Model Output Discussion - 12th December Onward

[BLAST FROM THE PAST]

Interesting GFS run regarding fridays LP...My memory is hazy, but hasn't the GFS reverted back to its earlier runs from a few days back when it showed this system as a channel Low?...I'm sure I remember members posting on this....Interesting because there are tantalizing possibilities of a marginal snow event for central parts of the UK if this particular run verified?

Correct it showed that. It is my preferred thoughts re track too.

BFTP

[Optimus Prime]

Quite astonishing the ECM yesterday took the lead into downgrading the storm into nothing to be concerned about. Now the GFS has downgraded it and pushed it further south effecting Northern France.

Doesn't mean it won't happen but it bodes well for Friday to be windy and wet rather than stormy and wet.

Edited December 12, 2011 by Optimus Prime

[Osbourne One-Nil]

Much happier with the GFS track on fridays storm.

Could you say why? Trying to avoid one liners which don't actually add to the discussion.

[Cecil Hogmanay Melchett]

GFS low res again keen on transfering the azores high into Europe.

Only a trend at the moment but one we want to buzz off quickly.

edits i notice the continental advert on the tele promoting winter tyres has been on the air a lot less recently i bet sales are down on last year

Edited December 12, 2011 by happy days

[shedhead]

This may disappoint some gloaters in here, but a mild or very mild Christmas Day is far from "nailed", though it looks more likely than not to happen in the south. The reason for this is that although a build of pressure around the 20th December is set to happen following a brief northerly outbreak, the build of pressure could last for most of the last third of December as per Ian Brown's repeated projection (meaning a mild Christmas for all) or it could stick around for just a few days followed by a change back to colder and more stormy westerly-dominated weather around Christmas (hence possibly average to fairly cold, especially in the north).

The models have shifted into strong agreement on bringing Friday's low further south and making it less deep, though this still presents a chance of severe gales in southern parts of England and thus is still worth keeping an eye on. A marginal rain/sleet/snow event is probable on its northern flank, mostly snow above about 200m and rain near sea level but there is a possibility of localised snowfalls down to near sea level due to evaporative cooling.

@ajpoolshark- beat me to it, d'oh!

Meanwhile the northerly outbreak leading up to the hypothesised "mild Christmas" has been toned up in intensity, such that most places that see showers from it from the Midlands north will probably get snow. The main issue is the distribution of shower activity- a north to north-westerly flow leaves most of the UK in the "wishbone area" and Wales and SW England would be most favoured for showers, which would probably fall as a wintry mix there. It's a long way off though.

Yes this could happen, but can I ask what you see in either the current outputs or teleconnections to say this is a vaiable alternative to the increasingly well modelled mild/very mild SW'erly set up?

Edited December 12, 2011 by shedhead

[Cecil Hogmanay Melchett]

Some intensely low heights to the NW being shown on the 06z together with HP over Biscay, a real hairdryer is possible although it depends how close the High gets to the UK.

Synoptically going forward, if you are looking for cold down the line, then we are about as far behind the eight ball as it would be possible to be.

Blimey ian your posts are going into overdrive,lol.

No need to panic the very best winters of yesteryear only got going in Jan and sometimes Feb.

The extended outlook though does look a tad 'poor' shall we say.

[Paul_1978]

well it looking sort of mild for xmas day !!! but is there a beast from the east coming for the new year yes i know its f1 things could change!!!

How many times....it's FI.

[BLAST FROM THE PAST]

Some intensely low heights to the NW being shown on the 06z together with HP over Biscay, a real hairdryer is possible although it depends how close the High gets to the UK.

Synoptically going forward, if you are looking for cold down the line, then we are about as far behind the eight ball as it would be possible to be.

Ian

Can you state clearly what your thoughts are when this heatwave will start, how long it will last etc etc. FWIW I agree that a milder slot is coming but I'll also say its the start of the new pattern change and real cold will be upon us during 2nd week of Jan....and not a 5+ week run of mild SW'lies as you are thinking.

Just watching This Morning and The Express has the 100mph winds coming and worst storms for 30 years headlines..... Express has said it. :smilz38:

BFTP

Edited December 12, 2011 by BLAST FROM THE PAST

[snow drift]

Some intensely low heights to the NW being shown on the 06z together with HP over Biscay, a real hairdryer is possible although it depends how close the High gets to the UK.

Synoptically going forward, if you are looking for cold down the line, then we are about as far behind the eight ball as it would be possible to be.

I have a mental image of you sat at your computer, pressing post and chuckling to youself at the thought of how much this will wind people up!!!!

Thanks, another pile of posts questioning what you are saying and how it might not workout that way.

You maybe correct. Although we have been waiting a while for you to be so.

Now where is that ignore button?

[shedhead]

How many times....it's FI.

It might be FI Paul, but when was the last time we saw GFS produce a different evolution from T+180hrs? At least this time last week they were toying with greater amplification and some

cold shots in the pre Xmas week, but across the last 20 or so runs they have been very consistent and as I said previously, if they had been modelling bitter cold for Xmas in the same way

this forum would be in overdrive.

Edited December 12, 2011 by shedhead

[Osbourne One-Nil]

Can the point scoring and bickering stop now?

[Cecil Hogmanay Melchett]

We can all choose to ignore what we don't want to see, but from a synoptic development point of view I would be as confident as it is possiible to be about where we will be in 10 days time. And again historically, that position is a shocker to get out of - you can refer to many like that during the M/Era.

At face value i agree with much of that but things can and do change at very short notice.

A generally mild second half of Dec looks a good bet right now t hough for sure.

[Optimus Prime]

After last December and the previous two I think it was a safe bet for this one to come in more normal/mild with regards to pressure patterns as is often the case and in particular a very mild year like this.

Look at December 1981 and then 1982. CET was 0.3c and 4.4c respectively. North was cold in December 1982 and the far south was fairly average. December 1982 was extremely unsettled with some exceptionally unsettled weather. November 1993 was cold/November 1994 was the warmest on record. Patterns are matching quite nicely to those years.

I think Ian is perfectly correct in saying a mild or possibly very mild Christmas period is perhaps greater than evens chance this year. Early next week shows high pressure to the south after the cold northerly pulling in some mild air. Initially cold.

[Bobby]

Interesting GFS run regarding fridays LP...My memory is hazy, but hasn't the GFS reverted back to its earlier runs from a few days back when it showed this system as a channel Low?...I'm sure I remember members posting on this....Interesting because there are tantalizing possibilities of a marginal snow event for central parts of the UK if this particular run verified?

True, there are some cold uppers on the Northern edge of that low. If it aligns right it could be interesting.

The control shows this potential snow event

Worth keeping an eye on maybe...

[ChartViewer]

Synoptic pattern is still not showing anything by the way of a pattern change - GP and the Netweather forecast getting this right again for December by looks of it.

The jet is showing way too much energy with low heights to our North West. The best you could hope for at present is an azores high edging over UK for foggy and sometimes frosty mornings.

Think key thing is to keep an eye on GP and others postings on the In Depth for any signs of stratosphere changes which would help achieve either Greenland Heights or some sort of Scandi High which helps for an Easterley outbreak. Nothing this side of Xmas though i would suggest.

Mind you these storms look quite dramatic still even though Friday's seems to have edged further South into France somewhat. Would not like to be flying this week!!!!

Edited December 12, 2011 by Paul
Quoted post was removed

[WhiteFox]

What's all this "form horse" stuff anyway? Have I entered the Tote's forum by mistake??..

Indeed you are correct. One cliche is as bad as another... OK, milder zonality following on from the upcoming toppler seems the more likely outcome given the continuing strength of the jetstream and historical analysis. Ian Brown's assessment for the period following the toppler looks fairly likely, but I would not give an exact timescale for longevity.

Better?

[BLAST FROM THE PAST]

GFS06Z showing a pretty damn frigid 4 day cold spell starting on fris with temps barely above freezing in the day for quite afew places!!

Will look forward to a very festive run up to christmas with early and late frost for many

Yes indeed HD, 3rd week of month still set to be the coldest week and 'cold category' certainly favoured, also this Friday LP could bring some 'unexpected' snow for some favoured areas in the south.

BFTP

Edited December 12, 2011 by BLAST FROM THE PAST

[Thundery wintry showers]

Yes this could happen, but can I ask what you see in either the current outputs or teleconnections to say this is a vaiable alternative to the increasingly well modelled mild/very mild SW'erly set up?

Some recent model runs have shown this, and there are strong precedents for it (e.g. Decembers 1998 and 1999, both of which saw the jet temporarily reset to a northerly track and then head south again towards Christmas).

The latest set of runs are showing rather more support for the milder scenario than was the case over the previous few days, however.

If people were saying that there is strong support for a milder zonal outlook (rather like Nick F did above) I would agree, but some are saying that it's an absolute certainty to last through the Christmas period, and given the support for an alternative scenario, it isn't a certainty at all.

[shedhead]

Indeed you are correct. One cliche is as bad as another... OK, milder zonality following on from the upcoming toppler seems the more likely outcome given the continuing strength of the jetstream and historical analysis. Ian Brown's assessment for the period following the toppler looks fairly likely, but I would not give an exact timescale for longevity.

Better?

Yes, infinately so.. For what it's worth I tend to agree, we do not know the longevity of the mild/very mild spell, but again Ian (amongst others) was right in previously suggesting these setups are not easily broken once they become established. My thought for what they are worth is we're looking down the barrel of a fortnight at least and probably closer to 3 weeks, but by mid January I think we'll turn the current synoptics completely on their head and all this will be a distant (albeit still pretty bad) memory.

[No Balls Like Snow Balls]

I love the cold and snow, but I do see that more than likely we will be entering a period of milder SW/W winds from early next week.

Wouldn't like to guess how long it would last, hopefully only a couple of days from a personal point of view. I am afarid I do not see any continuation of cold zonality in any of the models from next week onwards :-(

[tinybill]

people keep talking about mild but this looks interesting for late dec

[weathe20]

so the mild SW winds get going at +204 on 6z. Nailed.

Edited December 12, 2011 by weathe20

[shedhead]

Some recent model runs have shown this, and there are strong precedents for it (e.g. Decembers 1998 and 1999, both of which saw the jet temporarily reset to a northerly track and then head south again towards Christmas).

The latest set of runs are showing rather more support for the milder scenario than was the case over the previous few days, however.

If people were saying that there is strong support for a milder zonal outlook (rather like Nick F did above) I would agree, but some are saying that it's an absolute certainty to last through the Christmas period, and given the support for an alternative scenario, it isn't a certainty at all.

Thanks for your response TWS. The highlighted line above is actually the most telling, at least this time last week GFS was modelling greater amplification at times, but recently run after run has been flatter and the upstream signals do not suggest things are likely to change anytime soon.

Edited December 12, 2011 by shedhead

[Iceberg]

Still so much uncertainty wrt to low on thur/sfri. More than I thought I have to admit. However the operation GFS has less support from it's ENS IMO and the models are struggling with the new potential track which might be just north of the M4.

The snow potential this coming Friday/Weekend is increasing as the low drifts further south allowing the colder air to undercut.

Finally we have the uncertainty of the rainfall, places could see 50-80mm depending on the low position this week.

All of the above have the potential for quite major distruption IMHO and the met office must be hoping that the models agree a bit more.

Longer term, the trend for HP over France are very strong in the ENS suite, this isn't a certainty but has to be the most likely scenario for this coming christmas period.

[Tim Bland]

06z Gfs op was a massive mild outlier! Lots of options on the table still! I expect a rolercoaster on here as some cold scenarios pop up over the coming runs!