolves on the next suite and the gefs, seeing as they were playing with it on the 00z run

[Duane S.]

2 minutes ago, mrmonopoly said:

in this type of setup us in the west need the adlantic to move in enough , stuff coming from east generally doesnt get to here just very cold and dry

Yes a system moving up from the SW, up against embedded cold air is indeed nirvana but beforehand there will be plenty of disturbances in the flow to bring very decent snowfall totals, even in the west.

[iowpompeylee]

4 minutes ago, Midlands Ice Age said:

SH...

Or as suggested it could help to prolong the bitter cold if it elongates (disrupts)  to the south of the UK. 

If it does this over the Channel we could well be seeing huge amounts of snowfall for England. 

Could well begin to rival some epic snowfalls of the past.

 In fact the latest charts begin to show just that. 

MIA

I was just thinking that, surely if the low near the Azores was to creep up near the channel we would get copious amounts of snow from it.? Excellent model viewing atm. Has there ever been a more exciting time??? 

Edited February 22, 2018 by iowpompeylee

[mrmonopoly]

1 minute ago, s4lancia said:

Yes a system moving up from the SW, up against embedded cold air is indeed nirvana but beforehand there will be plenty of disturbances in the flow to bring very decent snowfall totals, even in the west.

I am just trying to understand bluearmy post , is what he is describing exactly what we are hoping for from the SW

[bobbydog]

you don't often see snow charts like this for the 2nd march-

"its Spring Jim, but not as we know it"

[bluearmy]

not taking much from deep fi gfs in a reverse zonal correcting back to zonal atmospheric environment - however, it does present a new idea which is when the westerlies recover themselves somewhat as the neg NAO subsides, we could have a residual decent ‘wedge’ meandering east which could help to prolong the cold spell and take us to a slidergate scenario approaching mid March 

[Connor Bailey Degnan]

Arpege 6z looks not perfect, but a good deal better than its 0z output. 

[stodge]

Morning all

Was it a case of "Wobbly Wednesday" yesterday as one or two people over-reacted to marginal movements in the models ?

It's worth repeating one more time - IF the HP is too far north it might be a lot of snowy fun for some but it would be short-lived snowy fun with the snow falling on Tuesday and melting by Saturday as milder air comes up from the south.

The very cold pool is unstable and creating disturbances and LP features which, while good for snow fans, cuts off the cold flow from the east and north.

Having the HP further south provides greater insurance the cold will remain locked in with the jet far to the south and with successful retrogression a re-load from the NE in time.

So let's see where we are this morning with the medium term output taking us to Sunday March 4th and starting as always with ECM 00Z OP:

A very cold and snowy chart. The LP has moved up from Iberia and has become slow moving across SW England but 850s are -4 to -7 across the British Isles so probably snow for most and especially further north and on higher ground. The hope for cold fans is the LP sliding away SE into Europe and returning a cold NE'ly flow. Note also renewed rising heights over Scandinavia.

GEM 00Z OP at T+240:

Another very cold and snowy chart from a model which has played the cold card strongly throughout the evolution. The Greenland HP ridges SE almost to the Azores holding the jet a very long way south. 850s are below -8 over much of England and there's an actual lobe of vortex with uppers of -20 over Germany which you don't see every day or indeed any day. A slack NNW'ly airflow brings in heavy snow showers to eastern and northern areas with a deepening LP off the east coast of Scotland set to augment that activity as it runs SW.

GFS 00Z OP at T+240:

Something very different. An E'ly flow across the south but with HP to the north centred across Shetland and linking back to heights over Greenland and ridging over Scandinavia and the Baltic. It's still cold with -8 uppers over most of the British Isles but it's going to be dry and hopefully sunny but with severe frosts. Further into FI and a series of shortwaves break down the HP and a westerly flow resumes bringing much milder air back across the British Isles.

GFS 00Z Control at T+240:

The cold spell is over and mush milder air has already returned back across the British Isles with LP to the west and south west taking over and bringing in unsettled conditions with rain and showers and a rapid thaw of any snow. Further into FI and the cold air makes a return to northern areas with the possibility of a new HP setting up just to the north of Scotland and an E'ly flow returning but still mild in the south for the time being.

GFS 06Z OP at T+234:

Again, the cold spell is over with a SE'ly flow as LP in the mid-Atlantic takes over and brings rain or showers in from the SW. Further into FI and the British Isles becomes the battleground between the warmer and colder air-masses so northern and eastern areas remain cold and wintry with southern and western areas much milder and of course the potential for severe snowy events across the middle of the country.

The GEFS for 00z at T+240:

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

A growing cluster, it has to be said, of milder options creeping in to the suite but plenty continuing the cold.

In summary, GEM and ECM are excellent for cold weather fans but the GFS is a worry and an increasing worry. Yes, it might be over-progressive but it does seem keen to want to re-introduce milder air from the south west and bring the jet back north which the other models don't so it's a stand off and it may be as the UKMO forecast suggests, the south and west will become milder while the north and east stay cold and a battleground develops into March between the competing air-masses.

[johnholmes]

17 minutes ago, Snowbound said:

Brand new post for me, having been an avid watcher for a while now. I have a couple of questions regarding the output showing for next Tuesday/Wednesday. Where I hear

deeply unstable easterly feed being mentioned, and showers convecting up as the bitter cold crosses the north sea to deliver snow showers to the UK.  In this scenario, the 

air that rises over the sea, which creates the shower clouds, in the air, in the act of rising upwards  and creating convective clouds does this not introduce warmer or less cold

air from below, and my question resulting from that, is,.. Is that why the uppers over the UK are lower than Europe slightly due to the air aloft being modified by convective up-draughts ?

Or Does the depth of cold negate that, and if so does that not lead to a collapse of any convection.. Over time would an endless easterly driven series of disturbances lead to the bitter cold

being modified some what or does that only occur if the airflow becomes slacker.. Apologies for the in-depth question.. Im curious about this.. I also saw John Homes mention about the origin

of the isobars and we want the isobars  downwind to originate from far to the east. On the latest GFS6z although we have cold south easterlies over us on 1st March, the isobars can be traced back 

to the Balearic islands.  Is this important? then or day or so later?  

 

Thank you for reading and replies. I love model watching and i am fascinated by the intricacies as well as the fluctuating outputs.

 

Bob

Re the tracing the isobars back.

If they originate from the Med then they will bring less cold, even milder surface air. However, that air will be brought over what may well be a snow covered countryside in Europe so that again would modify it from the Med. But when it reaches the UK it would be nothing like as cold as the air from northern Europe. That is the surface air or no more than the lowest 3-5000ft. Air above it would mostly remain with its Med characteristics.

Hope that makes sense.

Best you pm me if that is available to you to save diverting comments on the model thread from this post. thanks

 

[Man With Beard]

9 minutes ago, bluearmy said:

Eps clusters - 2 left (20% + 10%) which are towards the poorer cluster from past couple days with a sunken upper ridge closer to our west and less instability in the e flow 

for you non mathematicians out there that’s 80% saying YES !

anyway, the op trend to bring the upper Azores low up from the sw is 40% with the ‘safer’ cluster  - 60%. The op cluster looks a bit too close for comfort on the upper s flow getting too far north - let’s see how this evolves on the next suite and the gefs, seeing as they were playing with it on the 00z run

Thanks BA (though surely 100% - 20% - 10% = 70%?!?!?)

To add the charts D6, D7 and D8:

    

On clusters 1, 2 and 4 we are, as you'd say in poker, "all in". Out of the "poorer" clusters (an incredibly relative term of course), on cluster 3 most of England still gets the full force of the cold pool by D7, and on cluster 5 it just brushes the south-east - but cluster 5 has just 5 members, and I cannot recall a single time when an ensemble member that small has verified against the majority at D6 - so it's nearly possible to discount this cluster.

BA has summed up the D8-D10 clusters well - but just to add my own take - I can't see how we can escape a widespread snowfall on either of them.

[phil nw.]

Looking very interesting towards the end of next week with that developing mid-atlantic trough heading east towards Europe under the block.

the ecm had the same idea

this would produce an elongated frontal zone running west to east around the channel/N.France trying to move north against the cold block over the UK.

We could see a tremendous battleground snow event across us from this with such a large temperature difference across the boundary layers.

Quite a feasible evolution as the block to the north starts to drift further west.This is the point where our expected severe cold spell comes under attack.

Looking at the day 10 mean charts the cold may well hang on a while longer -this possibly more likely on the ecm with it's deeper cold upper trough.

The polar vortex now pushed completely over  to the Siberian side by this time remains our source of cold from the NE with the mean jet still running to our south.Without the strong influence of the block though we look like relying on a cold Scandi trough to gently feed the cold this way and with all the cyclonic activity there will inevitably be some modification of the upper cold. 

The next stage is whether the block moving away will retain enough influence to keep us on the north side of the cold Atlantic/Euro trough after days 9/10 as the warmth from the south tries to push north.

Certainly looking bitter next week and now with increasing chances of quite widespread snow especially later in the week if that push from the south verifies.

[karyo]

6 minutes ago, Connor Bailey Degnan said:

Arpege 6z looks not perfect, but a good deal better than its 0z output. 

Yes, even the Aprege is looking better this morning. The other models are looking great and they have all upgraded from yesterday! 

I am trying not to get carried away but confidence is increasing on a very potent and hopefully long cold spell. 

 

[swebby]

27 minutes ago, joggs said:

Imagine if there was to be a humongous flip in the next 48 hrs or so lol.

I think it would be the biggest epic fail of all time.

Anyway gfs 6z carrying on the slight upgrades for me on that run.

I just wonder with it trying to bring in the low,sw of us next week if it's up to its normal trick of trying to get the Atlantic back in quicker.

Anyway,a blend of the ecm and ukmo runs this morning would suit me.

Been a long,sapping week but great model watching.

We'll all sleep through the snow next week lol.

Eeekkkk!  Your a brave soul Joggs?!?!  Proper cold is still only arriving @t96 on the charts and that's certainly not new territory for model let downs.  When we get to Sunday and the cold signal is @ t12 and looks locked in for a fortnight, then by all means tempt fate.

[stodge]

To add to my previous, a superb UKMO 00Z run for those wanting a prolonged cold spell:

The tilt of the cold airflow to the west of the British Isles holds the Atlantic systems well at bay over the Azores and points further SW. If anything, the storm to the far north of Scandinavia is doing us a huge favour keeping the HP further south and accentuating the E'ly flow.

-12 uppers widely across the country by next Wednesday so that suggests an ice day or close to it even in London though the urban heat island might just get above freezing even next Wednesday.

[karyo]

1 minute ago, swebby said:

Eeekkkk!  Your a brave soul Joggs?!?!  Proper cold is still only arriving @t96 on the charts and that's certainly not new territory for model let downs.  When we get to Sunday and the cold signal is @ t12 and looks locked in for a fortnight, then by all means tempt fate.

Yes, it will be dreamy if the charts look close to this by Sunday. Then we can start looking at precipitation charts with confidence..Been burnt too many times!