Model Output Discussion - A cold start to Spring?

[Dangerous55019]

Hello everyone. 

Another week has passed, so time for me to have a look at the CFSv2 four weekly anomalies to see what they're showing today... 


Week 1 - 3rd to the 9th March: High pressure over Greenland and low pressure over Scandinavia, with both pressure systems heading up towards the pole... This would leave us in a northerly air flow... I'm kinda guessing snow showers for the majority, but the eastern parts of the UK, being closest to the low pressure would probably have the best chance of seeing more heavy falls of snow.

Week 2 - 10th to the 16th March: The high pressure is moving more towards northern Canada, and the low pressure over Scandinavia is heading more towards Britain! By the looks of the chart, I'm guessing that we would still be in a northerly air flow, but with a greater risk of snow showers.

Week 3 - 17th to the 23rd March: ALL CHANGE! ... The low pressure now appears to be centered just of the south eastern tip of Iceland, plus with high pressure over mainland Europe, this could warm things up a bit by putting us in line for some mild south westerly air... Probably be 'damp'(ish) as well.

Week 4 - 24th to the 30th March: High pressure out in the Atlantic, and also over mainland Europe, and stretching up towards Scandinavia... Although nothing is really showing directly over us here the the UK, I'm gonna hazard a guess that this could put us in line for a southerly air flow... So mild if nothing else.


So there you go folks! Make of that what you will! As always this is the CFSv2, and they are low res charts... So always treat them with caution. 

 

[bluearmy]

1 hour ago, Jacob said:

Absolutley crazy BTFE ensemble from ECM! (won't happen lol)

Is that one eps member out of 51 Jacob ??

[Stuie]

The ICON wants to bring the cold in as a direct Northerly.

[Ali1977]

Icon looks good 
 

 

[Stuie]

Just now, Ali1977 said:

Icon looks good 
 

 

Changed it`s tune from the 6z, firing up that LP.

[Updated_Weather]

ICON12z

Defiantly does seem the Atlantic is more flat. Less progressive and seems to be the 60% chance MetO were going on about in their latest video!

Positive signs!

[Cambrian]

The first weather regimes probabilities extended forecast of the spring emerged yesterday evening. It shows the wall-to-wall Atlantic ridge regime of the first few days waning, and an increasing NAO+ signal, all in keeping with the pressure anomaly charts for weeks 1 and 2.

It’s very easy to appear to be labouring the point about uncertainty in the models, but I just wanted to point out that the Atlantic low makes very little eastward headway between week 1 and 2, the heights to the northwest remain throughout, as does the lower pressure running southward from the Barents Sea through Scandinavia. It has protracted battleground written all over it. Not going to get too hung up on the Atlantic low until we more clearly see the southwestward extent of the cold air by early next week.

  

The NAO+ signal peaks around the 16th of March, and subsequently diminishes in favour of increased blocking, so if the Atlantic isn’t in by then, it will be unlikely that it will get in at all during March. By day 15 on the 0z ECM ensemble mean, the core PV remains on the Siberian side, with low heights still extending down into Northern Europe. Colder uppers are moving back south over the UK and Ireland.

  

A neutral pressure anomaly for Scandinavia heading into the following week suggesting more of a block to the north between Iceland and Greenland, with lower pressure than usual to our south and southwest as the Atlantic low stalls and slowly sinks southeast.

From the ECM extended forecasts then, it’s still looking very much like a cold March, with the notable weather, perhaps very wintry, coming first from the north, a brief chance for the Atlantic, before the cold returns, and a potentially lengthy stalemate ensues. 

The models over the next few days are going to make compelling viewing!

Edited March 3, 2023 by Cambrian

[Mcconnor8]

22 minutes ago, Updated_Weather said:

ICON12z

Defiantly does seem the Atlantic is more flat. Less progressive and seems to be the 60% chance MetO were going on about in their latest video!

Positive signs!

The uppers are much worse for the South for the entire cold spell though and still get the breakdown towards the end of the week, a downgrade in my eyes.

[mushymanrob]

40 minutes ago, Dangerous55019 said:

Hello everyone. 

Another week has passed, so time for me to have a look at the CFSv2 four weekly anomalies to see what they're showing today... 


Week 1 - 3rd to the 9th March: High pressure over Greenland and low pressure over Scandinavia, with both pressure systems heading up towards the pole... This would leave us in a northerly air flow... I'm kinda guessing snow showers for the majority, but the eastern parts of the UK, being closest to the low pressure would probably have the best chance of seeing more heavy falls of snow.

Week 2 - 10th to the 16th March: The high pressure is moving more towards northern Canada, and the low pressure over Scandinavia is heading more towards Britain! By the looks of the chart, I'm guessing that we would still be in a northerly air flow, but with a greater risk of snow showers.

Week 3 - 17th to the 23rd March: ALL CHANGE! ... The low pressure now appears to be centered just of the south eastern tip of Iceland, plus with high pressure over mainland Europe, this could warm things up a bit by putting us in line for some mild south westerly air... Probably be 'damp'(ish) as well.

Week 4 - 24th to the 30th March: High pressure out in the Atlantic, and also over mainland Europe, and stretching up towards Scandinavia... Although nothing is really showing directly over us here the the UK, I'm gonna hazard a guess that this could put us in line for a southerly air flow... So mild if nothing else.


So there you go folks! Make of that what you will! As always this is the CFSv2, and they are low res charts... So always treat them with caution. 

 

As @knocker posted, Anomaly charts without the height contours are pretty useless... or words to that effect. The problem being that you can only see the anomaly and not the upper flow, and they often differ.

To illustrate this, heres the NOAA chart for week 2... The Anomaly (blue dashed lines) do suggest a northerly, but the green 500mb height contours clearly show a mean upper Westerly. The trick is to balance the two, for me the NOAA chart suggests an unsettled Westerly with cold incursions. So there may well be snow showers, but i suspect theyll be "normal" snow showers that we get in PM air in March, mixed with less cold or even briefely milder snaps.

 

[Mucka]

It is a race between the arctic trough coming SW and the Atlantic trough coming E.

If the Arctic trough wins the cold air will force any lows further S.

Here is the 168 marker from the GFS 06z if anyone wants to watch the race.

Edited March 3, 2023 by Mucka

[nick sussex]

I’m liking the GFS 12 hrs run to T72 hrs .

Already that upstream troughing is held further nw .

[Jacob Gamer]

49 minutes ago, bluearmy said:

Is that one eps member out of 51 Jacob ??

I don’t really know what eps is sorry. It is am EMCWF ensemble 

[Battleground Snow]

3 minutes ago, nick sussex said:

I’m liking the GFS 12 hrs run to T72 hrs .

Already that upstream troughing is held further nw .

I'm just getting a bit concerned the greenland high while stronger, is drifting a little too far north west, which will allow the lows to take a slightly more Northern route later on.

[Snowman.]

Just now, Jacob Gamer said:

I don’t really know what eps is sorry. It is am EMCWF ensemble 

Yes

[Stuie]

3 minutes ago, nick sussex said:

I’m liking the GFS 12 hrs run to T72 hrs .

Already that upstream troughing is held further nw .

It`s still wanting to wind up that LP, as does the Icon. Is this going to drag up a SW little ridge quicker?

[Ali1977]

Still plenty of snow showers about Monday night, could be a covering almost anywhere in the U.K. 

[Snowman.]

1 minute ago, Battleground Snow said:

I'm just getting a bit concerned the greenland high while stronger, is drifting a little too far north west, which will allow the lows to take a slightly more Northern route later on.

Important factor here is that the heights in the mid Atlantic beneath the block are more present which will divert the low further south. 

[Mike Poole]

6 minutes ago, Battleground Snow said:

I'm just getting a bit concerned the greenland high while stronger, is drifting a little too far north west, which will allow the lows to take a slightly more Northern route later on.

Yes, compare T102 with 6z T108:

The Greenland high is a bit northwest, but also, the cold from the NE is slightly more advanced.  So difficult to determine the overall effect on the battle zone later…

UKMO quite different T96:

Lows closer, but disrupting well…

Edited March 3, 2023 by Mike Poole

[Stuie]

2 minutes ago, Mike Poole said:

Yes, compare T102 with 6z T108:

The Greenland high is a bit northwest, but also, the cold from the NE is slightly more advanced.  So difficult to determine the overall effect on the battle zone later…

Struggling to see what is going to stop the LP`s ploughing the cold away from the South.

[Ali1977]

Where will it go

i think it’s be epic midlands south again, maybe better than earlier 

Edited March 3, 2023 by Ali1977

[Liam J]

Some amazing charts if you like cold & snow, a memorable March cold spell incoming with plenty of snow chances! 

A very wintry chart from the GFS 12z  

 

 

[Guest]

UKMO 120hrs 12z chart looks like its trending north

[Ali1977]

BOOOOOM , this is a good one

[Guest]

Very disappointing UKMO 144hrs chart for cold/snow hunters:

Edited March 3, 2023 by Guest

[EML Network]

Oh dear ☹ Icon and UKMO 

Might be game over many before its even began