Model Output Discussion - 05/01/2016 18z onwards

[Polar Maritime]

A few more posts have been hidden, Again 'Only Model Output Discussion' in here please.

Edited January 9, 2016 by Polar Maritime

[J10]

Here is the latest Snow blog for the Alps.

 

This does contain a look at the models though for this week, so worth having a look for the current synoptics, even if terms of the UK.

In terms of the Alps, the chance of some very heavy snowfalls say above 1800m. So conditions slowly recovering after a very bad start to the season.

 

[IPredictASnowStorm]

Need a better Gfs run this high keeps getting in

[cyclonic happiness]

Just now, IPredictASnowStorm said:

Need a better Gfs run this high keeps getting in

That's not necessarily a bad thing. 'If' we have nationwide snow cover, a HP drifting over us will keep the snow intact and the temperatures at the surface will drop into some very juicy number.

High pressure after snow is a very good thing 

[Nouska]

Just before the CFS January forecast drops off the output, this must be one of the most amazing about turns we have ever seen....

.... from almost off the scale warm anomalies 

...to this in the space of a couple of weeks         

 

 

[MP-R]

7 minutes ago, IPredictASnowStorm said:

Need a better Gfs run this high keeps getting in

Yes not the best run at all from the GFS, very messy in the reliable, a rush to get high pressure in then a sinking high, which if it verified as shown, would mean game over for any prolonged cold. Early days though so a case of 'keep watching'. The ECM is slightly better, keeping the high in situ rather than just sinking it a la GFS.

5 minutes ago, cyclonic happiness said:

That's not necessarily a bad thing. 'If' we have nationwide snow cover, a HP drifting over us will keep the snow intact and the temperatures at the surface will drop into some very juicy number.

High pressure after snow is a very good thing 

... that is if there is lying snow, which requires a vast improvement in what's being shown. Would be nice to a get a retrogression of the high to the northeast. That Azores low is proving as much of a pain as the Azores high at the moment.

[I remember Atlantic 252]

Like Nick, I have been watching this channel low, just hope ECM can stick with it, and not send it to France, could be a setup for my location similar to Boxing Day 2014, with a snowy low, then HP building in afterwards, agree with CH on this

[northwestsnow]

Excellent ecm ens for london

Edited January 9, 2016 by northwestsnow

[nick sussex]

I will be interested to see the latest MJO forecasts later.

Although we didn't quite see the robust Greenland high, the pattern in the north Atlantic does show an MJO phase 7 response in terms of the composite anomalies.

Moving forward the next key phase would be 1. The GEFS seemed reluctant to move the signal there but have it meandering around phase 8.

The ECM more bullish about phase 1. Preferably we'd like a scoot through phase 8 and it setting up shop in phase 1.

Now if you look at the composite anomalies for phase 8 this has been replicated in some recent GFS runs with a more Euro high situation:

Now my interest has been raised by the ECM T240hrs output where we can see things starting to move towards that phase 1 anomaly:

Lets compare that to the ECM T240hrs:

Are we beginning to see the upstream pattern heading towards the phase 1 MJO.

We haven't quite managed those negative anomalies towards the length of the Med but that would happen eventually with a strong block to the ne and the upstream troughing would disrupt energy underneath.

I think we've been a bit unlucky with how the cards have fallen over the last few days. Can we get a bit more lucky if the MJO does manage to get into phase1?

 

 

 

 

Edited January 9, 2016 by nick sussex

[chicken soup]

1 hour ago, karlos1983 said:

Lets not lead ourselves up the garden path too much. We've seen where that lands us. I'm happy with the 06z from GFS in comparison to the 00z, but I'd like to see it the same or bettered on the 12z and at least some cross model agreement. Then I'll be happy(er)

we've already had cross model agreement earlier in the week, and it still went wrong...for whatever reason all models seem to struggle with anything different than a zonal pattern.

[Interitus]

1 hour ago, Weather-history said:

Why do models struggle with modelling over the plateau? That 1080mb is definitely model struggle. 

Why do people think that this is model struggle? For all stations the local pressure is reduced to sea level, unless at that altitude already, using standard formulae. Without even a notable Greenland high within the past month, on 16/12/15 Summit base on top of the icecap at 3200 metres recorded 655.3mb with -59.9°C which equates to 1069mb at sea level - the GFS charts showed values of 1045+ for this time. This reduced air pressure to sea level is not without possible error as it assumes a known temperature lapse rate but the simple advantage of these ETA coordinates is that the surface charts allow instant accurate recognition of pressure wind from the isobars, other coordinates such as Sigma elevation above the surface or potential temperature may not.

[Catacol]

10 minutes ago, nick sussex said:

I will be interested to see the latest MJO forecasts later.

Although we didn't quite see the robust Greenland high, the pattern in the north Atlantic does show an MJO phase 7 response in terms of the composite anomalies.

Moving forward the next key phase would be 1. The GEFS seemed reluctant to move the signal there but have it meandering around phase 8.

 

 

Yesterday's UKMet and Canadian MJO forecasts were also moving towards phase 1. GFS is out on its own. Billy no-mates and no-hoper?

[Spah1]

 

Which little feature is giving us 30%?

Maybe this? 

 

[nick sussex]

6 minutes ago, Catacol said:

Yesterday's UKMet and Canadian MJO forecasts were also moving towards phase 1. GFS is out on its own. Billy no-mates and no-hoper?

Lol! One could argue that without the MJO movement we wouldn't even have a chance of this colder spell. I don't think its coincidence that the MJO phase 7 timelag response has seen the improved picture over Greenland and to the west of the UK. For that reason I'm hopeful given the so far good correlation with the MJO that something will pop up towards the day ten range.

The transition between phase 7 8 and 1 we need to get through hopefully with enough residual amplification left over from phase 7 for that high holding onto the surface cold before the upstream troughing digs south and forces that ne'wards.

Edited January 9, 2016 by nick sussex

[Methuselah]

Looking at that chart suggests some ideal conditions for evaporative cooling: very light winds, heavy precipitation and starting temps of maybe 3-6C...Christmas Eve 1968 comes to mind...

[Frosty.]

With all the current uncertainty about how long the cold spell lasts once it arrives through the middle of next week, it's nice to see the GEFS 6z mean showing the UK in an Arctic airmass out to the very end of next week with wintry showers and frosty nights and mornings with icy patches. Beyond that, high pressure could build in and bring crisp sunny days and frosty nights.

[Daniel*]

59 minutes ago, IPredictASnowStorm said:

Need a better Gfs run this high keeps getting in

Interestingly it's the coldest day on ECMWF Brrrr, temperatures not going above freezing for most. Some snow flurries for my region before turning settled locked in cold at surface. Despite uppers moderating somewhat from the W along with pressure build, cold, frosty, dry, sunny, weather seems seems likely into week 2. Not seeing those SW'lies anytime soon. Does turn quite stagnant I'd expect some very cold nights. Well let's see what the upcoming week has in store with snow possible north & south a threat of significant snowfall, that is where my focus is at this moment of time. It is advisable you retreat from your screens, so you do not miss the cold spell altogether.

  

[stewfox]

43 minutes ago, northwestsnow said:

Excellent ecm ens for london

Not sure if model or learning thread . Can someone clarify for us simple folk trying to learn what this graph is telling us.

I assume reasonable agreement out to FI or 17/1 ie limited scatter and then scatter increases as you would expect but then a large divergence between ECM and NECP.

What are those red a blue lines ? do they represent the average for the ens for those models ? and hence a large dis agreement post 17/1 

[Nouska]

9 minutes ago, stewfox said:

Not sure if model or learning thread . Can someone clarify for us simple folk trying to learn what this graph is telling us.

I assume reasonable agreement out to FI or 17/1 ie limited scatter and then scatter increases as you would expect but then a large divergence between ECM and NECP.

What are those red a blue lines ? do they represent the average for the ens for those models ? and hence a large dis agreement post 17/1 

The red line is the ECM deterministic, the blue line the GFS operational and the yellow is the mean of the ECM ensembles shown as the grey lines.

[Ali1977]

2 minutes ago, Nouska said:

The red line is the ECM deterministic, the blue line the GFS operational and the yellow is the mean of the ECM ensembles shown as the grey lines.

Well one of them is way off the mark by next weekend, hopefully the GFS !!! 

[carinthian]

I think there is no doubt now from the UKMO that Arctic Maritime air mass will be established over most of the land by  mid -week, could still be a little earlier or possibly later but will get there. Great to see later how that low  develops that now showing up in Biscay on the last fax picture. Still the view from over here, Northern France its likely path with a more pronounced low circulation rather than a wave. That would produce some rather stormy weather in the SE as exits the land. Still lots of interesting model viewing to watch over the rest of the weekend as the cold spell  develops.

 C

[phil nw.]

9 minutes ago, stewfox said:

Not sure if model or learning thread . Can someone clarify for us simple folk trying to learn what this graph is telling us.

I assume reasonable agreement out to FI or 17/1 ie limited scatter and then scatter increases as you would expect but then a large divergence between ECM and NECP.

What are those red a blue lines ? do they represent the average for the ens for those models ? and hence a large dis agreement post 17/1 

Hi stew,

The red line is the ecm op and the blue is gfs op from 00z hrs.The grey lines are the 50 ens members from the ecm suite all run at lower resoultion than the ecm op.The yellow line is the mean or average line of all the grey(ens members)lines.

You can read that on the page here

http://www.weathercast.co.uk/services/ensemble-forecast.html

I see Nouska has beat me to it!

Anyway just to add some thoughts on those graphs.Next weekend again shows as the key point of where we head into week 2.

A glance at the 2 op charts from the 00z run at T192hrs.

gfsecm

 

GFS quickly returning us to a milder westerly pattern and sinks the high.ECM showing our high much more resiliant as it holds the Atlantic back and we remain under the cold block which extends by then over much of Europe.

If ECM is the right call for week 2 i fancy that will result in a blocking high further north or north east as tropical air is pumped way north into the Arctic up through the Eastern Atlantic.ECM T240 would be a good start

I can see plenty of twists and turns on this yet as the models work out the balance between the strength of the Atlantic jet coming against the cold block now resident of much of N.Europe.

This cold now settling over the northern half of Scotland will soon be filtering across the border through the coming 2/3 days.  

[Mucka]

Model summary.

GFS 06z another horror show which follows on from the 00z by phasing the Greenland shortwave with Atlantic trough which given the model has led the way with the Icelandic shortwave is a worry. It also has gathering support within its own ensembles though the majority still against such an evolution.

I would like to see it drop that in this evenings output otherwise I fear it may well have picked out the next spoiler and the Euros will be playing catchup again. How is it the Euros verify better except when it is cold they are modeling? Sick joke of the weather Gods.

On a more optimistic note ECM  is much better though again there is massive scatter within the ensembles. If the Atlantic trough does not phase with the Greenland shortwave and flatten the pattern there are signs that the ridge will want to restrengthen although the pattern looks like being forced East which would mean the UK being under a cold ridge/high with the possibility of high pressure building into Scandinavia thereafter.

It will turn colder through next week with sleet and snow for some with 3 days of colder weather assured. Thereafter we will either have the Atlantic pushing back in through the weekend and turning unsettle and milder (GFS) or it will remain cold but become drier with the caveat that there is a small possibility of low pressure moving across the South giving rain/sleet and snow for a time and an even smaller possibility of a period of snow for the E/SE later as low pressure moves down the Eastern flank of the country. (ECM)

Going further out(10-15 days) GFS would likely slowly dry up from the South with temp average or a little above while ECM could well remain cold and largely settled with a chance of an Easterly type flow setting up.

 

Edited January 9, 2016 by Mucka

[joggs]

Surely you'd have to back the GFS given the meto further outlook?.

[doctor32]

I think crucial time for model watching today is between 96 and 144hrs as thats where the models start to differ and then the following timeframes change quite abit. have a feeling that ukmo and ecm will be more close to the mark and will see gfs 12z as a better run when it comes out.

hopefully over the next 48hrs we will start to see which areas are more likely to see snow aswell