Winter Forecast Now Online

[I remember Atlantic 252]

fantastic effort with forecast Stewart, although bit technical for me, but hope it comes off, certainly know your stuff

[BLAST FROM THE PAST]

An excellent piece of work there by Stewart. Three interesting comments for me in posts....JH mentioning 65/66 analogy. The one that meets more comparisons that any other....and if you look at the synoptic setup I would have to plump for that as a good match. This moves onto MBs comments...it is indeed very interesting that GPs LRF more than generally agrees/follows LRF by RJS and I. The third is the temp anomaly differential suggested by GP for Jan....there is a signal for a potential extreme cold outbreak in Jan....

BFTP

[ThunderStorms]

I liked this prediction !!

Very well explained, so much that i understood ... Lol

For me in Portugal i think this is very good news !!

Bad weather with very wind, rain and thunderstorms ....

I like, thank you Stewart !!

[damianslaw]

An interesting and informative read. The forecast highlights the many variables this winter and how due to the sheer number of how many are signalling colder weather when combined will appear to overide El Nino, not completely it seems but enough to produce some significant cold spells but probably not of any great length.

The forecast reflects my own views of the winter in that overall it will come out as very average temp wise, but this will mask the fact that there will be alternating cold and mild spells.

I said I would give my forecast for the winter this week and here goes -

Dec - main summary - generally unsettled, average temps in the north, slightly above in the south

A chily beginning for the north with wintry showers and nightime frosts, average temps in the south and fairly unsettled with rain about. The mid month period I expect to be mild with plenty of rain, however, cooler air will penetrate into Scotland from time to time with some hill snow. Southern parts could see some notably mild days. The latter part of the month likely ro remain unsettled but with average temps in the north so some further snowfall for the hills and I expect at least one major low level snow event in the north before the month is out, the south will stay wet with limited frost.

Jan- main summary - Fairly cold in the main with a notable cold dry spell at some point probably mid-late Jan, less rain

A wintry start in the north with heavy wet snowfalls, the south will be milder with rain but perhaps some snow on higher ground all courtesy of a southerly tracking jet, this giving way to milder conditions for a time for all with rain more likely everywhere. However, high pressure will come on the scene probably mid month ushering a generally cold frosty dry spell. By end of the month more unsettled again average temps.

Feb - main summary - Unsettled start, cold middle possible mild end

A difficult call, probably unsettled to start with average temps for many but a notable cold dry spell mid month, perhaps less settled towards the end.

Overall I think it will be a much snowier winter in the north than last year but less snowier in the south. Mostly unsettled in the main but with alternating cold unsettled spells and mild unsettled spells, unlike recent winters where the unsettled weather (last year excepted) has been synonimous with mild weather, however, a couple of cold dry spells. A bit of everything and certainly not the mild wet write off that I'm anticipating the Met Office to call.

I

[Schnee]

A very interesting read and I understood it

Looking forward to a seasonal January. Maybe, just maybe I could beat my 18ish inches in the January 1995 Yorkshire Snowstorm. Still not beaten yet!!!!!

[cooling climate]

Great work GP. Thanks for the time and effort that must have been put in for another top class

presentation.

It will be very interesting as we go through the season to see how close it varifies (I'm going

colder myself), but regardless of this, great work.

[BrickFielder]

Good forecast Stewart which I would agree with. I do have a couple of questions though.

1) The easterly QBO faltered somewhat last month ,do you expect this to pick up again as we go through the winter?

2) The current disturbed pattern has prevented ice build up towards svalbad, do you expect this to moderate any cold into northern Europe?

3) You linked the possibility of a weak stratospheric vortex to an increased brewer dobson circulation this year which research suggests is enhanced by CO2 levels, do you think a weaker stratospheric vortex is likely to continue in the coming years?

4) Disruptions to the stratospheric vortex have root causes like blocking high pressure systems in the troposphere, or from jet streams crossing mountain ranges, what format do you think these diruptions will take this winter? Will it be to split the vortex or to push the vortex away or towards the UK?

5) A pick up in the trade winds across the pacific will lift those warm sub surface temperatures, what are you using to determine when this will take place? For example is it when the MJO goes from phase 8 back to phase 1?

[chionomaniac]

Great forecast GP and good luck.

Interesting questions posed by BF there.

I don't believe that the QBO has faltered as such. It still looks pretty strong on this chart.

This will be interesting to watch through the winter to see where the bulk of tropospheric westerly winds are - currently situated between30-40ºN.

We certainly need imo precursor Atlantic blocking events so that we are favourably placed for any vortex disruption otherwise any possible SSW may benefit the other side of the globe! My guess is for precursor Atlantic blocking leading to a displacement SSW during January, but with favourable propagation this time (similar to Jan 1987).

GP, do you think that Feb could be slightly below average similar to other El Nino years with northerly outbreaks and followed by a cold March?

Edited November 25, 2009 by chionomaniac

[Glacier Point]

Thanks all for the comments so far.

Good forecast Stewart which I would agree with. I do have a couple of questions though.

1) The easterly QBO faltered somewhat last month ,do you expect this to pick up again as we go through the winter?

2) The current disturbed pattern has prevented ice build up towards svalbad, do you expect this to moderate any cold into northern Europe?

3) You linked the possibility of a weak stratospheric vortex to an increased brewer dobson circulation this year which research suggests is enhanced by CO2 levels, do you think a weaker stratospheric vortex is likely to continue in the coming years?

4) Disruptions to the stratospheric vortex have root causes like blocking high pressure systems in the troposphere, or from jet streams crossing mountain ranges, what format do you think these diruptions will take this winter? Will it be to split the vortex or to push the vortex away or towards the UK?

5) A pick up in the trade winds across the pacific will lift those warm sub surface temperatures, what are you using to determine when this will take place? For example is it when the MJO goes from phase 8 back to phase 1?

1) I have the east QBO running at between 15-20 m/s throughout the winter based on low solar analogues. At present the JMA site shows this about on track:

http://ds.data.jma.g...lat_u30_nh.html

2) Some moderation would appear likely although the main cold should be Siberian in origin so less vulnerable to modification from warm seas. It should be noted that the anologues draw upon similar autumn patterns which would pressumably have impacted that sector of the Arctic.

3) I think the main driver w/r/t to stratosphere and the BDC is the east QBO and solar minima. However, last year's west QBO was noteworthy and we may well be entering a period with much higher stratospheric temperatures reversing the trend over the 1990s and 2000s. The key difference that appears to be showing up is the relative cold in the tropical stratosphere - which may be CO2 related.

4) I've considered the state of ozone going into the winter. The main concentrations would appear to be over the Canadian Arctic and Pacific sectors. This would suggest the PV to be displaced rather than fragmented although tropospheric blocking continues to look to be centred over Greenland and Canada from January onwards.

5) The tropical waves have been working on a roughly 8 week cycle:

http://www.cpc.ncep....vpot_tlon.shtml

I've used this a the main lead on timings and westerly additions - my calculations were westerly wind burst coinciding with the MJO progressing through phases 5-8 late November into December, then fall back in angular momentum early January before a second organised wave starting late January. I'm not sure where the MJO will be at that stage but it's worth noting that the westerly wind bursts have come at different phases of the MJO.

GP, do you think that Feb could be slightly below average similar to other El Nino years with northerly outbreaks and followed by a cold March?

Really not sure about February. It's just too far out with so many variables - much more than normal. The key will be how much angular momentum responds to forcing.

Good luck with the forecast Stewart-

I hope the 78/79 best fit comes in the winner- ahead of 74-

Steve

Thanks Steve, let's hope so.

You going to post up any thoughts for the winter ?

Edited November 25, 2009 by Glacier Point

[Don]

Many thanks for the forecast GP! A superb effort and hope it comes off with a colder January.

[Eugene]

Thanks for that, I may not understand it all, but I certainly appreciate the effort.

I'll have to take the morning off to try and read it fully !!

All you need to know is it's going to be a wet/snowy at times winter for you up on Edge Hill, enjoy the snow and curse the rain

Good luck with the forecast GP, i think February will be another cold month though.

Interesting historical analogues, IB's historical analogues for the winter ahead probably are 1988/89, 1989/90, 1993/1994 and 1997/98

[Mr Maunder]

Thanks GP!

Of particular interest to me is whether the increased NH Ozone levels result in higher stratospheric temperatures this winter (they should do) and whether this translates in to a more negative AO/NAO regime.

I think you can almost trace the decline in negative AO/NAO winters over the last 30 years to the polar decline in Ozone levels, leading to stratospheric cooling and a stronger vortex.

Of course there are many other factors to take in to account. Most relevant, from my point of view, is whether the current El Nino fades away quickly or continues to warm during the next six weeks or so. Despite being very confident quite recently that it would fade away this confidence is diminishing with the lasting strength of the latest Kelvin Wave.

We shall see.

MM

[mcweather]

Thanks for all your hard work GP. Like Steve M I'll take the 78/79 best fit or the 77/78 if we can have another west country blizzard like 18th feb 78

[Polar Side]

Thanks for a very interesting and educational forecast GP.

Can't imagine what this forum would be like if we had another 78/79 !

[VillagePlank]

Good forecast with well written and reasoned views to the future. Well done for the time and effort clearly expended. Good luck!

(Quick question - does anyone have the 500hPA global pressure observations in a tabular, rather than graphical form? Or where it might be found on the web?)

Edited November 26, 2009 by VillagePlank

[KTtom]

Who won the competition to predict the N-W Winter forecast?

[stewfox]

Who won the competition to predict the N-W Winter forecast?

Yes it would be nice to know

[Thundery wintry showers]

Very interesting read indeed- just taken the time to go through it, and it certainly is at odds with some of the popular El Nino winter preconceptions (but then again as stated this is not a "normal" El Nino event!).

For those wondering about the winter of 1965/66, it was quite a snowy one and I believe most of the snow resulted from easterly winds, which were mostly imported across from Scandinavia/W Russia via a Greenland High, rather than deep continental air via the Scandinavian High. This setup first made its presence felt in the third week of November 1965, and recurred at times during a cold January and April, and also briefly affected northern areas in the middle of an otherwise mild February.

There are some hints already at a pattern approaching the above in some model runs but as yet there has been insufficient blocking to the N and NW to enable it to come off.

A word of caution arises from the mention of the 1963/64 and 2002/03 analogues, as those winters were quite cold over the continent with "easterly near-misses" for Britain, suggesting a winter which is not particularly mild but also not particularly snowy. 1979/80 comes with similar caveats- I had a run through the charts for January 1980 recently and around the 5th-9th Britain came extremely close to getting an easterly but it was always just out in the continent. February 1980- a Mushymanrob favourite- was mild, wet, and one of the dullest on record, and had a pattern consistent with what the forecast tentatively hints at for Feb.

1974/75 looks like a "one-off" analogue and so on the current evidence I am thinking that a winter like 1997/98 is looking less likely at the moment (note that 1974/75 had a relatively anticyclonic February, just as 1997/98 did, but the high was in a different place).

[cooling climate]

Yes it would be nice to know

Bump.

[WhiteXmas]

Yeah who did win the competition?

[Weather-history]

A word of caution arises from the mention of the 1963/64 and 2002/03 analogues, as those winters were quite cold over the continent with "easterly near-misses" for Britain, suggesting a winter which is not particularly mild but also not particularly snowy.

Both those winters were preceded by very wet and mild Novembers.

[cooling climate]

Bump.

[cooling climate]

Was the competition canceled. It would be nice to know one way or the other. cheers.