Model Output Discussion - Into 2024

[JimBob]

2 minutes ago, MJB said:

It's clearly suggesting a battleground scenario, how far north wouldn't be determined until 24/36 hours before. That's if any fronts ever get that far into the UK from the S or SW 

Agreed, probably Midlands north would be the hotspot as the milder weather is never too far away from the South from next weekend onwards. 

[bluearmy]

I’ve been wondering about a height rise or wedge over w scandi if we do see an Atlantic trough extension headed into the e Atlantic. In association with that drift on the tpv to the Canadian side 

[Lukesluckybunch]

Morning guys..I'm sure many of you are pleased with that gfs run..almost the mean now looking pretty awsome!

[Neilsouth]

How things have changed, as I said before a week ago people were forecasting very little in the way of snow, if at all! Air was too dry etc

Yet here we are!

 

 

[nick sussex]

Just now, Neilsouth said:

How things have changed, as I said before a week ago people were forecasting very little in the way of snow, if at all! Air was too dry etc

Yet here we are!

 

 

It’s really thanks to the depth of cold . At the moment it looks like we’ve squeezed out the most possible from that cold pool . Now a wait and see . 

There isn’t a lot of instability but quite a large temp differential between the 850s and sea temps will help .

 

[North Easterly Breeze]

Icon now goes -13s tomorrow afternoon clipping Essex/Kent. 

[ItNeverSnowsInWindsor]

7 minutes ago, Neilsouth said:

How things have changed, as I said before a week ago people were forecasting very little in the way of snow, if at all! Air was too dry etc

Yet here we are!

 

 

Thats nothing to get excited about!

[Duane S.]

43 minutes ago, Richard Fisher said:

Many in here saying a dry outlook but wasn't there lows to our SW next weekend which could lead to a snow event as per Met Office update. Have I missed something? Have these lows now disappeared?

No, this hasn’t all gone. Bar some more progressive runs that were showing it early weekend, any interaction has generally been modelled late weekend / early the following week.

This is subject to big changes yet, because of its interaction with the jet. At the moment the models are clearly struggling with this. There are several options on the table, and will be for a while yet. Some good, some bad, some indifferent.

[nick sussex]

The UKMO fax chart for tomorrow at 6 am shows a convergence zone over the far se . 

This is the likely reason for the warning as this will help convection .

[TSNWK]

2 minutes ago, nick sussex said:

The UKMO fax chart for tomorrow at 6 am shows a convergence zone over the far se . 

This is the likely reason for the warning as this will help convection .

The twig! Could be some surprises with that.. reckon will get sub zero whole time we under -9 850s away from coast.. so a cm or two  decent shout 

Edited January 7 by TSNWK

[tight isobar]

1 minute ago, nick sussex said:

The UKMO fax chart for tomorrow at 6 am shows a convergence zone over the far se . 

This is the likely reason for the warning as this will help convection .

Indeed. This 1 ‘could’- turn into a ripe convection/ streamer banger!!- or just a non effective shower activity zone!! 

[LetItSnow!]

5 minutes ago, prolongedSnowLover said:

Thats nothing to get excited about!

Well if you can't celebrate a little dusting  Take what you can get nowadays, sadly... Better than mid-December, that's for sure!

[LetItSnow!]

7 minutes ago, North Easterly Breeze said:

Icon now goes -13s tomorrow afternoon clipping Essex/Kent. 

Genuine question which will probably show my lack of knowledge compared to some of you but seeing as we have uppers in the range of -10C to -13C  across the south-east then why are projected maximum temperatures still about 4C or 5C? Is this a case of the models overcooking the temperatures and we'll see some surprise ice days in parts or is this moderation from warmer than average seas? 

Regardless, a good week of frosts under high pressure means if we do get the -10C line from a northerly around the 15th then it will pack an extra punch and more solid chance of ice days then I suppose.

[The Northern Ramper]

1 hour ago, Penrith Snow said:

"Houston we have a problem"

You don't have to be a depressed pessimist to see things are trending the wrong way, the ENS are underwhelming and the ECM op a shadow of what was promised a few days ago.

Polish it as much as you want but you won't make the models shine, yes still plenty of time for upgrades as the cold spell is still a week away but we need to see the trend reverse soon.

If it is to go TU then I would rather it be now than at +72 which has happened in the past.

People look at upstream developments in the Pacific but for me it's Iberian Heights that's the issue,  the drought in Spain is now serious and unprecedented with little sign of a change anytime soon.

Andy

When we have had ‘Holy grail’ Synoptics there is only one way it can trend. I mean we had a Polar Low over us the other night.

Things are still looking good to me.

[Mark wheeler]

9 minutes ago, prolongedSnowLover said:

Thats nothing to get excited about!

If I see 20 flakes of snow I will be deliriously happy. For a minute anyway , I could say I was there in the blizzard of 2024 . I might be slightly exaggerating.

[Methuselah]

If the GFS 06Z is right, , days 8, 9 and 10 might be rather nippy?  After that, it's anyone's guess!

[Ali1977]

If we are to see upgrades in the models this afternoon look out for the METO update, we need that to stick firm !! The models we see are all suggesting the block to fail quite quickly after the cold hits the U.K. next weekend (GEM ENS maybe otherwise) - the METO update currently suggest otherwise so I’m hoping their computers go against the ECM etc…

[Kentspur]

2 hours ago, E17boy said:

Morning all

Very good point from catacol . I think what it is that because we have experienced the severe cold of 2010 and 2018 that has been laid as a reaching point in order to match these years.  However like we saw last December it does not have to go to that extreme for us here to get a good snow cover. Here in NE London where I am last year the evening of December 11th brought a fair amount of snow to the SE from a feature that came from the channel. That snow then laid for the next 5 days and the cold at that time was not as cold as 2010 or 2018. So with the models showing a cold or at times very cold theme in the days to come is a good start.

Anyway having said the above I know a lot of people are concerned about the amount of snow in the setup. Yes a lot of dry weather is on the cards but as many have said features will appear and there will be surprises. 
 

I myself am now looking and very much hoping that we get this high to move to Scandinavia that will help open doors to tap in to some cold from the east or north east hence allowing a better chance of snow. I have got my fingers crossed for this so let’s see how the next days pan out. 
 

Taking all the above still early days so as always caution is not not forgotten.

ARE WE GETTING CLOSER IN FINDING OUR WINTER WONDERLAND 

have a nice Sunday all

regards.

Remember that well like many other falls for London and north of the M4 did ok but here was rain and sleet this event should provide more for those south of the Thames thankfully although Im not hopeful on settling snow right by the Thames where I am despite this the Met warning areas over the Downs mainly

Edited January 7 by Kentspur

[bluearmy]

7 minutes ago, LetItSnow! said:

Genuine question which will probably show my lack of knowledge compared to some of you but seeing as we have uppers in the range of -10C to -13C  across the south-east then why are projected maximum temperatures still about 4C or 5C? Is this a case of the models overcooking the temperatures and we'll see some surprise ice days in parts or is this moderation from warmer than average seas? 

Regardless, a good week of frosts under high pressure means if we do get the -10C line from a northerly around the 15th then it will pack an extra punch and more solid chance of ice days then I suppose.

Suppose it depends how cold it gets overnight 

if there’s a stiff breeze and it’s cloudy then temps will struggle to get too low and tomorrow they’ll eek their way up in the cloud to very low single figures away from coastal counties where the onshore flow will keep them a little higher.  Certainly think an ice day is more than likely in the grey area away from the stiffest breeze or the brightest  area where we might see overnight mins getting down to -3/-4 in prone spots 

[nick sussex]

Interestingly the UKMO warning is for 4 am to 10 am and that’s before the coldest 850s arrive .

At that point it will be a case of seeing how much convection can happen without the help of the convergence zone .

Certainly I think it’s best to keep expectations low and then just see what happens .

[jmp223]

10 minutes ago, LetItSnow! said:

Genuine question which will probably show my lack of knowledge compared to some of you but seeing as we have uppers in the range of -10C to -13C  across the south-east then why are projected maximum temperatures still about 4C or 5C? Is this a case of the models overcooking the temperatures and we'll see some surprise ice days in parts or is this moderation from warmer than average seas? 

Regardless, a good week of frosts under high pressure means if we do get the -10C line from a northerly around the 15th then it will pack an extra punch and more solid chance of ice days then I suppose.

ATMO 203 Tutorials - The 850 mb Forecasting Technique

SITES.GOOGLE.COM

---

During the day, convective mixing dominates. The ground heats the air from below; as the air warms, it bubbles upward and is replaced by cooler air from above. The cycle continues...

 

This should help

[Battleground Snow]

50 minutes ago, sheikhy said:

@Battleground Snow

ECM still adjusting now with the cold pool, poor performance over last 3 days.... Was always the furthest south of every model

Edited January 7 by Battleground Snow

[Metwatch]

2 hours ago, Catacol said:

850s of -12 = Severe Cold (very rare in truth, if you want lots of these go to Canada!)

Just about getting into that severe cold airmass territory tomorrow with 850s of around -12C modelled by the UKV 03z in the south!

If only the high pressure was further north and lower heights, we would get something closer to the likes of mid March 2018, A lot of North Sea shower activity that weekend.

 

However I think the south east could get a few surprises tomorrow, with a convergence line shown on the Met Office Fax now.

Edited January 7 by Metwatch

[Tamara]

Posted extract from 30 December:

If we were to take a diagnostic template of GWO Phase 4 (and account for a likely return shallow orbit through phases 0,8 & back to 4) during an intermediate 'lull', then that very intermediate lull phase you describe will likely feature the return of a flat upper flow extending towards Europe.

The difference to recently though with the Atlantic forcing will be the jet suppressed further south - and with a cold pool established then attritional forcing of lows against the blocking likely to be a feature. (This accounts for some of the thinking as expressed within my previous posts in respect of the sub tropical jet)

With a cold pool established, any erosion from the south/west into NW Europe is likely to be attritional and not likely to displace cold pooling totally.

Taking into account we are still now in the lag period for the effect of +ve momentum from FT/MT mechanisms c/o the recent tropical>extra tropical cycle, we are seeing the new convective signal come into the Indian Ocean. Sea temp anomalies are supportive of deep thunderstorm convection. This, allied to convection in the western Pacific, will generate further mean zonal west wind anomalies to propagate across the tropics into the sub-tropics. With the westerly wind additions generated in December still in the atmospheric circulation, total and relative angular momentum will increase sending the GWO back into a (potential high amplitude) phase 5 orbit.

This progression & evolution suggests a strong -ve NAO with positive height anomalies shuffling between Greenland > Iceland and Scandinavia. Meantime southern Europe wet & mild under the sub tropical jetstream

................................................................................................

 Cutting through the frenzy of  intense reactive posting to NWP output, next to nothing has changed in the suggested outlook since this summary last weekend.

In simple terms, NWP is teeing up the scenario of cold arctic air coming south through N Europe at the same time as momentum starts to return from the west c/o the sub tropical jet stream from next weekend. Based purely on attempted objectivity and looking at probabilistic solutions, rather than being wired to a desired outcome, the bold captions in the posted extract hold very true.

This macro scale diagnostic is not a substitute for micro scale pinning down of thermal boundaries across a given part of the UK or any locality elsewhere in NW Europe, but clearly quite an envelope exists in respect of potential high impact winter weather outcomes where precisely this boundary sets up. For my own part of SW Europe, once the chilly static pattern of the coming week is dislodged from the end of the week, the envelope of probability is smaller in respect of the warmer moister sub tropical jet flow well south of the likely thermal boundary. That will be much welcomed in respect of turning down heating and removing the need for protecting tender plants & farm produce from any night time frosts.

Longer term NWP means are next to worthless in the present scenario - the attritional boundary of the dense cold air advecting south and where it sets up against the returning jet stream cannot be pinned down at this stage and there is so much "noise" within the envelope that nothing can be discerned from such a wide blend.. But quite likely that any returning axis of vorticity to the Canadian side of the arctic will engage the sub tropical jet in such a way as to create an easterly vector above where the polar front eventually lies, and this as such define the high impact weather zone in itself. In this way, it might be worth watching how pressure orientates itself to the NE at such a time. But that is where a next updated analysis may be prescient.

At times like these with seemingly complex factors at play, it helps to return to previous analysis and have confirmation that the main ingredients are panning out as anticipated.

Boa tarde

[North Easterly Breeze]

Upgrade it looks to me from the ICON, 2-3cm now covering much of the SE quarter.