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Zubzero
06 January 2023 01:22:36

Why do we always get this “x is a write-off” nonsense? Several recent op runs have shown the futility of trying to make a forecast more than a few days in advance yet still people can make guesses in reality pseudo-analysis about the weather nearly 4 weeks in advance. We can say what the weather is currently with very high confidence, what is very likely in the coming days with reasonable confidence and what may be probable in the next ten days or so.

Beyond then any claims of wintry blasts, snowmageddon, blow torches, weeks of zonality etc. are guesswork and should be called such. As this is the model output thread and the only models that go that goes out to the end of Jan are the CFS (no comment) and the ensembles (check out the uncertainties at that time scale) I think it’s safe to ignore such guesses if you are interested in what the models actually show.

What they actually show is a train of unsettled conditions (notably mild initially especially in the south) with weather from a westerly quarter, the potential for lots of rain (notably) in western parts and potentially damaging winds but massive uncertainty in the specific details. What they do not show is that it is safe to write of January whatever that means. And no Sean there is no SSW likely in the immediate future as far as I can see and any PV displacement lies in the realms of FI and guesswork too.

Originally Posted by: doctormog 



It's done to get a reaction and sadly it works most of the time. Anyone who proclaims to know the outlook post 7-10 days for the UK even in a zonal period is not worth listening to, plus you will note the forecasts are rarely backed up with evidence and they dissappear when the we enter a colder spell, then reappear when it ends. If only the weather was as easy to predict as their posting pattern is. 
 
CreweCold
06 January 2023 02:19:03

It's done to get a reaction and sadly it works most of the time. Anyone who proclaims to know the outlook post 7-10 days for the UK even in a zonal period is not worth listening to, plus you will note the forecasts are rarely backed up with evidence and they dissappear when the we enter a colder spell, then reappear when it ends. If only the weather was as easy to predict as their posting pattern is. 
 

Originally Posted by: Zubzero 



That's really not true though.

Zonality (for an extended period) is easy to forecast in winter, purely because to get high latitude blocking you need certain background conditions to produce the required amplification to ultimately displace cold air southwards. This doesn't happen by magic. High pressure doesn't just appear over Greenland or Scandinavia by chance; you can often trace the initial amplification right back to the Pacific.

That's why the December cold spell was so easy to forecast- we saw repeated amplified waves working around the hemisphere which ultimately led to a buckled jet stream and allowed pressure to rise to our east.

We have none of that now...the November pattern waned a long time ago and angular momentum fell away, taking the amplification with it. Ergo, other than brief colder shots spilling south (due to the jet being pushed further south at times), there is no mechanism other than a SSW that will bring us out of this zonal period for the foreseeable. This being said, a weakly amplified passage through MJO phases 6,7,8 may give rise to a drier pattern (mid latitude block) in two week's time or so. You can write off any sustained wintry weather in the next 2 weeks though at least. 

Crewe, Cheshire
55 metres above sea level
+1
Zubzero
06 January 2023 03:27:35

That's really not true though.

Zonality (for an extended period) is easy to forecast in winter, purely because to get high latitude blocking you need certain background conditions to produce the required amplification to ultimately displace cold air southwards. This doesn't happen by magic. High pressure doesn't just appear over Greenland or Scandinavia by chance; you can often trace the initial amplification right back to the Pacific.

That's why the December cold spell was so easy to forecast- we saw repeated amplified waves working around the hemisphere which ultimately led to a buckled jet stream and allowed pressure to rise to our east.

We have none of that now...the November pattern waned a long time ago and angular momentum fell away, taking the amplification with it. Ergo, other than brief colder shots spilling south (due to the jet being pushed further south at times), there is no mechanism other than a SSW that will bring us out of this zonal period for the foreseeable. This being said, a weakly amplified passage through MJO phases 6,7,8 may give rise to a drier pattern (mid latitude block) in two week's time or so. You can write off any sustained wintry weather in the next 2 weeks though at least. 

Originally Posted by: CreweCold 



I Don't remember you or anyone  forecasting a week of Ice days from the cold spell In  December weeks before it occurred?? 

if you could forecast with the accuracy you proclaim you would be a billionaire. Your method may work for the northen hemisphere on a whole but the UK is such a small area and the positioning of where the genral pattern  sets up can have a significant impact on the weather we get. 
it's all most impossible to forecast over 50% accuracy +7-10 range overtime if you could I'd recommend providing your services as it would make you a very rich person. 
CreweCold
06 January 2023 04:46:11

I Don't remember you or anyone  forecasting a week of Ice days from the cold spell In  December weeks before it occurred?? 

if you could forecast with the accuracy you proclaim you would be a billionaire. Your method may work for the northen hemisphere on a whole but the UK is such a small area and the positioning of where the genral pattern  sets up can have a significant impact on the weather we get. 
it's all most impossible to forecast over 50% accuracy +7-10 range overtime if you could I'd recommend providing your services as it would make you a very rich person. 

Originally Posted by: Zubzero 



I did, just not on here.

This was posted at the end of October over on the other forum-

Posted October 25, 2022 
Very encouraging GFS at D8 for the longer term.
As I point out every year, troughing struggling to get past the meridian is what you want to see as you enter November. Nov 2009 featured this in abundance. To my eyes it looks as though the strat is going to be roughed up slightly over the next couple of weeks.
This is a prelude to a pattern change as we go further into Nov and Dec.
A period of meridional jet stream across the Atlantic looks odds on to me latter Nov/into December. The seasonals concur with this too, which is good.

The December spell was very well signposted...

In order to understand what is going on hemispherically and where it is most likely to lead to going forward, you have to have a sound grasp on both the drivers and also be able to analyse the current state of what is going on through NWP in real time. A lot of people cannot do this. So, whilst there is an element of chaos within the umbrella of longer range forecasting, there is also a probabilities game which can be incorporated by implementing the above.

Once you go zonal in the heart of winter (as we are now) it 90% of the time takes a major shake up to get us out of it. This could be via a highly amplified passage through the correct phases of the MJO and increased angular momentum or via wave breaking which leads to a SSW. None of these look likely in the near future, hence we are likely to remain changeable and mild on average.

I'll also add that most people don't realise just how close we were to something very spectacular and long lasting. We needed to keep the amplified wave train going for maybe another week or so in order for a feedback to be initiated i.e continued pressure exerted on the stratosphere from the trop pattern below (the trop was leading the dance). Had we maintained the amplification then, IMO, we'd have been home and dry...the strat would have been out of the game and the trop would have continued to lead the dance throughout January. We just needed the Pacific to play ball for a little while longer. The models toyed with it...




 

Crewe, Cheshire
55 metres above sea level
+2
Brian Gaze
06 January 2023 08:04:23
More of the same probably sums it up this morning.

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Brian Gaze
Berkhamsted
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DEW
  • DEW
  • Advanced Member
06 January 2023 08:05:36
I'm less ambitious - the next week is good and any successful predictions for the week after are a bonus. On which topic ...

WX temp chart - the solid mass of very cold air over Russia in week 1, having failed to make much impression on W Europe breaks up and withdraws E-wards in week 2, with the 0C isotherm running more or less due N-S from Ukraine to Scandinavia, If anything, some milder air works up the W coast of France towards Britain. Rain/pptn sticking with Atlantic coasts, heavy for all of Britain in week 1, pulling back somewhat to the NW in week 2.

GFS Op - a generally zonal W-ly flow across Britain and deflected well to the N as it continues E-wards by a persistent block over S Russia. W-lies augmented by passing LPs 955mb Sun 8th Hebrides, 955mb Wed 11th Rockall, 965mb Thu 19th S Iceland.

ECM similar and throws in an extra LP Sun 15th 980mb N Ireland

GEFS - temps generally near seasonal norm (possible short bursts of mild, now, Wed 11th, Sun 15th, cooler between) and rain at most times in most ens members, least in NE esp at first, most in W
 
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Chichester 12m asl
+2
moomin75
06 January 2023 09:10:20

It's all for show, its all for attention. Mooms as much as we love him has a personality trait that means he simply cannot help himself. This is the same Mooms that time and time again will post a CET prediction at the top or bottom of the pile. In other words 'look at me'. Mooms may be writing off the entire month of January but remember this is the same Mooms that predicted CET of just 2.2c at a time in late December when it looked mild for the first half of the January..... Just saying.

Originally Posted by: Gusty 

​​​​​Yep, I went for a cold CET for January as at the time, I felt that an SSW would come into play for January, but that is looking much less likely now.

If we do get an SSW, it will not probably affect January now, but February, so I feel it's a safe bet to write off this month now.

If/when I'm wrong and the 2nd half if January turns cold, I will take all the hammerings that come my way.

But I don't think January will deliver now.
I am entitled to my opinion, just as I am entitled to change my opinion when viewing the models.   
Witney, Oxfordshire
100m ASL
Brian Gaze
06 January 2023 09:48:15
ECM rolling out a 101 ensemble illustration this morning. Close to perfect.

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Brian Gaze
Berkhamsted
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idj20
06 January 2023 10:19:37
I've just this minute got my usual end-of-week farmers-forecast in the can ready for showing on Facebook later on in the day and I actually felt depressed when I typed it. That said, it looks all typical fare for our mid-latitude climate with nothing too drastic as things stand (nothing like the horrendous "Winter" of 2014). 
Folkestone Harbour. 
Taylor1740
06 January 2023 10:47:09

More of the same probably sums it up this morning.

UserPostedImage

Originally Posted by: Brian Gaze 


so basically the most zonal bog standard typical pattern you could get locked in for most of the remainder of the month?
NW Leeds - 150m amsl
Brian Gaze
06 January 2023 10:48:45

so basically the most zonal bog standard typical pattern you could get locked in for most of the remainder of the month?

Originally Posted by: Taylor1740 



January increasingly seems to be all bark and no bite.
Brian Gaze
Berkhamsted
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+1
doctormog
06 January 2023 10:57:55

January increasingly seems to be all bark and no bite.

Originally Posted by: Brian Gaze 



There’s not been much bark evident either so far!
Aberdeen
Current conditions (personal WS) 
The Beast from the East
06 January 2023 11:13:06
GFS 06z a horror show from start to finish
 
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Rob K
06 January 2023 11:26:55

More of the same probably sums it up this morning.

UserPostedImage

Originally Posted by: Brian Gaze 



More of the same although the jet seems to be sinking ever further south through the run giving the possibility of snow increasingly far south by the end of the run. I suspect it is GFS being overkeen on playing up the snow risk, as snow in the south is extremely rare from a westerly set-up, but you never know.
Yateley, NE Hampshire, 73m asl
"But who wants to be foretold the weather? It is bad enough when it comes, without our having the misery of knowing about it beforehand." — Jerome K. Jerome
fairweather
06 January 2023 11:39:21
When was the last cold January? December and March seem favourites in recent decades. Never happens during the coldest part of winter.
S.Essex, 42m ASL
warrenb
06 January 2023 11:56:49
Can we all stop about it is going to be mild, the ENS point to average, and it is called average for a reason. It isn't mild and it isn't cold, it is average.
Tonbridge 45m 
Brian Gaze
06 January 2023 12:02:57

Can we all stop about it is going to be mild, the ENS point to average, and it is called average for a reason. It isn't mild and it isn't cold, it is average.

Originally Posted by: warrenb 



I'm not convinced by that, at least in the southern half of the UK. My guess is that temps over the next couple of weeks when aggregated will be above the average. 
Brian Gaze
Berkhamsted
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"I'm not socialist, I know that. I don't believe in sharing my money." - Gary Numan
doctormog
06 January 2023 12:04:25

When was the last cold January? December and March seem favourites in recent decades. Never happens during the coldest part of winter.

Originally Posted by: fairweather 



2021?
Aberdeen
Current conditions (personal WS) 
Saint Snow
06 January 2023 12:08:45

Can we all stop about it is going to be mild, the ENS point to average, and it is called average for a reason. It isn't mild and it isn't cold, it is average.

Originally Posted by: warrenb 




Average is mild 😋

Martin
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idj20
06 January 2023 12:28:00
The GFS 06z control run keeps hopes of a drier and settled set up by the end of this month alive. 😂
Folkestone Harbour. 
Taylor1740
06 January 2023 12:28:36

Can we all stop about it is going to be mild, the ENS point to average, and it is called average for a reason. It isn't mild and it isn't cold, it is average.

Originally Posted by: warrenb 


Average in regards to upper air temperatures perhaps but the lack of cold nights and frosts means it will likely still be above average in regards to mean temperatures over a 24 hour period.
NW Leeds - 150m amsl
ballamar
06 January 2023 12:33:43
GEFS give a typical pattern of lows moving through mild followed by chilly nothing long lasting or too extreme. As in the setup the further north the better chance of wintry precipitation. At the moment looks like a couple of weeks of this pattern. Could be the odd surprise!
Brian Gaze
06 January 2023 12:36:29

Average in regards to upper air temperatures perhaps but the lack of cold nights and frosts means it will likely still be above average in regards to mean temperatures over a 24 hour period.

Originally Posted by: Taylor1740 



Indeed, but even the daytime temperatures look most likely to be above the average, at least in the south.

https://www.theweatheroutlook.com/premium/gefs-tables.aspx?run=12&fv=tmp2max&loc=london&lat=51.5&lon=0&p=&cty= 
 
Brian Gaze
Berkhamsted
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"I'm not socialist, I know that. I don't believe in sharing my money." - Gary Numan
Rob K
06 January 2023 12:36:31
The GFS det run shows snow cover for much of the country by the latter stages. As mentioned above I imagine the reality would be cold rain anywhere south of the Midlands and/or at low altitudes - GFS seems not to factor in the UK surface mildness for whatever reason.
Yateley, NE Hampshire, 73m asl
"But who wants to be foretold the weather? It is bad enough when it comes, without our having the misery of knowing about it beforehand." — Jerome K. Jerome
Jiries
06 January 2023 12:53:13

Average in regards to upper air temperatures perhaps but the lack of cold nights and frosts means it will likely still be above average in regards to mean temperatures over a 24 hour period.

Originally Posted by: Taylor1740 



Thank god the mild weather had been a massive blessing to keep the heating costs down as now so far up to 5th Jan my billing is £8 less than last month horror bone dry cold spell, from £26 to £18. If there no snow or real cold in the models then better to stay mild.  My apps show 8 to 12C temps which is above average for here in Jan at 7C.  Daylight also now slowly drawing out. Temps will rise to 11C tonight so another great night for shorter quicker heating up indoors when very mild and cloudy over night.
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