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

[MR EXTREMES]

I see reload possible if this is correct maybe leading to back edge north easterly if the heights retreat to our south.

Greenland high not giving the title back to the vortex although vortex for now looks like fighting back on most of the other model runs but the 180 chart more progressive than this mornings run with greeny heights filtering away although id take this with a pinch of salt for now.

also interesting to see what mjo 8 into phase 1 will lead to I remember December 09/10 onwards see a lot of phase 1 phase 8 so be interesting to see if end of jan feb could turn into a classic wintry pattern.

Edited January 11, 2016 by emotional rollercoaster

[karlos1983]

Groundhog Day 

[Geordiesnow]

11 minutes ago, mountain shadow said:

I'm confused.  Geordiesnow says this run is less amplified yet Ali1977 says we have a Greenland High? ??

Well it is less amplified compared to the Euro runs in the short to medium term, although some sort of an attempt to build something interesting but does not get there. Certainly no Greenland high on this run as far as I can see either. 

It also brings the Atlantic in a lot quicker than the Euro models and you got to say it is looking more and more plausible that the Atlantic will come in but how long will that take is very much open to question, hopefully as some sort of consolation prize for what looks like a week where snow will be limited, if/when the Atlantic does come in, we will have some sort of cold air with some strength behind it so at least there will be some frontal snow to look forward too. 

As for any easterly, I would not rule out some sort of easterly flow out either, there have been some hints in it but at this stage, any easterly flow will probably just delay the inevitable of the Atlantic coming back in but at least we should get some colder air so any frontal snow would be a higher risk.

[BLAST FROM THE PAST]

23 hours ago, BLAST FROM THE PAST said:

Well models settling towards cold extending on.  For me correct.  

 

 

Great UKMO and ECM not too dissimilar and the crucial point for me. ECM continues to move the HP east but remains cold.  I'm thinking any higher pressure will be transitory and that we'll end up being a under very deep trough situation bringing air from arctic origin [where it places itself eg over us or just to our east of note ].  I think HP will remain in Greenland locale thus PV remaining disrupted/displaced,  but I'm seeing enough now that the models have got over their 'destroy the cold' wobbles and we move towards a very wintry period for the UK.  It remains that my thoughts for first half of Feb being in coldest part of winter remain, so onwards and upwards and enjoy the ride.

 

BFTP

 

 

 

Ok to quantify on aboive but first just to say 00z are good for cold and the fact we have cold spell on our doorstep in mid Jan is a lovely thing to have and uncommon in recent times.

Now re part in bold, the 00z showing HP sliding over UK, I'm not in the camp of it staying far enough north to bring in an easterly, indeed I anticipate it to collapse/pass through/slip away SE'wards and then another more potent trough sets in bringing truly arctic air to our shores for last 3rd of the month and some very wintry conditions.  Anyway hopw this plays out we shall see but this all bonus for me as I still think Feb remains in place [weatherwise...I know month does lol] and so we could be in for a protracted  period of cold with slight milder interlude before a reload to colder still.  I think RJS was suggesting this type of scenario quite a few days ago re cold then milder trying to shove in and cold then really taking over.

I think enjoy what's coming, there could be neartime local upgrades as for example yesterday was supposed to be 9c where I live...it didn't get above 6c and plummeted with a hailstorm.

 

BFTP

[Paul33]

28 minutes ago, mountain shadow said:

I'm confused.  Geordiesnow says this run is less amplified yet Ali1977 says we have a Greenland High? ??

Unfortunately the title "Model Discussion Thread" is a bit misleading to those of us who observe and try to learn. There are obviously various different models and various different ensembles out there such that those on here with a bias - for whatever reason - towards ramping mild or ramping cold will always find output from somewhere that appears to back his or her case.

Its frustrating but its entertaining and at times like this, it just underlines that no matter what your chosen model says, anything can happen !!!

[Connor Bailey Degnan]

Nothing cut and dry yet, however, best chance of any 'significant snowfall' looks to be west and east coasts this coming week/end

[samalllpop]

19 minutes ago, karlos1983 said:

Groundhog Day 

If i am not mistaken wouldn't this be quite a good chart for cold, with winds swinging to the north?

[Man With Beard]

Well anyone who got an early night and hasn't seen the GFS charts till now must be thinking they're in a bad nightmare. I mean, seriously, it's laughable.

This is so utterly different to its output (and indeed any output) that there is no possible way one could use the GFS to make a forecast at the moment. I have heard those saying "The GFS is the most consistent" - well, it does that - it stubbornly sticks to one pattern until the very last moment, and then when it realises it is wrong it throws the most almighty wobbly. 

Back to more sensible charts: De Bilt ecm ens:

you can see how a slow warm-up is still the main player - below freezing from Saturday to Monday (so maybe slightly above here), then a wide split but the most concentrated cluster stays below freezing until later in the week, suggesting a slow sinker.

[mb018538]

I would agree, I watched the 6z evolution and chuckled a bit. It's a bit like I don't know what's going to happen, so lets just explode the Atlantic and wind up the depressions again! As you say, so very different to the UKMO and ECM runs that I would totally disregard it and wait for the 12z for a better idea.

[BlueHedgehog074]

Just a fairly quick red line summary of the models for the next few days - looks as though some areas of ridging will be developing in the mid-Atlantic this week with another area of High Pressure around Greenland accompanied by some fairly modest upper heights there. All thanks to ridging of High Pressure moving Eastwards out of Canada/Eastern Canada to help form some blocking opportunities in the Atlantic. The Polar Vortex being unable to holiday at its favourite place to our North-West. This allowing troughs of Lows to drop down from the North-West ushering the UK in a cool to cold flow between the West and North at times with lowest of upper heights concentrated towards the Scandinavian area. Chances for 850 hPa temperatures of around -5*C or a little colder, especially towards Northern UK, to get pulled South and Eastwards towards us. And with thicknesses over the UK looking to be quite low at times some of the showers and longer spells of precipitation could have a wintry flavour at times. This more so over Northern UK parts. Perhaps something wintry for Southern parts as well, though it does look very marginal for this part at times with a risk of the -5*C 850 hPa temperatures getting mixed out from the West at times.

However, under heavy sustainable precipitation, this could allow evaporative cooling to take place and help drag the sleet and snow line down to lower levels. Not entirely impossible to get sleet and snow under 850 hPa temperatures a little warmer than -5*C - even if it's Atlantic sourced (suppose as longs other factors are favourable such as Deepoints being around/close to freezing - known it to happen in the past. But idealy 850 hPa temperatures do need to be at least around -6*C or lower for low level snow from the Atlantic, unless it's an Atlantic front trying to run into cold air over the UK). Suspect high ground Northern areas could get some quite big dumpings of the white stuff. Doesn't look as though there will be any major washout conditions and between showers/wintry weather, could be some bright, sunnier, periods with chance of some frosts overnight.

Maybe then a possibility for the mid-Atlantic High to get knocked over the UK towards end of the week as Lows coming East out of Canada/Northern America try to push up against the Atlantic and/or Greenland ridging. Although the models do continue to be somewhat unclear about the actual pathway they could lead us to near the end of this week and beyond. But having that ridge out West getting drawn over to us is quite a possibility. The NOAA anomaly charts show that kind of idea being a possibility with gradual progression Eastwards of the pattern. Nothing is always terribly certain though at those sort of ranges.

Hopefully, for those really wanting to see a flake or two (or more) fall from the sky, the weather will give some surprises for you.  

Edited January 11, 2016 by DiagonalRedLine
(correcting one or two typos)

[Weather Observer]

I have not lived here long, and remembering references in the past to fabled De Bilt, I looked it up on the map. It is not in the far reaches of the east as I had imagined but is actually as close to here as the crow flies as is Birmingham. Approximately 100 miles.

i know this will be a bit Imby to someone in Cornwall, but the Ens mean still shows -4c right up to day 9.  I will not get hung up about snow, but can look forward to a decent coldish spell with some sharp frosts. Also a lot can happen in that time. Just a small upgrade and we have a decent cold spell.

Edited January 11, 2016 by Weathervane

[nick sussex]

No don't do it GFS 06hrs run!

So we're moving back into the model dramas with the GFS less amplified early, it then refuses to cleanly eject the shortwave east, the Atlantic roars back but it keeps better heights over Greenland than the others.

For the GFS to be right both the ECM and UKMO would have to be wrong at T96hrs! Combined at that range I just can't see the Euros being wrong so this looks like another desperate cry for attention from the GFS.

 

[iamgazza]

1 minute ago, nick sussex said:

No don't do it GFS 06hrs run!

So we're moving back into the model dramas with the GFS less amplified early, it then refuses to cleanly eject the shortwave east, the Atlantic roars back but it keeps better heights over Greenland than the others.

For the GFS to be right both the ECM and UKMO would have to be wrong at T96hrs! Combined at that range I just can't see the Euros being wrong so this looks like another desperate cry for attention from the GFS.

 

One thing is for sure... we've got to be getting to decider time now. Tonight's runs will make or break and identify the culprit. I too am with you on the Euro's... Critical runs tonight.

[nick sussex]

2 minutes ago, iamgazza said:

One thing is for sure... we've got to be getting to decider time now. Tonight's runs will make or break and identify the culprit. I too am with you on the Euro's... Critical runs tonight.

I can't remember the last time both the ECM/UKMO showed the same thing at T96hrs and were wrong. Although the GFS did well last week the ECM had already dumped its UKMO partner for several runs and it was past T120hrs.

The ECM/UKMO have already put to bed that shortwave ahead of the main trough within T96hrs.

 

[Man With Beard]

[ ECM ensembles for London

(I believe this is an update, but that they forgot to change the time)

Close to freezing for a few days, slow rise in temperatures. Main clustering doesn't get back to 5C until 21st/22nd, and then a bit of a scatter as one would expect - but no deep cold in the days after that time.

Having said all this, I wouldn't be surprised if we get a highly volatile modelling period in the next few days - with blocks forming and disappearing over Arctic and Greenland, small changes in these areas will mean enormous changes a few days down the line for us. So although the "slow sinker" is preferred, the positioning of any high pressure is far from certain, and may be for a few days yet. These ensembles suggest to me no long-term easterlies among the options. ]

 

EDIT: Apologies, this was the wrong chart. Can't seem to post the chart in this comment so will do so below...

Edited January 11, 2016 by Man With Beard
Wrong chart

[karlos1983]

Edited January 11, 2016 by karlos1983

[Man With Beard]

 Can't get my computer to post the new ECM ens for London, so here's the link instead: 

http://www.meteo24.fr/fr/home/meteo-france-et-europe/passion-meteo/ensemble-de-previsions.html?eps=london

In fact, the ensembles on this run are colder than on last night's 12Z run. The average maximum temperature is below 3C from this Saturday until next Tuesday, and divergence in runs is little up to this point. Beyond that, some milder runs appear but I'd say the majority stick below 5C right out until D15. Which suggests no return to the Bartlett.

[Frosty.]

The Gfs 6z ends with a cliffhanger as a wall of snow marches towards the UK from the east

[Troubleatmill]

19 minutes ago, karlos1983 said:

I was just looking at the ensembles Karlos, would seem there are a few more members keeping us cold from the 17th ( where most of the scatter/uncertainty starts), could be changes afoot showing here

[Timmytour]

Frosty....from memory that "wall" has been around the last couple of years but never got pass Norway before.....the progress that's showing there may mean things are different this year!!!  (albeit a long way off!)

Edited January 11, 2016 by Timmytour
block to wall

[feb1991blizzard]

13 minutes ago, Frosty. said:

The Gfs 6z ends with a cliffhanger as a wall of snow marches towards the UK from the east

Most of that snow would be light frosty, what we would really need in that situation would be the frontal alignment out to the west of us to be negatively tilted giving a battleground, or the high to elongate west to east and to the North of us to get the really cold air in and give us a convective easterly.

Edited January 11, 2016 by feb1991blizzard

[Alexis]

http://www.meteociel.fr/modeles/arpege.php?ech=40&mode=1&map=300

Well worth watching the high res ARPEGE precipitation animation for snow chances Wednesday/Thursday 

[Frosty.]

7 minutes ago, feb1991blizzard said:

Most of that snow would be light frosty, what we would really need in that situation would be the frontal alignment out to the west of us to be negatively tilted giving a battleground, or the high to elongate west to east and to the North of us to get the really cold air in and give us a convective easterly.

Yes but I found the Gfs 6z to be very interesting as it keeps coldies in with a fighting chance of some wintry weather right to the end of the run and beyond. This week looks interesting too with some awkward situations for the professional forecasters as we see knife edge rain to sleet and wet snow situations developing through this week...at least it will feel like winter this week and hopefully next week too.

[Mark Neal.]

Don't forget we will be in Euro 4 (previously NAE) territory shortly, where we can see what the UKMO short term model is showing for Rain/Snow for the next 48hrs or so. Be useful from tomorrow. 

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=euro4&MODELLTYP=1&VAR=pslv&HH=0&BASE=-&WMO=&ZOOM=0

* That said looking at last few frames of the most recent Euro 4, next 2 days Scotland and N England the Euro 4 picking up on Snowier signal. 

Edited January 11, 2016 by Mark N

[Spurry]

I am by no stretch of the imagination an expert , in fact I'm pretty much a novice despite my 54 years, however one piece of advice(not sure who from , might be Mr Holmes) I have picked up over the years of visiting this forum is not to follow every single model release , the GFS 00z & 12z can be complete polar(no pun intended) opposites to the 06z & 18z due to the amount of raw data that is fed into them,I tend to take more notice of the 00z & 12z than the 06 & 18z(pub run), I find this helps to spot subtle changes and follow a pattern easier, also I find that they give more mid term accuracy . That's just an opinion and I may be wrong