Model output discussion - 20th Feb onwards

[feb1991blizzard]

16 minutes ago, mushymanrob said:

might change sir... the anomaly charts are only predicting with current data, and they dont suggest a huge greenland high (lasting) , but indeed they might change, but until they do, id have thought the chances of one were low?.  of course these charts are not 100% accurate, and on this occasion might have to adjust to something others have picked up on first.

Yes, my point earlier though wrt anomalies, it is the same data, as long as one understands that FI is for picking up trends then one can garnish the same info from the normal run as from the mean anomaly charts. The other point is on here, most are looking for a pattern change where as a professional meteorologist is basically there to make a general 6-15 day forecast so doesn't need to alter the back end of his forecast too hastily, I think it is crossed wires on here, I would do exactly the same as JH does if it was my living, I don't deny he and yourself are right (coming from a professional angle), people like me are via a range of techniques are trying to predict what the anomaly charts might look like in 48 hours or so, particularly when we think cold spells might be in the offing.

[johnholmes]

1 minute ago, feb1991blizzard said:

 people like me are via a range of techniques are trying to predict what the anomaly charts might look like in 48 hours or so, particularly when we think cold spells might be in the offing.

That is the point though, the anomaly charts are for a 6-10 or 8-14 day 'mean' pattern, so what they may show in 48 hours is not really what I am looking for. Other teleconnections may give an idea of any change IF they are suggesting different to what the latest anomaly shows, but in several years of using them, very rarely. I suspect as you suggest in another part of your post we are coming from different angles. Try the way I do and see what you think, say after 3 months of using them. The test is to you did they show hange when change occurred, did they suggest o change when non occurred, in the appropriate time scales? Using them over, I think 5 or 6 years, I would put their success rate at 70% maybe 80% in the 6-10 day and 60-65% in the 8-14 day. That is in correctly predicting what the Extra 500mb chart shows through the dates/time scales in question.

[Sijmen]

John, is any sort of anomaly correlation done for the 500mb charts? Might be interesting to try.

[feb1991blizzard]

3 minutes ago, johnholmes said:

That is the point though, the anomaly charts are for a 6-10 or 8-14 day 'mean' pattern, so what they may show in 48 hours is not really what I am looking for. Other teleconnections may give an idea of any change IF they are suggesting different to what the latest anomaly shows, but in several years of using them, very rarely. I suspect as you suggest in another part of your post we are coming from different angles. Try the way I do and see what you think, say after 3 months of using them. The test is to you did they show hange when change occurred, did they suggest o change when non occurred, in the appropriate time scales? Using them over, I think 5 or 6 years, I would put their success rate at 70% maybe 80% in the 6-10 day and 60-65% in the 8-14 day. That is in correctly predicting what the Extra 500mb chart shows through the dates/time scales in question.

Yes, I trust you, I wouldn't need to check myself because I know you are telling the truth, ive no reason to disbelieve you, as I say, when there is nothing showing in the 16 day timeframe, my first port of call are the teleconnections guru's on here (the strat charts, the MJO etc), then seeing the ens dip right at the very end (by the law of averages a few will drop before the op) and then the next port of call is the your posts in the morning and hopefully suggesting a change but usually it would have already been suggested in the 15-30 day part of the MO text forecast.

[Daniel*]

I suspect it is not last chance saloon a brief milder blip and down we go..

[feb1991blizzard]

A pasting for large parts of the country showing around 192 on the GFS 12, if a rather marginal one.

[Alexis]

GFS 6z at 192h:

And the latest run:

 

A huge 35mb swing in pressure.

 

[Captain Shortwave]

Different again at the 6-8 day range but I think a result like this would please many.

   

Low 500mb heights with 850s of -6/7C at the start of March, that should deliver some decent home grown convection, snow would likely fall to low levels, especially in the heavier showers. A northerly should follow this too.

A long way off, that said the models are trying to toy with regenerating the Euro trough during week 2.

Interestingly the GEM has found pretty much the same day 8 solution

A rather cold low slips south east through the UK with a ridge building in behind.

Edited February 25, 2016 by Captain Shortwave

[Eskimo]

Deep trough across the UK with cold air embedded, also with light winds = snowfest for some, according to the latest GFS. Wild swings in output, almost polar opposite between the 06z & 12z. 

[feb1991blizzard]

1 minute ago, PerfectStorm said:

Deep trough across the UK with cold air embedded, also with light winds = snowfest for some, according to the latest GFS. Wild swings in output, almost polar opposite between the 06z & 12z. 

Yes but at least there was polar air involved in both!!

[Daniel*]

7 minutes ago, feb1991blizzard said:

A pasting for large parts of the country showing around 192 on the GFS 12, if a rather marginal one.

It is a snow fest alright GFS overdoing it no doubt with snow in Camborne

The s thing is not dead in the water for lowland southern Britain in fact we could be entering the most interesting spell of weather, implying wintry hazards coupled with drenching rain ect in meteorological Spring. Does look unsettled! 

[feb1991blizzard]

Just now, Daniel* said:

It is a snow fest alright GFS overdoing it no doubt with snow in Camborne

The s thing is not dead in the water for lowland southern Britain in fact we could be entering the most interesting spell of weather, implying wintry hazards coupled with drenching rain ect in meteorological Spring. Does look unsettled! 

Looking just at the models and what might evolve after 15 days as well + the strat and MJO and not anyone else's forecasts, I would actually be surprised if there wasn't a right dumping in lowland UK somewhere in March, particularly given the cyclonicity in some runs / timeframe, but its all down to luck

[knocker]

You are wag Daniel.

Grand example of the earlier discussion. A transitional system bringing some wintry cold weather and N/NE winds before.................

But of course this just one run and way out yonder.

 

[johnholmes]

1 hour ago, Sijmen said:

John, is any sort of anomaly correlation done for the 500mb charts? Might be interesting to try.

I am sure there is but cannot think of it at the moment.

[Nick F]

So, the GFS operational continues to churn out eye candy at the end of the medium range, but should we be sceptical of the operational given its bias with steaming the MJO through phase 8 at decent amplitude? Whilst the bias-corrected GFS and ECM take the MJO wave swiftly to the COD.

NCEP GFS:

Bias-corrected GFS and ECM:

Given we are in phase 7 and nearly into 8 and the lag effect from the MJO wave, there may still be enough amplification to develop over the Atlantic over the coming days to bring further bouts of cold arctic air from the north at times. Certainly there has been persistent signal from the extended EPS and EC32 (which updates again tonight) for mean trough over Europe with ridging north at times across the Atlantic, Iceland, Svalbard and even Greenland. There maybe periods of less cold westerly flows - but certainly there are no signs yet of Atlantic zonality becoming established.

I woke up to 8cm of snow in Kent one morning in early April back in 2008, so I wouldn't lose hope, just yet, of not seeing the white stuff again until next season, particularly given the strong likelyhood of the current colder 500mb pattern not changing a great deal as we head into early March.

 

Edited February 25, 2016 by Nick F

[knocker]

 

[Cloud 10]

Nice to see the return of the "black hole"anomaly on the GFS 12z around day 10,and looks to be in the right ball-park when compared to the ECM ensemble mean.and hopefully the ECM op can churn out something similar in the next hour or so.

 

GFS OP...ECM mean..

[Man With Beard]

1 hour ago, Captain Shortwave said:

Different again at the 6-8 day range but I think a result like this would please many.

   

Low 500mb heights with 850s of -6/7C at the start of March, that should deliver some decent home grown convection, snow would likely fall to low levels, especially in the heavier showers. A northerly should follow this too.

A long way off, that said the models are trying to toy with regenerating the Euro trough during week 2.

Interestingly the GEM has found pretty much the same day 8 solution

A rather cold low slips south east through the UK with a ridge building in behind.

Lovely charts and a fair analysis as far as the charts show ... but the 850s has been downgraded so often this year that when I see -6C, I mentally think "-4C". I think we need to see some -8C 850s to have some hope that snow would be the end result rather than cold rain. 

[chris55]

Just got in from work, haven't really caught up on the thread or other output, however GFS at 192 deserves a post lol. Quite remarkable really!

 

Snow about i would imagine!

 

[IPredictASnowStorm]

maybe its not sunday anymore its gonna happen on a monday lol

[feb1991blizzard]

2 minutes ago, IPredictASnowStorm said:

maybe its not sunday anymore its gonna happen on a monday lol

If there is anytime a tonking would occur on this run, here it is.

 

Note the darker colours, when you see those covering a wide area then you have a chance, just an example, obviously that's too far out but if that was showing for Monday then we might have been in business.

[bobbydog]

well, interestingly, the GFS shows snow falling, somewhere in the UK, on EVERY frame of the run from 123hrs onwards, much of it over huge swathes of lowland Britain and yes, even in the SOUTH!

before i'm jumped on, yes i know it probably won't be significant/settle/sun's too hot/there's a meteorite in brazil.... blah blah blah... but i've had approximately 5 minutes of falling snow in 2 years so even a light covering that lasts half a day would be nice!

[Captain Shortwave]

Well the good news is that the ECM has found some amplification.

Yesterdays day 7 chart

A lot better and we seem to be moving back towards a pattern with below average temperatures, though how low is still up for debate and of course the potential for snow (if any).

[nick sussex]

The ECM at T168hrs is not far from the GFS and this is a marked change from its recent trend to flatten the pattern out.

Good to see this change.  Surely the UK snowshield has to give way at some point in the next few weeks.

[bluearmy]

The ECM 12z is very close to the ecmp 00z. That had a snow event day 8 across the southern half of the UK as the trough disrupts whilst the 12z op has it roughly North of a line lpool/Norwich 

not unsupported in in other modelling so one to watch if this becomes the direction of travel.