Model Discussion 12Z 25/02/13

[Methuselah]

Well the 12z gfs op run is full of cold weather but just not for the uk.

Always the way?

[johnholmes]

The gfs 12z GFS which has solid support from the UKMO shows why those ruling out any cold from the east shouldnt rush into it. The outcome is plausable, it also shows why those 500 mb charts that john uses arent as great as they first appear, much the same as december.

The small area of + VE heights over the NE will be poorly modelled and moved around, even removed- thus rendering some of the anomaly runs useless

S

sorry to keep harping on but

in December I did a whole pdf to show that had I or anyone else for that matter paid close attention to them they gave 4 or it may have been FIVE days warning of the cold spell not happening.

But best left alone for now.

ALL data needs to be used and assessed, I've lost count how many times I've suggested this. You have to be aware of which type of model output is, with statistics to show they are, best for particular time scales. We all have our favourite model to use, folk can see over months or years how they and the models they use give results or not.

Maybe we should run a contest with different folk using different models to see which over several months gives the most accurate forecast. Obviously over the same time scales. The checks to be done by several other folk NOT involved with the model tests?

happy to do my bit with guess which models!

[Polar Maritime]

Always the way?

Not always just 99% of the time :-)

[Panayiotis]

GFS ensembles at 144hrs not going with what the UKMO is showing regarding the shortwave above Norway:

http://www.meteociel...&mode=1&ech=144

I say this because the UKMO may not be able to build heights to the NE like the GFS,ECM and other models are showing. If that shortwave remains there it would once again scupper our chances of getting an

easterly.

We want that shortwave to swivel round the low to the SW therefore allowing the heights to build, many of the members show this, for example:

Edited March 1, 2013 by Panayiotis

[Frosty.]

Not always just 99% of the time :-)

The amazing thing about the gfs 12z is that during the course of the run at some point there is very cold air to the west, north and east of the uk but our little island misses it all, what do we have to do to get another cold spell, maybe we will have a white easter this year.

Peter Gibbs just showed some orange arrows pointing at the uk from early next week with winds from the med heading our way.

[TEITS]

Sorry but I have noticed how you have a go at mr holmes and i'm sure he does look at all the data, not just the 500mb anomaly charts, come on teits, you should know better, john is vastly experienced and says things as they are, just as gibby does. As for the models, the chance of any worthwhile cold seems to be diminishing and it's the large rainfall totals later next week we should now focus on!

How exactly was I having a go at John? All I did is query why John is puzzled why some are looking for cold synoptics.

Anyone ruling out the chance of cold returning in the next two weeks is being premature. The outlook is looking very uncertain but at the moment cold is more likely than mild with an outside chance of being exceptionally cold for the time of year into week 2 of March.

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=319&ext=1&y=74&run=12&runpara=0

[chris55]

How exactly was I having a go at John? All I did is query why John is puzzled why some are looking for cold synoptics.

Anyone ruling out the chance of cold returning in the next two weeks is being premature. The outlook is looking very uncertain but at the moment cold is more likely than mild with an outside chance of being exceptionally cold for the time of year into week 2 of March.

http://modeles.meteo...un=12&runpara=0

The GEFS have been all over he place recently in FI (as you might expect) but those 12z ens are showing the coldest set for mid March I have seen. Obviously lots of scatter but those very cold runs are notable for the time of year, so worth watching how things develop.

[TEITS]

hi Dave

Oh but I do look at anything I can get hold off. Just because I usually quote the anomaly charts does not mean I am not looking at everything

The point I am trying to make is that no matter what synoptic charts show until the upper air shows the favourable pattern then there can be no cold pattern.

MJO is in 6 which suggests heights being centred over Europe(south), with a rather weak link from there towards Iceland but no major blocking to the north of the UK.

The AO has been -ve for some time as has the NAO and with both in the semi reliable time frame shown as remaining at or below the zero line, so one would imagine that should be helpful in stopping a raging Atlantic. Indeed the anomaly charts suggest this type with the main flow being south of 50N.

All 3 anomaly charts show blocking, in terms of +ve heights, which are not necessarily 'real' is well north and having little direct impact on the UK weather.

So no I NEVER take any one chart or set of charts in isolation so apologies if my post gave that idea.

I stand by my suggested probability of lasting cold developing in a 15 day time scale as 10% or less.

Fair enough John but I still stand by my earlier point that im surprised your puzzled at some of us suggesting the chance of cold synoptics. You say little direct impact but inactual fact some of the GEFS ensembles do suggest this.

The chart below certainly shows a direct impact as do a few other ensembles.

[Frosty.]

How exactly was I having a go at John? All I did is query why John is puzzled why some are looking for cold synoptics.

Hi dave, it's not the first time you have been critical of John, I have a good memory, the point is your post made him sound like he only checks the 500mb anomaly charts which of course is nonsense, I think you are just disappointed that he doesn't see any particularly cold potential in the current output.

[TEITS]

Hi dave, it's not the first time you have been critical of John, I have a good memory, the point is your post made him sound like he only checks the 500mb anomaly charts which of course is nonsense, I think you are just disappointed that he doesn't see any particularly cold potential in the current output.

No it isn't the first time and over the years I have been critical of other members posts, so what this is what discussion is all about. Sometimes you disagree and other times you agree. If you check the seasonal thread I was very complimentary about Johns forecasting techniques.

As for your disappointed comment and to be honest I expected better from you. I stated a few days ago that once I get to this time of year I welcome mild or cold. At the moment for Week 2 of March the outlook suggests cold if you look at the ensembles I posted.

[chionomaniac]

And back to the models now please.....

[Frosty.]

No it isn't the first time and over the years I have been critical of other members posts, so what this is what discussion is all about. Sometimes you disagree and other times you agree. If you check the seasonal thread I was very complimentary about Johns forecasting techniques.

http://forum.netweat...d/page__st__320

As for your disappointed comment and to be honest I expected better from you. I stated a few days ago that once I get to this time of year I welcome mild or cold. At the moment for Week 2 of March the outlook suggests cold if you look at the ensembles I posted.

In that case I apologise, I haven't been in the seasonal thread, hope we can move on from this now.

[Cheese Rice]

GFS ensembles have switched to cold again after somewhat dropping the signal. Although I don't have much faith in their output as it can be very fickle it does at least show the route to cold and what to look out for.

The three best below

What is pretty clear from most models is that some exceptionally cold air is looking odds at pushing into NE Europe, how far south the cold air pushes and whether it can be advocated west remains to be seen.

Edited March 1, 2013 by Cheese Rice

[Cloud 10]

GFS ensembles have switched to cold again after somewhat dropping the signal. Although I don't have much faith in their output as it can be very fickle it does at least show the route to cold and what to look out for.

The three best below

What is pretty clear from most models is that some exceptionally cold air is looking odds at pushing into NE Europe, how far south the cold air pushes and whether it can be advocated westw remains to be seen.

May as well chuck the control run in there as well.

[TEITS]

Shame the JMA isn't more reliable.

Big freeze coming on that run and its a shame it stops at +192 because +240 would be bitterly cold from the NE.

[Frosty.]

A mild and eventually unsettled looking Ecm 12z op run after a benign start to next week with ridge conditions and increasingly mild SEly winds from the med, those winds eventually veer more Sly and then SWly as the controlling low becomes positioned to the west of the uk, so in summary, fine at first with more widespread sunshine as the milder drier SEly winds pick up, then as the high continues to slide away southeast we become more unsettled and remain mild.

[J10]

Latest Ski Blog now out

http://forum.netweat...1st-march-2013/

Good weather to be skiing in, but not so good for snow retention.

[Gibby]

Good evening. Here is the report from the 12z outputs from GFS, UKMO and ECM for today Friday March 1st 2013.

All models show High pressure close to NW Britain. Over the coming days it drifts down over the UK and eventually away Eastwards over Europe early next week. The rather cloudy and benign conditions currently affecting most of the UK will last a while yet before brighter and drier air moves NW from Europe on a slowly freshening SE breeze early next week. The South will become somewhat less cold too benefiting from a more Southerly aspect to the air flow.

GFS then shows Low pressure to the West of the UK later next week with Southerly winds over all areas and troughs of Low pressure affecting the UK too, especially in the West where rainfall could become heavy and persistent at times, though much less for more North-eastern areas. Through FI tonight there is something for everyone as unsettled and changeable conditions continue for many. Day to changes could be quite marked with a chillier interlude followed by milder weather again with rain at times on SW winds shown to end the run.

The GFS Ensembles show some milder weather to be enjoyed over the next week once the stubborn cloud inversion is displaced early next week. However, some rain will follow and there is good support for uppers to fall away again later in the run with the Control dropping the UK back into the freezer though thankfully it is an outlier while the operational is an equal outlier though of the milder variety.

The Jet Stream shows no change in it's Southern arm blowing strongly East over Southern Europe while the Northern arm stays weak and unobtrusive while the High pressure remains in place.

UKMO for next Thursday shows a SSE flow over the UK with Low pressure out to the West. Some rain would be expected for all with the South and West seeing the heaviest and most prolonged outbreaks of rain. It should feel rather milder for most though.

ECM shows an altogether milder outlook tonight with the SE flow of early in the week veering Southerly later. However, the price to be paid is that rain will develop from midweek with all areas at risk but the West seeing the heaviest outbreaks. Towards the end of the run the pattern of Southerly winds remain with mild temperatures and further bursts of showery rain at times.

In Summary tonight there are changes afoot and some areas of the UK will welcome them with open arms even if the price to be paid is some rain at times. The cold, cloudy conditions that have become synonymous of most peoples weather over the last week or so is set to change early next week. Clearer skies will push NW early in the week with milder air lifting temperatures well into double figures over Southern Britain by midweek. Pressure will be falling and Low pressure closing into the West of the UK will introduce some rain at times, at first in the South and West but to other areas too later with Southerly winds persisting over the UK.

[Frosty.]

Well I thought with a southerly tracking jet and a strong southern arm and a weak northern arm, the uk would stand a better chance of having a cold and unsettled pattern but the ecm 12z op run is rather springlike out to T+240 and nothing like the potential of the 00z at day 10, still, the ecm op could be a mild outlier and we may just get lucky on the next run. Tonight's ecm is good for gardeners and growers with some milder sunnier weather followed by mild and wetter weather and no frost.

[Frank Trough]

Shame the JMA isn't more reliable.

http://www.meteociel...92-21.GIF?01-12

Big freeze coming on that run and its a shame it stops at +192 because +240 would be bitterly cold from the NE.

funny how it still gets posted when it shows cold, though! I doubt anybody would be popping a JMA chart in that showed a below average but far from cold set up.

but that, to me, looks the form horse. I can't really see anything to be excited about whatever you "want". I am bracing myself for a period of completely unremarkable weather for March to be honest. The ECM at t+192 just about sums it up:

wet, uninspiring, feeling cold but not really cold.

Edited March 1, 2013 by Pharaoh Clutchstraw

[Frosty.]

Shame the JMA isn't more reliable.

http://www.meteociel...92-21.GIF?01-12

Big freeze coming on that run and its a shame it stops at +192 because +240 would be bitterly cold from the NE.

It's a shame all the big freezes this winter have only existed in deep FI of any particular computer model but especially the ecm, and never come close to verifying.

[Evening thunder]

funny how it still gets posted when it shows cold, though! I doubt anybody would be popping a JMA chart in that showed a below average but far from cold set up.

but that, to me, looks the form horse. I can't really see anything to be excited about whatever you "want". I am bracing myself for a period of completely unremarkable weather for March to be honest. The ECM at t+192 just about sums it up:

wet, uninspiring, feeling cold but not really cold.

At least it looks a lot more interesting than the recent/current spell of weather, some actual weather activity should be happening! some rain/showers, and possibly spring like sunshine at times, rather than just endless grey nothing happening days like the south has had to endure for what seems like ages.

[bluearmy]

seems to be one of those periods when the operational seems to be plucked from one of the members of the previous suites' ens members. until we see some consistency on the ops, i think we'll struggle to pin down the nw european pattern middle third march.

cpc anomolys still promoting energy running to our south though with slack upper flow pattern, not sure too much should be read into what that infers. not much different to yesterday (as usual). my thoughts remain as they were although low in confidence. several operational runs from the day did reflect what i summised from the cpc data last night.

[Cloud 10]

Maybe stronger signs of a ridge of high pressure towards Greenland on tonight's CPC 8-14 dayer

compared to yesterday's?

yesterday.. today..

12z Ecm ensemble mean anomalies seem quite bullish on this.

[mushymanrob]

sorry, i know im a mildy, but a big freeze?or remarkable cold spell?c,mon guys until theres one being shown consistently within a reliable timeframe the chances are incrdibly remote . ill believe it when i see it, and its a possibility that it might happen. but atm theres no sign on the models, and whilst the ensembles might point to something colder, isnt that just cherry picking?.

that facts are that atm the models do not show any appreciable cold for us. it might change, it might not.