Model Output Discussion 26/10 2012 >

[Gibby]

Good morning. Here is the morning report on the 00z of GFS, UKMO and ECM for today Thursday November 1st 2012.

All models show the current Low pressure system anchored to the North of Scotland dominant to the UK weather for the period between now and next Tuesday. It's multi-centre core drifts around near Northern Britain for several days before sinking South then East over Southern Britain by Sunday/ Monday. Over Tuesday it exits East from Southern Britain leaving a brief, cold Northerly as a ridge of High pressure topples down over Britain through the day. The weather at the surface throughout this spell will contain showers or longer spells of rain with hail and thunder here and there, especially near Western coasts. Sunday looks favoured for some more prolonged rainfall in the South. Temperatures will be on the cold side of normal allowing some snow on Northern hills and mountains with a touch of frost at night occurring at night where skies clear for any length of time, most likely in the East. By Tuesday Western areas will become mostly dry as the ridge mentioned earlier topples in from the West.

GFS then moves forward towards FI with a rinse and repeat pattern with a couple of breezy but drier and slightly milder days before troughs spread back through in the WNW flow with further rainfall to be followed by a return to rather cold and unsettled NW winds with strong winds, rain, showers and hill snow all featuring once more over next weekend. For a short while through FI the cold will be strong enough to bring snow showers down to low levels in the North and East before less cold weather returns once more later in FI although by the end of the run a further rinse and repeat looks likely soon after the term of the run.

The GFS Ensembles show that Northern Britain sees 850's close to average at around 0C on the whole with rain at times throughout the run. A similar unsettled picture is generally indicated too for Southern locations with uppers near 0C too, though this is a little below the long term average down here for this stage in November.

The Jet Stream flow show a continuation of it blowing over Southern England and Northern France for the next 3-4 days. It does ridge north over the Atlantic early next week for a time but gradually the ridging collapses SE down over the UK later next week.

UKMO for midnight on Wednesday shows a ridge of High pressure collapsing SE over the UK with a rather cold and bright spell likely with most places seeing a dry day next Wednesday.

ECM shows a broadly similar pattern. As the ridge collapses away SE by next Thursday winds increase again with another surge of rather cold and unsettled weather developing from the North by next weekend with attendant rain, wind and wintry showers for all next weekend.

In Summary the models are in broad scale agreement this morning. As the current Low pressure finally loses it's grip early next week a window of dry and bright weather looks like developing towards the middle of next week before a return to the conditions we have now look like returning soon afterwards with a deep Low pressure over or near the UK with rain and showers in cold and windy conditions. Through this spell too snow is likely on Northern hills perhaps to more modestly sized hills as the Low pressure pulls East of Britain later next weekend.

[Glacier Point]

Kamchatkan ridge still in full control of the hemispheric pattern right now, more than facilitating our mid Atlantic ridge to remain despite the wobbles of NWP. No real prospect of rapid change, these changes expected to come off the back of a strengthening Siberian High / Pacific low which actually won't change things too much. We are progressing nicely through that logical progression following a rapid advancement of Eurasian snowcover.

GEFS day 11-15 mean depicts this nicely:

For those who look at the hemispheric view, this general trend in modelling hasn't changed. The models are struggling to deal with rising AO index value (tight negative height anomaly restricted to the Arctic Ocean with little cooperation outside of this), and this influences the placement of the mid Atlantic ridge, but it will not remove it.

Over the next few weeks, we should see a 10 day periodicity in the waxing and waning of blocking signal (placement further north of the mid Atlantic ridge) tied into mountain torque activity. The next MJO wave entering the western hemisphere will signal a step change in the blocking signal, full Greenland block or more signifivant amplification expected (late November).

Edited November 1, 2012 by Glacier Point

[Radiating Dendrite]

The charts seem to be getting a bit more "interesting" now

Both GFS and ECM point towards a colder regime being introduced from the North at around 240+.

The end of the GFS run was also encouraging, the PV looked to be disorganised once again after a temporary increase in organisation during the first part of this month.

As has been previously said, November is looking like being a cool month with milder air (+5hpa 850s) struggling to make inroads at all.

The word of this morning? Encouraging...........

[bluearmy]

Stewart - can you pop into the strat thread to answer a query please

[Biggin]

Kamchatkan ridge still in full control of the hemispheric pattern right now, more than facilitating our mid Atlantic ridge to remain despite the wobbles of NWP.

Kamchatkan ridge, seen this a few times GP, I presume it is Eastern Russia and west of Canada?? What Effect does it have on the weather and what is its significance to our weather, or is it more about its effect on the N pole ?? Sorry had to ask.

[Glacier Point]

Yes - and its such a strong anomaly (tied into Rossby Wave activity in the western Pacific interacting with the mid and high latitude meridional flows) that its effectively setting the downstream wavelength pattern of ridges and troughs.

Might be worth keeping an eye on CFS v2 week 4 forecast update today to see if picks the ridge developing around Greenland / Iceland end of the month which is the expected response in the atmosphere as we head into December.

[BLAST FROM THE PAST]

Interesting to see what this shift will do which GP mentions, although last 3rd I think we'll have a block in the wrong place for UK and 'very mild' being the theme. Lets see how this develops. The current thought being successive shots from the north over 1st half of the month pretty much as models see it and then the change.

BFTP

[tcc]

Yes we can't just assume that if GP's forecast is correct that the block will bring us cold!

It might end up being a west based -NAO which will be no good to us if your looking for cold.

[BLAST FROM THE PAST]

Yes we can't just assume that if GP's forecast is correct that the block will bring us cold!

It might end up being a west based -NAO which will be no good to us if your looking for cold.

Yes good call, chances are GP won't be far off BUT UK cold is never guaranteed

BFTP

[latitude]

Sorry off topic, but is there a model archive here?

[Ice BIast]

Sorry off topic, but is there a model archive here?

If you mean an archive for past model output, there are archives for the GFS, UKMO, and ECM on meteociel:

http://www.meteociel...ode=0&archive=1

http://www.meteociel...&archive=1&nh=0

http://www.meteociel...map=0&archive=1

Hope this helps

Edited November 1, 2012 by lce Blast

[Grimsby Snow Lover]

Sorry off topic, but is there a model archive here?

You can also access archieved charts from this German website

http://www.wetterzentrale.de/topkarten/fsreaeur.html

[johnholmes]

Just picking up on what the synoptic and anomaly charts continue to show and indeed the 500mb anomaly charts have been very consistent in showing NO active westerly set up through into at least the middle of November. They and the NAEFS ouput continue to show +ve areas of heights north of 50N and indeed further north than that with only rarely on the synoptic ouput any real westerly flow.

In terms of 'weather' that translates as mostly Polar Maritime air and briefly returning Polar Maritime air so mild is a word not likely to be seen in most forecasts for the next 2 maybe 3 weeks other than a VERY temporary feature ahead of any deepish surface low.

There is about a 30% probability in my view that a burst of Arctic air affecting the UK, just when is impossible to say, but within the time frame I am referring to that is into mid November which is as far as I ever attempt to predict (2-3 weeks ahead).

I do so wish some of the posters on this thread and others would CAREFULLY read and note exactly what is said by the more experienced posters for longer term connections and prospects, rather than post some of the fairly premature comments about what the poster THINKS they are saying.

By all means its great to see the involvement on Net Weather of many new folk but PLEASE do learn to walk before trying to run with meteorology. Its a fascinating subject, hugely complex, I've been trying to understand it it for over 50 years.

ps

In terms of further into November if I did suggest anything I suspect it would be along the lines being suggested over the last couple of days at least by UK Met. That is higher 500mb heights closer to the UK but far enough north for it to stay below normal temperatures with surface high pressure giving less precipitation and more in the way of overnight frost and possibly fog under any clear skies.

Edited November 1, 2012 by johnholmes

[Frosty.]

I would say the alignment of the jet profile from around the middle of next week onwards as it becomes tilted more nw/se gives us plenty of upstream chances of at least a couple of arctic outbreaks mixed in with the general polar maritime flow which looks like predominating throughout the extended outlook with a strong mid atlantic high or ridge and lows diving southeast towards the uk at regular intervals with a more amplified pattern. In the shorter to medium range, the latest ens mean from gfs and ecm shows a rather cold unsettled spell continuing and a chilly cyclonic weekend ahead and start to next week before an atlantic ridge pushes east towards middle of next week but it's not currently expected to last long, high pressure then becomes centred to the southwest of the BI and it would extend it's influence across at least the southern half of the uk with a less unsettled spell but still rather cool with wnw'ly winds being fresh to strong at times, the most unsettled weather probably becoming restricted to more northern parts of britain but then the very unsettled and rather cold pattern returning to all areas further on, the Ecm 00z ens mean shows an arctic outbreak towards T+240 hours with reload potential. I think the chances of any mild weather is slim and if there is any mild weather it will only be very temporary with most of the time being cold zonal with showers turning wintry at times, especially on hills and fairly frequent overnight frosts, temps in the range of 5-8c by day, a little milder than that at times, but 2-5c max in any arctic outbreaks, windchill also playing a major part in making 7c feel closer to freezing in the very windy spells.

[Snowman.]

All fun and games from the CFS this far out so nothing should be taken from it but look at that low as it heads into Ireland.

Powerful stuff!

[Liam J]

All fun and games from the CFS this far out so nothing should be taken from it but look at that low as it heads into Ireland.

Powerful stuff!

http://modeles.meteo...s-0-1074.png?00

It's safe to say that beast would cause major problems, if anything of that intensity actually came off of course!

The CFS has been going for a pretty stormy December on quite a number of runs of late, a long way off but this is also what Roger has been hinting at with his seasonal forecast.

[snowmadchrisuk]

All fun and games from the CFS this far out so nothing should be taken from it but look at that low as it heads into Ireland.

Powerful stuff!

http://modeles.meteo...s-0-1074.png?00

Some of the other Models have that low running down the North Sea instead , but 15 days out so who knows. CFS seems worse at predicting short term than long term but maybe thats how its designed. Looking at a few of the Models it could get rather Frosty in the South by the middle of next week with NW flow but High pressure Nudging across from the SW. I'm right on the coast so Frost is rare but inland Southern England could record there first negative temps of the Season .

Edited November 1, 2012 by snowmadchrisuk

[BLAST FROM THE PAST]

Just to highlight and try and clarify what I am suggesting may happen for last 10 to 12 days of November where I think we could see a very mild set up occur and that its not really too far removed from GPs outlook inasmuch we see a big GHP. The following chart is 06z and T384 GFS so is just being used to show a big Greenie block but in wrong place and that could bring very mild conditions to UK.

West based -ve NAO, ATlantic blocked BUT HP over France starting to pump up warm air towards us. Pattern is very amplified, non zonal but UK is not cold. I think this is a type of scenario I see happening using my method as its not just mild but very mild period I see, but I do agree with more northerly bursts over next 2 weeks or so. So lets see how the month develops...

BFTP

Edited November 1, 2012 by BLAST FROM THE PAST

[johnholmes]

another nicely presented summary frosty-very easy for newer folk to understand as well, showing different models and what they are predicting.

[Frosty.]

another nicely presented summary frosty-very easy for newer folk to understand as well, showing different models and what they are predicting.

Thanks John

[AWD]

You might not have thought it by looking outside (well not IMBY anyway) but pressure is looking to drop to quite low values across the UK in the next 24 hours. Sub 970mb quite widely;

http://www.wetterzentrale.de/pics/brack0.gif

http://www.weatheronline.co.uk/cgi-bin/cgicurrentgraph?CEL=C&ART=kartealle&LANG=en&JJ=2012&MM=11&TT=01&TIME=0700&TYP=druck&KEY=UK&LAND=UK&CONT=ukuk&TIME=1351754195

Its actually been one of the best/sunniest days of the last 10 days or so IMBY though, which goes to show that quite often, especially at this time of year, LP can mean sunnier days than HP controlled weather.

[legritter]

I said the other day that the weather could perhaps towards the end of next week ,come under new Management .But with latest chart and data info more apropriate words at this stage would be Same management but perhaps new crew .a cold zonal i think continuing after a brief RIDGE next week but with low pressure systems tending to move further south .And a fair possibility of the 528 Dam line pushing regularly south .bearing in mind that we will be another week on from now and if you remember we had a good arctic incursion early last weekend ,move that event two weeks on and to me it all looks very interesting with potential .I am by no means forecasting the next big one but certainly beats that swear word for some [MR Azores High ] .we work together good as a team of weather enthusiasts and lately there as been some v good posts . im as guilty as Hell at cherry picking but when that juicy chart pops up on chart viewer i get carried away and start imagining all sorts of juicy synoptics .But it is important as another poster said lately , we must all learn to walk first and read the posts from more educated and experienced posters and take all information on board .dont forget any new members and visitors ,pop into the learning area ,read up and get off the cimputer and look skywards .you can learn loads by looking at upper air charts ,and then looking at cloud formations contrails etc ,theres a whole lot of info on Contrails on google [sCIENCE OF CONTRAILS ] .well we have tonights ECM and Met office and another run of GFS so plenty of scope for this evenings Forum ,Regards

[carinthian]

A lot of moisture in the the Alps at the moment. Good for increased snowfall at altitude. Talk in the tourist office is the possiblity of the lifts opening early for the start of the season based on its long range forecast provided. The latest prognosis is for the zonal jet to be strongest south of 50 N until mid- month with plenty of moisture, this being quite unusal in mainland Europe at this time of the year. The second half of the month indicates a more meridinal flow with the high pressure centred to NW of the British Ises and the upper trough aligning NE/SW further to the east. Not exactly a omega scenario yet for a prounounced cold set up, but encouraging prospects for the start of the ski-ing season with limited milder conditions forecast for much of Europe.

C.

[Frosty.]

Just to highlight and try and clarify what I am suggesting may happen for last 10 to 12 days of November where I think we could see a very mild set up occur and that its not really too far removed from GPs outlook inasmuch we see a big GHP. The following chart is 06z and T384 GFS so is just being used to show a big Greenie block but in wrong place and that could bring very mild conditions to UK.

West based -ve NAO, ATlantic blocked BUT HP over France starting to pump up warm air towards us. Pattern is very amplified, non zonal but UK is not cold. I think this is a type of scenario I see happening using my method as its not just mild but very mild period I see, but I do agree with more northerly bursts over next 2 weeks or so. So lets see how the month develops...

BFTP

How long do you think the very mild weather would last Fred, if indeed we do have to endure a very mild phase, are you thinking we would then see a change back to colder by early dec or continued mild?

Edited November 1, 2012 by Frosty039

[latitude]

Just to highlight and try and clarify what I am suggesting may happen for last 10 to 12 days of November where I think we could see a very mild set up occur and that its not really too far removed from GPs outlook inasmuch we see a big GHP. The following chart is 06z and T384 GFS so is just being used to show a big Greenie block but in wrong place and that could bring very mild conditions to UK.

West based -ve NAO, ATlantic blocked BUT HP over France starting to pump up warm air towards us. Pattern is very amplified, non zonal but UK is not cold. I think this is a type of scenario I see happening using my method as its not just mild but very mild period I see, but I do agree with more northerly bursts over next 2 weeks or so. So lets see how the month develops...

BFTP

Forgive me if im wrong, but isnt that a surface high on that chart you posted, not the Greenie High that usually causes cold to feed into the UK. If it is a surface high, it wouldnt be in the wrong place because it wouldnt make any difference to achieving a cold shot or not.