Duane S.

Putting aside the fact that the warm up supposedly starts from D10+ (proper FI territory), in the far more reliable time-frame that same Op keeps Dorset in sub -5 850s for 9 consecutive days . That is quite something at any point of any winter down here. For the record though, the trend is there and I think there is a fair bit of substance to back up a 'warm up' in about 10 days' time. Thereafter (and assuming it does actually go a lot milder in the first place) it could go either way really.

As others have said, it is the modelling of the block strength (and location) that is fundamentally this difference here and what sets it on a different path to poorer looking runs . We can but hope the the ECM, amongst others, has called it right.

They would potentially dumbbell to some degree

Oh my. Reinforcements arrive for our block and the next low stopped in its tracks way back in the Atlantic. Cold going nowhere. This is one gorgeous chart

ECM stunner this morning. Another comparison with yesterday’s…

Just

Comparison with yesterday looks favourable for us…

Now what’s going on? I go away for 15 minutes and come back to this… Another new direction later on !

Just look at those lovely heights forming above us on this run In theory the latest model run should always be the most accurate. The 18z therefore has got this. No discussion needed

Looks like it’s going to spawn off a secondary low even earlier here?

Icon. Atlantic low pressure holding back slightly further west at D5 A small win

Assuming the 'will likely trend south' mantra, in a reasonably good place right now for 6 days out I'd say. If only it was that straight forward though!

The 18z raises the bar even higher! This could be a memorable month

Totally agree with this. The timing seems almost too perfect for once. Possibly this last thing we want is a big retrograde signal in about a week. Then just when the waning takes place, more forcing looks like it may come to our aid and we wax again. Followed by a wildcard SSW a few weeks on? Getting ahead of myself a bit now

Great runs this morning again Worth remembering the dice analogy at these times. If the atmosphere, backed up by background signals/teleconnections, do NOT have a predisposition to cold, we need to roll a double six. This is one of the rare times when we genuinely have an atmosphere primed for a lengthy cold spell and snow. A double six now gets us nirvana, a 9,10,11 is enough for a memorable spell, 6,7,8 gets us a decent cold spell with snow for some, 3,4,5 gets us a watered down version of what could’ve been and a 1,2 gets us snow on the tops of hills with a quick breakdown. Dice is a good analogy also, because with EVERY incoming cold spell we need a bit of luck as well. And to boot, you’d be a brave person to bet against an SSW (or as near as) taking place by mid January at the latest.

Indeed. The stealthy killer of many a past cold spell is the Low Countries surface high. Need to keep an eye on that and hope low pressure dropping from the NE plays ball. Slack heights are all well and good for frigid cold but a little surface high popping up could be a consequence. Innocuous looking but can be very influential. Here’s hoping it will be more of an Icelandic wedge friendly type

I’m still making my way through, a few pages back, whilst catching up the 12z suite, but I suspect this may been posted already What on EARTH sort of chart is this!??

Just fabulous viewing at the moment. So then, THAT low out towards the Azores…This is proper high risk (extraordinarily) high reward stuff. Classic jackpot scenario for the SW amongst other areas. This system contains tropical air and will be absolutely bursting with moisture. If it were to interact in the right way as it inevitably fills and tracks more E than NE, with an established cold airmass over us, some places could have a once in generational snowfall. The current SSTs will probably make it difficult around the coasts, but my word, there certainly is potential for something very special here.

@Mike Poole on it with that low analysis. It does feel like it could be a bit of a sliding doors moment that, with the 06z showing we don’t want, which allows heights to seep out south eastwards and cut off the flow. We’d then be looking for a round 2 attempt. Subtle differences in how the runs model the jet streak on the other side of the NH, as it buckles and splits. Day 2. 00z and 06z in decent agreement on this… But then, in just T+96… 00z 06z… Fascinating times though! And let’s be real, the 06z in isolation is hardly shabby for the time of year

Simply stunning short - medium term ens for the balmy south coast in December

We have to remember the fine margins involved with cold/snow and our water surrounded isle. It’s always amusing to watch as one poster panic things are going too far NW whilst another is focusing on another chart worrying about it slipping SE . This is no standard toppler situation, thanks to the retrogression in play, for once we aren’t worried about the cold slipping east through the Low Countries and we’re back to mild mush. However a west based NAO is always a possibility. We can’t have it all ways, we won’t ever have that margin of error. Anyway, bottom line, we have a great chance for a proper cold spells, reloads and a memorable winter folks

Indeed. Embedded cold is often overlooked. It creates a feedback loop of sorts, that can mean marginal situations/areas get snow that otherwise would’ve been sleet/rain. And yes, Feb ‘78 is a great example of this. Its not for nothing the saying goes - get the cold in first…

Ridiculous output from the ECM Op One of the best ever probably We have ourselves a proper old school ECM V GFS standoff (with others milling around, unsure where to plant their flags). And it’s hardly as though GFS is all mild and Atlanticy either, so what a way to enter the winter season in a few days time!

It’s difficult to see past how unusual this is. And (whisper it quietly) how good things look for the month of December. Notwithstanding a massive unexpected solar storm ️ (that’s a joke, well, sort of ), it’s equally difficult to see us missing out completely on a cold spell between now and the end of next month. We have an unusual amount of ‘wiggle room’ for a change. So, what do we have? The list of ‘drivers’ below in our favour is not exhaustive and is not meant to be chronological or assumes one has necessarily led to the next, as that is way too simple considering feedback mechanisms involved. The deeply neg forecast NAO is not included as that is reflective of the predicted atmospheric state, not a driver in its own right. Firstly, perhaps crucially, we are looking at a trop-lead (bottom up) warming occurring here. We are coming off a sustained +AAM period within an anomalously prolonged ENSO state of La Niña. The Pacific forcing dropping back into COD, shown on the MJO, and the timing of such, I actually think could play into our hands and not retrogress everything tooo quickly (may lessen the chance of a West based NAO). Then we have the likelihood of a further Pacific activity to reinvigorate a likely waning pattern later into the month? Whilst all this potentially prepares a substantial strat warming to hit after that? But, and it’s a big but, such major driver interactions and couplings with other such major drivers often produce leftfield results, sometimes on the edge or outside the normal spectrum, and by that very nature, not necessarily always good ones. Certainly expect enhanced model confusion. I’ve seen SSWs balls up a perfectly good tropospheric lead set up before! But there will be no moaning from me, give me this over a standard November into December any day of the week, I’ll happily take my chances with what is showing here please. I’d say the signs are as good as we’ve seen for 12 years at this stage of the winter, sorry, autumn! And we remember how that turned out last time.

Great chart output today. Later in November in through December is when the strat vortex undergoes it’s Rapid Intensification stage for the winter. This year is no different and it has indeed being winding up (un)nicely. The Tropospheric vortex is following, with loose coupling. So, around now, and the next couple of weeks, it should be an ideal time to hit it and hit it hard. More susceptible than a mature vortex and then keep prod prod prodding away to stop it from trying to kick back off again. Looking forward to a good ECM.