Model output discussion - 1st December onwards

[SMU]

^^^^ no model is ever any good with such a modality switch - we could go from an AO that peaked around + 4 to values to around -4 in a matter of 2 weeks which is rare as hens teeth -

just browsing the late runs - the 18z JMA which runs to 84 is a carbon copy of the UKMO & the GFS ensembles are swinging ( as usual ) around to the euros ....

I suspect we have another 3-5 GFS operationals before its on board -

 

 I was a little surprised by the muted excitement from the 12Z DET - it shows 3 big snow events for the UK with the north fairing the best, but the majority seeing snow at some point - its not exactly an everyday event widespread snow so we should take it with open arms-

Also with each passing run the amount the atlantic makes inroads into the scandi block is becoming less & less so at day 9 & 10 if we have a low trying to get across into the North sea - dont be surprised to see that correct westwards as well

 

All in all a great day with the euro scores up from 8/10 to 8.5/10 ...

UKMO takes the run of the day award .... 

S

 

Edited December 29, 2015 by THE CHOSEN ONE

[northwestsnow]

17 minutes ago, Glacier Point said:

And to add further to that, the previous update to the EC32 didn't have much of a mean -AO signal at all for week 2 and 3

[Man With Beard]

Steve - maybe some people were hoping to see the whole cold pool get to the UK. 

I wouldn't rule it out yet - what do you think?

 

[SMU]

23 minutes ago, Man With Beard said:

Steve - maybe some people were hoping to see the whole cold pool get to the UK. 

I wouldn't rule it out yet - what do you think?

 

Certainly still an option & well within the realms of possibility -

The slider low at 144 would ideally need more trough disruption & to seperate into 2 systems moving apart - this always allows the CAA over the top an easier pathway west...

is it out there yet?

look & PTB 6 & 10!!!!!!

look at PTB 10 @138 then UKMO 144

s

Edited December 29, 2015 by THE CHOSEN ONE

[Eskimo]

Indeed...quite a few perturbations which aren't too bad at all! 

[Eskimo]

For interest, and for accuracy. Here's what the ECM was predicting 7 days in advanced for the 29th on the 22nd.



Tomorrow (Actual)

 

I think that's pretty damn good 

[swilliam]

39 minutes ago, THE CHOSEN ONE said:

Certainly still an option & well within the realms of possibility -

The slider low at 144 would ideally need more trough disruption & to seperate into 2 systems moving apart - this always allows the CAA over the top an easier pathway west...

is it out there yet?

look & PTB 6 & 10!!!!!!

look at PTB 10 @138 then UKMO 144

s

Yes it depends what folks want. The Det gave a snow fest for many but never brought the real cold near us. The 2 perturbations S mentions get the cold pool in but do not deliver much snow (based on the current run - I know the oft touted saying here get the cold in the snow will come  - but this is not always true - e.g. Feb 86). In either event though it looks like the disrupted nature of the NH profile will allow opportunities further down the line.

Concerning means and other LRF models (beyond D10) I think generally they are not worth the paper they are written on in terms of the weather wee will experience in our little  locale. This especially true when the set up is volatile as now. People hanging on to the Meto 30 day outlook should really need to relax. This is only going to represent the largest cluster(s) and as the sum of these is probably less than 50% so is more likely to be wrong as right. If it says there is no sign or low probability of a prolonged cold spell then that is exactly the case - based on what is before them. However this does not mean a cold spell will not happen - just that it is not shown in the clusters.

 

Finally someone asked why was the forecast model output was not the same as the analogue composite shown for the forecast MJO state for previous occasions. If LRF was that simple we would not all be on this forum!

[Cheshire Freeze]

GFS with an apparent early shift towards the earlier euros at 96 hours. Less force on the block, better orientated blocking and LP disrupting better

 

Edited December 29, 2015 by CreweCold

[northwestsnow]

8 minutes ago, CreweCold said:

GFS with an apparent early shift towards the earlier euros at 96 hours. Less force on the block, better orientated blocking and LP disrupting better

 

Aye, soon goes wrong thereafter though.

And now its stuck, sheeeesh!!!! 

Very slow coming out but its not going to be a good run imho, over to ukmo which will hopefully keep the faith

Edited December 29, 2015 by northwestsnow

[Cheshire Freeze]

6 minutes ago, northwestsnow said:

Aye, soon goes wrong thereafter though.

Yes, rather than simply ejecting the following low SE it's more intent on bouncing it back off the block and off towards the NW. I'm not sure I'm buying that from the GFS.....it played that trick with the first LP which now miraculously disrupts at 96 hours.

Edited December 29, 2015 by CreweCold

[northwestsnow]

UKMO keeps the faith with the slider at 144

No idea of 850's etc but looks good to me with a wedge of high pressure in the GIN forcing the jet SE.

 

Edited December 29, 2015 by northwestsnow

[Cheshire Freeze]

7 minutes ago, northwestsnow said:

UKMO keeps the faith with the slider at 144

Yes but not as good as the 12z and I don't think it's cold enough at 144 to support snow. It also looks like any blocking is losing control. Outputs are a mess at the minute and I wouldn't like to be making a forecast right now. Anything from heavy snow to flooding rain looks possible.

EDIT: GFS trying to pull it out the bag at day 8...building heights West towards Greenland too

If we can get any retrogression of that HP, we've won the lottery.

Edited December 29, 2015 by CreweCold

[Mucka]

I'm happy with the output so far.

GFS doesn't get there but it is another step toward the Euros and UKMO maintains the undercut albeit we could do with that low disrupting more and getting some cold uppers across us.

 

[northwestsnow]

2 minutes ago, Mucka said:

I'm happy with the output so far.

GFS doesn't get there but it is another step toward the Euros and UKMO maintains the undercut albeit we could do with that low disrupting more and getting some cold uppers across us.

 

Next slide would be good on UKMO

Put it this way, i'm getting giddy  in my location, and the hills up the road are 297 m ASL- in the zone!!!!

Edited December 29, 2015 by northwestsnow

[Mucka]

Just now, northwestsnow said:

Next slide would be good on UKMO

Oh it's a good chart alright and as the low slides SE we would draw colder in, I'm just looking for better margins. 

[northwestsnow]

5 minutes ago, Mucka said:

I'm happy with the output so far.

GFS doesn't get there but it is another step toward the Euros and UKMO maintains the undercut albeit we could do with that low disrupting more and getting some cold uppers across us.

 

Gfs shouts cold zonality to me mucka and is a big improvement on 18z.

[Mucka]

2 minutes ago, northwestsnow said:

Gfs shouts cold zonality to me mucka and is a big improvement on 18z.

Yup trending the right way and good to see that although it doesn't get the undercut the Euros do it maintains the block to the NE which would allow further opportunities.

 

[northwestsnow]

Just now, Mucka said:

Yup trending the right way and good to see that although it doesn't get the undercut the Euros do it maintains the block to the NE which would allow further opportunities.

 

You can call at mine for a cuppa in a week or so time and watch the snow falling  

Joking aside its knife edge stuff, hopefully ecm keeps the faith but even with gfs i would imagine there is scope for some snow across northern Britain. Obviously with cold zonality elevation will help but too far away for specifics at the mo.

 

[Cheshire Freeze]

Interestingly, or maybe worryingly, both GFS and GEM go for a storm around 220 hrs out

 

[Lakigigar]

 

Lots of rain for belgium in this run. According to this run, it will be a thriller, but the autumn will still win, with many rain (and maybe some snow for me).

[Lakigigar]

 

I think it is best to not look to far. 144h charts show the differences between the models are huge. Details such like how cold pools wil react, how the russian anticyclone will behave, how the ocean wil behave, what the UK low will do, what the shape of the MS (meditarrean sea) will look like aren't that predictable

[legritter]

Just  a very quick one from me ,very exciting charts at the moment ,and if current 120hr fax chart was being shown 30 yrs ago i would be over the moon .

lets hope today can deliver chart wise cheers all .

[SMU]

Morning -

lots of people looking down the line st days 7/8 for cold & snow when some could be on our doorstep day 3 & 4 with the ECM continuing to upgrade to cold as we approach real time

T72 sees a cold westerly flow introducing pretty cold uppers for thr north - circa -5c with a pool of -7c air over scotland -

This cold pool is important because just a day later we have an atlantic low sliding into that - with the miler air not penetrating that far North -

 

That gives me confidence that a band of snow for Scotland & the North could give accumulations as early as Saturday early hours.......

EDIT : day 5 ECM continues to hold any atlantic mixed air away from the borders - so for this uocoming cold spell scotland & the far NE could stay very cold throughout.....

 

s

Edited December 29, 2015 by THE CHOSEN ONE

[Liam J]

Out to T168 and the only real cold hit's Shetland on this run bar a westerly shot at day 3 with -6c 850's over Scotland from the west. 

 

[Man With Beard]

ECM T144 - the cold pool has hit a disturbance over Norway which stops a clean westward progression. Result - at T168 the Atlantic low has not linked very cleanly with the cold pool as it is too far away - it slides less, and the polar front ends up further north.

Not a disaster but a small movement away from a cold snap, certainly for midland areas. Bear in mind we're still talking about a T144 chart which is ages away in such a set up. And, there's still an area of heights to our north at T168 which could result in something further along the line.