Model Output Discussion - cold spell to end Autumn

[sausage]

30 minutes ago, Daniel* said:

How on Earth are you basing that on GFS 6z alone? 

The EC this morning is much further S similarly ARPEGE model the overall trend is more a southern track compared to one which delivers nothing for the Midlands. 

we dont all live in the south. us northerners would like some snow. we do exist..

[northwestsnow]

6z keeps a generally and cold theme out until the 17th on this run (bar a couple of rainy interludes as the jet swings se into Europe).

We have a pocket of dense cold air across Scandy in FI- i always use that as a potential marker for scandy height rises

edit and there she goes )

Edited December 7, 2017 by northwestsnow

[swfc]

Just as a side note gfs 6z looks a good run imo and an upgrade with heighths building towards iceland!!.sorry for going off topic!!!

[Paul_1978]

40 minutes ago, warrenb said:

What do you expect, it is winter.

 

7 minutes ago, warrenb said:

Can we please stop having sly digs at people and just remark on the models.

Make your mind up Warren! 

[karlos1983]

look at that little wedge of loveliness to the N

Caveat of it's fl, but still nice to see

Edited December 7, 2017 by karlos1983

[tight isobar]

Gfs 6z..

Giving a classic example of large lobe canadian vortex...but rises of heights alingned great ...and linking of pressure rises...@wrap around of heights.....

Russian warmth 'again'...lead player and heights embeded @the pole

Edited December 7, 2017 by tight isobar

[warrenb]

Well BBC have just tweeted snow warning extended south, so maybe the Meto 6z runs are showing a shift the other way.

 

Anyway on the 6z, FI we can see the issue is where is the lobe of PV going to be. Trouble with something that dense, just slight miscalculation by the model will be snowballed.

[warrenb]

1 minute ago, Paul_1978 said:

 

Make your mind up Warren! 

Fair point.

[Man With Beard]

EC 00Z clusters

T96:

5 clusters at D4 lol!! Does seem a growing consensus not to phase the slider too quickly and more agreement on a track a bit more to the SW (good call if right SM!!), which would pull the snow-risk zone south a bit.

T192:

Very good agreement clearly on a fresh Atlantic ridge but looks minor at this stage - weak NWly on its back, snow is going to mount up on high ground...

T240:

A slight shift from last night - looking to flatten out, still in a NWly flow for the UK but Atlantic high anomaly dropping (need more runs to find continuity)

T300:

Seems like a shift to the Atlantic but watch the NE corner on cluster 1 - is an eastern block going to form? Otherwise cluster 2 is westerly dominated, and cluster 3 (minor cluster) is wintry with blocking west and north

T360:

Atlantic too strong on cluster 1 so block to east doesn't happen, but northern heights still in evidence on all three charts.

All in all - there is general much more doubt over a longer term cold set-up, with the Atlantic showing much more energy than of late between D10-D15 - but it's not a complete ensemble flip and bearing in mind this is slightly at odds with previous ensemble runs, it merely increases the uncertainty of what will come after a fresh northerly at D8/D9. 

[Ali1977]

Great GFS Fi, if this happened Xmas Would be very cold. All for fun but not without a chance.

[shaky]

7 minutes ago, warrenb said:

Well BBC have just tweeted snow warning extended south, so maybe the Meto 6z runs are showing a shift the other way.

 

Anyway on the 6z, FI we can see the issue is where is the lobe of PV going to be. Trouble with something that dense, just slight miscalculation by the model will be snowballed.

Is that shift south for sundays slider?

[Daniel*]

10 minutes ago, sausage said:

we dont all live in the south. us northerners would like some snow. we do exist..

Hi sausage,

I in now way have any resentment towards you folk the GFS 06z looks outlandish when comparing to everything else. 

My location is seeing the longest snowless (cover) streak in my lifetime - it’s been almost five years and I’ve seen nothing but a dusting since, we southerners really need to be redeemed. 

[Glacier Point]

.and is if by magic, GFS op in final stages shifts the PV dramatically westwards. Lots of uncertainty approaching I sense as models start to sniff the broad scale shifts upstream. 

[northwestsnow]

Just now, Glacier Point said:

.and is if by magic, GFS op in final stages shifts the PV dramatically westwards. Lots of uncertainty approaching I sense as models start to sniff the broad scale shifts upstream. 

Is the broadscale pattern not conjucive to a +NAO set up stewart?

[Methuselah]

Not bad, for what is (I believe) traditionally one the most mobile westerly spells:

And finishing up with a retrogression signal...not to be take too seriously, though.

Edited December 7, 2017 by Ed Stone

[Glacier Point]

It would not support a +NAO pattern.

GFS op also splitting the lower and middle stratospheric vortex.

[ICE COLD]

Now this is becoming a big trend . Yes I no FI and all that but it was at around 384hrs a few days ago and now it all starts at about 288hrs so it's getting closer . The blog on the BBC website about La Niña ties in with these charts . And they mentioned 2010 ?

Edit : charts wrong way round on dates

Edited December 7, 2017 by ICE COLD

[karlos1983]

For some perspective on the next couple of weeks!

  

Pretty much nowhere in the entire UK has any form of positive value 850's...even on the Costa Del South Coast  Cobra Meeting imminent!

A stark contrast to the previous couple of Decembers 

Edited December 7, 2017 by karlos1983

[ACCOUNT DELETED]

Today it started at 13C at 8.30am currently it's 10C with clear blue skies. Tonight & Friday brings the best chance of snow in Wales except here on the south coast where we may miss the showers altogether with some shelter from northerly winds by the mountains behind us (as is often the case in this set up unless any substantial features form, such as a trough) leaving it dry, cold but sunny. Saturday is mostly dry and sunny but cold again and by Sunday it's now likely to turn wetter (although latest GFS suggests rain won't be as heavy and more patchy along the coast) it'll also become mild again with brisk southwesterly then westerly winds, a high of 11C. Thereafter, colder but drier again from Monday with highs between 5-8C so a little below average at times. 

[bluearmy]

As MWB showed above, the amplified blocked solution on the fi gfs has about 20% eps support which is down from 50% yesterday 00z run and not in line with yesterday’s 12z clustering late on so best to wait for some continuity to take effect 

[shaky]

Regarding slider the arpege is further west again!!gfs maybe out on a limbo here!!

[bradymk]

5 minutes ago, ukpaul said:

No, there are no warnings yet for Sunday at all.

Looking quickly (it is on the metoffice site, which is easy to navigate) it looks like they are now including the Cheshire gap streamer.

Warning now issued for Sunday. 

Thanks for posting clusters MWB, 5 clusters at day 4 shows Sunday is still going to chop and change a bit yet. 

[tight isobar]

27 minutes ago, tight isobar said:

Gfs 6z..

Giving a classic example of large lobe canadian vortex...but rises of heights aligned great ...and linking of pressure [email protected] around of heights.....

Russian warmth 'again'...lead player and heights embeded @the pole

 

[Methuselah]

Given that the models have had this pesky wee LP going into anywhere between the Firth of Forth and the Bay of Biscay, predicting its eventual path must be giving human forecasters on hell of a migraine?

Hey, ho; that's the good old British weather for you!

[Singularity]

 

Slight shift south from the ARPEGE 06z, what a shame it stops at +72 eh? 

Given this and the 00z ECM and allowing for typical uncertainties, it seems the low centre could yet go anywhere between Cornwall and the Scottish border. Helpful, I know