Winter Model Output Discussion 01/02/2013 12z onwards

[Tamara]

Its worth looking through the GEM ensembles. Most are a fair bit better than the GEM operational, and the majority are also a lot better than the GFS operational

[Gael_Force]

Interactive model bias page is not working just now.

Some cynical people may think that there is a reason for this...

http://www.hpc.ncep....bias/index.html

@Recretos do you have a link for the Korean anomalies. Not seen these online anywhere. Big Joe likes this model for sniffing out a pattern.

Here's the link for the KMA long range forecasts.

http://web.kma.go.kr/eng/weather/forecast/long-range1.jsp#

[snowmadchrisuk]

Its worth looking through the GEM ensembles. Most are a fair bit better than the GEM operational, and the majority are also a lot better than the GFS operational

The Gem Ensemble mean still collapses the ridge , but at least it gives Westerly's instead of SWly's.

Edited February 2, 2013 by snowmadchrisuk

[fergieweather]

Slight concern that there is no word on the extended outlook from IanF - would be interesting to see if MOGREPS is anything like the ECM at days 8/9/10

UKMO view remains consistent. They've just issued new 6-15d analysis based on 00z output.

Essentially cold / periodic snow / ultimate battleground set-up (latter developing Fri & with easterly push of uncertain scope continuing through to Monday). Into 10-15d period, Exeter continue story with MOGREPS-15 & DECIDER products showing strong NW/W influence with varying degrees of cyclonicity. Their conclusion is for the cold/wintry phase next week to be short-lived, through to about following Monday; the trend 10-15 d period then characterised by return to average or slightly below average temperatures. Thus, a consistent story from them over last 3 days in this regard, i.e. no real expectation of a *prolonged* cold spell of any note. Hope this helps.

[Tamara]

The Gem Ensemble mean still collapses the ridge , but at least it gives Westerly's instead of SWly's.

Looking through the individual member outputs gives the clearer picture I think . There are quite a few solutions that are lot more amplified than that mean suggests

[Cheshire Freeze]

UKMO view remains consistent. They've just issued new 6-15d analysis based on 00z output.

Essentially cold / periodic snow / ultimate battleground set-up (latter developing Fri & with easterly push of uncertain scope continuing through to Monday). Into 10-15d period, Exeter continue story with MOGREPS-15 & DECIDER products showing strong NW/W influence with varying degrees of cyclonicity. Their conclusion is for the cold/wintry phase next week to be short-lived, through to about following Monday; the trend 10-15 d period then characterised by return to average or slightly below average temperatures. Thus, a consistent story from them over last 3 days in this regard, i.e. no real expectation of a *prolonged* cold spell of any note. Hope this helps.

Dismissing the ECM operationals then which have looked ripe for longevity?

As a cold lover that doesn't want February to limp out I have to say I hope Exeter are wrong on this one.

[Tom Montalbano]

Its worth looking through the GEM ensembles. Most are a fair bit better than the GEM operational, and the majority are also a lot better than the GFS operational

So Tamara, where does that leave us now?

The N.Americans dug into their trenches over Greenland.

The Europeans lined up on the Norwegian coast.

Which leaves us in no-mans land, stuck between the opposing forces, surrounded by barbed wire, with the the fire of battle breaking over our head.

Will they feel the love on valentines Day and emerge from their trenches and have a kick-about?

And what news of the main man, Punxsutawney Phil, has he had his say! Certainly fair in downtown Croydon today, so will winter have another flight?

All will be revealed in the next few days, stay tuned. Fascinating stuff!

Regards,

Tom.

Edited February 2, 2013 by TomSE20

[Stu_London]

UKMO view remains consistent. They've just issued new 6-15d analysis based on 00z output.

Essentially cold / periodic snow / ultimate battleground set-up (latter developing Fri & with easterly push of uncertain scope continuing through to Monday). Into 10-15d period, Exeter continue story with MOGREPS-15 & DECIDER products showing strong NW/W influence with varying degrees of cyclonicity. Their conclusion is for the cold/wintry phase next week to be short-lived, through to about following Monday; the trend 10-15 d period then characterised by return to average or slightly below average temperatures. Thus, a consistent story from them over last 3 days in this regard, i.e. no real expectation of a *prolonged* cold spell of any note. Hope this helps.

Many thanks Ian - all adds to the uncertainty.

[fergieweather]

Dismissing the ECM operationals then which have looked ripe for longevity?

As a cold lover that doesn't want February to limp out I have to say I hope Exeter are wrong on this one.

To paraphrase our very latest from the duty Medium Range Forecaster: "....Recent ensembles have mostly NW types at first but with an increase of westerly types into the trend (10-15d) period... (and) more signs of a recovery of temperatures for most areas."

[bluearmy]

exeter following the broad ens message from ecm (and i expect mogreps). They are unlikely to do anything different. some on here are looking at the recent ecm ops and thinking - yeah, that makes sense and its what we expected to see based on telecons, experience and gut feeling (and a small modicom of hopecasting). if ecm op stays consistent then its likely that the ens will begin to follow suit. statistically, that remains the outside bet. there is no reason for exeter to forecast otherwise. by monday, it might be different though. if the op stays with its broad scandi block solution, the ens will definitely be showing this by monday and the meto forecast will be adjusted. currently, thats not what the maths says.

thanks for popping in and giving us the update ian. much appreciated.

[nick sussex]

So Tamara, where does that leave us now?

The N.Americans dug into their trenches over Greenland.

The Europeans lined up on the Norwegian coast.

Which leaves us in no-mans land, stuck between the opposing forces, surrounded by barbed wire, with the the fire of battle breaking over our head.

Will they feel the love on valentines Day and emerge from their trenches and have a kick-about?

And what news of the main man, Punxsutawney Phil, has he had his say! Certainly fair in downtown Croydon today, so will winter have another flight?

All will be revealed in the next few days, stay tuned. Fascinating stuff!

Regards,

Tom.

I think we can see looking at the two comparisons how relatively close both the GFS and ECM are in terms of the general pattern the point of difference is just the location of the PV and how much that troughing sharpens to the west.

In terms of the UKMO view given by Ian F I think we can view that as having that troughing closer but still quite amplified, some disruption hence the battle ground scenario.

Even the ECM doesn't show a clear trend for a strong high to the ne backing sufficiently west, its later synoptics are quite messy.

I don't think the UKMO update is that much of a surprise because at this timeframe the models may be more eager to push the cold further east.

Personally I'd be more worried about getting to the actual chance of a battleground rather than where the pattern goes from there.

The dropping south of that shortwave which gets absorbed into the Euro trough is far from certain, its an unusual set up and so is not to be trusted at this range.

[Tim Bland]

Sounds like the MOGREPS is more in tune with GFS than ECM which is disappointing. GFES ensembles are an improvement today. I think we shall know in the next few days where we stand. Other models will either come on board with ECMs idea or vice versa. The rest of winter is really in a knife edge with this, if the Atlantic comes back in we are running out of time for a pattern reset... Fingers crossed ECM Is on the money... I'd give it a 30% chance ATM

[Tamara]

All will be revealed in the next few days, stay tuned. Fascinating stuff!

Regards,

Tom.

All good fun along the way too as well Tom

The latest METO opinion in terms of the uncertain eastward breakdown extent next weekend has plenty of leeway for movement at this distance and so ensembles from around 10 days could easily be over progressive with this type of scenario and start to trend towards the more blocked suggestion of the ECM, or, at least show greater resistance to the advance of the westerly cyclonic type and lead to the sort of possibilities we saw in January . As you suggest, time, as always, will tell

[fergieweather]

Hi Bluearmy: yes, critical point here is that UKMO are under contractual obligations to issue the 6-15d briefing twice daily; bit of a poisoned chalice really, as it would be easy to fall into trap of chasing every model run and constantly modifying story. They simply write it as seen at here and now. Clearly, much can change.

Of course, as February continues the gradual (or usual!) increase in diurnal temperature range, plus additional potential for solar input as daylight hours extend, slowly mitigates against lying snow for extended periods in all but the most extreme cases at lower levels (especially in the south), but history demonstrates winter can retain a sting in tail nonetheless. The Fri-Sun/Mon period might prove of more widespread potential, but we shall see.

[Ian Brown]

Thanks Ian, obviously rejecting the ECM OP and perhaps favouring the GFS with perhaps less of an influential Azores High ?

[fergieweather]

Thanks Ian, obviously rejecting the ECM OP and perhaps favouring the GFS with perhaps less of an influential Azores High ?

No they'll follow MOGREPS-15 & DECIDER, coupled to EC. Never GFS at that range.

[cooling climate]

Its not just the ECM run though is it, the UKMO at t144 looks ripe for building heights to the north

northeast post t144. I would imagine lol that if the ECM folds and the GFS is proved correct (which

I do not think is the case) then a lot of posters will call time and close the book on this winter.

[Cheshire Freeze]

Its not just the ECM run though is it, the UKMO at t144 looks ripe for building heights to the north

northeast post t144. I would imagine lol that if the ECM folds and the GFS is proved correct (which

I do not think is the case) then a lot of posters will call time and close the book on this winter.

Quite possibly

This winter, i'm almost positive, would have been quite memeorable without the type of canadian vortex that has plagued us for the whole of the season. I think it is most likely an artefact of that much colder than average strat through late November and into December.

Edited February 2, 2013 by CreweCold

[Jason M]

Good of Fergie to post.

To be fair, this thread has been fairly quite in recent days and I think that this is in part because many don't really see anything that significant coming in th near future.

At this juncture were in the game, but I can't really bring myself to get particularly excited about the next week or so. If ECM verifies it coud be interesting and there is some support in the GEFS for this, but I just think its still odds against. I note SMs enthusiasm earlier which is good to see though.

I think its fairly high stakes now though. If we end up back into a westerly then I think that's it in terms of deep cold this year. That wouldn't preclude decent snow events though for a number of weeks into march.

Hopefully the 12zs will help somewhat.

Jason

[bluearmy]

Its not just the ECM run though is it, the UKMO at t144 looks ripe for building heights to the north

northeast post t144. I would imagine lol that if the ECM folds and the GFS is proved correct (which

I do not think is the case) then a lot of posters will call time and close the book on this winter.

Cc- ian posted some time back that uk gm at day 6 is not valued too much. They wont extrapolate an op run for several days if the ens data says otherwise. they just couldnt do it and justify it if they are wrong. We are able to do what we like - there is no one jumping on our backs.

Interestingly, the meto guidance ian just gave us was what i posted yesterday morning and then decided yesterday evening was a rather hasty decision and withdrew it. maybe i'm hopecasting too much?

[Captain Shortwave]

It definitely seems that the ecm was a rather extreme solution, on the other hand so is the gfs op at the other end of the spectrum. Longwave pattern wise the set up looks quite simple with the atlantic to the west moving in and a large block forming somewhere to our east. At this point we don't know where these 2 collide and will depend on the strength of the Canadian vortex and the strength of building shown by the high in Russia. It's probably wise to keep an open mind. Ian thoughts pretty much sit in the middle. A breakdown by the atlantic which is nowhere near as quick as the gfs operational, which at the moment is probably the wise decision at this point.

[Stu_London]

06z GFS ensembles don't really move us further forward

This will go 2 ways in my opinion.

ECM will collapse the cold spell it's op is currently showing in the space of 1 run (80% probabililty)

ECM will remain solid for cold spell while GFS, GEFS, ECM ensembles, minor models will come on board via small steps over 3-4 days. (20% probability)

Probabilities are just my opinion.

[snowmadchrisuk]

Looking through the individual member outputs gives the clearer picture I think . There are quite a few solutions that are lot more amplified than that mean suggests

I haven't had the time to look at every time frame, but I concentrated on +180 70-80% still have the Azores high there - 50% still to the West of the UK, So this is the sticking point for the 12z's . How far North will the Azores high get , How strong will it be , How far West will the Canadian Vortex be and the Position the Jet positions it's self. Strong Trough in the North Sea will also help any Westward correction .. As for next Week , I would expect the main Wintry potential to be in the W N/W on Tuesday , although this will mainly be in the form of Showers , the East Midlands may also get Cheshire Gap Showers,

[Glacier Point]

For what it's worth, I don't think the GEFS ensemble mean is that far off what the op ECM has been consistently advertising of late.

Day 10 GEFS mean H5 anomaly takes the upper level weakness across southern tip of Greenland and drives it (with some inevitable disruption) south-east into the western flank of the upper trough dominating Europe over the next 10 days. Operational GFS very clearly intent on driving this feature eastwards.

Note the development of anomalous +ve heights Svalbard as the trough digs SE and forces height rises to the NE.

The 850 hPa temperature anomalies to go with that suggest in the range 2-4C below average.

Days 11-15 GEFS H5 anoms are interesting in developing another ridge in the Atlantic (more upstream amplification). I suggest that this is consistent with the overall state of the GWO right now, favouring this type of anomalous ridge.

That makes the presence of the trough over Europe even more long lived as shortwaves are deflected NW-SE track, helping to advect the cold puddle westwards.

With 60 days of the season elapsed, we can also use persistence as a valid tool. H5 anomaly so far, might surprise a few....

For me this centres around the Euro trough and associated cold pool not really going anywhere fast. Just how much of an influence on the UK this has, open to some debate, but the broad pattern and general trending of ensemble means looks reasonable to give some confidence.

Edited February 2, 2013 by Glacier Point

[Frosty.]

Meto update sounded quite wintry really, certainly more wintry than the gfs is advertising. It sounds like there will be a low sliding down from the northwest next weekend with rain, sleet and snow, the rain more likely in the west, the snow further north and east, then wintry showers from the nw as a polar maritime flow sets in with more lows sliding southeast on a nw/se aligned jet. I still think there is enough time for something like the Ecm is showing if the cold blocking potential is being underestimated by mogreps/ukmo ens/gfs etc.