Model output discussion - 1st December onwards

[Zakos]

It is quite clear now that a major pattern change is underway, not just for the UK but for the entire hemisphere. The models are likely to flop back and fourth during such an event, I wouldn't trust any output beyond 5 days.

I thinks its unwise to completely discount a potential easterly next week. At the least I think there is potential for a battleground scenario over the UK.

The GFS is not as good as the UKMO, yet we have brutally cold air ever very close to our shores at t180

It wouldn't take much of a shift to see that cold air to be directed further west.

One undeniable trend from the GFS is that it continually underestimates how far south the jet stream will lie. Almost every successive run has the jet stream is further and further south, even within the 96 hour timeframe

I think there is still some chance of an easterly, though perhaps not sustained as the heights over Scandinavia are modelled to weaken at least temporarily.

Looking further ahead, The PV looks to be significantly weaker, and with the jet stream diving south I think we would have to be pretty unlucky to not get at least one notable cold spell during next month.

 

Edited December 29, 2015 by Zakos

[Froze were the Days]

6 minutes ago, Mucka said:

In terms of the weather this particular run gives the UK it isn't any better but in terms of the big picture and moving toward the Euros it as an improvement  with the jet further South and high pressure extending further West. Ignore anything beyond 168h for now.

I can see what your saying but unfortunately I still see to much activity in the Atlantic...sadly the undercutting scenario which would drive colder air more westwards is by and large disappearing even on the ecm  (other than the UKMO which still persists). All I can see into the New Year is a lot of unsettled cooler weather, maybe the best place to be is in the Shetlands or far NE of Scotland.

Edited December 29, 2015 by Froze were the Days

[Mucka]

3 minutes ago, MPG said:

Thanks very much.

Why are we still chasing the easterly?

I'm not sure what you mean?

The initial Easterly was always a long shot but as many said the jet was far enough South to give hope of further attempts at undercut - more bites at the cherry.

Essentially UKMO takes a big tasty bite on our second attempt and the flow comes in from the East, it may not be  a classic Easterly set up but it is still promising a cold easterly with good snow prospects, especially the further N and E you are, at least initially but UKMO promises to bring the snow line south and more direct East winds unless the low stalls and fills..

[bradymk]

This mornings runs in particular trended in the direction of less disruption of the trough with the atlantic further east. However, it seems it is all still to play for based on that UKMO run with the wedge of heights east of Iceland (GEM too) helping to disrupt the trough, so we await the ECM.

But even if next week doesn't quite deliver that cold and snow we all crave, the hemspheric pattern that is occuring in the models is going to give a major change into January with us likely to have a much better shot at a prolonged cold spell further into Jan. GFS later stages demonstrating the huge change. The pendulum has swung after the mildest December on record here...

 

edit: Massive change in the hemispheric profile in two weeks time...

 

Edited December 29, 2015 by bradythemole

[geordiekev]

24 minutes ago, Mucka said:

UKMO Boom!

 

I have noticed for a while that the dreaded Azores high has been looking at taking a mid Atlantic cruise and if the Atlantic lows begin to stall then hopefully we'll get a nice omega high. What an afternoon it's been, although only one run, so need to remain grounded.

[BLAST FROM THE PAST]

 

Now that is a very very good chart and not just wind and rain as one poster has it.  I think if that is how it progresses there's some very wintry weather to come.  Now to have alook at the others

 

 

BFTP

[terrier]

Well great looking ukmo tonight but not liking the gfs 12z looks wet and windy for many unless u live up in Scotland. Not great for areas round here. Think in this situation we will probably see a half way house between the gfs an ecm which often seems to be the case. 

[Mucka]

2 minutes ago, Froze were the Days said:

I can see what your saying but unfortunately I still see to much activity in the Atlantic...sadly the undercutting scenario which would drive colder air more westwards is by and large disappearing even on the ecm  (other than the UKMO which still persists). All I can see into the New Year is a lot of unsettled cooler weather, maybe the best place to be is in the Shetlands or far NE of Scotland.

 

It is impossible to know what the final outcome will be and we do not have consensus. UKMO has actually improved and we need to see what ECM brings this evening, GFS has been slowly moving more and more toward ECM and UKMO even though it still doesn't deliver as yet. 

We could get a GFS type solution or a UKMO type one and clearly the output is still in a state of flux so I don't think we can make a definitive judgement one way or the other.

Personally I favour something between UKMO and GFS but leaning more toward UKMO

[blizzard81]

6 minutes ago, Summer Sun said:

Significant changes as we move into 2016

 

 

I fear ukmo are 24 to 48 hours behind the game here. 

[Weather Boy]

1 minute ago, BLAST FROM THE PAST said:

 

Now that is a very very good chart and not just wind and rain as one poster has it.  I think if that is how it progresses there's some very wintry weather to come.  Now to have alook at the others

 

 

BFTP

Taking that chart literally, would it not mean rain for the SW 1/3 of the country i.e. south coast, S Wales and all of the SW?  They would be in a mild sector would they not?

Unless I am mistaken, I have yet to see any op chart that would given nationwide (or even near nationwide) snow?

I note that METO still very cautious, only conceding a low probability of a cold spell at a much longer time spell than these charts.

[Mucka]

2 minutes ago, Weather Boy said:

Taking that chart literally, would it not mean rain for the SW 1/3 of the country i.e. south coast, S Wales and all of the SW?  They would be in a mild sector would they not?

Unless I am mistaken, I have yet to see any op chart that would given nationwide (or even near nationwide) snow?

I note that METO still very cautious, only conceding a low probability of a cold spell at a much longer time spell than these charts.

That is correct but what would the 168 chart bring?

I think we are probably best just hoping for the full undercut for now and worry where the snow line might be later though clealry the further NE you are initially the more likely you will be to get some snow,

[Duane S.]

The GFS gives us a strong wave3 attack, delivers a complete Northern Hemisphere pattern change,  sends the tropospheric vortex scarpering in all directions and would in all likelihood set up a very interesting 2nd half of the month, cold-wise for the UK. Shame it is only one variation of many!

[Captain Shortwave]

10 minutes ago, Mucka said:

 

It is impossible to know what the final outcome will be and we do not have consensus. UKMO has actually improved and we need to see what ECM brings this evening, GFS has been slowly moving more and more toward ECM and UKMO even though it still doesn't deliver as yet. 

We could get a GFS type solution or a UKMO type one and clearly the output is still in a state of flux so I don't think we can make a definitive judgement one way or the other.

Personally I favour something between UKMO and GFS but leaning more toward UKMO

I have to congratulate the GFS there, for how much blocking throughout the run the GFS brings pretty much no snow to any low lying areas across the UK. That is some achievement. Some parts of the run are very very ugly with frequent bursts of heavy rain which will do no good for the areas currently experiencing flooding, the risk could also spread considering the rain will be much more widespread under this set up.

 

The UKMO is good and for a time the GEM is better

 

The GEM then goes wrong given a poor result betwen the two areas of cold pooling to the west and east of the UK

It turns into another rain-fest.

The models are never going to verify very well given these unpredictable pools of very cold and unstable air. There is still the chance of white-out conditions developing if things go well but there is so much risk and so much that could go wrong which means skis would be replaced by canoes.

Edited December 29, 2015 by Captain Shortwave

[Frosty.]

Well it's a hell of a lot more interesting for coldies now than the recent blowtorch conditions and I think there is increasing potential for wintry weather next week, especially further NE.

[northwestsnow]

Very happy with the evening runs. UKMO would i feel produce some snow on the northern flank of the diving low and its setup for a colder evolution.GFS doesn't produce the goods even with a hugely negative AO -

I remain positive that things are changing for the better

[Methuselah]

1 minute ago, Captain Shortwave said:

I have to congratulate the GFS there, for how much blocking throughout the run the GFS brings pretty much no snow to any low lying areas across the UK. That is some achievement. Some parts of the run are very very ugly with frequent bursts of heavy rain which will do no good for the areas currently experiencing flooding, the risk could also spread considering the rain will be much more widespread under this set up.

 

The UKMO is good and for a time the GEM is better

 

The GEM then goes wrong given a poor result betwen the two areas of cold pooling to the west and east of the UK

It turns into another rain-fest.

The models are never going to verify very well given these unpredictable pools of very cold and unstable air. There is still the chance of white-out conditions developing if things go well but there is so much risk and so much that could go wrong which means skis would be replaced by canoes.

 

Having looked at those charts, my guess would be for a rather unpredictable mixture of heavy rain and sleet, with snow mainly on hills, and fast-moving lows with associated warm sectors...A right old kitchen-sink job, in other words...

[Skullzrulerz]

Just been reading through just now and i must say and newbies may agree with me on this but how come the gfs's latest run theres people saying cold,snow and others saying rain and wind????

Even I'm confused right now what to think about the GFS??? at least it no blowtorch lol..

UKMO is great for cold fans i add..

But im not getting myself excited over one run/set..as a cold/neutral fan i would love to see cold and snow but at the same time as a reader its very confusing at the moment to understand some people posts i say again some with cold  all over just as much with rain-feast as well.

I think i stay on the fence for the time being  

[fromey]

7 minutes ago, Ed Stone said:

Having looked at those charts, my guess would be for a rather unpredictable mixture of heavy rain and sleet, with snow mainly on hills, and fast-moving lows with associated warm sectors...A right old kitchen-sink job, in other words...

Kitchen sink would be the correct assumption at the moment, but with the chaos going on up in the atmosphere no model is going to have this nailed, the zonal winds are expected to drop off dramatically and with also high flux activity expect a lot more changes to come

 

fromey 

Edited December 29, 2015 by fromey

[knocker]

3 minutes ago, Skulltheruler said:

Just been reading through just now and i must say and newbies may agree with me on this but how come the gfs's latest run theres people saying cold,snow and others saying rain and wind????

Even I'm confused right now what to think about the GFS??? at least it no blowtorch lol..

UKMO is great for cold fans i add..

But im not getting myself excited over one run/set..as a cold/neutral fan i would love to see cold and snow but at the same time as a reader its very confusing at the moment to understand some people posts i say again some with cold  all over just as much with rain-feast as well.

I think i stay on the fence for the time being  

As an overview the gfs is showing an Atlantic dominated scenario with bouts of wind and rain traversing the UK, powered by a strong jet stream, with temps around average, maybe even a little above for much of the time. There is no other way of viewing it unless you are wearing snow goggles.

[Mucka]

Warning, RAMP AHEAD!

Looking through GFS ensembles there is definitely some improvement there, still mixed, but trending very much the right way.

Indeed some runs make UKMO look like a mild ramp.

 

Will attach the short graphs to this post for NE England to see where we are.

EDIT

GFS short ensembles NE England

 

 

Can't say as any big improvement shows up there tbh but nice to see my ramp P19 get beat LOL

They are honestly better though overall re NH pressure profile, nothing really frigid but temps start dropping to around 3C from the 4th.

Edited December 29, 2015 by Mucka

[BLAST FROM THE PAST]

37 minutes ago, Weather Boy said:

Taking that chart literally, would it not mean rain for the SW 1/3 of the country i.e. south coast, S Wales and all of the SW?  They would be in a mild sector would they not?

Unless I am mistaken, I have yet to see any op chart that would given nationwide (or even near nationwide) snow?

I note that METO still very cautious, only conceding a low probability of a cold spell at a much longer time spell than these charts.

WB

Yes but one must look at the bigger development on this run and how that snow already falling in N and NE and Scotland would move south and extend to pretty much most if not all.  I'll try and run through it.

T72, 1045 HP to NE centred east of Sweden.  SSW flow NORTH of Scotland with LP southern half Greenland AND slight finger of a ridge to north half of Greenland.  Deep LP on SW approach UK...a nice approach to bump into a block developing to NE. 

t96 Block to NE has backed WEST.  LP to our SW has bumped into block and is negatively tilting and SE flow in place.  That will not go further NE.  Interesting second strong LP approaching for WSW.  LP to Southern Greenland disrupting and isobars north of Scotland now from S.  Shows block to NE asserting itself.

T120, Greenland HP finger now more of a fat thumb, LP southern Greenland now an LP to SW tip. Second LP from our WSW I mentioned now with the other, negative tilt still in place with strong SE flow.  Pressure lowered to Italy / SE Europe enticing our LP to slide towards that region.  That LP to our west is still fairly rounded though.

 

Our LP is now sausaging and sliding SE, crucially LP to SW tip of Greenland hasn't budged and a ridge in Atlantic towards Greenland is Building to block the Atlantic .  Our LP will slide and a NE and N flow would envelope all of the UK from there.  A great run.....BUT it is one model and it stlll is an IF re detail ahead. Nice to see though

 

BFTP

Edited December 29, 2015 by BLAST FROM THE PAST

[Daniel*]

Noticing a trend of +ve heights wanting to cross over to Greenland, potential retrogression of Kara Sea block to Greenland in the longer term?

 Again a very wet or very snow picture is on the cards for the northern half of the country next week. I currently favour the latter 70:30, mirroring a similar story to Nov/Dec 2009...

Edited December 29, 2015 by Daniel*

[fergieweather]

4 minutes ago, knocker said:

As an overview the gfs is showing an Atlantic dominated scenario with bouts of wind and rain traversing the UK, powered by a strong jet stream, with temps around average, maybe even a little above for much of the time. There is no other way of viewing it unless you are wearing snow goggles.

Yes, still caution advised on where this ultimately travels.  As UKMO note (in briefing earlier today about this unfolding situation early Jan), the dichotomy of GFS versus other deterministic models is all the more eye-catching this occasion because - as Exeter puts it - "....it (GFS) is often the least progressive of the main models...".

(Emphasis on 'least')!! 

[nick sussex]

4 minutes ago, fergieweather said:

Yes, still caution advised on where this ultimately travels.  As UKMO note (in briefing earlier today about this unfolding situation early Jan), the dichotomy of GFS versus other deterministic models is all the more eye-catching this occasion because - as Exeter puts it - "....it (GFS) is often the least progressive of the main models...".

(Emphasis on 'least')!!

I'm not sure if you were being ironic. The GFS is often criticized by NCEP for being too flat and progressive, I've seen them make note of that many times especially in their state forecasts and especially for the GEFS.

Edited December 29, 2015 by nick sussex

[Mucka]

4 minutes ago, fergieweather said:

Yes, still caution advised on where this ultimately travels.  As UKMO note (in briefing earlier today about this unfolding situation early Jan), the dichotomy of GFS versus other deterministic models is all the more eye-catching this occasion because - as Exeter puts it - "....it (GFS) is often the least progressive of the main models...".

(Emphasis on 'least')!! 

That's a surprise. I think the general sentiment portrayed on this forum is GFS is among the most progressive.

We have seen verification stats that show GFS is behind the Euros, do the MetO give any extra weight to the Euros when they are similar but divergent from GFS?