Model output discussion - here comes the beast!

[Mark Neal.]

2 minutes ago, Steve Murr said:

so we are going into How mcn depth mode now-

First GFS run @60cm & that excludes convection really-

If you are interested in what the GFS 18z  would equate to in your backyard. http://www.xcweather.co.uk/forecast/ XC uses the GFS model for its text forecasts.

[Stuie]

11 minutes ago, Mark N said:

This would keep everyone happy! 

  

The poor folks in Oban, get lashed with rain all year round and miss out on the white stuff. The irony....

[chionomaniac]

I have to say when I suggested at the start of the month that the Strat was setting us up for a great cold spell, I thought that the potential was good but never envisaged this good. Again enjoy!

[Stuie]

2 minutes ago, chionomaniac said:

I have to say when I suggested at the start of the month that the Strat was setting us up for a great cold spell, I thought that the potential was good but never envisaged this good. Again enjoy!

Pleased for you mate, your hobby/dedication has really paid you back.

Edit: Not quite yet but you know what I mean.

Edited February 22, 2018 by Stuie W

[Nick F]

8 minutes ago, khodds said:

I know that Low has been showing for a couple of days now, but what’s the betting it will go south? It seems to quite often correct that way if I’m remembering rightly. Or are The Synoptics different this time?

Normally lows moving in across France and modelled this far out to affect southern Britain normally end up further south and often the precip missing the UK completely. 12 EC miseses the UK later next week with lows moving much further south across Spain and southern half of France, so would have low confidence in 18z GFS low coming up from France later in the week verifying.

Edited February 22, 2018 by Nick F

[supernova]

17 minutes ago, johnholmes said:

flactuate!!!

Are you predicting a lot if wind then?

Flactuate (VERB): Pron: Flack-Tu-Ate. Def: To agitate weather forum members beyond the point of excitement. In extreme circumstances flactuation can lead to site-host failure, off-topic posts, banning of over-zealous contributors, and individual delusion leading to "winter is over" "where's the breakdown" and "not as good as nineteen something" posts. Also (ADVERB), flactuate, spouting of hot air when a model is summarised prematurely. GFS too far north! Breakdown imminent! When said model goes on to produce snowiest evolution yet.

I requote @SnowBallz Next week is mega.

 

[khodds]

1 minute ago, Nick F said:

Normally lows moving in across France and modelled this far out to affect southern Britain normally end up further south and often the precip missing the UK completely. 12 EC miseses the UK later next week with lows moving much further south across Spain and southern half of France, so would have low confidence in 18z GFS low coming up from France later in the week verifying.

Thanks Nick. Interesting that it’s shown on most models. Time will tell! 

[Eskimo]

1 minute ago, Nick F said:

Normally lows moving in across France and modelled this far out to affect southern Britain normally end up further south and often the precip missing the UK completely. 12 EC miseses the UK later next week with lows moving much further south across Spain and southern half of France, so would have low confidence in 18z GFS low coming up from France later in the week verifying.

I notice, however, that the MetOffice have been talking about the possibility of it affecting the UK - obviously with some caution. Must be at least some confidence in the models for them to bring it up so early? *clutches at straws*

[CameronWS]

17 minutes ago, Karl83 said:

Wow! Nationwide snow event! Don't know about you guys but I'm ready for my snow burial!

Would that head north into Scotland?

[cold snap]

So GFS 18z wants to put us into a truly severe cold period with many feet of snow for some.

This is not a over hype .this is what it's shows.

Craziest cold run I've ever seen but most probably a outlier.

[Man With Beard]

ECM clusters - awesome again. Will try to post later. Basically no breakdown from the south, worst case scenario NWlies by D10 but they aren't mild

[smith25]

1 minute ago, cold snap said:

So GFS 18z wants to put us into a truly severe cold period with many feet of snow for some.

This is not a over hype .this is what it's shows.

Craziest cold run I've ever seen but most probably a outlier.

Yes and hopefully a mild outlier! 

[BLAST FROM THE PAST]

7 minutes ago, pages said:

o and look here comes the Artic high where is that heading back to Scandie lol we are locked in

Quel supris?  Spring is for late April,and May.......?

 

BFTP

[pages]

5 minutes ago, chionomaniac said:

I have to say when I suggested at the start of the month that the Strat was setting us up for a great cold spell, I thought that the potential was good but never envisaged this good. Again enjoy!

Talking of the Strat warming do you think the models may still be under doing high lat blocking in week 2. surely with the 2nd warming just finished.  we should see the main trop response roughly 2 weeks latter. 18z is 1st run we have seen with heights over artic in week 2 albeit very weak ,do you think we may see stronger heights transfer back towards scandie through the Artic in the 2-3 week period? 

[ItIsGee]

3 hours ago, Paul said:

We have them on the viewers (GFS and Netwx Models) in NW Extra if you still have a sub  

Looking a tad chilly on them

Thanks! I’m clearly not looking properly! I have a sub!!

[kold weather]

Well the 18z finally moves the cold away at 348hrs, probably a big snow event first though for most. Could be some big flooding if the milder air did come in quickly enough at the surface.

Also everything should just note that neat little upper high poking down from the Arctic which keeps the cold air flowing in when combined with the upper low in the atlantic.

I think its finally time...cold and snowy easterly...NAILED ON!!!!!

[ICE COLD]

3 minutes ago, sorepaw1 said:

If the models are showing all this predicted snow why aren't the BBC weather forecasts telling the general public this.

Hope this is a valid post.

Look on there week ahead forecast on the website they mention this low coming up towards the end of the week . But unsure of the track . ?

[chionomaniac]

2 minutes ago, pages said:

Talking of the Strat warming do you think the models may still be under doing high lat blocking in week 2. surely with the 2nd warming just finished.  we should see the main trop response roughly 2 weeks latter. 18z is 1st run we have seen with heights over artic in week 2 albeit very weak ,do you think we may see stronger heights transfer back towards scandie through the Artic in the 2-3 week period? 

Yes and yes.

I think that the cold will last until the second round of negative strat anomalies push to the surface and reinforce blocking. But less certain than I have been about this first round. If we keep the cold air against the initial push of returning westerlies then round two will be less pronounced but still better than most wintry spells seen over the last few years. There will be enough time to push the snow to the side before it comes again lol.

[weirpig]

The feature around 120 hrs is on the control also  good consistency there. 

[Mike Poole]

ECM mean at T138, words fail me

Edited February 22, 2018 by Mike Poole
Sorry that's GEFS mean, my bad!

[danm]

21 minutes ago, Catacol said:

Significant chance of serious disruption now in place. I wonder how long the media forecasts will stick to "very cold - but snow amounts and location uncertain." They are correct in the strict accuracy of the statement, but are being slightly coy in withholding the truth of the situation. Convective shower activity is going to be extensive such will be the instability over the North Sea from Monday onwards, and small features are certain to crop up. 

And then we have cross model agreement for significant snowfall next week on Thursday.

ECM = heavy snow for the south

GFS = heavy snow for the south

GEM = heavy snow for the south (slight easterly bias)

UKMO looks as though the next frame for Thursday would be heavy snow for the south

ICO = heavy snow for the south (slight westerly bias)

EPS would agree

as would GEFS

As this is still a week away there is obviously room for movement, but in reality this is remarkable consistency and fits hand in glove with impact of SSW and ongoing reversal, though by Thursday at 10hpa this will have changed and we will slowly recover our westerly shape in the strat. Not that this will impact significantly on the troposphere within the next 2 weeks...

I think our roadmap is becoming clear. Significant shower activity on the near horizon and a full on SW to NE event mid to late week. Warmer air from a moderately well defined system at around 975mb bumping in to the very severe cold in place is going to set off the mother of all blizzards for somewhere.... probably France now I've posted this!!

 

 

Removing the images to save space.

Excellent post - there is definitely a signal from all the models today towards a potentially significant snow event in the southern half of the country next Thursday. The good thing for us at the moment is due to the complete reversal of the zonal wind, we are at far less of a risk of a system such as this coming in from the south and introducing mild air or a breakdown as we often see in more traditional UK cold spells. So IF we get a direct hit in this scenario, it’s likely to be all snow due to the entrenched cold in place and the fact that we are very unlikely to be seeing a push from the Atlantic this time next week.

To be fair to the BBC here, on this evenings week ahead forecast, they did point out this exact scenario with the potential for very heavy snow moving into the south next Thursday, but that the track and location would be up for debate as you’d expect. Louise Lear even showed graphics for next Thursday with heavy snow across the south. 

[high ground birmingham]

18 minutes ago, Nick F said:

Normally lows moving in across France and modelled this far out to affect southern Britain normally end up further south and often the precip missing the UK completely. 12 EC miseses the UK later next week with lows moving much further south across Spain and southern half of France, so would have low confidence in 18z GFS low coming up from France later in the week verifying.

Yes I agree with this assessment. Most likely for it to stay south.

The time that I recall such a low moving up north through the UK was February 2005 but that was quite a disappointing event for many with constant falling snow but no settling

[ScottishSnowStorm]

Been watching the models for 8 years and seen a lot of great charts but to see all sorts of ridiculous charts this past week from easterly winds stretching from alaska to florida to complete reverse zonality it has to be said this chart tonight is just an utter thing of beauty and would be awsome to see something like this verify in my lifetime 

[Robbie Garrett]

Just now, high ground birmingham said:

Yes I agree with this assessment. Most likely for it to stay south.

The time that I recall such a low moving up north through the UK was February 2005 but that was quite a disappointing event for many with constant falling snow but no settling

I am trying to re-collect a similar situation in April 2012. The low that came up from France and dumped 48 hours rainfall on the South.  I think that was it?

[NickR]

1 minute ago, blizzard81 said:

I bet they didn't mention the snow threat for the north for next Tuesday? 

The "south" event also seems to hit large parts of the north. Not sure why, for example, the 18z was posted as showing heavy snow in the south when it's all of England and Wales before moving up into S Scotland.