Winter 2012/13 - Chat

[Buriedundersnow]

This being an eg of lowering heights over the arctic.

I am still not coming off the fence but unless some sort of warming of the strat happens soon, we may have a close but no cigar, some people say that they wont be fully on board until a potent cold spell is on all models within T72, i would not go that far as i am prepared to listen to the experts at the 16 day range though, i will be happy when GP, chiono and the Met office are all singing from the same hym sheet, i suspect that the reason the Met are going with their half baked dry cold possibility is because their improved long range model is picking up strat signals that the EC32 is not. Maybe that equals a mid lattitude high.

could that high in the middle of the atlantic not progress north into greenland and then set up with the scandi high to block right across from greenland to scandi and give us an easterly

[feb1991blizzard]

The Stratosphere will be having little if any effect at the time scale of their 16-30 day outlook and it certainly is not part of the model at that range.

If the troposphere was to become unfavourable for blocking in the stated timescale ie (not saying it will of course) would i be right in saying that it would be eventually responding to what has been a reasonably unfavourable strat (certainly unfavourable upper strat) for the last few weeks then? Judging by what i have read, sustained potent cold is virtually impossible without a favourable lower strat and if the upper strat is cold for long enough then ultimately the lower strat will respond in time.

[feb1991blizzard]

could that high in the middle of the atlantic not progress north into greenland and then set up with the scandi high to block right across from greenland to scandi and give us an easterly

I suppose it could but without the upper strat warming up soon (see strat thread as now wave activity forcasts less than we need), the +ve zonal wind will filter down from the upper strat down to the lower strat and surely its only a matter of time before the vortex limpets itself to Greenland, any HP then likely to be mid latt at best and if there is any cold pooling, would end up going into france. just a thought, lets hope the models come up with the goos tonight though and throw all that out of the window!

[throwoff]

As I am in Kent France getting a cold blast could work, if it has the power just to blow over the thin channel and dump some on us!

[snowstorm445]

Forgive me if I'm wrong here, but aren't the NAO/AO 'forecasts' merely derivations of the model-run?

Yep. As you probably know already, it measures the difference in air pressure between Iceland and the Azores. If it is positive you can expect a large difference (i.e. deep PV and an Azores High), and a negative NAO is less of a difference (heights building to the North, lows further south etc.)

So if the NAO forecast shows a dip into negative, you can expect to see charts like the ones we are seeing at the moment appearing around the period that it goes negative.

[Barry12]

Looking forward to the Met's video forecast on Monday

Edited November 14, 2012 by Barry95

[Eskimo]

Looking forward to the Met's video forecast on Monday

Is that specifically for the end of the month?

[Barry12]

Is that specifically for the end of the month?

Yeah

[AWD]

Some nice charts from the CFS regarding the beginning of December too;

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=570&code=0&carte=1&mode=0&run=0

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=612&code=0&carte=1&mode=0&run=0

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=642&code=0&carte=1&mode=0&run=0

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=666&code=0&carte=1&mode=0&run=0

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=708&code=0&carte=1&mode=0&run=0

No extreme cold, but cold enough for snow in places at times. Then we move on to this;

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=852&code=0&carte=1&mode=0&run=0

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=894&code=0&carte=1&mode=0&run=0

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=930&code=0&carte=1&mode=0&run=0

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=978&code=0&carte=1&mode=0&run=0

Again, nothing too cold but cold enough for some snowfall. A run that I would happily take right now. All just eye candy for now off course.

[Bristawl Si]

Thing is though AWD ian fergie mentioned in a post yday that the meto never use these charts...ever.

I think he was saying in a polite way to just ignore them.

[AWD]

Thing is though AWD ian fergie mentioned in a post yday that the meto never use these charts...ever.

I think he was saying in a polite way to just ignore them.

I know, that's why I refrained from posting them in the MOD thread.

Just trying to find something to wet the appetite. :p

[Ben Sainsbury]

GFS

poss easterly forming or not??? hmm...

long way off tho

Edited November 14, 2012 by interestingweather

[mcweather]

Does anyone know what date GP will be releasing his winter forecast?

[virtualsphere]

I've been following the forecasts and analysis for the upcoming winter with interest and as usual there have been some excellent insights into the patterns to look out for from the experts.

What particularly interests me is when the more knowledgeable posters suggest a similar pattern, especially when they use different methods for forecasting. A while ago, GP suggested 1968-9 as a possible analogue for the conditions leading up to this winter. More recently Roger J Smith also mentioned 1968-9 in his forecast for the coming winter.

I'm not sure if the teleconnections still support the 1968-69 analogue, but Roger highlights a possible switch from a mild January to a cold February, which is quite an unusual pattern - and one which occurred in 1969. With this in mind, I thought it would be worth taking a closer look at that winter. Apologies if these have been posted before as I know there has been some discussion about 1968-9.

These are pressure anomaly charts for the winter:

Worth bearing in mind these are just average anomalies over each of the months, and not necessarily where the low and high pressure is actually situated. In all three winter months, higher than normal pressure exists over the north with lower

pressure situated to the south of the UK and Europe - a pattern those looking for cold weather will want to see this year.

Now here are the surface air temperature anomalies for each month:

In December 1968, colder temperature anomalies just scrape the south east of England, but move away from the UK during January 1969 despite the significant northern blocking. Looking at the pressure anomaly chart for January 1969, you can see how the high pressure is too far east, allowing low pressure to set up too close to the UK and bring a southerly flow. This brought milder temperatures - look at the upper air temperature on this chart despite the blocking to the east:

The low pressure manages to push the block further east by the middle of the month. A familiar story perhaps? The 17th January 1969 did bring thunderstorms and 12mm hail to Berkshire according to the Met office:

In February, though, look how the blocking to the north west extends further south into the Atlantic, shifting the low pressure just slightly south east of January's pattern into a more favourable position (a more "east based" -NAO), which allowed set-ups like this to develop:

Monthly weather summaries:

Feb 1969 http://www.metoffice...d/1/Feb1969.pdf

Jan 1969: http://www.metoffice...c/8/Jan1969.pdf

Courtesy of Met Office: http://www.metoffice...er-report-1960s

Reading the model and stratosphere threads, it certainly seems there is a battle this year between some promising teleconnections against a (currently) colder stratosphere. I don't know enough to be able to comment in detail so will leave it to the experts, but if we are looking at a similar pattern to 1968-9, it is certainly worth waiting a while before writing off the winter!

Edited November 14, 2012 by virtualsphere

[johnholmes]

thanks for that vs, a very interesting post.

[Alan Medlock Valley]

Oh dear if a potent "cold" spell doesn't come off as thought in a couple of weeks then some of the experts in here that just a few days ago seemed confident of it happening will end up with a very sore head through pulling hairs out by December. But if it does happen then I will to you all for sticking to your guns. Let's face it though as of tonight the chances of a November/December 2010 style freeze are low, there really can be no illusions of that. Things do change though but we do need consistency and soon.

[I remember Atlantic 252]

Oh dear if a potent "cold" spell doesn't come off as thought in a couple of weeks then some of the experts in here that just a few days ago seemed confident of it happening will end up with a very sore head through pulling hairs out by December. But if it does happen then I will to you all for sticking to your guns. Let's face it though as of tonight the chances of a November/December 2010 style freeze are low, there really can be no illusions of that. Things do change though but we do need consistency and soon.

November a write off (autumn anyway) but Dec, still a blocked trend for at least a cold dry start to Dec, got to be the likely thing

[Alan Medlock Valley]

Yes I should of said November/Early December 2010, I'm certainly not writing off the whole of December.

[SnowObsessor90]

Just I was the about to completely throw in the towel the 18z throws us another little tease in deep FI. Oh why oh why do the models keep doing this to us lol

[feb1991blizzard]

This might have just come in time to stop the negativity spread in here, i actually had this chart as one of my 2 selects as the run came out (the other being H500 of course), purely by chance as i had seen the last chart posted by chiono in the strat thread, i thought it was definately positive as the vortex was splitting, i had to check though as although the blues got more pale, the yellows and greens shrunk over the other side of the hemisphere, so to make sure, i went straight into the strat thread, there was chiono's post about it, shining brightly for all to see!!!

http://forum.netweather.tv/topic/74587-stratosphere-temperature-watch-20122013/page__st__640#entry2404259

[Snowy Easterlies]

Just I was the about to completely throw in the towel the 18z throws us another little tease in deep FI. Oh why oh why do the models keep doing this to us lol

throw in the towel? im a pessimist but giving up chasing cold in november is a bit silly

Edited November 15, 2012 by Snowy Easterlies

[SnowObsessor90]

throw in the towel? im a pessimist but giving up chasing cold in november is a bit silly

I meant for any potential early cold spell in late November, early December etc, that's not say that I'd be necessarily writing of the next few months although ideally we could really with do more of what 18z is showing in it's latter frames other the next days and beyond just to make things that little bit easier

Edited November 15, 2012 by Anonymous21

[Barry12]

Whens the NW official winter forecast come out?

[Coast]

Whens the NW official winter forecast come out?

Very soon!

http://forum.netweather.tv/topic/74915-early-winter-thoughts/#entry2398863

[Barry12]

Very soon!

http://forum.netweather.tv/topic/74915-early-winter-thoughts/#entry2398863

So no official release date?