Alex

Not much has been said about the other variables so lets take a step back and have a look at some other drivers of our atmosphere, 1) MJO - http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml We are moving fast into phase 6, this suggests blocking to our west/northwest with a trough to the east. http://raleighwx.americanwx.com/MJO/JanuaryPhase6500mb.gif 2) angular momentum is rising - at this stage this would support blocking http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/gltotaam.sig.90day.gif Alot has been said about the stratospheric warming recently, but the current highly variable models isn't helped by the fast moving MJO and rapidly rising angular momentum. My conclusion is that we are likely to see quite possibly the most prolonged cold spell this winter, however the stability of these variable will help determine the strength of the blocking in place. Keep an eye out!

4.9c for me please

Well not very seasonal here 8.1c, thunderstorms with hail in Chelmsford Essex at 08:30! Loving it though.

The upcoming mild spell was always likely, the recent sharp warming in the stratosphere has even replaced by a rapid cooling. http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/pole30_n.html This is supported by a ever reducing angular momentum (hardly conclusive to blocking). http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/gltotaam.sig.90day.gif The only straw to clutch is the MJO heading Into phase 1, this can support a blocking signal. http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml These teleconnections do support a revitalised PV, its where it sets up that will be the important factor!

4.7c for me please

This cold spell was always going to struggle to last under a cold stratosphere, the high GLAAM levels can promote blocking but we also have a weak MJO. If the MJO can push into phase 8 this may be able to support some blocking later in the month. http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml It won't be helped though if the stratosphere continues cold, this normally spells zonal mild weather!

I think this is why the models are struggling a bit, coupled with a weak MJO it's hardly compelling evidence for either a blocked or zonal pattern, however I think it will be hard to get sustained cold under a cold stratosphere.

Thanks Ian, another decent analysis from the top of the tree. One thing I would like to know though is how much thought goes into teleconnections? I visited the Met Office on an open day this year and when I asked forecasters about teleconnections they seemed rather unknowledgeable? I'm guessing most of the work is really upto 5 days ahead, but would be interested in finding out what's happening at the top of the tree and whether the 6-15, 16-30 and seasonal forecasts are more based on ECM 32 dayer and other ECM outputs / CFS rather than really looking deep into MJO / angular momentum / stratospheric conditions etc.

I would hate to bang my own trumpet but I did warn people about the chances of this spell being short, the backtracking on the models of the longevity of this upcoming cold spell is hardly surprising with the stratosphere so cold, the PV will have little problems in re establishing under this ideal situation. http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/pole30_n.html The MJO is stil sat in its central core with little influence. http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml The blip in the northern hemispheric weather pattern can be put down to a sharp rise in angular momentum. http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/gltotaam.sig.90day.gif However my thoughts are still that it could become colder again towards the end of December, alot will depend on the stratosphere however with the MJO likely to move into phase 8 eventually, this is a sign of blocking.

Everyone seems to be too fascinated by the GFS outputs in FI, don't forget that although they sometimes pick out a correct trend, they often don't and will change quickly thoughout each run. Onto the models and I think cold lovers will need to be aware of the cold stratosphere, I think we will see a cold spell coming up but how long it will last is a big question. A cold stratosphere will allow the PV to rebuild and the PV may not be disturbed too much in the near future. http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/pole30_n.html Also worth looking out for trends in the Ensembles, the current 00z picks out a modest average trend, with the operational possibly labelled as a cold outlier. http://www.wetterzentrale.de/pics/MT8_London_ens.png

Hi GP, The stratosphere is still much colder than normal surely this will restrict any blocking to just a few days? http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/pole30_n.html MJO also progged to be weak by the GFS? http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml

Why would low heights in the med be a hindrance? If anything it helps as ridges set up elsewhere, if they set up to our south - then that generally means Bartlett territory or the jet slap bang running west to east through the UK bringing mild wet weather.

Looking at the models and particularly the ensembles, the Synoptics are definately heading in the right direction if cold conditions floats your boat. Initially I suspect a scandi/euro high will bring in reasonably mild south-south easterlies but that high looks like receeding a touch north with time and with that brings the threat of colder uppers mixing into the equation and easterlies to bring the cold uppers in. http://www.wetterzentrale.de/pics/MT8_London_ens.png

Interesting that some members on the most recent runs of GFS op are showing some colder outlooks but this is rather insignificant as the bulk remain in the average sector. I wouldn't be surprised if the country settled down in Dec with much colder conditions however anyone expecting a dec 2010 again may have to wait longer than 2 years, even in the milder winters - often a spell of anticyclonic cold and at times foggy weather was prevalent this was often in December around the period before Xmas. Although GP alludes to some signs of the background supporting northern blocking this doesn't necessarily mean cold weather, we could get a west based -nao like we had recently or even a scandi high with a trough close to the west uk which can promote southerly winds as lows are steered away south to north rather than west to east. I think cold lovers need more patience this year but I dont foresee a 2010 or 2009 type winter month.

EML is right - * cooler than average stratosphere, unattactive for cold lovers as it can lower heights to the north (PV). http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/pole30_n.html * rising angular momentum - although low it is rising and for pressure to rise to our north - angular momentum should be low, rising am may encourage lower heights again. http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/gltotaam.sig.90day.gif * mjo heading into it's central core - so technically could rule this out if the GFS is correct. http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml The link below shows exactly where I think we are heading for the medium term ie 10-15 days, lower heights to the north , high pressure to the south but not quite a Bartlett scenairo, similar to current spell of cold zonal with maybe some milder interludes. December may become different but not yet on this evidence! http://www.wetterzentrale.de/pics/Rtavn1441.html

Thanks GP, I am still interested in whether hurricane Sandy will alter any of the Atlantic patterns.

Interesting GP however I don't remember apart from 2010, that many of the more recent analogues ie 2005/2006 winters produced much in the way of cold/snow - Dec 06 was rather like 2011 if I recall it right. 2005 I think cold lovers had to wait until the deep realms of Feb for any decent snow and even then it was questionable compared to some recent years. My question is what was different about them years as it looks like northern blocking was prevelent.

Nice to see people optimistic this morning but I think some are over egging it, the GFS ensembles for the 00z tell the story, below average temps now becoming average with time, continuing unsettled. The ECM 00z looks similar to the GFS with the PV setting up shop to our north and a ridge setting up to the west of us but not too far away to influence things maybe cold and dry - mid November? http://www.wetterzentrale.de/pics/MT8_London_ens.png

7.1c - rather average like recent years with milder 2nd half.

As you live in Great Baddow - where I indeed live, you may recall an incident in June where warm air from the south dragged sand/dust from the sahara and deposited it across everyone's cars!

As John said i'm not sure why ppl are so dissapointed, an 8-10c drop in temperature is noticeable. Snowfall is rare for a reason in October and the seas are still relatively warm. If it was December or January then yes the -5c uppers that will be evident as per the ECM run this morning and would probably bring a very cold stint of weather. My take on the weather beyond October doesn't bode well for cold lovers, the stratosphere is looking likely to stay average/below average and this will help aid a Stronger PV during November.

I wonder what the verification stats are for the Met model because maybe it's me but I think it's done a poor job this year with trends etc, one major error was the August southeast heatwave! Moving onto the models and I think the ECM has got into a bit of a mess on the 00z it strengthens heights over Greenland then the high starts slipping southeast again?

I've been reading everyone's input and alot of it in my eyes is people getting ahead of themselves. 1) I understand about cold pooling and the affects of a PV not establishing, however I have 2010/11 winter as a great example where as soon as Christmas was over, the jet moved north and the cold was pushed back east. What is to say that despite a weak PV that we will have a westerly based -NAO or even a northern block in the wrong place dragging in southerlies? 2) it's October!!! Although November is around the corner we still have 15 days to go and winter starts on the 1st December so that's 45days where a PV could establish. 3) April 2011 rings a bell! Lovely summer Synoptics destroyed to similar Synoptics to today where northern blocking took hold, even if October comes in below avg, this has only a little bearing on December Synoptics. I don't want to burst anyone's bubble but it is too early to look at winter as some 1962/63 repeat and looking back at the record books, cold Octobers seem to have no bearing on the upcoming winter. Another reason for this post is my own opinion as it stands which is for a very average, wet winter, sorry cold lovers but I can some real cold but often too far east! I will explain more in November.

I would say 27c at day and 18c at night is ideal. No aircon, heating or anything required and could easily walk around with jeans and t shirt.

Although some daily records may fall I doubt 32.4c which is the highest temp so far this year will be beaten, we had a stronger sun and a 17/18c 850hpa line across the southeast, this time a 15c line with slightly less strong sun can and may push temps upto 30c.