Jump to content
Sign in to follow this  
phil nw.

Model Output Discussions 18z 31/01/2016

Recommended Posts

20 minutes ago, Man With Beard said:

Just to add to John's post - for easy comparison of runs, you can use Meteociel's "archive" options; here is the GFS link: http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&carte=0&mode=0&archive=1&runpara=0

On to the current charts - the period 10th-12th February has been the recent focal period for cold, and the GFS 06Z shows a fairly cold set-up at this point:

gfs-0-204.png?6

Control run isn't too far off:

gens-0-1-192.png

GEFS ensemble mean is also pushing heights up to Iceland

gens-21-1-216.png

Pretty cold

222-583UK.GIF?03-6

ECM ensembles not falling over themselves in support, but some members supporting a colder period around this time

ensemble-tt6-london.gif

OK - moving from the cold to the wind - the ECM ensemble wind chart nicely demonstrates how the GFS completely overblows lows in comparison to the mean. See if you can spot the GFS 00Z on this chart (Clue: It's the one that goes off the scale at the top ;) )

ensemble-ff-london.gif

 

Sorry I am not sure it does follow on from John's post. He said to keep to within the T144 time frame none of those images are within that time frame. From his post I thought the point was to compare the same Time stamp frame from different runs, 0z Monday Tuesday and today for example, not pick and mix. I apologise if I have miss read your post but it did not seem me to follow on from John's post

Share this post


Link to post
Share on other sites
5 minutes ago, EastAnglian said:

Sorry I am not sure it does follow on from John's post. He said to keep to within the T144 time frame none of those images are within that time frame. From his post I thought the point was to compare the same Time stamp frame from different runs, 0z Monday Tuesday and today for example, not pick and mix. I apologise if I have miss read your post but it did not seem me to follow on from John's post

I think he meant the link to the GFS archives.

Share this post


Link to post
Share on other sites

Thanks alexisj9 in that case apologies MWB but it did seem that the link was connected with the output you showed which confused me, But that is not difficult 

these days. :)

Share this post


Link to post
Share on other sites
1 hour ago, johnholmes said:

Folk can take this or ignore but it might help some of you that are relatively 'new' to model watching.

Beyond about T+144 hours do NOT compare each new run to the last one, such as 06 to 00. Nine times out of 10 at those ranges you will get variations from run to run. To get some coherent idea using just the GFS or ECMWF or any other model compare like with like. Compare the 06z this morning with that from yesterday. Is there some kind of consistency? If there is then the model may be picking p a consistent signal. Then look at another time output, 00 or 12z and see if either of them are showing a similar consistent pattern. If they are then it would be fair to assume that the model at all 3 times has probably got the overall pattern correct. Detail would become more apparent as T+00 approaches. If this pattern seems to fit the overall upper air pattern that others are showing, in my case, the anomaly charts, then it is a pretty good indicator that the indicated weather pattern will evolve.

Try it over a few days to see how you feel about it.

Hello John,

It would be really helpful to understand the rational to viewing the charts in this way. I can think of 2 possible reasons, but maybe there is a third.

1. Anything beyond 144 is too far out for the models to grasp properly, therefore you should always expect changes at this range between the same timed runs?

2. Different data sets are fed into different runs throughout the day?

However, I do wonder that if it is for the first reason, then as long as the models (regardless of which run it is), are showing a similar outcome, then the likelihood of that outcome is just as likely?

Thanks in advance

David

Share this post


Link to post
Share on other sites
1 hour ago, EastAnglian said:

Sorry I am not sure it does follow on from John's post. He said to keep to within the T144 time frame none of those images are within that time frame. From his post I thought the point was to compare the same Time stamp frame from different runs, 0z Monday Tuesday and today for example, not pick and mix. I apologise if I have miss read your post but it did not seem me to follow on from John's post

Just to clarify, the follow-on from John's post was the link to archive charts, by which you can easily compare past runs. The rest of my post was entirely my opinion of the models, nothing to do with JH. 

Share this post


Link to post
Share on other sites
34 minutes ago, Theresnoway said:

 

Hello John,

It would be really helpful to understand the rational to viewing the charts in this way. I can think of 2 possible reasons, but maybe there is a third.

1. Anything beyond 144 is too far out for the models to grasp properly, therefore you should always expect changes at this range between the same timed runs?

2. Different data sets are fed into different runs throughout the day?

However, I do wonder that if it is for the first reason, then as long as the models (regardless of which run it is), are showing a similar outcome, then the likelihood of that outcome is just as likely?

Thanks in advance

David

hi David

I tend to feel it is both 1 and 2 you quote having an effect. If you use the same run each time then the same or very similar data sets are being used so at least one variable is being removed. Over the years it seems to work quite well. Not perfectly, nothing in meteorology ever does. But you will get a better 'feel' for how well any model is dealing with a situation at any time of the year doing it the way I suggest. There is some truth in your final paragraph as well. All I can suggest is you use it over some months and see what it appears to show you.

Share this post


Link to post
Share on other sites

On another matter, the last comment I made about what I would anticipate the overall weather being in the 6-15 day time scale is the wind strengths with any or at least one or two of the systems the upper flow would develop, very windy with them and possibly severe gales close to any surface low track. Just where those tracks may be=probably fairly close to NW Scotland at times. A small possibility that one 'might' track a bit further south but this is for the synoptic models for this kind of detail.

 

Edited by johnholmes
spelling again!

Share this post


Link to post
Share on other sites

Oh  well looks like  glossea has dropped the signal for a colder later part of feburary  and more into a zonal set up  wet and windy i think is the words to discribe the next few or more weeks.  and maybe some transiant  snow

Share this post


Link to post
Share on other sites

Hi all, any thoughts on the potential Storm Imogen? The Met Office don't seem to be buying it at present?

Share this post


Link to post
Share on other sites

I've been rather pre-occupied this morning but I must say it is remarkable to see such major disagreement between GFS and UKMO/ECM with respect to the disturbance at just +96 hours... will we have a monstrous storm to contend with Sun/Mon/Tue, or a shallow wave?! :cc_confused:

The uncertainties only become worse after that of course, as yet another energetic low runs up the Eastern Seaboard and interacts in some way with a shortwave low leaving the U.S. in 5 days time. 

I like the idea of the shortwave dashing away from the E.S. runner, but only because of that massive snowstorm potential as it runs into the cold air on the rear flank of the departing UK trough. Not that it worked out very well on the GFS 00z det. for me in the far south! 

It's a throwback to when ECM and a couple of the higher-res models teased such an interaction - but on a smaller scale - for the day we're about to reach (or it may even have been for today?).

 

It's enough to keep my entertained in my spare time while the models figure out to what extent the Canadian polar vortex will rise from the grave and cause trouble in the 8-14 day range.

As much as the model seem keen to do that, the stratosphere at 30 hPa for example doesn't look very supportive and in fact suggests low heights should tend to transfer back to our E/NE again before long:

npst30.png

BUT this is a recent development as GFS has trended toward a greater advance of the warm anomalies across the U.S. and toward the W. Atlantic. So a few days is needed to ensure that's not a wobble from the model as it comes to terms with how the minor SSW will play out.

Good consistency from the past two runs, though, even out to +16 days, which is encouraging:

npst30.png npst30.png

It's not ideal as again there is more of a west-based negative NAO potential than east-based when looking at that alone.

This, however, is without the MJO propagation through the Pacific that ECMWF and the likes of NOAA are expecting to begin 2nd half of Feb. That could quickly shuffle the cards in favour of blocking near to our NW or N... hence my concerns over a big delay to spring this year.

 

Share this post


Link to post
Share on other sites
1 hour ago, Man With Beard said:

Just to clarify, the follow-on from John's post was the link to archive charts, by which you can easily compare past runs. The rest of my post was entirely my opinion of the models, nothing to do with JH. 

Thanks MWB but I had already realised that and posted an apology, but thank you for the clarification. The models seem to be flipping and flopping with each run at present, I spent a little time this morning comparing the 06z runs and to my eyes there is little consistency. It is a little like if you don't like what they show wait until the next run and it will be different.

Share this post


Link to post
Share on other sites
38 minutes ago, weirpig said:

Oh  well looks like  glossea has dropped the signal for a colder later part of feburary  and more into a zonal set up  wet and windy i think is the words to discribe the next few or more weeks.  and maybe some transiant  snow

Where has this come from? Haven't read latest METO long range if that's where it's from!!

just read long range, your right!! Bring on the summer and fingers crossed next winter brings something better. Towels in I think!!

Edited by Ali1977

Share this post


Link to post
Share on other sites

Looks like the minor stratospheric warming we are having now has no real effect on the troposphere and the positive NAO and AO, and still we have abnormally low pressure over N atlantic without reasons

Has it been even snow laying on the ground a whole day in London this winter? I haven't seen anything when looking at webcams etc

Share this post


Link to post
Share on other sites
5 minutes ago, Faronstream said:

Looks like the minor stratospheric warming we are having now has no real effect on the troposphere and the positive NAO and AO, and still we have abnormally low pressure over N atlantic without reasons

Has it been even snow laying on the ground a whole day in London this winter? I haven't seen anything when looking at webcams etc

Last 3 winters never mind this one - not in the city centre anyway!!! 

Share this post


Link to post
Share on other sites
18 minutes ago, EastAnglian said:

Thanks MWB but I had already realised that and posted an apology, but thank you for the clarification. The models seem to be flipping and flopping with each run at present, I spent a little time this morning comparing the 06z runs and to my eyes there is little consistency. It is a little like if you don't like what they show wait until the next run and it will be different.

Yes I certainly agree with that. We would need to see the pattern I highlighted repeated a few times before any confidence could be gathered. However, the GFS very rarely shows north Atlantic ridging inside D10, so the 06Z was noteworthy for that. Can the 12Z repeat it? We're about to find out...

Share this post


Link to post
Share on other sites
38 minutes ago, Ali1977 said:

Where has this come from? Haven't read latest METO long range if that's where it's from!!

just read long range, your right!! Bring on the summer and fingers crossed next winter brings something better. Towels in I think!!

Also  fergies quote on the strat thread     what a borefest this winter as been

Share this post


Link to post
Share on other sites
39 minutes ago, Ali1977 said:

Where has this come from? Haven't read latest METO long range if that's where it's from!!

just read long range, your right!! Bring on the summer and fingers crossed next winter brings something better. Towels in I think!!

From strat thread.

1 hour ago, fergieweather said:

Meant to post this morning, but was busy - latest GloSea output has now lost (entirely) the colder anticyclonic signal last week of Feb. Now looking very mobile/zonal to close the month (and winter). Indeed, any drier, colder phase circa 10-12 Feb looks tenuous, with now only small minority ENS support. So, most likely outcome - despite any stratospheric/MJO influences - is the rest of Feb resolving overall as either average or slightly above for temperatures; frequently unsettled/windy/wet, but with periodic passing colder phases. Clearly, that means some snow (even further south) remains quite possible at times.

Meanwhile the 12z

gfsnh-0-162.png?12

Edited by SN0WM4N

Share this post


Link to post
Share on other sites

Horrible MetO update for coldies, especially away from he North, which flips from drier colder second half of Feb to unsettled and milder than average. Let's hope it changes back.

ECM has been relentlessly poor but GFS has thrown up some interesting synoptics and this 12z run already looks to have more Winter interest than 06z

gfsnh-0-144.png?12

So although no proper cold spell in sight there remains the possibility of some widespread snowfall to low levels though may not settle and even if it does propbably won't stick around - still beggars can't be choosers

 

Also decent UKMO 144 with that runner low set to cross the south of the UK which would bring snow for some and some amplification behind,

UN144-21.GIF?03-17

For all the doom and gloom (and I feel the same) the second week of Feb could turn out to be the snowiest of the Winter for many although with the caveat that may be snow falling rather than snow settling away from high ground.

Edited by Mucka

Share this post


Link to post
Share on other sites

V muted in this thread.

I'm unsure whether Ian F could spill some insight but the GFS seems rather keen on a channel runner mid next week, quite some consistency on this. 

Virtually windless ideal conditions for evaporative cooling.

image.thumb.png.396753ed73c0be37948b3b39image.thumb.png.80c0ec6620bfd0a65c4b0827image.thumb.png.59d84afbccb101dda6be52bdimage.thumb.png.8a39c91b0af4568603f73c0b

Share this post


Link to post
Share on other sites

Why does everyone takes the long range forecasts for granted I shall never ever know, for me personally, I could not care less what it says or what the background signals may say etc, its what the models shows what counts. 

I've seen forecasts on here saying that December could be interesting for cold, then January could well be interesting and it was for 1 week of the month if albeit snowfall was fairly limited and came via an unusual set up(certainly if you look at the chart at face value, then you would never think it would be a chart that would bring snowfall) and then there was quite a lot of hype about February, so far, the hype is completely unjustified but I won't be throwing in the towel just yet though, we know the weather is never quite that simple hence long range forecasts should never be taken as gospel whatever they say.

Anyways, still potential for a deep low to hit the UK but it would seem the severity of it won't be as bad as the last 2 named storms but its definitely look like it will be more southern areas that will be affected and for that reason, I would suspect the UKMO might class it as a named storm. I'm surprised some members are hoping there would be no deep low but it is winter after all and for me, if you can't have the snow then severe gales is no doubt the next best thing. 

Share this post


Link to post
Share on other sites

a general observation......why do people take long range or even mid range modelling as gospel?........like many others, I've read Ian's posts pertaining to the meto's models and mid range/seasonal models (and value his input as well as several other knowledgeable posters) but I've noticed that even the meto's models chop and change as they're all computer sims reliant on the initial data entered.............The weather will do what the weather will do, no computer simulation will influence the outcome 1, 2, 5, 10, or even 100 days from now......so "winter's over" type posts are utterly irrelevant......by all means discuss all the model outputs, after all, this is what the thread is about, but don't take the predicted output as gospel, 'nailed on' etc etc, or you'll drive yourself mad! :)     (I used to, and look at state of me now.....barking mad! :crazy: )

Edited by ajpoolshark

Share this post


Link to post
Share on other sites

Certainly more support for better amplification upstream this evening although any ridge looks like being toppled at the moment

GEM

gemnh-0-210.png?00

Share this post


Link to post
Share on other sites

Although this chart looks OK

Rtavn1981.gif

There is very little to suggest any reasonable snow potential for the south

Rtavn1987.gif

Welsh mountains, northern uplands & Scotland in with a chance

Rtavn19817.gif

A frosty spell for a while

Rtavn21017.gif

Edited by Purga

Share this post


Link to post
Share on other sites

Wales is looking right in the firing line for most of next week on the latest GFS run as from early Sunday morning onwards

gfs-2-84.png?12

gfs-2-114.png?12

gfs-2-186.png?12

gfs-2-192.png?12

 

Edited by andymusic

Share this post


Link to post
Share on other sites
2 minutes ago, andymusic said:

Wales is looking right in the firing line for most of next week on the latest GFS run as from early Sunday morning onwards

gfs-2-84.png?12

gfs-2-114.png?12

gfs-2-186.png?12

gfs-2-192.png?12

 

The Midlands getting involved on there as well.... interesting but at that range unlikely... but never say never.... still just have a feeling something is gonna come out of the blue during the next 4 weeks...

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  

×
×
  • Create New...