Model output discussion 25th Jan - The final third of winter beckons..

[Nick F]

3 minutes ago, feb1991blizzard said:

Does anyone know what the latest EC46 is suggesting please?

Can't be bothered to post all of them, but here's weeks 1-4, not exactly pretty ...

[Man With Beard]

6 minutes ago, feb1991blizzard said:

Does anyone know what the latest EC46 is suggesting please?

Almost winter's over quality. Little signs of northern blocking. This is the coldest it gets:

Maybe a hint of a Scandi trough there. Otherwise low pressure to the west.

Well, it got most of the northern height anomaly forecasts wrong, will it do better with these??

[feb1991blizzard]

2 minutes ago, Nick F said:

Can't be bothered to post all of them, but here's weeks 1-4, not exactly pretty ...

Thanks, it does tie in with my thoughts, that the strat vortex disintegration will happen just too late to please most, that week 4 looks like the trough will dive south, early March beast (week 5) perhaps?

[Allseasons-Si]

3 minutes ago, feb1991blizzard said:

Thanks, it does tie in with my thoughts, that the strat vortex disintegration will happen just too late to please most, that week 4 looks like the trough will dive south, early March beast (week 5) perhaps?

Looks like it

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=894&mode=0&carte=0&run=10

[Allseasons-Si]

There is a 1020 mb height's over scandi on the 18z control,with a little cutback towards Denmark,now that a sig shift from the 12z

these early changes make a big impact further on,we will see.

Edited January 26, 2017 by Allseasons-si

[Nick F]

7 minutes ago, Allseasons-si said:

There is a 1020 mb height's over scandi on the 18z control,with a little cutback towards Denmark,now that a sig shift from the 12z

these early changes make a big impact further on,we will see.

Minor surface pressure differences will make little difference to the likely outcome of deeper lows rolling in close to NW UK eventually, need to look at changes at the 500mb level and see if there is a trend over following runs. Those 2 charts aren't a great deal different from the 18z and 12z ops at the 500mb for the same times. The broad scale 500mb pattern has changed little between the 4 GFS ops today up until day 10, though positions of surface lows moving around the Atlantic trough will change the further one goes out, as will  surface ridge shapes.

[Allseasons-Si]

Cheers Nick,not looked at the anomolies etc just yet as i have not been in long(afters eh!)

but the atlantic has been held back again has it not!,last week the charts was showing the atlantic barreling through come this monday just gone and we have an ice day today for some,it just goes to show how much the weather chages in a week to what the models show prior.

[feb1991blizzard]

SPV over the pole on latest GFS, we are definitely going to need another warming in mid to late Feb,

[IDO]

The question is how long will the westerly pattern last? The Euro high lingering has meant what would probably have been a short and sharp zonal period now likely to last over 10 days due to the trop PV lobe being corralled to NE Canada with the aid of the Pacific ridge. The winter modus operandi is for any zonal period to be fleeting so just bad luck on this occasion that at the height of winter we have a persistent block to our east preventing a reset of the PV and giving little chance of any snowy outcomes.

The D16 mean does suggest a leakage of the strat PV from the Canadian area, but even at that range it would still mean a wet and windy with above average temps as a whole for the UK:

 Looking at the gEfS and there does not appear to be any consistent signal for a trop wave from either the Azores or Pacific and although the PV appears primed to be smashed up there is just no sign of any MJO forcing yet. The MJO has been a bit player this winter just when we needed it to be the star of the show.

We know the models are very good when a zonal period is forecast, so the upcoming long wave pattern is probably a done deal. The next week modelling should give us a guide to how the trop NH profile will develop once the blocking has dissipated and the PV can spread over the polar regions freely. Unless we get some help from the strat, getting any HLBs look a long shot (based on this winter's poor efforts) so we will be hoping short wave developments will bring us transient shots of cold. No clear signal from the GEFS yet.

[mb018538]

Not surprising there isn't much comment when this is the forecast:




You can either have windy with rain on the UKMO run, or very windy with rain on the GFS run.



From a couple of days back, you can see now that the rainfall is progged to still be heavier in the west vs the east, but totals starting to mount up in the 6 day period, with more to come after.

Looking a bit further ahead, and above, and things ain't pretty:

[Ali1977]

I noticed that Ian F said possibly weak phase 6 MJO by 2nd weak of Feb combined with strat warming yields uncertainties on into Feb. Now we know warming can help with a chance of a disturbed PV, what would a weak phase 6 bring to the party if it happened? 

[Paul_1978]

Well there are things happening in the strat, so I'm not as convinced things are going to be as relentless as they seem at the minute. Surely not long before we see more favourable output once the models pick up on the signal?

[Chris K]

1 hour ago, Paul_1978 said:

Well there are things happening in the strat, so I'm not as convinced things are going to be as relentless as they seem at the minute. Surely not long before we see more favourable output once the models pick up on the signal?

Hard to tell. The problem is, in previous winters where it has ended up relying on some hope from Strat warmings into February, we either have ended up with a cool wet spring or diddly squit... Also, I do not really know much on the subject, but surely there is a normal seasonal warming anyway as we head towards Spring?

It may well cause something more favourable during February, but I don't feel too confident when we are in this position to be honest. There are also other factors to take into account. I wait with interest to see how long this potential "active" weather lasts.

Edited January 27, 2017 by Chris K

[stodge]

Morning all

After yesterday's remarkable ice day in the SE, a significant change is imminent with a return to Atlantic-dominated weather.

Too early to get an exact feel for storm tracks and intensities but the general view from the models is of a succession of vigorous depressions moving SW - NE up the west of the British Isles with copious amounts of rain and wind especially the further west you are. The secondary features could be the real problem as one or two of them deepen explosively in the flow.

The Jet is strong and over or just to the south of the British Isles so all areas will see some wind and rain and the latter won't be wholly unwelcome after an extraordinarily dry winter.

We're in this for at least 14 days in my view - I do think the upcoming warming and further activity will weaken the stratospheric vortex - the 10HPA temperature rises from below -80c now to -60c in a fortnight so that for me is an indication of a weakened PV which may be vulnerable to further and more advantageous displacement. The GEFS members are starting to sniff some options at the furthest edge of FI with both Greenland and Scandinavian blocking options from one or more of the members though it has to be said the majority keep the Atlantic flow.

Going beyond mid-February I still see plenty of opportunity but as always we need a fair bit of luck and the cards to fall right. The models aren't going to make pretty viewing (unless you like stormy conditions) for the next week or so - by then, I think we will start seeing some eye candy in FI and the chase can begin in.

After 10 days of cold, I won't mind some warmer weather.

 

[MR EXTREMES]

The mjo has been static for sometime and with current model runs showing pv to be around Canadian side I don't think Greenland block very favourable at all.

Although scandic block still a possibility but like most of this month will it be close no cigar repeated.

But with uptick in solar output I do believe for awhile we will have to endure something milder perhaps with cooler or colder nw flow if lows make it across the uk.

Jet streak beefed up to which seems ironic as solar activity rises so the vortex gets wilder and of coarse feeding jet streak.

In regards to the stratospheric warming it would seem we need more juice to get a reversal.

But even so it's rather worrying seeing the last month of winter going out with a wimper.

Let's hope we get a double east qbo pattern next winter.

Anyway at least the heating bills will be a little relaxed for awhile and incredible how close we come to joining Europe's snow fest.

Still better than last year perhaps mid Feb maybe March we might see some snowfall here on the sunny Costa del south coast.

There still some wintry weather to be had especially this evening and tonight as fronts push in perhaps slow approach so east especially northern eastern England eastern Scotland.

Perhaps some suprises here

[Paul]

Just wanted to share a new feature we've been working on. It's the first mini update of a much wider set of new model and forecast viewers - this one being a global, interactive jet stream viewer. You can move the globe, zoom in and out etc etc. 

Hopefully it'll prove useful!

http://www.netweather.tv/index.cgi?action=global-jetstream;sess=

[mb018538]

Not that is in any way going to be the exact chart for 384 hours time...



By the end of the 6z, the PV is almost entirely closed back across the North Pole. I think with the SSW, we shouldn't pay too much attention to what's going to happen by mid-February, I suspect it could end up very different to the endless zonal train that the GFS has churned out the last 2/3 days. It tends to get zonal and run with it in my opinion.

[stodge]

48 minutes ago, mb018538 said:

Not that is in any way going to be the exact chart for 384 hours time...



By the end of the 6z, the PV is almost entirely closed back across the North Pole. I think with the SSW, we shouldn't pay too much attention to what's going to happen by mid-February, I suspect it could end up very different to the endless zonal train that the GFS has churned out the last 2/3 days. It tends to get zonal and run with it in my opinion.

Indeed but it's not an implausible evolution and it may be a weakened PV can be displaced more easily in mid-February. I've seen elsewhere an argument it might finish up over Scandinavia - the Ensembles on the 06Z are solid to T+240 so it's going to be a question of watching storm tracks and rainfall and wind numbers and again the secondary features could be the real problems. Into far FI and some other options are on the table as you'd expect.

In the more immediate, quite a severe feature for Ireland and the SW in terms of rain and wind - the battleground is obvious here with the block over the Ukraine ridging toward Scandinavia meaning the Atlantic LP isn't moving up to Scandinavia but recurving back NW into the Atlantic. The story of FI is the gradual transition from a West-East battleground to a more traditional North-South one. 

[warmintim]

This will almost certainly get deleted and fair enough, but just because there hasn't been a snowfest, this WINTER cannot be denigrated as a long autumn, unless you are volunteering to scrape the ice from my windscreen when its -8 deg C? In my location we've had more frosts than I can count, including several that have lasted all days in sheltered spots.

We are clearly entering a period where the atlantic weather will edge a few hundred miles further east - it doesn't look like a return to classic zonality. With the SSW (or near SSW) in play it seems likely the the dice are being thrown and this may start to show in the later stages of the models fairly soon. And its not even Feb yet. 

[Paceyboy]

I know everyone has model fatigue but just a glimpse of sudden height rises around Norway at t72 on latest gfs?

Possible? Probably gone next run! Sorry on phone so can't post chart. 

Edited January 27, 2017 by Paceyboy

[bluearmy]

1 hour ago, Paceyboy said:

I know everyone has model fatigue but just a glimpse of sudden height rises around Norway at t72 on latest gfs?

Possible? Probably gone next run! Sorry on phone so can't post chart. 

No doubt the blocking to our east is stronger than first modelled and its desperate to fight back against the jet but we now approach a period where the jet will be too strong and too sustained for the block to hold it west of the uk 

I'm sure that there will be the odd disruption thrown in over the next 7/10 days and when the chart first appears there will be great joy and happiness on here - but it will be flattened by the next surge of the jet with very low heights predicted to enter the nw Atlantic and feed the northern arm

the best we can hope for is a general dropping of heights over the whole of nw Europe so we might see runners in the base of the trough pull some colder continental air ahead of them as they run towards us

even that will probably be forlorn now that the near continent is going to warm up

[snow freak]

1 hour ago, warmintim said:

This will almost certainly get deleted and fair enough, but just because there hasn't been a snowfest, this WINTER cannot be denigrated as a long autumn, unless you are volunteering to scrape the ice from my windscreen when its -8 deg C? In my location we've had more frosts than I can count, including several that have lasted all days in sheltered spots.

We are clearly entering a period where the atlantic weather will edge a few hundred miles further east - it doesn't look like a return to classic zonality. With the SSW (or near SSW) in play it seems likely the the dice are being thrown and this may start to show in the later stages of the models fairly soon. And its not even Feb yet. 

Yes I kind of agree that at least we have had some frosts this winter, unlike 2015/16, however I can understand what the other poster is saying too.  It's simply the lack of snow that is making everyone so fed up.  We had no snow at all last winter and this winter we have seen just 1 day of snow falling which didn't even last on the ground for more than a few hours.  I hardly call that a decent winter....or a winter at all really.  In our location you could more or less expect at least 5 days of snow either falling or lying in the past few decades but it really seems as though those winters are gone and we are lucky if we get 1 or 2 days of the white stuff now.  We do seem to have more of a continuous Autumn and that even goes for our summers too, which have not been great either in terms of heat and sunshine, just mediocre temperatures and hazy sunshine or cloud.

[Polar Maritime]

Just another reminder to use the winter or model moan thread for chit-chat. Please continue with Model Output related discussion, Thanks.

[mulzy]

The APERGE remains fairly blocked at 114 hrs - it's rather on it's own at the moment.

Edited January 27, 2017 by mulzy

[Singularity]

I do sense the blocking won't be fully overrun and will tease us on numerous occasions during the first week or so of February. Only after that are there signs the jet could have a fair bit of the sting taken out of it (MJO again and GEFS has shifted part way toward the other models and the more active eastward propagation to the Pacific. It's actually a little encouraging).

Until then, GEM may provide some entertainment as it settles into one of its age-old habits and develops every slight disturbance into something vigorous;