To be honest, it is best to look furthest only to T144 and T168, as that Model Output currently can still change but the UKMO still has got to show us at T144, so give it a 2-3 more days to continue for Wednesday and early Thursday situation for 31st Jan. to 1st Feb.

The GFS 00z run by far looks very interesting in that the changes to colder weather is showing very well, as early as 96-120 hrs, Cold NW flow followed by a small ridge.

The ECMWF model looks very good indeed but for me not better than GFS if you look at Feb 3-4. 2018, Saturday and Sunday the Low Pressure track over Iceland then sweep east then track SE, looks like GFS I would think.

The High Pressure shown affecting the UK this Sunday to Tuesday still likely to continue, and it looks like a mini Cold spell by Wednesday and early Thursday, but we need support from the UKMO as well, so give it a few more days.

There seem to be NW flows with cold air being pulled in at their rear backs across the UK, that for the SE and South Central UK would bring rain with hill sleet and snow I would think, but with some chance of back end sleet and snow lower ground in Central and N areas as well.

It looks currently possible that GFS and ECMWF are cherry picking some Arctic High and Central N Atlantic High link up as Low Pressure on Feb. 5th to 6th, could cross Greenland then across Central Arctic, with a Norwegian and Finland Pressure rise, SW and Central Europe Low Pressure, created by the Iceland to UK tracking Low from 3rd and 4th February to upto 8th February that could mean a cold spell developing from 4th to 8th Feb. exclusively!, cold ENE winds and Low Pressure over West and Central Europe inc. SW Germany and France as well, dragging cold and wintry weather with freezing cold days and nights and chance of heavy snow showers in the making.

It is advisable to be patience needed as for the main models, the ECMWF and GFS look good at the moment but the UKMO needs to come closer to the said predictions, and at the 240 hr mark it is just a remote possibillity that UK may see cold North and NE winds as that Iceland Low could track across us and NW Europe in general, bring heavy rain and sleet for the Central and SE UK, with sleet and snow showers over NW England N. Ireland and Scotland, by Sunday 4th.

There needs to be at that time Arctic high to extend SW across Svalbard and Norwegian Sea and Norway Scandy et all, say at 240 to 288 hours, that is very much in open to debate, so time will tell!.

And Blocking High over Eastern Canada and Eastern USA is needed as well, including over Nova Scotland and just off SW of Greenland, cold air to be send SW from NE Europe is also required, by West Europe Low.

Oh, and forgot to mention, that we need the West and Mid Central N. Atlantic High to stay in between the NF and Greenland PV Low with WAA pushing agressively NE across our NNW in Arctic, and a decent Block link to Norwegian High P. Ridge that link to Arctic high to our NNE. 

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Originally Posted by: LA2B MeridFlowEuro09 

Still early days but this is probably the best set of ensembles so far IMBY for this latest fantasy crusade!

Originally Posted by: Karl Guille 

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Originally Posted by: Whiteout 

Some very cold runs in there, after so many failed attempts at an Easterly could this be the time, I always feel we need a few attempts before we actually get there, no science there just many years of model watching lol.

The kiss of death (if it gets any further) will be when someone posts a tweet from IF regarding MOGREPS has some probability of an easterly, usually at around day 8.  Wake me up at t72 and I might be interested.

Originally Posted by: Whether Idle 

Well he’s twatted today that Glosea is signalling a Scandy high first week Feb, so I recommend dusting down the BBQ 😂😉

Originally Posted by: nsrobins 

GFS mirrors what P Avery was indicating last night , a cold NEly

Originally Posted by: Gooner 

Direct hit with this one.

Would be my snowiest week for probably 30 years. But at 10 days out I must keep a level head as its all virtual at this stage.

Originally Posted by: hobensotwo 

yes, next run it could well give you your warmest winter week for 30 years😂

need to get some of this output into the 4 to 6 day range and I will be taking note, until then it’s just eye candy 

Originally Posted by: JACKO4EVER 

need to get some of this output into the 4 to 6 day range and I will be taking note, until then it’s just eye candy 

Originally Posted by: JACKO4EVER 

Would it count as a mid winter easterly if it happened and would it reset a modern winter era timescale!!

Originally Posted by: ballamar 

Yup, it's nice to see. Bet it's still not well supported in the ensembles, but you never know...

Originally Posted by: Retron 

It's worth noting that the GFS evolution is rather similar in many ways to that which preceded the 2010 cold spell - which was signalled a long way out (think 10 days+) and eventually came off.

In that instance, the models showed repeated warm advection bursts heading due north, acting in effect as giant waves to mess up the jet stream. Each one made it wobble just a bit more, then bam - an amplified Rossby wave set up and brought most of the UK a remarkable cold spell.

This time around, there's also repeated northwards advection.

The first such attempt has already happened and is in the process of toppling:

There's some rippling of the jet, followed by a northwards burst on day 6: (Note: not due north this time, but enough to draw the Azores High northwards)

That also fails, but the next attempt is an even greater northwards push, on day 10:

This also topples, but in doing so draws a break-away chunk of that upper low SW'wards, which is then trapped. Like a soapy bubble blown across bathwater, the high can't go anywhere else but east - and gives us a textbook Scandi High and easterly setup.

Over on NW, they'd doubtless be going on about wave-breaking and angular momentum pepping up, but you don't need any of that jargon to see what's going on. In effect, it's just like a seesaw with a heavy rock on one end: you push once, nothing happens; push a bit harder and it wobbles, push even harder and the thing flips entirely. And once it flips, it's stuck there for a while!

The key to this is seeing what other models do with that push of heights around 240. GEM doesn't do much (it instead propels it ENE'wards, rather than NNE), whereas ECM this morning had a similar evolution to GFS.

Bear in mind this "push to the north" thing has already started - for once, this isn't entirely pie in the sky stuff, more a case of seeing if the pattern can repeat with increasing amplitude as per ECM/GFS, or whether in the end it all gets shoved away eastwards before it can make the jet kink enough...

Originally Posted by: Retron