Model Output Discussion - Into Autumn 2019.

[johnholmes]

1 hour ago, johnholmes said:

Apologies about keeping the full post but it seems appropriate.

Interesting post Steve. The situation is not that different from an empirical rule used in UK Met LONG before computers arrived in trying, in winter, to predict when a Scandinavian high could develop. The charts you show are not too different from the ideas behind the empirical rule and the probability of the ridge then persisting for more than 48 hours.

Remember in the 50's and 60's only human forecasts were done so trying to predict beyond 24-48 hours was pretty unusual.

Unable send pm, you do not receive messages!

Anyway here with brief explanation

Hi Steve

Doing this via pm rather than clutter up the model thread.

No luck so far in copying and posting into my pc and thence via pm to you.

I

ps sorry folks some of my text is missing, dinner time so will delete the above and re do it later-sorry

Edited October 1, 2019 by johnholmes

[northwestsnow]

Getting a bit concerned any blocking high is not going to be strong enough and just ends up leaving the already soaking wet UK to suffer more of this horrendous wind and rain.

[Methuselah]

If only it were January, and the T850s were 15C lower!!!

   

 

[I remember Atlantic 252]

15 minutes ago, Ed Stone said:

If only it were January, and the T850s were 15C lower!!!

   

 

this would do, great childhood snowy days

[Methuselah]

But, alas, the GFS Operational is all on its lonesome, regarding that intense depression on Day 16!

   

   

And, if those Average 2m Temps are anything to go by, 'same sheet, different day' would sum-up the 12Zs quite nicely!

[Frosty.]

I noticed quite a bit of Arctic potential lining up for just after mid october on the GEFS 12z...I wouldn't rule out some surprisingly early snow this month!❄

[tinybill]

i see  thr  gfs  have Lorenzo  going from wales via the heart  of the country  ex  s e of the  uk

[damianslaw]

Current synoptics and those forecast for the rest of the week, in the depths of winter would bring a snow/freeze fest - classic synoptics for snow in winter.. alas its the 1 October, but an unusual pattern none the less, low heights coming unstuck against a block to the north, a front moving north then back south.. followed by a cold ridge and then an undercutting low pressure sliding through the UK with scandi heights..

Its good to see some more interesting synoptics than the usual default atlantic SW feed.

[Don]

1 hour ago, JON SNOW said:

I noticed quite a bit of Arctic potential lining up for just after mid october on the GEFS 12z...I wouldn't rule out some surprisingly early snow this month!❄

An October 2008 repeat would satisfy me!  We can all hope.

[Frosty.]

I wouldn't mind seeing more charts like this as we head towards winter..nice!!!!❄

[Newberryone]

Unsurprisingly the lack of posts in here so far today would seem to reflect the latest output from the 00z Ecm. Very different from yesterday’s 12z, not of course with regards to Lorenzo but with regards to what follows.Yesterdays output had a much stronger looking jet stream suppressing any heights to the south whereas it’s the opposite today. So as it stands next week and quite possibly beyond looking very benign indeed with little sign if any of anything remotely wintry.

Edited October 2, 2019 by Newberryone

[ItNeverSnowsInWindsor]

Looks like pretty average temperature wise with no heat plumes likely either.

 

[MATTWOLVES 3]

24 minutes ago, Newberryone said:

Unsurprisingly the lack of posts in here so far today would seem to reflect the latest output from the 00z Ecm. Very different from yesterday’s 12z, not of course with regards to Lorenzo but with regards to what follows.Yesterdays output had a much stronger looking jet stream suppressing any heights to the south whereas it’s the opposite today. So as it stands next week and quite possibly beyond looking very benign indeed with little sign if any of anything remotely wintry.

I've got to agree with you here. Nothing in the extended ECM ensembles that show anything to cold. It still looks like a build of pressure around mid month with some settled conditions, and average temperatures... Obviously cool nights could be expected. In all honesty I fail to see how a significant cold spell in October could be a Signal for a cold winter ahead! You only have to cast your mind back to the big freeze of December 2010,to see that an early severe cold spell can quickly be replaced with a benign spell for the rest of the Winter! 

[ItNeverSnowsInWindsor]

Thankfully there’s nothing warm showing up on GFS 6z following on from the overnight run. The stand-off between ECM and GFS continues.

[mb018538]

Lots of spread on the ECM ensembles, even at day 6 there is a 15mb pressure difference between the top and bottom ensemble members. It did look like something a bit more settled might start to creep in, but that now seems to be no more or less likely than unsettled weather continuing. I can understand the lack of posts, it's a pretty uninspiring outlook at present. 

[booferking]

Early Days but signs are there for something of cool down.

[MATTWOLVES 3]

Tonight so far we have a full house at day 6....Namely deep low pressure to our NW.... Meaning spells of rain and showers, on at times quite gusty winds!! The far NW looking quite dire. UKMO, GFS, ICON and GEM all singing from the same sheet at day 6. Pretty mundane stuff if you ask me... 

[SMU]

^^ Indeed the important part of the interaction of the deep low in the atlantic & block to the NE ~144 is that the jet energy is still inclined NW > SE ... So a slightly milder more mobile pattern reflected in the midterm- however with residual heights located over the pole there is a higher probability of a cold outbreak post day 8/9 than there is a draw from the south....

NB ECM performance been very poor of late - very progressive...

 

Edited October 2, 2019 by Steve Murr

[Kirkcaldy Weather]

7 minutes ago, Steve Murr said:

^^ Indeed the important part of the interaction of the deep low in the atlantic & block to the NE ~144 is that the jet energy is still inclined NW > SE ... So a slightly milder more mobile pattern reflected in the midterm- however with residual heights located over the pole there is a higher probability of a cold outbreak post day 8/9 than there is a draw from the south....

NB ECM performance been very poor of late - very progressive...

 

Certainly some interesting charts being churned out by the ensembles...

           

[booferking]

Gem showing interest also.

[Mair Snaw]

17 minutes ago, Kirkcaldy Weather said:

Certainly some interesting charts being churned out by the ensembles...

           

Imagine those charts spilling out in late December to Mid January??  i dare say some would still no be happy.

[MATTWOLVES 3]

12 minutes ago, bigsnow said:

Imagine those charts spilling out in late December to Mid January??  i dare say some would still no be happy.

I would say folks would be even less happy if those charts aren't being spilled out come then! 

[Tamara]

Just as a very brief addition (before properly retiring to the sidlelines until next Spring) to the previous post made about 5 weeks back which alluded to the escalation of confirmation bias wrt weather preferences which.rises to its highest levels in autumn and winter

Its based on a conversation I have had with someone who is a very well respected observer elsewhere, with a level  of knowledge and perception that many would aspire to and of a higher technical level for sure than my own. Most importantly they suspend their own natural preferences and make judgements neutrally and based on the merits of all variables present and not selectively.  Such observers I think are the ones particularly worth listening to and trying to learn from.

Anyway, relevant to the here and now situation but extrapolating that forward in terms of future possibilities  - here is some of that conversation based on my own contributions. A few further additions have subsequently been made to make it most relevant to the UK and Europe

 

Yes for my own purposes, a defacto traditional Nina regime looks increasingly likely to persist in the months ahead. The question being where any Pacific convergence may set up to interfere with the regime and create scope for less tropical and extra tropical disconnect to the base state. In that sense the much less disconnected SOI plays a bit part if any westerly wind compartment is isolated, so to speak, due to a wider overriding -ve momentum inertia

High amplitude Phase 3 GWO could well be set to return to Phase 1 as trade winds increase across the IO following the recent extra tropical increase in momentum. Once the +EAMT wavelength fades over coming days, -ve FT in the tropics will lead MT momentum trending -ve once more and maintain the GWO well within the Nina attractor phases - providing the steer to persisting sub tropical ridging. This sub tropical ridging is well in evidence in present modelling and amplification of this ridging during autumn and indeed winter to provide short lived colder incursions is quite consistent with many similar years and not at all unusual, or any signal of a harsh winter,

This, plus question marks wrt QBO transition needs to be balanced against any weakness within the polar field c/o arctic and other destabilizing factors and why I personally continue to be much more ambivalent and sceptical about the relevance of blocking patterns at this stage of autumn in terms of what it might imply ahead. 

Just my view of course - and which customarily tries to be detached from mainstream hype that grows each and every year, at this time of year - and when sensible weather preferences and ideals often attempt to fit too many drivers to produce that desired outcome, when probabilities often suggest alternative solutions that are much less popular to the masses. 

The gist of this extract is that much is yet to become clearer in terms of seasonal overview, but especially stressing that model output commentary during the early stages of the short seasons and making assumptions  based on persistence of certain aspects of patterns is fraught with error when attempting to assign specially selected drivers as a means to fit the desired outcome. 

To all those following progress of the weather patterns in the weeks ahead, try to enjoy progress and evolution - regardless of outcomes vs preferred outcomes

 

 

[MATTWOLVES 3]

Was going to replie to David... Mr frosts post, but appears to have gone missing! The ECM op was a little severe with the fall in pressure, and also with the temperatures. Low pressure looks more focused to the North on the mean, and subtle signs of an increase in pressure to the South towards the end!! All along way off though. 

[Mr Frost]

8 minutes ago, Mattwolves said:

Was going to replie to David... Mr frosts post, but appears to have gone missing! The ECM op was a little severe with the fall in pressure, and also with the temperatures. Low pressure looks more focused to the North on the mean, and subtle signs of an increase in pressure to the South towards the end!! All along way off though. 

Knew I should have left out the chat of previous severe Winters! 

ECM 144 to 240

@Mattwolves great post above - that sounds a much better outlook than the op. Let’s hope you are spot on.