257 replies to this topic

[CreweCold]

What clues/signs can be gathered from the weather during the autumn months as to how the following winter may pan out. For example, sea surface temperature anomolies and weather patterns during the coming months......

Also how do these factors shape up in the context of this coming season?

[Isolated Frost]

CreweCold, on 18 October 2011 - 17:06 , said:

What clues/signs can be gathered from the weather during the autumn months as to how the following winter may pan out. For example, sea surface temperature anomolies and weather patterns during the coming months......

Also how do these factors shape up in the context of this coming season?

If the SST's are very high, then airmasses flowing over are moderated and generally milder than usual, but also, this means their is more convection, and with colder air, monster snowfalls are possible from a warm sea.

I'd say weather patterns mean very little - but I do prefer for the Arctic/Greenland to keep it's cold and strengthen it throughout Autumn instead of giving us cooler blasts with it. If the Arctic continued to have high pressure and locked up all the cold air in, it would all amass together and we would get a mighty strong blast of arctic air if it then let it's floodgates open come Nov/Dec/Jan.

[CreweCold]

Isolated Frost, on 18 October 2011 - 17:12 , said:

If the SST's are very high, then airmasses flowing over are moderated and generally milder than usual, but also, this means their is more convection, and with colder air, monster snowfalls are possible from a warm sea.

I'd say weather patterns mean very little - but I do prefer for the Arctic/Greenland to keep it's cold and strengthen it throughout Autumn instead of giving us cooler blasts with it. If the Arctic continued to have high pressure and locked up all the cold air in, it would all amass together and we would get a mighty strong blast of arctic air if it then let it's floodgates open come Nov/Dec/Jan.

Yeah, I am personally of the opinion that a strong-ish PV around Greenland during late Oct-Nov is a help and not a hinderance as cold has a chance to 'bottle up'. Nov 2009 had a strongish PV in place during early to mid month and look what followed during DEC/JAN

[summer blizzard]

CreweCold, on 18 October 2011 - 17:18 , said:

Yeah, I am personally of the opinion that a strong-ish PV around Greenland during late Oct-Nov is a help and not a hinderance as cold has a chance to 'bottle up'. Nov 2009 had a strongish PV in place during early to mid month and look what followed during DEC/JAN

Statistics disagree as i have just illustrated in the winter thread.

Of the 9 Octobers which saw -AO conditions of -1 or deeper (weakest polar vortex), just 1 did not see a winter month with an AO value deeper than -1.

Edited by summer blizzard, 18 October 2011 - 17:43 .

[Snowmad79]

CreweCold, on 18 October 2011 - 17:18 , said:

Yeah, I am personally of the opinion that a strong-ish PV around Greenland during late Oct-Nov is a help and not a hinderance as cold has a chance to 'bottle up'. Nov 2009 had a strongish PV in place during early to mid month and look what followed during DEC/JAN

Maybe for the odd northerly toppler but not good if you want a pattern to build for sustained/ deep cold.

The stuff xmas nightmares are made of:



....



Prolonged mild Swesterlies a la 2007 . Lots of peeps used to discuss what a pain this pattern can be to shift if the PV sets up shop over or near Greenland and strengthens.

Edited by Snowmad79, 18 October 2011 - 17:52 .

[CreweCold]

Yes, during the winter months a strongish polar vortex is obviously a very bad sign for prolonged cold. However I'm not discussing actual winter mildness, strong PV etc, I'm more interested in the months prior to this. My point related to an issue IF pointed out in that constant seapage of cold uppers to mid latitudes during the autumn period may be detrimental to cold pool depth during the winter months.

SB thanks for taking the time, just had a little nosey at your findings and find it very interesting results wise.

[Snowmad79]

CreweCold, on 18 October 2011 - 17:54 , said:

Yes, during the winter months a strongish polar vortex is obviously a very bad sign for prolonged cold. However I'm not discussing actual winter mildness, strong PV etc, I'm more interested in the months prior to this. My point related to an issue IF pointed out in that constant seapage of cold uppers to mid latitudes during the autumn period may be detrimental to cold pool depth during the winter months.

SB thanks for taking the time, just had a little nosey at your findings and find it very interesting results wise.

Ha-ha that explains the point alot more, otherwise I would have had to have posted this one:

[Isolated Frost]

It's all about the jet:

Look at that low nr Newfoundland. In 3 days time-

It continues on it's track and pushes that high east quickly, sucking in very mild air to fall in the form of mild swlies in britain.
A couple more days on-

That traditional more north-south split. Average-mild, and very wet in the north, mild and sunny in the south. The low moves towards 60N and another one forms on a similar track.

Now lets look at November 21 2010. Similar lp positioning nr Newfoundland-

Come the 24th, this has stalled against a large block to the ne. It moves gradually south-

Shalakazaam! Here's the chart for the 28th-

Yes, that low is to the south of the page. Generally, as the jet gives lows to France/Spain instead of Scotland/Faroes, the lows stall, and becoming gradually cooler in Europe. They then move north towards Scandi against a tough block, and that gives very cold weather to Britain generally, in the form of northerlies and easterlies.

The jet stream in my opinion affects blocking in certain regions - so I believe a sly tracking jet is v important for our cold chances.

[johnholmes]

Can anyone point me to a link with actual average NAO and AO October values or charts for October over the past few decades please?

[Snowmad79]

johnholmes, on 18 October 2011 - 19:32 , said:

Can anyone point me to a link with actual average NAO and AO October values or charts for October over the past few decades please?

and the AO



Found these charts here: http://www.climate4y...eVariations.htm

Oh dear, not specifically Octobers sorry

Edited by Snowmad79, 18 October 2011 - 19:46 .

[johnholmes]

Snowmad79, on 18 October 2011 - 19:44 , said:

and the AO



Found these charts here: http://www.climate4y...eVariations.htm

Oh dear, not specifically Octobers sorry

never mind its the thought that counts-thanks-I doubt there is enough detail there for any close look at Octobers

[CreweCold]

johnholmes, on 18 October 2011 - 19:57 , said:

never mind its the thought that counts-thanks-I doubt there is enough detail there for any close look at Octobers

LOL, I don't think you meant that in a patronising way but I sure did read it like that and laughed out loud

I'm sure someone has the data. Mr Data would be a good option I think.

[Grimsby Snow Lover]

Wilth reference to post number 8. I personnaly found this very imformative and helpful in understanding what possible trends to look out for over the upcoming winter months. I must say those November 2010 charts look fantastic and anything similar this year would be a blessing. Thanks once again for a very imformative and easy to understand post

[johnholmes]

CreweCold, on 18 October 2011 - 19:59 , said:

LOL, I don't think you meant that in a patronising way but I sure did read it like that and laughed out loud

I'm sure someone has the data. Mr Data would be a good option I think.

no I certainly did not-as my school reports often said-'must try harder' in this case to make my thoughts clearer.

re my post about 500mb charts
I've had a look at the northern hemisphere 500mb chart sequence. The wave length of the two troughs in our area, that being the trough just west of us and the one over Russia towards the Caspian Sea? From T+120 to T+240 they only move slightly; the one in the west about 10 degrees east and the eastern one not at all other than extending south. Another feature to look at is the one that develops over the states by T+240. IF its correct it MAY have the effect of helping retrogression as it throws warm air up its eastern side towards Greenland?
Just a thought but I'd still rate the chance of it happening yet as no more than 50:50.

Edited by johnholmes, 18 October 2011 - 20:13 .

[Liam J]

We could have also said that the charts deep in FI some 4 months ago were the building blocks to a long hot summer? Which it certainly wasn't we ended up with the coolest since the mid 1990's.

People get shot down by other members for posting charts in deep FI, it's ironic that as soon as we start heading into winter suddenly charts in deep FI are now the building blocks for a cold winter. I'm sorry but model outputs in mid October have no bearing on what the weather will be doing in a month or two's time, IMO.

FI can, has and will show stunning charts that many of us will drool over in the coming months, and as usual it will cause a huge roller coaster of depression and euphoria at times - don't get sucked into this vicious cycle!! Go and follow the CFS model which will take you much further into winter 2011/12 with it's super deep Fantasy charts than the GFS, UKMO and ECM put together.

A good example has already been shown above, the October 2007 chart showing HP stetching from Russia over Scandinavia towards the UK then followed by charts with SW winds and LP dominating into December.

We all need to chill a little here, it's only mid October and for now winter will arrive as ever on the 1st of December, and winter weather will arrive when I see cross model agreement within T96 hours or less and not 300 hours+

We could have a cold winter, we could have an average winter or we could have a mild winter.

Edited by Liam J, 18 October 2011 - 20:29 .

[chionomaniac]

NAO monthly data here: http://www.esrl.noaa...lation/nao.data

AO data here: http://www.cdc.noaa....elation/ao.data

I'm not a statistician but I can't see any correlations between October NAO and winter NAO.

Edited by chionomaniac, 18 October 2011 - 20:34 .

[phil n.warks.]

John H,

You might find some usefull Stats here

http://processtrends.com/RClimate.htm

A mine of information on telecon histories and seaice cover etc.

[jean91]

Evening , thank you for post number 8 which is very informative and clear , one of the reason i come on neweathert forum.And regarding post number 15 also very good to put ourselves back on our feet.Have got preferences for winter but i will take what is served to us.

[bobbydog]

everyone can come up with forecasts, hopecasts etc, based on synoptics, lunar cycles, solar activity, sst's or any other factor you may care to mention. however the models are so wildly different from run to run in F.I. , which incidentally is only 15 days ahead, how can anyone hope to predict the winter when even the models cant show a trend. my opinion is, lets just wait and see...

[summer blizzard]

johnholmes, on 18 October 2011 - 19:32 , said:

Can anyone point me to a link with actual average NAO and AO October values or charts for October over the past few decades please?

The link has been posted above however in terms of the AO i analysed the data on page 6 of the winter thread.

An October or November with an AO value of -1 or greater will 85% of the time be followed by at least 1 winter month with a value in excess of -1. Given that the correlation between winter temperature anomoly and the AO values is pretty big, it stands to reason that a very negative AO Autumn value being followed by a very negative winter AO significantly increases the chances of a colder than average winter month.

I extended this back to August as August 2011 was the 3rd most negative on record and of 16 months with an AO value greater than -0.5, just 1 did not see a month with a winter AO value of -1 or greater.

In conclusion, at least 1 winter month this winter is looking good.