Model Output Discussion 29th December - Into mid-Winter.

[Ice Day]

18 minutes ago, Jason M said:

Don't get the whole 18z is rubbish argument. If peeps think that, why not stay away until the morning runs?

 

I think you'll find that certain 'characters' on here believe that it's only rubbish when it's showing cold!  

Anyway, there's a plethora of options on the table and the models are still struggling to reach an agreement of the way forward beyond 144 (or earlier actually). The output for the last 3 weeks has been truly incredible.  There's a 2/3 day period when mild options are in the ascendancy then momentum switches to colder solutions. The runs are showing the oddest solutions at the moment so it does have a feeling that something 'interesting' is just around the corner.  No doubt, we'll all be back here breakfast time in the morning.

Edited January 15, 2017 by Ice Day

[Nouska]

1 hour ago, Jonan92 said:

What a strange map, I have never seen such a thing

It's good to have a look at what NOAA see as Z500 upstream analogues in a situation like this. Images based on current 18Z GFS.

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/model_guidance.php?dayin=8

Day 8 Day 11

There are some years with low February CET and some not - there are a variety of paths this can take and if a SSW materialises who knows.

[The PIT]

GFS is basically showing the ecm solution from earlier. A bit accelerated that's all.  It's better as theres colder uppers. However its FI and if you think day ten or whatever are set in concrete prepared to be disappointed.

Despite model improvements and they are a lot better and we are probably getting to the point of diminishing returns I still haven't seen any reason to move from T96 as a reliable time frame.

[Eskimo]

2 hours ago, Steve Murr said:

Cant keep away-its like pandoras box

fantastic 18z from t96, max 1c for England as well-

Also 144 onwards the atlantic is going ESE not ENE- superb...

Haha I was just randomly thinking to myself when I ventured in here earlier after seeing the 18z run..."I wonder if Steve is twitching to come back on" and lo and behold, here he is!  Wouldn't be the first time either.... 

This is 'only' nine days away, could be 16 days away. Nothing will go wrong...nothing at all. 

[Iceberg]

What I am seeing in the models are:

the stratospheric winter vortex dying when we are still in jan(just). 

The tropospheric patterns for our shores being dictated by meso solutions. 

The model ens starting to vary widely by t72 wrt key energy direction and even U.K. Effects. 

I don't buy longer range ecm which will only amplify early mis judgements and unknowns without a strong forcing mechanism. 

Glosea has been particularly useless this winter, predicable given the lack of strong forcing. 

Cold is never far away. 

I fully expect opportunities to pop up in the t96-145 region and also for people to disappointed in the t72-120. 

So a pretty useless post from me if you looked for a forecast, but don't believe the models to much at the moment and never believe anyone if they tell you they know what will happen beyond a few days

[Gustywind]

GFS still looks the coldest option this morning, with the initial high pressure slightly further north allowing a more SE feed to take hold by t144 which starts to bring back in some colder uppers. More energy is sheered into the southern arm of the jet also.

The Atlantic begins to attack from the SW by t180 and with colder uppers in place we see snow for the West Country. I didn't look any further than this.

UKMO not quite so good as GFS but an improvement on yesterday as again the initial high pressure is slightly further north allowing a more continental feed for southern England.

ECM is pretty bad though. Again the initial high pressure is slightly further north, but by t168 it builds pressure again from the SW and we are left with a Euro high.

[Captain Shortwave]

To be honest given the large players around the Arctic seem to be the developing Canadian high and the low heights over Siberia, the Atlantic sector remains in a period of uncertainty, but the most favoured location to see cold air move south is unfortunately into the Atlantic feeding into the low heights already present there whilst heights near the UK stop any meaningful southwards progression of any troughing near Scandinavia.

Still the models do offer ways of getting some cold and potentially snowy weather.

      

The trough disrupts and engages a cold pool over France which moves towards the UK with the risk of some snow and it would be cold at the surface by next weekend. The south east is cold throughout the week with this slowly extended further north and west with time.

   

 

The ECM is pretty dire with your traditional Atlantic trough/Euro high setting up, you don't need a strong polar vortex to develop that pattern. Conditions before this would be chilly but not anywhere near the levels shown on the GFS above.

After my gaffe regarding the ECM ens, in fact the 12z were even more progressive in setting up a more mobile west to south westerly pattern with height anomalies over Iberia returning to near normal by day 10 with a positive anomaly from the Azores through France and a deep trough to our west/north west. Hopefully we will see this trend reverse.

Edited January 15, 2017 by Captain Shortwave

[IDO]

FWIW the 18z is currently easily the best performing run by the 4 GFS daily suites; SLP especially, so I would not dismiss up to D10:

Yesterday there was no cross-model agreement viz where the next wave of heights came from, but ECM have flipped to the GEM solution of a UK flanked two wave attack in our sector. Of course this is the worse case scenario and will mean the rest of January killed for any wintry potential. GEM maintains that theme but relaxes on the heights so we are left with a zonal mess from D6-10 at least (we know when a model picks up a new pattern it's bias it to overblow heights, so ECM likely to move that way). The GFS is therefore the only model to still maintain the one wave mid-Atlantic height build, but as expected those heights have downgraded with each run. It leaves the GFS solutions very messy re surface flows. The GEFS (here) support this pattern with nominal respect to the ECM solution. 

Very difficult to be confident after D6 viz the UK pattern. The only thing I am reasonably certain about is the continued cycling of the PV to Siberia then back to NE Canada, so opportunity for a blocked pattern is poor without forcing and, as the Azores has proved all Winter it cannot get better than a MLB without a Pacific wave to assist. Signs from the GEFS around D13 that there may be height rises in the Pacific region but la la land at the moment, and in any case that is for February. Of course the mobility of the PV has meant many opportunities for cold air to drift south, but unfortunately the UK has had more misses than hits. With seemingly no strat to trop forcing either we can see why the UK pattern has been quite repetitive this season; no resets to maybe get a better solution.

We can only hope the GFS outcome is in the ball park, though the variations on that theme in the GEFS are good and bad (for cold); if not then we are heading for a poor wintry setup for the rest of the month into early Feb. 

[bluearmy]

The unequivocal message from the ops is their drift towards the advertised ext ens mean/anomoly solution. As stated previously, we are fast running out of time for something to crop up in the mid range to scupper the sou'wester.  It's laudable for folks to see uncertainty etc but I'm seeing the opposite as the ops begin to hone in on where the extended eps /GEFS have been for the past few days. 

I reckon we have until tomorrow evening, perhaps Tuesday 12z's  latest to see an alternative route to deflect the jet onto a more southerly path in that 8/12 day period. 

The far off fi GFS and gfsp have begun to play with evolutions that hemispherically could look like a fast trop response to an ssw but they are possibly a few days ahead of that so perhaps not

it remains feasible that we could see the sou'wester verify but then have wonderfully amplified  patterns come into view to follow so might not be so bad watching the models whilst suffering/enjoying (delete as appropriate) any milder phase 

Edited January 15, 2017 by bluearmy

[Radiating Dendrite]

16 minutes ago, IDO said:

FWIW the 18z is currently easily the best performing run by the 4 GFS daily suites; SLP especially, so I would not dismiss up to D10:

Yesterday there was no cross-model agreement viz where the next wave of heights came from, but ECM have flipped to the GEM solution of a UK flanked two wave attack in our sector. Of course this is the worse case scenario and will mean the rest of January killed for any wintry potential. GEM maintains that theme but relaxes on the heights so we are left with a zonal mess from D6-10 at least (we know when a model picks up a new pattern it's bias it to overblow heights, so ECM likely to move that way). The GFS is therefore the only model to still maintain the one wave mid-Atlantic height build, but as expected those heights have downgraded with each run. It leaves the GFS solutions very messy re surface flows. The GEFS (here) support this pattern with nominal respect to the ECM solution. 

Very difficult to be confident after D6 viz the UK pattern. The only thing I am reasonably certain about is the continued cycling of the PV to Siberia then back to NE Canada, so opportunity for a blocked pattern is poor without forcing and, as the Azores has proved all Winter it cannot get better than a MLB without a Pacific wave to assist. Signs from the GEFS around D13 that there may be height rises in the Pacific region but la la land at the moment, and in any case that is for February. Of course the mobility of the PV has meant many opportunities for cold air to drift south, but unfortunately the UK has had more misses than hits. With seemingly no strat to trop forcing either we can see why the UK pattern has been quite repetitive this season; no resets to maybe get a better solution.

We can only hope the GFS outcome is in the ball park, though the variations on that theme in the GEFS are good and bad (for cold); if not then we are heading for a poor wintry setup for the rest of the month into early Feb. 

In all fairness though....looking at how much the verification stats chop and change is it not just a case of luck for a particular run latching on to the right pattern. It is like they are all stumbling around in the dark looking for a light switch.....one day the 18z will find it, the next the 12z etc.

[bluearmy]

haps 

14 minutes ago, Radiating Dendrite said:

In all fairness though....looking at how much the verification stats chop and change is it not just a case of luck for a particular run latching on to the right pattern. It is like they are all stumbling around in the dark looking for a light switch.....one day the 18z will find it, the next the 12z etc.

It's a bit like the old Brian clough quote where the  player comes and tells him something and then they discuss it and decide that Brian is right

The ops play around with many evolutions and the not snowy one is the run which always verifies! 

[Nick F]

Yes, with the EC high res and EPS/GEFS mean again singing from the same hymn sheet of pushing down the UK high and letting in the Atlantic once the SW Europe/NW Africa trough drops/fills, it seems a return of SWly flow to be the most likely path. This was picked up by the last Euro weeklies too. The block over Canada is just too far west to stop arctic cold air draining into a mean deep trough over the Atlantic. In a way, the high over the UK over the coming week is our downfall, because it can't build NE, N or NW, because of too much upper flow energy in this direction, so can only really sink or stay in situ.

The wildcard is the SW/Europe trough is stubborn to relax and may even be re-inforced by a southerly tracking jet developing over the Atlantic - but this looks like a low probability atm, but not to be ruled out for now IMO.

The positives I can see for longer term prospects into February, if you like cold and snow, is that the most likely return of SWlies may be brief, because the trop and strat PV is still forecast to be pulled toward Russia and the trop upper flow looks increasingly amplified upstream at day 10.

 

Edited January 15, 2017 by Nick F

[ArHu3]

One of the few times I see gfs going for cold in FI whilst ec goes for mild, usually it's the other way around and gfs usually turns out to be correct ultimately. 

 

 

BTW there is a marked difference between East and west Netherlands, so no mattercliffe the outcome you will be on the wrong side

Edited January 15, 2017 by ArHu3

[danthetan]

Where we go after 120hrs for me is anyones guess, it all seems to hinge on what happens to the trough in the Atlantic around 144hrs. ECM pulls all the energy over the top off the high sitting over the UK, UKMO seems to send most of the energy over the top but some underneath and GFS more or less splits it sending enough energy to at least drag colder air in for a time before pushing the high back into Europe, all these options go on to produce very different outcomes in the latter stages of GFS & ECM. With that in mind we know how the models always struggle to gauge the strength of any such blocking high so for me i need to see some consistency from the models around the 144 hr period before knowing which way were heading.

[Summer Sun]

P9 would warm things up a little

Not that it will happen of course

[festivalking]

Noticeable the lack of posts this morning. I'd suggest if UKMO was like gfs at 144 the thread was a bit active. I.e trust in gfs is a bit low!

[TEITS]

6 minutes ago, ArHu3 said:

One of the few times I see gfs going for cold in FI whilst ec goes for mild, usually it's the other way around and gfs usually turns out to be correct ultimately. 

Those ECM ensembles make me laugh. Talk about chalk and cheese compared to recently when the mean was well below freezing.

Im still not convinced the models are even correct between +96 to +144 at the moment. This is with regards to the modelling of the Atlantic low pressure you see at +96 to the W of Ireland. Compare the 0Z run with the 18Z and you will see what I mean.

[ArHu3]

3 minutes ago, TEITS said:

Those ECM ensembles make me laugh. Talk about chalk and cheese compared to recently when the mean was well below freezing.

Im still not convinced the models are even correct between +96 to +144 at the moment. This is with regards to the modelling of the Atlantic low pressure you see at +96 to the W of Ireland. Compare the 0Z run with the 18Z and you will see what I mean.

GFS never had mean below freezing, only ECMWF. ECMWF still has some cold in SE Netherlands, moreso than the usually much colder NE. It appears some EC ENS have the through going further west and the ridge further north, so still a little bit of hope for my area. A lot of snow already fell in the east of the netherlands but here just a few flakes  

[Guest]

Wow come on here and 80+ post since i went to bed last night so there i was thinking something good was kicking off with the overnight runs. Anyways 6z rolling out lets see if we can see some light at the end of the tunnel.

Edited January 15, 2017 by Guest
To move discussion on.

[Man With Beard]

30 minutes ago, Summer Sun said:

P9 would warm things up a little

Not that it will happen of course

Wow. What do you reckon, 17/18C??

[Ali1977]

2 minutes ago, Man With Beard said:

Wow. What do you reckon, 17/18C??

More like 13/14c in Jan I think !!

[stewfox]

38 minutes ago, festivalking said:

Noticeable the lack of posts this morning. I'd suggest if UKMO was like gfs at 144 the thread was a bit active. I.e trust in gfs is a bit low!

In recent years we have had more of a active Atlantic and more rain/storms coming through via it

I think some folk are down beat re ''potential'' GFS 18Z was better then 12z the 0z worse then 18z and it goes on.

15 Jan 2014

Potential is too far east.

Anyway GFS 6z is coming out what will it be up or down ?

Edited January 15, 2017 by stewfox

[Gael_Force]

37 minutes ago, Summer Sun said:

P9 would warm things up a little

Not that it will happen of course

Winter anticyclones are not all they seem. In this instance on p9 the surface is well below the 850's

 

[Ali1977]

Not far off a battleground scenario here !!

[IDO]

Bearing in mind the GEFS were strongly in support of the GFS 0z op, no surprise the 6z maintains the theme, which is consistent, but different synoptics to the ECM:

D5   ECM 0z

So big difference in uppers; 4-6c colder on the GFS. At 5 days one of the models is badly wrong again!