Model Output Discussion - cold spell to end Autumn

[khodds]

Are we still thinking thunder snow may be a possibility on Thursday with the temperature drop? 

[comet]

16 minutes ago, abbie123 said:

BBC saying staying cold in to next week  with  further snow ..

I hope he is right but unfortunately that does not mean a great deal. I am quite sure you yourself may have seen a snowy picture at the start of a bbc weather bulletin with the wording snow on the way tomorrow and yet when he gets into the forecast the only places likely to see snow were the Scottish highlands. Talk about misleading.

Anyway still holding out a slim hope of the slider Sunday into Monday may take a more favourable path for those of us down south and also the possibility of seeing a few flakes during Friday into Saturday. If the GFS is to be believed then it shows it is still possible to get potent northerlies even so early into the season.

[bluearmy]

3 minutes ago, northwestsnow said:

Blue which was better rgding snowfall distribution? 

For the initial feature, definitely today whilst by day 9, today's is just better. If I was living north of Birmingham away from the twenty miles by the coast, I would be getting very interested. the area around Buxton looks to be close to 9 inches by the end of Monday although this is probably overstated as per nicks posts earlier 

[Catacol]

3 hours ago, ShortWaveHell said:

So reading the thread after work ... some ultra respected and knowledgeable netweather contributors suggest this month is one of the more interesting ones for many a recent year,  In terms of some signals  , then the whole December pattern has changed to zonal due to the GFS 12z run today , I’m at 6s and 7s as a novice to say the least 

Just one observation from me on this - and that is that the models are not doing a good job of resolving the current situation regarding AAM. Schiraldi plots freely available here 

http://www.atmos.albany.edu/student/nschiral/gwo.html

can be run over the previous 5 days - and GWO amplitude is being consistently undermodelled... and sometimes by quite a bit at very short range. My take on this - for what it is worth as I am absolutely an amateur and not a pro - is that the models are underestimating the extent of pacific forcing, perhaps expecting the Nina signal to dominate things, but as Tamara has eloquently put this afternoon we are perhaps (emphasise perhaps) approaching a period where the Nina base state is under challenge. Perhaps this is down to the very east based nature of this Nina... perhaps part of an interplay between this and a weakly positive PDO - but whatever the cause it appears to be challenging the models, and in terms of poleward energy pulses we have an unusual setup for a Nina year.

So - to be blunt: I wouldnt pay any attention at the moment to op runs based on false reading of the signals upstream. This isnt to say that we are destined to remain on the cold side of the polar jet as it wobbles and curves - we could conceivably end up on the mild side as will happen ever so briefly tomorrow - but I just dont see the start of a flat pattern yet. 

But Tamara was bang on - we have to wait to see exactly how long this unusual situation lasts. If it gets any longevity, and Tamara suggested a look in the 10 day bracket would be telling which seems about right, then all bets are off in terms of a "standard" Nina pattern that would see cold as front loaded through winter. However if we get a sudden dip in AAM - and the models today over on cpc continue to think that the MJO will dive to the COD (but every day pacific convection continues to stick 2 fingers up at that idea...) then a flatter jet ought to be the result.

Which brings me back to my original point made earlier today - this is fascinating model and teleconnective watching. Note I didnt say we were destined for cold and snow (though I freely confess to loving seeing snow fall) but that we should really be enjoying this. We could so easily be staring down the barrel of gentle mid atlantic topplers battered by a flat jet and potent strat led vortex. The fact that we have something so very different is bringing me back to models and this forum more than once a day and, despite the daft ups and downs of those who see op runs as things to be worshipped, it is pretty riveting at present.

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

On 04/12/2017 at 18:07, Draig Goch said:

18z rolling out now

[karlos1983]

If the gfs 18z shows snow to the south can we southerners please all bang on about it for hours on end. Thanks in advance 

Not that I’m bitter or anything  

Edited December 5, 2017 by karlos1983

[MattStoke]

4 minutes ago, karlos1983 said:

If the gfs 18z shows snow to the south can we southerners please all bang on about for hours on end. Thanks in advance 

Not that I’m bitter or anything  

You will be....

We all will be 

 

[frosty ground]

More of a westerly element for NW England

[Catacol]

Incidentally - while we await the next run - EC monthly has a sustained signal for -AO and a jet firing south underneath heights to our north. This right out to January. Greenland positive anomaly continues plus a build up of heights in northern Russia. Has a very Murr sausage look about it..... :-)

[Paul_1978]

Am I in some kind of parallel universe or what? We'd have given our right arms for charts like this last winter. And the winter before. And the winter before. 

These charts are being turned out regularly. It's brilliant to watch. 

Edited December 5, 2017 by Paul_1978

[weirpig]

gfs going off on one  Cheshire streamer hitting Calais 

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5 minutes ago, Catacol said:

Incidentally - while we await the next run - EC monthly has a sustained signal for -AO and a jet firing south underneath heights to our north. This right out to January. Greenland positive anomaly continues plus a build up of heights in northern Russia. Has a very Murr sausage look about it..... :-)

[Nick F]

5 minutes ago, weirpig said:

gfs going off on one  Cheshire streamer hitting Calais 

Well, the 12z had a Cheshire Gap streamer reaching West of London, just a little bit further SE this time!

Edited December 5, 2017 by Nick F

[weathermadbarnsleylad]

-10 850s hitting east Anglia in 66hrs brrrr

[ArHu3]

7 minutes ago, Paul_1978 said:

Am I in some kind of parallel universe or what? We'd have given our right arms for charts like this last winter. And the winter before. And the winter before. 

Theae charts are being turned out regularly. It's brilliant to watch. 

We had plenty of nice charts last year but when they got to 120-144h they always got downgraded to meh

[shaky]

Hmm.slightly stronger ridge ahead of the shortwave at 84 hours!!

[Day 10]

The high ridging a little higher

[Timmytour]

10 minutes ago, Catacol said:

Incidentally - while we await the next run - EC monthly has a sustained signal for -AO and a jet firing south underneath heights to our north. This right out to January. Greenland positive anomaly continues plus a build up of heights in northern Russia. Has a very Murr sausage look about it..... :-)

Trying to remember what it showed a month ago for now...

[karlos1983]

Early doors the ridging ahead of the proposed slider is better. This should hopefully result in a more southerly track. Not enough for me I wouldn’t imagine, but that’s life. I’ll get over it. Eventually 

 

Edited December 5, 2017 by karlos1983

[nick sussex]

This looks a bit different with the shortwave break away earlier, could be interesting! Looks like a sw correction coming up with a slightly better upstream profile.

[tight isobar]

get any slider under that jet... 

and its rapid snow conversion.. 

850s playing ball almost countrywide!!!

18z off to a cracker!!!..

this slider going more southerly??!!

Edited December 5, 2017 by tight isobar

[Methuselah]

Is this more of a northerly? Or is it just wishful thinking?

Edited December 5, 2017 by Ed Stone

[I remember Atlantic 252]

Just now, Ed Stone said:

Is this more of a northerly? Or is it just wishful thinking?

Hopefully just wishful thinking Ed

[damianslaw]

Over the past couple of days I've said keep an eye on developments to our NE, as there is a good chance as we move through the middle of the month that heights will build here thanks to another amplification of azores high towards Greenland later next week, with a deep trough sinking down through Scandi. Signs of this being shown in GFS model today.

My taking on things, an arctic blast Fri-Sat, a slider low on Sunday, slightly milder conditions early-mid next week, more so in the south, with the north holding onto the cold air and therefore chance of more snow here, then the azores high ridging north again thanks to a deeper trough moving SE through UK middle of next week, this then allows height rises to our NE to begin to nose SW, and a link up of heights to our north as we enter the week leading up to christmas.

A predominantly cold outlook for the north, with a temporary milder phase for the south lasting about 4 days (12-15th).

 

[The Beast From The East]

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Edited December 5, 2017 by TheBeastFromTheEAST