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

[jello]

Excuse this post if im an idiot lol

 

But.. I have recently starting following the models and starting to get my head round everything and get the hang of reading them. But one thing, could someone tell me what times they all update at?

 

Also is it looking good for NI?  as earlier it was forecast to be rain in the east but now Northern Ireland weather have warnings out now for accumulations for most areas.  

 

Does this precipitation chart support it?  Am I right, please give me a gold star if I am  or if il an idiot please don't tell me off

 

Edited January 19, 2015 by jello

[Paul]

Excuse this post if im an idiot lol

 

But.. I have recently starting following the models and starting to get my head round everything and get the hang of reading them. But one thing, could someone tell me what times they all update at?

 

Also is it looking good for NI?  as earlier it was forecast to be rain in the east but now Northern Ireland weather have warnings out now for accumulations for most areas.  

 

Does this precipitation support it?  Am I right, please give me a gold star if I am  or if il an idiot please don't tell me off

 

Welcome to the model thread Jello - you can find the timings here:

 

https://forum.netweather.tv/topic/72242-model-output-update-times/

 

Note the GFS runs a little slower since it's recent upgrade though

[SMU]

Just to defend Ian /METO post a little-

 

The MET office was waiting for a little more continuity from the model clusters before releasing any warnings-

There was both track deviation in the models & temperature issues making it difficult to forecast ( as well as problems with the moisture plumes associated with the front)

 

The met office do need to put out some high likleyhood low to moderate risk amber warnings now.

 

I would go with Midlands & some of the Shires.

 

My forecast track has been blended WEST- as elluded to last night...

 

Wiltsure, Staffordshire, Northamptonshire, Warwickershire, Cheshire + oxforshire could be the big winners today-

 

the 'on the cusp zones I highlighted last night' may have lost the battle.

 

30 odd hours to go yet...

 

S

Also NI looking good.....

Edited January 19, 2015 by Steve Murr

[Nick L]

Just a reminder that there is a cold spell thread to discuss the forecasts of tomorrow night's event:

 

https://forum.netweather.tv/topic/82292-upcoming-cold-spell-discussion/

[Captain Shortwave]

The 06z shows some slight changes in how the first set of fronts act against the cold block. East Anglia and Kent are pretty much never going to feel any effect from the front now. As Steve says central and Northern England look good as a rough guide.

Still the chance of a few wintry showers pushing into eastern areas on Thursday (850s do drop to -8C in places so snow is a possibility, though the length of the easterly looks short)

As for beyond that, we have the usual shortwave off the west of Norway developing and the next system doesn't disrupt enough over the UK so the precipitation on Friday falls mainly as rain (snow on hills)

Edited January 19, 2015 by Captain shortwave

[West is Best]

The huge standoff continues.

 

GFS = widespread snow

 

 

vs

 

UKMO: "snow confined to hills in the north" (direct quote)

 

http://www.bbc.co.uk/weather/

Added the very last link because it includes the latest Met Office thinking, based on the UKMO's output.

 

It's a brave person that bets against the Met Office fax charts and forecasts this close. Which will yield? I still think looking at the angle of frontal attack (see the fax chart) and the rising uppers that the Met Office are right, but it's a borderline event either way.

Edited January 19, 2015 by West is Best

[bluearmy]

The picture for week 2 seems to be a reasonable call for mobility to return from the west. Whether thats pm/tm alternating or a nw/se axis jet delivering mainly pm with further chances of disruption depends on the orientation of the Azores ridge. The extended ens seem unwilling to offer good continuity, run to run so I think vagueness is a good place to be for the time being.

[West is Best]

Just to defend Ian /METO post a little-

 

The MET office was waiting for a little more continuity from the model clusters before releasing any warnings-

There was both track deviation in the models & temperature issues making it difficult to forecast ( as well as problems with the moisture plumes associated with the front)

 

The met office do need to put out some high likleyhood low to moderate risk amber warnings now.

 

I would go with Midlands & some of the Shires.

 

 

 

They are going the other way at the moment: "snow confined to hills in the north" is the latest word. Can't recall a model output and therefore forecasting standoff on this scale for a long time.

[Timmytour]

As for beyond that, we have the usual shortwave off the west of Norway developing and the next system doesn't disrupt enough over the UK so the precipitation on Friday falls mainly as rain (snow on hills)

Am I right in thinking that pesky shortwave was there all last winter and effectively prevented any movement west of Scandinavian airmass?

[Nick F]

So, 06z GFS says ok for snow away from the SW of England as the occluded frontal system slides SE across the UK.

 

 

Nevertheless, don't assume it will pan out like that, the picture is complicated across the south by a developing shallow surface low along the trough axis across SW England early Wednesday ... GFS drops the low SE into NW France, whilst ECMWF and UKMO move the low east through the Channel/far S of England.

 

So Weds snow potential for the more marginal south (S of Midlands) will depend on:

 

 1. Models factoring in some mixing as the frontal system arrives with strengthening flow to increase surface temps. But if they do not have the degree of accuracy yet with the angle of approach of the fronts nor development of that low along the front across the SW early Weds, this will ultimately have an affect on the wind direction ... i.e. a more backing the flow as per ECMWF low moving east along Channel as opposed to a more onshore flow with GFS dropping the low into France. This can make a big difference to some areas being on the  wrong side of marginal for snow (onshore milder flow from S or SW) or right side of marginal (calm conditions or backing flow tapping into cold pool to the north or east).

 

2. How the stagnating cold pool across the UK recovers temp-wise during daytime today and Tuesday. Sub-zero temps over the next few nights under clear spells, a ridge of high pressure building in today combined with areas of cloud from decaying fronts trapping cold air at the surface ..., may lead to models perhaps over-estimating daytime temps over next few days.

 

3. If it's still a marginal knife-edge snow/rain situation in some areas (particularly south of the M4)  - will the precip be heavy enough to allow evaporative cooling to lower the snow level? ECMWF precip looks light, though surface temps look reasonable, GFS a little heavier.

 

Ultimately, nowcasting will be the best way of determining which side of marginal certain areas will be for snow/rain

Edited January 19, 2015 by Nick F

[frosty ground]

Am I right in thinking that pesky shortwave was there all last winter and effectively prevented any movement west of Scandinavian airmass?

That "Pesky" Short wave is a symptom not the cause of issues.

[West is Best]

hi west... (richard isnt it?)

given that the predictive charts are notoriously unreliable, maybe the met o / bbc are more likely to be accurate?

 

Hi Rob,

 

Yes I think they're right. For me it's all about the frontal angle. It's wrong for a widespread snow event off a north-westerly approaching low pressure system. That's my opinion, that's all, but you can see it on the fax chart output and the MetO's current forecasting.

 

This may be wrong, and fwiw I'm not even an amateur meteorologist (as Steve Murr is). I wish these model outputs looked different, but to me this week looks cold but mostly not-white.

 

best, Richard

Edited January 19, 2015 by West is Best

[Captain Shortwave]

Am I right in thinking that pesky shortwave was there all last winter and effectively prevented any movement west of Scandinavian airmass?

I think ultimately it shows that there is still portions of the jet running north east as well as south/south east into France. As Frosty ground's post says it's a symptom of the split flow rather than the cause. If all of the elongated trough sunk south east then that short wave would not be there.

Edited January 19, 2015 by Captain shortwave

[West is Best]

Really fine post Nick (as ever) but should the words below be added to the NW swear filter?

 

south of the M4

Edited January 19, 2015 by West is Best

[ItNeverSnowsInWindsor]

GFS charts show snow for much of West Yorkshire on Wednesday. BBC and Met Office show nothing but dark cloud on Wednesday. *shrugs*

Are you sure ?? On the Met Office site it shows snow for Yorkshire from Tuesday evening into Wednesday, some of it heavy.

[Timmytour]

Just a note of caution for those either expecting no breakdown of the cold or just a temprorary breakdown of it.

The last few pages of this thread, for about the same time last year, were also full of hopes

https://forum.netweather.tv/topic/79144-model-output-discussion-19th-january-2014-18z-onwards/page-131

Hopefully this year is a completely different proposition <fingers crossed>....nevertheless there's the similar talk of evolution set ups and NH pattern changes boding well for the future....

[Eugene]

Well back to frosty nights next monday on GFS 06Z, looks to me that sw'ly flow later on sunday/monday is going to get squeezed the closer we get.

[TEITS]

Thought I would compare todays 06Z with yesterdays!

 

1035mb high over Scandi

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2015011806-0-240.png?6

 

Today a 975mb low pressure over Scandi

http://modeles.meteociel.fr/modeles/gfs/runs/2015011906/gfs-0-216.png?6

 

Whilst I believe a W,lys is likely, such a switch in 24hrs makes me want to view more runs before being certain.

[Alexis]

 

The huge standoff continues.

 

GFS = widespread snow

 

 

 

 

 

vs

 

UKMO: "snow confined to hills in the north" (direct quote)

 

 

 

http://www.bbc.co.uk/weather/

Added the very last link because it includes the latest Met Office thinking, based on the UKMO's output.

 

It's a brave person that bets against the Met Office fax charts and forecasts this close. Which will yield? I still think looking at the angle of frontal attack (see the fax chart) and the rising uppers that the Met Office are right, but it's a borderline event either way.

 

 

• one day two weeks ago the Met were forecasting 'cloudy and gloomy' for NW England at 12 hours. The next day saw clear skies and sunshine!

• the GFS charts were showing hatching over the whole of NW England on Saturday. It was mostly rain.

 

So neither is perfect!

[mulzy]

The medium term outlook is poor as far as sustained cold weather is concerned.

 

The 0z ECM ensembles for London show this albeit with considerable spread after day 9.

 

 

It looks like the positive NAO signal that has characterised this winter is likely strengthen as indicated in the GEFS.

 

 

So, a return to a zonal setup with cool PM/rPM air alternating with mild TM air is the form horse.  Not what most 'coldies' would want but hey-ho....

Edited January 19, 2015 by mulzy

[seaside 60]

Thought I would compare todays 06Z with yesterdays!

 

1035mb high over Scandi

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2015011806-0-240.png?6

 

Today a 975mb low pressure over Scandi

http://modeles.meteociel.fr/modeles/gfs/runs/2015011906/gfs-0-216.png?6

 

Whilst I believe a W,lys is likely, such a switch in 24hrs makes me want to view more runs before being certain.

Which is a prime example of why you shouldn't quote comments like all mild just because today's models show it today.

Does no one learn from previous model uncertainty, does no one read posts like Tamara's.

It's very certain that the next few days will show various outcomes.

[mushymanrob]

Pretty much how this cold spell started as well, while these charts are useful for a general theme they do not pick up features that can greatly;y effect our weather..... 

 

indeed the noaa anomaly charts didnt pick up on the length of the cold spell, but as a mean northwesterly, an occassional flow north of the mean is likely. its just the length that wasnt picked up on, but as john holmes says they are c70% accurate for predicting the mean flow for upto 14 days ahead. so as with any predictive chart, isnt perfect.

 

 

To be fair Mushy, i think he did say he agrees with the met solution.

 

 

yes i know, i should have highlighted the question he posted not the whole paragraph.

 

Hi Rob,

 

Yes I think they're right. For me it's all about the frontal angle. It's wrong for a widespread snow event off a north-westerly approaching low pressure system. That's my opinion, that's all, but you can see it on the fax chart output and the MetO's current forecasting.

 

This may be wrong, and fwiw I'm not even an amateur meteorologist (as Steve Murr is). I wish these model outputs looked different, but to me this week looks cold but mostly not-white.

 

best, Richard

 

im in agreement with you here

 

except that once i did experience significant snow off a slow moving front from the west/northwest... in 1969! lol.

[IDO]

Following on from the 0z run the 06z reinforces the westerly regime taking over again by D7. the GFS mean:

 

 

A couple of outlier solutions amongst the members. Looking at the MJO the repeating winter pattern of entering COD looks like resurfacing before we moved into a more interesting regime. So based on this winter we are likely to see a zonal flow with baby ridge/troughs. So brighter and wetter alternating periods in PM to TM flows. That looks like it will take us in to Feb based on current output. GFS op FI is again showing the return of the PV to its winter home:

 

MJO: 

 

The strat vortex over Siberia makes it a bit more interesting for Feb onwards with the GFS showing warming. However we have been here before and probably another seven days of runs before we know where that will take us.

 

As for the snow, the two fronts merging Tuesday into Wednesday may be interesting for some, however the SE may struggle for any frontal snow. The fronts on Friday look on this run to be rain south of the M62.

Edited January 19, 2015 by i'm dreaming of...

[The Weather Dragon]

The models have thus far handled this complex situation very well - and all have been signalling the return of W/SW regime for some time. We need a reset which takes us into February. More than likely looking towards mid February for another shot at cold.

Edited January 19, 2015 by Jonathan Evans

[winterof79]

The models have thus far handled this complex situation very well - and all have been signalling the return of W/SW regime for some time. We need a reset which takes us into February. More than likely looking towards mid February for another shot at cold.

The complex situation hasn't happened yet and they have been all over the place.The rest of the week looks cold with fronts at the end of the week looking to try and push in.

As for using the M62 as a snow line IDO,forget it.It's not like using the M4 as there are the pennines which run down through Derbyshire and South Yorkshire.