Model Output Discussion:

[Lewis]

My fav charts of this mornings run;

Thickness:

Clearly shows the convective energy coming off the N Sea;

Wind:

[bluearmy]

i just realised i've been mixing up my rex's with my omega's on all my posts over the past fortnight. (should have concentrated harder all those years ago). this omega block has been showing on the extended ens mean for ages - why the atmosphere now seems more predisposed to allow it to happen, we'll never know although some will have a good go.

anyway, looks like steve m has picked the right 10 day period to go snow chasing. looking at the 06z ens, he can start at home next wed and work his way up country. i reckon 2 or 3 decent frontal snow events between next tues and the following 10 days somewhere over the UK.

[*Stormforce~beka*]

At last! We can sit back and take a breath beofe disecting the models in fine detail. Pretty much nailed on that the next 7-10 days won't be Atlantic dominated.

I would say nothing is nail on until at least early Saturday!! Not worth putting sentences out like that when the models have been absolutely mad and swapping like mad lately.

[Bottesford]

Several off topic or one line comments have been removed. Please keep on topic and post with 'substance'. One line comments like '12z is great' isn't really adding anything to the discussion.

Thanks.

[Blizzard_of_Oz]

i'm with you on the lack of confidence. i think if the 12z's continue with the theme we can start to relax. as for snow, well if all goes to plan then it will be the snowiest spell this winter for many in the east. even typing that makes me feel i'm jinxing things!!

I'm quitetly beginning to gain some confidece now that the runs are in some agreement, could any 1 with more knowledge PLEASE explain what sort of temperatures we could expect by Monday and Tuesday according to the latest runs. Like some 1 mentioned earlier lets get the cold first then the Snow potential if any.

Will this be the extremely cold Easterly that was mentioned a while ago or a weakened Easterly some members have been posting charts showing -15 is that possible in my part of the country East Hertfordshire? Your thoughts please on the model runs at present in terms of temperatures from the ensembles or should I wait for the answer after the next 2 runs, I hate to say this but after last weeks fiasco on the model runs Im still a little cautious but I understand that all of the models are showing some dgree of cold beginning next week. Thankyou.

[Bobby]

Nice to see the cold trend continued today, however

Looking at the ensembles shows the consierable uncertainty still, I think a lot of it depends on what happens to the short waves heading for us coming off the Atlantic, I suppose there are 3 main evolutions possible and it's a very fine line to either one.

Possibility #1 is similar to the OP GFS with the Atlantic held well at bay allowing a very cold but slackish NEly feed quickly into Britain with shortwaves weak and well to our south.

http://91.121.94.83/modeles/gfs/run/gfs-0-168.png?6

Possibility #2 is the worst case scenario with the Atlantic strongly pushing in and instead of undercutting goes right over us, stopping us getting any cold (apart from Scotland)

http://91.121.94.83/modeles/gens/run/gens-9-1-168.png?6

Posesibillity #3 is similar to #2 but things are further south with a big undercut and a channel low set up, setting up a major 78 style blizzard potential for south Britain, potent easterly following. GEM and NOGAPS show this set up, dangerous but potentially spectacular

http://91.121.94.83/modeles/gens/run/gens-19-1-168.png?6

[Frosty.]

The GFS 06z is another snowfest run for all of eastern britain but there would also be some snow in other areas too, widespread sub-zero temps, I actually thought the gfs 00z was better but I would take this run. The ecm 00z was a very dry run due to the failure of the scandi trough to impact on the uk so that is something to bear in mind, we look as though we will be guaranteed cold next week..but will it snow :lol:

[Buzzit]

To me the following frames some up the situation (which if you love snow how could you ask for more ?)

[Cecil Hogmanay Melchett]

Excellent models this morning.

If i were in the East/South East id be very excited. :lol:

Ens show the op has good support.With ssts looking cold to the east i dont think modification will be much

of an issue this time round although i know its to early to say where it will snow.Kudos to those who kept the faith i raised the white flag more times than soft mick.

[Bobby]

Big scatter which starts on 7-8 Feb on the ensembles shows uncertainty still. FI is 7-8 Feb (T+72 - T+96), little point looking beyond that. Same on ECM ensembles too.

[Guest North Sea Snow Convection]

Nice to see the cold trend continued today, however

Looking at the ensembles shows the consierable uncertainty still, I think a lot of it depends on what happens to the short waves heading for us coming off the Atlantic, I suppose there are 3 main evolutions possible and it's a very fine line to either one.

Possibility #1 is similar to the OP GFS with the Atlantic held well at bay allowing a very cold but slackish NEly feed quickly into Britain with shortwaves weak and well to our south.

http://91.121.94.83/...gfs-0-168.png?6

Possibility #2 is the worst case scenario with the Atlantic strongly pushing in and instead of undercutting goes right over us, stopping us getting any cold (apart from Scotland)

http://91.121.94.83/...s-9-1-168.png?6

Posesibillity #3 is similar to #2 but things are further south with a big undercut and a channel low set up, setting up a major 78 style blizzard potential for south Britain, potent easterly following. GEM and NOGAPS show this set up, dangerous but potentially spectacular

http://91.121.94.83/...-19-1-168.png?6

We do need further outputs to be totally sure but I would suggest that the second possibility has reduced considerably over the last 24 hrs.

A combination of 1 and 3 is one I would have a stab at without neccessarily involving a huge blizzard as such. It looks to me as if atlantic shortwave energy is being steadily down sized by the models although this doesn't preclude some snow potential at all - for the south west in particular.

But again, we need to stay away from discussing details atm for any part of the UK

Edited February 4, 2010 by North Sea Snow Convection

[nick sussex]

Nice to see the cold trend continued today, however

Looking at the ensembles shows the consierable uncertainty still, I think a lot of it depends on what happens to the short waves heading for us coming off the Atlantic, I suppose there are 3 main evolutions possible and it's a very fine line to either one.

Possibility #1 is similar to the OP GFS with the Atlantic held well at bay allowing a very cold but slackish NEly feed quickly into Britain with shortwaves weak and well to our south.

http://91.121.94.83/modeles/gfs/run/gfs-0-168.png?6

Possibility #2 is the worst case scenario with the Atlantic strongly pushing in and instead of undercutting goes right over us, stopping us getting any cold (apart from Scotland)

http://91.121.94.83/modeles/gens/run/gens-9-1-168.png?6

Posesibillity #3 is similar to #2 but things are further south with a big undercut and a channel low set up, setting up a major 78 style blizzard potential for south Britain, potent easterly following. GEM and NOGAPS show this set up, dangerous but potentially spectacular

http://91.121.94.83/modeles/gens/run/gens-19-1-168.png?6

A good post and shows why we're not over the finish line yet. Generally in these circumstances the operational run takes precedence as its higher resolution is better able to track shortwaves, you often find with this type of evolution the ensembles will remain scattered quite close in because of this.

Of course I'd much rather see complete support for the cold pattern but for the moment I wouldn't be too concerned of those more average looking ensembles.In terms of the no gaps and gme today I suspect the reason they show their respective outcomes is their operationals aren't run at the higher resolutions of the ECM/GFS and UKMO and therefore because of the need to map the shortwaves very accurately they are more prone to error.

If you take a look at todays NAE 06hrs run which is run at higher resolutions than even the main models that looks fine, even though it only goes upto 48hrs it still looks like clearing the shortwave se without any residual energy left behind.

Edited February 4, 2010 by nick sussex

[Archie_Lewis]

Big scatter which starts on 7-8 Feb on the ensembles shows uncertainty still. FI is 7-8 Feb (T+72 - T+96), little point looking beyond that. Same on ECM ensembles too.

Too true..... To much scatter if you ask me.

Things could still go very wrong. Alot of caution needed up until Saturday afternoon at the very earliest

Once again Members getting far to carried away far to early..........

[Lewis]

Can i ask a question..

Have the following models, GFS, GEM, UKMO, ECM, JMA all shown the (or) the potential for this East/NE'rly?

Thanks in advance

Edited February 4, 2010 by Storm Force Lewis

[Thunder Snow]

It's really remarkable how the models can change so quickly.

[Frosty.]

An increasingly wintry meto update today which combined with the very cold 00z's & 06z should reinforce the trend to yet another potent cold spell as long as scandi shortwaves behave themselves. :lol:

[bluearmy]

thats not scatter archie. the cold is clumped with the minority balance scattered. unlike the past three weeks nwp, i have no doubt that parts of the UK will have very cold conditions next week with snow. (that gives me a 600 mile 'get out', though i doubt i'll need it).

the ecm ens temps for london are similar with scatter in the less cold runs.

Can i ask a question..

Have the following models, GFS, GEM, UKMO, ECM, JMA all shown the (or) the potential for this East/NE'rly?

Thanks in advance

yes Lewis, JMA showed the general trend two days ago but was less attractive yesterday. GEM showed a supressed undercutting trough yesterday though its op is further north today. we will see from their 12z's if they are back 'on message'.

[MAF]

so how far out are you guys placing FI?? seems to me that not much has changed in the "uncertainty" stakes.

(there are still a lot of people saying "wait until the weekend to verify" )

yet FI is been talked about as been a lot further out than it was a few days ago :lol:

[Lewis]

thats not scatter archie. the cold is clumped with the minority balance scattered. unlike the past three weeks nwp, i have no doubt that parts of the UK will have very cold conditions next week with snow. (that gives me a 600 mile 'get out', though i doubt i'll need it).

the ecm ens temps for london are similar with scatter in the less cold runs.

yes Lewis, JMA showed the general trend two days ago but was less attractive yesterday. GEM showed a supressed undercutting trough yesterday though its op is further north today. we will see from their 12z's if they are back 'on message'.

Thanks mate,

So it's safe to say, with such model agreement across the board, obviously your always going to get milder/warmer members, that we are more or less 70/30 favoured for a very cold start to next week. Just a lot of people are saying the models change so quickly etc and not too get excited, i agree thats the best way of looking at it, forget snow, get the cold and pattern/trend first, certainly looks like we have that.

After all, the other week before it all went pear shaped some of the models (not all) was showing an east/north easterly. It dissapeared and now its back on all models, and what a coinsidence, it vanished and it appeared on the same date! :lol:

Mouth watering outputs.

[Guest North Sea Snow Convection]

An increasingly wintry meto update today which combined with the very cold 00z's & 06z should reinforce the trend to yet another potent cold spell as long as scandi shortwaves behave themselves.

An excellent update which is a good boost to confidence in this mornings modelling and rules out that no 2 possibility.

We do still need another round of model suites to be properly sure - but, touch wood, things will stay steady now and by the weekend people can start looking at details.

I would suggest that if we get to tonight with all models pointing in the same direction, then it is safe to say there WILL be an easterly, and it will be a case of how cold and how long lasting it is, as well as how much snow. We need that first of all though - until then best to be cautious with anything past Monday.

Have a good afternoon all

Edited February 4, 2010 by North Sea Snow Convection

[TEITS]

For me the best charts this morning are actually at +48/+72.

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2010/02/04/basis06/ukuk/pslv/10020606_0406.gif

http://www.wetterzentrale.de/pics/Rtavn721.png

The next stage that we need to focus on is +96/+120.

http://www.wetterzentrale.de/pics/Rtavn1201.png

Will the cold pool back SW as suggested by the GFS. The GEFS mean says yes.

http://91.121.94.83/modeles/gens/run/gens-21-1-120.png?6

The ensembles for Cambs are excellent with the mean near -10C. If the current trend from the GFS continues that mean could drop to around -12C.

http://cirrus.netweather.tv/ensimages/ens.20100204/06/t850Cambridgeshire.png

Finally I would like to explain why I focus on E Anglia/E midlands/Lincs. The simple reason is due to living in this area for my entire life. I have a good understanding of what different weather patterns bring to this area. I cannot comment for locations such as E Scotland, NE England because I have no experiences of this area.

[nick sussex]

If anyones bored and wants a very interesting read heres an excellent link about how the models work, the most interesting part is headed inherent model errors.

http://www.hpc.ncep.noaa.gov/mdd/

Yes I know I should get out more! :lol:

[Damp and dreary]

Big scatter which starts on 7-8 Feb on the ensembles shows uncertainty still. FI is 7-8 Feb (T+72 - T+96), little point looking beyond that. Same on ECM ensembles too.

The scattering always starts within 3 or 4 days, if you look at your posted chart you will see many more go for the colder option than warmer. Still as always harder to be correct after that but deffinately swinging the right way....

[Lewis]

"Finally I would like to explain why I focus on E Anglia/E midlands/Lincs. The simple reason is due to living in this area for my entire life. I have a good understanding of what different weather patterns bring to this area. I cannot comment for locations such as E Scotland, NE England because I have no experiences of this area."

Hi,

With you seeing yourself as more advanced than others with regards the model outputs, you should get a clear idea just from the charts (experience does not come down too it with regards your own area) it does when it's nowcasting, and your in the time frame.

I'm experienced with my area, 9 times out of 10 i'm normally spot on with regards forecasting, Reef is the same. You also have to remember the past 3-4 east/north easterly's have not really delivered for your area, with NE england and Scotland, N yorkshire getting a pasting.

[Lewis]

Here you go......

UK Outlook for Tuesday 9 Feb 2010 to Thursday 18 Feb 2010:

Rather cold with a mixture of bright spells and scattered sleet and snow showers in the north and east. Strong winds are also expected around exposed eastern coasts. The driest and brightest weather is expected in the northwest for much of the period. Rain, sleet and snow may spread into the south during Thursday, clearing southwards by the weekend (12th-13th). Overnight, frost is likely in many places, with locally severe frost inland. Remaining cold for the rest of the period with snow showers, particularly in eastern and some central areas, with perhaps some significant accumulations of snow in places. There is also a risk of further bands of rain, sleet and snow spreading into the south, particularly later in the period.

Updated: 1155 on Thu 4 Feb 2010

Thanks very much for that, looking very promising, has anyone noticed that the metoffice tend to always give more information in FI than short range, or is it just me lol?