Model Output Discussion - 5th December - 11th December

[Bristawl Si]

I must admit i'm a little surprised at some of the 'frustration' on here in recent days.

The North/South split as we're seeing at the mo, with the North being affected by PM incursions from the North West is pretty normal for early Winter in the UK.

Despite the last couple of winters, generally here in the South we don't see much cold/snow action until the New Year and into Jan/Feb - and even then it tends to be a few days cold snaps rather than prolonged spells -- certainly that's true for Bristol and the surrounding areas anyway, in my lifetime, bar the odd winter (2010, 2009, 1981)

Having read GP's winter forecast the other week and reading his posts of late on here (plus Chino's posts), on a national scale any widescale change to a more sustained cold spell (and maybe widespread snow) is still favoured for later in the Winter period.

The model output over the last few days still seem to favour a north/south split in terms of temps and whether it be dry or wetter - the Euro high still seems to be having a major influence on our weather for the next couple of weeks to some degree - favourite in my book is to see average temps and dry in the south, with the north more unsettled and colder.

A winter of two halves maybe? i.e. North and South

Edited December 5, 2011 by Bristle boy

[weathergeek]

Please excuse my naiveness as I know little about the weather but have been reading this forum for a few mths now and just a bit confused.... How long would models need to be saying the same thing before its regarded a trend and therefore more of a reality?

I would dearly love cold/snow (Epsom so litttle chance!) but the models were saying cold for a few days and now after just one day of "not so cold" everyone now thinks that is definitely what will happen/get all depressed/sad emoticons etc (lol) and yet the models may say different again tomorrow/next day then everyone's excited again??!! Been so wound up and disappointed so many times from this thread - I tell myself I'm just gonna check in once a week but I'm annoyingly addicted a bit now, lol!

Please explain somebody and remember I'm a complete novice so please don't shoot me down, nice explanations only please!

H x

[conor123]

Early days but a potential serious storm for Scotland Thursday into Friday with blizzards and gale force winds possible, Northern England & Northern Ireland possibly in the firing line for Gales to and then wintry showers for many Friday.

The trend a bit better on the 18z for a slider low, still not quite the right ingredients but the trend is there which is something.

[alijoe]

Please excuse my naiveness as I know little about the weather but have been reading this forum for a few mths now and just a bit confused.... How long would models need to be saying the same thing before its regarded a trend and therefore more of a reality?

I would dearly love cold/snow (Epsom so litttle chance!) but the models were saying cold for a few days and now after just one day of "not so cold" everyone now thinks that is definitely what will happen/get all depressed/sad emoticons etc (lol) and yet the models may say different again tomorrow/next day then everyone's excited again??!! Been so wound up and disappointed so many times from this thread - I tell myself I'm just gonna check in once a week but I'm annoyingly addicted a bit now, lol!

Please explain somebody and remember I'm a complete novice so please don't shoot me down, nice explanations only please!

H x

Feel EXACTLY the same. so confused I am going to deffinately only check in once a week..... or else, if I cannot sustain this, may have to join weatherannonomous. Confused.com is me.

[Grimsby Snow Lover]

Please excuse my naiveness as I know little about the weather but have been reading this forum for a few mths now and just a bit confused.... How long would models need to be saying the same thing before its regarded a trend and therefore more of a reality?

I would dearly love cold/snow (Epsom so litttle chance!) but the models were saying cold for a few days and now after just one day of "not so cold" everyone now thinks that is definitely what will happen/get all depressed/sad emoticons etc (lol) and yet the models may say different again tomorrow/next day then everyone's excited again??!! Been so wound up and disappointed so many times from this thread - I tell myself I'm just gonna check in once a week but I'm annoyingly addicted a bit now, lol!

Please explain somebody and remember I'm a complete novice so please don't shoot me down, nice explanations only please!

H x

Hi Weather geek,I do see you point so I will try and explain a few things for you. Firstly charts at the minute are generally reliable up to around 4 days so anything beyond that I wouldn't worry about at the minute as the weather is very disturbed and likely to change so what.. Secondly use the GFES charts as these show where about the operational run (the one we see) fits when compaired to the other runs. Sometimes these show that the operational run was an outlier (on its own). Generally for a new trend to occur we need to see the UMKO, ECM and GFS singing off the same hymn sheet before anything concrete can be agreed. At the minute they are all showing unsettled weather coming from the west/north west. Beyond Saturday who know.

Edited December 5, 2011 by Grimsby Snow Lover

[Matty M]

well the 18z isn't fantastic but i do think there is some chance of a slider.

I wouldnt write off a chance of the shortwave sliding across.

[Icequeen]

Feel EXACTLY the same. so confused I am going to deffinately only check in once a week..... or else, if I cannot sustain this, may

have to join weatherannonomous.

Confused.com is me.

Me to, love this forum too much at the moment. Keep up the good work, I shall continue to admire in the shadows.

[Tom Montalbano]

Just a quick update on the feature expected to hit the N.Isles and possibly extreme N.E parts of the mainland of Scotland tomorrow morning.

http://www.sat24.com/include/images/trans.png

Its just reaching the Faroe Islands now.

Regards,

Tom

[lorenzo]

Can someone please write

1 A definition of the term short wave

2 A definition of the term slider

Thanks.

[weathergeek]

alijoe - I feel your pain and will see u at W.A, lol!

GSL - thank you for kindly explaining that....so now all models are kind of saying not cold by Fri that's pretty much a given - as in there is less chance of checking this over breakie and seeing a whole new set of promises, lol?!

Icequeen - I've tried to stay off but with a smartphone in my hand the addiction is too strong and I am too weak! I really have become my username, lol!

H x

[Grimsby Snow Lover]

alijoe - I feel your pain and will see u at W.A, lol!

GSL - thank you for kindly explaining that....so now all models are kind of saying not cold by Fri that's pretty much a given - as in there is less chance of checking this over breakie and seeing a whole new set of promises, lol?!

Icequeen - I've tried to stay off but with a smartphone in my hand the addiction is too strong and I am too weak! I really have become my username, lol!

H x

Your welcome WG, just wait until the real cold and snow hits and begins appearing in the models it gets mega exciting on here, plus the server often crashes.

Well, more suprises from the pub runs FI. It shows the PV displaced and heading off towards Scandinavia and blocking of sorts building over Greenland,all be it weak.

http://hw.nwstatic.co.uk/gfsimages/gfs.20111205/18/228/h500slp.png

[weathergeek]

Omg with my addiction, a crashing server could just about tip me over the edge, lol!

I am sure we will def get some snow down here at some point, I feel it in my bones, even if its just a big one off event it will have to do - enough to use my new snow boots and take the kids out on the sledge!

H x

[nick sussex]

Yuk!!!

Flat upstream pattern, limpet PV, you're not going to get PM incursions with that, average/cooler zonality often turns into just mild mush!

At this point I'd take a Euro high with surface cold!

This is the problem unless you get some amplification upstream then theres only one way to go with a limpet PV, someone order an emergency SSW!

[mountain shadow]

Can someone please write

1 A definition of the term short wave

2 A definition of the term slider

Thanks.

Look up long wave trough on Google, a short wave is a trough or area of low pressure wish forms off the long wave.

A slider low is a low pressure system which moves down from Greenland into northern France as opposed to running north of Scotland as usual. A slider can occasionally encourage pressure rises over Scandanavia bringing easterlies to the UK.

[Buzz]

Can someone please write

1 A definition of the term short wave

2 A definition of the term slider

Thanks.

In addition to that:

3 A definition of the term 'Phasing'

[mountain shadow]

In addition to that:

3 A definition of the term 'Phasing'

Replace the word phasing with interacting. I'ts where two low pressure systems either interact or phase with one another or not as the case may be.

[lorenzo]

Look up long wave trough on Google, a short wave is a trough or area of low pressure wish forms off the long wave.

A slider low is a low pressure system which moves down from Greenland into northern France as opposed to running north of Scotland as usual. A slider can occasionally encourage pressure rises over Scandanavia bringing easterlies to the UK.

Thank you MS i had a fair idea via Haby hints et al , but thought that a more eloquent explanations would contribute to folk reading this thread and looking at models, your description much more concise than mine would have been !

[jonnybradley]

This is the problem unless you get some amplification upstream then theres only one way to go with a limpet PV, someone order an emergency SSW!

Whats the score with that upstream Nick? Not seen you post anything on that for a while so guessing there is nothing to report in terms of potential developments?

Jon

ps Had a look at CFS earlier. One of its runs t+700 and something it put a high pressure in to the vp (1050mb?), pushing in from the Bering Straits right into the North pole. lol really put the cat amongst the pigeons, if only.... shame I didn't save it, made my day

[bluearmy]

NOAA cpc not impressed with the terrible run to run inconsistencies from GFS and ECM. Better to stick with the ens although we know that this may well not be the answer. I wonder if stewarts remarks last evening re the nwp struggling with non Nina placing of troughs/ridges is showing itself ?

I am still intrigued somewhat by the models wanting to place small areas of slightly higher heights in the arctic. My experience of these is that if they do indeed verify, they seldom fail to make an impact. As ed posted on the strat thread, the strat p/v centre is likely to relocate to the pacific side of a generally stretched p/v. I just wonder if that will allow some subtle height rises to our north which could push the zonal flow a bit further south ???

[phil nw.]

Yuk!!!

Flat upstream pattern, limpet PV, you're not going to get PM incursions with that, average/cooler zonality often turns into just mild mush!

At this point I'd take a Euro high with surface cold!

This is the problem unless you get some amplification upstream then theres only one way to go with a limpet PV, someone order an emergency SSW!

Lol--at least it`s not double figures max`s every day Nick.

The Jet is modelled to be south enough for at least average conditions going forward .

Actually scotland looks quite cold most days with further snow at times.

As ever for us in the South it` is a less cold scenario but it could be a lot worse with such Low Hts over the Pole.

[SMU]

Evening All-

I know I keep on but Im convinced the ECM & the GFS are wrong with ramming the atlantic down our throats at 168-

Im expecting more trough Disruption over Southern Greenland - so we get a long trough extension all the way from South Greenland all the way out to France...

The Control is Interesting-

Heres a thought- we have had endless after endless ensembles that have all shown repetative zonal weather crashing into Europe- & yet to date we havent got there with one low & SW winds..

Looking forward to a possible change in the 00z's!

S

Edited December 5, 2011 by Steve Murr

[Ruzzi]

The north of Scotland could get a real pasting on Friday looking at the charts tonight!!!

[Richard Lake]

GFS 18z is a big upgrade in the next 4-5 days. Since Friday and up until the 12z of today, Wednesday was progged to be quite mild - the 18z is showing still mild, but the cold front is holding out until daylight Thursday morning and lasting til 3pm that very same day. Thursday night and into Friday morning is showing a fairly average Low piling into the North Sea with winds pulling into a near-straight Northerly. By Saturday morning mild air is beginning to move from the South up as far as the Midlands under a slack airflow. I suspect that the deep cold on Thursday/Friday that is spread across most of the country will mix out most of this mild air attempting to flood North. Hard to say what will happen next, but I rather suspect that winds will continue on a Westerly through to Saturday alternating between WNW and NW into Sunday potentially giving us yet another chance at a short-lived cold shot going into next week.

@ruzzi: If GFS keeps showing what it currently does I'd expect anywhere north of Leeds to see high winds and potential for snowfall increase significantly. However I keep thinking 'wishbone effect' in the back of my mind.

Edited December 5, 2011 by djrikki

[nick sussex]

Lol--at least it`s not double figures max`s every day Nick.

The Jet is modelled to be south enough for at least average conditions going forward .

Actually scotland looks quite cold most days with further snow at times.

As ever for us in the South it` is a less cold scenario but it could be a lot worse with such Low Hts over the Pole.

The crumb of comfort is basically what BA just posted with the PV perhaps edging west eventually, maybe we'll get the trough lifting out, Azores ridge heading north, ridge to the east extending west combo, there sorted!

Easterly for Xmas! :smiliz19:

Edited December 5, 2011 by nick sussex

[Ruzzi]

@ruzzi: If GFS keeps showing what it currently does I'd expect anywhere north of Leeds to see high winds and potential for snowfall increase significantly. However I keep thinking 'wishbone effect' in the back of my mind.

Yup, I've been thinking the same thing away from the extreme north of Scotland. It wouldn't be good news for me considering I'm pretty much slap bang in the middle between Glasgow and Edinburgh, however I have half a foot of lying snow just now so I guess I shouldn't get too greedy. My location does tend to do very well from northerlies if there is an organised band of snow accompanying it, but that does look unlikely imo.