Model Output Discussion 1200 hrs 15/11/14

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY SATURDAY NOVEMBER 22ND 2014.

NEXT UPDATE SUNDAY NOVEMBER 23RD 08:00

THE CURRENT GENERAL SITUATION. A slow moving front across the SE of the UK will ebb and flow NW and back SE over the next 24-48hrs. Pressure becomes High over Northern Britain in light winds.

MODELS-2 WEEK HEADLINE  Slowly becoming windier and more changeable later next week and beyond with rain or showers and strong winds at times moving in from the West. Temperatures near or a little above average at times later, especially across the South where a few drier spells are possible too.

THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast shows the weak flow around the UK at present persissting until later in the week when the flow strengthens close to Southern Britain moving further North across the UK later.

GFS OPERATIONAL The GFS operational this morning shows the slack conditions across the UK continue with a front close to the South with  rain clearing by Monday, Then after a few quiet and chilly days a strengthening Southerly wind will bring more rain across from the West later in the week. This then marks a trend to mild SW winds and an alternating pattern of bands of rain follwed by showers under a mobile Atlantic regime developing for all through week 2.

THE GFS PARALLEL RUN The GFS Parallel run is very similar to the operational model in theory and sequence and trend towards a mild and more mobile SW flow with High pressure to the South and Low to the North from the end of next week.

THE GFS ENSEMBLES. The GFS Ensembles also are broadly in line with the above account of proceedings over the coming two weeks with the caveat that this run shows a slightly longer period of disrupting Low pressure sliding SE across the UK into Europe later next week before it then develops the milder and more mobile SW flow the others indicate.

UKMO UKMO today shows very benign conditions giving way to freshening Southerly winds  and rain in from the West later this week as Low pressure slips SE to the West of the UK following the quieter and chillier couple of days early in the week.

THE FAX CHARTS  The Fax Charts continue to show the UK very much in nomansland over the later part of this coming week with troughs mostly slow moving and instrumental around the UK with rain at times in stagnant air.

GEM  GEM this morning too shows a much more mobile pattern developing across the UK in it's latter stages following the quieter and chillier feel to things over the coming 4-5 days though still with rain at times. Winds strengthen from the SW or West later with gales at times around deep Low pressure crossing east over or to the North of the UK delivering temperatures well up near the average for early December.

NAVGEM NAVGEM follows the pack in showing a similar slow transition from the slow moving weather pattern currently with one much more mobile as Low pressure winds up to the North of the UK with strong West or SW winds delivering spells of rain and showers at times in mild conditions overall.

ECM  ECM this morning delivers closer to what I feared yesterday in that a gradual transition to mild West or SW winds around a High pressure belt from Eastern Europe to the Azores develops later as the Jet stream moves North and sets up a pattern that would bring the wetter conditions towards the North and West while all areas see temperatures harmlessly in the average or even mild category at times.

THE ECM ENSEMBLES The Ensemble run shows a familiar pattern of Low to the NW and High to the SW and far East on this morning's run with a mild South or SW flow affecting the UK with frontal troughs close by especially towards the North and West with rain at times as a result.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend still is relatively one of Atlantic Low pressure gradually taking control of the weather with an increasing indication across most output that the Azores High could become more influential towards Southern Britain later.

MY THOUGHTS Scouring the charts this morning to find anything remotely wintry is becoming increasingly difficult as the Atlantic looks like becoming the dominating feature of the weather over the UK once the period of slack and benign pattern over the UK in the next 4-5 days gives way. All models show pressure falling from the NW and some disrupting troughs affecting principally the West of the UK will gradually extnd over to all areas later next week as the Atlantic winds up. Thereafter, it looks like winds will increase markedly across the UK from the West or SW, pressure will rise closer to the South at times and all areas see troughs crossing quickly East from deep Low pressures running East over or to the North of the UK. Fast moving bands of rain and showers look likely for most through Week 2 with some drier spells developing across the South at times. There seems little hope of anything that would suggest anything cold and wintry affecting the UK this side of mid December I'm afraid as the building blocks that are needed to deliver cold to the UK look like receding rather than developing around and over the UK over the period.

[shaky]

Well there's differences as early as 96 hours between ecm and gfs!! Ecm has high slightly further east and the high is not well shaped where as gfs has a well shaped scandi high and is further west! ! Now if i go according to last week ecm had everything further west with the high to the east at 96 hours but gfs had none of it and had everything further east and would you believe it gfs was closer to the mark and ecm was wrong!! Fi stands at 96 hours today! !

[Penrith Snow]

Nothing good is ever going to come of this Russian High which is unable to ridge westwards so I would prefer to see the Atlantic breaking through for a while and then pressure rising in the Atlantic and week or two down the line.

This stalemate is useless where a cool westerly flow leads to at least the possibility of a toppler which can develop into something more interesting.

I maybe shot down for saying it but it's time to press the reset button.

Andy

[Tim Bland]

ECM by day 10 is as bad as it gets for coldies (like me) I hope the strat warming will disrupt that PV!

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=1&type=0&archive=0

[Nick F]

Well there's differences as early as 96 hours between ecm and gfs!! Ecm has high slightly further east and the high is not well shaped where as gfs has a well shaped scandi high and is further west! ! Now if i go according to last week ecm had everything further west with the high to the east at 96 hours but gfs had none of it and had everything further east and would you believe it gfs was closer to the mark and ecm was wrong!! Fi stands at 96 hours today! !

 

Upper (500mb) pattern looks very similar between ECM and GFS, despite the differences with the shape of the HP to the NE of the UK.

 

 

At the end of the day, the shape of a surface high won't make a huge difference to the advance of the Atlantic trough pushing in from the west, though blocking throughout the trop does. But looking at the general trend from models and their ens, it doesn't look like the block will extend it's influence far west enough now to stop the Atlantic trough from pushing in across the UK next week, though the trough's influence may not push into eastern and northeastern Europe due to the block's stronger presence there, with the slow build of cold protected.

 

On another note, hint from GFS op and a few ens members of rapid cyclongensis along the strong westerly jet at the end of next week/next Saturday, the deepening lows getting a bit close for comfort to the UK. Fortunately a long way off to concerned about for now.

[bluearmy]

Extended ECM ens again slowly drop out the euro high 850 anomolys, infact, the uk showing some below av at times! The scandi ridge high anomoly centre in the longer term slowly returning into Finland/nw Russia. The 00z run at T240 had shifted it ne. The Azores anomoly drops away west. The east Canadian low temps subside. what does this tell us? if it right, the push east of the Atlantic is slowly repelled as the block begins to fight back.

incidentally, the control brings in a cold easterly post day 10 via strong euro trough and scandi ridge.

[blizzard81]

You gotta give some evidence for this rather than just a 'feeling'...

This mornings runs confirm the feeling I had last night. This feeling was brought about by the recent massive inter run inconsistency of the ECM operational runs. The GFS P has been much more consistent.

[bluearmy]

Someone might want to post up the NAEFS fi anomolys. These are consistent, looking interesting.

[beng]

http://www.meteociel.fr/modeles/naefs_cartes.php?code=0&ech=240&mode=0&map=1&runpara=

http://www.meteociel.fr/modeles/naefs_cartes.php?code=0&ech=384&mode=0&map=1&runpara=

Just having a look at the NAEFs ensembles to look ahead, no sign at all of our block to the East going anywhere anytime soon - that's a noticeable anomaly at this range still. Suggestion is that winds will begin to come more Easterly than Southerly as we get into early Dec so probably cooler at the surface and drier too at that point.

edit: Nick (BA) I must have read your mind!

Edited November 22, 2014 by beng

[Summer Sun]

The next 4 days or so are looking more seasonal temperature wise according to GFS para with frosts looking increasingly likely tonight for Scotland and Northern Ireland then other parts of the UK from tomorrow night

 

The first frosts start tonight for Scotland and northern Ireland

 

 

Monday sees a widespread frost inland

 

 

Tuesday morning sees temperatures close to 0c but more in the north this time

 

 

By Wednesday night time temps just start to increase Scotland may see a frost depending on cloud but from Wednesday onwards the risk decreases for most

 

[blizzard81]

http://www.meteociel.fr/modeles/naefs_cartes.php?code=0&ech=240&mode=0&map=1&runpara=http://www.meteociel.fr/modeles/naefs_cartes.php?code=0&ech=384&mode=0&map=1&runpara=

Just having a look at the NAEFs ensembles to look ahead, no sign at all of our block to the East going anywhere anytime soon - that's a noticeable anomaly at this range still. Suggestion is that winds will begin to come more Easterly than Southerly as we get into early Dec so probably cooler at the surface and drier too at that point.

edit: Nick (BA) I must have read your mind!

What are the NAEFS ensembles?

[Aceman]

What are the NAEFS ensembles?

http://weather.gc.ca/ensemble/naefs/index_e.html

Was really hard typing it into Google but I got there in the end

[blizzard81]

The block looks weaker on the 06 parallel and the pv to the north west looks irresistible. Conversely, the azores high is less prominent which has got to be a good thing.

http://weather.gc.ca/ensemble/naefs/index_e.html

Was really hard typing it into Google but I got there in the end

Many thanks for that, much appreciated.

[phil nw.]

What are the NAEFS ensembles?

They are the combined outputs of the 3 NA countries blizzared81, ie,USA,Canada and Mexico.

Read all about it here

https://weather.gc.ca/ensemble/naefs/index_e.html

 

i hope that helps.

[blizzard81]

They are the combined outputs of the 3 NA countries blizzared81, ie,USA,Canada and Mexico.

Read all about it here

https://weather.gc.ca/ensemble/naefs/index_e.html

Thank you Phil.

 

i hope that helps.

[Barry12]

Extended ECM ens again slowly drop out the euro high 850 anomolys, infact, the uk showing some below av at times! The scandi ridge high anomoly centre in the longer term slowly returning into Finland/nw Russia. The 00z run at T240 had shifted it ne. The Azores anomoly drops away west. The east Canadian low temps subside. what does this tell us? if it right, the push east of the Atlantic is slowly repelled as the block begins to fight back.

incidentally, the control brings in a cold easterly post day 10 via strong euro trough and scandi ridge.

 

This is why it's important to keep this block, as long as the block is here there is always a chance of getting an Easterly, we have next to no chance of getting an Easterly with a dominant Atlantic. The ECM mean is pretty good as well with the block still strong. I think the ECM 12z will be much better.

 

Edited November 22, 2014 by Barry95

[Cloud 10]

Someone might want to post up the NAEFS fi anomolys. These are consistent, looking interesting.

 

 

Yes,seems to be a signal for a significant weakening of the Canadian/Greenland chunk of the PV,which should take the teeth out of any Atlantic attack.

 

360 hrs away so just something to watch for now.

 

[Summer Sun]

GFS starting to show some snow now

 

Northern Ireland and Scotland next Saturday

 

 

Then again for various parts of the UK on December 1st, 2nd, 3rd, 4th, 5th, 6th & 7th

 

 

 

 

[blizzard81]

Yes,seems to be a signal for a significant weakening of the Canadian/Greenland chunk of the PV,which should take the teeth out of any Atlantic attack.

 

360 hrs away so just something to watch for now.

 

gensnh-21-5-360.pngnaefsnh-1-0-360.png

And the 06z GFS Parallel run agrees with this trend.

[Nick F]

GFS starting to show some snow now

 

Yes, the UK more likely to see any snow in the next few weeks coming from Pm airflows from the west rather than from the east. That's if the Altantic trough gets far enough east.

 

528 dam line spreads from the west across all parts next Saturday on 06z GFS. It's a very crude guide for snow risk and such an airmass from the west would likely see snow limited to the northern mountain tops given long sea track. Mind you, the GFS op over the past week has been toying with the idea, on and off, for snow across the Scottish mountains as early as next Thursday but has on recent runs put back the risk to next weekend, so no guarantees. Give the Scottish ski industry a welcome early start to the season.

Edited November 22, 2014 by Nick F

[Barry12]

And the 06z GFS Parallel run agrees with this trend.

 

Just over an hour ago you were saying the exact opposite?

 

the pv to the north west looks irresistible.

[V for Very Cold]

GFS starting to show some snow now

 

Northern Ireland and Scotland next Saturday

 

 

Then again for various parts of the UK on December 1st, 2nd, 3rd, 4th, 5th, 6th & 7th

 

 

 

well that's just brought a smile to my face... even if it waaaaaaay off - nice to see the hint

[throwoff]

GFS appears to be playing out the block winning, which strikes me as off as it normally seems to overpower the Atlantic

[nick sussex]

Todays output is like waking up on Xmas morning expecting to get your new Playstation and realizing you've hit a time warp and now have to make do with the Binatone tennis game!

 

This probably won't mean a thing to younger members!

 

Overall the ECM once again has led yet another fantasy tour and its now dropped last nights more positive output for coldies and replaced it with yesterday mornings horror show, the upstream pattern flattens out and the PV moves into Greenland.

 

I don't think the French have a term for crud but lets just call it crudé  !!!

 

The ECM ensembles have lost that strong easterly cluster with just a smaller amount hanging onto the precipice!

 

So yesterday mornings ECM was Alien 1, this mornings Alien 2, I really don't want to see a third instalment this evening.

 

As for the other NWP pretty much in the same boat bar the GEM , the problem really is just too much energy spilling eastwards and the flat pattern over the USA and Canada means theres nothing to help pull some of those low heights away.

 

This is Ripley last survivor of the Nostramo signing off......... still waiting to be rescued from this mild void!

Edited November 22, 2014 by nick sussex

[damianslaw]

 ECM longer term operational output today blasting the atlantic through heights to the NE, GFS much less keen, its normally the other way around. Level of certainty is very low at present.

 

Reading a number of thoughts about the winter as a whole based on current background signals and analogues support the present status quo, i.e. early December will see a battle between the atlantic trough and heights to the NE, but as we move through the month the battle will increasingly favour the block. No surprise therefore to see the current output i.e the atlantic will manage to push trough action through to the east over the next couple of weeks, but thereafter will become unstuck and we see the pattern advect back westwards, we then await the trigger to release a much colder outlook. Keep an eye on the strat thread for clues to the potential timing of said trigger.