Winter Model Discussion 18Z 5/2/13 onwards.

[chionomaniac]

so in effect they are pretty much meaningless to what happens on the ground given the number of shortwaves which plague at every cold opprtunity!

Only if you don't know how to interpret them properly.

If you do, then you will get the long wave pattern correct, which is a great help when determining a the overall surface pressure patterns. Only a fool would try and predict surface conditions from a suggested long wave pattern 10 days out - but a wise man could give likelihoods of certain types of weather and below or above average temperatures. Sadly, suggesting a below average spell at 10-15 days is not good enough for some or others take it that it definitely means snow, but those with the greater understanding of the anomaly charts realise that this is not so and temper their expectations accordingly.

[winterof79]

Shortwave scuppers cold extension. That's it really , if the ECM is correct with the shortwave then the cold ends quickly. Regardless of how strong the Scandi high looks its not much good if it cant advect the cold west and that wont happen with the shortwave from hell on a tour of the Hebrides.

The ECM placing the shortwave there in a sense sums up what has been a frustrating winter for many, so close, so many times but not able to get the pieces of the puzzle to come together.

Earlier a chance of some snow as the low clears and then a brief window of snow showers for the se before it all implodes in a sea of shattered dreams and if onlys as the shortwave waits to phase with the next low.

We can only hope the ECM is wrong with the shortwave because its yet another missed opportunity if that verifies.

Its Wednesday.The output that is being taken as gospel by a few is next Tuesday.People need to get a grip.The following chart should be greeted with open arms.

http://www.meteociel.fr/modeles/ecmwf/runs/2013020612/ECH1-120.GIF?06-0 There will be snow in the lead up to and during this.

There has been snow for us northerners this week too along with thunder and gales.

[weatherguy]

Seems very gloomy in here tonight, but it's important to note that the orientation and direction of any shortwave can and most definitely will move at this range....

Even with the current situation, we still get this which is a damn good chart:

[nick sussex]

Its Wednesday.The output that is being taken as gospel by a few is next Tuesday.People need to get a grip.The following chart should be greeted with open arms.

http://www.meteociel.fr/modeles/ecmwf/runs/2013020612/ECH1-120.GIF?06-0 There will be snow in the lead up to and during this.

There has been snow for us northerners this week too along with thunder and gales.

Yes as I said in my post a chance of snow as the low clears so yes to be welcomed but as for this northerly the BBC keep saying sourced from the Arctic, its been a very underwhelming affair unless you're a mountain goat.

Overall one of the least potent northerlies I have ever seen. Thereafter the models have played with shortwave placements, the UK might get lucky, you never know,however if its the ECM placement then game over.

Edited February 6, 2013 by nick sussex

[SMU]

Evening - a bit of an odd thread tonight- I must say If i hadnt have seen the ECM I would be confused.

Anyway- just a short post tonight-

around 5 days ago it was my expectation that all the models were wrong bar the ECM & they would come into line with the ECM- which they 'generally have' ( this is when everyone inc the MOGREPS didnt fancy it- we must note this)

What I am seeing from Ians snippets is that the MOGREPS & Decider model show an increase in cylonic flow at day 8- 10, this is born out by the ECM op-

It appears in most peoples eyes that this is the beginning of the End, but could just be the ending of the start.

Of course the models will show the atlantic running close & an increase of cyclonic weather, however its how that manifests & what angle the Atlantic comes in - is the key tonight & maybe the models are wrong because at this range they perhaps cant quite see energy going under the block.

Last year the weakness I saw from the ECM was always progging low heights over west scandi- ( yes an ECM weakness )

where it did then push lows to far through

So what do I see from the ECM tonight- well 192 onwards sees the 'apparent' influence of the atlantic pushing in-

However I also see the energy trying to get under the block....

It will only take a slight reditribution of energy & those last 3 charts will look different with snow moving south.

I wouldnt say im convinced the ECM is wrong tonight, maybe 65% of me expect it to be more amplifed come the actual day- hence the small tweaks will look favourable-

Somewhere along the lines of the JMA

http://www.meteociel...modeles/jma.php

Also lastly ECM is further west that UKMO for the weekend-

http://en.vedur.is/p...06_1200_102.png the line here from Essex through the midlands EAST is the potential snow area-

this then moves in EA & the NE-

With a front progged in that locale at 96 the chances are small corrections west of likely so finely balanced for the UK, however as said the spine of the country more at risk than the SW

S

Edited February 6, 2013 by Steve Murr

[Ian Brown]

Thanks Mucka - I started this last night about the easterly on Monday and was jumped by all and sundry.

With regard to the shortwave, yes it's there but essentially the heights are low to the NW anyway and it wouldn't matter in the grand scheme of things - which is a progression to milder Atlantic weather by the middle of next week.

[Richie V]

Lol@ timmytour, ive had a good long break from veiwing any run of any model. Since my last veiwing things certainly look far less sweet if your a coldie, not that I thaught they were in the first place, it seems we have our old freind the good ol shortwave back on the radar!

People need to listen to john holmes on here and learn the 500 anomoly charts. Mabe then there will be less petty tantrums on here when things stop going bobby dazzler! ........ Snow hurricane, that was a joke....right?

Ric

[Ian Brown]

Seems very gloomy in here tonight, but it's important to note that the orientation and direction of any shortwave can and most definitely will move at this range....

Even with the current situation, we still get this which is a damn good chart:

Well it isn't really - all it is is the front clearing South with some snow for the SE as it clears away - it is not a convective snow shower chart.

[winterof79]

It would be essentially dry for most with frontal ppn clearing away. You need a sustained Easterly flow to generate convective showers that will penetrate inland not a few hours of transient Easterly flow.

I'm not with SM that the ECM has suddenly flipped away from cold, some of us have been posting about it moving away from sustained blocking since the weekend with the UK more and more under threat from Atlantic incursions.

Still time for things to change but we need that shortwave out of the way since it now looks likely it has been correctly modelled but that is not the only potential spoiler.

I have been saying that not only do we need to the high to hold against the flow to our NE but we also need more amplification in the pattern behind. This mornings UKMO looked quite good for that and from there we may have got another slider and stayed on the right side of the block but it had little support and looks flatter and faster this evening as does most of the output though it is still the best of a poor bunch for sustained cold.

ECM and GFS have low pressure to the SW of Greenland at 144 - game over from there because even if more energy than currently modelled goes SE and the shortwave doesn't push the block too far East we will still see the cold air squeezed too far East so mostly cold rain although prospects would be better than currently modelled by ECM from there.

We need to see improvements in;

1) The slider (pattern) being moved back west.

2) Residual energy removed or forced further SE under the block (The block to be well aligned and ridging across to Greenland)

3)Better ridging behind the slider and less energy to our NW

On point 1, all the output would benefit from the pattern shifting west with better troughing to our SE, GFS never bought into this initial trough being a significant player in forcing the pattern west and bringing an Easterly flow a la ECM runs of a few days ago which is a part of the reason it never got near the amplification of ECM and HLB though its Easterly (progressive) bias was also telling. UKMO has handled this best but has the advantage of only modelling it at closer range.

On point 2, GFS has the block most poorly aligned with UKMO and ECM in better shape at 144. However ECM models the shortwave to be significant and N of the UK which is not good while UKMO has moved it East toward Scandinavia where it is a little less of nuisance. ECM and GFS have 985mb low pressure to the SW of Greenland at 144 with the Atlantic queuing up behind. Hard to see any cold pattern from there. However UKMO has less energy in that region and along with the pattern to our NE we would more likely see disruption from there. The Azores high is uncomfortably placed but not too far East that would prevent proper undercut if the jet played ball and would likely be displaced west if we got the desired slider. The pattern behind is more amplified than ECM or GFS at 144 so we would likely get a much more promising pattern behind (Better Atlantic ridging) and a reasonable shot at a sustained cold spell. All a bit crystal ball admittedly but I did talk about the diving low scenario of the coming period as far back as January 27th.

That has basically summed up point 3, more amplification behind. ECM and GFS no. UKMO possibly.

So a cold spell developing immediately after the slider is currently looking unlikely based purely on this evenings output but overall UKMO still offers hope and was good this morning, ECM ensembles this morning still had the cold largely hanging on to mid month at least which goes against the last two Operational runs and indeed this mornings was on the mild side of its set. We will have to wait and see if they have moved away from that position this evening, if they have and ECM Op isn't again on the mild side we are really struggling.

It does not take long to drive in convective showers from a meaty easterly wind.The system drops through between 96 hrs and 144.Even a slack floe will give heavy showers in that period.

[cheeky_monkey]

im still surprised not many people look at what is happening upstream across N America and the eastern Pacific..that big high pressure cell across Western Canada and the States just doesn't want to go anywhere this is keeping low pressure entrenched across Alaska and the Canadian Arctic..this High pressure needs to be pulled up into Alaska and the arctic for any shot of prolonged cold across Europe..this scenario we have now is what scuppered the last cold spell back in January..also the same set up occurred last January and February and the UK missed out on the cold then because of it..IMO

[ANYWEATHER]

For Heavens Sake Folks,Short waves, long waves ,WarmSectors and the like the weather does not have any regard to computer models forecasts. Its always been [generally] a knife edge situation regarding forecasting snow in the uk, this weekend will undoubtedly hold some BIG surprises during late Sunday/Early Monday regarding snowfall.....IMPOSSIBLE to forecast but with this situation Im sure some folk will be happy!!!

Edited February 6, 2013 by ANYWEATHER

[legritter]

I cant check ECM on other sites as iv ongoing computer problem but going by all of todays data and tonights posted charts i will say this ,we have an exceptionall weather period coming up sunday onwards .all the ingredients for a possible real wintry mix . and it wouldnt surprise me if favoured locations dont get substantial snowfall .it could come from the low running south or s east further west to start or ,moving south across centre of country ,pulling in colder air as it slips south . but of course there is still the possibility of it keeping to far west .a december 26th 1963 would do me .my Mother telling me off for continuously messing up her curtains whilst lamp post watching .certainly a good time for FAX charts over coming days .And please as i mentioned the other day ,this is one of the best weather forums in the WORLD ,but a few prams are causing havoc , meteorology today is in my opinion 30percent more accurate today than 30yrs ago but still in its infancy ,we pull the modells apart but imagine being in a plane at 36,000 ft going the circumference of our planet ,look down and all you see as got to be modelled by a computer ,and above, and all that energy from our star ,and ocean ,enjoy the weather ,catch up later .

[winterof79]

Yes as I said in my post a chance of snow as the low clears so yes to be welcomed but as for this northerly the BBC keep saying sourced from the Arctic, its been a very underwhelming affair unless you're a mountain goat.

Overall one of the least potent northerlies I have ever seen. Thereafter the models have played with shortwave placements, the UK might get lucky, you never know,however if its the ECM placement then game over.

Not aimed at you Nick in particular.It is not a potent northerly agrred but it has just followed a very potent W/N/Westerly

[Gibby]

Good evening. Here is the evening review of the 12z output from GFS, UKMO and ECM for tonight Wednesday February 6th 2013.

All models currently show the UK under a feed of cold Northerly winds following the exit of Low pressure from the East of the UK. The flow is shown to slacken over the coming 24 hours as an occlusion moves slowly East into the UK tomorrow. Overnight sleet and snow showers will continue over Eastern Coastal counties overnight with East Anglia the prime spot. Northern Scotland and the coasts of the West may see some wintry showers too at times overnight. By morning cloud from the occlusion will move in from the West with some rain, sleet and snow moving into the UK tomorrow. As the front decays in situ over Western Britain on Friday a couple of quiet and bright days look likely albeit cold with a little sunshine likely on Saturday. On Sunday a more active trough approaches from the West with the front disrupting as well as forming it's own Low centre somewhere over or biased just to the West of Central England. All areas look at risk of rain which will likely turn to snow with time as the system slides SE into NW Europe and the UK comes under a cold Easterly flow on the North side of the Low on Monday of next week. Amounts of snow range from copious quantities or virtually none at all with the models all showing slightly different variations of positioning of the Low which though small meteorologically speaking have major implications for any one place relative to it.

GFS then shows a slack pressure gradient on Tuesday with a cold and non-descript day before midweek shows another trough pushing East with rain and some snow on its leading edge. This one is shown to make it over to the East of the UK with less cold and drier weather following. Thereafter, a short unsettled spell with rain at times with nearer to normal temperatures is shown before colder weather returns courtesy of High pressure developing this time over Greenland with a very cold and Wintry Northerly based airflow to end the run.

The GFS Ensembles show a continuation of a rather cold group of ensembles coupled with somewhat unsettled weather at times with occasional rain and snowfall. The operational was a cold outlier around the 12th and again around the 17th and 18th otherwise it was reasonably representative of the group when taken as a whole.

The Jet Stream shows the Northerly flow over the UK currently weakening and being replaced by a more NW flow with the axis of the ridging over the Azores High being pushed further SW towards a position just to the west and SW of the UK in a weeks time. The flow is programmed to stay a long way South over Europe around the Southern part of the Med and North Africa.

UKMO for midday on Tuesday shows a cold and slackening Easterly flow over the UK with snow showers likely in the East, especially in the morning. Scotland will see the brightest and driest weather through the day.

ECM tonight shows the Low on Sunday further West than it's counterparts bringing more of the UK under greater risk of snowfall before moving things away quickly SE early next week with the weather becoming less wintry but staying rather cold towards the middle of the week. Later in the run the trend is for milder Atlantic winds coupled with what seems relatively weak and weakening troughs to move across the UK slowly bringing less cold air in on a more West or SW based airflow.

In Summary tonight a cold and potentially wintry spell still looks feasible from tonight's output. True there is not much room for any further Eastern movement of the system from some output to bring anything other than cold rain rather than snow for many later Sunday and Monday though ECM does hold out hope, keeping the disruption and resultant Low pressure far enough West to keep the interest. Longer term there seems enough evidence from tonight that less cold air will stagger in from the West from midweek as winds back West or SW as successive troughs dislodge the cold block to the East of Britain bringing rain in with them and the chance of forward edge snow.

[bluearmy]

As an aside i checked boston on th ecm op for snowfall at the w/end and it shows 60mm precip!!!

If only roger was right for this side of the pond

[nick sussex]

Not aimed at you Nick in particular.It is not a potent northerly agrred but it has just followed a very potent W/N/Westerly

Yes I suppose its at least been great for your ski resorts, just a shame a warmer area of uppers got into the mix.

Apologies if my recent posts sound rather grumpy, a knock on effect of having this hideous cold now for what seems an age and my forum etiquette seems to be descending towards more TOWIE than Downton Abbey!lol

Edited February 6, 2013 by nick sussex

[BLAST FROM THE PAST]

Sorry you had to see that fergie.

See above-the post has gone now.

Fair enough Phil, maybe it should be elsewhere or not at all on the forum. It was no personal attack on Fergie so though I withdraw the comment there's no real need for individual apology because it wasn't personal. I'll keep my 'thoughts' off the forum.

Edited.....moved on.

BFTP

Edited February 6, 2013 by BLAST FROM THE PAST

[ChartViewer]

Yes I suppose its at least been great for your ski resorts, just a shame this warmer area of uppers got into the mix.

Apologies if my recent posts sound rather grumpy, a knock on effect of having this hideous cold now for what seems an age and my forum etiquette seems to be descending towards more TOWIE than Downton Abbey!lol

LOL Nick...youve been calling it spot on as you always have for 5 years....is it as long as that

CMA T120 12Z

[Long haul to mild]

Thanks Mucka - I started this last night about the easterly on Monday and was jumped by all and sundry.

With regard to the shortwave, yes it's there but essentially the heights are low to the NW anyway and it wouldn't matter in the grand scheme of things - which is a progression to milder Atlantic weather by the middle of next week.

I shall respectfully have to disagree with you and Mucka on this point. My area has often benefitted snow-wise from these type of (albeit short-lived) flows in the past. Sure I'd rather have a proper convective long draw Easterly but I can assure you that there are definitely snow showers in these set ups.

[bobbydog]

Yes I suppose its at least been great for your ski resorts, just a shame a warmer area of uppers got into the mix.

Apologies if my recent posts sound rather grumpy, a knock on effect of having this hideous cold now for what seems an age and my forum etiquette seems to be descending towards more TOWIE than Downton Abbey!lol

not the prolonged cold you were hoping for, eh nick?

[weatherguy]

Well it isn't really - all it is is the front clearing South with some snow for the SE as it clears away - it is not a convective snow shower chart.

Would the steep temp gradient over the north sea combined with a strong easterly flow (at that point) not bring lots of showers to eastern areas?

[mountain shadow]

their verification stats as I showed over a 12 month period are not 'shocking' at all, quite impressive actually with them having the correct upper air pattern at 10 sometimes 15 days on 70% of the checks I did.

Fact not supposition that

I would hazard a guess that the 70% being correct is during a flat zonal period with a horizontal jet barreling across the Atlantic.

The thing is, we need those 500mb charts to be guiding us when things aren't as clear cut with split energy and predicted higher latitude blocking.

[ChartViewer]

not the prolonged cold you were hoping for, eh nick?

IMO it is very much yet to be decided re prolonged cold....GP's post, some suggestions all be it in fi are this hasnt run its course re the suggestion of W/SW regime OR heights building into the atlantic...height rises into Greenland.... building re end next week...Very interesting end of offcial winter model watching right now

[Ryan Dutch Weatherman]

Good evening , look BOM 12z , why nobody discus that.

2 slide lows with lot of snow after that a NE flow , Brittain remains cold !

[Ian Brown]

Good evening , look BOM 12z , why nobody discus that.

2 slide lows with lot of snow after that a NE flow , Brittain remains cold !

The BOM is poor model Ryan and not equipped to handle this sort of situation. The writing is on the wall for where we are headed.