MetO to call a positive / negative NAO for winter 2008-09?

[BLAST FROM THE PAST]

Yes, I've seen plenty of posts on this as well. There may be a slight correlation with regards recent years, but chances are you won't find a correlation if you take the entire record.

The cold wet September, warm dry October theory worked very well prior to the cold 1995/96 winter, but not, for example, prior to that of 1981/82 with October 1981 having been very cool and wet, although quite sunny.

Indeed there'll always be correlations such as Oct 85 folowed by the Great Feb 86 but as TWS says there won't be one of significance if the whole record is looked at.

Don't woory too much about oranges at this stage.

BFTP

[johnholmes]

no one, individual or centre, has ever found any correlation between autumn-winter or any other seasonal link. Sure, now and then one season APPEARS to show it. However, that is not a statistically robust way of showing a link. ALL events or non events must be shown and there has never been any proof of this.

[Gavin P]

Personally, I think dry Octobers (be they warm or not) can be an indication

that the jet stream is weaker than normal, and may carry on being so until winter. When you look at uniquely dry October years such as;

1962

1969

1978

1985

1995

Were all followed by cold winters. However, this is not the be all and end all. ENSO and Atlantic SST's are much more important. For instance, last year we had a dry October, but a cold winter was a non starter with the La Nina event that was going on. Similarly, there have been a lot of cold winters without dry Octobers, such as 1947 and 1981/82.

Edited June 1, 2008 by Gavin P

[johnholmes]

yes Gavin, that is precisely why we cannot use dry Octobers as an indicator for winter, you quote the two coldest winters in the 20th century

1947 did NOT fit that criteria

1963 did

[damianslaw]

I tend to take more notice of conditions during late November and early December as a potential sign for the rest of the winter. This particular period normally sees the atlantic reach its annual maxim in terms of intensity, a quiet atlantic during this period may suggest that the atlantic will remain quiet through the winter.

[Thundery wintry showers]

Even that relationship is fraught with danger unfortunately. The period late November-early December 1989 was very blocked, for instance, but as soon as January 1990 set in, so did the westerlies.

As an example of how fickle winter patterns can be, and how they can change at the flick of a switch, take 1996/97 for example- frequent northerly and north-westerly winds in November 1996 with snow for some, a blocked easterly December, a blocked anticyclonic January, then rampant westerlies in February, almost on a par with the exceptionally westerly February of 1990.

In recent times 2004/5 was quite a contrasting case with lots of blocking in late November/early December, a strongly westerly phase from mid December to late January (though briefly cool zonal around Christmas), and then increasingly blocked weather again through February.

[North-Easterly Blast]

2001-02 is another example too of a pear shaped winter. December 2001 was very anticyclonic and generally cold with some north-north-westerly spells around Christmas, and a cold anticyclonic spell into the New Year but mild zonality returned by the second week of January and the rest of winter was horrendously mild.

Yes, February 1997 was a real stinker after much colder conditions in December and January - very similar to the winter of 1944-45.

Even getting a quiet Atlantic does not guarantee severe cold conditions or at least anything exciting during winter. In 2005-06 the blocks were not often in a position to deliver anything severely cold that winter despite a quiet Atlantic throughout. In 1991-92 all we got was surface cold under high pressure at times and never deep cold Arctic air.

The key for me at least in winter, if the Atlantic is active, why can the zonal pattern not be cold zonal like January 1984? The key that month was that there was fairly frequent high pressure areas over north-eastern Canada which helped to inject colder air into the zonal flow and the zonal flow tracked more NW-SE, and we did not get the sort of secondary depressions forming to our NW that cut off the cold polar maritime NW'lies after only a day or so.

Will we ever see this sort of true cold zonality ever again?

Edited June 2, 2008 by North-Easterly Blast

[Weather-history]

yes Gavin, that is precisely why we cannot use dry Octobers as an indicator for winter, you quote the two coldest winters in the 20th century

1947 did NOT fit that criteria

1963 did

October 1946 was a pretty dry month only about 46% of the 1961-90 October rainfall average and it was drier than last October.

Infact it was only 2mm wetter than October 1962.

Edited June 2, 2008 by Mr_Data

[johnholmes]

are you saying Kevin that a dry October = a cold winter?

show me every dry or even very dry October and the subsequent winter. if you have about 70-80% that fit dry October/cold winter then I'll have another look!

[summer blizzard]

are you saying Kevin that a dry October = a cold winter?

show me every dry or even very dry October and the subsequent winter. if you have about 70-80% that fit dry October/cold winter then I'll have another look!

Jhon, weve been through this many times in the past few years and no link has been found, however there is a statistical link (70%+) between a positive NAO during October, and a negative NAO the following winter, or visa versa, now because a positive NAO would most likely give warmer weather, i believe that there is a half truth to the warm October/cold winter theory.

[Thundery wintry showers]

I'm pretty certain that there are counter-examples:

October 1947, Winter 1947/48- average to fairly mild, not much snow until late February

October 1959, Winter 1959/60- average to fairly mild (though some significant snow at times in Jan & Feb)

October 1971, Winter 1971/72- mild, with only one significant snow event (the easterly freeze-up at the end of January)

October 1979, Winter 1979/80- average to fairly mild, the least snowy winter of the 1978-87 period.

I don't think Kevin was trying to suggest that dry October = cold winter though (indeed I've seen him post on the contrary), I think he was just correcting the notion that 1947 didn't fit the criteria.

[Glacier Point]

The key focus for me this year will be what factors are likely to lead to increased storminess and upper level troughing over the continental mountain ranges of Asia and North America. Why ?

These events I believe are a major factor in producing wave-breaking of the stratospheric jet resulting in warming events, such as that observed in February this year and which went on to influence the pattern, and still does so now. As we know from bitter experience, the SSTA in the North Atlantic can be as favouable as it likes, but if it does not have the support of a -AO, then it cannot realy influence the long term pattern.

The answer to the question, I believe, lies in the tropics and upper levels, the Brewer-Dobson Circulation being the possible mechanism linking the two. It could just be coinicidence that all major stratospheric warming events occured when the tropics were active and the QBO was in a weak state (both easterly and westerly). Very much a research project for the late summer and autumn I think.

Edited June 2, 2008 by Glacier Point

[johnholmes]

I look forward to reading your output with conclusions GP

[Weather-history]

I don't think Kevin was trying to suggest that dry October = cold winter though (indeed I've seen him post on the contrary), I think he was just correcting the notion that 1947 didn't fit the criteria.

Thanks TWS, yes that was what I was meaning, that actually October 1946 was a dry October. It is drier than any October since 1978.

Octobers 1916, 1928 and 1939 were wet ones that were followed by very cold winters. October 1939 was a cold October, incidentally.

[johnholmes]

Jhon, weve been through this many times in the past few years and no link has been found, however there is a statistical link (70%+) between a positive NAO during October, and a negative NAO the following winter, or visa versa, now because a positive NAO would most likely give warmer weather, i believe that there is a half truth to the warm October/cold winter theory.

oh I know we have been through it pal, it crops up each year and no one has yet proved any link whatever, certainly not sufficiently robust enough to be able to use as even part of forecasting 3 months ahead.

I would be interested in your data re +/-ve signals October into winter though.

I'm always open to someone prooving a theory with some validity.

I'll wait for your data to have a look through.

thanks

Thanks TWS, yes that was what I was meaning, that actually October 1946 was a dry October. It is drier than any October since 1978.

Octobers 1916, 1928 and 1939 were wet ones that were followed by very cold winters. October 1939 was a cold October, incidentally.

No I did not for a moment think that is what you meant Kevin, so thanks to Ian and yourself for clarifying it.

I'll be interested to read what comes from the +/-ve idea from SB in terms of data. I'd love to see some usable link if its possible even with only a moderate % chance of success.

Edited June 2, 2008 by johnholmes

[North-Easterly Blast]

I'm pretty certain that there are counter-examples:

October 1947, Winter 1947/48- average to fairly mild, not much snow until late February

October 1959, Winter 1959/60- average to fairly mild (though some significant snow at times in Jan & Feb)

October 1971, Winter 1971/72- mild, with only one significant snow event (the easterly freeze-up at the end of January)

October 1979, Winter 1979/80- average to fairly mild, the least snowy winter of the 1978-87 period.

I don't think Kevin was trying to suggest that dry October = cold winter though (indeed I've seen him post on the contrary), I think he was just correcting the notion that 1947 didn't fit the criteria.

I am not entirely sure that winter 1979-80 was the least snowy winter of the 1977-87 period. Apart from the April 1981 blizzards, the winter of 1980-81 in itself had relatively little snow. There was a bit of snow in late November and a snow event in many areas around the 22nd / 23rd February; these are the only noteworthy snowfalls of the 1980-81 winter.

[Thundery wintry showers]

There were also some potent, albeit short-lived, northerlies in January 1981, with the biggest one providing a dumping in Glasgow around midmonth.

As far as I'm aware 1979/80 had minor snow events at the end of December and on occasion in January, but the only significant snow of the winter quarter was at the beginning of February before mild cloudy south-westerlies set in.

[Gray-Wolf]

C'mon guys! Though a bit of the white stuff is fun the current fuel price hikes, food price rises would leave many more folk in energy poverty should we face a cold winter this coming year.

Being a vainglorious nation we rarely use 'hypothermia' as a cause of death on documentation (wouldn't look good on our 'records'...kinda like calling suicide 'accidental death') so we must check our past records for old folk dying of kidney failure/stroke/heart failure during protracted cold periods.

Yes, we can have some 6hr frontal snow events but winters like the 60's or 80's? no thank you!

Anyhoo, with NOAA being split over a moderate El Nino/return to La Nina and the pole set to melt over summer we can probably expect the unexpected. Personally, with the Cathrite releases scheduled for the Siberian/Eurasian permafrost this summer we may be in for an Aussie Christmas....barbie on the beach anyone?

[Lettucing Gutted]

Anyhoo, with NOAA being split over a moderate El Nino/return to La Nina and the pole set to melt

Oh not another moderate El Nino...

[Stargazer]

As far as I can see, El Nino/La Nina's effect on our climate seems to be:

Moderate La Nina: UK gets a mild westerly dominated winter (with a small chance of something different)

Slight La Nina: UK gets a mild westerly dominated winter (with a small chance of something different)

ENSO neutral: UK gets a mild westerly dominated winter (with a small chance of something different)

Slight El Nino: UK gets a mild westerly dominated winter (with a small chance of something different)

Moderate El Nino: UK gets a mild westerly dominated winter (with a small chance of something different)

I'll get my coat...

Edited June 3, 2008 by Stargazer

[BLAST FROM THE PAST]

Thought I'd bring this back to the forefront as their release must be due now?

BFTP

[NorthantsSnow]

I don't have a clue about NAO/Nina/Nino or whatever. I just keep my eyes pealed on this chart every now and then:

http://www.cpc.ncep.noaa.gov/products/peop...es/euT2mMon.gif

Early indications for December look to be v cold across Europe according to that - why is that I wonder?

Yes people - if there's a straw worth clutching, I'm so on it. :o

Edited July 7, 2008 by NorthantsSnow

[kippure]

I don't have a clue about NAO/Nina/Nino or whatever. I just keep my eyes pealed on this chart every now and then:

http://www.cpc.ncep.noaa.gov/products/peop...es/euT2mMon.gif

Early indications for December look to be v cold across Europe according to that - why is that I wonder?

Yes people - if there's a straw worth clutching, I'm so on it. :o

I dont know... but like you i want a 100% chance of a white christmas................................

[Nick L]

Wow 0.5c below average, that's like being stuck in a freezer compared to the past 2 winters!

Anybody know the exact date when the Met Office release their initial predictions?

[Stargazer]

Hate to dampen the enthusiasm, but to me this chart appears to show 6 months of remarkably close to average temperatures for the UK...think December 2007.

Edited July 7, 2008 by Stargazer