Autumn 2007 Forecasts

[Glacier Point]

A couple of thoughts on likely key players this Autumn:

1. Global Average Angular Momentum (GLAAM) levels have reached very low values this Summer. This in effect makes the whole atmospheric in a very slow moving state. This average is largely defined by the Northern Hemisphere where the anomalies have been greatest. Whilst not directly correlated with high latitude blocking, reanalysis of Autumns with a -ve GLAAM suggests positive height rises across the polar field.

Panel 1: 30mb zonal wind anomalies this Summer showing -ve wind (momentum) anomalies across the entire northern hemipshere.

Panel 2 : Years when the GLAAM was at low levels during the Autumn

Panel 3: Reanalysis of Autumn years zonal wind anomaly suggesting continued blocking and low upper level flow

2. The Quasi Biennial Oscillation (QBO) has rapidly attained highly -ve values indicative of upper level strong easterly winds across the Equator. For comparison, I've charted similar years for easterly cycle QBO which started in the Spring.

Panel 4: QBO comparison

This makes a record -ve QBO value late October / November a distinct possibility. Linear correlation to the QBO suggests a strong link between QBO and mid Atlantic High in particular (remember the correlation is inverse so blue / purple equates to higher pressure).

Whilst not strongly correlated to the QBO, blocking has often occured during easterly phases of the QBO.

Panel 5: QBO linear correlation to 500 mb geopotential height anomalies

3. La Nina continues to threaten, and with a strong easterly wind over the Equator, we have ideal conditions for upwelling of anomalously cold sub-surface water. However, the modelling has consistently over-cooked La Nina and unexpected westerly surface winds have surpressed cold water development. La Nina has taken on a rather sporadic look, but I think weak to moderate La Nina is a possibility. This is probably too weak to influence Atlantic pressure anomalies.

4. Sea Surface Temperature Anomalies favour height rises to our west and north. Reanalysis of all years with a similar 'footprint' of cold anomalies to the west Atlantic and warm anomalies to the north suggests the following response:

Panel 6:500 mb geoptential height anomaly for years with a similar SSTA

Conclusion:

• Polar field to continue to see height rises with Arctic Oscillation phased between 0 and -1.
  
• La Nina to attain moderate status by November, but too weak to influence Atlantic pressue patterns.
  
• Climatic trend likely to add 0.25C to overall temperature.
  
• SSTA pattern to provide greatest amount of forcing, adjusted slightly for forcing from strong easterly QBO.
  

Panel 7: Forecast surface pressure anomaly pattern based on Atlantic SSTA adjusted for strong eastery QBO and tendency for height rises on the mid Atlantic.

• Lots of high pressure to our west and north with an increasing trend for a -ve NAO pattern as the Autumn progresses.
  
• October likely to be the most unsettled month with analogues suggesting weakening of the block to our west.
  
• High pressure to remain in place over Greenland with continued polar trough extending into Scandinavia.
  
• Overall CET close to average and drier than average.
  

[summer blizzard]

Glacier Point, i agree wsomewhat with your forecast, howerever i must say that i dont believe La Nina will reach moderate strength, especially by November, though if it did reach moderate (MEI value of -1>), then it would probably account for a third of the pattern, so a pretty large effect.

[SNOW-MAN2006]

Here it is guys my AUTUMN 2007 forecast, enjoy B)

Autumn_2007_Forecast.doc

SM06

[Lettucing Gutted]

Here it is guys my AUTUMN 2007 forecast, enjoy

Autumn_2007_Forecast.doc

SM06

Just seen your autumn forcast Snowman. October and November look mild and stormy. Doesn't bode well for a better, colder winter this year.

[The PIT]

Well lets get my wrong.

September: A fairly settled month with above average Sunshine and below average rainfall. High Pressure close to the West of the UK mainly but migrating at times to the east giving short brief warmer spells. CET above average. Scotland and NI will be effected by the Atlantic systems at times but still likely to have below average rainfall. NE may also be effected by fronts as they pass down the North Sea into Europe.

October Will see the Atlantic systems beginning to get rolling and it will be windy at times with the first real storms of the Autumn coming through. Rainfall average to above average as will be the temps for the month overall. Likely to see the return of High Min curse of recent years as night time temps are held up by cloud and strong winds.

November probably quieter than October but still a mild month probably overall. Unlikely to be any Snow bar the hills of Scotland. A quieter spell possible around mid month with more wide spread fogs before the Atlantic ramps up again ending Autumn on the mild side with the prospects of another mild Winter on the cards. Overall above average temp wise rainfall around average. Sunshine average to below average.

Lets see how far off I am.

Here it is guys my AUTUMN 2007 forecast, enjoy

Autumn_2007_Forecast.doc

SM06

Nicely laid out but doesn't display properly in word 2003 with some of the text disappearing out of view under the text boxes.

Edited August 30, 2007 by The PIT

[Lettucing Gutted]

How cool does this autumn and December have to be to keep the 2006 warmest annual C.E.T record intact?

It will be frightening if the annual C.E.T record falls every year.

Edited August 30, 2007 by Craig Evans

[BLAST FROM THE PAST]

How cool does this autumn and December have to be to keep the 2006 warmest annual C.E.T record intact?

It will be frightening if the annual C.E.T record falls every year.

PM Mr Data or SF as they have calculated it I believe.

BFTP

[BLAST FROM THE PAST]

OK

Sept - early part dominated by HP minly to our west but moving over us giving a pleasant warm spell round 6-10. HP will then build to our north and cooler and more unsettled conditions will follow, indeed a wet latter half of the month. CET close to or just below average.

Oct - I expect October to have a southerly trackng jet with LP after LP giving us a darn good soaking. CET average but wetter than average.

Nov - A northerly and easterly dominated month with northern blocking the theme. Fairly calm with frost and fog being a problem. Latter half of the month will become more unsettled as the Atlantic makes a play and interestingly I think early snowfalls are likely. However, getting milder towards the end as La Nina has strengthened and the Atlantic takes over. CET 1c below average.

BFTP

[Gavin P]

Blast, I agree entire with your thoughts regarding November. I think we stand a very good chance of some early snow this November.

Not sure I agree about La Nina, though. I think its getting to the point, where it may just start to fizzle by the end of the year. It'll be interesting to see what happens.

[BLAST FROM THE PAST]

Blast, I agree entire with your thoughts regarding November. I think we stand a very good chance of some early snow this November.

Not sure I agree about La Nina, though. I think its getting to the point, where it may just start to fizzle by the end of the year. It'll be interesting to see what happens.

Hi Gavin

you may be right but I think Nov/Dec will see it at its peak.

BFTP

[Gavin P]

I probably agree with that. The question will be what level does that "peak" reach? Will it be a really strong peak? Or a weaker peak? I'm honestly not sure.

[Cookie]

lots of wind I hope

[kold weather]

I personally can't see a strong peak, I've always said a wreak La nina forming during Autumn and i still think thats likely but I don't think its going to get below 1C below the average out there making it a weak La nina. at that strength it shouldn't have much impact on our set-up, if it gets to moderate then it may start to have an effect if it can over-rule the other synoptic set-up tohugh we have near record breaking QBo and GLAAM so La nina might have to get upto borderline strong for it to have a major impact IMO and that is very unlikely right now.

Edited August 30, 2007 by kold weather

[BLAST FROM THE PAST]

I personally can't see a strong peak, I've always said a wreak La nina forming during Autumn and i still think thats likely but I don't think its going to get below 1C below the average out there making it a weak La nina. at that strength it shouldn't have much impact on our set-up, if it gets to moderate then it may start to have an effect if it can over-rule the other synoptic set-up tohugh we have near record breaking QBo and GLAAM so La nina might have to get upto borderline strong for it to have a major impact IMO and that is very unlikely right now.

Indeed KW that mbe the case as it has struggled but maybe signs now of movement in strength...and good to see the Mr AO sig.

BFTP

[summer blizzard]

I personally can't see a strong peak, I've always said a wreak La nina forming during Autumn and i still think thats likely but I don't think its going to get below 1C below the average out there making it a weak La nina. at that strength it shouldn't have much impact on our set-up, if it gets to moderate then it may start to have an effect if it can over-rule the other synoptic set-up tohugh we have near record breaking QBo and GLAAM so La nina might have to get upto borderline strong for it to have a major impact IMO and that is very unlikely right now.

I personally agree with that, obviously this is subjective, but if my predicted anologue based values come off this Autumn, then the earliest we will see any effect from La Nina is November, and that is only because the QBO will have weakened sufficiently not to dominate the pattern on its own.

Also, expect the peak to occur aroudn February/March.

[Paul]

Netweather Autumn and early Winter forecast is now online

http://www.netweather.tv/index.cgi?action=longrange;sess=

[Stratos Ferric]

How cool does this autumn and December have to be to keep the 2006 warmest annual C.E.T record intact?

It will be frightening if the annual C.E.T record falls every year.

That scenario is hugely improbable: the general variability in annual temperature at present is running at around 0.8C - narrow by historical standards. The annual mean change in temperature is still less than 0.1C per year, and that during a period of rapid warming just recently. I doubt we're going to exceed last year's mark now, even though we're around 4C cumulatively ahead of where we were entering September 2006. If we spread that "allowance" evenly across the remaining months, the outturns would rank 6th, 12th, 70th and 73rd in the all time lists for their own months: still an unusually warm run. I wouldn't yet rule it out of hand because the SST signature is changing markedly now in the Atlantic, but on the other hand there's a Nina forming in the Pacific. As I've said elsewhere, a more interesting "spread" now is the previous high water mark of around 10.65C. We could afford to be cooler than four of the last five S-D series and still "bag" no.2 in the all time list.

[Don]

Well, my view about this coming Autumn is that it will be much the same as the last few - mild or very mild with variable rainfall.

Also, Winter 2007/08 is looking like being another poor one ATM (if you like it cold) according to certain long range weather forecasts. I know it's really too early to tell at this stage, but I know where I would lay my bets for this coming Winter.

B)

[Cymru]

Well, my view about this coming Autumn is that it will be much the same as the last few - mild or very mild with variable rainfall.

Also, Winter 2007/08 is looking like being another poor one ATM (if you like it cold) according to certain long range weather forecasts. I know it's really too early to tell at this stage, but I know where I would lay my bets for this coming Winter.

B)

I too am going for a warm Autumn and mild winter. I doubt we will ever see anything approaching 62/63 again in our lifetimes, though I would be happy to be proved wrong.

[Roger J Smith]

I think September will be a fairly warm month (said 15.8 in the CET thing but above 14 at least), becoming quite stormy in the last third but mainly SW'ly at that point, leading to a very blustery October this year, probably coming in close to normal for temperature (let's say 10.8 ) but with a lot of wind and rain, then November could be highly variable as I think there is some potential here for an earlier winter set-up given the somewhat lower ocean temps and also the projection of a strong ridge over the western Atlantic by late autumn. So for November I would project a mean somewhat below the long-term and quite below the recent averages near 4 or 4.5 C, but with a lot of variations. That scenario should allow one wintry episode, you would think -- so possibly a month rather like Nov 2005.

If all that were correct then December would have to be very mild to catch the annual record. I estimate on the basis of the above verifying, it would need to be at the record or above (8 ) and I don't see that quite happening. So the chances for a record warm year seem to be dependent on each of the next four months running 1-2 C above normal. Could happen, probably won't.

Edited September 1, 2007 by Roger J Smith

[Damien]

Even though I don't really trust it, just seen the NOAA forecast for the next few months/the full winter (by now). It really is looking dire if the Netweather winter forecast is based on that.

http://www.cpc.ncep.noaa.gov/products/peop...uT2mMonNorm.gif

http://www.cpc.ncep.noaa.gov/products/peop...uT2mSeaNorm.gif

Let's see what the ECPC GFS update brings in a few days/late next week (hopefully).

To me, at the moment, on those NOAA charts, the pattern is looking all too similar to recent years at the precise moment - a very cool/cold October across most of Northern Eurasia/Europe-Russia, with a followed by a significantly above average and south-south-westerly winter. :lol:

But, fortunately we all know what the track record of the NOAA CFS is like is the long-range forecasting field. :lol:

[Paul]

Yep, it nailed this summer from April onwards, showed the high rainfall for June and July 1-2 months in advance and was absolutely spot on for August at least 2-3 months in advance

[Damien]

ENSO:

http://www.cpc.ncep.noaa.gov/products/peop...nino4SSTMon.gif

http://www.cpc.ncep.noaa.gov/products/peop...nino4SSTSea.gif

[damianslaw]

I don't pay any real attention to long range forecasts, take this years Met office forecast for this summer one of the hottest likely on record! what a load of rubbish, yes sometimes they do get it right like winter 05/06 (though even then it didn't quite turn out as cold as first anticipated)...

This summer is a real lesson too many who take long range forecasts as gospel......, the safe option for winter today will always be to forecast another mild one, just like a warm one for summer...

[Damien]

This summer is a real lesson too many who take long range forecasts as gospel......, the safe option for winter today will always be to forecast another mild one, just like a warm one for summer...

That said NOAA had a good summer, according to Paul (the NW forecasts are based on their output, yes?). If so, gulp. But the winter forecast has been "back-forth, back-forth" "cold-mild, cold-mild" for some time now - though the overall consensus seems to be a slightly cooler than average start followed by with a well above average end. So again as I said in the other thread maybe a very 2001/02-type character to this winter starting with a very 2001-like autumn(?). Certainly this summer *has* resembled 2001 in *some* aspects IMHO (mainly in it's poor end than anything else).