Model Output Discussion - 19th - 25th December

[phil nw.]

Something strange going on anyway. Normally we see heights building into the north from the mid latitudes, that High over Svalbard just seems to build in situ.

It`s tempting to concentrate too much in the distant frames because of possible background influences.

I think there will be many twists and turns before the models get a real handle on the 500hPa pattern yet.

It is likely that the PV will come under some pressure eventually as the warming is forecasted to weaken the PV at the top levels within the next 8 days .

The models will likely build this in and are toying with different solutions over the polar regions.

Again though it should be emphasised there`s no guarantees things will evolve into a cold pattern for the UK.

I don`t wish to see this thread become too wrapped up in the Strato.warming forecasts let`s continue to discuss whats actually in the models and treat FI output as we always normally do--with caution.

Edited December 22, 2011 by phil n.warks.

[BurwellWeatherWatch]

and one thing that really struck me (apart from my propensity to moan quite a lot)

at least there is one constant then, in these uncertain times

[Paul]

Latest Xmas period weather forecast from Michael Fish - complete with his funky musical tie!

[chionomaniac]

ECM showing large differences with its previous run out to T+144. We have a ridge replaced with a deep depression. Could be interesting after this though.

[Cloud 10]

ECM showing large differences with its previous run out to T+144. We have a ridge replaced with a deep depression. Could be interesting after this though.

The models are having problems with this low,and if ECM verifies so will we!

[BLAST FROM THE PAST]

ECM showing large differences with its previous run out to T+144. We have a ridge replaced with a deep depression. Could be interesting after this though.

C, I was talking of this feature earlier to Karl a feature I mooched over last week but models showed it then ditched it, but thats UKMO, GFS, BOM and now ECM with that deep LP crossing UK. I think its something to watch. Also will we start to see a more NW flow following on as we see the HP to the south get pushed further south out of the way?

BFTP

Edited December 22, 2011 by BLAST FROM THE PAST

[phil nw.]

No real change in the model output this evening regarding the overall pattern.

A brief shot of colder air coming south tomorrow behind the rainband with an overnight frost leading into Xmas Eve.

The Azores High then extends into N.France by Xmas day and with deep low pressure to the north a brisk South Westerly flow moves across the UK.

http://www.meteociel.../fax/fax72s.gif

Into next week and we see the PJF wavering across the UK with a low pressure development moving towards Scotland

http://www.wetterzen...cs/Rukm1441.gif

http://www.wetterzen...s/Rtavn1441.png

http://www.wetterzen...cs/Recm1441.gif

It only looks a small feature- area wise- but as the ECM shows it could pack quite a punch--it is forecasted to develop along a steep thermal boundary and it is quite possble there will be some strong winds associated within it`s circulation.Unless it tracks further south than currently shown then any snow risk for the north looks to have disappeared for now.

There`s a lot of uncertainty from T144 on how the pressure rise is handled as the low moves East with the GFS much keener to build a decent ridge.

A view of the GEFs Thumbs show some variations on this at T168hrs.

http://www.wetterzen...n/fsenseur.html

Both models go back to a pretty flat zonal flow by day 8 with the jet maybe trending a little further south.

Edited December 22, 2011 by phil n.warks.

[damianslaw]

All models showing an interesting low pressure feature moving in during the 27th/28th - still a little too far away to say with certainty it will happen, but interesting all the same. It does look a small feature in extent though and is unlikely to herald another stormy period, the atlantic does look much weaker now than a couple of weeks ago.

Thereafter models don't seem keen on building strong ridge behind the low pressure - but there is a sign of the jet moving southwards again much as we saw during the first half of december, so the new year period could be a chilly affair with some cool northwesterlies. I do think the christmas-new year period will be a transitionary period - it often is, and a pattern change to something much more colder will begin to be shown in the models as we get to new year - courtesy of an ever increasingly weaker PV, but don't expect this development to be shown by the models in the coming daysjust yet..

The new year meto longrange 30 day forecast should be the first strong indication of the pattern change, it has been a stuck record in recent weeks waiting for those first signs of a change.

[Frosty.]

It's gone very quiet on here tonight but that's unsurprising as the models are completely lacking festive spirit, xmas day will be very mild and breezy with a lot of cloud and for scotland it looks like a washout with torrential rain and swly gales, into next week there could be a more settled interlude before it turns unsettled midweek and a risk of some wintry ppn in the north. Further on, the jet may begin to head further south as the european high drifts southeast so perhaps a reset to the cool zonal pattern we had through the first half of this month.

Edited December 22, 2011 by Polar_ Low

[Catacol]

I posted a comment on here earlier remarking on model similarity to a winter forecast, and it has gone without any marker. Do posts get deleted without notification?

[January Snowstorm]

The silence sums up the 18z perfectly lol

[Grimsby Snow Lover]

The silence sums up the 18z perfectly lol

I know!! At least day and night time temperatures should return to more normal conditions from Tuesday onwards. New years eve looks cool and settled which would be a bonus. Until the PV over Greenland weakens and stops fueling the jet we will struggle to see a pattern change.

[mountain shadow]

The silence sums up the 18z perfectly lol

Until the nice Arctic high right at the end.

[Frosty.]

The silence sums up the 18z perfectly lol

It will be 20 celsius warmer on xmas day than last year, probably one of the mildest christmas days for many years, boxing day also looking mild. All the mountain snow in scotland will melt although the models show a chance of mountain snow returning next week. If the european anticyclone pushes out of the picture, we should see an increasing chance of cold incursions into the new year but not until the high goes away. According to James Madden, a white christmas is increasingly possible, what planet is he from

Edited December 22, 2011 by Polar_ Low

[bluearmy]

Until the nice Arctic high right at the end.

Let's be honest - no evidence that much is changing on the output. There are tentative signs of heights slowly pulling west out of western Europe in a fortnight on naefs. That's a long way from a trough though. I believe that both gfs and ECM both take strat influences into account in their modelling. Things do look rather more amplified in gefs fi last few runs. However, there were amplified members over a week ago for next week and we now see that this means not much more than a transient block for the uk. Yes, some coolish uppers but no deep cold. Patience will, I hope deliver results for those of you waiting for cold. Seeing it where doesn't exist will just make the waiting that much harder for you.

[legritter]

evening gang ,iv been a lurking for a while .i think that new computer is on its way ,my son as hidden a box upstairs .i can realy get stuck into some modell watching once its up and running . looking at present charts i think there are many outcomes possible in the new year .and with plenty of TIME LEFT ,and the fact that proper winter can happen which 5 years ago most of us had given up on . im realy getting excited ,i know this is slightly of topic but seeing its quiet on here tonight can someone give me the best place to look for the most lowest DAM NUMBER RECORDED APROXIMATELY ACROSS THE ENGLISH CHANNEL ,AS IM TRYING TO GET A BLOG TOGETHER ,CHEERS AND LETS HOPE WE ALL GET OUR DREAM CHART .

[Timmytour]

. According to James Madden, a white christmas is increasingly possible, what planet is he from

He's either from another planet or he works for the Daily Express!!

I'm still pinning my hopes on a colder winter outlook from mid Jan. The pressure over Greenland is set to rise according to GFS....though by no mean dramatically. Got a feeling....well to be honest more a hope, that if this continues it will provide a platform for the colder weather I want!

[Frosty.]

He's either from another planet or he works for the Daily Express!! I'm still pinning my hopes on a colder winter outlook from mid Jan. The pressure over Greenland is set to rise according to GFS....though by no mean dramatically. Got a feeling....well to be honest more a hope, that if this continues it will provide a platform for the colder weather I want!

I also have a feeling that things will improve in january, no offence to mild fans but winter does look like arriving in january from what I have read recently but there is no magic switch we can flip, it will be a gradual descent, as you said from mid jan and according to GP it could be a very cold feb which would be a huge improvement on last winter, which ended just after christmas.

Edited December 22, 2011 by Polar_ Low

[snowblues]

looking at the n hemisphere charts,the polar vortex seems to be not bottled up and seems to be spreading around.i have noticed this on previous runs,is this because its in the low residue or can it be on to something?

thanks mike

Edited December 22, 2011 by 12-barbluesmikey

[stewfox]

Latest Xmas period weather forecast from Michael Fish - complete with his funky musical tie!

Interesting summary, why does he think father christmas comes from the west, would he not come from the east and not battle head winds ?

[skifreak]

All the mountain snow in scotland will melt

An ark would be required if that were to happen in 48hours. You have to go back to before 2006 for the last time there was no mountain snow in Scotland.

Some North West mountains or indeed perhaps the very far NW lower areas could still sneak in a technical White Christmas with falling snow on the day itself - going to be quite a close run thing from some of today's models / ensembles.

A few years back I was up North West and it rained all day, looked out between 10.30 and 11pm and it was turning to snow, before Christmas Day was out there was quite a covering with huge flakes piling down. It turned back to rain in the early hours of Boxing Day, by first light not a trace.

Edited December 23, 2011 by skifreak

[Robbie Garrett]

Nothing of interest in the short term looking at the runs, or maybe at least I'll get to fly in early January in some nice clear settled weather.

I guess the models do show some shifting around and change, and that in the longer term. 9th January Onwards we could get some decent weather.

[Brum Watcher]

GFS eye candy. changes on the horizon. F1 F1 F1, lol, the trend begins.....

[Duane S.]

GFS eye candy. changes on the horizon. F1 F1 F1, lol, the trend begins.....

That's the 18th of March. FI begins early Jan.

For me an increasingly interesting period is around the 6th Jan. Strong Jet that I wouldn't be surprised to see push further south. Potentially stormy and possibly the next big window for changes to start happening.

[Uncle_Barty]

GFS eye candy. changes on the horizon. F1 F1 F1, lol, the trend begins.....

It's FI