Model Output Discussion - Cold spell ending - what next?

[Scandinavian High.]

46 minutes ago, mulzy said:

Indeed nws - it's looking ominous.  Another snowless winter is possible in London to add to the many in recent history.  What makes this winter different is the ridiculous level of ramping by experts and amateurs alike.  Anyway, we have 5 or so weeks of winter left so who knows but the signs are not good (see chart below).

 

And that chart is 10 days away I put my house and my car on  that will not play out like that. And knowing my luck. It will

[Don]

9 minutes ago, bluearmy said:

I assume phase 8 would be post day 16 so won’t show on the three ens suites 

but the 46 also goes to day 20 so it would seem that phase 8 isn’t before feb 8th at the earliest 

Not great compared to earlier in the week when MJO forecasts were more amplified?  So, it would seem not only do we have a less favourable strat moving forward, we now also have less help from the MJO?! 

[blizzard81]

The EC46 looks much improved to me compared to the last couple of days. More retrogression to the north west and leaning back towards the seasonals in terms of anomalies. 

[Don]

6 minutes ago, blizzard81 said:

The EC46 looks much improved to me compared to the last couple of days. More retrogression to the north west and leaning back towards the seasonals in terms of anomalies. 

Yes, I thought tonight's update looked slightly better than recent runs.  However, need it to gain some traction.

[SnoFlakeEar]

4 hours ago, WYorksWeather said:

GFS seems to have binned what looked like an emerging cold or at least average signal on tonight's GFS 12z ensembles, when you compare to yesterday.

There is a lot of scatter in the extended, but I'm really not seeing a cold signal here. Exceptionally mild from Sunday night through to the 26th, then something nearer average, but likely still a little above given the mild nights. There is a cluster of colder ensemble runs, but this doesn't look like anything more than the usual scatter you'd expect to see at this range.

Of course, it will still feel cold, but I think people are in danger of losing perspective here. Even looking at very warm London stations such as Kew Gardens, the late January means on the GFS chart above of 6-7C are at least 1C above average. I've checked charts for elsewhere, and whilst the numbers differ, the general trend is very similar.

Overall, the smart money for at least the current horizon of the model runs is that temperatures will be milder than average, and at times very substantially so.

This is emphatically not a winter is over post, though. All of February is still well outside the reliable.

ECM to compare and contrast later, of course...

So basically to summarise your post standard winter fare for UK?

[WYorksWeather]

1 minute ago, SnoFlakeEar said:

So basically to summarise your post standard winter fare for UK?

I wouldn't really say so, no. It's somewhere between slightly above and well above average for the time of year.

As I mentioned in my post, normal even for London would be nearer 5-6C or so. The 21st to the end of January is looking much milder than that overall. The GFS mean at face value is around 8-9C from 21st to 26th, then around 6-7C, and it often under-reads.

[Singularity]

2 hours ago, mulzy said:

Serious question - are MJO analogues flakey at the best of times and not worth the paper they are printed on in a world that is warming very fast?

For broad patterns they have value if not taken too literally, more as a suggestion which way the weather patterns will attempt to go. After all, the MJO is one of many forcing factors. That’s why we don’t see forecast models just following MJO composites even at 7+ days lead time when there here & now becomes increasingly less relevant I.e. persistence of the near term pattern tendency becomes increasingly inaccurate.

Long story short, while I can see plenty of scope for a high to set up over Scandinavia by early Feb, I think it’s a lot more up in the air whether it’s positioned & orientated in a way that’s notably cold for the UK (let alone snowy). The HLB dominated seasonal modelling for Feb is very intriguing in this regard - it seems it must be tied to subsequent developments… but can we trust that those will come through? If only it was that easy!

[saintkip]

1 hour ago, blizzard81 said:

The EC46 looks much improved to me compared to the last couple of days. More retrogression to the north west and leaning back towards the seasonals in terms of anomalies. 

EC46 is a really good model that never gets it wrong, honestly guv

[KTtom]

12 hours ago, Frosty. said:

 

I think it was Singularity (pro) who said yesterday to take Scandi highs with a large dose of sceptism in extended model forecasts. He/she appears to be correct, just as we head todards the T -7days the gfs is having none of it, infact starts to transfer a segment of PV to our north east around the day 10 period. Much like the Greenland high this week, it looked all to 'clean' at distance and then models pick up issues with the idea as we gen within day 10...hence the reason for asking about resolution last week.

Anyway...better post a model chart...gfs day 10

Edit: Sorry Frosty, no idea why you are in my post

Edited January 20 by KTtom

[northwestsnow]

EC day 9 is horrendous..

Big TPV sat exactly where we coldies dont want ...

On a more positive note there is huge blocking over NW Russia ..

Edited January 20 by northwestsnow

[Lukesluckybunch]

So the signal for a scandi high..has all but disappeared..

7 minutes ago, northwestsnow said:

EC day 9 is horrendous..

Big TPV sat exactly where we coldies dont want ...

On a more positive note there is huge blocking over NW Russia ..

Absolutely nw..just too much energy in that northern arm

[Kentspur]

I hope the yellow ensemble members on GEM is the trend setter... . Looks very mild

then perhaps a little closer to average atm on most ensembles

Edited January 20 by Kentspur

[snowking]

39 minutes ago, northwestsnow said:

EC day 9 is horrendous..

Big TPV sat exactly where we coldies dont want ...

On a more positive note there is huge blocking over NW Russia ..

Whilst that immediate signal in our locale at that snapshot is not the most appealing (although I have quite enjoyed the dry and sunny element this week I must say), if you’re looking for something to help nuke that great big purple blob then that’s a pretty decent Wave 2 precursor pattern - Russian high, Aleutian low.

[Gowon]

Seems we're going to have to get through this period of strong jet to the NW for a few more weeks before anything decent happens; at least there's no endless rain being shown on the models- I reckon the first week of Feb things will start to improve judging by the models.  

The KMA goes crazy at the end by splitting the blob into little bits over the arctic:

 

[sunnijim]

To try and lift the mood a little and taking the Russian High appearing as the crumb of comfort.

Whilst acutely aware that no historical matching is ever going to be an accurate forecasting tool, I did look over some  of my own  records and noted a clear  trend  for heights to build temporarily to our South after a spell of turbulent weather and a bias ( default) position in the modeling to continue the pattern for weeks.( on most occasions a new strong  signal is picked up at the start of the new weather type) so Wednesday or Thursday next week if this holds true.( This area of my own data since 2004)

Not always what we are looking for from a cold perspective it needs noting, a return to Atlantic Lows was the form horse historically with a couple more colder episodes thrown in before Spring BUT on a couple of occasions I matched where we are now to the emergence of a dominant Russian High.( this area of data since 1983)

Stormy, Euro Heights ( under a week), a weaker attempt at the return of zonal  and then floodgates from the East ( took about two weeks after the last deep low) which would be Tuesday 23rd on this occasion and snow shovels for Tuesday February 6th ( this was written as a young boy aged 12 to 19) so simplistic talk of "deep Lows"," High over Europe"" High moves away" "light rain pushes in From SW", "High over Russia", "snow from East"to quote my old notes

Looking back over Winters that have shown stormy spells and colder drier spells interspersed, I couldn't find a match ( since 1983)  where we entered the remaining months of Winter ( late January and February) under a Euro high or a close equivalent as models / ensembles  would have us believe today.

[IDO]

I have not noticed the models much recently as I think nothing cold is likely until week 2 of Feb, once the Euro high has retrogressed to the Azores/Atlantic corridor. The GEM mean hinting at that by D16.

D8-16 GEM & GEFS mean:

 

But it is a slow process that has been delayed by the shenanigans of a stalling Euro ridge post D8 as it clears east. Both means have little upstream developments to suggest we can break this tPV pattern. The mean Pacific/Asian tPV segment in FI leaks partially to the Greenland sister, making any wave breaking in the Atlantic harder. 

Until we can disengage the Greenland tPV, we will likely experience the jet's northern arm dictating the flow, making it hard for sustained waves to reach higher latitudes downstream, especially in our NE/east quadrant. So, there is still no optimism of changes before week 2. The usual caveats of background factors popping up.

[Paul]

Just posting this in here as well as the Storm Isha thread, as it's well worth a read. 

Synoptic Analysis: Storm Isha arrives Sunday night

WWW.NETWEATHER.TV

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A synoptic analysis looking at the development and impacts of Storm Isha arriving Sunday night and expected to bring widespread gales with potential for disruption.

 

[AO-]

Good Morning all,

Since I do not have a lot of experience viewing the NHP, what strikes me at the moment is the shape of the vortex by day 5. We've often seen the vortex being shaped this way over the Atlantic between Canada and Scandinavia. This Implied often a strong jet with a zonal flow. Does anyone have any examples that are similar to this one that lead up to a proper cold spell? I would suppose this synoptic pattern leaves the door open for retrogression of the Siberian high. GEM, GFS and EC at day five. 

 

Edited January 20 by AO-

[Mike Poole]

ECM clusters T192-T240:

All show a ridge through the UK to Scandi, but this is much stronger on cluster 2 (20 members) than cluster 1, which has a more westerly influence. 

T264+:

The Scandi high option seems to no longer be on the table this morning, with a UK high being the destination in cluster 2, whereas the more mobile cluster 1 eventually puts up an Atlantic ridge.  This is the retrogressive option - and this seems to fit with the signal from the seasonals, and also the ECM 46 - which, as @blizzard81 noted earlier, was a stronger signal for heights to the NW yesterday than recent runs.  

I’m still not wildly optimistic that a cold spell is on the way in February, but all the evidence seems now to suggest that if it does materialise, it will be from height rises somewhere to the NW.  

[Jacob]

2 hours ago, Kentspur said:

I hope the yellow ensemble members on GEM is the trend setter... . Looks very mild

then perhaps a little closer to average atm on most ensembles

Yes please!!!

[Northern Sky]

1 hour ago, Mike Poole said:

ECM clusters T192-T240:

All show a ridge through the UK to Scandi, but this is much stronger on cluster 2 (20 members) than cluster 1, which has a more westerly influence. 

T264+:

The Scandi high option seems to no longer be on the table this morning, with a UK high being the destination in cluster 2, whereas the more mobile cluster 1 eventually puts up an Atlantic ridge.  This is the retrogressive option - and this seems to fit with the signal from the seasonals, and also the ECM 46 - which, as @blizzard81 noted earlier, was a stronger signal for heights to the NW yesterday than recent runs.  

I’m still not wildly optimistic that a cold spell is on the way in February, but all the evidence seems now to suggest that if it does materialise, it will be from height rises somewhere to the NW.  

I'm actually quite glad about that. Chasing a Scandi high almost always ends in disappointment and after counting down this last cold snap for what feels like 3 months I'm not sure I can take it. 

[swfc]

Morning. Looking at the gfs at 10pha the tpv looks quite weak. Not my field bit why isnt the mo showing a weaker pv?? Tia 

[bluearmy]

23 minutes ago, swfc said:

Morning. Looking at the gfs at 10pha the tpv looks quite weak. Not my field bit why isnt the mo showing a weaker pv?? Tia 

Not sure what you’re asking but I would urge people to use the wind flow 10hpa charts to judge where the spv is rather than the temps 

this run makes more sense to me if we are to see the strat and trop vortex remain coupled as has been the case for some time now 

Having the spv over Barents and an upper scandi ridge wasn’t a recipe that made me comfortable

[Mike Poole]

The GFS 6z in FI gives a pointer as to what we might be looking for if the retrogression idea comes off, from T192:

850 temperatures at T384:

[MJB]

PV absolutely hammered at the end of the GFS 6z...........promising signs . Yes it's as far out as one could go, but lets see if it's a trend