Model Output Discussion 23/11/2012 18Z onwards

[LomondSnowstorm]

So Far so good that low(spoiler ) not showing up

Spoke to soon it's firing up at 120 , lets hope it gets pushed back

The trough is further south on this run though which will be a big help and in fact we could maybe even get away with the link up if it were far enough south.

[Cheshire Freeze]

18z ejects some energy SE but not as much as the 12z.....MIGHT get away with it this run.

[cold snap]

The trough is further south on this run though which will be a big help and in fact we could maybe even get away with the link up if it were far enough south.

The low had got in again messy picture again at 144

For the love of god

[If Wishes made Weather]

Pushing 15cm of rain by next Wednesday for a swathe of the north midlands on this run.

Presumably the local councils/fire depts have all staff on standby, reserved crews waiting by the phones, school/village halls open etc? From that modeling, the Severn and the Trent will be taking a big rise.

[Nick F]

Still that energy sliding SE under the block to the N over Iceland/Sern Greenland on 18z - which kind of still interfering with the low over Europe and preventing the coldest air heading SW towards the UK, but it may only be a delay to the cold reaching us.

But I echo the concerns re the potential for serious flooding from persistent rainfall this weekend and again early next week. This is a serious situation potentially unfolding before our eyes ...

Edited November 23, 2012 by Nick F

[Geordiesnow]

Difference between the GFS and UKMO is the GFS is sourcing our easterly winds from eastern Europe whereas the UKMO is sourcing them Scandinavia hence the GFS is milder whereas the UKMO looks promising for cold!

You got to also say how messy these blocking charts seem to be nowadays, lots of squiggly lines whereas well in the past, cold blocking set ups look a lot more organised and much less shortwaves.

We are so close on this run being perfect for cold aswell. We better hope the UKMO is onto something here!

[cold snap]

Still that energy sliding SE under the block to the N over Iceland/Sern Greenland on 18z - which kind of still interfering with the low over Europe and preventing the coldest air heading SW towards the UK, but it may only be a delay to the cold reaching as.

Looks like you might be right much better now it's been chewed up lol

Block starting to rebuild

[snowking]

Well GFS by 138 looking very similar to ECMWF 144

[Zenarcher]

My eye has been taken off the potential cold and onto the rain. This really is a serious situation - a disastrous amount over the weekend for parts of the S (SW esp), added to what they already have, and then 36-48 hrs of heavy rain for NMids (18z) or N Eng (12z). Worrying.

18z has certainly upgraded that low and now looks similar to the ECM

Gust charts show the South and South East getting very high gusts,

[Cheshire Freeze]

GFS looking good at 156.....cold uppers flooding south.Really knife edge stuff though and in no way a clean evolution to cold.

[EML Network]

I've a feeling this run is going to go down in the record books as being the most eventful in since ..well...ever ;-)

There's something going on, almost every day, whether it be high winds, rain, cold or even snow potential, we really are being treated to the most fascinating period of model watching for a long long long time, as others have said...enjoy the ride...but do take care out there , some extreme events look likely over the next 5 days and possibly beyond.

[cold snap]

This is getting better and better after a dodgy time at 144 could be Stella

[Cheshire Freeze]

Well GFS by 138 looking very similar to ECMWF 144

Better than the ECM at 168....heights in the Atlantic looking more robust, cold flow across the UK

[If Wishes made Weather]

May I suggest that the 18z is 'cleaner' than the 12z up to T135ish. Interestingly it remains interested in siting the low pressure system over Mecklenburg and hence the air flowing around its top is coming into us on a NNE feed. Yesterday's model put this further south allowing more of an Easterly feed. However, compared to the 12z is doesn't drop the low to such a deep pressure. Also the mid Atlantic low is not showing on this run, rather a ridging high pressure to Greenland which must (I suppose) be a positive and cleaner picture.

[snowking]

I must say, from a snow point of view, I very much like the GFS evolution here post 144....we actually end up in a very similar situation to what we've had this week in terms of the rotation of LP systems bringing constant precipitation, the difference this time being that the trough is set up to our east, and we end up with cold embedded uppers

Still a bit of a risky evolution (need to hope that we don't get too much energy heading SE a la 12z) but rewarded later

SK

[Geordiesnow]

Well GFS by 138 looking very similar to ECMWF 144

Yep, this run does look similar to the ECM which although not a disaster, its not great either as the 18Z also wants to send the trough into Scandinavia therefore pushing milder uppers into Scandinavia therefore getting rid of any cold easterly potential.

That said, the Northerly should be colder and the blocking is still there so its hardly a disaster but I hope the models back away from sending the trough into Scandi though, it would be just typical if we have to start again so to speak.

[chionomaniac]

Is that a polar low at T+174?

Edit - sorry that was a joke before I get 10 replies discussing polar lows!

Edited November 23, 2012 by chionomaniac

[Chris D]

Yes GFS looking AWESOME now!!! T174 oooses potential.

Steve...bin? hahaha

Edited November 23, 2012 by Chris D

[NickR]

Yep, this run does look similar to the ECM which although not a disaster, its not great either as the 18Z also wants to send the trough into Scandinavia therefore pushing milder uppers into Scandinavia therefore getting rid of any cold easterly potential.

That said, the Northerly should be colder and the blocking is still there so its hardly a disaster but I hope the models back away from sending the trough into Scandi though, it would be just typical if we have to start again so to speak.

Yes. The winds end up veering NNW'ly too - cutting off the sub -7 uppers and limiting snow to N Scotland mainly.

[liam300]

I would say the 18z is a downgrade in regards to 850 pha as the pressure keeps the -4 to -6 away from the east and south east. This is around the 28th - 29th, although +144 shows potential

Edited November 23, 2012 by liam300

[Severe Siberian icy blast]

Putting aside the obvious northern blocking that's great, I genuinely fail to see that trough setting up shop in RUSSIA not France like every teleconnection points it to, normally I would say its plain wrong although this is a consistent theme on the models, but If that is how it end up then the general signals of the positioning of the trough is way out . Not moaning just saying what I see, and not saying it means no cold or snow, I'm simply saying its consistently putting the trough to the far north of Europe rather than France.

[Mucka]

I would say the 18z is a downgrade in regards to 850 pha as the pressure keeps the -4 to -6 away from the east and south east. This is around the 28th - 29th, although +144 shows potential

Downgrade to what? It is a lot colder than the 12z at the same time.

[ukpaul]

The difference in wind direction would make this dry apart from west facing coasts.

Better 850's for the south east though so most definitely a colder run.

[ITSY]

very happy with that evolution, sets up the cold nicely. a couple of things worth saying though: a) horrific amounts of rainfall coming up for areas that just don't need it and b ) any snow potential is still not any closer than t+168. i know its early days, but that has been the same for the last 3/4/5 days now so is worth noting IMO.

EDIT: collapse in FI...the 2nd operational run in a row...it shapes up well for a reload, which may well be nothing to complain given the messy synoptics, but Atlantic/Azores seem to be having more of a say for GFS today.

EDIT 2: Having said that, the uppers across the bulk of the country don't get above -4 for the bulk of FI, we end the run with a superb reload (and a greenie in waiting), uppers of -8 AND i think GFS overcooks the warm sectors meaning that much of what is shown as rain would actually be snow given the air they are bumping into. All in all, I would take that set-up if it were offered.

Edited November 23, 2012 by ITSY

[bobbydog]

we had a little flurry of activity from our irish contingent earlier- did they have a sneaky preview of the 18z?.....