Model Output Discussion 18/11/2012 12Z onwards

[cold snap]

Silence speaks volumes never thought I write this but at 168 it's worse than the gfs if it blocking your after

Edited November 18, 2012 by cold snap

[No Balls Like Snow Balls]

Silence speaks volumes never thought I write this but at 168 it's worse than the gfs if it blocking your after

I think the silence is down to most people comment at the end of the run rather than every frame

Edited November 18, 2012 by No balls like Snow Balls

[chionomaniac]

Well at T+192, the ECM shows a most wonderful omega block. Sadly it is on the Pacific side.

Edit: T+216 shows energy and WAA over western Greenland.

Edited November 18, 2012 by chionomaniac

[MR EXTREMES]

Interesting charts of the ECM at 120h compared to the same one in the yesterday's run. Highs building much norther

Yesterday

Not looking good everything being pushed east and to far north.

Still very uncertain but nothing to above average temperature wise.

Today

[Jonan92]

It shows now a northerly

[Methuselah]

After the 06Z, I said this:

'From looking through the past few GFS runs, I'm even more convinced that JH will be proved right, in that our first outbreak of really cold weather will come from the north or north-west; even though transient episodes of easterly or north-easterly winds may well occur, as troughs drift around and change shape over the near continent...'

Would I have said the same thing following the 12Z? I think not! A fine example of what can happen when one bases a forecast on a single run...

[The Eagle]

ECM is not too bad. Gradually cooler but nothing spectacular.

[SMU]

Evening- we are going to run out of hens teeth soon-

The models today have been ok. the ECM is ok just slow

back to my death bed with my 24 hour bug

[nick sussex]

The ECM upto 192hrs is very similar to the mornings 00hrs run, it gets to some interest after that eventually but its painful to watch.

Realistically so much has to go right here especially with that Azores high lurking that the chances of success just taking this run at face value is IMO close to zero.

The margins are so narrow here that this run has more pitfalls than many colder evolutions I've seen on the net, for this reason we can only hope that the models plot a more straightforward evolution.

There are some more positives upstream and with the continued Aleutian ridge but overall the ECM picks the most nerve shredding route to cold, indeed if we had sit through this evolution counting down the days I fear for the sanity of some members!

[weather eater]

The ECM upto 192hrs is very similar to the mornings 00hrs run, it gets to some interest after that eventually but its painful to watch.

Realistically so much has to go right here especially with that Azores high lurking that the chances of success just taking this run at face value is IMO close to zero.

The margins are so narrow here that this run has more pitfalls than many colder evolutions I've seen on the net, for this reason we can only hope that the models plot a more straightforward evolution.

There are some more positives upstream and with the continued Aleutian ridge but overall the ECM picks the most nerve shredding route to cold, indeed if we had sit through this evolution counting down the days I fear for the sanity of some members!

Curiously at 240hrs it’s not a million miles away from the 12z GFS at the same point.

Edited November 18, 2012 by weather eater

[Gibby]

Good evening. Here is the Sunday evening look at the 12zs from the big three for Sunday November 18th 2012.

All models continue to show a very changeable week to come. As Low pressure becomes established to the NW of the UK with wind and rain in abundance over the next 5-6 days in strong SW winds and temperatures generally on the mild side. There will be some drier and brighter interludes between the rain bands and the SE will probably end up not having too much rain while as usual in these situations the North and West see heavy rain regularly.

GFS then takes us through next weekend taking the Low pressure trough East over the UK and bringing fresher and cooler weather briefly with some showers in the West. Early in the following week the weather remains changeable with further rain at times. Pressure builds down from the North by midweek with cold and drier weather sinking down over the UK with frost and fog at night. After a few days winds strengthen from the East in the South pulling rather cold and chilly conditions across the south of the UK from the East with some rain or perhaps sleet in places. In the North things would probably stay dry and rather cold. By the weekend a strong SE flow develops ahead of a deep Atlantic low pressure pushing a trough slowly North over Britain. In the process a band of rain and sleet, turning to transitory snow as it moves further North would occur over the weekend before generally milder weather spreads back North to most areas behind it by the end of the run.

The GFS Ensembles show the continuing downward trend in uppers over the coming two weeks. The operational was a mild outlier in the South at the end. Rainfall becomes more of a rarity in the latter end of the run in the South. It must be noted though that the lowering of the uppers are skewed by a rise in the long term mean at the end of the period hence the apparent larger than real fall in relative uppers. Nevertheless, the trend is the right way for cold lovers.

The Jet Stream continues to track across the UK in the coming days. As the Low pressure trough moves East at the end of the week the flow buckles South of the UK before ridging North in the Atlantic in a week's time.

UKMO for midday on Saturday shows low pressure East of Iceland and a trough down the North Sea. A slack Westerly flow is shown over the UK with scattered showers in near normal temperatures.

ECM shows a transient ridge across the UK on Saturday before Low pressure crosses on Sunday with rain and wind sweeping East followed by colder and more showery conditions to start the new week with some wintry showers over Northern hills. As the model moves further into the week winds turn to the North in response to a rise of pressure South of Iceland with further wintry showers likely, reaching the higher ground of the South too later. The run ends with the High toppling SE towards Scotland setting up a cold and raw NE flow over England with some rain or sleet in the SE while the North and West become cold and frosty.

In Summary the details change but the pattern remains the same with a mild and unsettled week to come before next weekend sees colder but still changeable conditions. Thereafter the details are irrelevant but the one common factor is the continuation shared between the models of the desire to introduce somewhat colder and drier conditions to our shores with the chance of frost and fog increasing as well as the likelihood of some wintry showers.

[phil nw.]

Curiously at 240hrs it’s not a million miles away from the 12z GFS at the same point.

Yes i was just about to say the same thing WE.

There`s some trend now for pressure building in week 2 as the first attempt at ridging in the Atlantic semi-topples and forms a high near the north of the UK.

A cooler surface and some frost would be likely.

[nick sussex]

Curiously at 240hrs it’s not a million miles away from the 12z GFS at the same point.

Yes they both get there eventually but its far too exhausting!

Indeed given some of the previous winter dramas in here it will be like last netweather member standing, whilst these hardy members are out sledging the rest will be treated for nervous exhaustion!

I have a grading system for cold evolutions and this has sirens and red flashing lights!

Why can't we just order the BOM for tomorrow at least that removes the troughing in good time, overall I'd say the UKMO at 144hrs is the best of the bigger models for that timeframe.

Because the heights aren't so low to the north we might see a quicker evolution to cold and not have to put up with the masochistic GFS and ECM!

[cold snap]

Yes the ukmo the pick of the bunch maybe because it want go further than 144 thankfully couldn't take another slow evolution

[ICETAB]

Yes the ukmo the pick of the bunch maybe because it want go further than 144 thankfully couldn't take another slow evolution

JMA looks like the pick of the bunch to me. I'm sure we will see colder runs in the near future...

[weather eater]

Could be just coincidence I expect the 19z to show something else again, we shall see.

Edited November 18, 2012 by weather eater

[Cheese Rice]

GEM looks decent

[london-snow]

Nothing has really changed again for me today..

Evolution is that there is a increasing signal for cold conditions towards the end of this month. However whether this means a snowy cold spell or a settled spell is very much still up for debate and will be until we see agreement across the board we are none the wiser so as for trends or comments or forecasts stating that it will be settled ect i would not bank on it as its all about the positioning which wont be clear for a little while yet.

Run of the day for me is the ukmo as it shows the cleanest route to get cold in to the uk.

[ANYWEATHER]

Really cant understand the negative thoughts on here for those who want a cold spell! The models are showing the weather getting colder from next weekend onwards, the trend is there, but how cold, how much snow, frost and the longevity of the cold spell remains uncertain. I would stick my neck out and say the computermodels are underestimating the projected cold. As ever time will tell, but for the coldies , there is alot to get excited about.....!

[Mark Neal.]

Could be just coincidence I expect the 19z to show something else again, we shall see.

Your be waiting a long time, its the 18z

Overall it seems we are no closer to knowing what will happen for last week of November, and looks like it is going to be a while until that happens.

This week looks very unsettled and windy to begin with, with a better mid week showing in the models. West always in the more heavy rain, drier futher east.

[Timmytour]

Saw the Country File forecast and what they showed for the positiion on thursday looked quite a bit different to what the GFS 12z is showing. I guess such differences over a short period of time grow into more dramatic differences over a ten day period. To me the GFS is not ruling out the introduction of a Siberian High further west....but one with it's teeth not yet developed. I still remain optimistic that with the Med low and the way what seem to be vigorous Atlantic lows run up against a brick wall, future runs are going to promote more activity coming at us from the east which eventually evolves into a real taste of winter

[weather eater]

JMA looks like the pick of the bunch to me. I'm sure we will see colder runs in the near future...

Very nice, but it looks too simplistic, especially the transition from 144hrs to 168hrs. And its evolution from120hrs to 144hrs is very out of kilter with the big three, I don’t buy it unfortunately.

[weather eater]

Your be waiting a long time, its the 18z

Overall it seems we are no closer to knowing what will happen for last week of November, and looks like it is going to be a while until that happens.

This week looks very unsettled and windy to begin with, with a better mid week showing in the models. West always in the more heavy rain, drier futher east.

LOL spare me I only missed by one key

[Alan Medlock Valley]

Really cant understand the negative thoughts on here for those who want a cold spell! The models are showing the weather getting colder from next weekend onwards, the trend is there, but how cold, how much snow, frost and the longevity of the cold spell remains uncertain. I would stick my neck out and say the computermodels are underestimating the projected cold. As ever time will tell, but for the coldies , there is alot to get excited about.....!

You know what it's like some people are never satisfied unless we get 20 foot drifts . But really I think it's probably a case of us being spoilt over the past 3 years in terms of the depth of cold, so people will look for the possibility of deep cold in the models.

[london-snow]

Very nice, but it looks too simplistic, especially the transition from 144hrs to 168hrs. And its evolution from120hrs to 144hrs is very out of kilter with the big three, I don’t buy it unfortunately.

That's what i want w-e SIMPLICITY otherwise dr nicks prozac pills will be coming to a pc near you lol...

The thing here also in this type of situation is can we really dismiss every model?

I dont think we can as at the moment there is no clear agreement from the so called big three. Yes the general idea is there however there is still strong disagreement in the type of weather that we will receive going forward.

.