[South West and Central Southern England Regional Weather Discussion 08 Feb 2021 Onward]

4 hours ago, Dorsetbred said:

Maybe the Weather Gods haven't heard the phrase "New Year resolution" time for a change?

Ha! The forecasting headaches of late certainly haven't changed...(epitomised below)! 

[Model discussion - hunt for cold Christmas period 2021]

10 minutes ago, MJB said:

Ahhhh ok , Thank you Ian 

No worries! I assume the misconception is simply because the primary deterministic global model we use on TV graphics is ECMWF (although we can, & some of us periodically do, also show GFS & UKMO-GM for comparative purposes such as the lead-up saga we endured into Christmas Day). The principal mesoscale/regional model we used was, until a fortnight ago, Euro4 (with its raw output edited as needed by DTN forecast team). However with that model now retiring, we've switched to UKVx as the default. None of this feeds into the app, however - both it, plus TV site max/mins & 7-day outlooks are MOS driven, as prior explained. Cheers

[Model discussion - hunt for cold Christmas period 2021]

1 hour ago, MJB said:

They are indeed BBC goes off the ECM - XC as we know is a GFS follower 

No, it isn't a replication of ECMWF deterministic (a common misconception). The BBC wx app - as with MeteoGroup/DTN's WeatherPro - is fed by DTN's proprietary MOS data, using statistical blend *including* ECMWF output. It can also be tweaked as needed throughout the day by DTN forecasters, who can 'group select' locations in a given area to update their respective site-specific solutions shown in the app (eg based on radar, obs etc).

[Model discussion - hunt for cold Christmas period 2021]

1 minute ago, Tim Bland said:

Hi Ian, thanks for the insight. Wasn’t a dig at the forecaster who writes them,  more a response to ‘winter is over’ posts citing the meto long range as evidence. As you say these are compiled based on the data at the time…and that data / model outputs are liable to change. On our tiny island we are vulnerable to small changes so it’s a difficult task …that’s what makes it so interesting ! 

Hi Tim, yup - absolutely. For those of us who accept the meteorological calendar as a mere statistical construct & instead pay attention to the astronomical version, winter '21-22 is in its mere infancy and where we've ended-up by March is intriguing - if currently imponderable - speculation. On face-value, so many pointers favour a colder outcome (broadly so, especially for parts of Europe but with UK periodically being in-play). However, to what extent that relies on outcome with the stratospheric polar vortex & the degree of offset (to otherwise cold historical analogues) from background climate warming is a learning curve we are now riding-on through the coming weeks!

[Model discussion - hunt for cold Christmas period 2021]

35 minutes ago, Tim Bland said:

How often do you read this?  If you follow it regularly you will know that 2 weeks ago it was describing below average temps and widespread snow and ice for this week.  In fact on Wednesday they were talking about snow for central areas on Christmas Day… truth is they are not very accurate and haven’t  ‘called it right’ very often so far this winter and they could flip to cold and snow again any day

Hi Tim, in all fairness to UKMO these updates you mention are just one of the many forecast duties performed by (I assume still - certainly was, quite recently) a deputy chief forecaster on a busy shift of many pressing tasks, some of greater immediacy. They're predicated on the 2x weekly updates of extended ECMWF output, plus -  when/if relevant - any conflicting strong signal from Glosea6. Thus the continuity of overall emphasis won't necessarily change day-to-day, as that would become an unfathomable mess reacting run-to-run. In similar vein, the BBC Monthly outlook is also tied to ECMWF updates, albeit over many recent weeks they've (DTN) purposely leaned to caution over that model's solution(s) beyond a ~2 week lead due to poor performance, heading instead in favour of statistical models/analogues. So the UKMO longer-lead switches aren't down to forecasters being volatile(!), but instead the modelling. They're compiled in good faith from the available evidence as they see it, in simplified format, very much as are the BBC ones (ie translating into a public-facing style the more 'technical' sub-seasonal forecasts that DTN issue 2x weekly). It can be a poison chalice writing these, especially in winter. Cheers.

[Model discussion - hunt for cold Christmas period 2021]

26 minutes ago, fromey said:

And to rub salt into our wounds!!

Hail, I think from the photos & videos I saw a few days ago of this event. Plus reportedly that camel photo is a prior one from another Middle East location a year or two ago. 

[It's farewell from Michael Fish]

Hi Michael, by the time I joined the BBC Weather fold in 2007 you'd moved-on from WX Centre days (albeit leaving the likes of Rob M, Peter G & a few others to 'carry the flag' from prior halcyon days!). Nonetheless it was always a pleasure to chat with you & hear your sage views on our daily regional UKMO conference calls when you were covering BBC SE at Tunbridge Wells. Like so many others have expressed, you were an inspiration in my younger days - and your memorable broadcasts through some key weather events have become inimitable parts of BBC history.  You have been at the vanguard of UK weather broadcasting and I wish you all the very best for your well-earned retirement. Meanwhile, Merry Christmas & Happy New Year!

[Model discussion - hunt for cold - Christmas countdown]

Just now, Updated_Weather said:

Not very well I believe!

Actually it's an entirely competent mesoscale/European domain model (& indeed proved exceptionally useful on numerous occasions as a forecasting tool during the 2021 Formula One season, for various agencies). Alongside ARPEGE, EURO4 (RIP!) & others, always perused by e.g. UKMO duty Chief Forecaster in overall assessments. Lately we are seeing a repeated saga of various operational models expressing themselves run-to-run across a varied span of respective ensemble envelopes and indeed at longer lead times, not helped by ongoing poor performance of sub-seasonal models particularly beyond ~wk2. And winter (strictly) hasn't even started until tomorrow...

[Netweather Winter Forecast 2021/2022]

Interesting read Nick, and in many respects is replicating the thoughts of DTN/WCS, whose winter outlook discussion (with associated statistical modelling/analogues) was issued a week ago & discussed with their extended forecasting folk in a subsequent conference call. Like you, they stress how the colder risks post mid-Jan & especially into Feb are highly predicated on SPV outcome by/into that period - an imponderable (despite the strong analogue support, as you note) that simply won't be adequately resolved in seasonal models. However as DTN (& you) also stress, even a close analogue match to certain historical cold winters & associated key forcings (eg 1962) is no longer a viable direct parallel, especially re potency of cold etc., given the more recent backdrop of climate trends. It's certainly a fascinating winter ahead and not least, as WCS point-out, in assessing performance of the longer-lead dynamical models (including at sub-seasonal range) versus statistical & analogue assessment. Jury out! Cheers. 

[Autumn 2021 - Moans, Ramps & Chat]

1 hour ago, shawty1984 said:

Is it just me or are people getting overly excited in the mod thread, posting pics of how many cm's the country will have? Some of the pics are basically showing snow over the hills and basically nothing for low land or just a cm, which will amount to nothing. 

Detail tbc re scope of lowland snow potential in parts of south at least, but in broadest terms the cautionary point (& this is an annual one made by many of us on eg Twitter) is how eg ECMWF accumulates *all* solid ppn, ie sleet too; plus accumulation fields won't adequately represent depth temps (thus actual tendency of snow to genuinely accumulate on ground or not). What's seen falling from sky, as opposed to actually lying on ground (other than fleetingly), won't necessarily be adequately represented yet in model fields for lower elevations at least. 

[Autumn 2021 - Moans, Ramps & Chat]

16 minutes ago, Frostbite1980 said:

So thus is very conflicting then considering the Met are going for an above average winter with any cold reserved for November/December. Thank you for putting me straight though

Yes, albeit I don't see this as some competition: it merely manifests an interesting dichotomy (but with some common threads) between the differing scientific approach of the two organisations. Also bear in mind that UKMO Seasonal Team will issue their 3-month update shortly for contingency planners; similarly DTN issue customers their updated UK prognosis for the D-J-F period imminently (this week). Those will of course assimilate factors that may have differed in outlooks prepared a month ago (eg ref scope of La Nina; SPV forecasts etc). How much overall faith is placed in latest suite of seasonal models from the main forecast centres is another matter, too. Cheers.

[Autumn 2021 - Moans, Ramps & Chat]

3 hours ago, Frostbite1980 said:

Interesting read but energy firms will still take their guidance from the Met rather than the DTN.

Not true - much as they do with Highways, DTN has various customers in the energy sector, including National Grid, and have forecast teams dedicated specifically to that industry.  Latest DTN/WCS assessment for European-wide winter (published last week), with statistical analogues that also factor-in the currently strong stratospheric polar vortex, lean to temperatures being rather variable across Europe during the first half of the winter season, followed by growing potential for periods of high latitude blocking during 2nd half (sustained blocking considered rather unlikely until after mid-Jan); with Feb seeing strongest signal.  Cheers. 

[Model output discussion - 5th December 2016 - Into Winter we go]

3 minutes ago, Banbury said:

Shame your posts cant be locked ...............one liners will still be appreciated though

 

It's specifically re modified fields. Not forecast rationale (we communicate that publically already). Cheers.

[Model output discussion - 5th December 2016 - Into Winter we go]

1 minute ago, Nick L said:

To be fair Ian, I am sure this forum gets far more hits than a Facebook weather group. Just something to perhaps consider in future.

I know: but it's moderated etc. Facebook isn't. 

[Model output discussion - 5th December 2016 - Into Winter we go]

4 minutes ago, johnholmes said:

I suspect it was the chart he posted and it then being posted on to Facebook, copyright infringements with UK Met I expect, although Ian is the one to give the actual reason.

The licensing agreement with UKMO, negotiated a few years ago, is for sharing selected items that help offer technical context to forecasts, but social media growth means a risk of items disseminated without permission or proper context and thus possibly not in spirit of original forecast thinking. For now, I'm afraid that means no further sharing of that material aside from more limited ones through twitter, given sensitivities. Back to model discussion.

[Model output discussion - 5th December 2016 - Into Winter we go]

6 minutes ago, blizzard81 said:

Does anybody know what Fergie posted this morning?

Sorry - apparently it was copied to a Facebook group without permission. We had this issue a year or two ago. Thus removed to prevent further reproduction with risk of changed context. 

[Model output discussion - 5th December 2016 - Into Winter we go]

1 minute ago, Nick F said:

That old chestnut comes round every year! Was waiting for someone to mention that.

A lot of the data, probably much of that used by NWP, is derived from satellites as far as I'm aware, also automated weather stations and from aeroplanes and ships play a crucial role if less in number. So can't see how there would be much less data over Christmas as satellite data makes up the majority of data.

Snap! Agreed Nick. It's clearly some modern mythology.

[Model output discussion - 5th December 2016 - Into Winter we go]

Just now, bluearmy said:

If the output was consistent since Xmas eve then you might be able to understand that debate but given the swings in the patterns, run to run in the mid range, I can't see the relevance. 

Meteorological trade runs 24-7 even over Christmas(!); the satellite data keeps churning; many aircraft providing data... etc. I've never heard such a 'theory' espoused anywhere before.

[Model output discussion - 5th December 2016 - Into Winter we go]

12 minutes ago, Changing Skies said:

I'm quite aware of that.

It just seems ECM/GFS have backed off, it's quite odd since the EPS and gefs 0z mean was very decent & consistent now we're seeing consistency with unsavoury output...

nothing's assured yet it must be stressed

What's unsavoury? 18z GFS offers one heck of a chilly block. And effectively dry. Bear in mind 850hPa temps unrepresentative of surface temps in those set-ups (subsidence inversion/continued radiative cooling). Fog could be a real issue however, especially if there's any longevity of continental slack flow and resultant import of higher aerosol levels.

NB Note v different sense of direction further into 12z GFS PARA. Fine balance... etc. 

[Model output discussion - 5th December 2016 - Into Winter we go]

5 minutes ago, Steve Murr said:

It just felt a bit to much swing away from the 00z & the means of the GFS..

18z has moved more towards the ECM with not enough retrograde so overnights will be interesting- but yes for day 6 onwards to about day 10 the locale of high pressure probably wont make to much difference other than frost locale around the coastlines...

lets see what tomorrow brings...

By T+192, 23 members support the flatter solution; 15 centre the high effectively over the UK; and 13 offer a more amplified solution with high pressure to the NW and a markedly colder NE'ly flow. 

[Model output discussion - 5th December 2016 - Into Winter we go]

2 minutes ago, Steve Murr said:

Not the temps - the way the high slips SE @192-216 just feels a tad to far- GFS looks more plausable inline with the -PNA pattern you cited earlier...

See edit above Steve (NB doesn't alter median temps - remaining below avg)

[Model output discussion - 5th December 2016 - Into Winter we go]

23 minutes ago, Steve Murr said:

I think at this stage I would tend to discount the ECM- ( past 192 ) as it does has it moments-

GFS out to 108 - is another step of amplification - so thats 00z > 06z > 12z >18z all making pidgeon steps NW which is good-

hopefully the 138 will be like the 144 UKMO - every bit as likely!

But 12z ECMWF DET sits well in the ensemble spread, with below average temperatures from start of Jan on throughout it's 15d run... why discount it? It's as plausible as any other solution at the moment.

EDIT Whoops sorry, was reverted to 00z ENS - yes, 12z milder end of ENS. 

[Model output discussion - 5th December 2016 - Into Winter we go]

1 hour ago, IDO said:

Hi

I was referring to when it forecasts height rises in the Greenland region, as with the other models, like ECM D10 cross polar flows to GFS Atlantic domination, each model has their foibles, and UKMO, based on my experience blows up the heights in that region.

We shall see how it unfolds. ECMWF Monthly also raises +ve MSLP/GPH anomaly to NW (S of Greenland) into week 2; interestingly it supports GloSea5 on broad idea of a colder than average spell much/most of Jan, with varying NW/N/NE flow (perhaps E'ly later in month); even by week 4 with unusually prominent -ve temp anomalies for southern UK (given the lead time). One way or another, model output looks an awful lot more interesting versus this time a week ago. 

[Model output discussion - 5th December 2016 - Into Winter we go]

PS What is worth noting re UKMO is that the GM isn't modified at Ops Centre beyond T+132. That's considered a reasonable cut-off point for fair medium range steer, in terms of tweaking additional fields such as frontal positions/shortwave elements & associated upper forcing/ppn/cloud cover/ etc.

[Model output discussion - 5th December 2016 - Into Winter we go]

29 minutes ago, Ali1977 said:

The ECM was always going to back track a little as this mornings run was epic and a rare chart, didn't quite expect a big back track and though something akin to the GFS and UKMO but hey ho!! I imagine that the EPS due out at 2030 might give us more of a clue as to this run, lets hope the Op is on the milder and we have a much better cold set, the op this morning was epic but the EPS were nothing special as a whole.

The 12z DET sat comfortably within scope of 00z clusters/ENS. Just one of a few potential outcomes retrospectively but let's see where it sits versus ensembles this time. Where ECMWF monthly heads tonight is of particular interest, given paucity of signals beyond Jan week 1 in last Thursday's outing... Incidentally, someone posted along lines of UKMO-GM being of no credence at T+144, but I've never seen evidence for that published or cited elsewhere.