Model output discussion - 5th December 2016 - Into Winter we go

[Frosty.]

Although the GEFS 12z mean trends generally more unsettled (zonal) from the second half of next week until around Boxing day, high pressure builds from the south between xmas and new year and looks like persisting into 2017 with largely settled conditions across most of the uk with night frosts and fog where skies clear and rather cool bright days but where fog lingers, feeling particularly cold.

Edited December 15, 2016 by Frosty.

[chris55]

John Hammond didn't seem totally committed to a mild Xmas on the six oclock forecast....time for change...must still be some signals of a colder trend pressing in certain areas. And at 10 days thats more than possible.

[Dennis]

Ec12z

[nick sussex]

There are marked differences upstream between the ECM and GFS and so I wouldn't put too much faith in either output until the outputs converge on a solution.

In terms of the overall pattern as a coldie you need to cheer on the ECM, not that its anything to write home about but that we might be able to scrape some interest out of it!

[ribster]

2 minutes ago, nick sussex said:

There are marked differences upstream between the ECM and GFS and so I wouldn't put too much faith in either output until the outputs converge on a solution.

In terms of the overall pattern as a coldie you need to cheer on the ECM, not that its anything to write home about but that we might be able to scrape some interest out of it!

Indeed, quite liking the latter stages of the ECM...

[Stuie]

Agreed Nick, upper`s are nowt to write home about either but better.

[nick sussex]

Just now, ribster said:

Indeed, quite liking the latter stages of the ECM...

I'm doing my best here to find something interesting to say about the outputs! lol Its not easy but the ECM has some scope but in recent weeks whenever its had the better solution that's hit the buffers on the next run. We certainly don't want the GFS verifying, its terrible.

[East_England_Stormchaser91]

Until the usual Canadian and Greenland PV sector blows itself out, I'm going to write December off I'm afraid. January will hopefully see a different outcome. We need to get a real strong block going and frigid robust cold over the continent before we can hope for a real shot of proper winter weather. 

What I can personally foresee however is a possibility of a huge Russian high as we head into January with all of that WAA surging past Svalbard which should help prep up heights over central Russia further down the line. January 2012 was a decent example. It's from then on to see if it has the strength to retrogress westwards. February 2012 was so nearly a snowfest, and even just tapping into the western extremity of the block was enough to send temps down to -16c here. 

Edited December 15, 2016 by East_England_Stormchaser91

[Frosty.]

Fair to say the end of the Ecm 12z doesn't indicate a return to benign anticyclonic weather any time soon after..becomes increasingly unsettled and cold enough for snow on northern hills at times.

Edited December 15, 2016 by Frosty.

[chris55]

Nothing to write home about but i can see where Nick is coming from, some energy finally heading south east, and with a high to the east (even though it not loaded with cold) we can but hope something may progress. Also with the general air mass from the northwest being cool/cold and that PV lobe trending south options are available.

 

[Snow Grain]

1 minute ago, Frosty. said:

Fair to say the end of the Ecm 12z doesn't indicate a return to benign anticyclonic weather any time soon after..becomes increasingly unsettled and cold enough for snow on northern hills at times.

 Not good for coldies.  Have to wait  2/3 weeks for the fun to start.  I must say I am pleased with my forecasting methods as I did forecast this warm December way back in November.

 

Snow Grain replied to phil nw.'s topic in Forecast models, atmosphere, stratosphere & global drivers

I think there is every chance of a warm December, with temperatures well above average. I think the Russian high will play a... 

[Matthew.]

4 minutes ago, Frosty. said:

Fair to say the end of the Ecm 12z doesn't indicate a return to benign anticyclonic weather any time soon after..becomes increasingly unsettled and cold enough for snow on northern hills at times.

Yes that looks the way forward now PM airstream. Well after dark on the 25th i wouldnt say hail/snow showers arent out of the question for some even to lower levels in -5uppers.

[booferking]

1 minute ago, Snow Grain said:

 Not good for coldies.  Have to wait  2/3 weeks for the fun to start.  I must say I am pleased with my forecasting methods as I did forecast this warm December way back in November.

 

Snow Grain replied to phil nw.'s topic in Forecast models, atmosphere, stratosphere & global drivers

I think there is every chance of a warm December, with temperatures well above average. I think the Russian high will play a... 

It would be good to hear your outlook for Jan saying that you got the month of Dec right? Thanks

[nick sussex]

Well the ECM is looking very unsettled and concerns here are these shortwaves running east and deepening quickly at the base of the trough. In terms of any snow chances well further north with some elevation could see something. Also if a shortwave runs east and remains quite a shallow feature rather than blowing up this could spring a surprise.

The upstream differences and uncertainties do impact the earlier timeframe, in particular these northern and southern stream jet interactions, phasing or not and amplitude will effect the T120 to T168hrs timeframe.

In terms of the big 3 the ECM has most scope for a favourable change, the GFS less so.

[Frosty.]

1 minute ago, Matthew Wilson said:

Yes that looks the way forward now PM airstream. Well after dark on the 25th i wouldnt say hail/snow showers arent out of the question for some even to lower levels in -5uppers.

The Ecm 12z certainly shows a full on unsettled / disturbed spell compared to the met office who are still mentioning high pressure influence for the southeast with the main unsettled weather further NW.

[Summer Sun]

Mean pressure drops to around 1015mb for Christmas on the London ens before a steady rise back up towards 1030mb as the year draws to a close

Similar picture on the Aberdeen ens with pressure around 1015mb before a steady rise as we close out the year

The Op is clearly on the more extreme side as we can see by the difference above

 

[blizzard81]

Thank goodness for the ecm run. If the trend on that run continues then the period leading up to New Year and early Jan could get very interesting. To explain a little - the lows are not barrelling through the UK with vigour. The block to the east is a wall. This is not your typical relentless zoneality

[IDO]

ECM up to its old tricks in the latter stages, trying to send the Canadian PV lobe under the block to our east. It assumes the displaced wave from the Azores will be over-powered by the lower heights. Whereas the GFS maintains enough  energy from the higher pressure to our south so preventing that trough to sink over the UK. 

Bearing in mind how relentless the waves from the Atlantic/Azores have been the last 6 weeks I will be a bit surprised if they give up like the ECM predict:

HP -v- LP forcing; normally I would go with the GFS in these situations and looking at the GEFS it is hard to argue with that being the case here. Looking at D10 there are numerous clusters on the GEFS and it looks a tricky setup so maybe neither have the correct solution yet?

[northwestsnow]

Ecm is a million miles better than Gfs - for a start its goodbye euro slug, then we are in the game! 

[Scandinavian High.]

Ten days till Christmas gfs ecm gem all to to Progressive with blowing the block away to east changes to come next few days my gut feeling . Everyone has there own opinions.

[mcweather]

35 minutes ago, nick sussex said:

Well the ECM is looking very unsettled and concerns here are these shortwaves running east and deepening quickly at the base of the trough. In terms of any snow chances well further north with some elevation could see something. Also if a shortwave runs east and remains quite a shallow feature rather than blowing up this could spring a surprise.

The upstream differences and uncertainties do impact the earlier timeframe, in particular these northern and southern stream jet interactions, phasing or not and amplitude will effect the T120 to T168hrs timeframe.

In terms of the big 3 the ECM has most scope for a favourable change, the GFS less so.

As you say Nick the ECM outlook is the best in terms of how one or two tweaks might spice things up a little if the colder pool over Europe is able to advect west slightly quicker that could lead to someone getting a nice surprise come the  big day.  I am reminded to a certain extent of xmas 1993 when out of a seemingly hopeless situation we actually managed to squeeze out a white xmas here in Dorset at an elevation of just 45metres above sea level.  I'll never forget walking home from a lockin at my local in the early hours of Christmas day and realising that what I could feel landing on my bald patch was not rain but snowflakes. Then waking to gently falling flakes on xmas morning with about a centimetre  on the ground. Picturesque but not travel inhibiting, just right.

incidentally that was the last time I actually saw snow falling on xmas day. Although I did have a six inch cover of previously fallen snow in Dec2010.

Edited December 15, 2016 by mcweather

[Polar Maritime]

Just Model Output Discussion please, Thanks. 

[blizzard81]

2 minutes ago, abbie123 said:

Ten days till Christmas gfs ecm gem all to to Progressive with blowing the block away to east changes to come next few days my gut feeling . Everyone has there own opinions.

Well, the ecm has already taken a step in the right direction

[Stuie]

10 minutes ago, Summer Sun said:

Mean pressure drops to around 1015mb for Christmas on the London ens before a steady rise back up towards 1030mb as the year draws to a close

Similar picture on the Aberdeen ens with pressure around 1015mb before a steady rise as we close out the year

The Op is clearly on the more extreme side as we can see by the difference above

 

Summer, tell you what those charts show, complete uncertainty and shows you exactly where FI starts.

[Frosty.]

7 minutes ago, northwestsnow said:

Ecm is a million miles better than Gfs - for a start its goodbye euro slug, then we are in the game! 

Shows how poor winter is when I'm happy to see a chilly westerly zonal flow. Yippee, Ecm 12z rocks!