Model Output Discussion - 28th November

[EML Network]

I think over the next few weeks there's likely to be a lot of "IMBYardism".

I fail to see a country wide snow fest, seems to me that the same old places are likely to have the fun and games, namely the midlands, North East and Scotland doing particularly well.

Hats off to the Met Office 5-15 day outlook , for once we seem to have the models all going along the same lines, I doubt that Mid N.Atlantic Low will undercut, I suspect it will stall as per GFS and allow a ridge of High Pressure to sit over the UK, any easterly would likely be short lived from that and not have much Precipitation embedded within.

Overall one can't complain...unless you are like me and you live on the South Coast... we'll not get anything from this, unless we can get that Low to undercut and run through France

Edited November 30, 2012 by EML Network

[Karl83]

First the cold then the snow. I see posts questioning snow potential but already this is better than last year without a doubt. Our chances are better if u ask me and to be fair you all know anything can happen at any given time.

[nick sussex]

Regardless of what happens after 144hrs in the nearer term at least the models agree on that low tracking se'wards.

There is the chance of some snow on the backedge of the low and after this some snow showers into eastern and ne areas depending on the flow into the UK.

The shortwave modelled after this though is likely be difficult to pin down in terms of track, this could deliver more snow on its eastern flank.

There is though that uncertainty with the low to the sw and how this interacts with any shortwave moving se through the UK.

Edited November 30, 2012 by nick sussex

[Frosty.]

I fail to see a country wide snow fest, seems to me that the same old places are likely to have the fun and games, namely the midlands, North East and Scotland doing particularly well.

Yes it's looking winty again after the milder blip on monday, models coming into line with each other for some cold shots over the next few weeks and some surprise snowfalls for some, the current frosty spell is a real tonic after all the recent torrential rain.

Sadly on monday, temps are back into double figures but it's brief. Another worry is more flooding as heavy rain into the west on sunday morning, pushes east through the day and lasts through most of monday, so more flooding seems inevitable.

I'm really pleased that the promising background signals are beginning to work there way into the operational output, model watching is going to be increasingly thrilling as this develops in the days ahead.

Edited November 30, 2012 by Frosty039

[Catacol]

I see no widespread snow for anything longer than a day or so

You may well be right, but this is where we need our realism. At this time of the year a snow event that lasts a day or so is a good result. A "widespread" snow event for a day in early December is an even better result.

And the point is that the current synoptics for next week might well suggest this, but then ensemble means are pointing to longer term temperature decrease.

Let's see the glass as half full rather than half empty... and if someone walks past and knocks it onto the floor completely just wait for the refill because the "vortex" barman is in Happy Hour mode.

[Catacol]

As long as the portion of vortex is present there it is going to be very difficult to get an easterly in place

Disagree with this bit anyway. Mean forecasts are transferring the majority of the energy away from the Canadian side, and the signal for a mid atlantic ridge grows stonger. Where the block moves to is the question... but the block is strengthening. I think the low pressure that is coming through early next week will be the only victory for the canadian vortex: from midweek onwards the block will win, but not before we get chances of boundary snow. And beyond that I mentioned Feb 91 a few pages back: there is potential for a scenario like that again... and when I say potential I dont mean FI wishful thinking but potential based on ensemble means, teleconnections and a decent number of operational runs. That's not a guarantee; it just raises the % chances.

Edited November 30, 2012 by Catacol_Highlander

[Methuselah]

Hats off to all those who said that our first taste of cold would come from the north or north-west, and that any major surge from the east or north-east would come later!

Well done, guys!

[NorthNorfolkWeather]

Disagree with this bit anyway. Mean forecasts are transferring the majority of the energy away from the Canadian side, and the signal for a mid atlantic ridge grows stonger. Where the block moves to is the question... but the block is strengthening. I think the low pressure that is coming through early next week will be the only victory for the canadian vortex: from midweek onwards the block will win, but not before we get chances of boundary snow. And beyond that I mentioned Feb 91 a few pages back: there is potential for a scenario like that again... and when I say potential I dont mean FI wishful thinking but potential based on ensemble means, teleconnections and a decent number of operational runs. That's not a guarantee; it just raises the % chances.

A considered and sensible post, everything at this point is about % chances of things happening.

As for this picture, that's quite a block to the East of us if it comes off

[Iceaxecrampon]

I think over the next few weeks there's likely to be a lot of "IMBYardism".

I fail to see a country wide snow fest, seems to me that the same old places are likely to have the fun and games, namely the midlands, North East and Scotland doing particularly well.

Hats off to the Met Office 5-15 day outlook , for once we seem to have the models all going along the same lines, I doubt that Mid N.Atlantic Low will undercut, I suspect it will stall as per GFS and allow a ridge of High Pressure to sit over the UK, any easterly would likely be short lived from that and not have much Precipitation embedded within.

Overall one can't complain...unless you are like me and you live on the South Coast well not get anything from this, unless we can get that Low to undercut and run through France

........just think of all that sun you get EML

Yes the models last week had ppn snow progged for today which turned this MB into a frenzy - OK not the promised snowmaggedon but METO has a ppn band moving down tonight mainly topping off at 2k ASL - models look promising for next week maybe a dry easterly after initial rain but at least there is a festive feel to it.

Ian IAC

[Catacol]

A considered and sensible post, everything at this point is about % chances of things happening.

As for this picture, that's quite a block to the East of us if it comes off

True - but we dont want it positioned quite like that! Still... one step at a time.

[johnholmes]

this link may interest some of you wanting a version of what may happen 1 to 2 weeks or so down the line?

http://forum.netweather.tv/topic/75105-model-thoughts-summaries-27th-nov-onward/page__gopid__2422299#entry2422299

[Robbie Garrett]

To be fair the models predicted a cold end to November 2 weeks ago. Right now it's freezing outside in Central London. ...

[Frosty.]

It's so good to see an arctic plunge within the reliable timeframe instead of deep in FI, it now means we can be more confident of a cold plunge pushing south towards midweek with snow showers and widespread frosts, the 6z looks to have shunted the trough too far east but I believe it will end up being modelled further west to make the cold snap last longer and bring more snow showers, it's still a classic set up as it is because although it briefly becomes less cold with rPm air across the uk by the end of next week, it's only a prelude to that massive cold anticyclonic block pushing bitterly cold air westwards towards the uk, this gfs sets up a brief mexican stand off as a large atlantic depression engages hostilities with the frigid cold block and then typically the gfs goes into default mode and allows milder weather to push in but there are signs we will have cold blocking covering the uk for most of december with only brief milder interluds, there could be a lot of snow through december.

The extended 16-30 day meto update is looking cold with frost, freezing fog and more chance of snow being the main precipitation although a drier than average spell is mentioned so the snow will probably be more in the form of snow showers around the coasts apart from trough activity.

Edited November 30, 2012 by Frosty039

[Paul]

I know I'm like a stuck record but can we discuss the models in here please, there are threads to discuss the cold, threads for the metoffice alerts and every other subject under the sun, so can we keep this thread to what it's meant for and for what members turn up to read about, thanks.

[Jonan92]

Interesting chart from GEM

[Catacol]

this link may interest some of you wanting a version of what may happen 1 to 2 weeks or so down the line?

http://forum.netweat...99#entry2422299

Yes - good verification based on the sensible ensemble mean trend. Will look forward to your next output today... ensembles suggesting the height anomaly will transfer in the medium term a bit further east thereby sharpening the potential for a longer easterly feed via the low heights to our south. Cold overall with wintry potential.

On another tack did you catch my reply to your MetO definition of cold a few pages back? Very few months come in at 4 degrees below average - only 9 Decembers in total on the entire CET record do that, so is the MetO definition of a cold month really that severe?

[nick sussex]

The main point of uncertainty after the low pressure has cleared se is the possibility of a shortwave heading se from near Iceland:

That small feature shown to the nw, the models handle this differently in terms of placement, the UKMO has this much further west, this mornings GFS 06hrs run developed this more and took it further east.

The complications are not just its track but whether the low to the sw engages this which makes any forecast even more difficult.

If this verifies then areas on the eastern flank of this shortwave are likely to see some snow , the ECM actually also gives a chance for some backedge snow as this clears aswell.

Much of the wintry potential is dependent on where the models decide to cut energy se'wards,and this makes any forecast difficult.

[chris55]

The ECM00z runs keeps 850s between -2 to -8 throughout the run once the milder blip is through on Monday, and with what looks like quite an unstable flow snow could be a factor for many next week especially on slightly higher ground and further north but not exclusively so. As others have mentioned the shortwave at 144 hold the most potential,

Also ends with a nice block to the east, overall a good wintry ECM 00z.

[Frosty.]

I forgot to show next weeks cold snap/spell..so here is what the gfs 6z thinks, as I said, this could upgrade into something even better, tons of potential for a longer cold spell within the extended ensembles and the current background signals in general.

Edited November 30, 2012 by Frosty039

[Catacol]

GFS 06z has the mid atlantic high even more dominant before it is sucked to Scandy. You can see here the "tropical" low pumping heights up to its north in this shot at 150h - personally it looks wrong to me and is not quite the evolution we want at all really unless heavy frost and dry is what you are after... I'm with SM on this one though: years of lurking and model browsing has tended to encourage me to ignore the 06z. It seems frequently to get itself into knots.

I'm still hopeful of the Scandy high spawning more from the east and therefore winning the race with the mid atlantic - that way we get more chance of wintry showers, frontal attacks from the SW and the holy 1991 grail of fronts pushing up from the south if the pressure there is low enough.

It is fascinating stuff at the moment. Ensemble means once again showing the way to go overall.

Edited November 30, 2012 by Catacol_Highlander

[phil nw.]

A heads up- we will lock this in a few minutes ready for the evenings entertainment supplied by the 12s.

[Timmytour]

^{Looking through the latest} GFS ^{run, there are some amazing looking charts, of the type I suspect are rarely seen.}

^{While there's a lot to be encouraged about, I really don't see the signs of prolonged cold spells, but rather intermittent bursts.....still a vast improvement on some years ago.}

^{I can't help thinking that the models now are bearing out what some were saying a month ago. Both those who were saying that everything looks set for a classic winter, and those who were exercising caution because the UK might just be in the wrong position to benefit from all the positive stuff going on in the background.}

^{Just a shift of a few hundred yards east or west makes a hell of a lot of difference to us. To me its no wonder the models fluctuate so much, especially when I imagine the kind of set up we have now is one for which precious little experience would have been factored into the programming}

Edited November 30, 2012 by Timmytour

[phil nw.]

Locking this now.

New thread here