The hunt for cold - Model discussion (late November)

[bluearmy]

8 minutes ago, mulzy said:

A slight change in the NWP with a more southerly tracking jet been shown.  Northern areas *could* get some transient wintriness as Atlantic systems brush against any entrenched cold air.  However the mild and unsettled theme is still the form horse, especially in the medium term.

Day 10 EPS mean suggests an Atlantic influence in the 10-15 day period and this is confirmed by the extended EPS.  A classic winter tale of Atlantic troughing and ridging from southern Iberia into Eastern Europe.

 

Extended eps are more ridgy n of scandi which helps explain the more southerly aspect of the jet - clusters will be worth looking at to see how the mean has been arrived at and if we are approaching a point where two clear directions of travel appear rather than the many we currently have .......still that rise in heights over Europe at day 14/15.  The gems not interested in any absence of euro heights in contrast to the gefs and eps 

[bluearmy]

5 minutes ago, jules216 said:

yes, dreaded Euro high, yet few day ago it was showing a central EU through, this is what I was commenting on yesterday. plenty of blocking to around Scandi and Arctic, but lacking the trigger low

Mulzys chart shows a Euro trough  when you click on it but a ridge if you don’t ..... the trough is correct 

Edited November 29, 2018 by bluearmy

[BlueHedgehog074]

Looking at the likes of the 00Z ECMWF and 00Z GEM, it seems as though more of a West-North-West to East-South-East jet stream could develop for a time later next week. An aspect to encourage Atlantic Low Pressure system’s to our West to dive East into mainland Europe and pull the South-Eastern UK High Pressure back out West. That possible area of cut off heights developing to our North/North-West helping out with this too. 

Something that would put the general mild South-Westerly flow back for its nap. Even if it may only be temporary. Consequently more of a cooler theme for the UK, especially Northern areas. 

Edited November 29, 2018 by DiagonalRedLine

[carinthian]

18 hours ago, carinthian said:

Afternoon all. The resort Advent Path opens later this afternoon ,starts in the village square and ends at the hutte on picture below . Always a popular walk for the children and lasts till Christmas Eve. Thick snow on the ground, frosty night air  and the sweet smell of hot glog in the air , a sure sign of Christmas around the corner. Still no change to the last forecast from over here, charts still have a mild period for Southern Britain , less so for Northern Britain out to 168t , then a rise of pressure around the British Isles in period 168t-240t . During this period a sharpening of the Scandinavian trough becoming a feature. Longer term charts 10-15 days , showing some very low temps over Scandinavia to develop during this period with possible encroachment into NE Britain. Still a long way off but one that keeps occurring in their own model ( possible Arctic high showing its hand with a developing Ac air mass to advect SW  following the low pressure / trough disruption  as mentioned. This would be a rare feature but one that would deliver real cold, however, as always the British Isles will be close enough for the Atlantic to repel. Still lots  of chopping and changing over the next day or so but that Arctic high seems very persistent.

Morning all. super nice start to the day with clear skies and temps just below freezing. Picture of the Advent Path now open till 23rd December. Good agreement in the main models out to 144t. Encouraging chart from GFS ( below ) which shows the early formation of a long wave trough to form to the east during the period 168t-240t. Encouraging because its now in the almost reliable time span which also preludes to the influence of the Arctic high to push the Atlantic lows further south. The forecast upper winds during this period just perfect orientation for this development. Question remains , can we get a Scandinavian high and easterly flow into the British Isles during the period 10 to15  days? I would say yes looking at the charts this morning , this prospect has certainly gained momentum. Will get back with an update from the team over here.

c

[Spanish Dani]

27 minutes ago, mulzy said:

A slight change in the NWP with a more southerly tracking jet been shown.  Northern areas *could* get some transient wintriness as Atlantic systems brush against any entrenched cold air.  However the mild and unsettled theme is still the form horse, especially in the medium term.

Day 10 EPS mean suggests an Atlantic influence in the 10-15 day period and this is confirmed by the extended EPS.  A classic winter tale of Atlantic troughing and ridging from southern Iberia into Eastern Europe.

 

Yes disappointing after reading that there was a lot of hope for December cold.

[daz_4]

18 minutes ago, jules216 said:

yes, dreaded Euro high, yet few day ago it was showing a central EU through, this is what I was commenting on yesterday. plenty of blocking to around Scandi and Arctic, but lacking the trigger low

Through or no through, the first ten days of December will leave much to be desired in central EU. Temps around 10C will be a common occurence I think.

[Johnp]

33 minutes ago, mulzy said:

A slight change in the NWP with a more southerly tracking jet been shown.  Northern areas *could* get some transient wintriness as Atlantic systems brush against any entrenched cold air.  However the mild and unsettled theme is still the form horse, especially in the medium term.

Day 10 EPS mean suggests an Atlantic influence in the 10-15 day period and this is confirmed by the extended EPS.  A classic winter tale of Atlantic troughing and ridging from southern Iberia into Eastern Europe.

 

I think you're looking at a cached chart. As BA mentioned, clicking the chart refreshes it and shows troughing in the med.

[jules216]

18 minutes ago, bluearmy said:

Mulzys chart shows a Euro trough  when you click on it but a ridge if you don’t ..... the trough is correct 

Yes that is the case, but I had a look at EPS up to 360hrs and there is a marked switch from euro low to euro high, I was following EPS every day and up until yesterday it was showing euro through form about 7th to 18th december. now euro through anomaly is there only as a transient feature for a duration of 2 to 3 days. not sure  it will verifiy thgough

[Paul]

30 minutes ago, bluearmy said:

Mulzys chart shows a Euro trough  when you click on it but a ridge if you don’t ..... the trough is correct 

This is why we strongly recommend everyone uses the upload function on the forum, and not just link to images.

[carinthian]

The ECM op at 240t would appear to be out of range of the mean but more importantly has the support of the GFS op. This could be a trend to cold that develops rather quickly !

C

[johnholmes]

Looking at the latest upper air outputs for 6-14 days and there is nothing to suggest any major pattern change in that time scale. The synoptic charts do switch about from one run to another so just beware of anything that does seem conducive to the cold and snow most wish for. Be assured if I see any change being indicated on these charts (6-14 days ahead) I will post them in here.

The notes below are my daily update on the EC-GFS and NOAA outputs

Ec-gfs no signal for deep cold from n or e. What has altered very slightly is that the atlantic flow has veered v v slightly, in the uk/Europe area to be just n of west it seems. This along with the trough over Europe being also a shade more pronounced than a few days ago.

Noaa does not really show either of these on its 6-10 or the 8-14 output

Overall no major pattern change showing; the height values over the uk are somewhat lower on the ec-0gfs but this is quite often the case I have noticed over the years so not sure this is significant.

The flow on the ec-gfs charts is slack in the uk area not Europe. In the slack areas then it is possible for minor ridges to develop but probably only transient I would think. I cannot see how they would be able to develop into any substantial feature to alter the overall upper air pattern.

[booferking]

Cold air sinking snow chances gaining ICON 06z..

[Spanish Dani]

26 minutes ago, carinthian said:

The ECM op at 240t would appear to be out of range of the mean but more importantly has the support of the GFS op. This could be a trend to cold that develops rather quickly !

C

But if you see ridge over Iberia like that then Atlantic would return quickly with milder air for UK.

[Seasonality]

46 minutes ago, daz_4 said:

Through or no through, the first ten days of December will leave much to be desired in central EU. Temps around 10C will be a common occurence I think.

@daz_4 Will be especially annoying after Saturday the 1st of December probably having a -double digit minimum for my location. That said I would say it will probably be even less than 10 days before we see a change to more trough based, and hopefully snowy conditions. I would guesstimate around 8/9th of December for changeover, so still outside of reliable output, but the hints are there.

[northwestsnow]

1 hour ago, bluearmy said:

Mulzys chart shows a Euro trough  when you click on it but a ridge if you don’t ..... the trough is correct 

Thats good news Blue..

[shaky]

29 minutes ago, booferking said:

Cold air sinking snow chances gaining ICON 06z..

Is that low to the south west further south and less deep than the 00z run

[Summer Sun]

The beeb last night mentioned colder in the north and milder in the south for next week and this shows on GFS this morning

Obviously, a lot of caution is needed with these snow depth charts but it would certainly tie in with the colder air over Scotland. Not so sure about the snow heading further into England but you never know if the colder air tracks that bit further south.

[booferking]

That is one hell of a swift in cold air Day 5 compare charts below.

[Tim Bland]

1 hour ago, bluearmy said:

Mulzys chart shows a Euro trough  when you click on it but a ridge if you don’t ..... the trough is correct 

Wow that’s awesome Can you do this for all naff charts this winter please

[shaky]

2 minutes ago, booferking said:

That is one hell of a swift in cold air Day 5 compare charts below.

Someone could get very luky with frontal snowfall on that boundary line!!!what southward push though

[frosty ground]

The shift south introduces the possibility of some snow over higher parts of England 

[Iceaxecrampon]

A bit more life in the output for coldies...!

Decent altitude ppn at 1200ft ASL? 5th Dec.

 

+213 looking promising Scandy LP's  - I'm not posting that one though.

Iain

[Rayth]

Anyone know how often these update or is this a one off Plummet ? I’m presuming below 0 is SSW territory 

 

 

[mountain shadow]

1 minute ago, Raythan said:

Anyone know how often these update or is this a one off Plummet ? I’m presuming below 0 is SSW territory 

 

 

It's the SSW which drives the decline in zonal winds I believe. This forecast chart therefore may in be in response to the warming in the Strat that is being discussed in that thread about the possibility of a rare December warming.

[Mike Poole]

4 minutes ago, Raythan said:

Anyone know how often these update or is this a one off Plummet ? I’m presuming below 0 is SSW territory 

 

 

Daily, based on the 0z GFS, I believe.  Below 0 would be a SSW if it was at 60N, not 65N - you can change the plot, simply change 65 to 60 in the URL.