Duane S.

It does looks very wrong. The JMA has this at 10mb. Data input error… It does looks very wrong. The JMA has this at 10mb. Data input error…

The Berlin site certainly seems to be missing somethings. i think they have revamped it, it looks different. Like the U wind charts that includes the Southern Hemisphere now, I’m sure it didn’t before? But most areas are not available at all and a few others that are have aspects missing. Hopefully a Work In Progress that will be complete soon, in time for winter

Great ECM. Not in terms of its on the ground output (certainly not for my area!), but in terms of how far away from yesterday evening’s 12z it is. Nick pointed out the upstream differences. A channel low at this time of year is a very high risk high reward beast with very fine lines of marginality. On the coast we would need to roll a double 6. Plus when the PPN hits (as in, day or night) often becomes more pertinent as well. While there’s hope though.. I’m torn at the moment as to whether we will see our usual southern shift or not though. Extreme retrogression taking the block away from influence is very well backed up and as such will allow the Atlantic in, albeit with a possible second shot at something a bit later. Then again, if the strength of the block has been underestimated, as is often the case, that may be enough. I am currently ( only just) siding on the less favourable former, but at the same time think we could see just about any outcome occur, high entropy.

And it wasn't a flash in the pan either... Huge perturbations likely through next month.

If snow preservation is your primary worry when it comes to a cold snap/spell then you’re getting it all wrong. The best time of year would naturally by around mid December for that, however that’s exactly at the time when the vortex is naturally winding up to dominate, thus exactly when low lying snowfall becomes less likely as a direct result. Expecting optimal Synoptics at the optimal point of winter will lead way more often to disappointment than to joy. We will chase it every year regardless and every so often the stars will align. A bit like the couple on Phil & Kirsty who want the best house, for a cheap price in the right location. Apart from very rarely, it doesn’t happen, and again for obvious reasons. It’s not bad luck or typical UK etc etc that we often see more genuine opportunities at this time of year than back in December. Many years we don’t even get that of course but a snowy cold March looks something that is quite possible this year.

March is an interesting and often underestimated month for snow. Obviously I am talking about for low lying areas of the UK, away from the usual favoured elevated places. The biggest negative probably being that the melt rate will be much higher, as the sun gains strength daily. So long lasting snow cover is unlikely, although it can never be truly ruled out... However, there is a double edged sword here as our enemy the sun can also be our biggest ally. Often providing that extra boost of energy as showers cross land. Add in SSTs being much lower than during the first half of winter, thus March snow should never be downplayed. And I certainly don't agree that we need at least -10 850s to produce either. Far too simplistic an approach.

Yep. In one. Coupled with lag from the recent MJO activity (and potential Pacific MJO enhanced activity later on). I can't imagine the models have got a firm grip on this at all.

To me, the signals are screaming retrogression to Greenland from the rooftops. However, I maintain a West Based NAO has to be a very real outcome thereafter. Not ideal I know but I'd take a couple of really snowy days if that's how things ended up. Remember, down here, our expectation are not the same as most others

One or two still struggling with how much a warming of this magnitude, mixed in with other favourable background signals/forcings, will affect the models, they will struggle. Those poo pooing a cold outcome are on a very sticky wicket in this type of scenario. Us bemoaning a west based NAO will be a much more likely than an average/mild spell as time goes on… Hopefully not, although extreme retrogression has to be a distinct possibility later on. Let’s just hope we pull out a good cold spell over the coming weeks, I’d say we have every chance here. Late Feb/March cold isn’t everyone’s cup of tea but I say bring it on, far far more likely to get snow than in November. I’d rather have the problem of an increased melt rate associated with late winter, than no snow to melt in the low diurnal early winter!

Irrespective of to what degree different people understand charts, teleconnections, background signals etc, the same problem resides in this forum. There are those who only seem to look at charts at face value. i.e... a set of 4 x daily GEFS plot, which are showing nothing particularly spectacular on the horizon. And there are those who are willing to open their minds to what is going on upstream (and up above) and factor in the entropy involved in this. You don't have to be an expert to understand the notion. And right now, we have factors that greatly increase the chances of a cold spell, even severe cold spell come the end of month and through March. The information is all there if you care to take the time, if not, carry on posting your charts but don't expect any kudos to be given when the SSW doesn't produce anything on the ground over the UK. Which of course it may well equally not do so

I've been monitoring the MJO plots over the past 2 weeks and after the GEFS forecast moved edged towards less active yesterday, it has moved back again today to more active. For balance ECM still holding firm in the inactive COD but signs of it becoming more active. Whilst I wouldn't correlate phase #4 / #5 to preferred blocking scenarios in the same way we may 6/7/8 (and also the lag times wouldn't really tie up), I think just having greater amplitude and the pulse heading towards the Pacific may well still be having an effect on the models at D7+. Bear in mind just +1.5 SD is counted as VA (Very Active) and anything above 2.5 SD is counted as EA (Extremely Active). Phases 4 and 5, partially because of the terrain, is notoriously the most difficult to forecast correctly but there seems to be a decent and increasing amount getting deep into the Pacific now at high amplitude. Combine with what is going on >20 km overhead, I really think February and into March could be quite special. COULD be

Usual James Madden garbage. Add in his best chums Piers Corbyn and the 'journalist' Nathan Rao, and you have the 3 main perpetrators of the near weekly nonsense spouted in some of the low brow rags (massive snow bombs, one in a generation snowstorms, apocalyptic storms etc etc) . All he does is follows the models like us, and when there is a chase (which is fairly often let's face it) , just like now, will publish it like it has a 95 % chance of happening. I suppose he will be right about 1 in 20 times but don't let that get in the way of a sensationalist story. Shocking how this is allowed, but hey... That said, I'd love for him to be right this time

This will be interesting. For the past 10 days or so, these 2 have been showing an incredibly consistent different amplitude forecast. With the GEFS consistently more amplified going through the IO, towards the Pacific. No doubt will end up meeting somewhere in the middle, but we will see soon...

Et voila, the 12z ops sniff it. Like I said, this shouldn't come as any surprise.

I think many are under estimated the potential here, (yes that word 'potential', but it is what it is). With a disrupted strat unknown entity factored in .. IMO there is a notable 'tipping point' around D8, a sliding doors moment, call it what you will. The PV will probably overcome the ridging but it is very close to being a very special chart this (my particular interest ringed)... Al I am saying is, unlike most occasions, it wouldn't take much of a tweak for things to take a very different path to what follows on from above on the 06z...

Never take a chart in isolation, but this one raises an eyebrow… And this one most definitely raises both!… That sort of movement upwards at 30mb is often a precursor to much more interesting weather to follow. We will see.

Fabulous snow today at work (just north of Dorchester). It went quickly from bright sun to really dark and then snowed for about 3 hours. Hands down the biggest flakes I've seen for as long as I can remember here.

Decent amplitude there. I tend to find, for wave 2, above 700 down to at least 10mb can start getting interesting. This looks very interesting. Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4791446

Decent amplitude there. I tend to find, for wave 2, above 700 down to at least 10mb can start getting interesting. This looks very interesting.

9 SD ?? I’m sure it’s 6 but even so, that’s impressive.

Indeed. It’s a start

To me, that’s a split. Yes there is a ‘main’ vortex that has essentially been displaced off the pole but high pressure / warming has cut through it enough, that we have a weaker separate low pressure on the other side now.

Charts of the day for me are for what’s going on way above our heads in the stratosphere. As has already been highlighted, we have a strong warming now down to the 10mb level Further up right at the top we can see constant warming right through from now to D16, waxing to very warm and only waning a bit each time before another pulse hits. This is going to cause serious damage and it will as always be a case of how far/fast it propagates downwards. We can see how the SPV at that level is fairly unperturbed by the warming here at D0 Here at just before D5, the warming strengthens and first signs of the top of the vortex getting some pressure on it Go forward just a bit to just past D6 and the warming is really strong now, you can see the vortex getting pushed and starting to become enveloped, which invokes a squeeze. More pressure being applied, in fact it’s pretty relentless. This at just past D8… On to past D12 and the vortex is a shadow of its former self at this level. Weakened and susceptible. And finally after all this pressure we get a split. Bear in mind that this is playing our right at the top of the stratosphere and we will need it to work down to affect our weather and even then, it only increases our chances of a cold spell (assuming it does work down), never guarantees it. And obviously these are just forecasts, but I suspect even a watered down version is going to cause the SPV a lot of unwanted pressure and translate into a very interesting period of chart output over the coming weeks. But it is encouraging to see very decent warming forecast to get down to the the 10mb level and below over time Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4787523

Charts of the day for me are for what’s going on way above our heads in the stratosphere. As has already been highlighted, we have a strong warming now down to the 10mb level Further up right at the top we can see constant warming right through from now to D16, waxing to very warm and only waning a bit each time before another pulse hits. This is going to cause serious damage and it will as always be a case of how far/fast it propagates downwards. We can see how the SPV at that level is fairly unperturbed by the warming here at D0 Here at just before D5, the warming strengthens and first signs of the top of the vortex getting some pressure on it Go forward just a bit to just past D6 and the warming is really strong now, you can see the vortex getting pushed and starting to become enveloped, which invokes a squeeze. More pressure being applied, in fact it’s pretty relentless. This at just past D8… On to past D12 and the vortex is a shadow of its former self at this level. Weakened and susceptible. And finally after all this pressure we get a split. Bear in mind that this is playing our right at the top of the stratosphere and we will need it to work down to affect our weather and even then, it only increases our chances of a cold spell (assuming it does work down), never guarantees it. And obviously these are just forecasts, but I suspect even a watered down version is going to cause the SPV a lot of unwanted pressure and translate into a very interesting period of chart output over the coming weeks. But it is encouraging to see very decent warming forecast to get down to the the 10mb level and below over time

For me it was the subtle persistence of the cross-model ens to show a mini flat line tendency (notwithstanding the sharp spike now showing up), even back over a week ago for this period. This tied in background signals and corresponding lag, and the 17/01 period always seemed a good match for a potential cold snap. For our neck of the woods (this is obviously even more marked further north)...