Model Output Discussion 1200 hrs 15/11/14

[Man With Beard]

Of course it could happen but I cannot see how the chart you show can be seen to support a trough? Perhaps you are seeing the smallish -ve heights suggested as that means. Bear in mind it is an anomaly in itself and that the normal value of the 500mb height in that region is already lowish?

Please don't misunderstand me but the anomalies, I know that is the title of the output, are best ignored unless they are fairly large and coincident with marked troughing or ridging in the predicted contour lines.

Positive anomaly in Atlantic - I suspect an extensive Azores High. Evidence of trough in Iberia - Azores High stops there or ridges over. If it does indeed stop there, we're on the eastern side, meaning our weather comes from somewhere between west and north (so could be NW). Is that reasonable? Perhaps saying troughing to the north was misleading - sorry - my thining was if Azores High is strong then low pressure was likely to be on a higher latitude than ours?

[Jason M]

GEFS out to 180 and overall they are as flat as a pancake left in the fast lane of the M25 during Rush hour. Rock solid agreement tbh between GFS, GEFS, GFS para, ECM, GEM, GEM Ensembles.

Grim really, but let's see what tommorow brings.

[blizzard81]

I wouldn't normally wheel out the NAVGEM and CMA but since its the only thing remotely interesting in the output then desperate times call for desperate measures!

 

The UKMO has that colder dig of air southwards at T120hrs, the GFS and GFS P together with the ECM are reluctant to hold back the troughing upstream and flatter, even the UKMO just offers a short window but you can see from the T120hrs fax chart the sub 528 dam behind the cold front, several troughs shown so if by some miracle this verifies then a chance for some wintry showers especially into Scotland, snow to higher ground:

 

fax120s.gif

 

The support for the UKMO really only comes from the NAVGEM 18hrs and CMA 12hrs output, which is why I put the " desperate times" clause in place !

 

The ECM ensembles at T120hrs have limited support:

 

120.gif

 

It's a shame the models are being so miserly, they could have at least held back the flat tide about to engulf the USA to at least deliver some interest for a few days, anyway enough of my griping!

 

In terms of the ECM ensembles longer term the main cluster still looks on the cold side for De Bilt:

 

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

 

As I'm now really desperately digging for some interest past the mini cold snap of the UKMO( if it verifies), the one straw to clutch from my emergency Christmas Collection is if the Azores high remains displaced with jet running se that something might develop to the ne.

A little surprised to see the modified 120hr fax go with their raw output but I have seen this over the last

few years, only for them to flip on the following night's 96hr chart. Barring something cropping up out of the

blue, I fear it will be quite a long waiting game for us coldies this season.

Edited November 30, 2014 by blizzard81

[Mucka]

So another week and what will the models bring us?

GFS is more amplified this morning in the shorter term at least and even though it is not the best of runs there is a significant shift among its ensembles for the pattern to be further West and more amplified than recent sets in the 4 day range. 

 

GFS op 

 

 

As far as FI is concerned GFS is beginning to paint an unsettled, possible even stormy spell of weather in the 8 to 10 day range as the Western portion of the PV shifts East heralding a period of cool zonal conditions. A lot will depend on how much the AH ridges in but GFS 00z ensembles favour a strong NW flow, so cool, windy and unsettled with snow for high ground at times, especially in the North, perhaps wet snow falling to lower levels in some of the heavier showers as the lows pass to the East, if the ensembles are onto something. We will have to see what develops and how ECM handles things but no sign of blocking on GFS with any real cold, just  seasonal unsettled weather on the cards in a predominantly W/NW flow.

There is just the hint of heights rising to our West in deepest FI once the vortex has shifted West.

 

Edited December 1, 2014 by Mucka

[Duane S.]

First charts of winter official and from where we were 2 weeks ago I would have to say it is all a bit disappointing if looking for signs of a decent cold spell precursors. Little sign of any significant wave2 activity looking ahead, which I am a bit surprised about as I was expecting to be looking at more amplified NH charts for mid-month (December). I see Cohen has commented on the anomalous low pressure system in NW Asia potentially putting the brakes on expected feedback developments (in relation to the SAI), not a good time of year to cut the vortex some slack.

The good news is though, like I said, it is only the FIRST day of winter and everything could change in a few days time!

[Polar Maritime]

I have moved some overnight post's over to the Model/Ramp/Moan thread, Please stick to Model Output Discussion only in here.

 

Thanks, PM. 

Edited December 1, 2014 by Polar Maritime

[Captain Shortwave]

Model output for day 6

ECM

UKMO

GEM

GFS

Parallel

Fairly good agreement here. The next move seems to be how that tropical depression interacts with the jetstream over the Eastern seaboard, whether this keeps the Azores high near the UK or pulls it back allowing more unsettled weather to break through.

 

ECM gives enough amplification for something interesting later on

GEM isn't to far away from this either, so a slither of hope. The one crumb this morning is that next weekend is looking dry and bright for most with night frosts.

Edited December 1, 2014 by Captain shortwave

[Polar Maritime]

Yes Mucka, The GFS  continues as per recent days with a predominantly cool N/W Pm flow. With possible stormy condition for the far North as we move into the new Month/Season. A few miles adjustments N/S of these systems will make all the difference, Which in turn could swing in a Northerly. 

 

Edited December 1, 2014 by Polar Maritime

[knocker]

A quick look at the GFS and P this morning and they are both hinting at what was always a slight concern. That is a  movement south of the Azores HP and the jet moving in conjunction with this allowing the track of depressions to be much nearer the UK. Now given the time frame this is obviously not written in stone.

 

Briefly the (P), the GFS is similar, starts off the run with the Azores HP still exerting influence and lows situated north of the UK  This continues to T156 when the HP becomes flatter allowing a more zonal flow which paves the way for depression to travel across the UK into Denmark. The jet is split out of the US but gathers itself later.

 

The UK thus ends up with a northerly but, alas, it's not that cold but hope springs eternal and the colder air is not far away.

 

Charts courtesy weatherbell

Edited December 1, 2014 by knocker

[Mucka]

Yes Mucka, The GFS  continues as per recent days with a predominantly cool N/W Pm flow. With possible stormy condition for the far North as we move into the new Month/Season. A few miles adjustments N/S of these systems will make all the difference, Which in turn could in a Northerly. 

 

 

Indeed PM, broad agreement now on our weather gradually becoming more unsettled post day 7 with a cool zonal flow developing.

 

 

How cool, how wet and how windy and for how long yet to be determined. 

Edited December 1, 2014 by Mucka

[IDO]

There is no point sugar coating the GEFS FI, it is a massive downgrade with nearly all members showing no inclination towards blocking for mid-month. Around D10 there are ridges and promising signs but the PV goes into overdrive and we head into a very mobile westerly NH pattern. By no means is it a precursor to last Winter but without a trigger there is no sign of an upcoming trop led cold spell. The London temp graph for 850s show the sine wave flow of PM and TM short wave ridges and troughs:

 

 

The mean sits on the seasonal average mark through most of FI.

 

Only one run so we need to see if this has merit. I was hoping the ridge over the western conus would move east and facilitate some heights in our locale. However this morning the jet has turbocharged over the Asian Pacific and over ridden that ridge:

 

Even at T300 the jet is on a mission and is flattening the NH profile: 

 

It is still going strong at D16. This is the wrong trigger, as you need some slack in the upstream flow to allow heights to develop in our region. All really expected, and though Nuri was helpful for background signals for later in the Winter, it has delayed the normal PV building period and it looks like December may be qualified by that synoptic. 

[Duane S.]

Would like to see some better variations on the theme reference that tropical depression but with no real signs of jet bifurication, It would seem destined to leave Cuba, race NNE and phase into the vortex over Greenland. Other than a potentially very snowy PM period for highest elevations in the North as a result that really doesn't help things right now for the rest of us medium term.

[bluearmy]

The polar ridging is the other side of the NH. That means we are at the mercy of the northern arm if it's strong. A sinking upper trough isn't a bad start to winter with an overall weak p/v. yesterday I posted that I thought we would see amplification week 2 somewhere but if not, then the alternative was the sinking upper trough.

Lots more scatter on the ECM week 2 London T2 temps probably reflects fewer 'stagnant' HP dominated scenarios.

We are still a long way from a strong trop Pv so I don't see any reason for coldies to be concerned. few seasoned observers expected the first half of December to bring anything of strong cold interest.

Edited December 1, 2014 by bluearmy

[Ali1977]

So the middle of December after some positive trends now looks like being a damp squib. WAA never really makes it up into Greenland on any runs this morning with little shift on the PV...does this mean we focus on later in Dec or hope for a quick change I wonder.

Edited December 1, 2014 by Ali1977

[Frosty.]

It looks like we are in for a rather disturbed early winter pattern with occasionally strong to gale force winds and rain but with colder incursions from the north west bringing sunshine and wintry showers, especially further north with a sugar coating of snow across some northern hills at times and some quieter frosty interludes, for example, there is very little in the way of mild weather on the Gfs 00z op run, it's dominated by near average to rather cold conditions with some days only reaching 3 or 4c 37-39f....winter is here at last...hooray  

Edited December 1, 2014 by Frosty.

[Snowman.]

So the middle of December after some positive trends now looks like being a damp squib. WAA never really makes it up into Greenland on any runs this morning with little shift on the PV...does this mean we focus on later in Dec or hope for a quick change I wonder.

Later December is the time frame were something of interest is may occur.

Not really loking for anything in the short term anything of a interest rests well out in fi were model bias could be the difference post day 10. For now we can just focus on getting some more amplification and that horrible lobe in Greenland/Canada move to the Russian sector. Patience is a vertue here along won expectation of disappointment. Don't work yourself in to thinking anything spectacular is going to appear this month.

On phone errors are likely.

Edited December 1, 2014 by SN0WM4N

[nick sussex]

Morning all

 

Not much change overnight with still some shorter term uncertainty with the UKMO most amplified between T96 and T120hrs and this brings down the coldest uppers.

 

The rest of the outputs bar the NAVGEM are flatter and hence less cold, so still a chance for some wintry showers into Scotland especially but its a narrow window of opportunity before the coldest air is pushed east.

 

In terms of the trends of the models, if given a choice I'd rather the ECM/GEM solutions as these continue to keep the Azores high displaced to the west.

 

The GFS P develops some very brief interest around the T240hrs mark but it gets there in a very complicated way and to be honest its a blink and you'll miss it affair.

 

There are no great options on show today for coldies, the pattern upstream is still looking flat, however just an outside bet here, I notice although we don't see any deep cold over  mainland Europe neither do we see any real push of milder air into that region,  from  the ECM and GEM, their suggestion is for lows to hit a brick wall as the Russian high edges west with trough disruption occuring near the UK, so if some interest is to develop I think its more likely to come from that route rather than any major retrogression of the Azores high, whilst the pattern over the USA and Canada remains flat this really is the only conceivable route to something a bit more wintry.

 

PS For those looking at the 850 temps for the UKMO on Meteociel ignore the T144hrs theres obviously an issue there as  theres no way given the synoptics that you'll get that milder air into Europe.

Edited December 1, 2014 by nick sussex

[MR EXTREMES]

The polar ridging is the other side of the NH. That means we are at the mercy of the northern arm if it's strong. A sinking upper trough isn't a bad start to winter with an overall weak p/v. yesterday I posted that I thought we would see amplification week 2 somewhere but if not, then the alternative was the sinking upper trough.

Lots more scatter on the ECM week 2 London T2 temps probably reflects fewer 'stagnant' HP dominated scenarios.

We are still a long way from a strong trop Pv so I don't see any reason for coldies to be concerned. few seasoned observers expected the first half of December to bring anything of strong cold interest.

Indeed after my outburst last week due to the continued excitement disappointment and reading in detail the strat thread then it's to be expected that we will need to pass through this faze.

Keep an eye out during this week for mjo to start a slow progression into a favoured evolution.

Mid December beyond has always been favoured if not the start of January.

Bit concerned of the talk of no wave action into the Arctic sounds a little worrying.

Solar activity has been increasing just recently perhaps this is adding fuel to the vortex and jet stream although this is just speculation of coarse.

The models are struggling beyond 96 hrs tho and any charts today could be eclipsed by better charts in the near future as it stands though nothing above really showing frost fog and some snow will feature in the forecast over the next 14 days.

Of coarse it's just the start of winter.

Considering last year I can't remember even a frost and people were displaced over Christmas because of the relentless vortex this year seems a lot calmer which I'd of thought is a good thing.

As I've said small changes can have big effects.

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY SUNDAY NOVEMBER 30TH 2014.

NEXT UPDATE TUESDAY DECEMBER 2ND 08:00

THE CURRENT GENERAL SITUATION  A cold front moves SE slowly across Northern and Western Britain with a ridge ahead and behind the trough affecting Central areas later tomorrow.

MODELS-2 WEEK HEADLINE A lot of dry weather especially at first before it slowly becomes more unsettled from the North later. Average temperatures with some frost and fog patches night and morning.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble forecast shows a brief dip South in the flow across NW Europe before returning North quite quickly and settling in a generally West to East flow across Central Britain from next weekend onward.

GFS OPERATIONAL The GFS operational this morning shows High pressure to the South of the UK in complete control of keeping wintry weather away from most of the UK over the next few weeks. Apart from a brief dip into a brief colder Northerly incursion at the end of the week the winds quickly back towards a milder Westerly quadrant and even SW later keeping things generally mild with some rain at times chiefly in the North and West

THE GFS PARALLEL RUN The GFS Parallel run is broadly similar with only the addition of another brief chillier period under Northerly winds in Week 2 before it too shows even milder weather under a South or SSSW flow late in the run under High pressure to the SE.

THE GFS CONTROL The GFS control run also offers little change from the High pressure based pattern with the centre alternating from a point to the SW of the UK or over France and Low pressure continuing to be steered East to the North of the UK with rain at times largely restricted to the North and West with a lot of dry weather elsewhere.

THE GEFS ENSEMBLES The GEFS Ensembles also show a fairly flat pattern with persistent High pressure to the South minataining generally benign Westerly winds across the UK with just the briefest intervention of colder conditions from the North later this week before a pattern reset takes place next week with more unsettled conditions perhaps edging further South down across the UK later in the period.

UKMO UKMO today shows a cold Northerly flow across the UK ahead of a toppling ridge SE through the weekend with milder Westerly winds reaching the NW and extending slowly SE to other areas late in the weekend.

THE FAX CHARTS The Fax Charts show a ridge of High pressure across the UK for the period with a NE flow over the South and a SW flow to the NW with dry and fine weather for many with areas of fog and frost in places. Later a cold front is shown to cross SE across the UK introducing a brief and chilly Northerly flow at the weekend

GEM GEM shows a pattern which deteriorates conditions across the UK from the North later next weekend and the start of next week. In the interim period dry and benign conditions ahead of a cold front introduces a brief but chilly Northerly at the weekend before milder Westerly winds by this time next week bring falling pressure and spells of rain followed by winry showers down across the UK next week in rather cold conditions in strong and blustery WNW winds.

NAVGEM NAVGEM too shows the brief Northerly at the end of the week with frost and fog patches night and morning. It later shows winds backing Westerly and becoming milder again with some rain at times then towards the North and NW.

ECM ECM this morning shows a pattern more alike to GEM as the brief Northerly at the coming weekend backs off towards the West with falling pressure next week and deep Low pressure sliding ESE across the Northern North sea sending cold fronts SE across the UK with rain and strong winds followed by colder showery conditions likely although from the 10 day chart it looks like milder weather behind a band of rain is knocking on the door of West and SW Britain again.

THE ECM ENSEMBLES The Ensembles show Low pressure close to the coast of Western Norway and High pressure near the Azores the most likely pattern we arrive at by Day 10 with a broad Westerly pattern across the UK delivering more unsettled weather than currently with rain at times and incursions of cooler and more showery weather in between with snow possible on Northern hills.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The theme remains for the UK to lie under the influence of High pressure most likely positioned just to the South of the UK over the period with a variety of long term solutions shown none of which point to sustained and notable cold weather.

MY THOUGHTS There still appears to be little evidence of any true Wintry weather for anywhere other than the highest peaks of mountains of Scotland and the North with High pressure as stubborn and persistent as ever across France and the areas towards the Azores throughout. While this stays here our only chance of true cold is from brief incursions of cold Northerly winds behind cold fronts of exiting depressions away from Northern Scotland before toppling ridges of High pressure bring back milder maritime air across the UK from the West. Nevertheless, this week will feel far from mild for many as the risk of frost and fog as the week to come is High under a ridge from the SW later. With time there is a slow trend towards the High slipping rather further South than currently allowing more depth to unsettled conditions feeding down from the North and perhaps allowing more enhanced incursions of colder air at times. Our problem lies with strong Jet flow aligned to the North of the UK rounding a large somtimes displaced Azores high and as I indicated in my reports late last week once this pattern forms it can become devastating for those looking for true Winter long lasting cold. There are normally two routes out of this pattern and that is a ridging of the High North through the Atlantic to greenland disrupting the Jet flow and allowing cold North winds to flood down over NW Europe and while this has been hinted at recently there seems little cross model support for this to happen anytime soon with pressure remaining stubbornly low near Greenland. Secondly we could do with High pressure to migrate from the South or SW across the UK to Scandinavia to once more disrupt the Jet South dragging depressions on much more Southerly latitudes as they approach the UK but that seems unlikely currently. Instead we have to look towards somewhat more unsettled conditions feeding down from the North as the High to the South or SW relaxes somewhat next week but rain and wind are then more likely than cold and snow though with colder air to the North it wouldn't take much to bring that South into the UK at times. In my opinion as of previous days I think the North is the direction to look for any cold over the coming weeks rather than anywhere else as an eventual ridging of High pressure North through the Atlantic will give us our best shot of any real wintry cold and some of the white stuff.

[carinthian]

Good Morning. Not bad winter charts this morning. Cold entrenched over Russia and Eastern Europe. Mild spell over Western Europe coming to an end. As we see it much of this week will have the Genoa Low in place with a fair bit of moisture in the Alpine Regions and increased snowfall over the weekend as the snow level drops. Still a trough likely to develop to the North and West of the Alps by Tues and Wed with some rather wet , cold and windy conditions over the Low Countries and SE Britain for a time. Most models post 144 hours show high pressure to sink south after a brief incursion of Arctic air into Britain and the North Sea and allow milder flow back into the North. However,there is talk of trough distruption coming up against the cold air further East and hence Lower heights than forecast may be maintained over much of mainland Europe. This would be the best route to cold for many and dare I say it snowfall. Plenty of time for this route to show in later numericals this week.

C

[bluearmy]

Take a look at the 500 spreads on Meteociel NAEFS through week 2.

Great illustration of how the Atlantic heights will vary through that period In their placement and intensity.

The consequences for us are clearly uncertain through that timeframe.

[blizzard81]

Well, looking at 5 to 10 day period and daytime temps not exceeding 5 or 6 degrees and mainly dry certainly beats 12 degrees with wind and rain. That sort of dross was obviously prevalent last year and to be honest most Decembers I can remember. So it is a very welcome change imo.

[Nick F]

Looking at the 00z GFS ens, certainly worth keeping an eye on trough disruption to the east of the UK over eastern Europe towards day 8-10, later stages of 00z ECM deter and the ENS mean showing this. It appears the polar low over NW Russia goes to allow the Siberian high back into play again, which will act more of a buffer to strong upper westerly energy coming in off the far north Atlantic/Iceland/Greenland, sending the energy SE over central Europe by day 8-10. 00z 8/10 day 500mb HGT comparison shows ECM better in this respect with the trough into central Europe and the Azores ridge further west:

 

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

On another note, Tropical Depression 22W SE of Guam likely to become a Typhoon towards Philippines over coming days and 00z GFS suggests a recurve N towards the Aleutian Low though not making much of it by the time it hits the E Siberian jet, long-way off this potential and probably not another Nuri, but merging with the upper troughing up there will perhaps strengthen ridging north towards the pole.

Edited December 1, 2014 by Nick F

[carinthian]

Looking at the 00z GFS ens, certainly worth keeping an eye on trough disruption to the east of the UK over eastern Europe towards day 8-10, later stages of 00z ECM deter and the ENS mean showing this. It appears the polar low over NW Russia goes to allow the Siberian high back into play again, which will act more of a buffer to strong upper westerly energy coming in off the far north Atlantic/Iceland/Greenland, sending the energy SE over central Europe by day 8-10. 00z 8/10 day 500mb HGT comparison shows ECM better in this respect with the trough into central Europe and the Azores ridge further west:

 

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

On another note, Tropical Depression 22W SE of Guam likely to become a Typhoon towards Phillipines over coming days and 00z GFS suggests a recurve N towards the Aleutian Low though not making much of it by the time it hits the E Siberian jet, long-way off this potential and probably not another Nuri, but merging with the upper troughing up there will perhaps strengthen ridging north towards the pole.

Nick,glad you have explained the reasons for possibilities of trough disruption to the east in the post 144 hr period. Certainly, something we have in our thoughts over here of the past few days.We still favour lower hieghts over Europe by days 8-10 than currently shown by several models.

C

[Paul]

Since winter begins today, now's probably a good time for a fresh thread, so going to lock this one in around an hour..