Model Output Discussion - 30th November onwards

[sunnijim]

Not sure anyone has spoken seriously about FI mild to be honest. Yes an SE feed would be cold, especially in the SE, but the models I've looked at this morning are not suggesting that at 144hrs for the vast majority of the UK

 

 

GFS

 

 

UKMO

Beyond this timeframe the flow may start to back a bit, but then again it's equally likely to veer a bit. So looking 48-144hrs the

big 3 suggest any surface cold will occupy a similar size area to any significant warmth...i.e c.10-20% of the country.

 

Most of us will be on the mild side rather than the cold side.

I would just query your percentages,in the height of summer i would agree on 'significant warmth' but at this time of year i can only see western extremities slightly above average from the charts you produce,most around average or a tad below and SE cold or possibly very cold under any persistant gloom/fog.

[Summer Sun]

NAO from yesterday showing a very clear trend, a negative one 2 successive update its going negative I wonder what today's update will show

 

 

The ensembles are very clear this morning from Sunday or Monday for around 10 days we have 850's above average across the UK

 

[shedhead]

I would just query your percentages,in the height of summer i would agree on 'significant warmth' but at this time of year i can only see western extremities slightly above average from the charts you produce,most around average or a tad below and SE cold or possibly very cold under any persistant gloom/fog.

That is called model interpretation sunnijim, it's inherently subjective, so you might well be right.  Let's see come early next.

 

Edit: The 06 GFS looks pretty mild for next Monday, even in the SE....IF it's correct of course.

 

Edited December 4, 2013 by shedhead

[Matty M]

A almost complete downgrade of that northerly is compounded on this mornings output.

 

One to remember for the future, with the models particularly ECMWF over amplifying the flow.

 

If we were to analyse recent output, the much criticised GFS was closest to getting this synoptic correct.

[shedhead]

A almost complete downgrade of that northerly is compounded on this mornings output.

 

One to remember for the future, with the models particularly ECMWF over amplifying the flow.

 

If we were to analyse recent output, the much criticised GFS was closest to getting this synoptic correct.

Indeed, not for the first time GFS picked up the weakening trend, but to be fair UKMO started downgrading the N'erly quite significantly yesterday too....gone from 'blink and you'll miss it' to just 'miss it' now for the vast majority.

Edited December 4, 2013 by Paul

[Tim Bland]

Look how warm Scandinavia gets next week !

 

Edited December 4, 2013 by Paul
Point scoring removed...

[Rocheydub]

A almost complete downgrade of that northerly is compounded on this mornings output.

 

One to remember for the future, with the models particularly ECMWF over amplifying the flow.

 

If we were to analyse recent output, the much criticised GFS was closest to getting this synoptic correct.

Whilst I do agree with you Matty, the GFS did also show us all under a stonking northerly flow for a few days a while back… All the main NWP models were sucked into this in one way or another. But as I said, I agree the GFS was much more maligned than others and not with any warrant.

[Severe Siberian icy blast]

A almost complete downgrade of that northerly is compounded on this mornings output. One to remember for the future, with the models particularly ECMWF over amplifying the flow. If we were to analyse recent output, the much criticised GFS was closest to getting this synoptic correct.

completely agree. The gfs was going for a much flatter pattern than the other big 2 . Everybody slated it but when push to shove the gfs is good at picking upon trends. Yet it has its flaws . But initially its good ,then it tends to drop it , only to pick it back up, this wkends northerly is no different to last wkends short one. The difference between them is one was modeled correctly . The other one was misunderstood big time by the models. The vortex strength is too strong to allow ridging northwards . And until we can get a clear move away from a particular area be it greenland or siberia without leaving segments behind then high lat blocking is just not going to occur. A scandi high is a possibility if 1:the vortex moves to Canada without leaving energy behind and 2: the jet is split but a stronger southern arm. If the northern arm is strong then in my opinion a sustained block is unlikely IMO

[radiohead]

People should remember this episode when certian members keep banging on about "GFS being rubisih" and "ECM has the pattern correct" etc. I even remember one respected member posting regularly about how this weekend would be almost 'record breakingly' cold and to ignore the GFS.

 

I still find the best thing to do is not to ignore any of the major models (GFS, ECM, UKMO), no matter what their output is showing. It's always very tempting to latch onto the model showing the best possible outcome, but you just have to leave personal bias out of model interpretation, otherwise you can't look at them equally. Yes, the ECM is usally the best in the long term, but like a very good football team, it's not going to win every single match, and at times all the major models are as good (or bad) as each other.

[Severe Siberian icy blast]

As it happens the 06z is not a million miles away from delivering an easterly . Its a sse but there does look to be more ridging into scandi on this one. Sorry can't post charts . Lets just get this pathetic of a northerly out the way first. Then look to what's coming next week. Remember next wk is a long way off and absolutely everything can change by the time sat comes .

[Duane S.]

according to the deep fi gfs strat forecasts, something is brewing high in the strat. Even if it verified, it might stay there so just of note at the moment. The gefs certainly becoming less interested in the scandi ridge persisting through week 2.

 

Yep been watching that, albeit relatively minor, warming forecast myself over the last few days. It will be interesting to see if it can intensify and creep down towards 30mb. Certainly may help shake things up a bit later on in the month!

[Snowman.]

Are main problem is east as heights from the russian block have not been able to make it west.

 

6z 2 days ago.

 

6z today 

Edited December 4, 2013 by SN0WM4N

[TSNWK]

UKMO caution (as have some on here) that with light gradients & little mixing, the higher Theta-W regime in SE/S shouldn't be taken as signal for 'mild': boundary layer still chilled and temps typically to average at best. Based on 12z suites yesterday, lower prob now of deeper cold from E into 15d trend period but beyond that remains an imponderable. Dry signal remains striking in all but MOGREPS-15 ensembles (latter a bit noisier for heavier PPN later in period). 00Z analysis due later this morning.

 

Thank you for these little snippets Fergie. Any news from 00Z analysis please.

[shedhead]

Well IF the 06 GFS verifed we would be looking at a very dry, if not exceptionally dry first 2/3rds of Dec, with little sign on the T+384hr of wet weather returning immediately thereafter either.  This does look to be the overridding signal for now, but without question temps would be on the mild side of average too for most parts of the country.

[TEITS]

I feel I need to add some balance because the word "Mild" is being incorrectly used for the outlook period.

 

The 06Z is a good illustration of what i've been harping on about. If we look at the charts below you would assume mild.

 

http://www.wetterzentrale.de/pics/Rtavn2041.png

http://www.wetterzentrale.de/pics/Rtavn2042.png

 

However due to HP, flow off continent the majority of us would actually see chilly max temps during the day and frost at night.

 

http://www.wetterzentrale.de/pics/Rtavn22817.png

 

Just remember mid Dec is when you can experience the coldest temps under such synoptic set ups and one of the main causes is the lack of daylight hrs. I have known ice days, well below freezing mins and hoar frost remaining all day under these conditions.

 

Should mention all of the above does not apply to extreme W/SW!

Edited December 4, 2013 by TEITS

[shedhead]

I feel I need to add some balance because the word "Mild" is being incorrectly used for the outlook period.

 

The 06Z is a good illustration of what i've been harping on about. If we look at the charts below you would assume mild.

 

http://www.wetterzentrale.de/pics/Rtavn2041.png

http://www.wetterzentrale.de/pics/Rtavn2042.png

 

However due to HP, flow off continent the majority of us would actually see chilly max temps during the day and frost at night.

 

http://www.wetterzentrale.de/pics/Rtavn22817.png

 

Just remember mid Dec is when you can experience the coldest temps under such synoptic set ups and one of the main causes is the lack of daylight hrs. I have known ice days, well below freezing mins and hoar frost remaining all day under these conditions.

 

Should all of the above does not apply to extreme W/SW!

The points you make are quite correct when looking at charts in FI such as the T+204hr ones you've posted, but not in what most would consider the 'outlook'.  Moreover, I'm not sure anyone has talked about it being mild everywhere at that range.  The mild, milder, mildest...call it want you will synoptics look like being early next week based on the latest output, i.e in outlook not FI territory. Where we go thereafter is still open to question.

Edited December 4, 2013 by shedhead

[bluearmy]

although the broad outlook remains with heights rising to our east and remaining high over the nw europe, the 00z extended are more enthusiastic re a stronger flow over the top of the block. that will prevent it getting far enough north to allow any deep cold incursions across the uk (there is a spread remaining on ncep for mid month easterly but this looks doubtful to me).infact, the background noise would seem more attuned to the atlantic making significant inroads over time and forcing the block se somewhat.

[Frosty.]

You have to laugh, the Gfs 06z op run shows an early taste of winter across the north, especially scotland during the next few days, by the start of next week we have an early taste of spring with sunny spells and temps of 12-13 celsius.

[legritter]

Yes  FROSTY ,spring is coming very early this season ,Next week ,followed by Winter ,get all the shopping done now plenty of STellas in the garden you wont need a fridge ,KEEP THE FAITH UP GANG ,ups and downs in our hobby so tomorrow could be rosy .

[Catacol]

Quick update at work - change in the lower strat signals this morning. Support for scandy ridge has fallen away with a much less pronounced ridge shape

 

 

 

but wave 2 warming still forecast and signs possibly of enhancing at day 10

 

 

10 days charts show the predicted easing of the vortex away from the Canadian side underway, but not in a particularly dramatic or disrupted fashion.

 

So unfortunately my hopeful post of yesterday is now less hopeful. Heights will build towards Scandy but probably not get far enough north for any cold and instead we may be on the western edge of the ridge and enjoying some unseasonal warmth. On the output this morning any interest for cold is looking as though it will be after Xmas after all - the call of many on here in mid november.

 

RJS will be smiling this morning.

[Ian Brown]

although the broad outlook remains with heights rising to our east and remaining high over the nw europe, the 00z extended are more enthusiastic re a stronger flow over the top of the block. that will prevent it getting far enough north to allow any deep cold incursions across the uk (there is a spread remaining on ncep for mid month easterly but this looks doubtful to me). infact, the background noise would seem more attuned to the atlantic making significant inroads over time and forcing the block se somewhat.

Yes with the deep PV I would expect the latter solution is where we headed. 

[snowmadchrisuk]

I think the High will start off with temps around 12/13 deg next week due to the very long fetch of air from far South , but I think it will be one of them High's that will get Colder as time goes on , Fog in The midlands I imagine will start to become widespread by the end of next week , followed by Frost at night causing Freezing fog and low maxes and even lower mins... 

[Frosty.]

Yes but it hasn't happened yet and the weather could have other ideas so the smiling can be put on ice for now. :-)

Edited December 4, 2013 by Frosty.

[phil nw.]

Back to the here and now and the latest NMM 06z run shows the Arctic incursion seems now confined to the far north.

Around Friday 00z appears to be the furthest south the deep cold get's with snowfall now mainly north of the Great Glenn and the Grampians.

 

 

The deep low tracking much more on an easterly path than expected some days ago quickly taking the cold away with it.Still very windy for a short while but maybe some downgrade to the earlier severe gusts forecasted earlier.

 

The worst going down the N.Sea but would still need watching around eastern coastal districts i would imagine-re.any tidal surges but i am not sure on this-maybe others who study that could comment.

 

Notice though the unusual depth of cold coming in to N.Scotland -13C uppers touching the far north briefly.

 

What might have been if the pattern had retained the amplification modeled some days ago.

 

[Yozzer]

 

RJS will be smiling this morning.

Can anyone give me a link to RJS' winter forecast please? Ta muchly.