Model Output Discussion - The Run In To Christmas

[karlos1983]

Well onto the next then. Let's hope Jan 2015 can give us better luck. Would really like to see the continent cool down for a sustained period. Although I'm not sure my nerves could handle an easterly week of model watching

[Banbury]

read all about it....  read all about it.....  ecm suite in greenland over amplification shock !

 

ecm ens mean now in line with naefs. cancel the snow event before new year. the pendulum swing on yesterdays 12z was a last hurrah and the direction of travel prior to this (which the gefs and naefs were already on) is resumed.  of course we have a potential winter storm to contend with and possible snow for the scots/northern hills  (not sustained). we could well be looking at a cool and frosty period to follow but a decent snowfall seems a long shot now.

And ECM is right because ????????????????????

[Duane S.]

Seems virtually all models firming up on a pretty severe storm around the Boxing Day period. The details of which however vary wildly. From a deep depression skirting the far North to one sat out in in North Sea and dropping south. I think it is safe to say this is a genuine case of 'bombing' as that low interacts with the jet.

Met must be glued to this one, a nightmare to forecast at this stage and worth remembering not only will the different placement/intensity solutions of that low have huge implications as to what falls out of the sky where and how windy it will get when/where/duration, it will also have an impact on what happens next.

Upstream, no clear signal yet, all to play for still.

[bluearmy]

And ECM is right because ????????????????????

 

and naefs is right because ?????

 

not saying anything is right marcus - we have lost the disagreement now. we have broad x model agreement (ens). isnt that a reason to have some confidence in the ens charts ? yesterdays 12z suites were notable for their disagreement week 2.  now the ecm has gone to the ncep solution, why shouldnt it be right ?  are they both wrong ??

 

all this based on ens. impossible to use ops week 2 as they vary too much, run to run and we only get ecm/gem to day 10 so it becomes a gfs love in longer term.

[Banbury]

and naefs is right because ?????

 

not saying anything is right marcus - we have lost the disagreement now. we have broad x model agreement (ens). isnt that a reason to have some confidence in the ens charts ? yesterdays 12z suites were notable for their disagreement week 2.  now the ecm has gone to the ncep solution, why shouldnt it be right ?  are they both wrong ??

 

all this based on ens. impossible to use ops week 2 as they vary too much, run to run and we only get ecm/gem to day 10 so it becomes a gfs love in longer term.

Im not saying any are , that is a foolish game. I still remember the Easterly a few years back that ECM was selling us, only to take it away at 72 hours.

[johnholmes]

Well what a feast of weather for genuine weather fans.

Will it won't it with the 'storm' on 27 December with 2 out of the big 3 saying yes and one no.

Further out past 27 December will it get cold, how cold and for how long. Even the anomaly charts seem undecided as they change emphasis.

So plenty to keep us all occupied for sure.

The first one is the deep low predicted by GFS to deepen from below 1010 to below 970mb with what would be truly damaging winds and probably even worse a big storm surge down the N Sea. It has support from UK Met although they show it less deep and further NW on the main output. ECMWF seems to keep it even further NW than UK Met at 144h. The next 24-48 hours look like being a fair sized headache for the forecasting services and possibly quite worrying for folk along some parts of the N Sea coastal belt along with, don't forget the oil rigs in its path. Decisions to be taken soon as to whether to evacuate some of them, possibly closing them down to emergency levels only.

Then to the further outlook, see below for the NOAA idea, now more towards at least a temporary quite deep cold shot, I have no idea how long as the 8-14 suggests it is not so keen on the pattern suggested at 6-10 but that may be the normal 'watering' down at that time scale, see below

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

the version below is that from this morning's ECMWF-GFS output

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Today it is the turn of the ECMWF to suggest a colder spell.

Thus enough variation around a similar theme re 'cold' on these charts to give a less than usual reliability on the actual outcome in my view. Normally after 3-4 days of reasonable continuity I would suggest over 70% probability of the upper pattern being as suggested by NOAA 6-10, this morning I would put it at about 50-60%.

Enjoy the ride folks, play nicely as we all are entitled to our views without any personal digs, and to bobbydog-much relief and apologies for taking it seriously.

[mushymanrob]

Well what a feast of weather for genuine weather fans.

Will it won't it with the 'storm' on 27 December with 2 out of the big 3 saying yes and one no.

Further out past 27 December will it get cold, how cold and for how long. Even the anomaly charts seem undecided as they change emphasis.

So plenty to keep us all occupied for sure.

The first one is the deep low predicted by GFS to deepen from below 1010 to below 970mb with what would be truly damaging winds and probably even worse a big storm surge down the N Sea. It has support from UK Met although they show it less deep and further NW on the main output. ECMWF seems to keep it even further NW than UK Met at 144h. The next 24-48 hours look like being a fair sized headache for the forecasting services and possibly quite worrying for folk along some parts of the N Sea coastal belt along with, don't forget the oil rigs in its path. Decisions to be taken soon as to whether to evacuate some of them, possibly closing them down to emergency levels only.

Then to the further outlook, see below for the NOAA idea, now more towards at least a temporary quite deep cold shot, I have no idea how long as the 8-14 suggests it is not so keen on the pattern suggested at 6-10 but that may be the normal 'watering' down at that time scale, see below

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

the version below is that from this morning's ECMWF-GFS output

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Today it is the turn of the ECMWF to suggest a colder spell.

Thus enough variation around a similar theme re 'cold' on these charts to give a less than usual reliability on the actual outcome in my view. Normally after 3-4 days of reasonable continuity I would suggest over 70% probability of the upper pattern being as suggested by NOAA 6-10, this morning I would put it at about 50-60%.

Enjoy the ride folks, play nicely as we all are entitled to our views without any personal digs, and to bobbydog-much relief and apologies for taking it seriously.

 

yes indeed john, im looking forward to enjoying this coming interesting and varied spell!.

 

id have thought the noaa 500mb charts 8-14 dayer would suggest the gfs has a decent handle on things in that time period, as it suggests a stronger/closer ridge to our near southwest. the ridge appears to drift east between the 6-10 and 8-14 , so supports a cold shot albeit brief followed by the return of the atlantic?

[West is Best]

 

To be honest there might be a northerly following this, but this mornings ens seem to be backing a return to a westerly pattern by New Year.

 

 

 

Here's a curiosity for your Christmas Quizes:

 

Q.: Why when FI is mild is this taken as truth, but when FI is cold it's considered to be out in lalaland?

 

Possible answer: because British cold enthusiasts are pessimists borne of realism. But that doesn't mean it's right every time. I think there's every chance now that this rapid developing cyclogenesis at T114 will be the harbinger for a period of dramatic UK weather.

 

Staying within semi-reliable timeframe i.e. out to T168 I'd say the runs are pretty damned exciting at the moment. We have a milder interlude followed by a cold zip, then a brief (possibly so brief you'll miss it if you blink = UKMO) milder interlude and then a northerly blast that could bring storm conditions and snow, sleet and cold rain.

 

For fans of fun weather what's not to like about this?

[Jason M]

GEFS looking very zonal this morning. Only a couple of ptrbs showing any interest.

The PV looks like ramping up to our North, so I think the evidence is starting to point towards a lengthy period of zonality. Maybe worth waiting until we see the charts tonight, but if assuming that the ridge collapses it's a min of ten days (and that really is the min in my view), until we can see any decent colt potential.

I do think (and I include myself in this) that we have tended to start ignoring the evidence in front of us just because we expect the strat influences to simply do the business. That isn't to say we shouldn't take note of the strat, because clearly we should, but I think it's easy to just assume the PV will be a bust and ignore the trop forecasts which are pointing in the exact opposite direction.

One thing of note to me this last week has been the almost complete absence from the longer range charts of any HLB (aside from the transient Greenland heights). Having scrolled through hundreds of charts out at days 10 to 15 there have been hardly any charts that have showed even a hint of heights to our ne

Edited December 21, 2014 by Jason M

[Polar Maritime]

UKMO take on the Winter Storm.

 

[mushymanrob]

Here's a curiosity for your Christmas Quizes:

 

Q.: Why when FI is mild is this taken as truth, but when FI is cold it's considered to be out in lalaland?

 

because our prevailing winds are from the west...ie mild so are more likely to become reality.

[bluearmy]

Having scrolled through hundreds of charts out at days 10 to 15 there have been hardly any charts that have showed even a hint of heights to our ne

Maybe to our ne Jason, but plenty of HLB in the NH. It's not like there is a strong centred p/v like last winter. just nothing seems likely to affect nw Europe re cold.

[JoeShmoe]

Taking the wide model output as a whole and the trends across the last few days and does indeed looks like a return to a more mobile westerly type pattern into the new year

[West is Best]

GEFS looking very zonal this morning 

 

… ramping  ...

 

there have been hardly any charts that have showed even a hint of heights to our ne

 

Do you mean north-east?

 

Interesting you selected the word ramping

because our prevailing winds are from the west...ie mild so are more likely to become reality.

 

 

I refer the honourable gentleman to the answer I gave just a moment ago  :w00t:

 

Possible answer: because British cold enthusiasts are pessimists borne of realism. But that doesn't mean it's right every time.

 

It's pretty intriguing that posts in far FI, when mild, contain phrases like 'it does look likely …'

Edited December 21, 2014 by West is Best

[Summer Sun]

The storm next weekend could be another weather bomb?

 

This is the pressure on boxing day

 

 

And by 01:00 on the 27th its this

 

[Duane S.]

Here's a curiosity for your Christmas Quizes:

 

Q.: Why when FI is mild is this taken as truth, but when FI is cold it's considered to be out in lalaland?

In all reality the opposite would be more accurate.

When there is no hope of cold (aka this time last year) gefs members will only show zonal(with some transient topplers mixed in)

When there is genuine hope of cold (aka now) gefs will show it AND default zonal.

My point being if we are seeing gefs showing eye candy charts it is for a reason (may not happen of course), if it goes more zonal it often (but not always of course) needs to be taken with a pinch of salt

[Captain Shortwave]

Here's a curiosity for your Christmas Quizes:

 

Q.: Why when FI is mild is this taken as truth, but when FI is cold it's considered to be out in lalaland?

 

Possible answer: because British cold enthusiasts are pessimists borne of realism. But that doesn't mean it's right every time. I think there's every chance now that this rapid developing cyclogenesis at T114 will be the harbinger for a period of dramatic UK weather.

 

Staying within semi-reliable timeframe i.e. out to T168 I'd say the runs are pretty damned exciting at the moment. We have a milder interlude followed by a cold zip, then a brief (possibly so brief you'll miss it if you blink = UKMO) milder interlude and then a northerly blast that could bring storm conditions and snow, sleet and cold rain.

 

For fans of fun weather what's not to like about this?

Possible answer - we can only go by the output shown, if the models were showing cold then my post would be completely different. A brief cold snap following a vigorous depression moving south east through the UK on the 27th-29th before the Atlantic high collapses south east returning us to a westerly pattern. Pretty fair reflection of the model output. Last night I did mention the chance of a wedge of heights in the north Atlantic allow cold to filter to us from the north, but that trend has receded, most notably from the ECM suite. 

Also remember that the surface conditions will be mild until Christmas eve as well.

Edited December 21, 2014 by Captain shortwave

[karlos1983]

The storm next weekend could be another weather bomb?

 

This is the pressure on boxing day

 

 

And by 01:00 on the 27th its this

 

Going by Ian F tweets the Met are giving it a lot of attention. Not going to copy his tweet in here, I'm sure he will pop in at some point.

[Jason M]

Maybe to our ne Jason, but plenty of HLB in the NH. It's not like there is a strong centred p/v like last winter. just nothing seems likely to affect nw Europe re cold.

Yes, a fair comment. It is still an interesting issue though because with a deep area of low pressure forecast to be sat in the southern end of the North sea I'd have expected at least some runs to build in high pressure to our ne in response.

[snowrye]

got to admit as a newbie,i find all this exciting and confusing,how can people find so many variations on the models,one says snowfest,someone else says rain,etc,one things for certain,mother nature will do what she wants,hopefully

a nice snowy spell for me

[IDO]

FWIW the CFS has been hinting at a change in the LR for a few runs. Friday's CFS for Jan: 

 

That although not suggesting anything too blocked in our sector had promise re the bigger picture. However yesterdays run: 

 

Will see if that is a blip, but the trend does not look good. Feb has also flipped to zonal: 

 

ECM mean at d10 is zonal: 

 

Christmas Day still looking cool and dry for nearly all on the GFS 06z:  

 

Boxing Day warm front pushes in midday preceding the LP system (slower and less deep compared to the 0z at the same time): 

 

Edited December 21, 2014 by i'm dreaming of...

[Midlands Ice Age]

The GFSP continues to show the Winter Storm tracking South over the UK around the 27th, Bringing severe gales and heavy rain with blizzard conditions in places and Snow to lower levels even down South. An atrocious spell of weather on the way, But interesting all the same for us weather enthusiasts. I would say until this storm is out the way the Models will continue chop and change, So expect further wild swings from the out-put over the next day or two.

 

 

Not a fan of GFS BUT...

 

The chart above from  the 27th  looks identical to the first one the GFS produced when it first picked up the possibility of a storm over Xmas, four or five days ago.

 

If this happens, it will not have been the first time that GFS has done this.

It would be worthwhile noting for future events.   

 

My other note is that the models seem  gradually to be easing the lows to the west.(looked at over 2-3 days). If this continues we could be forced into the snow threat(even from the ECM),  as it means it would end up over East Anglia at its peak after coming down from the NW..   

 

This system needs watching very carefully. The MO must be sitting around the table moreso than usual this morning!. 

 

As to the future, currently the models don't want to know about a longer term cold shot. I am not too sure, as I still believe that high pressure is showing a desire to park itself over us and build a MLB(Note how it moves in on Boxing Day as soon as a gap appears). If this does happen start to look East as the low drops down and a gap appears above it..

 

MIA

 

Edit Just to mention that Jason M and Karlos have also posted to the same effect  above.....

Edited December 21, 2014 by Midlands Ice Age

[Snowman.]

FWIW the CFS has been hinting at a change in the LR for a few runs. Friday's CFS for Jan: cfsnh-2-1-2015-2.png

 

 

 

That's actually a pretty good mean to me that suggest there is evidence for artic heights to build which pushes systems further south combine that with a -AO then you a have a snowfest north of where the lows track.

[Snowman.]

Much better ridging on this OP run.

 

0z 6z 

[karlos1983]

That low still very much evident in the 06z at 144.

Great example of rapid cyclogenesis