Model Output Discussion - 21st - 28th November

[No Balls Like Snow Balls]

euro high, has Europe moved then?

The centre of the +ve anomaly seems to me to be over Scandinavia?

If we cannot even work out where something is then there is precious little chance of interpreting the models correctly.

my apologies if its my old eyes that are at fault.

The other valid point to make is it is at T+384.

How many times does the model even remotely get the correct idea that far out?

I do agree about asking questions on here. I'm a touch surprised that OON should make this comment. I would agree if someone asks a succession of questions that is best dealt with by pm but asking questions is how we all learn.

Well my young eyes tell me that preceding T384 the high starts to build in Central Europe and moves North, would that not be a euro high as central Europe seems to be it's origin.

As far as I know Scandinavia has not moved out of Europe and become a new continent.

I don't think I said it would come off at T384, a misinterpretation by you there i think, all I said was is I will keep an eye on it to see if it appears in days to come.

Edited November 22, 2011 by No balls like Snow Balls

[November13]

Umm NAEFS has us back with the euro high by the end of the first week of december.

Round 2 anyone?

I shall be keeping a very close eye on this in the coming days to see if this continue's to be modeled on NAEFS.

I can only assume that this time around it maybe a slightly cooler high?

in the meantime we should enjoy the upcoming autumnal weather.

Totally agree, if it is a question about models, what to look out for etc or how a certain factor will affect the models then it should be asked in here. But that's not rocket science to realise that surely.

-3c in Scotland and 12c in northern Scandanavia in December..must be April Fools already. Mind you it has been spring like!

Edited November 22, 2011 by November13

[johnholmes]

Well my young eyes tell me that preceding T384 the high starts to build in Central Europe and moves North, would that not be a euro high as central Europe seems to be it's origin.

As far as I know Scandanavia has not moved out of Europe and become a new continent.

I agree the two areas have not moved-but what you have to look at is once the synoptic situation is as shown by the chart you displayed have a look at where the air is then feeding from. Airmass characteristics do change when moved from one pace to another.

perhaps an illustration of this is in the chart below, the red line traces where the air has originated from?

the other point I was trying to make in my post is that the chart you displayed is at the farthest reaches of synoptic chart outputs. It has, I would suggest, on 8 years or so of watching GFS outputs every day, a less than 10% chance of being anywhere near correct. GFS has had some incredible successes but its rare for it to be correct that far out.

The chart I showed at T+?? forget whether its 72 or 96 hours, could also be wrong, but statistically its far more likely to be correct.

[shedhead]

-3c in Scotland and 12c in northern Scandanavia in December..must be April Fools already. Mind you it has been spring like!

Those are not temperatures... opps, should have said refer to the learning area in case to OONanator is looking...

[johnholmes]

Those are not temperatures... opps, should have said refer to the learning area in case to OONanator is looking...

yes if I can try to explain for those who may not be clear about what the chart shows

The chart being shown is NOT a temperature chart but the 500mb height anomaly chart. This shows how the NEAFS model at that time scale is suggesting the heights at 500mb may be in terms of the average expected at that time of year.

Edited November 22, 2011 by johnholmes

[Zakos]

Those are not temperatures... opps, should have said refer to the learning area in case to OONanator is looking...

In all fairness, the charts are fairly misleading as they show negative anomalies in blue, and positive anomalies in red, easy mistake to make IMO, as this what you would expect with a temperature anomaly chart.

[Isolated Frost]

-3c in Scotland and 12c in northern Scandanavia in December..must be April Fools already. Mind you it has been spring like!

As shedhead says, they of course are not temperatures. They are geopotential height anomalies. Seems very mild for the UK, maybe less so at night if a continental influence strengthens.

[shedhead]

yes if I can try to explain for those who may not be clear about what the chart shows

The chart being shown is NOT a temperature chart but the 500mb height anomaly chart. This shows how the NEAFS model at that time scale is suggesting the heights at 500mb may be in terms of the average expected at that time of years.

In essence wrong for cold dominance but right for mild dominance.

[johnholmes]

As shedhead says, they of course are not temperatures. They are geopotential height anomalies. Seems very mild for the UK, maybe less so at night if a continental influence strengthens.

IS I suspect you might be mixing up the definitions.

It does not show mild over the UK simply that there is no change in the 500mb height over the UK compared to the average expected at 500mb not the surface remember?

[Zakos]

For temperature anomalies, use this animation (GFS) http://policlimate.com/weather/current/gfs_t2m_anom_eur_f.html

[johnholmes]

oh dear we do seem to be getting a bit mixed up here.

The values shown on the NAEFS chart have nothing to do with what temperatures may show at the surface, day or night time, mild or cold. They are differences from the average of the 500mb height

[Isolated Frost]

IS I suspect you might be mixing up the definitions.

It does not show mild over the UK simply that there is no change in the 500mb height over the UK compared to the average expected at 500mb not the surface remember?

Yes I know that- but high 500mb's to the east and low to the west generally indicate a south/south east flow?

[johnholmes]

Yes I know that- but high 500mb's to the east and low to the west generally indicate a south/south east flow?

sorry IS-your comment is correct, usually-as ever with meteorology there will always be the exception; lots of factors to consider to arrive at a forecast for temperature even with that pattern you describe

[shedhead]

sorry IS-your comment is correct, usually-as ever with meteorology there will always be the exception; lots of factors to consider to arrive at a forecast for temperature even with that pattern you describe

Yes, it's not possible to make a definative forecast for the surface off of that chart, but you can very safely say (faux cold excepted) it's far more condusive to average/mild conditions. Were the anomolous heights being shown as the other way around, then it might be time to get rather more enthused/positive about some proper Winter.

[chionomaniac]

I don't think that I have seen such average ensembles before.

[Isolated Frost]

sorry IS-your comment is correct, usually-as ever with meteorology there will always be the exception; lots of factors to consider to arrive at a forecast for temperature even with that pattern you describe

Sorry for not elaborating on the original post

[WhiteFox]

It's been a strange year. I don't think I can remember a year where a Euro high has dominated quite so much, with the notable exception of the summer months. Reviewing a brief selection of charts from each month of this year so far, we've had some form of blocking over Europe fairly closeby pretty regularly. I remember back in late February when the cold high over Northern Europe was teasing for quite some time without every visiting. Then of course we had the settled and notably warm periods in March and April. Come September, the Euro high first built and since then it's been remarkably resilient, only occasionally shifting slightly to allow low pressure systems move further south. There have been a number of occasions where the models have projected an unsettled outlook over a two week period for the whole of the UK, only for this to be scaled back to less than a week. I'm struggling to remember the last time we had a two week period of classic Atlantic weather of Low Pressure, ridge, Low Pressure over a two week period.

Looking at the latest ensembles for London (I acknowledge that the North and West have seen more unsettled weather), we are again starting to see the projection of a two week unsettled spell of classic Atlantic weather. I'm not looking for cold weather here, so I'm unbiased! Anyway, the GFS ensembles are projecting unsettled weather for London from the 25th through to the end of the run. Over the past few months, this has quickly been scaled back as high pressure quickly rebuilds and rebuts any attempts by further low pressure systems from over-running Northern Europe (it would be interested to see rainfall anomalies for Northern France, Germany etc.).

I'm left wondering if we're going to see the same happening again with this pattern change?

Yes, it's not possible to make a definative forecast for the surface off of that chart, but you can very safely say (faux cold excepted) it's far more condusive to average/mild conditions. Were the anomolous heights being shown as the other way around, then it might be time to get rather more enthused/positive about some proper Winter.

I'm sure you used the term "faux cold" deliberately to annoy John (Actually, I'm not too keen on it myself!).

It's surface cold, as it is definitely cold, albeit not to any great depth...

[nick sussex]

I've been searching around for a few positives for cold lovers and comments from NOAA were a bit more hopeful.

NEARLY ALL GUIDANCE TO VARYING DEGREES INDICATES A

BUILDING EPAC/WEST COAST RIDGE

Thats from the morning discussions which can be found here:

http://www.hpc.ncep....epd/preepd.html

This is important if it amplifies sufficiently as this could effect the downstream pattern in Europe. We still though have the problem of lowish heights to the north but anyway lets see what wonders the GFS has in store for us this evening.

Generally an east Pacific/west USA coast ridge correlates with high pressure in the Atlantic, this has already been suggested by that area of high pressure near Newfoundland, the problem is though whether this will set up too far west and keep the UK on the milder side of the trough.

Edited November 22, 2011 by nick sussex

[BLAST FROM THE PAST]

I'll have a go then... If the first 3 weeks of June 2020 are close to record breakingly hot, the last week will be cooler.

Shed not if the 4th week was record breakingly hot, also if 2nd or 3rd week was cold and warmth came back on 4th week? Fact that he is relating to is that there was no forecast cool down, cold, whatever, likely IMO with my outlook of any change until the last week and there hasn't been. The relevant temp remains well above average at present. The timing of the change is satisfactory and to add I have never called for serious cold or snow. So lets move on, you I seem to remember thought the rut would continue well into Dec? Ok just read later post, we have to wait until into Jan for winter? Ok

Looking good for a to and fro Dec IMO with a bit of everything thrown in [including winter].

BFTP

Edited November 22, 2011 by BLAST FROM THE PAST

[mountain shadow]

The biggest positive for me is that it's only the 22nd November, still 8 eight days till winter proper. Subtle signs of warming in the stratosphere, perhaps a little more amplification in the jet. We've been in worse places than this before.

[shedhead]

Shed not if the 4th week was record breakingly hot, also if 2nd or 3rd week was cold and warmth came back on 4th week? Fact that he is relating to is that there was no forecast cool down, cold, whatever, likely IMO with my outlook of any change until the last week and there hasn't been. The relevant temp remains well above average at present. The timing of the change is satisfactory and to add I have never called for serious cold or snow. So lets move on, you I seem to remember thought the rut would continue well into Dec? Ok just read later post, we have to wait until into Jan for winter? Ok Looking good for a to and fro Dec IMO with a bit of everything thrown in [including winter]. BFTP

Decembers are normally to and fro with a bit of everything thrown in, but it will still end up average to mild from what I can currently see...you I assume, as I asked earlier are saying average to cold?? Edited November 22, 2011 by shedhead

[Bobby]

Another very unsettled zonal run on the 12z GFS. Plenty of rain about

[No Balls Like Snow Balls]

Another very unsettled zonal run on the 12z GFS. Plenty of rain about

Some much needed and welcomed for the South if it came off

[Bobby]

Chilly too, this at 168 :o

Edited November 22, 2011 by Barb-

[nick sussex]

The GFS in the higher resolution output is slightly more encouraging than the 06hrs run but as you can see its hard going to get the troughing sufficiently south and east to get that colder air into the UK.

The UKMO isn't so good IMO as its developing that shortwave more off the eastern USA at 144hrs, we really need a big shunt east and south in the pattern, will we get it?

Lets hope so.