Model Output Discussion 01/09/17

[feb1991blizzard]

3 minutes ago, DJ RY said:

Big change there, yesterday it was showing temperatures up to a balmy 21C in the south next Sunday 

Here comes the second go with a more favourably shaped ridge.

[blizzard81]

2 minutes ago, DJ RY said:

Big change there, yesterday it was showing temperatures up to a balmy 21C in the south next Sunday 

If this comes off I would be much happier if it was a month later. But beggars can't be choosers I suppose. 

[feb1991blizzard]

Snow for inland areas even quite far South!!

 

Edited October 21, 2017 by feb1991blizzard

[snowflakey]

10 minutes ago, feb1991blizzard said:

Here comes the second go with a more favourably shaped ridge.

Temps widely into single figures, and snow over the high ground in the north I would think.

[Man With Beard]

First truly cold op run of the season on the GFS 06Z! Seems to have support in the ECM 00Z control run:

[Polar Maritime]

Yes the 6z likes to realy cool things off, With much more seasonal charts on offer, High Pressure pushing well up into Greenland blocking the Atlantic bringing a cold Northerly flow turning N/E towards the end of the run into Wk2. All a long way off, But interesting all the same. Not disregarding the models are realy struggling currently as they tend to at this time of year..

 

[feb1991blizzard]

The aforementioned evolution not without support on the GEFS either, not overwhelmingly so but its starting to get a tiny bit more troughy on the mean that tad further South to the East of us.

Edited October 21, 2017 by feb1991blizzard

[Methuselah]

22 minutes ago, Polar Maritime said:

Yes the 6z likes to realy cool things off, With much more seasonal charts on offer, High Pressure pushing well up into Greenland blocking the Atlantic bringing a cold Northerly flow turning N/E towards the end of the run into Wk2. All a long way off, But interesting all the same. Not disregarding the models are realy struggling currently as they tend to at this time of year..

 

Looking quite good for some coastal convection, too...

[knocker]

Ah well

Sid isn't phased

[Met4Cast]

Well well well. Now things are getting a little interesting. A few members have been posting some cold synoptics from the ensembles for a couple of days now and now the OP is showing these types of charts too.

The op is one of the colder members within the suite but it's certainly not entirely without support. There's a definitely cooling trend towards the beginning of November too. I think the OP is the coldest/best we can hope for, but it does feel a little too early for me.

Widely into single figures with snow likely particularly in the North, but nothing "extreme".  Who knows, tentative at this stage.

[Daniel*]

A rather cold northerly airstream evident as early as T+174 Sidney has scarpered I appreciate the consistency from the GFS. I feel this November is going to be 'interesting'. 

 

[Ross Andrew Hemphill]

Models cooling down the UK into November is looking interesting, although once it's within T+100 I'll take notice more (well I'll try not to take notice until then!).

[booferking]

Been on the cards for days now (Ensembles) its now appearing on the op runs a welcome cool down for Western Europe now just to get it in the more reliable period. First frost of the year for many maybe even a wintry shower in the far North.

[sundog]

It always seemed like there was a chance showing this week of something much cooler for the end of Oct/start of nov ,seems to have slowly but surely gathered some momentum.

[JBMWeatherForever]

Starting to look like winter might be starting early this year. There is certainly increasing evidence of a cold pattern taking hold as we move into November. Models look increasingly promising. The trend is are friend.     

[knocker]

My understanding is that councils up and down the land have the gritters on standby.

[chrisbell-nottheweatherman]

59 minutes ago, Ross Andrew Hemphill said:

Models cooling down the UK into November is looking interesting, although once it's within T+100 I'll take notice more (well I'll try not to take notice until then!).

I tend to take the view that, given the greater experience the models receive in terms of our prevailing mild, zonal winter weather, when cold is showing, I like to see it get within t+96, or even t+72 before I allow myself to get too interested.

[JBMWeatherForever]

I just like the rinse and repeat pattern which just seems to be being set up by the models on the whole, where we may not get decent cold first time but down the line we do. This is the models output discussion thread after all. And yes of course everything is always more certain within 96 hours, I just think the charts are increasingly promising to my eyes. 

[Nick F]

7 hours ago, Man With Beard said:

First truly cold op run of the season on the GFS 06Z! Seems to have support in the ECM 00Z control run:

With the MJO progression through 7, 8 and maybe into 1, this could be the precursor to a pattern change, certainly ENS and some high res runs have been hinting at blocking in the NW Atlantic vicinity and troughing to our east and also a cut-off trough around the Azores areas in the next 1-2 weeks. May even get more of a -NAO signal as we head toward early Nov given MJO progression. But no guarantees of this.

12z GFS seems to have shrunk the warm spell next week, with shorter duration of WAA Tues-Thurs, with temps hitting the high teens in S and E England, before a cool down from the NW by the end of the week, then big cool down over the weekend. Sunday week GFS shows afternoon temps struggling to get into double figures even in the south.

 

Edited October 21, 2017 by Nick F

[Captain Shortwave]

Quite a change over the past 24 hours. The ECM shows this nicely coparing todays day 5 chart and yesterdays day 6.

   

A flatter upstream pattern results in a weak dig southwards of cold air in the Atlantic and a faster process of cutting that low off, hence a less pronounced burst of warmth from the south. So even by Friday a cooler north westerly flow will be developing. 

A word of caution on those cold looking charts in week 2, the same scenario could occur which could scupper a potential cold plunge if the models have over amplified any northerly flow at the very end of the month. That said the evolution in question (The initial burst of warth with pressure building close to the UK and then retrogressing is supported by the MJO progression). It is a question of whether the models are over-egging the responsible by making it too dramatic or indeed too quick. Still the pattern remains interesting going forward.

Edited October 21, 2017 by Captain Shortwave

[knocker]

So what with the ecm this evening. No problem by Thursday 00 with the split upper trough to the west and amplification underway. Thus the surface analysis of a surface low SSE of Iceland, another away to the south west and the Euro high pushing north  So a classic N/S split with the north under the influence of the low and the south the HP. Similar to the previous run except the norther low a little more advanced thus squashing the ridge somewhat.

By midday Friday the low has tracked east to be north of Scotland but there are further complications as the front associated with the low to the south west (which still has a connection the other trough) has developed little waves on it and all travel north east  to impact, with rain, England and Wales on Friday. The front and rain track quickly south east leaving the UK in a showery north westerly by midday Saturday

Twenty four hours later the next deep upper trough has emerged from N. Canada and is over Iceland (The same pattern change that has dropped a very cold upper trough over eastern N. America) and this completes the job of squashing the Euro high and plunges the UK into a strong westerly flow, albeit still tending a north south split with temps around average maybe a little above.

I still wouldn't like to bet the bank on the detail for next weekend and beyond.

Edited October 21, 2017 by knocker

[iapennell]

1 hour ago, chrisbell-nottheweatherman said:

I tend to take the view that, given the greater experience the models receive in terms of our prevailing mild, zonal winter weather, when cold is showing, I like to see it get within t+96, or even t+72 before I allow myself to get too interested.

My view as well. Firstly, it'll probably be too little, too late for the cold air to bring about air-frost before the end of the month: For most of us, that is. 

Secondly, the various models can fast change their outlook in a matter of days,  so I don't consider the forecast cold-weather pattern to be "In the Bag" unless the predictions are consistent across a range of (Ensemble)  Models for within five days ahead! 

So, I'll not be getting my hopes up yet!! 

Ian Pennell 

Edited October 21, 2017 by iapennell

[phil nw.]

Ah well as already noted by quite  a few members the first cold charts of the Autumn are showing up on the GFS.

The wavering jet pattern always leaves these possibilities on the table, after all we have been on the warm side of the amplified pattern and will be again for a while this week, so why not go cold when the pattern realigns?

This particular one though is some days away and as ever we need agreement across the board before confidence can build.The main question is the degree of amplification to come we need a fair bit to get a northerly here as we know.

A look at the differences at day 6 show we have a way to go

 

Note GFS has already modelled the pv differently to the other 2 putting more low pressure across the Scandinavian region and less on the Canadian side and goes on to show a sharper trough deep into C.Europe later whereas ECM doesn't.(see images further down)

MJO forecasts into Phase 8 by early Nov do relate to mid Atlantic ridging

However on these ECM shows less amplification which is reflected in the Operational charts by day 8  compared to the GFS model.We can see on the ECM the MJO wave is losing strength and heading towards the centre or circle of death as we call it.

  

One to watch though to see how modelling and the MJO forecasts develop this in the coming days but good to see some early season interest even though it may prove a little early for many of us if it did transpire.

Edited October 21, 2017 by phil nw.

[lassie23]

With northerlies showing up on weather models, more often or not, it's here today gone tomorrow.

[Allseasons-Si]

Late to the session,been a bit busy but just to reflect on what has been said above,i would like to add a little bit more meat to the bones as you would say

the latest NAO and AO ens are showing a more neg trend than yesterday with some dropping to -4 on the AO,and the 8-14 day 500mb outlook from NOAA reflects this with a trough over Scandinavia and high pressure in the atlantic ridging into Greenland,blocky! blocky!

London,German and dutch ens all trending cooler from around the turn of the month(November)

There is a couple of things niggling at me though that this attempt could be a false dawn and we(as we say it every year)may need a few more bites at that cherry again

let the interesting times begin

Edited October 21, 2017 by Allseasons-si