Model Output Discussion - 05/01/2016 18z onwards

[Eskimo]

3 minutes ago, Neilsouth said:

This is from the Met via twitter, doesn't look all that cold to me?

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Edited January 11, 2016 by PerfectStorm

[Day 10]

The rollercoaster shows no sign of stopping then

Who will be right this time???

[The PIT]

GFS quite bullish about bringing the Atlantic through after Sunday.  UKMO at T144 doesn't show the same but really too far out to take either as correct without a pinch of salt

[Cheshire Freeze]

As CS has pointed out and as I said last night, for as long as these attacks on the vortex continue, we'll see blocking features wax and wane within the NWP. I agree that perhaps an easterly will pop up at short notice.

[Timmytour]

I'm not sure the GFS variations on a run to run basis are that great...it's just that this is a set up where little differences can make a great deal of difference to the weather we experience.  If this were late spring, summer or early autumn it would be a case of how much rain we end up getting and no one would be taking too much notice

[phil nw.]

GFS loses any UK high by the weekend which seems very fast compared to the ens outputs which hold our cold high into next week.We would be into a sw drift by day 6 on the 12z.

This seems questionable to me considering the previous runs and the 12z UKMO at T120 even.

 

UKMO again has much better ridging which would certainly extend the cold into week 2.

GFS generally in this current setup seems reluctant to hold onto Atlantic ridging after around day 5 but as it get's closer it seems to find some again.

I always try to look at the bigger(hemisphere)patterns too.One feature to note is the continued presence of the Siberian ridging(Kara sea} into the Pole.

It has 2 benefits-- 1.continues to undermine the vortex and 2.holds the cold upper trough in place to our east.This may well come into play if the Atlantic jet weakens further and we see our high building further north bringing a bitter polar continental flow from the area around Scandianvia/N.Russia.There is a mighty large area of cold there just waiting.

It is certainly giving the models some problems as the lows come up against the cold block.We have seen and continue to see the messy trough disruption around our locale.

Many of us have noticed that deep cold air further north which has been bordering the N.Isles for weeks now and this now is finally working it's way south to affect all of us in 2/3 days.

As JH says historically those deep cold pools are not easily shifted especially with signs of a vortex continually being attacked by warm air advection around it's edges.Under these circumstances a quick return to mild south westerlies seems a longer way off than GFS 12z run is showing this evening.

The roller coaster goes on as we await the ECM later.

[warrenb]

1 minute ago, Timmytour said:

I'm not sure the GFS variations on a run to run basis are that great...it's just that this is a set up where little differences can make a great deal of difference to the weather we experience.  If this were late spring, summer or early autumn it would be a case of how much rain we end up getting and no one would be taking too much notice

Take a look at the NH view, and you will see the whole picture. Completely different each run.

[Catacol]

Evolution this week is fabulous. Arctic air mass sucked over the uk.... pressure rising to help lock surface temperatures in place (cold) and help cool everything down nicely. 3 - 5 day cooling down period was what I was hoping for, and it looks like it will arrive. Snow bonus on Thurs/Fri for the south is probably unlikely.... but a few flakes in the air would be nice as a starter...

Into next week fingers crossed continued amplification will see the ridge maintained to our north (best case) or at least over us (not best case but not bad...) and then - when the torpedo lands in just under 2 weeks time - we can get a proper high lat block in place and either an undercut pattern from the west or a European easterly. Personally I'd prefer the undercut, but fronts from the SE will do too.

Great watching the models - I love seeing the GFS wriggle all over the place with no idea where its at. Gives me a warm fuzzy feeling cos you know when the models are struggling that it is blocking they are struggling with - and that is always good winter news.

Any chance of this fun being spoiled? Well - I dont think so. Cant see amplification falling sufficiently to allow the HP to sink back to our south - Tamara's post today has helped reinforce that feeling and increase the warm fuzzy feeling... but I guess it is always an outside chance. But even if it did happen I suspect it wouldnt last long. Renewed surge of heights to a decent latitude looks the form horse to me as we move into the last third of January. 

[Jason M]

Gem control and ensembles mostly have heights to our NW. Hardly any support for GFS at all (or indeed the GEM opp). That said, you can't ignore the opp runs at these time ranges even if they are wildly different from their ensembles.

 

 

 

Edited January 11, 2016 by Jason M

[A.J]

quite a few posts moved/removed............can we please keep met office forecasts and stratospheric related posts to the relevant threads please....thanks

[stratty]

...... plenty better ensemble members for snow down south for end of week - here's one:

http://www.meteociel.fr/modeles/gefs_cartes.php?code=20&ech=102&mode=2&carte=0

[Dancerwithwings]

24 minutes ago, feb1991blizzard said:

When it comes to complex setups delivering cold into the UK, 144 as always been fi in terms of operational runs.

How true that is,  we never had that issuse in December! ...... So, so glad it's behind us 

[Liam J]

7 minutes ago, Jason M said:

Gem control and ensembles mostly have heights to our NW. Hardly any support for GFS at all!

 

 

Yeah the control is very cold well into next week, the GEM OP goes quickly downhill much like the GFS OP after the weekend so it does have support... I'd be more worried if the ECM followed the GFS though! 

Edited January 11, 2016 by *Sub*Zero*

[JOPRO]

20 minutes ago, PerfectStorm said:

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I wouldn't worry about those temps to much, we have been a good 1-2 degrees below at times what we where supposed to be today according to the bbc. Gives me a little bit of optimism regards Wednesday PPN and the chance of some surprise snowfall.

[Mucka]

This is the sort of pattern I am hoping for which are variations on a theme - the Atlantic trough disrupting SE instead of the Atlantic just surging through which would maintain some heights over Greenland and hopefully encourage another bout of WAA toward Greenland behind.

Not showing within the mean so not that well represented as yet unfortunately.

[Hotspur62]

Well the only thing  the models are consistently showing is their inconsistently showing agreement!!GFS has consistently shown the Atlantic pushing through with milder temps returning to UK. The UKMO is having none of that and we await the ECM.

 

FWIW I feel this will be a coldish spell but nothing what most on here wish for. The good thing is that a cooling trend is occurring and Northern England Northwards are looking favoured to seeing snow. Further South I feel snow is only likely in elevated areas of 150m+. That is just my take on the likely outcome from past experiences when we have been in similar set ups ( I appreciate no 2 set ups are ever the same.

Moving on there really are all possibilities on the table varying from milder Westerlies which Met Office seem favourite looking at their latest forecast. Then if you read Tamara's and GPs views it would appear that something more colder is possible with attacks on the Vortex maybe resulting in what 99% on here would like..

If this is to happen this is most likely in latter January and hopefully run into February.

My favoured outcome would be for Tamara's and GPs views to come to fruition as this would be one happy forum but my 'Gut" feeling is the Met Office will be correct as they haven't ben too far off the mark so far this winter( Mind you if this cold snap/spell does materialise they weren't that good on picking up signal imo).

Fascinating stuff and very addictive model watching which I am sure will have us on the edge of our seats and watching behind sofas lol!!      

[northwestsnow]

http://www.wetterzentrale.de/pics/Rukm1441.html

Can't find much wrong with that chart, if only we could bank it now!!

[nick sussex]

Good grief the GFS is still refusing to back down. The UKMO is excellent but you can clearly see the differences upstream between the GFS and the UKMO between T96 and T120hrs. The UKMO phases the low running east over the USA  with the PV lobe and has a more amplified pattern which sharpens up the troughing to the west.

The GFS keeps the south/north jets separate and is much flatter which then sends the energy eastwards.

I'll see what NCEP has to say re the upstream pattern, lets hope they don't favour the GFS!

[fromey]

fergieweather

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Posted 9 hours ago · Report post

 

 

I have just copied pasted this from the south west discussion  

 

no output should be taken at face value especially when our own met office are saying the models are struggling  

Chilly start! Well, an interesting few days coming-up... especially given how modelling is struggling with nearer-term features, with confidence low into medium range. Indeed, just last night UKMO noted how a combination of factors *could* mean effectively colder conditions being in-situ across the next 15 days (note models inevitably lean to shunting colder blocks aside far too quickly). So, we might be in a bit of a rut for at least a while, trying to nail-down awkward local detail when it comes to rain v sleet v snow. Forewarned and all that....!!

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[nick sussex]

Right theres a lot of uncertainty re the pattern in the eastern USA:

PATTERN OVERVIEW... THE LARGE-SCALE PATTERN IS DOMINATED BY A BLOCK OVER EASTERN CANADA WITH A BROAD YET COMPLEX LOW SUSTAINING A MEAN TROUGH ACROSS THE GREAT LAKES/OH VALLEY. MEANWHILE...THE WEST IS LARGELY INFLUENCED BY FAST MOVING SHORTWAVE TROUGHS EMBEDDED IN THE STRONG FLOW OVER THE PACIFIC THAT ARE BREAKING THROUGH THE NARROW MEAN RIDGE ALONG THE WEST COAST. INTERACTION OF THE WEST COAST STREAM WITH PERTURBATION ROTATING THROUGH THE BASE OF THE GREAT LAKES TROUGH LEADS TO GROWING UNCERTAINTY EAST OF THE MISSISSIPPI RIVER DUE TO POSSIBLE INTERACTION OF THESE STREAMS.

You'll see they mention streams, given the set up we must really see those streams interacting like the UKMO.

Theres better news though as to what they think of the GFS:

THE MODEL CONSENSUS IS THE SECOND ASPECT...WHICH FAVORS A MORE SOUTHWARD UPPER LOW NEARING MINNESOTA BY FRI/SAT VERSUS THE MORE NORTHWESTWARD GFS...AS WELL AS SUGGESTING SLOWER TIMING FOR THE SHORTWAVE TROUGH NEARING THE WEST COAST. THE THIRD ASPECT IS MODEL BIAS. THE 00Z GFS MAY BE DISPLAYING ITS FAST BIAS ALONG THE WEST COAST BY SAT...AND MAY BE OVERDOING ITS NORTHWESTWARD POSITION FOR THE UPPER LOW NORTHWEST OF MINNESOTA BY UNDERCUTTING THE UPPER HIGH TO ITS NORTH... BEHAVIORS THE GFS OCCASIONALLY DISPLAYS. THESE ASPECTS WHEN COMBINED FAVOR AN OVERALL SOLUTION SOMEWHERE BETWEEN THE 00Z ECMWF/00Z ECMWF ENSEMBLE MEAN/06Z GEFS MEAN...WITH THE ECWMF/ECMWF ENSEMBLE MEAN CAMP MORE HEAVILY WEIGHTED.

These discussions are in relation to the 00hrs outputs however the issues raised there are still on the GFS 12hrs run.The pattern in the Pacific is important because its the more amplified set up there which downstream helps the pattern in the eastern USA. The GFS throws shortwave energy through that upper high much quicker than the other outputs.

 

Edited January 11, 2016 by nick sussex

[SLEETY]

12 minutes ago, northwestsnow said:

http://www.wetterzentrale.de/pics/Rukm1441.html

Can't find much wrong with that chart, if only we could bank it now!!

surely that would lead to a big easterly incoming !!! ,love to see a 168 chart

[stratty]

Incoming 'torpedo'! http://www.meteociel.fr/modeles/gefs_cartes.php?code=19&ech=384&mode=1&carte=0

[MR EXTREMES]

gefs  looks like it wants to displace residual vortex energy over this side of the hemisphere going forwards and id reluctantly say that the jet at some point beyond 180 would be heading futher south which could open the door to another height rise into Greenland in time.

ukmo is pretty good tonight and the comments made by ian f and tamara,s also shows continued possibilities 09/10 didn't start and stay cold it had reloads and this could well happen through the rest of winter.

as suggested by john h theres plenty of years that the models try to remove enriched cold swiftly out the way only to be forced back or held back leading to slow snowy breakdown or reload or just cold heights like that has been shown by other models.

either way 4 or 5 days of cold wont be shifted like you may expect unless of coarse the models are wrong in earlier timeframes there for not seeing that the current cold setting in is futher east  than the models expected.

but then again they could be futher west than expected its now coming down to now casting time anything can happen.

Edited January 11, 2016 by emotional rollercoaster

[Singularity]

Look at that small low between the deeper one over the U.S. and the shallow one over the Azores. GFS merges it with the U.S. feature while UKMO merges it with the Azores feature. This adds to the differences already arising from disagreement over the jet behaviour as noted by Nick S.

Looking back, ECM's 00z det. actually went the way of the 12z UKMO with respect to which feature the low merges with, but differences over the Arctic (some instability moving to the pole then interacting with the U.S./Canadian trough) and I suspect a lack of north/south jet phasing (I was elsewhere this morning so missed the discussions and haven't got time to read all the way back) allowed the Atlantic trough to blast through regardless, despite a promising looking +144 chart. 

Coming back to the UKMO run, it just keeps on giving out to +144, with a residual low over the Azores attempting to undercut the ridge which itself is still west of the UK (hints between the lines from Fergie that the Met Office consider this holding back west a real possibility), and some deep troughs over Europe while that area of lower heights over Svalbard is departing for the Pacific, opening up the possibility of a bridge between the Atlantic ridge and the Siberian High. 

We do seem to be in a situation where anything from a notable cold spell to a few wintry days followed by blowtorch southwesterlies makes up the range of genuine possibilities.

Imagine the impact an ECM 12z det. run that depicts favourable U.S./Canadian trough behaviour would have on here - let alone if we got that negatively tilted merger with the Azores low as well!

[northwestsnow]

Fergies update is extremely interesting, esp the comment about not ruling out cold regime for the next 15 days.

Dare we hope?:

FWIW it would seem to me we have ukmo and gfs churning out two extremes with ecm in the middle.Unfortunately there is no middle ground insofar as the weekend and beyond is concerned - we need the ecm to look EXACTLY like ukmo144 tonight.