Autumn And Winter Lrfs

[Anti-Mild]

A weak El Nino is good news for our winter prospects because it encourages a southerly tracking Jet Stream leaving the USA, assuming that signals upstream are in favour of cold then it can produce harsh winter weather.

A southerly tracking Jet Stream leaving the US would indicate a -ve NAO set-up = good for us. Unfortunately the current SST's point towards the opposite. That said, that warm anomaly off the US / Canada coast will migrate towards Northern Europe just in time for winter, in theory !

[BLAST FROM THE PAST]

A southerly tracking Jet Stream leaving the US would indicate a -ve NAO set-up = good for us. Unfortunately the current SST's point towards the opposite. That said, that warm anomaly off the US / Canada coast will migrate towards Northern Europe just in time for winter, in theory !

how long/time lag does SST play a part? I seem to remember 4-6 weeks being mentiond and that warm pool has done nothing yet to adversely affect us/ bring zonal pattern. What I have seemed to have picked up is that one signal on its own does not influence, it needs the whole picture to fall into place with some signals being stronger than others. I must admit I am NOT high up on the list [indeed low down ] re SST and tele patterns and its effects. SB, GP, Steve can you help

BFTP

[moses]

I have to say that with all this blocked weather we've been having I was really looking forward to the coming winter. However, early indications suggest an El Nino event for the winter.

Of course it might not happen but the possibility of an Atlantic dominated winter with rain and temperature in double figures is enough to make me depressed.

Disappointment is not what I want from my favourite season.

Karyo

I love cold horrible winters - unfortunately - this gave me bronchitis - twice - last year so let's have a damp mild one !!!

[Damien]

Interesting events today on the NCEP November chart. Very mild air being pumped up admittedly quite far north into Iceland and Greenland aside a cold or very cold Eurasia, although the British Isles and the far North-West of France are also still under this very mild air, largely.

The colder than average "northerly" looking September and warmer than average October with some serious cold air building up to our far north and throughout the Arctic are also quite interesting.

FWIW (as someone will no doubt mention it) the longer range shows some encouraging-looking colder air - and I mean proper "colder" air - pointing down to us from far off the East Coast of Iceland in January, now starting to reach us in February and March. More updates to come.

IRI also publish their next forecast next Thursday - which I believe will be a pivotal forecast for not just this winter but for our future climate after the last one.

Edited August 11, 2006 by Damien

[The Enforcer]

In spite of all the discussions over the last 12 months, I find myself coming full circle and looking at SSTs again:

A year ago:

Now:

The basics are that there are a lot of differences. The North Atlantic is more about greater extremes being present at either end of the scale, with some positional changes, but not a great deal, in my view. On the other hand, the North Pacific paints a very different picture - hardly any high positive anomalies at all and a few negative ones where last year there were high positives. I haven't got the wherewithall to conclude what the specific implications of this are for our winter, but if these differences prevail (when assessed against the situation relative to the same point in the calendar last year) then I would suggest that the forthcoming winter would be very different to its predecessor and if so a few people are likely to be rather disappointed to say the least.

Edited August 11, 2006 by The Enforcer

[BLAST FROM THE PAST]

Enforcer

Its a very good post which deserves a response from the tele/SST skilled band. Personally it looks a decent set up to me and more 'action' may be experienced by our shores ie southerly jet potential? I think SBs autumn forecast covers some points rather well and has probably touched on this.

BFTP

[Weather-history]

As regards to Daniel's mild, dry October --> cold winter theory in the models thread

Does a mild, dry October increases the chances of the following winter being colder than average? I let you decide

1995 Oct 12.9 Rain 52.0mm --------> winter 1995-96 below average

1985 Oct 11.0 Rain 46.7mm --------> winter 1985-86 below average

1978 Oct 11.9 Rain 17.2mm --------> winter 1978-79 severe

1969 Oct 13.0 Rain 17.5mm --------> winter 1969-70 below average

1965 Oct 11.0 Rain 33.9mm --------> winter 1965-66 close to average notable cold spells

1908 Oct 11.8 Rain 56.2mm --------> winter 1908-09 slightly below average

1861 Oct 11.8 Rain 48.2mm --------> winter 1861-62 close to average

1809 Oct 10.2 Rain 10.9mm --------> winter 1809-10 slightly below average#

1806 Oct 10.6 Rain 41.9mm --------> winter 1806-07 slightly above average#

1793 Oct 11.3 Rain 52.9mm --------> winter 1793-94 fairly mild#

1790 Oct 10.3 Rain 56.9mm --------> winter 1790-91 fairly close to average#

1781 Oct 10.6 Rain 8.8mm ---------> winter 1781-82 fairly close to average#

1776 Oct 10.2 Rain 49.6mm --------> winter 1776-77 fairly cold#

1774 Oct 10.3 Rain 40.9mm --------> winter 1774-75 fairly mild#

# For that time period those Octobers could be considered mild.

The results are fairly mixed to be honest, however there is no especially mild winters (>5 CET) in those stats.

The "mild September doesn't favour a cold winter" theory

September CET of 15.0 or greater

2005 15.2 Winter CET: 4.1

1999 15.6 Winter CET: 5.4

1961 15.2 Winter CET: 3.6

1958 15.1 Winter CET: 3.6

1949 16.3 Winter CET: 5.1

1929 15.3 Winter CET: 4.6

1898 15.2 Winter CET: 5.8

1865 16.3 Winter CET: 5.3

1825 15.1 Winter CET: 3.8

1795 16.0 Winter CET: 6.2

1780 15.6 Winter CET: 3.4

1779 15.2 Winter CET: 1.4

1760 15.7 Winter CET: 5.8

1750 15.2 Winter CET: 3.2

1731 15.3 Winter CET: 4.7

1730 15.3 Winter CET: 2.5

1729 16.6 Winter CET: 4.6

1708 15.0 Winter CET: 1.2

1678 15.0 Winter CET: 1.0

Winters with CET <2: 3

Winters with CET between 2 and 3: 1

Winters with CET between 3 and 4: 5

Winters with CET between 4 and 5: 4

Winters with CET between 5 and 6: 5

Winters with CET >6: 1

So there's 9 winters with a CET of less than 4C and 10 winters with a CET of greater than 4C

So does a September with a CET>15C lead to a mild winter?

Well it depends from which year you are observing from, in recent times you would say it lead to a mild winter but pre 1760 you could say it favoured a cold winter

Inconclusive, I would say

----------------------------------------------------------------------------------------------------------

However, the "very warm June doesn't favour a mild December" is interesting

There have been 26 Junes with a CET of 16 or greater, 12 have been followed by a December of less than 3C

21 have been followed by a December that was below the 1961-90 average

24 have been followed by a December that was below the 1971-90 average

Only 2 were followed by a December that had a CET of above 5C: 5.4 and 5.8

Edited August 12, 2006 by Mr_Data

[chilly milly]

Wow an awful lot of info there Mr Data, but very interesting thank you.

I find it hard to believe that a CET in one month can have a corresponding effect on a CET in a later month as I think it all boils down to the chaos theory.

Mind you seeing as this June was very warm from what i recall, then I'd love to see a cooler December this year. Those 2 Decembers that had the CET of above 5C, were they recent or way back when?

[Weather-history]

Mind you seeing as this June was very warm from what i recall, then I'd love to see a cooler December this year. Those 2 Decembers that had the CET of above 5C, were they recent or way back when?

1781 and 1826

[johnholmes]

hi

loads of fascinating info there as usual Mr Data

tks for all that

[Damien]

Today's NCEP shows easterlies *somewhat* coming back in December though the winter is still mild. August is now also slightly less cool, certainly in Ireland.

In the longer term, January is now also slightly cooler from and for the East, as is February from the North and East. March is also expected to be a below average month, albeit just marginally, even though it's in far FI. Certainly a very weakly positive NAO winter ahead looking by these charts. A repeat of 2000/01? I'd take that any day!

Must admit I am in the mood for winter after going to the Pennines today.

[Thundery wintry showers]

A weak El Nino is good news for our winter prospects because it encourages a southerly tracking Jet Stream leaving the USA, assuming that signals upstream are in favour of cold then it can produce harsh winter weather.

Here are some winters since 1950 which had a weak El Nino throughout:

2005

1993

1980

1978

1964

1959

Only 1959 and 1993 did not observe a positive PNA pattern, only 2005 did not have a below average month however it did have a severe wintry spell at the end of February.

Not many of those winters were especially snowy though:

2004/05: mostly mild and dry, brief wintry spell in N & W around Christmas, lots of wet snow late February, severe in certain regions of the country

1992/93: near average to fairly mild and largely snowless, only snow of note being in N Scotland on 15-16 December, the Braer Storm of 10-13 January and a northerly at the end of February

1979/80: average snow-wise, but probably the least snowy winter of the 1978-87 period

1977/78: generally snowy in January & February

1963/64: cold and dry, with little snow

1958/59: cold and dry, a wintry January in the north but almost entirely snowless in December and February

So not an especially mild set of winters, but with the exception of 1978 none were snowy.

[The Enforcer]

A repeat of 2000/01?

Yuk. Crap again.

So not an especially mild set of winters, but with the exception of 1978 none were snowy.

Sounds like 2005/2006 all over again.

[Damien]

Just out of interest:

August:

September:

October:

November:

A wet start to December if anything else looking at the "actual temperature" chart:

http://ecpc.ucsd.edu/imagedata/NSMD/DRF/FW...200.week_16.gif

for comparison:

http://ecpc.ucsd.edu/imagedata/NSMD/DRF/FW...200.week_16.gif

so still below average overall(!?). :blush:

IRI (British Columbia) update later this week. Holding my breath for this one. :lol:

[Schnee]

Forgive me, (novice asking stupid questions) but what do those charts show????? :blush:

I'm particulally interested in people's views for late September and early October.

[Anti-Mild]

Forgive me, (novice asking stupid questions) but what do those charts show????? :blush:

I'm particulally interested in people's views for late September and early October.

It shows cooler than average conditions for October, November and December for the South.

[SMU]

how long/time lag does SST play a part? I seem to remember 4-6 weeks being mentiond and that warm pool has done nothing yet to adversely affect us/ bring zonal pattern. What I have seemed to have picked up is that one signal on its own does not influence, it needs the whole picture to fall into place with some signals being stronger than others. I must admit I am NOT high up on the list [indeed low down :blush: ] re SST and tele patterns and its effects. SB, GP, Steve can you help

BFTP

Hi BFTP- Its all about time lag & Rate of change...

SST's are generally considered to be a factor in effecting patterns down the line by 4-6 weeks, obviously the rate of change of anomalies 'should be proportional to the time span of impact onto prevailing patterns-

However it is as not as clear as that otherwise LRF forecasting would just be about SST's & time lag- Forecasters must also consider other factors influencing the weather, they all have a part to play & these have propergation times -

For instance another pick of the Winter forecasts was the sudden Stratospheric warming events that tied in with the Negative AO-

Remember you have SST'a Influencing the weather, Stratospheric Temps & teleconnections - Some are cause, Some are effect- going into Winter its knowing which drives which...

S

Edited August 14, 2006 by Steve Murr

[BLAST FROM THE PAST]

Hi BFTP- Its all about time lag & Rate of change...

SST's are generally considered to be a factor in effecting patterns down the line by 4-6 weeks, obviously the rate of change of anomalies 'should be proportional to the time span of impact onto prevailing patterns-

However it is as not as clear as that otherwise LRF forecasting would just be about SST's & time lag- Forecasters must also consider other factors influencing the weather, they all have a part to play & these have propergation times -

For instance another pick of the Winter forecasts was the sudden Stratospheric warming events that tied in with the Negative AO-

Remember you have SST'a Influencing the weather, Stratospheric Temps & teleconnections - Some are cause, Some are effect- going into Winter its knowing which drives which...

S

Thanks Steve

It seems that is what I was getting at I think but many thanks for the clarification as my explanation was pretty basic :blush: . I believe it is beginning to sink in but I am a long way off from being able to read them signs but enjoy the learning curve..should help to keep these grey cells from greying further

BFTP

[summer blizzard]

1956 - Neutral

1963 - Strongly negative

1979 - Neutral

1982 - Moderately negative

1985 - Neutral

1986 - Weakly positive

1991 - Weakly positive

1996 - Weakly negative

I have picked eight of the coldest winters of the last 50 years, in order to see whether or not we really should be aiming for that neutral QBO value during winter.

Here are my classifications:

Neutral - Value between 0 and 5 or 0 and -5

Weak - Value between 5 and 10 or -5 and -10

Moderate - Value between 10 and 15 or -10 and 15

Strong - Value above 15 or -15

In conclusion, i would prefer to see a weakly positive to weakly negative value, therefore a neutral QBO value is preffered for a colder winter bar the exeptional cases of 1963 and 1985.

[Stratos Ferric]

1956 - Neutral

1963 - Strongly negative

1979 - Neutral

1982 - Moderately negative

1985 - Neutral

1986 - Weakly positive

1991 - Weakly positive

1996 - Weakly negative

I have picked eight of the coldest winters of the last 50 years, in order to see whether or not we really should be aiming for that neutral QBO value during winter.

Here are my classifications:

Neutral - Value between 0 and 5 or 0 and -5

Weak - Value between 5 and 10 or -5 and -10

Moderate - Value between 10 and 15 or -10 and 15

Strong - Value above 15 or -15

In conclusion, i would prefer to see a weakly positive to weakly negative value, therefore a neutral QBO value is preffered for a colder winter bar the exeptional cases of 1963 and 1985.

SB,

Not sure that analysis stacks up. You also need to look at the relationship between QBO values (whatever they are) and warm winters. It may well be there's no pattern at all, and I have to say, looking at the above, there doesn't appear to be.

[Tim]

I'm still going for a very mild and stormy 89/90 winter.

This summer has been so 89 like to me (way above average except August) so I just have a gut feeling that we'll get a similar winter

[Guest Mike W]

I suppose some people won't mind that as long as we get a similar winter to 90/91 the winter after next, which I know would be alot harder to get.

Edited August 16, 2006 by Mike W

[beng]

I'm still going for a very mild and stormy 89/90 winter.

This summer has been so 89 like to me (way above average except August) so I just have a gut feeling that we'll get a similar winter

Always possible Tim - but a couple of reasons I don't think we'll see it this year - 89/90 was at or near the peak of the solar cycle and sea surface anomolies were very different:

http://www.osdpd.noaa.gov/PSB/EPS/SST/data....90.anomaly.gif

Back in 89/90 there was a developing La Nina in the pacific (quite a potent one I believe) - and also the cold North Atlantic, combined with a warm Southern North atlantic - classic indicator of a positive NAO.

This winter we may have a weakish El Nino, and I suspect a warm North Atlantic (50-60 degrees latitude), combined with a cooler (relative) southern north Atlantic.

http://www.osdpd.noaa.gov/PSB/EPS/SST/data...t.8.15.2006.gif

Okay so we're still 3-4 months away from Winter and there's plenty of time for the sea temp profile to change as we go through Autumn, but right now I'd say we're looking at more blocking this winter.

[ScandiHigh]

I'm still going for a very mild and stormy 89/90 winter.

This summer has been so 89 like to me (way above average except August) so I just have a gut feeling that we'll get a similar winter

I pray to God to not have a winter like that. In Oslo were i live february 1990 set a record for a winter month that I hope never will be beaten(even with GW):

A mean temperature of 3,4 C (7,4 above 61-90 mean). Forget frost and snow in Britain and even in most parts of Norway with that kind of winter.

[Damien]

With mild now even starting to retreat in November and January, the dream is alive!!!

http://www.cpc.ncep.noaa.gov/products/peop...bT2mMonNorm.gif

http://www.cpc.ncep.noaa.gov/products/peop...bT2mSeaNorm.gif

(Shame we can't trust these charts no matter what they are showing. :lol: )