Interesting how GFS last week struggled to pick up on the dip in 850hpas last week for Tuesday, Wednesday

Last Wednesday's 0z GFS ensembles

Latest 0z ensembles

EC mean looks poor. 

That's actually a really interesting post. We are forever obsessing about forecasting but we rarely hindcast so as to verify the models performance in retrospect. The above just goes to show how changeable the models can be, even within the "reliable" time frame. Admittedly, the operational does seem to have picked up the dip in temperature around the 9th.

Momentum growing now for big pattern change to much colder weather  for the UK as we head towards the last third of the month. Looking at the gph charts on instant weather maps down welling is gathering pace with the 30mb profile looking much, much better. Also even at the end of the run the 10mb profile still looks excelent for high latitude blocking.

With high latitude blocking (-AO) becoming dominant through last third of Jan and well into Feb and the the UK looking ideally placed if the synoptics fall right for us the potential is there for a very long and protracted cold (very cold) spell of weather.

Quite happy this morning with my punt of deep cold arriving by or slightly before 25th.

specific dates given, the trend is the same. Unless I read the MetO long range wrongly at the end of December for 01 to Mid January quote 

“In the New Year there is an increasing likelihood that colder weather may begin to dominate as winds turn easterly. In the north, dry, cold and mostly calm weather is more likely, with frost and fog on many nights and mornings. Wintry showers are quite likely near eastern coasts. Although weather systems may be rather slow-moving and stay out in the Atlantic, where they do push across the UK there will be an increased risk of snow at times. Although signals suggest that a cold spell is the most likely scenario in January, the extent and longevity of the cold weather is uncertain”

was non of that shown in any model output? I won’t quote the December update but I think you get the picture. Anything of note is perpetually postponed, I stand by my comment

GloSea and the European 45 dayer were both pushing our jelly high up to Scandinavia in early to mid Jan. You may still be able to find some Tweets from Met Office folk suggesting it. If you go back a few weeks further there were suggestions of it turning cold in the second half of December. I've got good grounds to think  some Met folk were briefing the media about it.

To my recollection, there hasn't at any time in the last four weeks or so been any consistent suggestion from any of the model output that we are able to view of a protracted cold spell happening either just before/during the festive season or early in January.

The only time we have been at all close to an early winter cold spell which the MetO were suggesting at one point was the brief easterly of sorts we had during the second week of December when pressure rose for a time over Scandi. I think there was a breif suggestion at one point, though bnot with any consistency, that the high over Scandi in mid-December would last for a little longer than turned out to be the case. It was the arrival of Storm Deirdrie on 15th December that really killed off any chance of an early winter cold spell and the fact that HP has been close to the south of the UK or over Iberia ever since then.

6z joins the 300 club.

http://www.wetterzentrale.de/maps/GFSOPEU06_312_1.png 

Pattern beginning to look favourable for some cold

The North Sea low Tuesday is 300 miles further north tracking over north Denmark rather than north Germany as in Friday's models. Northwesterly rather than northerly winds make this far less hazardous in terms of any surge potential

— Chris Fawkes (@_chrisfawkes) January 7, 2019

Then that Greenland high weekens🙄 at 300z

not all about Greenland

Another stunning end to the GFS Para 6z. Still a fully paid up member of the 300h club!

Yep, improving GFS ens too right out in FI, I think this is the week we will see some tasty GFS  FI charts with ECM coming into range this weekend 

GEFS starting to lose the scent? 

https://www.theweatheroutlook.com/twoforecasts/ensemble-forecast.aspx?location=London

if only they could sync up with a cold outlook - one or the other at the moment! hopefully a strong trend will emerge this week on the pattern with heights building splitting the PV and heights remaining and builiding over Scandinavia/Siberia and or Greenland 

I notice the parallel ends more blocked than GFS op run:

Not exactly January 1795 but getting there.

The Met Office will update that as normal as soon as they have updated information which should soon start to mention the possibility of some proper cold conditions developing.

Things can and do change very quickly so as surprise earlier cold shot is not out of the question.

Somewhere between the 18th and the 22nd for lift off. There will be some extremely cold air to the NE by then, so if we get lucky could be a memorable wintry spell.

This would be a great set up for northern blocking and cold. 

You know that those updates are kept quite vague and non-committal until the signals are consistent and strong so it shouldn't be a surprise and nor does it counter the model output, since it's still beyond the range of what we see.

Doesn't the snow row count suggest otherwise?