Model Output Discussion October 2012

[shedhead]

Another sound, rational post from Gibby to counter those who seem hell bent on breaking the rampometer a full 6 weeks before official Winter even starts! Certaintly the prospect of some colder conditions to close out the month, but not before a spell of mild, even very mild and hopefully much drier weather for many.

[SMU]

Morning can someone please save & attach the GFS 204 europe 500 MB chart so I can run some commentary on it-

Remember the 06z is up next- what will the detail look like around our forecast timeframe...

the 00Z ECm has moved a long way to the GFS this morning but still cluttered with shortwaves - not allowing any firm pattern to develop-

Money still on the GFS...-

S

PS to shedhead- I would just bat it back- noones ramping, just enjoying discussion around the model output, thats what the threads about- I havent seen one silly ramping post yet..--- maybe your just imagining it...

S

Edited October 17, 2012 by Steve Murr

[Frosty.]

Some more lovely cold charts with arctic air covering the uk in blues through FI with widespread frosts and wintry showers followed by a high drifting into the residual cold pool over the uk with more frosty nights although the north and west tending to become a bit milder with time. The Gfs 00z op shows a messier transition to a cold spell with very mild air from the south doing battle with arctic air trying to push south and a lot of rain would be the result before the cold air wins, probably a lot of snow for the high ground in scotland in the process and the longevity of the cold spell is less than the gfs 12z yesterday but that run to me was the holy grail for late october and impossible to top, also the 00z gfs ens mean is nowhere near as dramatic as the op run but it still means we have at least got a chance of the first really cold spell of autumn later next week onwards but the early part of next week does still look like being very mild for the time of year.

[shedhead]

Morning can someone please save & attach the GFS 204 europe 500 MB chart so I can run some commentary on it-

Remember the 06z is up next- what will the detail look like around our forecast timeframe...

the 00Z ECm has moved a long way to the GFS this morning but still cluttered with shortwaves - not allowing any firm pattern to develop-

Money still on the GFS...-

S

PS to shedhead- I would just bat it back- noones ramping, just enjoying discussion around the model output, thats what the threads about- I havent seen one silly ramping post yet..--- maybe your just imagining it...

S

Steve - I enjoy your outputs and I'm very impressed by your depth of knowledge, but almost every post you make is either dedicated to cold or the persuit of cold, there is very little if any balance. Anyone whoes posts are dedicated to mild or the persuit of mild readily gets accused of bias (along with all the other silly things like wind up merchant etc) and is asked to provide said balance, so whilst I see merit in much of what you say it's the complete 'cold tunnel vision' that doesn't sit well with me.

[Summer Sun]

WOW-

PTB 3, 6, 8,9, 17,

http://modeles.meteo...-6-1-192.png?18

All monsters

S

Plenty of high pressure there across Europe and the UK

[phil nw.]

The recent GFS operational runs including the 00z have been quite bullish about the Northerly for later next week but they are all against other models at present including their own Ens mean.

Other outputs show the cold outbreak further east and a more anticyclonic and benign spell for the uk at that time.

The analysis of the GFS operational run by Steve is very informative but for the sake of balance and keeping less experienced chart viewers informed it is more desirable to take into account all current output.

It may well be instinct and experience could prove the GFS operational correct with time but at present most of us have to rely on current data overall and what it tells us.

[tcc]

Well maybe as you say the Model Output discussion is for balanced views only, maybe Steve's post and subsequent experiment should be moved to the Winter Discussion thread? Or are we not allowed to talk about cold weather specifically in either thread? Also I certainly wouldn't chastised someone for showing mild only, as in either case it's what the models are showing surely? Can't there be room for all 3 types (cold, warm and balanced)

[phil nw.]

Well maybe as you say the Model Output discussion is for balanced views only, maybe Steve's post and subsequent experiment should be moved to the Winter Discussion thread? Or are we not allowed to talk about cold weather specifically in either thread? Also I certainly wouldn't chastised someone for showing mild only, as in either case it's what the models are showing surely? Can't there be room for all 3 types (cold, warm and balanced)

Indeed it is model discussion.The inbalance occurs when the views of only one model is highlighted.

Nothing wrong in discussing any scenario -cold or mild-but if that one view is not supported across all outputs then i think it`s only right that this is pointed out.

[SMU]

I would hope with how I plan to present the analysis it will appeal to all members-

I am going to frame daily all 4 runs for that timeframe suggested last night & run with it-

Also include the ECM & eventually the UKMO & poss ensembles..

that way we get gibby's model analysis & my analysis on a particular snap shot of a possible event- I am happy to do this on protracted cold spells, snow events, mild events, wind events etc etc

S

[A.J]

A timely reminder...The title of the thread is "The Model Output Discussion" ....i.e discussing what the model outputs are showing, not for a "who's the best poster" competition....

All contributions are welcome in here as long as they are on-topic. Note the key phrase "On-Topic".....Have a look through todays posts and count the amount of on-topic posts...Not very many....So the best advice is this...If you like a post click the 'like' button, no need to post unless one has something on-topic to add.....If you don't like a post, again, no need to post, unless one has something on-topic to add....If one finds a post containing questionable material against the forum posting guidlines, then hit the 'report' button.....

It's not a hard concept to grasp, yet it's amazing how many times it has to be repeated in this thread every winter, and yet some people still just don't get it!!

[chionomaniac]

No more on the subject please.

[BLAST FROM THE PAST]

On topic please Hosts....

06z GFS looks to have the core of the deep LP in the ATlantic a tad further SW, this may have an effect on any potential northerly blast, and indeed the amount of warmth prior to that. Will it be an upgrade on either?

BFTP

[BLAST FROM THE PAST]

Out to 108 and we have no SW over the UK and the LP to north of Iceland is deeper. I suspect a hell of a northerly out of this....but it is the 06z? Before that but can't really see it on meteociel but maybe the warmth a tad downgraded but looks pleasand nonetheless.

BFTP

Edited October 17, 2012 by BLAST FROM THE PAST

[chionomaniac]

Out to 108 and we have no SW over the UK and the LP to north of Iceland is deeper. I suspect a hell of a northerly out of this....but it is the 06z? Before that but can't really see it on meteociel but maybe the warmth a tad downgraded but looks pleasand nonetheless.

BFTP

I suspect that this run is more in line with the ECM. The northerly looks to be protected and deflected by never losing the height to our NNE in the high resolution run - in line with MJO phase 1 for November

[BLAST FROM THE PAST]

Yes Northerly never gets going. C can you post the MJO Novemeber phase 1?

I'm suprised with the Atlantic LP being a tad further SW that we get the 06z outcome.

BFTP

Edited October 17, 2012 by BLAST FROM THE PAST

[Frosty.]

It's not so important that the arctic surge fails on this run because the main ingrediants are all there, just in the wrong order. It looked promising for a while but the mild flow was just that bit stronger and exploited a weakness and really rammed it's advantage home so instead of arctic air covering the uk, we get swamped with moist Tropcal maritime air instead, the main thing is that the arctic air still tries to come south and does affect scotland for a time but the jigsaw pieces don't fit on this run compared to the gfs 00z op. As far as the reliable timeframe is concerned, it does turn a bit milder, actually today is mild with 16c in the southeast, the 6z indicates some rain in the south on sunday which keeps it a bit cooler but monday looks warmer in the far south at 17c although there will still be some rain around.

Edited October 17, 2012 by Frosty039

[Mark Bayley]

Yes Northerly never gets going. C can you post the MJO Novemeber phase 1?

I'm suprised with the Atlantic LP being a tad further SW that we get the 06z outcome.

BFTP

Here you go..

MJO composites can be found here

http://raleighwx.americanwx.com/MJO.html

[Geordiesnow]

No doubt people are going to get hung drawn and quartered if they are going to watch every run too see if the Northerly is still there.

Best to look at the trends, the models are hinting at some sort of cold air to head southwards from the Arctic, the PV does not look like its going to form substantially and we seem to be getting some sort of west based NAO if i'm reading the charts correctly so anything can still happen yet. Would be nice too see some cold air flood into Scandinavia and parts of western Russia too boost the snow cover around there.

Looks like the trend for drier weather has backed away somewhat, looks like what looked decent charts on paper for dry weather are in reality not going to be the case. The trend for warmer feeling conditions is still there though as we will be in TM air on a widespread scale.

[BLAST FROM THE PAST]

Thanks Mark.

The 'visual' difference seems to occur at the t144 point. Interesting slant there from 06z and looking at the MJO......lets see where we go from here. On a personal I like southerly tracking LPs crossing south UK from SW rather than a straight arxtic northerly....there we are I'm not an outright coldie!! As long as the LPs are bumping inmto cold air though :-))

BFTP

[shedhead]

Colder northerlies might or might not transpire in the longer term, but what is looking increasingly likely is a spell of pleasantly warm and somewhat drier weather as we enter the final third of October, which must be welcome by many who have seen nothing but rain for what seems like weeks on end.

[OldMetMan]

Interesting changes in the model output so far today. The GFS and ECM seemed to have swapped places so to speak, with the GFS backing off from its northerly with LP moving in before the coldest air reaches us, whilst the ECM is holding back the LP and showing colder air reaching us.

The GEM has picked up the GFS theme from yesterday by bringing down cold north-easterlies.

There is still quite a lot of consistency in the short- to mid-term amongst the models with the remains of Hurricane Raphael absorbing what is left of our present LP complex. Thereafter, pressure builds to the N and NW.

Looking at the current jet location suggests to me 2 scenarios in the mid- to long-term:

1, In order for the cold air to reach us, there needs to be a more meridional flow over the E of the US and Canada. The existing 500mb high near Greenland would thus be enhanced as warm air heads NE towards Greenland, whilst an extending upper trough develops over the E Atlantic, the UK and W Europe.

2. Alternatively, no major 500mb troughing occurs over N America and the upper trough near us only gets about as far as Scandinavia, and the SW jet pushes back in, as depicted currently by the GFS.

The current upper level configuration still, in my opinion, favours the first scenario. Looking at today's 500mb chart, there are signs of a deepening vortex possibly digging down from the Pacific NW into the W USA which would I think enhance downstream amplification.

At this stage, given the accepted unreliability of the early model runs, and the time frame we are talking about, there is clearly a great deal of uncertainty but the fact that the trend is being shown by more than one model makes me think there is something to it.

I'll see what later runs have to say to see how this forecast trend develops.

Edited October 17, 2012 by OldMetMan

[Methuselah]

Interesting 06Z this morning; still the prospect of an eventual cold blast. But, perhaps not just yet. It seems that the warm air down to our south and east doesn't want budge. Yet!

Now, which would I 'bin' yesterday's 12Z or today's 06Z? Perhaps neither? Sometime in the future, when supercomputers are many times faster than they are today, we'll have continuously-updated model predictions? In the meantime, however, we've only our mind's-eye with which to blend successive outputs...

[Thundery wintry showers]

My feeling about this possible northerly is that there almost certainly will be a southward surge of Arctic air north of 60N, but at this range, it is unclear whether it will penetrate south of that and, if so, whereabouts. I quite often see these blasts shunted to the west or east as we get nearer the time, and with it only being October, the setup has to be absolutely spot-on to bring widespread UK snowfall away from the high ground of Scotland. My current feeling is that the northerly blast will end up too far east, as we keep a weak trough in the mid-Atlantic with high pressure over the top.

Over the last couple of days there has been a trend for a westward movement and toning down of the Atlantic trough towards this coming weekend and early next week. However, it looks like there will be a slow-moving front stuck somewhere over the eastern half of the country, with a mix of sunshine and declining shower activity to the west of it, and the warm dry sunny weather over the near-Continent struggling to make it into our shores. The positioning of the front is subject to revision but it looks to me as if many western areas will get a sunny and mostly dry spell of weather but many parts of eastern and central England may end up grey and drizzly.

[Zakos]

I think there is now definitely the potential for a potent cold spell as October draws to a close.

I think we would need a direct northerly to produce a countrywide snow event, especially to low levels.

A slack airflow is most likely not going to produce snow to low levels at this time of year.

something like this would suffice -

The ECM perhaps starting to lean towards the GFS, but still not showing a northerly. I wouldn't get my hopes up at all until the ECM backs up the GFS.

I believe somewhere in Europe is going to receive a cold blast soon, it is too far out now to say whether the UK will join in on the fun.

Im going to stick my neck out and say we will get a northerly, in terms of seeing if snow will fall to low levels, there is no point at all in trying to guess, because the northerly flow forecast will always be modified right up to 92 hours before it occurs. cut off lows can develop etc.. no point at all in looking at snow potential until it is virtually upon us.

[Met4Cast]

Interesting 06Z this morning; still the prospect of an eventual cold blast. But, perhaps not just yet. It seems that the warm air down to our south and east doesn't want budge. Yet!

Now, which would I 'bin' yesterday's 12Z or today's 06Z? Perhaps neither? Sometime in the future, when supercomputers are many times faster than they are today, we'll have continuously-updated model predictions? In the meantime, however, we've only our mind's-eye with which to blend successive outputs...

Interestingly, the 06z op was the milder of the bunch towards the end of the run

http://www.wetterzentrale.de/pics/archive/ra/2011/Rrea00120111023.gif

More Ensembles going cold than we were seeing yesterday too. Still all up in the air of course, but I think the models are starting to pick up this trend