Model Output Discussion - 16th Jan 12z onwards - Smile While You Post!

[Captain Shortwave]

A distinct correction West on tonight's 120hr fax when compared with the raw data of the earlier 12z.

http://www.meteociel.fr/modeles/ukmo2.php?carte=2000&ech=0

Actually that is showing yesterdays 120hr chart still

This is todays

The occluded front has cleared the east coast by this time, low pressure still near Iceland and elongating a little.

General thoughts are that it is still pretty cold and the front would likely bring a mix of rain, sleet and snow (how much of what can be debated until tomorrow morning when the models will change again)

We get a good few cold days out of this, and there is snow being shown to fall in places. So there is still interest, even if the easterly has become a distant dream for now.

Edited January 16, 2015 by Captain shortwave

[Fred Sykes]

Well 1947 it ain't, but still a wintry looking 5 days, which is good considering where we were a couple of weeks ago!

I don't buy into the opinion that now we're nearer the reliable time frame the models won't revert back. At the moment I'd say the reliable time frame is about T6. Subtle changes can have a big affect the outcome in this present situation.

[Long haul to mild]

Last night's 18z and tonight's for next Thursday :

That's a flip, whichever way you look at it.

Yes, I know the signs were there beforehand, but it hardly fosters much belief in model output does it?

[Gibby]

Actually that is showing yesterdays 120hr chart still

This is todays

16-120h.gif

The occluded front has cleared the east coast by this time, low pressure still near Iceland and elongating a little.

General thoughts are that it is still pretty cold and the front would likely bring a mix of rain, sleet and snow (how much of what can be debated until tomorrow morning when the models will change again)

We get a good few cold days out of this, and there is snow being shown to fall in places. So there is still interest, even if the easterly has become a distant dream for now.[/quote

Oops apologies. Yes that looks much like the raw data.

[blizzard81]

A distinct correction West on tonight's 120hr fax when compared with the raw data of the earlier 12z.

http://www.meteociel.fr/modeles/ukmo2.php?carte=2000&ech=0

They look pretty much identical to me.

[Gibby]

A distinct correction West on tonight's 120hr fax when compared with the raw data of the earlier 12z.

http://www.meteociel.fr/modeles/ukmo2.php?carte=2000&ech=0

Sorry guys. It's apparently last nights fax not updated but the timeline has

[weather eater]

Actually I don't think that's true either, it's just we don't notice or when dealing with a large low pressure systems maybe several hundred miles across its going to hit us anyway despite any corrections north south east or west this on the other hand

was always a fine line to tread

 

As it stands the evolution will continue but I doubt whether that will mean it evolving back to something more favourable for a prolonged cold snap for a little while at lest. Still 6 weeks of winter still to come and early spring can deliver some potent snaps.

 

I would say the can be reliable up to 192 hours in a strong Westerly zonal pattern, throw in a hint of blocking and that drops to 72/96 hours.

Edited January 16, 2015 by weather eater

[khodds]

Last night's 18z and tonight's for next Thursday :

gfs-2015011518-0-168.png

gfs-0-144.png

That's a flip, whichever way you look at it.

Yes, I know the signs were there beforehand, but it hardly fosters much belief in model output does it?

But it's NEXT THURSDAY... 6 days away? Bookmark this post, copy it, whatever, and next Thursday look back on it - what happens in reality will be completely different to both of those scenarios Edited January 16, 2015 by khodds

[Mucka]

Sorry guys. It's apparently last nights fax not updated but the timeline has

 

LOL well that has me even more confused because it looks like the 12z to me, is it just cache thing and we are looking at different charts?

 

 

I will put them side by side and have a butchers, should be easier to compare.

 

ECM London ensembles not very pretty I'm afraid.

 

Edited January 16, 2015 by Mucka

[Pat Kennedy]

I think the GFS 18Z is not to be believed the same way I didn't believe it last night, if by Sunday and all the models are singing from the same hymn sheet all well and good, but I suspect we'll see a change tomorrow maybe not what we would like to see but better than tonight's run. 

[throwoff]

For the pub run its not that bad.

For some regions the snow risk is a lot higher Sunday through to Monday than it has been.

I'll save any really worries till the morning and into the 12z

[MR EXTREMES]

this maybe the time to stand back a little from todays nwp. NOAA cpc comment that upstream, they are very unhappy with continuity from yesterday and have low confidence in the current output. the overall pattern has lost some amplification which moves it too far east for us to stay in the action for very long. what if upstream is wrong today on the nwp and tomorrow sees the amplfication return in the models ? it wouldnt be the first time that we see a bit of tooing and froing prior to the onset of a cold period.

 

perhaps the booing and gnashing of teeth should wait another 12 hours? maybe 24. after all, most wise posters indicated tomorrow evening as being when we would get a decent handle on the track of the trough.

It has to be said the models spent 3 days worth of charts of increasing cold and wintry conditions even last night then today a flip beyond belief.

Upgrades tomorrow 12z or Sunday 6z lets see if we can salvage some wintry prospects a weeks worth would be fantastic to be honest.

U can see the uncertainty in the ao index as well which would suggest there split with no agreement there.

[Long haul to mild]

But it's NEXT THURSDAY... 6 days away? Bookmark this post, copy it, whatever, and next Thursday look back on it - what happens in reality will be completely different to both of those scenarios

I can't disagree with you, you are very likely correct, but while the detail will always change, you would hope that at 6 days away that the overall pattern would be correct.

I'm still a learner and this has been an object lesson to me in not trusting outputs that are not zonal based as all the models seem to struggle with them.

[Froze were the Days]

Last night's 18z and tonight's for next Thursday :

gfs-2015011518-0-168.png

gfs-0-144.png

That's a flip, whichever way you look at it.

Yes, I know the signs were there beforehand, but it hardly fosters much belief in model output does it?

Totally agree! - ECM/GFS handled the spell just after xmas pretty poorly as well, a few runs failed on the Greenland high and then  a Scandi high building which again never happened.

[karlos1983]

Difference between gfs 18z and 12 z is staggering and at just 150 hours!

 

.

 

 

I wouldn't worry too much just yet. 1. it could be a massive outliar we need to see the esembles before passing any judgement on 1 isolated run.  and 2, if the gfs can chop and change so drastically from run to run should it really be trusted?? ; )

Hmm, I get what your saying with runs chopping a lot, but the trend is clear, which is away from a deep prolonged cold spell or prolonged cold spell. The writing is on the wall for me, anyone hoping to wake up to the Stella runs of 48 hours ago, i'd suggest you lower your expectations, it's not often we see a reverse back to cold of that degree after a climb down at this stage. Plenty of chances to come with it only being mid Jan, but this should act as a reminder that t96 max is fantasy land in these setups, why did we all (including myself) trust chats that were 5-6 days away? probably down to the fact they are the best charts we've seen for some considerame time. Some will see snow over the next few days but the prolonged cold spell is done and dusted now for me. I'll happily eat my words if I'm wrong, but I very much doubt it.

[Mucka]

Unbelievably there are at least half a dozen runs that just push the low East to the North of the UK that make the Op look like a COBRA run.

BUT

There are also still some decent runs out there which are the ones i will post for.

 

 

[SE Blizzards]

It has to be said the models spent 3 days worth of charts of increasing cold and wintry conditions even last night then today a flip beyond belief.

Upgrades tomorrow 12z or Sunday 6z lets see if we can salvage some wintry prospects a weeks worth would be fantastic to be honest.

U can see the uncertainty in the ao index as well which would suggest there split with no agreement there.

 

I don't want to be the bearer of bad news as everyone clearly knows i am one who ramps cold weather up 'if' it is showing in the charts, but there wasn't much uncertainty in the updated AO forecast today. Most members were clearly in Positive territory towards the end.

 

 

Maybe you were going by yesterday's update which saw a lot of scatter?

 

Anyway, as a true die hard coldie it has been quite a poor day of model watching today. I really hope things change for the better tomorrow.

Edited January 16, 2015 by SE Blizzards

[SMU]

Just adding to my 'upgrade comment earlier'

 

here its really highlighted by the depth of the 850;'s

 

the 18z GFS last night tracking the low in the northern atlantic had entrapped cold uppers but not 'that cold'

 

see here

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2015011518-1-96.png?18

Note the upper ahead of the front has embedded -2c air with the 0c isotherm tracking close to the SW coast...

 

Now the 18z tonight. JMA which has the slider further north but aligning quite well-

 

http://www.meteociel.fr/modeles/jma/runs/2015011618/J84-7.GIF?16-18 

looks at the depth of upper air cold feeding into the rear of the system straight off the Greenland shelf....

 

Also because of this look at the locale of the 0c isotherm - Portugal.....

 

 

What this essentially means is the frontal track isn't as essential as before- you can sit on the western side of the frontal band but still be in snow.

That's because the heights remain low & the front has occluded with -6 uppers from behind

 

This NW type flow following on behind the front is the total inverse of why is doesn't snow in a westerly for the bulk of the UK, upper air westerlies normally don't mix the cold air down to the surface at all well so even though -6c upper Is seemingly set for snow the surface air is usually modified upwards to much-

In the slider scenario the surface air is already modified to very cold levels in the 900-1000Mb layer of the atmosphere & the lapse rate is probably still DALR -

as a result if we still get a decent angle it wont turn to rain Especially for the E/ N / NE & Scotland...

 

take this ensemble from the GFS not far from the means across the day but a veritable snow fest for the most...

 

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=126&code=9&mode=0&carte=0

 

18z JMA also pretty good out to 84

http://www.meteociel.fr/modeles/jma.php

 

Cheers

S

Edited January 16, 2015 by Steve Murr

[weather eater]

Completely understand why people think of back flips but you only get out what you put in. contrary to popular myth the models do not work from past experience only from pure maths based on the input data and that does not stand still, charts are effectively out of date before the number crunching begins so in truth I'm always amazed by how good they are. But it is frustrating when people expectation get raised by seeming model consistency.

[throwoff]

Great post.

As always snow is 80% nowcasting if not more.

Leeds had heavy snow fall today as did other bits of the nation and that wasn't really modeled in advance by any of the runs.

Everything can change for the 06z and the 12z I frankly see some regions having quite an upgrade on the 18z

[karlos1983]

I don't want to be the bearer of bad news as everyone clearly knows i am one who ramps cold weather up 'if' it is showing in the charts, but there wasn't much uncertainty in the updated AO forecast today. Most members were clearly in Positive territory. 

 

 

Maybe you were going by yesterday's update which saw a lot of scatter?

 

Anyway, as a true die hard coldie it has been quite a poor day of model watching today. I really hope things change for the better tomorrow.

Yep doesn't make pretty reading. I challenge anyone to argue the case for prolonged cold against those charts along with the 12z and 18z....... Good luck!

[Mark Neal.]

In the shorter term Euro 4 updated. Midlands and then pushing SE in the morning, Sleet-Snow. Also to the NW and Scotland/Ireland still.

[summer blizzard]

GFS is extremely progressive tonight with westerlies by day 8. Euro still has northerlies 

 

GEM has the middle ground with the Azores and Scandinavian High fighting each other (UK dry and cool in the meantime) however by day 10 the GEM has the Russian High just about beating the attempt (you can see the front has been bent below) before the next low approaches.

 

[Cloud 10]

The NOAA discussions highlight the flip-flopping we are seeing in the model output at the moment.

 

MODEL UNCERTAINTY REMAINS VERY HIGH IN THE WEEK-2 PERIOD. THE 00Z ECMWF
ENSEMBLE MEAN TEMPERATURE TOOLS INDICATE LESS CONFIDENCE THAN YESTERDAY'S
FORECAST, WHILE RECENT RUNS OF THE DETERMINISTIC GFS HAVE YIELDED EVERY
IMAGINABLE SOLUTION OVER THE CONUS. CONTINUITY BETWEEN RUNS OF THE ECMWF AND
CANADIAN ENSEMBLES HAS BEEN BETTER AND THOSE SYSTEMS ARE IN GOOD AGREEMENT WITH
EACH OTHER. THEREFORE, THOSE TWO SOLUTIONS CONSTITUTE A GOOD MAJORITY OF THE
MANUAL BLEND.

 

Full discussion here.

 

 http://www.cpc.ncep.noaa.gov/products/predictions/610day/fxus06.html

[Long haul to mild]

Hmm, I get what your saying with runs chopping a lot, but the trend is clear, which is away from a deep prolonged cold spell or prolonged cold spell. The writing is on the wall for me, anyone hoping to wake up to the Stella runs of 48 hours ago, i'd suggest you lower your expectations, it's not often we see a reverse back to cold of that degree after a climb down at this stage. Plenty of chances to come with it only being mid Jan, but this should act as a reminder that t96 max is fantasy land in these setups, why did we all (including myself) trust chats that were 5-6 days away? probably down to the fact they are the best charts we've seen for some considerame time. Some will see snow over the next few days but the prolonged cold spell is done and dusted now for me. I'll happily eat my words if I'm wrong, but I very much doubt it.

Sadly, I think you are correct, the charts were so good they simply HAD to be right! There's too much *reasonable* model consensus now to believe anything other than this is unlikely to be the big snowy spell it could have been.

However, there are definitely snow chances for folks over the coming days and still plenty of winter left to get that elusive East wind!

Edited January 16, 2015 by Long haul to mild