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phil nw.

Model Output Discussion 17th Dec.2013-12z onwards.

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It will feel cold in the wind tomorrow from the midlands northwards.

 

Posted Image

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Certainly a lot of flip-flopping around among the ensembles with a  bit of everything on offer.

All still quite tentative so it's case of recognising that and willing the ensembles ever colder. Posted Image

 

GFS ens: NW England temp

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=240&y=39&run=12&runpara=0&type=3&ext=1

 

SE England 850's

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=291&y=124&run=12&runpara=0&type=0&ext=1

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Some subtle hints of a New Year pattern change, but it's going to take its time.First, the 500mb flow is fascinating:Posted Imagehemi1_00hr23122013.pngThe most remarkable feature is the sheer strength of the flow across the Atlantic around the base of the upper low heading towards us, quite rare to see such intensity I think. There are changes upstream as the E Pacific ridge fades and once again Pacific systems are heading SE to re-invigorate the upper trough over E USA/Canada. This suggests, on the face of it, more of the same with the jet continuing to propagate in our direction, with the relentless LPs coming with it.However, note the 500mb high near the Pole that's been there for a few days. It may not look much but if it sticks around, once the pressure field across the Atlantic starts to slacken off, it may just hint at HP building. I mentioned this possibility before, but the ferocity of the jet has obliterated any chance of any blocking pattern forming, let alone persisting so far. But in my experience at least, stormy mobile patterns of this intensity cannot sustain themselves for THAT long.So I am sticking with the story I have been telling for a while now, of LP and the upper vortex sinking slowly S and an accompanying flow of colder air, gradually followed by rising pressure to the N and NE.Well, my very best wishes to you all for a good Christmas and my great thanks for so many of you who have added "Like" to my posts, it is most kind and I appreciate it a lot.I hope Santa brings you everything you want!OMM

Have a peaceful one OMM and i have the same belief.

Edited by winterof79

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Well the ECM is possibly backing something tonight.

Unfortunately it's most likely the metoffice outlook.

Posted Image

Weak Atlantic ridge which will edge across the south of the UK at days 9 and 10 bringing some drier weather most likely.

Could see something wintry from the preceding north westerly though.

That Arctic high is heading toward Siberia, not at the same rate as the previous output but it's the same direction.

Day 10 - lols standard. ECM you get an XBox made of coal. (warning do not overheat)

Edited by Captain shortwave

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Have a peaceful one OMM and i have the same belief.

Thanks winterof79! You too.

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Some wintry weather for new years eve? the 850's certainly look low enough

 

Posted ImagePosted Image

 

2014 starts with less cold air moving into the west

 

Posted ImagePosted Image

 

t240 ends with another low maybe a trend to something colder down the line?

 

Posted ImagePosted Image

Edited by Summer Sun

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Well the ECM is possibly backing something tonight.

Unfortunately it's most likely the metoffice outlook.

Posted Image

Weak Atlantic ridge which will edge across the south of the UK at days 9 and 10 bringing some drier weather most likely.

Could see something wintry from the preceding north westerly though.

That Arctic high is heading toward Siberia, not at the same rate as the previous output but it's the same direction.

Day 10 - lols standard. ECM you get an XBox made of coal. (warning do not overheat)

 

 

Yes, ECM is a rinse and repeat of the current pattern i.e largely zonal and very unsettled - no significant cold/snow as per Met Office's update.

 

Maybe the strat warming will start making an influence on the deterministic model runs over the next few days. Time will tell, but things, though better than a few days ago, are still pretty poor for deep cold.

Edited by mulzy

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Well at least the ECM and GFS agree on the pattern over the ne USA at T240hrs. Theres an awful lot going on in the ECM viewed from the NH , it does look rather incoherent!

 

I think it will still come down to how much if any trough disruption we see around the T240hrs mark in the mid Atlantic.

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The difference between the ECM op and GFS is the Greenland High, a pivotal player for the flow to the UK.

ECM mutes that packet of heights. T96: post-14819-0-32854500-1387825729_thumb.g The GFS mean: post-14819-0-37839900-1387825774_thumb.p

Much higher anomaly. That has a downstream effect on the trigger low; the GFS channels the energy SE, between the GH and the AH and that keeps the LP system within the jet stream, that in turn pushes the trough south, allowing the trough to fill and amplify the pattern, rinse and repeat by the next low. Whilst the ECM low gets sent east and flattens the pattern.

ECM does not pump up the GH till T240, to 1020mb and that sends the next low on a more southerly direction, (presumably) getting the troughing, but much later:

post-14819-0-11900700-1387826151_thumb.g

Out of the GEFS members most have 1020 to 1025 for the GH, about 20% have 1015, but none have the ECM 1010.

So FI starts as early as T96 and we will have to wait to see who has modelled the GH correctly. I am not yet convinced ECM is on the right track.

Edited by i'm dreaming of...

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The difference between the ECM op and GFS is the Greenland High, a pivotal player for the flow to the UK.

 

ECM mutes that packet of heights. T96: Posted ImageECH1-96.gif The GFS mean: Posted Imagegensnh-21-1-96.png

 

Much higher anomaly. That has a downstream effect on the trigger low; the GFS channels the energy SE, between the GH and the AH and that keeps the LP system within the jet stream, that in turn pushes the trough south, allowing the trough to fill and amplify the pattern, rinse and repeat by the next low.

 

ECM does not pump up the GH till T240, to 1020mb and that sends the next low on a more southerly direction, (presumably) getting the troughing, but much later:

 

Posted ImageECH1-240 (1).gif

 

Out of the GEFS members most have 1020 to 1025 for the GH, about 20% have 1015, but none have the ECM 1010.

 

So FI starts as early as T96 and we will have to wait to see who has modelled the GH correctly.  I am not yet convinced ECM is on the right track.

Agree with that.I said 144z was FI earlier today but maybe even earlier as you say.

The trend is downward out east

http://cdn.nwstatic.co.uk/ensimages/ens.20131223/12/t850Moscow.png

http://cdn.nwstatic.co.uk/ensimages/ens.20131223/12/t850Berlin.png

 

Make what you will over a pressure rise to the north as yet

http://cdn.nwstatic.co.uk/ensimages/ens.20131223/12/prmslReyjavic.png

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The difference between the ECM op and GFS is the Greenland High, a pivotal player for the flow to the UK.

ECM mutes that packet of heights. T96: Posted ImageECH1-96.gif The GFS mean: Posted Imagegensnh-21-1-96.png

Much higher anomaly. That has a downstream effect on the trigger low; the GFS channels the energy SE, between the GH and the AH and that keeps the LP system within the jet stream, that in turn pushes the trough south, allowing the trough to fill and amplify the pattern, rinse and repeat by the next low. Whilst the ECM low gets sent east and flattens the pattern.

ECM does not pump up the GH till T240, to 1020mb and that sends the next low on a more southerly direction, (presumably) getting the troughing, but much later:

Posted ImageECH1-240 (1).gif

Out of the GEFS members most have 1020 to 1025 for the GH, about 20% have 1015, but none have the ECM 1010.

So FI starts as early as T96 and we will have to wait to see who has modelled the GH correctly. I am not yet convinced ECM is on the right track.

Normally you would expect the ECM to lead the way with height rises to our N/NE, but over these last few weeks it's been pretty bad by it's own high standards. Are we seeing the GFS leading the way again or will the ECM gain some much needed kudos, my money is on a evolution similar to the GFS as ever though time will tell.

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i' do beleave a patern change is a foot lot of the ends starting to show that also the ao and nao r going negrtiv. What's mor the strat showing signs of warming and looking at the strat thread it's looking good for jan. Seasons greetings to every1 and all at netweather and a snowy newyear.

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Good evening from a very stormy West Country. Here is the latest look at the midday outputs from the NWP output for today Monday December 23rd 2013.

 

All output tonight shows a very intense depression West of the Hebrides with some exceptionally low central pressure readings over the next 12-24 hours as its is shown to move gently North. The spell of torrential rain and severe gales continues across Southern Britain for another 6-9 hours before a clearance from the West later in the night sees wind speeds fall and the rain turn more showery as it turns somewhat colder. In the far NW storm force winds for a time later tonight and at first tomorrow are possible.  All areas are shown to see a windy day tomorrow as the Low still has total influence over all areas tomorrow with a mix of sunshine and squally showers for all. Through Christmas day and Boxing Day the weather relaxes somewhat in a sunshine and showery mix with some welcome relief from strong winds for most. By Friday a new intense Low moves NE close to Western Ireland deepening explosively and returning rain and severe gales once more to all areas through the course of the day. the weekend then becomes rather colder and showery again in a blustery Westerly flow.

 

GFS then shows a continuation of wet and stormy conditions through the period from the weekend and over the New Year with continued flooding and high wind speeds still very newsworthy at times. Once into the New Year though still very changeable and often wet the weather becomes less stormy and steadily colder at times with some sleet or snow featuring across the UK and not always just over the hills.

 

UKMO tonight shows Sundays chart with yet another rapidly deepening depression moving NE close to Northern Ireland with severe gales renewed over Southern Britain and heavy, persistent rain sweeping NE to England and Wales through the day.

 

GEM tonight shows a barrage of Low pressure and strong winds across the UK on the run up to the New Year and some way beyond with an awful lot of rain and periods of very strong winds the main ingredients of the weather with academically average temperatures throughout.

 

NAVGEM too shows no let up in the windy and very wet weather at times from Christmas out to New Years Eve at least.

 

ECM also shows very changeable and often wet and windy weather well into the New Year though the intensity of the wind may reduce somewhat as we move into 2014.

 

The GFS Ensembles show very changeable conditions continuing throughout with wet weather at times for all. The very worst of the rain may lessen with time. The colder weather that develops from the operational late in the run is not well supported by other members of the ensemble group.

 

The Jet Stream continues to power Eastward over the Atlantic and around the British Isles throughout the run with the usual oscillating pattern North then South very indicative of very changeable and stormy weather.

 

In Summary there is still a lot of support for a lot more very strong winds and heavy rain for a good while yet before things improve somewhat. It is unlikely that any improvement of note in the current pattern will take place this side of the New Year and with a very strong Jet Stream in conjunction with stark temperature contrasts over the States showing little signs of relenting the pattern could well last out towards the middle of January before any significant change arrives.

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Looking at the models overall a trend to colder conditions into January. The ECM De Bilt ensembles still look unsettled with the main clustering indicating cold but not very cold conditions for that region.

 

The jet is likely to edge further south helped by some forcing from higher pressure towards the Arctic, I think theres still an opportunity around day ten to see some trough disruption further west with some ridging over eastern Greenland directing the jet in more nw/se, possibilities in this case a chance for some snow on the eastern flank of any low running in towards the UK.

 

I'm not sure a HLB Greenland high scenario is likely at the moment, more likely some weakish pressure rises able to deflect the weaker jet as zonal winds decrease in the strat.

 

This does still give the opportunity for something more wintry UK wide rather than just for higher ground, its more a slow transition here than a sudden shift in pattern, day ten though is where I'd be looking especially to see whether we do get some trough disruption to the west.

Edited by nick sussex

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ecm extended continues with the theme of dropping lower heights to our south through week 2.  tbh. the gfs op low res output from the 12z looks a pretty good representation, though possibly a tad too far east if i'm going to be picky.  the jet sinking ever south which i presume, increases the chances of the secondary lows heading nw/se with snowfall on their eastern flanks. i presume this is what C was referring to earlier.

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Scandy High!!!! And jet stream into North Africa!!

Edited by Ali1977

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Have a feeling the Scandi high of the 18z is a bit of a red herring and the 12z output will be closer to reality but who knows?

I suppose it is better to get mixed signals than just a flat zonal signal either way.

January's weather up for grabs it seems.

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Explain I am trying to learn ????

At this time of year a Scandi high can bring cold/snowy weather to the UK via easterly winds. In this instance the flow is not that cold with upper temperature (850) around 0, these need to be -5 or lower to avoid too much moderation over the north sea. Something to key an eye on though Feno13 as we head through winter.This is a very good example of what a Scand high in the right position can deliver to the uk.http://www.wetterzentrale.de/pics/archive/ra/1991/Rrea00119910208.gif Edited by Grimsby Snow Lover

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 Explain I am trying to learn ????

There is a high pressure sat over Scandy at 264 Hours on the latest run, unfortunately it then moved west into Russia, stopping potential eastily from forming...

 

All in FI though, so very unlikely to be correct.

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Explain I am trying to learn ????

Nothing to be excited about here, move along :-)Its a more of a Russian high than a scandi one, which would result in cool days at ground level but with a warm upper air profile. In essence its a bad pattern if your looking for cold and snow. It's all nonsense of course as if you run through the run you can see how everything just changes as it hits the post 192 hours low res part of the run. Jason Edited by Jason M

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All that work with a pressure build towrds scan and the 850s are rank!never really gets in the correct position either way and way in fi.tbh the run looks odd post the 180 hr mark and just blows up once the low goes threw greenland given the weaker heights there on the 18z compared to the 12z.Very minor positions of the troughing totally alter the run thus i guess its wait and see

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All that work with a pressure build towrds scan and the 850s are rank!never really gets in the correct position either way and way in fi.tbh the run looks odd post the 180 hr mark and just blows up once the low goes threw greenland given the weaker heights there on the 18z compared to the 12z.Very minor positions of the troughing totally alter the run thus i guess its wait and see

Looking at the pattern it's going to be very difficult to get any useful 850s into the mix. Any heights will need perfect positioning as there is nothing but thousands of miles of warmth to our east (at 850 level). So far this winter is proving to be a very mild one indeed for much of NW Europe and Western Russia. Logically mainland Europe will get its turn at some point although getting that to back west come the time is always the tough part. Edited by Jason M

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