snowwman

Probably. We may even be there next month, but any warming pulses would delay that.

Indeed, the correlation here appears weak, but only if you're taking of extremes (la Nina and El Nino). Here, cool side of neutral touching on la Nina seems to be ideal, though you need to factor- in the QBO and solar activity (as measured by cosmic ray influx, not sunspots (as there's a delay in the former, which is what influences the jet- stream, relative to the latter, in odd- numbered cycles).

The blob seems to have moved East, and partly extends to the Mediterranean; this is likely to reflect atmospheric dynamics rather than ocean currents, but in any case, it might indicate a tendency for a more Southerly- tracking jet this year. The jet seems to have flowed- around the edges of this blob over the years, and this resulted In December 2015 being record- breakingly mild. If the anomaly stays where it is this year, however, we may be in for a very diiffent December, and winter generally.

Yes, ECMWF is going for the 25th at the moment. However, I've noted a slight tendency to underplay Easterlies at the equator at times, and if this also applies to 60N, then the vortex may be somewhat later.

CPC now puts Nina ahead of Nino for winter: http://www.google.co.uk/url?q=http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf&sa=U&ved=0ahUKEwi8_sXdguTVAhUEEVAKHZHqD4kQFggLMAA&usg=AFQjCNG4IpbNEDz_fJDqlOvjJ77HOWtBLQ , with neutral the preferred option. However, the way the models have been trending, I say that the most likely outcome is La Nina.

After a string of summers feturing heatwaves or repetitive Spanish plumes, every summer since 2014, I'm happy with the way this Summer has turned out, on the whole although GFS's insistence, now in the ensemble mean, on a height- rise over our shores, is rather worrying. I'm hoping that ECMWF is has it nailed and that this Summer ends mercifully.

Latest SST are out- http://www.cpc.ncep.noaa.gov/data/indices/wksst8110.for and show a cooling in all enso regions.

Amazingly fast cooling in the far Pacific: http://weather.unisys.com/surface/sfc_daily.php?plot=ssa&inv=0&t=cur . At this rate, we'll get a La Nina very soon.

Indeed, I think it's difficult to imagine El Nino continuing to be preferred over La Nina. The move toward Neural as the most likely outcome by winter's start will eventually result in La Nina being the most likely outcome, I think, and as has been mentioned, CFv2 has been keen on this possibility of late.

Second most negative first two months at the 30mb level on record, if my calculation using the FUB data is correct.

There's no clear link unless you factor in solar activity. I recall a study by Labitzke et al which concluded that the vortex is weak in Easterly QBO winters at solar minimum and in Westerly QBO winters at solar maximum. Where I probably agree is the link between split stratospheric vortexes and cold winters- I can find no link in the research I've done which confirms the oft- quoted causative effect; indeed, a split strat. vortex might even be harmful, though certainly a disturbed vortex may be crucial. This link: http://journals.ametsoc.org/doi/full/10.1175/JAS3883.1 might provide some useful links, though I haven't had time to read it.

Much interesting information here. I haven't done the number crunching myself, and I wonder whether there's any increase incidence in phases 7 and 8 during cool end of neutral and a strong upper (or lower-) strat EasterlyQBO.

At the moment, yes, but then the forecasts seem to be moving slowly in the cool direction. CFSv2 even recently forecast a very weak La nina for NDJ, and still, the forecast is for cool side of neutral by then: http://www.cpc.ncep.noaa.gov/products/CFSv2/CFSv2seasonal.shtml . Also, there has been a sudden cooling in this region and region 4 (from what I can make out) in the past week. My guess is that the strong Easterly QBO is what's primarily feeding this.

Yup, 2014 and '15 we had protracted heatwaves here in South Wales, and last year we had so many Spanish Plumes I lost count. I'm grateful for a Summer of more sensible weather, on the whole.

I've reached the conclusion that severe winters have more to do with absolute solar activity and the length of time that activity has been anomalously low than they do with relative levels- for example the location in the cycle. Depending on what station you're examining, cosmic ray levels are already at 2009 levels. http://www.nmdb.eu/nest/ . Cool side of neutral enso conditions, an Easterly QBO and such levels of solar activity are, from what I can gather, extremely well positioned for an exceptional winter.

The reason for the "hold- up" in the progression of the Easterly QBO is that the lower levels of the stratosphere were anomalously westerly in the lower strat during the Westerly phase which is on the way out at the moment; actually, by historical standards, there is no hold up- the Easterly QBO is progressing down the stratosphere no less quickly than average, now that it's encountered the anomalously Westerly lower- reaches of the strat; it's just a matter of time before those levels turn Easterly, too. A further point is that winters we consider "Easterly", e.g. 1962/'63, weren't Easterly at the 70mb level until way later than now, and when winter was over!

The 30mb level isn't negative in the chart yet- only the 10, 15 and 20, but June's value will be negative at 30mb.

I recall reading that an Easterly QBO renders the vortex weak only during low solar activity; Karin Labitzke did some research on this. I've noted that when geomagnetic indices have been anomalously weak for a few years or when there's a sudden plunge in said indides (e.g. Ap index), cold winters tend to occur. At the moment, it seems to me that cosmic ray monitors suggest that we're at the sort of level we experienced in 2009 and 2010.

I'd take this over a heatwave hands down.

I can't abide warm weather, and I was beginning to get that sinking feeling again when ECMwF was suggesting another spell of it. Thankfully, the ensembles weren't backing it, and the expected swing back to unsettled happened this morning.

What surprises me more than anything is that there's no mention which I can find on the web of the strength of this Easterly QBO. The preliminary data for the first two months of the phase at the 10mb level, the first two months at the 15mb level, and the first month at the 10mb level, suggest, taken as an average, that this is very much the strongest Easterly on record. Also, the fall in wind speed between the penultimate and final month of the Westerly at the 30mb level is the second largest on record, and this Easterly may be the first to propagate from the 30mb to the 50mb level in less than 2 months.

Nice bit of research. I came to the same conclusion re. Westerly QBOs. They don't spell mild. They seem more likely than Easterly QBOs to be correlated with extreme mild or extreme cold.

Perhaps the latest GFS run at D16 has found a solution the the difficulty of the Northerly considering the strong vortex over Canada, now gone in this chart: .

Exactly, KT, and the low heights seeping deep into the Mediterranean, even by ECM: , will make it difficult for that high to sink.

The highly unusual patterns this Autumn/ winter is likely a big factor- it may be more difficult than usual for the models to accurately plot changes. Also means we shouldn't take as correct any model output which suggests mild just because that's what's often happened before.