Winter 2012 / 2013 Part 2

[feb1991blizzard]

And what about Bingley, what elevation is that? cant be much more than a thou, or 1.2 surely

[feb1991blizzard]

Haha it's nice to see on a chart anyways, what joy the little snow symbol can bring even if it has a raindrop next to it

Not sure if i got it right, i typed in bingley to see forecast and nothing wintry came up, then typed in my postcode and the sleet symbol came up, i dont know whether its right or not, i went to met office observations but they are unavailable, i will have a look at last 24 hours tommorow.

[johnholmes]

I'm afraid I have nothing of note to add other than to thank those contributing to a sensible constructive discussion, differences arising but absolutely no name calling going on.

A model for the model thread perhaps?

Comments in this and the other 'winter' threads are quite fascinating and who knows what may come from them.

Before I retired 90% of what is being discussed on here was pretty much unknown by most practising professional forecasters which shows just how many advances in knowledge the weather community have made in the last 15-20 years.

[cheeky_monkey]

I'm afraid I have nothing of note to add other than to thank those contributing to a sensible constructive discussion, differences arising but absolutely no name calling going on.

A model for the model thread perhaps?

Comments in this and the other 'winter' threads are quite fascinating and who knows what may come from them.

Before I retired 90% of what is being discussed on here was pretty much unknown by most practising professional forecasters which shows just how many advances in knowledge the weather community have made in the last 15-20 years.

that's one reason i haven't been in the model thread for over 2 years

[SMU]

I just reanalized all 10 years on that image from the worst -AO years & its not a conclusive correlator- there are 2 years when the DEC AO is postive, 3 that are neutral & 5 that are negative-

We would need to list these years & see how the other teleconnectors were sitting-

I wonder what the November stratosphere was in those negative years....

S

Edited October 3, 2012 by Steve Murr

[Cheese Rice]

And what about Bingley, what elevation is that? cant be much more than a thou, or 1.2 surely

Bingley is near me. It's around 160-180m above sea level.

As Leeds Airport reported only rain with a temp of 6.c I'm more than inclined to favor it was rain falling.

[ZONE 51]

First of all thanks to all the great input in this and the other threads, it's been very interesting. Maybe one day the 'code' might be cracked, it is very complex and with new factors coming into play like record low Arctic sea ice it will only get more difficult, the ASI situation is bound to play a major part in world weather patterns, it's just how.

I've been looking at the possible connection with non-imported thunderstorms/plumes and increased snowfall, particulary across the SE UK where it has been more noticed as we were used to lack of snowfall. But why is this? it seems that our weather patterns have shifted south maybe southeast, if this does continue then we can expect cooler summers, less heatwaves, more blocked patterns.

Another thing that could be happening is less southwesterly's and increased northwesterly's?

Whatever is going on since 2009(maybe 2007) it is a massive climate pattern shift.

ESS

Edited October 3, 2012 by ElectricSnowStorm

[ZONE 51]

http://www.ncdc.noaa...eleconnections/

If you would like to know what things mean like the AO/PDO..that are said frequently on the forum then check out the above link.

Edited October 3, 2012 by ElectricSnowStorm

[Formula_1_Fan]

I think the change in weather patterns since 2007 is probably because I bought a covertible and moved to a small village on the edge of the North Yorks Moors. Roof up most of all summers since and pretty impossible to get anywhere in some of the recent winters. Just want to say another thank you for all the great posts, really interesting reading!

[Snowy Easterlies]

i don't like the GFS charts in FI, its shows the azores high ridging in, and has been doing for some runs now

i may be totally wrong but i hope some sort of euro high don't set up shop for ages now, we can all say its only october, but remember last year, we said its only october, november when it was horribly mild, but we had to wait till February for anything cold and snowy, i just hope my amateurish predictions are wrong, and hope there isn't a similar repeat to last winter

I cannot stand boring, mild, dry settled spells in autumn, i hope we see some gales, lots of rain and its chilly too, so yes cold zonailty would be fine, then bring on the raging easterlies in winter

Edited October 3, 2012 by Snowy Easterlies

[Met4Cast]

i don't like the GFS charts in FI, its shows the azores high ridging in, and has been doing for some runs now

I wouldn't worry too much just yet, the models diverge quite a lot, even within the GFS Ensemble suite

There's a signal for heights to begin to rise across the Arctic, this tends to limit chances of Azores High, I think a mid-Atlantic ridge would be more likely at the moment

[Suburban Streamer]

What could & should a Winter forecast offer-

Hi Steve are u going to issue a winter forecast this year? Last year you put in your signature that u had "very high expectations of winter". It would be great to see a winter forecast from you this year....

Edited October 4, 2012 by Suburban Streamer

[shedhead]

that's one reason i haven't been in the model thread for over 2 years

And why I won't be posting in there this Winter...despite posting in there throughout Spring/Summer with no issues.

[gottolovethisweather]

Here's my broad brush feel about things as we stand, over in the Northern Hemisphere thread.

http://forum.netweather.tv/topic/74146-snow-and-ice-in-the-northern-hemisphere-201213/page__st__440#entry2377495

[Glacier Point]

I just reanalized all 10 years on that image from the worst -AO years & its not a conclusive correlator- there are 2 years when the DEC AO is postive, 3 that are neutral & 5 that are negative-

We would need to list these years & see how the other teleconnectors were sitting-

I wonder what the November stratosphere was in those negative years....

S

I get two years (1965 and 1959) where these are neutral values for December. The remainder all deeply negative with an average value for December AO of -1.4

http://www.cpc.ncep....ent.ascii.table

There's quite a lot of published research out there suggesting a periodicity of 90 days between the start of these events triggered by rapid growth in Eurasian snowcover. The theory being rapid growth in snowcover leads to linear disruption of the zonal flow with subsequent dumping of westerly winds across 40N leading to torques setting up eddy fluxes poleward which in turn generate ascending columns of air (anticyclones) which generate Rossby wave trains poleward (Wave 1 and 2) which deccelerate the polar night jet and eventually culminate in warming events. There might be a secondary surface flux - eddy shift associated with the North Atlantic in November and December (meridional flux).

Thats a long chain which takes some considerable time and takes place across the northern hemisphere with circumhemispheric ridge and troughs (remember 2009's four wave pattern ?) to achieve but the emphasis is placed on the whole thing starting with October gain in snowcover which must mean the patterns leading to this should be evident within reanalysis for October. That's why I'm very keen on monitoring surface zonal flux over Siberia during over the next few weeks.

Interestingly, your question about stratospheric profile in November preceeding the top 10 most negative AO winters....guess where the warm anomaly is...

Note also the coolish stratosphere over the tropics and in the southern hemisphere. That implies we need the polar vortex over Antartica to be going strong well into their spring.

Current AAO profile:

http://www.cpc.ncep....gt.aao.cdas.gif

maybe not as ideal as would like there with a +ve height anomaly in the stratosphere which might downwell.

Edited October 4, 2012 by Glacier Point

[Methuselah]

I'm very interesting in seeing what happens, in the way of high-latitude snow cover, when the first blasts of polar air blow over the relatively warm Arctic Ocean...

[latitude]

And why I won't be posting in there this Winter...despite posting in there throughout Spring/Summer with no issues.

Probably due to you getting slated for mild rampings when snow was falling!

[Met4Cast]

06z GFS FI throws up an interesting scenario, keeping with the trend..

-5c Isotherm over much of the country! FI of course, fun to see nonetheless

[latitude]

06z GFS FI throws up an interesting scenario, keeping with the trend..

-5c Isotherm over much of the country! FI of course, fun to see nonetheless

I would call it more a fleating glance for Scotland before moving away...but encouraging. FI seems to be showing 'colder' scenarios a lot recently. Yes..its FI, but trends are the way forward if you ask me.

[snowy weather]

What does the -5 isotherm mean

[SMU]

Stuart just quickly as im at wk- I re-analised using the Composite anomaly charts & just reviewed the area around NW europe & greenland-

I know thats slightly against the AO Background you presented- however If we are going to use the october flux then I would think the way forward is

Step 1- October trending in flux locations- how that teleconnects to Winter AO 'READING-

Step 2- Hardest bit that I dont think you did- of the sample data what is the correlation to the NAO, as in the 10 years you gave me 2 of teh years ( i cant remember) had a positive December NAO even if the background DATA was-AO-

Again quickly jotting down my thoughts- we should use the October surface flux in the preliminary winter thoughts that you may offer in October

Unless you have found the link from October flux to NAO pattern then the AO itself only supports a hemisperic loading pattern, not a pattern primed for cold for the UK- & therefor would be useless for NW europe- only useful for 50-70N anomalies-

Especially when you add in that on average you only get 2 standing waves in an AO- not a full 4.

Steve

Edited October 4, 2012 by Steve Murr

[AWD]

What does the -5 isotherm mean

It brings a possibility of snow, but only if other factors also play ball.

Edited October 4, 2012 by AWD

[bluearmy]

Anyone spot that for the first time this season (as far as i recall), the london meteociel ens are now illustrating a risk of snowfall. the 00z run had 2 of the twenty runs delivering whilst the 06z has one in twenty on several occasions. before you get excited, this will be a common occurance over the next six months but until you see > 50% figures within seven days, dont get interested.

[Radiating Dendrite]

It brings a possibility of snow, but only if other factors also play ball.

The -5 850 isotherm is basically a measure of the temperature at the 850hpa level (around 1500m ASL).

It can lead to sea level snowfall, but given the month, I would expect nothing more than a little snow in Scotland on the higher ground.

[latitude]

What does the -5 isotherm mean

air temp at 18000 feet?