Model Output Discussion - 26th December - 1st January

[Gibby]

GFS continues to show a very changeable Atlantic based pattern between azores High pressure out to the SW and Low pressure crossing East to the North of Britain. Wet and windy spells mixed with colder showery spells look likely with some snow on Northern hills at times through next week. In FI High pressure takes hold with dry, quiet weather taking hold with night time ffrosts and fog under any clear skies especially in the South. The ensembles show the operational was once more a massive mild outlier at the end with the majority of members keeping close or just below the long term mean for London. UKMO also keeps the familiar synoptic setup that we've become accustomed to with Tuesday looking a potentially stormy day mixed in with the alternating mild and cooler days. ECM also brings a vigorous storm system across the UK on Tuesday with a temporary colder interlude for the UK on its exit away east.

It looks still an Atlantic based setup from the models tonight revolving entirely around the behaviour of the Azores high pressure. Mild and wet and cool and showery remain the likely mix over the coming week or two with some runs showing the High pressure coming in closer to the UK enhancing the warm sectors on the polar front at times in the vicinity of the UK. Others keep the High slightly further away maintaining a cooler zonal spell of weather going in the latter stages of tonights output

[kev238]

Up to about day 10 it is more of the same. Mild zonal interspersed with cooler zonal periods. Due to a lack of frosty nights, temperatures overall will be above average although it will feel cool in strong winds.

There is potentially a stormy spell of weather on Tuesday, though precise locations of the worst areas to be hit are open to debate at the moment.

After day 10, then perhaps a small change, more settled perhaps... However it does seem we are a long, long way from anything approaching even a sniff of lowland snow in England and wales.

[sub zero]

Maybe with the operational not playing ball for us coldies ,its time to take a look at the control run. This shows the main pv slowly on its way to Scandinavia , leaving us in a nw flow.. along the lines of Gps forcast ( I believe). It also finishes with an arctic high of 1050..

[bluearmy]

time for a reality check for those of you thinking the gfs op is being unreasonable to throw out the fi solutions it currently is?

it occurred to me that the new parallel gefs is at a high resolution beyond T192 wrt the op. so i thought i wonder if the control gefs 12z will look like the op 12z today at T192

gfs on the left and gefs control on the right

very similar

lets look at them now at T384 with them running at a fairly similar resolution

gfs on the left and gefs control on the right

does the op look like an outlier now ??? i suspect the lower res of the normal gefs ensembles are letting them down post T192. as JH has indicated courtesy of the 500mb charts etc, not much likely to change before mid month in our part of the NH.

Edited December 30, 2011 by bluearmy

[TEITS]

i suspect the lower res of the normal gefs ensembles are letting them down post T192.

That in my opinion is exactly what it is. I've lost count how many times i've seen the GFS Ops continously being outliers and yet proved correct as the ensembles slowly agree.

[Frosty.]

An unusual event on the way early next week from the Ecm 12z especially, 2 coldish days in a row..something to celebrate

As we all know, the winter so far has lacked frost and snow, a few areas have seen neither of both but there is a chance of heavy snow next tuesday with high winds in some northern areas (mainly at elevation) which may even get a meto warning by sun/mon. Still a lot of mild and average weather to come but also some short colder incursions but the biggest feature next week will be the strong winds. I remain hopeful that the moderate strat warming will gradually feed into the model data and slow down the raging jet and maybe build a strong mid atlantic ridge at some point.

[jpwild]

An unusual event on the way early next week from the Ecm 12z especially, 2 coldish days in a row..something to celebrate

As we all know, the winter so far has lacked frost and snow, a few areas have seen neither of both but there is a chance of heavy snow next tuesday with high winds in some northern areas (mainly at elevation) which may even get a meto warning by sun/mon. Still a lot of mild and average weather to come but also some short colder incursions but the biggest feature next week will be the strong winds. I remain hopeful that the moderate strat warming will gradually feed into the model data and slow down the raging jet and maybe build a strong mid atlantic ridge at some point.

This is a problem I have with the model thread is the vaguness of locations.

'northern'? Seriously, when people say that or 'southern' well, I feel it's very vague and not intelligent. Why don't you or others be a bit more specific?

Possible snow for northern areas? Is that in parts of Scotland, Newcastle, Preston, Leeds, Manchester?

Also, what elevation? Again people say elevation, but not many say what elevation.

May as well say 'well, next week there will be weather'.

Edited December 30, 2011 by jpwild

[Frosty.]

This is a problem I have with the model thread is the vaguness of locations.

'northern'? Seriously, when people say that or 'southern' well, I feel it's very vague and not intelligent. Why don't you or others be a bit more specific?

Possible snow for northern areas? Is that in parts of Scotland, Newcastle, Preston, Leeds, Manchester?

Also, what elevation? Again people say elevation, but not many say what elevation.

May as well say 'well, next week there will be weather'.

Well it's hard to be specific at this range, even the experts wouldn't know the answer to that until a few days before but I would say cold with wintry showers on monday and scotland for the snow next tuesday above 800 feet but this is only my opinion, sorry if my vagueness has irritated you.

Edited December 30, 2011 by Polar_ Low

[J10]

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gfs&MODELLTYP=1&BASE=-&VAR=prec&HH=192&INFO=1&ARCHIV=0&ZOOM=0

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=prec&HH=6&INFO=1&ARCHIV=0&ZOOM=0

According to above,

resolution of GFS is 0.5 degrees to T+180, 2.5 degrees thereafter.

resolution of GEFS is 1.0 degrees throughout

So this would indicate the ensembles being at a higher resolution than the operational GFS past T+180.

If someone could confirm this I would be grateful.

[shotski]

This is a problem I have with the model thread is the vaguness of locations.

'northern'? Seriously, when people say that or 'southern' well, I feel it's very vague and not intelligent. Why don't you or others be a bit more specific?

Possible snow for northern areas? Is that in parts of Scotland, Newcastle, Preston, Leeds, Manchester?

Also, what elevation? Again people say elevation, but not many say what elevation.

May as well say 'well, next week there will be weather'.

To be fair, if polar low could give an exact location for any would be snow next Tuesday he would be working for the met office.

[Buzz]

This is a problem I have with the model thread is the vaguness of locations.

'northern'? Seriously, when people say that or 'southern' well, I feel it's very vague and not intelligent. Why don't you or others be a bit more specific?

Possible snow for northern areas? Is that in parts of Scotland, Newcastle, Preston, Leeds, Manchester?

Also, what elevation? Again people say elevation, but not many say what elevation.

May as well say 'well, next week there will be weather'.

Given that the track of the depression won't be nailed on for some time yet, how can you expect anyone to specify where there will be snow?

Forecasting snow is not a precise art with this kind of setup, so patience is required.

Meanwhile, this is the model discussion thread, not the "where exactly will it snow" thread.

[Frosty.]

To be fair, if polar low could give an exact location for any would be snow next Tuesday he would be working for the met office.

It's impossible for me to post something that everyone will agree on or like but i'm doing my best with my limited knowledge, it's been a bad day at the office for me today though, and thanks for your comment. As for the models, definately a colder start to next week with some wintry showers and then a risk of disruptive weather on tuesday.

[A Winter's Tale]

This is a problem I have with the model thread is the vaguness of locations.

'northern'? Seriously, when people say that or 'southern' well, I feel it's very vague and not intelligent. Why don't you or others be a bit more specific?

Possible snow for northern areas? Is that in parts of Scotland, Newcastle, Preston, Leeds, Manchester?

Also, what elevation? Again people say elevation, but not many say what elevation.

May as well say 'well, next week there will be weather'.

Ask Victoria Wood!

I think that it's meant be anywhere north of Cumbria and Northumberland. Anyway, these incursions probably won't be quite as good as that earlier this month as they lack the puch of those incursions in past few weeks. So no real lying snow, and nothing for anywhere in east or the south. Still, it could end up being that Western Scotland continues it's wintry winter. It delivered us a good December for snow and it may add up our snow totals for January but as far as I'm concerned these incursions in December has ticked the box of "Yes, this Winter won't be a repeat of the likes of 06/07 and continue the theme of consecutive winter with a decent number of snowfalls and decent snow events", but other than getting a good tally for January, with that box ticked back in December, the interest now is for a great cold spell or snowfall that affects most of the UK, not just the Victoria Wood North.

[lorenzo]

time for a reality check for those of you thinking the gfs op is being unreasonable to throw out the fi solutions it currently is?

it occurred to me that the new parallel gefs is at a high resolution beyond T192 wrt the op. so i thought i wonder if the control gefs 12z will look like the op 12z today at T192

gfs on the left and gefs control on the right

very similar

lets look at them now at T384 with them running at a fairly similar resolution

gfs on the left and gefs control on the right

does the op look like an outlier now ??? i suspect the lower res of the normal gefs ensembles are letting them down post T192. as JH has indicated courtesy of the 500mb charts etc, not much likely to change before mid month in our part of the NH.

Good analysis BlueArmy, I recall you also updated us on the resolution changes due in February this week, this IMO is worthy of a thread of it's own, it would be a great reference point as to where the model accuracy has cut off points.

If for anything it would assist in determining where FI begins within each model.

[jpwild]

Given that the track of the depression won't be nailed on for some time yet, how can you expect anyone to specify where there will be snow?

Forecasting snow is not a precise art with this kind of setup, so patience is required.

Meanwhile, this is the model discussion thread, not the "where exactly will it snow" thread.

What's the point in forecasting weather without knowing the locations that it will affect?

[Summer Sun]

Been looking at the snow risk for next week and 2012 looks like starting rather snowy for parts of Scotland

Start's off with not much

But is soon develops 6hrs later

And 6hrs later

Another 6hrs passes with the North west getting all the snow still

By 18:00 the central belt see's the snow

By Midnight it has all cleared with those of us in England having nothing but rain if your lucky whilst north west scotland turns very white, as for snow on Tuesday there is nothing to get excited about yet this is the best it get's

Most of it is shown to fall as sleet still time for change yet of course but don't get your hopes up to much unless you live in North West Scotland of course.

Edited December 30, 2011 by Gavin D

[johnholmes]

time for a reality check for those of you thinking the gfs op is being unreasonable to throw out the fi solutions it currently is?

it occurred to me that the new parallel gefs is at a high resolution beyond T192 wrt the op. so i thought i wonder if the control gefs 12z will look like the op 12z today at T192

gfs on the left and gefs control on the right

very similar

lets look at them now at T384 with them running at a fairly similar resolution

gfs on the left and gefs control on the right

does the op look like an outlier now ??? i suspect the lower res of the normal gefs ensembles are letting them down post T192. as JH has indicated courtesy of the 500mb charts etc, not much likely to change before mid month in our part of the NH.

I think your explanation ba is as near to the actual as we can get from our amateur view of outputs unless anyone has more detailed info they can share?

Edited December 30, 2011 by johnholmes

[Tim Bland]

Interesting update from Mark Vogan about his take on the northern hemisphere weather pattern over the next few weeks.

No offence to Mark but he posted repeated videos in early December calling for -20c and widespread snow starting the 15th Dec.?!?!

[Thundery wintry showers]

No widespread cold/snow for the foreseeable future but, coming back to the model outputs after a holiday, it looks like there's plenty of "weather" on offer during the coming week. Tomorrow will be mild, cloudy and damp for most of us, then by New Year's Day we will be seeing a showery south-westerly covering most of the UK, and this regime will continue on the 2nd. With 850hPa temperatures falling to around -5C and low 500mb heights we should see snow showers become quite widespread on northern hills with some sleet and hail in the heavier showers at low levels, and also on southern hills. As is often the case with these showery westerlies, though, some eastern parts will miss out on the showers and stay dry and sunny.

The 3rd looks set to have quite a vicious storm with more gales likely across Scotland- not necessarily anything out of the ordinary, but worth keeping an eye on. After that, another couple of showery days with temperatures near average and more wintriness in the north.

There are certainly hints of a more anticyclonic outlook into FI but nothing in the reliable timeframe. The GFS 12Z FI has cold continental air nearby but the issue remains the absence of northern blocking which would prevent it from heading over to Britain.

[johnholmes]

This is a problem I have with the model thread is the vaguness of locations.

'northern'? Seriously, when people say that or 'southern' well, I feel it's very vague and not intelligent. Why don't you or others be a bit more specific?

Possible snow for northern areas? Is that in parts of Scotland, Newcastle, Preston, Leeds, Manchester?

Also, what elevation? Again people say elevation, but not many say what elevation.

May as well say 'well, next week there will be weather'.

I think you are really asking for too much there, if you have access to Net Wx Extra then you can do some of the detective work for yourself-and its fun doing it. Add in the information in the various guides and you will soon be able to give us your own view. Perhaps with the detail that you want others to do.

Not a dig at you just a suggestion to have a go yourself-then ask questions politely and someone will answer you as well as they are able.

[jpwild]

I think you are really asking for too much there, if you have access to Net Wx Extra then you can do some of the detective work for yourself-and its fun doing it. Add in the information in the various guides and you will soon be able to give us your own view. Perhaps with the detail that you want others to do.

Not a dig at you just a suggestion to have a go yourself-then ask questions politely and someone will answer you as well as they are able.

I'm not the one coming on here and attempting to predict weather by saying there could be snow in the 'north'. If people want to predict weather then brilliant, but what's the point when it's so vague? Doesn't help anything or anyone.

If I can't predict what the weather will be from the charts then I will say so and not say things like perhaps some snow in the north and not in the south. That's just pathetic vague.

[johnholmes]

I'm not the one coming on here and attempting to predict weather by saying there could be snow in the 'north'. If people want to predict weather then brilliant, but what's the point when it's so vague? Doesn't help anything or anyone.

If I can't predict what the weather will be from the charts then I will say so and not say things like perhaps some snow in the north and not in the south. That's just pathetic vague.

again perhaps you are expecting too much from this forum.

May I ask how much do you understand the models, synoptic, and others?

[Cecil Hogmanay Melchett]

Well as I suspected the ECM hinting at something more anticyclonic as we head towards midmonth,where the anticyclone will sit exactly is still subject to change but at least we should see temps dropping away at night bringing some chances of frost.

I stand by my thoughts from a few days ago that mid latitude blocking is the best we can expect in the reliable timeframe but thats a start,if the jet/Atlantic play ball then we could see some posibilty of retrogression in the long term(second half of Jan)but thats just a hope at the moment,nothing in the upstream to suggest its likely,yet!!

[bluearmy]

http://www.weatheron...ARCHIV=0&ZOOM=0

http://www.weatheron...ARCHIV=0&ZOOM=0

According to above,

resolution of GFS is 0.5 degrees to T+180, 2.5 degrees thereafter.

resolution of GEFS is 1.0 degrees throughout

So this would indicate the ensembles being at a higher resolution than the operational GFS past T+180.

If someone could confirm this I would be grateful.

from NOAA

GEFS

At NCEP the current NCEP Global Ensemble configuration consists of runs at

00Z, 06Z, 12Z 18Z each day (available through anonymous ftp from public servers)

Three different types of forecast files are generated from each run:

A T382L64 high resolution control (file name for, e.g., a 24 hr fcst at 00Z is gfs.t00z.pgrbf24) out to 7 days, after which this run gets truncated and is run out to 16 days at a T126L64 resolution

A T190L28 control that is started with a truncated T382L64 analysis and run out to 16 days,

20 perturbed forecasts each run out to 16 days at T190L28 horizontal and vertical resolution.

NEW GEFS (parallel)

Increases the horizontal resolution from T190 (about 70km) to T254 (about 50-55km) for the first 192 hours (8days) of model integration

Increased vertical resolution from 28 levels to 42 levels for 0-384 hours (0-16 days) forecasts

GFS OP

T574 /27 KM/ out to T192, thereafter T190 at 64 layers

you work it out!! i reckon it means that the op and ens control are currently the same horizontal resolution beyond T192. however, it talks about control and high res control. Help!!

Edited December 30, 2011 by bluearmy

[johnholmes]

from NOAA

At

NCEP

the current NCEP Global Ensemble configuration consists of runs at

00Z, 06Z, 12Z 18Z each day (available through anonymous ftp from public servers)

Three different types of forecast files are generated from each run:

A T382L64 high resolution control (file name for, e.g., a 24 hr fcst at 00Z is

gfs

.t00z.pgrbf24

) out to 7 days, after which this run gets truncated and is run out to 16 days at a T126L64 resolution

A T190L28 control that is started with a truncated T382L64 analysis and run out to 16 days,

20 perturbed forecasts each run out to 16 days at T190L28 horizontal and vertical resolution.

new gefs (parallel)

Increases the horizontal resolution from T190 (about 70km) to T254 (about 50-55km) for the first 192 hours (8days) of model integration

3. Increased vertical resolution from 28 levels to 42 levels for 0-384 hours (0-16 days) forecasts

GFS op

T574 /27 KM/ out to T192, thereafter T190 at 64 layers

you work it out!! i reckon it means that the op and ens control are currently the same horizontal resolution beyond T192. however, it talks about control and high res control. Help!!

send them an e mail they are sometimes quite good at replying although at other times it seems to get lost in their in mail box?