Model Output Discussion - Spring Has Sprung

[Mike Poole]

 bluearmy According to ECM, on the cluster plot:

• a red frame indicates association with the blocking climatological scenario,
• a blue frame indicates association with the positive NAO climatological scenario,
• a green frame indicates association with negative NAO climatological scenario,
• a violet frame indicates association with the Atlantic ridge  climatological scenario.

The same colours are used on the 46 dayer regimes plot, where they are described as follows:

• Blue - positive North Atlantic Oscillation (NAO+).
• Green - negative North Atlantic Oscillation (NAO-).
• Red - Scandinavian Blocking (BL).
• Purple - Atlantic Ridge (ATR).
• Grey - members with no regime attribution

Assuming the regimes are the same or close, then I think it is right to interpret red as Scandi block, but obviously each regime covers quite a wide range of possibilities, and sometimes the plot doesn’t obviously look like the regime it has been assigned by the algorithm!  

In fact, one could simplistically interpret the regimes as: blue - high to the south, green - high to the north, purple - high to the west, red - high to the east.  And that wouldn’t be far wrong.

Edited February 3 by Mike Poole

[ANYWEATHER]

A very messy outlook, snow perhaps for a few ,rain for many.  Can't see any exciting cold charts to be honest, would like the ecm to verify at day ten ,with high pressure over the uk, with frosts and sunshine by day......

[damianslaw]

I'm certainly keeping very open minded where the track of the low pressure ends up at this range, over 5 days away... expects plenty more model variance in days ahead in this respect. meaning reliable is very short timescale. 

[Anthony Burden]

 bluearmy Hi yes as ECM operation shows that progression and as you say the most likely.

[Singularity]

The low crossing next Thu-Sun is a transitional event, occurring as the pattern shift starts. Still far enough ahead in time for substantial path revisions but probably a long shot for southern UK from a settling s snow perspective.

After that, we have a strong signal for a highly blocked pattern with sluggish polar jet. Meanwhile, the polar vortex looks to be under assault again, limiting its ability to force a +AO.

So the stage will be set for 2nd half Feb to be characterised by a classic Scandinavian to Greenland high sequence. As ever, the finer details will determine how much the UK is affected by resulting cold air masses & snow events.

[feb1991blizzard]

GFS looks like it will start its usual micro staged move on this run.

[Ali1977]

Subtle shift north on the first bit of precip 

[Ali1977]

Good for the north by Thursday, possibly colder on the back edge for the south by Saturday again 

[Ice Day]

That's quite a range of 850's over the UK by next Thursday according to the GFS 6z, 4c on the south coast down to -8 for northern Scotland.

And a lot of snow around for those in the sweet spot

The track of these lows is far from nailed though, further shifts north or south are 100% certain.  

 

[CoventryWeather]

Agreed no model consistency. Models don't have a clue...

 

 

[Lukesluckybunch]

Lovely stuff at 156 in the gfs!

[nick sussex]

 Ali1977

Problem is it’s already started backtracking .

You wouldn’t want to put money on even this run verifying . The GFS tends to shift slowly so that it hopes people don’t notice !

We’ll see what the Euros do this evening .

 

[IDO]

The 06z is a big downgrade for snow south of the M62, and not really what we want:

06z:  0z: 

[MJB]

 IDO At this range its more of another variation than a downgrade IMO

[Lukesluckybunch]

There's just too much pressure on the pattern to push it further north...I'm really not sure where we go beyond day 7..but it doesn't look good!

[Ali1977]

 nick sussex not are it’s a backtrack , just a different position of the low - the 850s actually go colder quicker than the 00z of the back of the initial low. Hopefully the ENS upgrade the snow chances - but knowing our luck it will backtrack as we move closer!! 

[Ice Day]

2 minutes ago, nick sussex said:

You wouldn’t want to put money on even this run verifying .

Absolutely Nick.  I'd be extremely cautious over any run outside 72 hours at the moment.  This particular setup is very complex and the systems being delayed by, or coming through 6 hours faster than modelled will have significant consequences on the ground.  

 

[Harsh Climate]

 Lukesluckybunch

Gfs 6z Op doesn't mean anything until we see essembles, worthless in its own right good or bad.

Edited February 3 by Harsh Climate

[Kasim Awan]

Increasing chance now that the initial easterly and snow producing front will be confined to Northern areas due to the effects of a fairly stubborn Iberian high early on which causes more of a dartboard low which spreads the front out further North.

[Lukesluckybunch]

Really looking flat at day 8..thought maybe that shortwave over Iceland could drop down,and reignite the cold..

[IDO]

 MJB

It has moved towards the GEM which was poor. The GFS op was the main hope for a snowy period.

GEM:  GFS 06z: 

[Lukesluckybunch]

1 minute ago, IDO said:

It has moved towards the GEM which was poor. The GFS op was the main hope for a snowy period.

Absolute chaos upstream...good luck with getting anything prolonged out of that setup!

[Kasim Awan]

Another dry but cold type spell is on the cards now. Front goes North and dry Northerly followed by a dry high pressure etc looks very possible at present.

[Chesil View]

 MJB indeed at 5 or 6 days out the complexity of the angle and timing of the arrival of the airmasses means a lot more variation will appear right down  to T24. 

The envelope will narrow but still with variation on the actual outcome.

[Ali1977]

Liking that little cut off high firming in the North Atlantic - hopefully migrate north