Model Output Discussion - 2nd March Onward

[johnholmes]

this link gives my update on the oft maligned 500mb anomaly charts, how they were 4-5 days ago, what if anything has changed and how the 3 main centres show the charts from last evening, NOAA and this morning ECMWF-GFS, objective as always!

[TEITS]

this link gives my update on the oft maligned 500mb anomaly charts, how they were 4-5 days ago, what if anything has changed and how the 3 main centres show the charts from last evening, NOAA and this morning ECMWF-GFS, objective as always!

http://forum.netweat...20#entry2624820

I do find the anomaly charts useful but in this case they have lagged behind of what was always more likely. Over many days what is being shown on the operationals has always been evident on some of the GEFS ensembles and at times these ensembles have been very few. However my instincts always told me these were right.

Im not bragging here but just highlighting what I said earlier that forecasting is all about looking at the output and then using some forecasting instinct to see what is likely to be correct even if this means backing outliers.

[Ian Brown]

There is certainly plenty of cold air to tap into, should the synoptics fall right, and that's the crux - getting HP in the right place to the NW, we know from experience that such charts need to come within T120 range.

[bluearmy]

Rob,no wonder you are not seeing what some of us are if you are using the anomoly chart you linked to. Thats based on the operational output only. The ens anomlys have been pointing this way for longer than one or two suites.

[Harsh Climate]

Nice charts this morning but you can't help but feel 'if only a couple of months earlyier'.

Still very heavy snowfall could be achieved in parts if the GFS00z was to be believed, but those wanting that dry long lasting powdery snow I feel it's much too late.

[bluearmy]

And there is way too much back slapping at the range we still sit at. I was arguing that the anomolys pointed towards a continental flow since mid week. However, we aren't at the point where far less cold adjustments aren't possible.

[Timmytour]

Whether or not the potential for another cold spell materialises. would i be right in thinking the current developments in the charts are not related to any SSW event? It's just that some of this winter's discussion may have given the impression that we are dependent on one for a cold spell

[High Altitude]

Lets play pin the shortwave on the donkey. I can't remember a cold spell they haven't spoiled and no doubt one will crop up in the models soon. How nice if for a change it would act in our favour.

[Frosty.]

this link gives my update on the oft maligned 500mb anomaly charts, how they were 4-5 days ago, what if anything has changed and how the 3 main centres show the charts from last evening, NOAA and this morning ECMWF-GFS, objective as always!

http://forum.netweat...20#entry2624820

well if it's going to happen, the mo will say something today as the gfs 00z shows it cold for 95% of the uk by next sunday.

[TEITS]

Nice charts this morning but you can't help but feel 'if only a couple of months earlyier'.

Still very heavy snowfall could be achieved in parts if the GFS00z was to be believed, but those wanting that dry long lasting powdery snow I feel it's much too late.

I was thinking the same earlier. However what you have to take into account is blocking as shown by the output will always be more likely in March than Dec/Jan. This is why the Dec 2010 E,ly was so special and why to this day I still get annoyed at missing 45cm of snow by 30miles!

[Tom Jarvis]

Good gfs coming up how close to the uk can we get the -20 cold pool

[TEITS]

What a miserable cold, raw day that would be.

http://www.wetterzentrale.de/pics/Rtavn1501.png

Clear affects of the cold N Sea.

http://www.wetterzentrale.de/pics/Rtavn15017.png

[chionomaniac]

Whether or not the potential for another cold spell materialises. would i be right in thinking the current developments in the charts are not related to any SSW event? It's just that some of this winter's discussion may have given the impression that we are dependent on one for a cold spell

I think that you will find that there is a displacement type warming ongoing / forecast in the strat driven by a large wave 1 event leading to the displacement towards Siberia that you are seeing.

10hPa

100hPA

Not as strong as a SSW event, but certainly significant.

[Frosty.]

What a miserable cold, raw day that would be.

http://www.wetterzen...s/Rtavn1501.png

Clear affects of the cold N Sea.

http://www.wetterzen.../Rtavn15017.png

Excellent charts, bring it on.

[Thundery wintry showers]

I still feel cautious about this possible snowy spell because the GFS and ECMWF are showing what looks suspiciously like a cold cloudy type of east to south-easterly from T+120 to T+192, with some fronts hanging around bringing light rain earlier in that period and then mostly dry cloudy weather, before the snowy conditions set in after T+192. It's still too far out to be able to have much confidence in it.

Sunshine is continuing to be variable, rather than necessarily abundant, during the current quiet spell. Here in North Yorkshire for instance it was grey and chilly on Friday, it was very sunny yesterday, and it is grey again today, and I think this will continue for the next couple of days. The 5th may be a sunnier day generally as we pick up a dry continental flow (as Peter Gibbs had suggested on a couple of recent BBC forecasts) but then from the 6th onwards slow-moving fronts are likely to bring a cloudy spell of weather, albeit with mainly small amounts of rain.

Edited March 3, 2013 by Thundery wintry showers
corrected mis-spelling

[cooling climate]

I think that the 0z GFS was to far west with the block in building heights over Greenland and

that the main core of the heights will be a little further east than that.

If the developments from the 06z run are correct with a portion of the Arctic high moving east

over northern Russia as well as the hights to our north this COULD lead to an exceptional

cold spell. With a portion of the vortex traped over northern Europe and forced to move

west/ southwest, northwest Europe and the UK could see some really frigid cold uppers

(-15c to -16c ) accompanied by heavy snowfalls I would imagine.

In other words this has the potential of becoming a March version of Feb 91 or Jan 87.

[snowmadchrisuk]

The 6z shows us , what happens if the High pressure builds to close to the UK, I think if the Cold spell does fail then this will be the cause... The GFS is swinging wildly at the moment from Snow heaven to boring cloudy weather. If it is going to happen though and we are looking for snow , we do need to see this happen in the next 10 days or the best we will be able to hope for is Falling snow melting when it hits the ground..

Just to add the 6z does get there in the end , but I am not chasing +300 hour charts just as I wouldn't any other time of the year.

Edited March 3, 2013 by snowmadchrisuk

[bluearmy]

The 06z is interesting as it seems to contain all the themes from the recent output. Note the ridge hung out to our east towards the end of high res as per the 00z ecm (not supported too much by the ens inc the control which brought the colder air in earlier). The shortwaves tracking w to e along the pfj where we would see large amounts of snowfall, and the dumbelling sw of the vortex energy around scandinavia bringing renewed pushes of colder uppers interspresed incursions of less cold from the w/nw.

As per chris's post above, there remains some doubt. However, the 00z naefs anomolys among some of the best of the winter fr cold through week 2.

Edited March 3, 2013 by bluearmy

[SMU]

Posted 01 March 2013 - 23:15

Going on from posting over the last few days Im expecting a significant swing towards cold in the 144/168 timeframes of modellling in the next 24 hours.

S

So from operationals like this on the 1st-

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2013030100-0-168.png?0

http://www.meteociel.fr/modeles/ecmwf/archives/2013030100/ECH1-168.GIF?00

The swing to cold is now complete- with the anomaly charts following suit

The ECM & GFS MEANS on the right page-

http://www.meteociel.fr/modeles/ecmwf/runs/2013030300/EDH1-168.GIF?03-12

http://modeles.meteociel.fr/modeles/gens/run/gensnh-21-1-150.png?6

GFS Looks a bit faster-

Looks an exciting few days for one last chance blast of cold, id rather it come with the snow though, dont fancy all that suface chill with no snow!

S

[weather eater]

It never ceases to amaze how people never learn from stuff they see every day, over the last few days we have seen the models gradually back away from a more prolonged spell of milder air, slowly but surely we have seen a trend to undercut and wind direction shift round to the east, in other words the synoptic pattern keeps evolving. This process will, as it does on every day of the year continue to evolve, but yet we see again the same old mistake being made by members once the evolution has shifted round to a colder outlook, they seem to believe that the evolution process will stop, and consequently a colder spell of weather is inevitable, and therefore certain foresighted members need a hearty backslapping. We saw this last month, after two or three fantastically cold runs RS was lauded with plaudits, funny because February turned out to be an unremarkable month. Earlier it was stated that even the best forecasters were not right 100% of the time, frankly it’s nowhere near that and that not because of lack of ability on the forecasters part, although bias towards certain weather patterns by some doesn’t help, mainly its simply to do with the chaotic nature of our weather. Yes good looking charts at the moment but 120hr plus charts are going to change, Ok if it’s cold you are looking for its possible they may change for the better, however, experience suggests the opposite happens 95% of the time. Rather like the much touted prospects in February I will happily take a bet that we will not see much in the way of prolonged cold or snow. I have the deepest admiration for those that understand synoptic evolutions but when it comes down to working out what is and isn’t likely to happen, experience, critical thinking and a lack of bias helps more often than not.

Edited March 3, 2013 by weather eater

[Ian Brown]

Top post WE, I feel that any transition to colder uppers will depend on the position of the Low pressure to the SW and how long it hangs around, we need to see this slip away to allow an easier transition to E/NE winds, as well as any block to the NW to be positioned correctly and not be put under any immediate pressure from the Atlantic.

So plenty of hurdles to cross and I don't fancy watching those hurdles being crossed at the Cheltenham festival with snow coming down !

[SMU]

It never ceases to amaze how people never learn from stuff they see every day, over the last few days we have seen the models gradually back away from a more prolonged spell of milder air, slowly but surely we have seen a trend to undercut and wind direction shift round to the east, in other words the synoptic pattern keeps evolving. This process will, as it does on every day of the year continue to evolve, but yet we see again the same old mistake being made by members once the evolution has shifted round to a colder outlook, they seem to believe that the evolution process will stop, and consequently a colder spell of weather is inevitable, and therefore certain foresighted members need a hearty backslapping. We saw this last month, after two or three fantastically cold runs RS was lauded with plaudits, funny because February turned out to be an unremarkable month. Earlier it was stated that even the best forecasters were not right 100% of the time, frankly it’s nowhere near that and that not because of lack of ability on the forecasters part, although bias towards certain weather patterns by some doesn’t help, mainly its simply to do with the chaotic nature of our weather. Yes good looking charts at the moment but 120hr plus charts are going to change, Ok if it’s cold you are looking for its possible they may change for the better, however, experience suggests the opposite happens 95% of the time. Rather like the much touted prospects in February I will happily take a bet that we will not see much in the way of prolonged cold or snow. I have the deepest admiration for those that understand synoptic evolutions but when it comes down to working out what is and isn’t likely to happen, experience, critical thinking and a lack of bias helps more often than not.

To be fair weather eater if your moaning at what was taken as a given then you are guilty of that yourself as it sounds like your moaning at your own frustrations- a bit like siberian bloke was the other day-

If by now you cant grasp the fact that theres an element of change & variability right up to 24/48 hours away then its you im afraid that hasnt learn anything.

The ECM showed -10s across the UK at day 9- what actually landed was -13c uppers, what was missing was the instability factor.

What we have learnt is that ECM tends to push the easterly flow further west & the model bias seems to correct further south with time- so thats what needs to be considered this time around-

S

Edited March 3, 2013 by Steve Murr

[bluearmy]

Tbh steve, the ecm ens werent far away on friday mornings runs. If you can be bothered, you can check the past ten days on ecm website. this current situation is far removed from the previous spell when the ecm op made the running, consistent with the undercut in the face of lack of ens support. the ens have signalled this before the ops have got consistent on it. now we come to the difficult bit where we try and advect an unstable cold pool over us. Better option than the meeting of fronts and cold which is too knife edge and only means heavy snow for part of the uk.

[weather eater]

To be fair weather eater if your moaning at what was taken as a given then you are guilty of that yourself as it sounds like your moaning at your own frustrations- a bit like siberian bloke was the other day-

If by now you cant grasp the fact that theres an element of change & variability right up to 24/48 hours away then its you im afraid that hasnt learn anything.

The ECM showed -10s across the UK at day 9- what actually landed was -13c uppers, what was missing was the instability factor.

What we have learnt is that ECM tends to push the easterly flow further west & the model bais seems to correct further south with time- so thats what needs to be considered this time around-

S

Not so much a moan as an observation and I'm not frustrated or at least not with the weather, I do get frustrated when people can’t see what’s obvious, I'm a coldie but I don’t have mood swings biased on what weather is coming my way that would be childish. I agree however with your last statement.

Edited March 3, 2013 by weather eater

[Ian Brown]

To be fair weather eater if your moaning at what was taken as a given then you are guilty of that yourself as it sounds like your moaning at your own frustrations- a bit like siberian bloke was the other day-

If by now you cant grasp the fact that theres an element of change & variability right up to 24/48 hours away then its you im afraid that hasnt learn anything.

The ECM showed -10s across the UK at day 9- what actually landed was -13c uppers, what was missing was the instability factor.

What we have learnt is that ECM tends to push the easterly flow further west & the model bais seems to correct further south with time- so thats what needs to be considered this time around-

S

Well as we know the instability wasn't there (generally) because of the proximity of the High to the UK, it didn't matter how cold the upper air was or what the time of year was, if the core of heights is over Northern Scotland then the pattern is too far South for the sort of unstable snowy easterly of yesteryear.

This is probably different because HP will be orientated differently and probably to the NW.