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

[IDO]

7 minutes ago, Jonathan Evans said:

Well the models produce proper cold today 2C max - feels like winter - much better than the last transient northerly attempt 

Don't know about others but cold for cold sake doesn't do it for me. I want cold because it can lead to snow; the current spell has had no potential for that; prefer a warm high and low fuel bills!

Just looking at the CFS monthly and they tie in with what the Met suggests. February more of the same:

anomalous heights Feb

HP to the east, Azores high with probably a cold rain scenario for most. Any SSW due late Feb bringing an awful cool first half of Spring (again).

March anomalous uppers April: 

So assuming these charts reflect an SSW, likely it will be too late for anything but a rotten cool rainy Spring.

[Catacol]

1 hour ago, bobbydog said:

The solar "uptick" is a minor blip. If you've given up on this winter, the next few could be interesting due to just that. Solar minimum before next winter?.....

An interesting comment. I think this winter so far has been notable for the accuracy of the overall Nina template, something bemoaned many weeks ago and first highlighted as a danger by Tamara. Insufficient Pacific amplification to force a properly high lat block.

However the other very obvious point has been the lack of any kind of Atlantic momentum. Our super Euro block has pulsed to the west of the uk and sat bang on top of us but at no stage has it effectively been blown away. Last year the strength of the Nino drowned out any other signal, but this year with a near neutral ENSO we have seen suggestions that declining solar activity has been a significant factor in depowering the jet.

There is a strong body of opinion that we are heading for a deep solar minimum. Fred may hate any talk of MJO forcing but perhaps he might chime in here seeing as the model thread has gone quiet and the 7 day outlook is uninspiring at present. The growing consensus is that we will head back towards a gentle Nino come summer. Provided this doesn't become rampant this is a good background pacific pattern to head into autumn/winter with. Add into his a move further into solar minimum territory and what must surely be a eQBO phase and next winter may indeed have a lot going for it. If the melting arctic (not a good thing at all) creates positive snow cover feedback once again then this too may suggest an interesting winter season.

Remainder of January 2017 now looks poor unless you work in the Scottish Ski industry where some snow will be welcome. Last chance saloon for lowland uk in February with Strat impacts from warming and perhaps a maturing MJO signal providing some amplification. However the dice have mostly failed to roll the way of snow this year so optimism is sure to be tempered. Wouldn't rule out some mid Feb excitement but unless we get a major warming downwelling quickly (bear in mind there hasn't been an obvious troo/start connect been working this year so no guarantee at all of this) then 2016/17 will probably go down as a very blocked, very dry winter with decent frost but little wintry precipitation and pretty average temperatures. A deepening solar minimum will then be a relevant discussion point for the next several winters to come.

Edited January 21, 2017 by Catacol

[Singularity]

3 hours ago, bluearmy said:

I'm still intrigued by your fascination with the MJO - given that the difficulty in obtaining a coherent and convincing forecast for it all winter  I fear for your sanity

Years of research have identified it as the leading forcing mechanism on sub-ENSO timescales - but only when it's active of course.

In the next fortnight we're especially reliant on it remaining active and propagating east to set in motion a chain of events that may alter the global momentum budget in ways we can benefit from by not long into Feb - Tamara had a detailed look at this a number of days ago. Perhaps even a week ago already; time flies when you're busy.

If it falls through, I struggle to find much reason to expect more than transitory cold/snow opportunities in a mobile flow, those chances coming along if the jet (hence polar boundary) tracks far south enough overall. I suppose that'll at least be more varied, hence interesting, than most of this winter has been.

It's tricky to figure out what the cold/mild balance will end up being, due to the tendency for GFS in particular to get a bit carried away with N. Atlantic cyclogenesis when the vortex drifts over NE Canada, which in turns leads to an overestimation of further cold air transport into NE Canada, more deep cyclones, and so on.

 

By the way - it suddenly hit me what's changed for Wed-Fri in terms of the Atlantic v. Block situation; the pace with which the trough disrupts has been increased with each new run, such as to cut-off a low by as early as Wed evening now, which just as with river systems means the jet stream can resume a more direct course.

 

Oh  yes - you can have too much of just about anything when it comes down to it!

[The Weather Dragon]

2 minutes ago, abbie123 said:

Game for what we all new that we where going to get some  unsettled   Weather later part of January it's been very cold here in the south east of England for 2 weeks with hard frosts and my snow man is still in the garden I'm looking at February for the next cold shot.

mentioning 'game over' 100% post removal guaranteed. I meant game over for any undercut or retrogression of current block. Let's see where we end up after this unsettled spell. I can see another euro high tbh 

[chrisbell-nottheweatherman]

On 21/01/2017 at 07:38, IDO said:

The GFS and GEFS have been very consistent with the forecast in FI, a zonal period as the PV moves back towards our NW, though they underestimated the euro high viz the PV movement currently so we have stalled the UK HP pattern for a week, with pretty much no chance of a snowy period ever developing from that high. For the SE the temps have been underplayed by the models as we have seen over 7.5c, 6.5c and 6.5c highs the last three days in the warm feeling sun, so very pleasant compared to some of the cloudier area further up the UK.

The D16 mean has been instructive as to the pattern and remains as of late:

That's a solid mean and a very poor starting position as of Feb 5 in what is a short month in any case. Not a lot to say other than from experience when a period of zonality is predicted the confidence is very high for that signal and although we missed the initial surge, the return of the lower heights over the UK is nailed this time due to the synchronicity with the negative EPO during the same period; forcing of the PV to be corralled to NE Canada/Greenland.  

 

IDO, given your continued reliance on (and explicit confidence in the predictive power of) long-range GFS mean outputs, might I enquire as to whether you have read, ignored or disagreed with, the following post, please?

https://www.netweather.tv/forum/topic/86906-model-output-discussion-29th-december-into-mid-winter/?do=findComment&comment=3528529

I may have no formal meteorological training, however, as a lowly biology graduate, I had to study a semester of statistical analysis in my second undergraduate year.  Admittedly, it was 15 years ago now, and I can't recall much in the way of specific details without checking back over my lecture notes, but I do recall that means were regarded as next to useless without some measure of standard deviation or a similar measure of dispersion.  I feel the poster I linked to has made a sensible suggestion as to how we might apply this principle to the publically-available NWP model outputs, i.e. by always posting the NH ensemble spread chart with a post-10 day mean in order to determine where geographically such uncertainty lies.  Though it's beyond my ability to do this, I have seen such information be used by experience model viewers here to elucidate which parts of the evolution shown by mean outputs and operational runs are crucial in terms of how the situation evolves over the 10-14 day period, and, in so doing, to derive at least a qualitative idea of how much to trust mean charts.  In your post (quoted above), you appear to me to take the 16 day mean literally, as you state

Quote

...from experience when a period of zonality is predicted the confidence is very high for that signal and although we missed the initial surge, the return of the lower heights over the UK is nailed this time due to the synchronicity with the negative EPO during the same period...

which makes it seem as though you are certain in your own mind that that mean output is representative of the likely path as opposed to being an unrepresentative merging of two or more possible and very distinct patterns, i.e. where ensemble members may fall into 2 or 3 distinct clusters, yet the mean shows a blending of these solutions unsupported by any individual perturbations. 

I ought to say that, in this case, I suspect that your analysis may be correct, but I do wonder whether reliance on a mean solution without consideration of how representative that solution may be in terms of the spread of data is necessarily a sensible policy or something we ought to be encouraging those new to viewing deterministic NWP to adopt.

Edited January 22, 2017 by chrisbell-nottheweatherman
Correcting typo.

[IDO]

Not much change from the GFS. At D15:

Edited January 21, 2017 by IDO

[Singularity]

It seems there aren't as many winter gale fans on the forum as I imagined these days; the weekend into next week is starting to look like a bit of a wild ride with wind gusts often in the 50-60 mph range across wide areas. Though GFS does tend to get a bit carried away to the reality could be nearer to 40-50 mph for most - but still 60 mph in exposed areas.

 

 

Briefly on the longer-term; the cross-polar transfer of very low heights has not gone as smoothly on the 12z GFS (right-side) as it did on the 06z (left) and indeed all other recent operational runs. This is more akin to recent ECM runs so it will be interesting to see if the jet becomes more meridional ('wavy') across the N. Atlantic in the 10-14 day period.

Edit: The stratospheric warming also persists more at 30 hPa than in the past few runs(06z on left, 12z on right). I wonder if 10 hPa has also improved?

 

 

Edited January 21, 2017 by Singularity

[Singularity]

Just when you think you have the removal of the cold weather figured out, UKMO comes along and slows down the cutting-off process, resulting in the low hanging out by Portugal on Friday, while the frontal boundary takes until the afternoon to reach the SE (so an extra freezing morning possible down there), and the upstream pattern looks liable to build a ridge across the south for Saturday resulting in a less wet but still mild and quite windy outcome.

With that, I'm off to enjoy a nice long evening of not looking at the models - apart from a brief scan through ECM of course 

[I remember Atlantic 252]

not bad! ECM at 168, high pressure closer, less wet/less windy, than last few ECM and GFS runs

Edited January 21, 2017 by I remember Atlantic 252

[Singularity]

Well ECM has raised a lot of questions regarding how fast the low cuts off to the SW Thi-Fri or if it even does at all.

In not doing so but retaining a negative tilt ECM appears to keep the Atlantic from fully rolling through until the weekend. Similar to where UKMO appears to be headed, it keeps the south under more HP influence through at least Sat.

Could this proposed wet and wild spell still go the way of other recent ones in 7-10 day modelling i.e. HP manages to hold its ground for the most part across the south? You know what, it wouldn't surprise me!

Edited January 21, 2017 by Singularity

[nick sussex]

14 minutes ago, Singularity said:

Well ECM has raised a lot of questions regarding how fast the low cuts off to the SW Thi-Fri or if it even does at all.

In not doing so but retaining a negative tilt ECM appears to keep the Atlantic from fully rolling through until the weekend. Similar to where UKMO appears to be headed, it keeps the south under more HP influence through at least Sat.

Could this proposed wet and wild spell still go the way of other recent ones in 7-10 day modelling i.e. HP manages to hold its ground for the most part across the south? You know what, it wouldn't surprise me!

If that's the best you can do in terms of raising some interest then we're in real trouble! lol The GFS 18hrs run for cold is atrocious and the worst thing is the rock solid consistency between outputs. This is always a bad sign and never happens if any cold is in the offing.

[Newberryone]

12 minutes ago, Singularity said:

Well ECM has raised a lot of questions regarding how fast the low cuts off to the SW Thi-Fri or if it even does at all.

In not doing so but retaining a negative tilt ECM appears to keep the Atlantic from fully rolling through until the weekend. Similar to where UKMO appears to be headed, it keeps the south under more HP influence through at least Sat.

Could this proposed wet and wild spell still go the way of other recent ones in 7-10 day modelling i.e. HP manages to hold its ground for the most part across the south? You know what, it wouldn't surprise me!

Well I for one hope the Atlantic does steamroll through and flattens once and for all that euro high that has sat there for most of this so-called joke of a winter. Seeing those isobars tightening rapidly resulting in some explosive cyclogenesis conditions is a worthy and fascinating alternative/substitute for this bland nothingness we've had to endure for what now seems like an eternity. 

[bobbydog]

7 minutes ago, Newberryone said:

Well I for one hope the Atlantic does steamroll through and flattens once and for all that euro high that has sat there for most of this so-called joke of a winter. Seeing those isobars tightening rapidly resulting in some explosive cyclogenesis conditions is a worthy and fascinating alternative/substitute for this bland nothingness we've had to endure for what now seems like an eternity. 

Yep. Just been looking throught the 18z and its a very stormy run, starting around next weekend.

Then in deepest FI we get this-

I'm driving to cornwall that day, could be an 'interesting' drive. If cornwall is even still there of course....

[NO LONGER POSTING]

On face value the gfs looks poor, but run after run what I can see is cold air constantly cutting in behind any lows that track further north so snow in northern parts and further south at times. 

With the lows that look to track further south its a case of pulling up lots of warm air as usual.. 

but this is not set in stone the gfs keeps the south east in the freezer till Thursday next week earliest, that would be a nearly 2 week cold spell for me, which is remarkable!!!! - 7 here this morning.. 

[Ali1977]

A few days of poor charts for oldies but I expect we'll see a flip in FI over the next few days to something much more blocky!! Apart from that not much on the horizon , but enjoyed some pretty hard frosts and sun so not all bad.

[IDO]

9 hours ago, Singularity said:

Well ECM has raised a lot of questions regarding how fast the low cuts off to the SW Thi-Fri or if it even does at all.

In not doing so but retaining a negative tilt ECM appears to keep the Atlantic from fully rolling through until the weekend. Similar to where UKMO appears to be headed, it keeps the south under more HP influence through at least Sat.

Could this proposed wet and wild spell still go the way of other recent ones in 7-10 day modelling i.e. HP manages to hold its ground for the most part across the south? You know what, it wouldn't surprise me!

I really don't get why you would want this pattern to linger? It has given very little in terms of wintry precipitation and promises nothing other than staying colder in the SE. The worst part is that it acts as a block along with the EPO ridge and we end up with the PV tightening up:

ECM D6

With the predicted movement of the main PV lobe towards the NE Canadian region that will surely increase the longevity of any zonal spell. The GFS op now shows no sign of calming even at D16 with a zonal onslaught for 10 days plus. I suspect if that high had pushed east quicker it would have shifted  the pattern and the zonal spell would have been short lived. 

The GFS op looks out of kilter this morning so maybe one to be wary of, otherwise little change from yesterday apart that snow risk for London to D14 is now zero and temps staying milder than average now till D16 at least.

D16 mean:   London ens:

Hopefully there will be a quick response to the strat warming to maybe interfere with the poor trop NH pattern, otherwise we are waiting till mid Feb to see possible changes.

Edited January 22, 2017 by IDO

[Summer Sun]

 

[Polar Maritime]

Many posts have been moved to the Model banter/moan thread so if yours is missing it's in there. Please continue with constructive discussion based on the Model outputs. 

Thanks please continue.

[bluearmy]

Little to be excited about for coldies - the building pattern through week 2  of sceuro block and Atlantic trough is a variation in the overall winter theme. apart from a QTR, the straw to clutch is that the major features would only require a few tweaks to place us in a battle ground type scenario.  not sure where what background driver will encourage those tweaks but I would be looking at potential height rises nw scandi/Svalbard to deflect the Atlantic more se towards Iberia as the place to be looking for hopeful signs. 

[Panayiotis]

1 hour ago, IDO said:

 

With the predicted movement of the main PV lobe towards the NE Canadian region that will surely increase the longevity of any zonal spell. The GFS op now shows no sign of calming even at D16 with a zonal onslaught for 10 days plus. I suspect if that high had pushed east quicker it would have shifted  the pattern and the zonal spell would have been short lived. 

The GFS op looks out of kilter this morning so maybe one to be wary of, otherwise little change from yesterday apart that snow risk for London to D14 is now zero and temps staying milder than average now till D16 at least.

D16 mean: 

Just to add the spread on that D16 mean, which shows almost all of the NH middle latitudes to have some sort of uncertainty, 20 dam difference just to the NW of Britain

Edited January 22, 2017 by Panayiotis

[mb018538]

Looking like we're facing a period of zonality now with the vortex shifting to the nw and ramping up the jet. I expect this thread will be very quiet for a while!

[Singularity]

1 hour ago, IDO said:

I really don't get why you would want this pattern to linger?

I haven't said that I do; just that it wouldn't surprise me given the less enthusiastic removal of the ridge by ECM and UKMO.

Frankly I'd enjoy a week or so of often wild weather for a change. Yet I look at the storm track adjusting northward and fear the low sea ice situation may be encouraging yet more high-Arctic storms at the expense of much action down here in England (Scotland should still be close enough for some action). 

A glimmer of hope comes from the MJO mean projections drifting closer to phase 3 which suggests more chance of a bit of forcing to encourage the jet to head south in our vicinity. Not sure though if it will be enough to overcome the apparent poleward enticement that keeps occurring this winter - perhaps it'll balance out to a mean jet position near central U.K.

 

Better news can be found longer-term IF you don't mind a lingering winter; GFS has reverted to maintaining or even increasing the vortex displacement in the 10-16 day range. Still a chance it could be shoved right down into W. Eurasia rather than just inland of the coast which would greatly improve the prospective impacts to the weather patterns mid-late Feb... again, if you don't mind it staying cold - most troublesome for those in the far south where the sun becomes an increasingly big issue during that period for any lying snow.

[bluearmy]

55 minutes ago, Panayiotis said:

Just to add the spread on that D16 mean, which shows almost all of the NH middle latitudes to have some sort of uncertainty, 20 dam difference just to the NW of Britain

But the lack of spread to our se across most of Europe is the concern 

[Ali1977]

8 minutes ago, bluearmy said:

But the lack of spread to our se across most of Europe is the concern 

Yeah to me this looks like a Euro high is pretty nailed on for the foreseeable !! And low pressure around Northern Greenland!! 

Jet digging further south at 144 on this run, hopefully this puts some pressure on the Euro high (wrong further North)

Edited January 22, 2017 by Ali1977

[Johnp]

1 hour ago, bluearmy said:

Little to be excited about for coldies - the building pattern through week 2  of sceuro block and Atlantic trough is a variation in the overall winter theme. apart from a QTR, the straw to clutch is that the major features would only require a few tweaks to place us in a battle ground type scenario.  not sure where what background driver will encourage those tweaks but I would be looking at potential height rises nw scandi/Svalbard to deflect the Atlantic more se towards Iberia as the place to be looking for hopeful signs. 

What on earth is a QTR?

Not another acronym, I can't keep up.