Indeed Gavin. Even though no easterly turned up in Jan 2005, a cold easterly spell did develop just after mid-February from what I recall and it actually persisted until almost mid-March. We also got some snowfall during that spell although nothing too major.

In my opinion, the model runs are now looking a little more positive for coldies than they were in the last few days of December. Yes, the eye candy, if it can be called that, is still well into FI but the GFS op runs have been hinting at a change fairly consistently over the last couple of days for later in January. It could all come to nothing in the end but we shall see.

Not much worth adding about the ECM 12z op run, except for the establishment of a weak cut-off high over Svalbard on day 7 that sticks around to day 10, disrupting the Atlantic troughs but not far enough south to do us much good within that range. UKMO is set up in the right way for the same thing going by its day 6 chart. It's a common precursor to some form of high latitude blocking becoming established, but with the strat. vortex on the rebound by this time it probably wouldn't stick around for long.

You see this is what I believe we'll be left clutching at if the MJO doesn't look like doing us a favour within the next 10 days or so.

In light of which, news from a friend of mine that the MJO signal (i.e. strength and progression) in the latest GEFS output is among the strongest in over 2 years is welcome... though as far as I know we still have the issue of the other models not being so keen.

As for as cold weather potential for the UK is concerned, the strat. looks to be backing into the shadows while the MJO comes back into the limelight.

An important NOAA update on the MJO will be released tomorrow, make or break for this month perhaps.

Yes the Met Office have apparently issued a statement saying a major SSW is not expected and the polar vortex will recover later this month. It's unfortunate IMO that the whole 'polar vortex' and strat thing has spiralled out of control on web sites and the print media. Many folks commentating on it are simply sowing the seeds of confusion and clearly don't understand what they are talking about or the physics behind it. 

Anyone got any records on non SSW & polar vortex active cold spells of the past?

18z has been on the sherry and gone for a Greenland/Iceland/scandy high pressure belt, albeit not necessarily in that order

GFS 18z and GFSP 18z at 288.

Surely November 2010! Strat warmings can't occur until the start of December, and we were seeing the signs of deep cold coming even as early as mid month with the atlantic grinding to a halt.

But yes, you don't need strat warmings to get cold, it just helps, and we all knew this SSW was going to be marginal, ofc it still helps even if it is a minor SSW event. There is now a very strong signal indeed for serious disruption to the tropospheric polar vortex by about the 18th. Will we get a cold snap out of it? Probably. Will it be significant? Possibly, nothing to say it won't be, but not so likely.

Feb 1991 was one I believe...

On related but opposite note, the GFS operational is a good example of a strong Greenland/Iceland block that doesn't bring especially wintry conditions to the UK (the south at least) with very ordinary temperatures from 288 to 384 courtesy of Europe being mild and the low pressure to our S and E pulling air from more southerly sources....  Lower temperatures may follow post 384 of course.

Andrew

As the disruption of the PV moves closer, the signal is trending towards a 'temporary' colder shot from around the 17th rather than the more robust HLB as shown by some in recent days, with a renewed northern jet arm again thereafter and towards the end of January. It can all change again of course but that's the situation as of this morning IMO.

The much discussed strat warming has not progressed to either minor or major status, so although the warming per se may influence events, it will not solely be responsible for any sudden appearance of HLB or even HLB where we need it so perhaps that can now be put to bed? I doubt it will be though

The main point for me in this mornings models is a defiant trend towards cold zonality starting from Saturday with increasingly long spells of cold PM air from the NW.

in these cold zonality situations I always use the -5c 850's as a guide to whether it will rain or snow and this line is south of Manchester for much of the ECM run beyond +132 and we could see done significant snow from NW England northwards with some wintry showers further south.

still to early to call as we have been here before only to see more of a TM influence when the time arises.

As for longer term cold prospects then chances look OK but I would put my more on rather cold than very cold for the third week in January.

Andy

Some encouragement from GEFS on the 0h run.ENS split roughly 50:50 cold :mild.Take your pick at 348h from cold members covering UK HP,Scandi,Icealnd ,Greenland and Mid Atlantic.No 3,5,7,8,9 11,16,20.

Worh monitoring the trend now. 2weeks to sit out the dross?

According to what Quantum said last night, strat warmings, while they can be very helpful, are not a pre-requisite for cold winter spells in the UK. As Q said, November 2010 was proof of that, and that occurred before it is even possible for any strat warming to take place.

Even when the jet is strong, it has kinks in it - whether we get cold zonality or mild gunk in such a setup, depends on where the kinks set up - if the jet is on a NW to SE trajectory across the UK, favoured upland regions can still get snow in a predominantly westerly regime - good for the Scottish mountains.

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY MONDAY JANUARY 5TH 2015.

NEXT UPDATE TUESDAY JANUARY 6TH 2015 08:00

THE CURRENT GENERAL SITUATION A warm front will move East across the UK today followed by a cold front moving SE tonight and tomorrow.

MODELS-2 WEEK HEADLINE  Rather changeable and sometimes mild with rain at times and strong winds too. Perhaps becoming quite stormy later and rather colder at times, especially in the North.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows a strong Jet Stream being maintained across or to the South of the UK in the short to mid term before it quickly weakens later as the result of a possible pressure rise to the North and East of the UK later.

GFS OPERATIONAL The GFS operational continues to look very zonal, sometimes mild and wet, sometimes cooler and more showery but never particularly cold but nearly always very windy from a Westerly point. Later in the run though pressure rises sharply to the West and NW slipping East bringing a change to colder and drier weather with some wintry showers in the usual hotspots in the transition period with frosts at night for all then.

THE GFS PARALLEL RUN The Parallel run is similar but makes much less if anything of the rise of pressure at the end to the NW and instead rises pressure close to the South with attendant less chilly and wet weather as a result.

THE GFS CONTROL The GFS control run shows a very lively spell of weather to come with gales and heavy rain never far away from any one place at anytime. There will be spells of cooler and more showery weather with hail, thunder, sleet and snow possible here and there before the model follows the operational's route of drawing High pressure over the UK from the NW later with cold and frosty weather developing as a result.

THE GEFS ENSEMBLES The GFS Ensembles show strong support for a Westerly flow to dominate the UK for much of the period. Strong winds, heavy rain, showers, wintry on hills will be all in the mix before a more open verdict on where we will be in 14 days time is shown with about 20% of outcomes favouring a High pressure block close to the Nort Sea and Denmark at the end of the run with colder versions of unsettled weather elsewhere in the pack than we have currently.

UKMO UKMO shows a strong Westerly flow across the UK over the next 5 days with gales and heavy rain at times. It continues to refuse High pressure being very far away from the South or SW though through the period continuing to dilute the very worst of the stormy conditions towards more Northern areas of the UK rather than all areas.

THE FAX CHARTS The Fax Charts mirror the raw data quite well today showing the end of the week and strart to the weekend with yet another broad mild sector across England and Wales while Scotland and Northern Ireland continue with gales and rain from fronts rushing East in the flow but very slowly South.

GEM GEM today follows the very worn road of late with typical zonal January weather type with Low after Low moving East to the North of the UK with embedded fronts and strong winds delivering rain for all heavy at times especially across the North and West.

NAVGEM NAVGEM also shows a Westerly flow dominant across the UK over the next week or so. Some rain at times is likely for all but with some dry and bright spells at times too, none of which look like lasting very long.

ECM ECM this morning continues to promote Westerly winds across the UK. All areas can expect to see spells of rain and strong winds alternating with colder and more showery periods with a few frosts at night where skies clear and winds fall light enough between systems.

ECM 10 DAY MEAN The ECM 10 Day Mean Chart shows Low pressure to the North and High to the South the most likely scenario at Day 10. The trend towards this has been maintained for a long while now and there is no reason to suggest ECM still hasn't got a real handle on this situation most likely to evolve 10 days from now

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend this morning remains largely usettled and windy with spells of rain at times and short colder spells with showers. Some hints ony late in FI that High pressure might make an appearance over the UK from the NW..

MY THOUGHTS The very Atlantic driven spell of weather is set to continue for a long while yet with all models keen to show their own version of wind and rainy weather mixed with colder and brighter spells with lively showers especially across the West and North where they would be occasionally wintry over the hills. It is left to the far reaches of GFS's output to see any major swing away from this pattern as it's clusters do show a change to rather cooler zonality from the NW or as some grouping also is shown around the possibility of some sort of High pressure forming over or just to the East of the UK in 10 Days or so delivering a period of colder benign weather with the likelihood of frosts for most. Whichever route the models take the clock is ticking on another Winter month that cold lovers will feel bereaved if we still lie in this pattern two weeks from now but for the moment apart from the exceptions logged above the odds are very much still in favour of wet and windy weather far more likely through the middle phase of January rather than cold and snowy. The wait continues.

If you look at the 06GFS ENS there is once again a huge range of solutions from long fetch SW to Scandy highs but the mean (not clusters) still has pressure high over the Azores and low to the North so coupled with the BBC text forecast you have to say that a decent cold spell later in January is no longer 'probable' (as I was corrected the other day LOL) but back to 'slim' IMO.
Days tick by but we are still taking about +300 so lets let a few more tick by.

Not a bad GFSP 06z with more amplification upstream, GFS also has a go but we end up with more of a mid-lat high drifting to Scandinavia.

The 8-10 day charts from both are more positive going forward than the ECM 00z.

As things stand, the odds of colder conditions in some form or other in the second half of January are pretty high, but there's a lot to suggest that this may be of the more settled variety with mid-latitude blocks playing a greater part than high latitude ones.

Weighing it all up, a trough dropping into Europe with toppling mid-Atlantic ridge being able to build to Scandinavia continues to look like the most likely route to scoring any significantly cold, snowy conditions.

In short, what we nearly managed in late December, when the MJO didn't quite do the business and the vortex proved just a bit too strong. Worth noting that there's a significant cold spell ongoing not all that far to our east at the moment (yep - Greece again!), this being what we could have landed had the push from the west been weaker.

Interesting GEFS 6z today. 

http://www.theweatheroutlook.com/twodata/datmdlout.aspx

True. I posted before seeing these. The big mild runs skew the mean up but there is a decent bunch sub -5 and if you scroll through the members there are one or two snow bringers in there.
The fate of January is not decided yet.

looking at the strength of the pv the chances of a greenland block remain remote. Our best chance is for pressure to build in the Scandi/Iceland region. Touch and go on a lot of the ensembles and we need undercutting and shortwaves in the right places. My expectations remain low of a good cold spell

the metoffice removed "chance" of cold from their text forecast about a week ago, yet the chance of settled weather has remained. To me that reads high pressure over the south of uk somewhere.

To me that looks like strong blocking agreement ('warm'/cold south/north) with the sinusoidal behaviour almost dissapearing.