SMU

The trend of the GFS ensembles from day 10 - 16 is to drop the vortex into siberia -- which has been suggested for a few days now- many many runs depict a strong 2 wave pattern - with this being the cherry on the somewhat icy cake - I may go & check the October AO date record today - it could be under threat-- S

Evening All- So I thought I would just expand on Rogers review of hoping October would hold some relevance into the Winter Months- the overwhelming data since 1950 is that there is very little to suggest that there's any significant correlation, thats because for as many months you find Negative from an AO perspective correlating into Winter, you can find as many positive ones that tip the balance- This certainly fits to the zone (-1 < to >+1) AO However in more recent October years circa 2001 onward the height profiles over the pole ( relating to the rapid loss of ice & subsequent change in feed-backs) have become more extreme & amplified - From 2001-2016 there have been 2 months below -1.5 AO (2009 + 12) & one rounded to 1.5 ( 2002 ) - so 50 years with zero & then 16 with 3... whilst being a small sample size seems 'fairly' significant & outside the boundary of what you would label 'fluctuations' - Adding more meat to the bones & trying to link this into Winter is the following-- The X2 record breaking Octobers for Negative AO are 2009 ( -1.54) & 2012 ( -1.51 ) - Below are the AO values for DJF 2009 - Dec -3.4 ** ( record Breaking in 66 years ) Jan -2.58 ( 6th lowest in 66 years ) Feb -4,26 ( Record Breaking in 66 years ) 2012 - Dec -1.74 Jan -0.6 Feb -1.00 + March -3.185 ( record Breaking in 66 years ) So - Co-incidental ??? I doubt it, 3 record breaking negative AO months in Winters ( March INC ) following the record breaking Negative AO's in October..... 2002 - Dec -1.59 Jan -0.47 Feb +0.12 - Thats a pretty good hit rate for the 3 record months - 9/10 negative AOs & The December / Feb & March records Smashed. The NOAA say the AO correlation to the NAO is around 0.7 - & along these 10 months the NAO was negative for 6 months which supports that claim. - Whilst I am not spending a great deal of time on the flip side with a positive AO- its worth mentioning that within the years highlighted again ( 2001 onwards ) the December +NAO record was smashed in 2011- @ + 2.52 & challenged again in 2015 with + 2.24, The January +NAO record was beaten in 2005, only to be smashed in 2015 @ + 1.79 & 2016 Sits 4th all time positive @ 1.58 ( only surpassed by 89 & 97) The evidence is overwhelming that the polar height field is going from one extreme to the other - & the old fashioned Neutral type patterns ( NAO & AO -1.5 < > +1.5 ) are being forgotten about. This essentially renders any pattern matching USELESS Pre 2000. Maybe even pre 2007, we are now clearly in what I can only label the POST large teapot - & Ian Browns large teapot >1988 is RIP. So where does that leave Oct 16 - Well the sample size is Small - only 2 months @ sub -1.5, but both Winters combined delivered record breaking polar Statistics. Lets look where we are month to date & with high confidence to the midpoint of the month the 16th. - To set a new record @ -1.6 we need the total monthly negativity to be -50. (-1.6 over 31 days ) Heres the data so far, http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml I put us around -35 to the 16th (-2.18) leaving 15 days to average -1. The ensemble Mean is clearly guiding us to a secondary trough starting around the 20th, so *IF* this verifies even to a lower degree the models suggest another -1 to -2 second half of the month. October 16 is looking to SMASH the record as it stands- & in my book based on the evidence provided that suggests a STRONG probability that 1 month of our winter will be close to record -AO & the at least 1 other month will be sub -1. The 0.7 Correlation slightly dilutes the impacts, however based on this small snapshot I would be forecasting a 2/3 -NAO winter with a 3/4 probability if you include March - which whilst not a Winter month can deliver spectacular winter weather. Whilst we are only at the midpoint of October, Im looking for some ( but NOT ALL ) underpinning of -AO pattern in November, this is also where the statistical evidence gathered over 60 years supports a VERY good correlation that a November AO of SUB -1 supports an 84% chance that each winter month will be Negative - Here is the Evidence. November Months with sub -1 recorded. ( we haven't had one for 14 years )- 1952,55,57,59,62,65,68,80,85,98,00 & 02 = 12 Years. Of these 36 Months 30 Winter Months were Negative AO -- 84% & the NAO was 19/36 -- 52%. Adding to this across 36 Months there was only 2 +1 NAO months - Dec 65, Jan 86 ... I believe that Statistically that represents good value that November -AO sets the tone for Winter .... But only again within the bounds where -1 was the monthly result ( the neutral zone doesn't give an even picture ) Reversing the polarity again, for +1 AO Novembers we get 1978,93,94,11,13,15 = 18 Months.. The following winter AO only manages 6 Positive Months, so only 33% -However these winters NAO was positive 15/18 Months ( & of those its every year post 78 was positive ) - 84% correlated !! Look at that huge icelandic low pressure - To Summarise then: October 16 is currently on course to be a record breaker & from the 2 like for like years we should have moderate expectations that the following Winter should produce a significantly -AO pattern & a similarly but diluted down -NAO pattern. its only moderate confidence because of the small sample size. If the AO comes in negative for November- Ideally sub -1 then our confidence in the above forecast should move from moderate to HIGH expectations- & at that point I would give a high probability of a below average winter with higher incidence of snowfall. All eyes on the AO for the remainder of OCT & NOV to hopefully set the tone for the Winter... S

Updated AO ensembles- another trough developing after the rise- however nothing nailed on that yet- if we want a record breaking October - Sub -1.6 month then the total for the 31 days needs to be 49.( negative ) At a quick stab out to the 16th we will be about 34-36 - so on the way there... another update in 4-5 days S

Afternoon, looking at the bigger picture I dont see any particular warm up other than a glancing blow from the SE - Post that, more atlantic blocking signals some moderated cooler PM air moving SE- & out into the day 10 onwards plots - there is only one clear picture & that is the amount of polar blocking still developing & fracturing the vortex- I have some interesting stats to show for November Months & HLBs/AO state - however I will save that for a few weeks down the line ! S

Well well - an interesting 48 period of model watching - 24 hours ago the models moved away from the retrograde scenario & replaced it with hope of a warm southerly - Now just 24 hours later thats been shunted away east as the Upper trough repositions to the south / south west of the UK - delivering cool ENE winds.. interesting...

I think I hinted @ this with the October AO ( thus far ) supporting the follow on through the Winter...

Well well - a backtrack of sorts from the models today - lots of blocking to the NE still - however the ECM allows this to move into a position that creates a sharp southerly flow- late warmth still an option on the table - which most would enjoy !

^^ look at the 2 most negative Octs - 2009 & 2012 - then look at the following winterS AO the following 2 most negative OCTs ( at a glance ) 2002 is third- from the above 3 winters out of 9 months these were the AOs ranked -4.2 -3.6 -2.5 -1.7 -1.6 -1.0 -0.6 -0.4 +0.1 thats 8/9 plus mar 2013 was - 3.18 october 1979 was the only other close year. 2016 on track to smash the -AO record.

Updated AO ensembles yes thats a run sub -6 in there S This is significant !!

Todays drizzle would have been snow flakes & grains in winter.... - look what you would have won !!! models projecting chilly / cold weather persisting out to midmonth with a true greenland High pressure--

You could be right Nov 09 & Nov 12 saw a pattern relaxation in November ( although both months AO came in slightly negative ) S

I would hazard a guess that based on octobers signal there will be more suggestion of blocking into November- The signals of a return to mobility are on the outskirts of model accuracy & more in tune with the way the models blend in climatology as opposed to anything significant.. All eyes on the AO as thats the most significant feature of autumn so far... Record breaking negative..

So.... based on the assumption that the AO comes in sub -1.5 for the month the winter best fit analogue would be 2012/13- The wildcard being the QBO - as it was recorded westerly again in September - although it didnt change that much from August > Sept toward any more positive- Also the solar flux this winter will be lower- as it stands ( as a prediction based on the oct monthly AO ) theres an above average chance of at least one Winter month with an AO below -2.5, correlating around 0.7 to the NAO state... if I was a betting man there appears to be an above average chance of at least 1 below average month - A bit like last year - December a very high probability that it was going to be +VE its not about definates - its about probabilities- S

Day 10 GFS snowline well advanced for October s

Spectacular ECM tonight - Perfect easterly peaking at 168 with a scandi retrograde out to 240.... if only it was Winter ! - Vortex? what Vortex? s

Afternoon should the 12z GFS varify then it all but locks in a well below average month - with a flow from a Northerly / Easterly quadrent for the next 10-12 days at least... it would have to be a big swing to warm southeries to salvage a return to normal values ( it could happen !) s

So just going back to my musings regarding the AO- I may spend some more time reviewing it this week - however as I mentioned the other day an October Month has only ever come out below -1.5 twice & that was 2012 & 2009- if we look at the 12z & certainly the ensemble mean from the 00z run which takes us towards midmonth then that record potentially seems under threat - I would hazard a guess we are around -2 by mid month if it varifies - of course with 2 weeks post that then it could all change... what does it mean, well there have been some assertions that due to the ice loss & subsequent reduction in thermal gradient that October would see a slower start to the zonal westerlies & that more negative AOs would become apparent- & this certainly holds water with the record -1.5 Oct 2012 as it was also the lowest ice minimum year - However if this was the case the since 2007 this should have been apparent, but the results are a mixed bag- The 2 record years 09 & 12 mixed in with generally averageness - so maybe whilst the ice loss theory probably plays a part- I suspect thats its just aome of the make up- That said it seems that it seems to support a big negative swing towards 'negativeness' V what may have been the case in that year - So my brief summary would be that the October AO isnt 100% correlated to a blocked winter, however if it turns out heavily negative then one would assume the background support is there as well- I would also add, that -AO octobers followed by -AO novembers tend to really support a blocked winter as well- however I need to check that ! S PS 2009 oct -1.5 dec -3.4 jan -2.4 feb -4.2 2012 oct -1.5 dec -1.7 march -3.18

Hi Mapanz It is rare - I went through every October since 1954 on the NOAA website & theres probably less that 5 occasions where the -AO went below -3.. sadly their daily data stops in 2013 so I dont know about 2014 it does however have the whole month on there & it netted out @ -1.1 which isnt very significant- A bit like the current position, its only perhaps significant if its sustainable... s

Its worth noting that the current AO metric is tanking towards -4 which for October is very rare- Also from a record perspective the most negative October monthly AO is I think 2012 - where the following 5 months were also negative, with March 2013 also record breaking could there be a loose connection - Oct 12 record @- 1.5 Mar 13 record @ -3.18 keep an eye on it.....

The london 850s show a trend that has been missing from the Uk for some considerable time... s

Exciting 'NO' interesting 'YES' at day 6 Minus 6's over central / eastern europe

So the ECM has continues to develop the Easterly flow over the last 48 hours to be homing in on this set up at day 4 Now we have hit October the perfect winter synoptics will certainly deliver cool / colder upper air - The seasonal mean for England is about +6/7c & the ensembles point to a 'cool' pool at 0c / -1c so the upper air is around 7/8c below the normal - thats rare these days as October in more recent years has seen warm air in the UK Nice !

Yes interesting output today - almost dream winter synoptics on the ECM & more particular the UKMO with those long fetch easterlies- waiting the important september QBO data !!!

So the big totals of rain are just a smidge further WNW than progged into the NW of our region - but the fat lady isnt singing yet..

First kent cell firing up now - maidstone way gone purple ..... heading West ...