Model Output Discussion 01/09/17

[SMU]

The models continue with the dramatic outputs signposting a significant modality change in the AO reaching the crescendo in about 11-12 days time around -4 to -5 index value

A full reversal of flow around the pole across ~70N- a unique & stunning chart

Still plenty of time for it to be watered down however the key for long term developments is around 168 with a reverse cross polar flow all the way from Russia to canada across the pole !

 

S

 

[Allseasons-Si]

The 18z is much better in terms of getting a blast from a NW'ly at day ten+ than the 12z westerly,i did mention the other day that i see a NW'ly influence from the models and there is nothing wrong with that at this time of the year,plenty of seasonal weather on the cards i would say

 

 

[Allseasons-Si]

6 minutes ago, Steve Murr said:

The models continue with the dramatic outputs signposting a significant modality change in the AO reaching the crescendo in about 11-12 days time around -4 to -5 index value

A full reversal of flow around the pole across ~70N- a unique & stunning chart

Still plenty of time for it to be watered down however the key for long term developments is around 168 with a reverse cross polar flow all the way from Russia to canada across the pole !

 

S

 

Yes ,but that chart entails a west based -NAO would it not?

[Snowy L]

2 minutes ago, Allseasons-si said:

Yes ,but that chart entails a west based -NAO would it not?

Yes, it looks like the problem is a stubborn Euro high (as usual) so instead of low pressure sinking into France/Germany giving us easterly winds, the low pressure docks over us. Though its not somthing we should be worrying about at this stage. It is a detail that we will only be more certain of in two weeks time (should we get the forecast northern blocking).

[bluearmy]

2 minutes ago, Allseasons-si said:

Yes ,but that chart entails a west based -NAO would it not?

It does and a west based neg nao is feasible at the rage we are talking about. I wouldn't be looking for anything of wintry note for our shores until past the 20th and that may be a few days too early. amplified charts will hopefully drive wave activity to disrupt the developing strat vortex. us missing out on a wintry sypnotic around the third week of November is fine by me if it means the building blocks are set in place for a blast of winter a week or two later. at the moment we are in no great hurry to see fantasy sypnotics across nw Europe in GFS fi. 

[bluearmy]

Incidentally, whilst the ecm London graph looks a tad less chilly week 2, it does show our first ice day on the ens  - 21/11!

[Mucka]

No watering down from the JMA extended yet. 

0

Edited November 7, 2017 by Mucka

[Snowy Hibbo]

and EC Weeklies....

14-20 Nov

Troughing over Italy and the Balkans, Ridging over the UK and Scandi. Jet mostly Zonal across the Atlantic. Precip forecast for most of the UK is drier than average. Snowfall anomalies are average. England is cooler than normal, Scotland and Ireland is average temperature wise.

21-27 Nov 

Troughing over France, Iberia and Southern UK. Strong Greenland/Icelandic High (I believe people have already touched in this). Jetstream heading towards the SE across the U.K. Precip anomalies over Western Great Britain are drier than average and over the Eastern Great Britain, is around average. Snowfall anomalies are average. The entire UK is cooler than normal.

28 Nov- 4 Dec

Troughing over Iberia and France, ridging over Iceland. Similar setup to the previous week with the jet and 500mb anoms in the region. Most of the UK is drier than normal, except the East Coast, which is average. Snowfall is forecast to be below average in the Scottish Highlands. England is cooler than normal, Scotland is average temperature wise

 

To compare, here is the SubX multi model ensemble forecast. It contains the typical GEFS and GEPS ensembles, and the less well known models, NAVGEM, FIM, NASA GMAO, and CCSM. These are all produced by various American meteorological agencies and research institutes.

11-17 Nov

It shows an Atlantic ridge with a troughing pattern across from Iceland to Italy, including past the Eastern UK.

18-24 Nov

Ridging anomalies from the Atlantic and over Northern Europe, including over the U.K. Troughing over Southern Europe and the Mediterranean.

25 Nov - 1 Dec

A ridge over Scandi into European Russia, with a weak ridging pattern across the U.K.

 

Anyway that's the sub Seasonal models.....

 

[Catacol]

1 hour ago, Interitus said:

Caution required - the 500mb geopotential height reflects the anomalous warmth of the Arctic, as can be seen in the 850mb temperature charts, there are only modest positive sea level pressure anomalies to the north at best.

I'm no expert on these models, but is this only a "modest" pressure anomaly?

 

Other charts I've looked at on there from all the models assigned seem to suggest conditions fairly good for the UK - though we all know these sorts of long term models are hugely suspect. ECM T2m chart had an interesting look to it - that's a signal for continental cold pushing west if ever I saw one.

[Mucka]

Looking at GFS ensembles I would say the Atlantic blocking signal is about as strong as it could be for last third of Nov this far out.

Hopefully we get lucky with the blocking and the cold signal will begin to pick up with it over the next few days.

 

Edited November 7, 2017 by Mucka

[booferking]

Plenty of blocky charts on the ens again they seem to be growing again thought I'd leave this one to pun on omega.

[ITSY]

Some of the ensembles are insane again - the NH profile really is bizarre for the time of year and totally at odds with recent years. Clustering on the evening run trending closer to -5 by the end of the run...and very tightly packed given the distance. Don't quite know what that means but clearly they are latching onto a signal...

Edited November 7, 2017 by ITSY

[geordiekev]

4 hours ago, nick sussex said:

Both the GFS and ECM develop some interesting NH patterns in their later outputs. Neither though show a straightforward route to much colder conditions.

The reason we don't get a more interesting T240hrs chart is the lack of amplitude of that upstream low so the energy piles over the top, more amplification upstream would help suck high pressure further north which then would force some energy to disrupt se from that low.

@nick sussex

Great to see you back with your red and black crayons, have learnt so much over the years from your fantastic analysis of where charts could/need to go for a shot at the good stuff. 

After all every perturbation chart is a tweak on the present conditions-a weaker low, a stronger high, further north/south. There's nothing to say that every tweak is wrong given the thousands of variables across the globe, so it's always a pleasure to see your own tweak which is as viable as every other ensemble out there. 

Keep up the good work,  was 9th November last year I got my first decent cover in similar disrupted vortex conditions so here's hoping for similar in the near future. 

[geordiekev]

1 hour ago, Jonan92 said:

What a strange looking NH profile for November

 November 10th last year was a bit similar, except for greenie heights, but let's hope the rest doesn't turn out similar. Quite eerie the lack of zonal storms again this Autumn, I guess recent years taught us zonal was the norm for Autumn, but maybe we are back into the real norm now

Edited November 8, 2017 by geordiekev

[Cheshire Freeze]

Should be a decent FI coming up hemispherically

At day 6 we're seeing better vertical advection into the Siberian side, may even see a bit more interest strat wise towards the end of the run.

[Cheshire Freeze]

Following on from my last post...

Small changes early doors (day 6) have big consequences further on as to how blocks align.

We're seeing the models generally sharpen up Pacific side ridging this morning- this is the GEM...

With the trop vortex still being in its relative infancy, it is being given a hard time- being ripped apart at will.

The issue is still there however, this is trop led and not strat led. The strat will couple with the trop at some point. We're just a smidgen too early for any deep cold as the GFS shows in FI. 

Edited November 8, 2017 by CreweCold

[Polar Maritime]

This morning GFS shows further variations of a cool sometimes cold N/W flow. 

 

Edited November 8, 2017 by Polar Maritime
Charts are back to front

[geordiekev]

Baby steps.....we are not used to November chills since the 90s so to have day to day signals of a cool set up, if not every 6hr run,  is promising.

The best odds I found for White Christmas in Newcastle this year is 4 to 1. I've never in 10 year of taking a festive punt had such short odds (3 yrs won)  and the bookies are rarely wrong, to think I won 8 to 1 in 2010, I think the odds are due for another win. 

[knocker]

I think the anomalies were adequately covered yesterday evening so just the latest GEFS and EPS AO which are pretty much as expected.

And a couple of lower Strat charts which are a fair facsimile of the 500mb field

Today sees the UK between pressure systems. Starting off fine and frosty in many places but the E/SE still influenced by yesterday's cold front hanging around so remaining cloudy until late on. Sunny elsewhere but fronts approaching from the north west will bring cloud and rand rain to NW Scotland during the day. Overnight and during tomorrow this will move south east leaving clearer and cooler weather in their wake but showery and quite windy in places particularly northern Scotland.

After a miserable attempt by the Azores to ridge NE on Friday  the frontal wave that has nipped around the high pressure is centred  over northern England whilst at the same time becoming incorporated in the circulation of the deep low ENE of Iceland. Thus a wet Friday evening and night for most turning quite wintry in Scotland but the wave is moving very quickly and by 12 Saturday is over Denmark. This heralds the much vaunted but very brief amplification as the wind veers northerly  bringing some general wintry weather with snow on the hills in the north

From this point the week and including next weekend can be summed up as the usual battle between the eastbound energy and the cooler air and the warmer Azores high pressure which the former wins. The jet is actually being forced further south across the US by the trough in western North America before swinging up around the Azores high cell and it does tend to get disrupted by the interaction with the high pressure before by the end of the week the more unsettled weather becomes established Thus a pretty mixed bag for the week with periods of mainly light rain interspersed by sunny interval before heavier rain and high winds enter the fray but this getting way too far ahead of ourselves.

 

 

Edited November 8, 2017 by knocker

[bluearmy]

Note the small chunk of vortex surfing the Arctic ridge n Siberia on the ec op day 8. That should traverse across to the Canadian side and cut off the ridging. If it doesn't it's a strong sign that we really could be in business from an arctic perspective which should encourage a more sustained greeny height rise. I think it was there yesterday's 00z run but absent on the 12z. 

Edited November 8, 2017 by bluearmy

[knocker]

The ecm still not agreeing with the gfs vis the wave on Friday/Saturday  It has it N. Ireland 00 Saturday but takes it and the rain across Wales and the southern half of England to be N. France, Belgium and NW Germany by 1200.

[blizzard81]

1 hour ago, bluearmy said:

Note the small chunk of vortex surfing the Arctic ridge n Siberia on the ec op day 8. That should traverse across to the Canadian side and cut off the ridging. If it doesn't it's a strong sign that we really could be in business from an arctic perspective which should encourage a more sustained greeny height rise. I think it was there yesterday's 00z run but absent on the 12z. 

I see that chunk. So are you suggesting game over if it traverses to the Canadian side?

[carinthian]

Arpage is looking to zip the frontal wave SE wards across the SW of England with the heaviest rainfall in the location followed by a swift return of the Polar Airmass to all regions.

 C

[johnholmes]

21 minutes ago, blizzard81 said:

I see that chunk. So are you suggesting game over if it traverses to the Canadian side?

game over!

8 th November, it has not yet started or have the seasons changed?

In the shorter range the wave position is quite interesting, how far north will it get, how much rain. Snow possible on the highest peaks of England and snow in showers for hills in Scotland?

 

Edited November 8, 2017 by johnholmes

[blizzard81]

17 minutes ago, johnholmes said:

game over!

8 th November, it has not yet started or have the seasons changed?

In the shorter range the wave position is quite interesting, how far north will it get, how much rain. Snow possible on the highest peaks of England and snow in showers for hills in Scotland?

 

I didn't mean game over for winter. Just in terms of how wintry it gets at the back end of November.