Nouska

Wish I had missed the boat! A Titanic episode for a lot of us and not a bloody iceberg in sight.

I know this should be in the stratosphere thread but it's not very busy at the moment so hope it's OK. This particular SSW seems to have had a strong response right through the layers in double quick time. Z500 last ten days of 2012 Z500 first ten days of 2013 The 30mb gif that covers the period. Images courtesy of JMA and other atmospheric levels to show the rapid propagation here. http://ds.data.jma.go.jp/gmd/tcc/tcc/products/clisys/figures/db_hist_pen_tcc.html

For those with no access to the extended EPS mean, a wee gif of the eleven to fifteen day progression. 850 temps are a bit lower than the 00Z run.

I have to take issue with this: at no time was it specified precisely where the blocking would be. The end of November/first days of December are very blocked and very cold at the surface. The problem lies in how people interpreted this information and the inability to see the hoar frost covered landscape as a scene of winter cold. No snow = no cold = winter over! Impossible to forecast for that degree of pessimism.

I don't know about that but it is all here - for two years - if anyone wants to have a look. http://www.ecmwf.int/en/forecasts/charts/mofc_multi/mofc_multi_verification_anomaly_family_vanomaly?time=2016111400,0,2016111400&parameter=2m temperature&area=Europe Z500 ... http://www.ecmwf.int/en/forecasts/charts/mofc_multi/mofc_multi_verification_anomaly_family_flowz500?time=2016111400,0,2016111400

Kara sea blocking high is a response to good early snow cover and low ice in the region - yep - fine example of this in action for the first ten days of January 2016! Was this not the very thorn in the side of expected improvements in the outlook last year? As an aside, a good example of how seeing this chart as an anomaly forecast might not tell the full story.

One thing did strike me regarding the extended EPS - a more distinct clustering around cold conditions at day fifteen. You would, under normal circumstances, expect the spread to widen by that range. I've used the SE sector of the Netherlands options.

Yes, it's not very often you see such charts before a SSW has done a job on the vortex. I suppose 2010 was a recent example but very different higher up in the stratosphere. 2010 = split from wave breaking - (I presume?) I think it was Ed who said the jet will not cross a split - it didn't. Now = Canadian warming You can see why modelling is showing a dipole anomaly, cross polar, split but it is not angled correctly to benefit us ... (yet) and there is no split to stop the Atlantic jet.

A very sensible approach in view of the difficulties this winter. I've recently read three professionally written (meteorological agency) forecasts for my more immediate location - all highlighting uncertainties and model divergence in outcome for the season. Discussing risk for periods of cold/very cold but also probabilities favouring milder climatological bias. Emphasis on ongoing updates as situation evolves.

3.6C for me, please.

You and me, both. About to make an inaugral entry on here. Remembering my first ever TWO comp entry in Dec.2010 and everybody snorting in derision at my sub zero figure. on them! Not getting the ADA vibes, visible back then, from the current model output but there's something afoot up there.

Just a ripple on a mill pond. Quietest rotation of the autumn. Just one variable in a host of known unknowns. Indeed! Somebody was asking when was the last time we had such an extended period of high pressure at this time of year - not very often, is the answer. This JMA link is useful for looking at anomalies in small chunks. Data back to 1958. http://ds.data.jma.go.jp/gmd/tcc/tcc/products/clisys/figures/db_hist_pen_tcc.html

Just reading the MedCOF seasonal forecast statement - recommending regular updates due to uncertainty. You are not alone in doing so. Sub-seasonal variations, not predictable a long time in advance, may dominate at times, so regular updates to the forecast are strongly recommended. In addition, local factors (for example SSTs in the smaller basins of the region) may shape local variability at a regional level. http://medcof.aemet.es/images/doc_events/medcof7/docMedcof7/Consensus_Statement_MedCOF-7.pdf

ENSO was weak Nino transitioning to moderate Nina. Solar cycle interesting as very dramatic drop in activity just prior to onset winter 39-40. Geomag fell off a cliff! http://isgi.unistra.fr/data_plot.php Stratosphere the polar opposite of this year. You'll get strat data a long way back on this ESRL link. http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/plot20thc.day.v2.pl Great work on the forecast guys - and good luck! Rather you than me trying to make sense of a very unusual picture.

Absolutely! I cannot see what the Met office see but I can see that the forecast strat profile at 30mb is an unusual occurence compared to recent times. A Canadian warming has been a prelude to some good early cold periods including the 'Daddy' of them all. Patience required and a realisation that things have changed a lot with regard to overall atmospheric conditions in the intervening decades.

I would say it is even earlier when you focus on the area of disagreement.

Looks like they saw a similar cold anomaly in January - holy grail synoptics. T 850 Z500 Strong wave 2, pre SSW split, in evidence there. An edit to keep to current topic. JMA progressing the pattern shown last week - gives a bit more confidence and continuity.

Some of the NWP has been suggesting tropical/subtropical genesis in the central Atlantic around the time frame - I suspect the rapid formation is just an example of the runs that develop. Edit ... good grief - put the specs on before jumping to type. I've no idea is the answer to the low south of Greenland. Thought it was the cut-off low in the central Atlantic. Higher up in the atmosphere good continuity for cross polar influences to be in evidence around day eight.

Absolutely! The monthly products have suggested a form of this pattern. Examination of historical situations where the upper atmosphere is configured as now, allows for this pattern to develop. Every situation is unique in how the lower atmosphere responds with surface features but IMO, absolutely no reason that some form of what we see in this run could not happen. The very fact complicated algorithms are producing the output is testament to that.

I don't think this paper has been posted in here. They look in a bit more detail at each summer month with regard to atmospheric patterns and corresponding ice melt. Observed anomalous atmospheric patterns in summers of unusual Arctic sea ice melt. https://core.ac.uk/download/pdf/30911652.pdf Not a very promising prospect for UK summers if they have got this right.

A final water vapour image of Angus. Would this be a good example of the 'scorpion tail' signature of a sting jet?

Maybe they are responding to some of the global modelling which wants to repeat the November pattern in February. I wonder what brings this pattern back - are they seeing a stratosphere happening to initiate this? I know the JMA have good strat coverage but not sure about BCC or NCAR products. WSI are impressed by CESM performance in summer and autumn so maybe weighting on that.

It's the story being told in all the monthly products so no surprise to see it coming into view on the deterministic runs. Now, the trick will be, to bring it into short range. We've spent three years hanging on every move of the strat to pull something out of the bag - too many worries about what is going on up there! I get the impression, some cannot see the wood for the trees.

The high res models went down to 962mb or thereabouts. AROME from 12Z Current

The sting jet is in the wrap-around of the core of the low. The AROME zoom has hourly time steps and it shows the strong winds just ahead of the centre. Best seen in the zoom option. Probably squall lines there too. http://www.meteociel.fr/modeles/aromezoom.php