Duane S.

Basically, December is make or break for the winter, we need some decent wave activity or the winter will be dominated by the vortex and as such preclude any HLB from being able to form. Nothing new there what with the background drivers as they are, this is a very real possibility. But luckily! plenty of time left yet for us to head down an altogether different winter's path. Personally am still convinced we are going to see a big uptick in single wave activity from mid month onwards.

00z carries on from where the 18z left off... GEFS Ens not really buying into it yet (no real surprise) but no doubt in my mind that there is a window of opportunity around mid month for our next cold spell to commence. Something stirring higher up in the Strat as well?

One day away from winter and model fatigue has already set in by the looks of it! Anyway, 18z is an excellent run and whilst yes it is the 18z, not to be dismissed. It takes us into the period when this sort of setup is more than viable IMO. Window of opportunity will be there as the main vortex activity shifts away from the Greenland locale and the jet heads south.

5.2 for me please.

More hints of some interest mid-month as the PV moves away, allowing height rises to our NW. I think we are going to see the models play about with this a lot in the coming days, leading to some interesting FI chart output! I find this trend interesting, not for once a toasty max but a very tepid min forecast.

As per BA's above, it could be a long old December if we don't get wave activity into the mix Westerly QBO helping the u wind drive down to the 30mb level with relative ease, never a pretty sight. However, I suspect though that the first decent single wave attack is not too far away now, all eyes on Mid December onwards I would say.

Interesting (and not in a good way), the difference between the likes of 09 and now at mid Strat level, a veritable world of difference in vortex strength. I do struggle to see any meaningful HLB manifesting for the next 3 weeks plus looking at the NH hemisphere state etc. However I say let the vortex continue to wind itself up into a frenzy (and it will), the bigger and the more spectacular the fall. Still plumping for strong Wave 1 displacement followed by continued wave 2 activity to spell the start of the end of its dominance late in December, with some fun along the way.

I think a very +NAO is fairly likely now going through at least the first week of December, probably 2. Something inbetween a more easterly progression of the vortex scenario with very wet windy conditions for us and the SH edging west (but just out of reach), keeping us in a no mans land scenario. Thereafter up for grabs I would say. I could see the next phase being energy diving SE with very disturbed weather for us and some welcome snow over the Alps in time for Xmas (topping up on the great dumping they are about to receive). Then I think comes our window of opportunity. I think by then we will be watching a significant wave1 event and waiting to see what it will mean for us heading towards the end of the month. As somebody posted earlier, I think we are going to have to endure the pain to get the gain.

ECM snatches victory from the jaws of defeat thanks to that Eastern Canadian trough giving us a quick follow on cold snap. Difficult to be sure where we would go from that position if it were to verify. My money would be on PM airmass for a bit followed by a window of opportunity for further height rises to our NW thereafter. All pie in the sky though as much to be resolved before we get there.

Split up to 30mb and evidence of the squeeze is seen a lot higher as well. One to watch in the coming days I reckon.

What are peoples' thoughts on this Asian warming? It is fairly weak and doesn't appear to be getting any stronger but it seems to be enough to disrupt the vortex at the top. Are we looking at a subtle pincer attack on the strat vortex taking place, from the top down and up from the troposphere? With a lack of any strong wave activity, I wonder if a low level but importantly, sustained, warming would be sufficient to work its way down through the ever growing vortex or will it likely just hit a brick wall? I'm going for the latter as I suppose a bit of vortex disruption at the top is one thing, infiltrating this beast mid level with a W-QBO fuelling it, is likely to be altogether another thing.

Yep, my feeling too that it is (currently) difficult to see any sort of proper sustained cold spell emanating out of this for this reasons you state above. But with such a powerful strat vortex I would gladly take what the ECM is offering as an early winter bonus, even if it was short lived.

Indeed, which was of course followed by...

Blimey, not half bad chart output tonight! From the ECM especially. We've been almost entire winters before without seeing such good runs. Trouble is of course we've been here before and I suspect that is the main reason this forum isn't going into total meltdown right now (because the ECM run and its further potential warrants it) is that we've all been burnt with teasing ECM over-amplification charts many times before. BUT there is a different non-standard 'look' about the NH profile this lead up to winter, I too spot a 1978 esque look with that tasty D10 chart from the ECM. Upstream, the jet direction/angle over the states would seem to be favourable for an eventual window of opportunity to pump warm air off the eastern seaboard into towards Greenland, so I think it has every chance of occurring. To what degree and just how many hurdles to be cleared, yet to be determined! Interesting to see the Strat taking a back seat with this tropospheric led cold spell on the cards (potentially at least). It has seemingly popped up with very little warning. I posted a chart a couple of days back from one of the GEFS Ens that showed this evolution but it was way further into FI and I must admit that I didn't see anything happening as quickly as the the ECM would have us believing but maybe this time ECM... ?

Some interesting variations on far FI on the 12z run including this peach... Unlikely of course as there is little support for what causes it, aka trough disruption central Canda which throws up strong ridging ahead from the Eastern Seaboard into the Arctic, however there is undoubtably a continued trend to set up the growing vortex away from Greenland. That in itself increases our chances of a cold spell 3 fold than if the vortex sets up residence over Greenland (may well still occur of course). Plenty of fun weather watching ahead as we near winter proper I feel!

Ref an SSW, I thought solar cycle max / inclining phase of the cycle is also needed for this correlation. We're in the declining phase but perhaps in uncharted waters as in having the exact combo of a strong established El Niño, established W-QBO and declining solar output? I do think the Strat and consequentially trop vortex is simply going to be too strong for any wave activity to seriously hinder its growth until into 2016 but as others have mentioned, it doesn't automatically mean it will sit slap bang over Greenland for the next 2 months. A vortex centred on the other side of the pole is probably our best realistic chance for some proper cold spells this side of Xmas, so here's hoping for a late December '81 repeat. Edit: Actually meant December '78! (although 81 not too shabby either)

Steep drop off on the latest forecast, although the Arctic pressure anomaly will be dropping off from a very high peak (if indeed it does reaches that). When was the last time +5 was hit I wonder?

Far FI of the 00z GFS would be banked by the vast majority here I suspect. Huge Mid-Atlantic block, no doubting a set up like that would lead to the first (and an early) cold spell of the winter for most, more of the same please...

It's been difficult to drag myself out of summer hibernation this year, the 4 wave resulting in a Euro High pattern is the stuff of nightmares as most of us here I'm sure know how difficult it can be to shift. But hey, it's November, not January, so no worries on the time front at least! The first half of November therefore looks highly unlikely to produce our first proper cold spell of the season, I think the Atlantic breaking through and a spell of wet and stormy weather would be the favoured option ahead of any cold spell anyway. Which, let's face it, probably holds true for a good 9 out of 10 Novembers! That said, there have been a few subtle hints out in far FI of the past few GFS runs that a more favourable (in terms of cold) pattern change may be on the cards for Mid month. Ensembles will come into their own here, as will the anomaly charts, on picking up a potential change.

Ah.. The first proper sign of winter approaching, not the geese flying overhead, leaves falling from trees but Chiono opening the Strat thread! The second sign naturally is the Berlin strat charts fully opening for business on the 1st of November :-) Fantastic summary, as always, Chiono, probably cementing most people's thoughts, which is much less (on occasion, wild!) optimism aka 14/15's E-QBO / high snow cover pre-winter frenzy and a more tempered W-QBO / declining solar cycle / dice generally less loaded on paper viewpoint. But as always a strong EL Nino will be the wild card here, plenty up for grabs. Sustained Wave1 activity looks a likely outcome and as we know displacement can be good for us but more often than not a thorn in our side as cold plunges down through Eastern Europe or away to our west down through the Mid Atlantic, possibly the form horse this time around. But better have wave activity than not, especially early winter as the vortex will be winding itself up and being fuelled from the W-QBO as well no doubt. Less proper sustained blocking but with a bit of luck thrown in, I can see a couple of real cold snowy spells coming about in the way 1981 produced. Now that sounds like wild optimism! :-)

Got that wrong then....

Flashing every 5 seconds and just offshore, getting close

We've had the child, I think daddy is coming. Constant flashing just to the south

A few distant flashes to the south and some big big drops just starting

First rumble. Very stuffy outside