Model Output Discussion - Into Autumn 2019.

[Methuselah]

The GFS 00Z Operational is again running along the coldest end of the ensembles, this morning, so is, IMO, hardly representative of the likely evolution; it is, though, often the case that temperatures fall-off during October, so such an outcome wouldn't exactly be all that surprising!

   

   

The countdown to Building Blocks Time is almost upon us!

[Summer Sun]

Next week starts quite chilly with winds from the north but the ex hurricane will soon sort it out bringing a change to milder air as well as further heavy rain and strong winds

[summer blizzard]

0z GFS between days 10 and 15 must be one of the coolest and wettest periods that could be modelled. Cyclonic (so probably wet) but with sub zero uppers.

No doubt some golden -AO values too.

[johnholmes]

Thursday 26 September 2019

Certainly some changes and differences between the models by today.

Ec has dropped any ridging/+ve heights and now shows a strong atlantic flow from usa into uk, although less strong in nw of uk where previous charts still showed some linkage to Greenland heights. Gfs has a stron atlantic flow but keeps more of a link to Greenland ridging over n’ern half of uk

Noaa shows a trough in atlantic that dips south giving a s of w flow into the uk of less strength than ec, again less again in nw with some +ve heights shown from Europe across uk towards Greenland; but small.

Overall the upper pattern shown suggests changeable rather than settled, and of course shows no inclination on mean charts of the effects of any hurricane/tropical storms in the north atlantic. Any settled periods being less frequent in the 6-10 period than unsettled/changeable days. The contours suggest surface temperatures being likely to range from about average/touch below at times in the north to average/touch above at times in the south. Always the possibility of gales for more nw’ern parts with the contour pattern shown even without any tropical input.

https://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

[Frosty.]

4 hours ago, prolongedSnowLover said:

It’s looking increasingly cool and unsettled according to latest GEFS run 0z.

Perhaps a good sign for proper winter ?

My opinion of the mean is that longer term it indicates a N/S split with the most unsettled weather further north and temperatures generally around average but a tad below further north..pretty average normal october conditions...and as far as winter is concerned, this means nothing!

Edited September 26, 2019 by JON SNOW

[Methuselah]

This should be just enough to ensure that September's CET won't fall from what it is now? Barring any downward adjustment, of course!

   

[mb018538]

Now that Lorenzo is starting to be better modelled, it appears it will inject too much energy into the jet and keep things unsettled for now:



Still roughly 1/3 of members going for more settled weather a bit later on, but the form horse is unsettled and zonal to continue:

[Methuselah]

Defo looks as if a cooler, rather than a warmer outlook is starting to take hold, now -- there are fewer warm 'options' within the ensembles, now, than has been the case in recent days...?

   

   

[shaky]

23 minutes ago, Ed Stone said:

Defo looks as if a cooler, rather than a warmer outlook is starting to take hold, now -- there are fewer warm 'options' within the ensembles, now, than has been the case in recent days...?

   

   

Perfect!love going for a run on those cold crisp autumn mornings❄!!dont mind if its cold and crisp in autumn as long as its dry!hate the dank rainy weather we been having so far this week dont need that

[ItNeverSnowsInWindsor]

2 hours ago, JON SNOW said:

My opinion of the mean is that longer term it indicates a N/S split with the most unsettled weather further north and temperatures generally around average but a tad below further north..pretty average normal october conditions...and as far as winter is concerned, this means nothing!

The bigger picture is the switch to more unsettled conditions and hints of a more southerly tracking jet stream. Solar minimum winters which have been cold tend to feature southerly tracking jet stream

[MATTWOLVES 3]

Everything looks a mess these next 10 days.... The models obviously struggling with the storm tracks! One thing for sure is, the ECM seems to have dropped the pressure rising scenario. But good god, just take a look at the ensembles.... Its literally like a person of a nervous disposition took a lie detector test!! Anything looks possible. 

[summer blizzard]

Sadly the 6z has a more normal n-s outlook in FI however the message so far seems to be that the first third of October will probably still be quite wet.

[SMU]

cAfternoon All-

Its early doors in terms of venturing to much into the MOD thread however with the run in to 19/20 eagerly awaited - The current juncture seems a decent point to inject a bit of 'cold' optimism.

Current persistence of the -NAO 2019 has been record breaking throughout AMJJA - However with a spike into low positive territory early Sept the thoughts of the negative trend lasting through Autumn & Winter probably took a hit. 

We have now possibly moved through this positive phase into a negative oscillation which initially appeared to be a temporary affair- however increasingly as the pressure field over the pole gets better resolved & approaches ~ 144 > 168 so the possibility of a more sustained -NAO period with High pressure in situ over Iceland appears likely.

The 12z ICON goes full undercut -The GFS has morphed towards this from the 06z but not fully & the 00z ECM had no energy underneath.

ICON

GFS

Its at times like this the models & mid term signal often follows the persistence of the ongoing NAO pattern - & in Autumn / Winter thats usually working back towards positivity- however on occasion it would seem no matter whats thrown at the models they gravitate to cold - 2009 / 2010 / 2018 being some examples where all roads lead to cold despite mild being the trend to start with.

If you overlay this with the ongoing thoughts ( raised by me at least ) that the arctic is going through rapid 'evolution' then if this evolution is ever to drive a higher frequency of cold / very cold episodes in the UK then the undercut type scenario has to happen in Oct > & also Nov in December. Which of course will go against the current seasonal outlook.

cheers

S

PS the undercutting scenario is certainly better for SAI / westward snow movement out of Russia.

Edited September 26, 2019 by Steve Murr

[ItNeverSnowsInWindsor]

So the latest GFS 12z continues with the favourable jet angle and cool theme from earlier runs. See where the op sits in the ensembles..

Edited September 26, 2019 by prolongedSnowLover

[tight isobar]

Andd.     .

It's high time to fall off that now cracked summer fence!!!

 

I can't remember tbh being quite so exited by the very early prog/early notions sliding into the vastness/madness..of our deceiptful/-sometimes -comical winter months!!

 

A pretty basic 1 for starts.

But my eye is taken via many factors as we slowly roll in..

But the immediate shunt..is the northern hemisphere snow forms.

Taking the oceanic stills and likely formats as we progress..

The the evolving 'likely' strains on pressure squeeze into the upper/higher latts..it's certainly spiking early interest!!.

 

In simple terms 'right NOW'..

The extent...And cover formats will hold a high sign for us/those seeking early preference to 'perhaps' a good shape going IN!!

 

Large scale missing except on the previous format subject-2018-..

Yet already the minamal raise!! 

And certainly an-earmarked upage on a northern eatern early impact!!!..

Now that  is-what ya want to be seeing..in regards to latter nw blocking format..

And most definitely...

For encouraging N/N/E polar incursions...

Not going into other forms..ie upper layer influences..Just yet..but.. 

It's definitely...a roller...early on this 1!!!!!

 

Edited September 26, 2019 by tight isobar

[tight isobar]

And nearer terminology!!..

A good representation..

Of the decline.

 

And Scandinavia COOLING....

 

Edited September 26, 2019 by tight isobar

[johnholmes]

4 minutes ago, tight isobar said:

And nearer terminology!!..

A good representation..

Of the decline.

 

And Scandinavia COOLING....

 

Ah, thank you, one in the English I understand, but welcome back ti

[shaky]

13 minutes ago, tight isobar said:

Andd.     .

It's high time to fall off that now cracked summer fence!!!

 

I can't remember tbh being quite so exited by the very early prog/early notions sliding into the vastness/madness..of our deceiptful/-sometimes -comical winter months!!

 

A pretty basic 1 for starts.

But my eye is taken via many factors as we slowly roll in..

But the immediate shunt..is the northern hemisphere snow forms.

Taking the oceanic stills and likely formats as we progress..

The the evolving 'likely' strains on pressure squeeze into the upper/higher latts..it's certainly spiking early interest!!.

 

In simple terms 'right NOW'..

The extent...And cover formats will hold a high sign for us/those seeking early preference to 'perhaps' a good shape going IN!!

 

Large scale missing except on the previous format subject-2018-..

Yet already the minamal raise!! 

And certainly an-earmarked upage on a northern eatern early impact!!!..

Now that what ya want to be seeing..in regards to latter nw blocking format..

And most definitely...

For encouraging N/N/E polar incursions...

Not going into other forms..ie upper layer influences..Just yet..but.. 

It's definitely...a roller...early on this 1!!!!!

 

Boy have i missed you mate!!good to have you back!!ive come out of hibernation last couple of days aswell ready for the winter season!!!nervous and toys thrown out the pram moments coming up

[ItNeverSnowsInWindsor]

6z vs 12 GEFS. A definite trend towards the cooler scenario.

[Methuselah]

Aye peeps, the descent into Autumn is well underway!

   

   

Welcome back TI...Winter beckons!

Edited September 26, 2019 by Ed Stone

[knocker]

As the winter brigade is back early time for the rest of us to depart Adios

But one last thought. It would have been interesting on OWS stations Juliet and India with this scenario

 

 

 

Edited September 26, 2019 by knocker

[Frosty.]

Certainly the GEFS 12z mean longer term has the polar front jet to the south of the uk compared to earlier today so we are on the cool / cold side of it and it looks generally unsettled, having said that there's a big spread in outcomes ranging from semi-summery to semi-wintry.

Edited September 26, 2019 by JON SNOW

[MATTWOLVES 3]

3 minutes ago, knocker said:

As the winter brigade is back early time for the rest of us to depart Adios

 

 

Hold your horses knocker... I no me and you have never really seen eye to eye, but you do one hell of a round up during the early mornings... Personally I think it's a tad premature with the winter drum being banged in September... But each to there own I suppose! I'm not even seeing anything at this stage to suggest winter is coming early... But like I said to my knowledge, it's nearly 3 months away still. 

[I remember Atlantic 252]

56 minutes ago, Ed Stone said:

Aye peeps, the descent into Autumn is well underway!

   

   

Welcome back TI...Winter beckons!

As I agree with welcome back T.I, I'm still in summer mood living here in Sept, northerlies here for next 5 weeks would just be around 10 degrees, and will feel just as vile as a January day with a SW'ly breeze

[damianslaw]

A trend appearing to cooler and generally unsettled weather predominating with a temporary quieter interlude to start October with possibility of first widespread ground frosts at least, and air frosts in places under chilly uppers.

Models are playing around with ex-tropical storm features and the jet and how these interact with strong heights to the north. Ex tropical storms are very difficult to forecast, and can take unusual trajectories - sometimes filling in situ, other times becoming large cut off low scenarios - sometimes splintering into bits, other times spawining parent low pressure systems which again take odd routes. Its no surprise to see the models therefore showing potential for undercutters and slider troughs thanks to a stalling feature coming unstuck against what appears to be a growing strong block to the north.