Model output discussion - heading into 2018

[gottolovethisweather]

38 minutes ago, nick sussex said:

Quite a big change in the UKMO with the T72 hrs bringing another possible snow event running nw/se across the east and ne.

Unfortunately any snow won’t last long with milder air pushing east after that but there seems to be a lot of uncertainty with how this cold snap breaks down .

6

In Costa Del Newbury,  these days, any snow is good news. Especially if there are temporary accumulations. Could be two such instances before the turn of the year, that alone is something for coldies like me to celebrate. One mild day before the turn of the year on Saturday is the forecast currently it seems, alongside a few bouts of wintry mixes of rain, sleet or snow. I'll take that with open arms, given the mild dreary dull dank episodes of late, hopefully some brighter skies in between.

 

Edited December 26, 2017 by gottolovethisweather

[Daniel*]

I’ve seen a lot worse a wintry start to 2018 for the far north, a frost for nearly all to greet 2018 could be quite a severe one with the winds so light. There seems to be less of an inclination to revert to standard fare. 

[Weather-history]

1 hour ago, Weather-history said:

Note the "higher" pressures anomaly runs towards Newfoundland. That suggest to me, polar maritime airmasses maybe more frequent or easier to reach the UK. If that low pressure anomaly around Iceland extended towards Newfoundland then polar maritime airmasses would really struggle.

GFS 12z op run is a polar maritime fest 

[Tim Bland]

Despite the lack of exciting Synoptics there are still pleanty of snow opportunities showing up. After tomorrow there is Thurs which is shown well by the GEM precip chart. A northerly for New year is shown on UKMO and a Channel low on GFS for nxt week, which could deliver if uppers are a bit lower! 

 

[Northern Sky]

Maybe no deep cold on offer but the GFS12Z is pretty much cool/occasionally cold almost throughout. Certainly no blowtorch SW'lys evident on this run.

[nick sussex]

Something to bear in mind re the upstream differences between the GFS and others.

NOAA have dismissed all GFS and GEFS solutions , none have been incorporated into their medium term outlook.

Their outlook has been derived from 80% ECM ensembles , and 20% the ECM op run.

[feb1991blizzard]

2 minutes ago, nick sussex said:

Something to bear in mind re the upstream differences between the GFS and others.

NOAA have dismissed all GFS and GEFS solutions , none have been incorporated into their medium term outlook.

Their outlook has been derived from 80% ECM ensembles , and 20% the ECM op run.

Not good news then, the GEFS look more promising to me (around 192 PM air), ok neither suites are showing bitterly cold runs in any quantity but i'd take the GEFS.

[karyo]

2 minutes ago, nick sussex said:

Something to bear in mind re the upstream differences between the GFS and others.

NOAA have dismissed all GFS and GEFS solutions , none have been incorporated into their medium term outlook.

Their outlook has been derived from 80% ECM ensembles , and 20% the ECM op run.

Nick, have they dismissed the 12z GFS or the earlier versions? If the 12z was to verify I wouldn't be complaining. The 6z though was a horror show for cold.

[feb1991blizzard]

IN fact I take part of that last comment back based on the current GEFS, they aren't just showing marginal PM slushfests, a good number look like they might go on to show much more amplified solutions in the 15d range.

[nick sussex]

2 minutes ago, feb1991blizzard said:

Not good news then, the GEFS look more promising to me (around 192 PM air), ok neither suites are showing bitterly cold runs in any quantity but i'd take the GEFS.

That only covers upto day 7.  There are a lot of timing differences and NOAA didn’t think much of any of today’s GFS op runs or GEFS.

Their outlook doesn’t include tonights ECM they were talking about the 00hrs.

The GFS has slowed a little since its earlier runs but is still the quickest upstream .

We really need more of an inland storm upstream as that will build a better upstream ridge ahead of it.

[northwestsnow]

3 minutes ago, feb1991blizzard said:

IN fact I take part of that last comment back based on the current GEFS, they aren't just showing marginal PM slushfests, a good number look like they might go on to show much more amplified solutions in the 15d range.

Great news feb..

[nick sussex]

Looking at all the 12hrs outputs so far I’d bin the GFS 12hrs op.

Its so out of synch with the rest I can’t imagine it’s correct and seeing as both the UKMO and GEM have both moved towards the ECM 00hrs run then that looks the trend setter upto day 7.

 

[feb1991blizzard]

16 minutes ago, northwestsnow said:

Great news feb..

Probably not as good as I thought - apart from brief PM shots there's no real coherent signal of anything dead cold.   Still decent enough for some people but I'm just fed up with these marginal slushfests.

[northwestsnow]

1 minute ago, feb1991blizzard said:

Probably not as good as I thought - apart from brief PM shots there's no real coherent signal of anything dead cold.   Still decent enough for some people but I'm just fed up with these marginal slushfests.

Well im afraid you have compounded things by moving to the north west!!

Lets see what EC comes up with..

[karyo]

12z ECM similar to the UKMO with the wave feature so a snow event possible on its east and north side.

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=0&type=0&archive=0

[northwestsnow]

2 minutes ago, karyo said:

12z ECM similar to the UKMO with the wave feature so a snow event possible on its east and north side.

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=0&type=0&archive=0

Thats good!

Bad news its all going to be washed away a few hours later.

I cannot get 'up' for a snow to rain 'event'.Personally it just smacks of how desperate we have become.

[MP-R]

4 hours ago, Catacol said:

The MetOffice is as good as any I reckon:

https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/el-nino-la-nina

If you look at the November graphs they have helpfully added the December stats so that you can see the actual progression still sits in the middle of the ensemble forecast runs. Essentially still a weak Nina, though regions 3 and 3.4 get closer to moderate than we would like.

All forecasts still seeing the bottom of Nina arriving prior to the end of January. There is some hope, therefore, that the next tropical convection wave may find conditions a little easier to progress through to phase 8 by February.

Many thanks! My hopes are pinned on the second half of January for a proper cold spell. As we know, an Atlantic spell with a southerly jet can also bring interest, and sometimes more snow than deeper cold. Here's hoping. The models really are showing no two days being the same.

[karyo]

The ECM fails to properly develop the high pressure ridge thanks to residual low pressure around Iceland. The 0z was better at this stage.

http://www.meteociel.fr/modeles/ecmwf.php?ech=144&mode=1&map=0&type=0&archive=0

[northwestsnow]

30 minutes ago, karyo said:

The ECM fails to properly develop the high pressure ridge thanks to residual low pressure around Iceland. The 0z was better at this stage.

http://www.meteociel.fr/modeles/ecmwf.php?ech=144&mode=1&map=0&type=0&archive=0

Its a dreadful run K.

Flat as a pancake across the Atlantic.

[karyo]

2 minutes ago, northwestsnow said:

Its a dreadful run K.

Flat as a pancake across the Atlantic.

I can take it up to 120 hours but after that it is terrible. Still we may see some slush on Friday morning! 

[Weather-history]

11 minutes ago, northwestsnow said:

Its a dreadful run K.

Flat as a pancake across the Atlantic.

Not exactly terrible for parts of Scotland, the point I was making about higher pressures around Newfoundland also holds true  for this run as well. It is one of key components of cold zonality

 

Edited December 26, 2017 by Weather-history

[knocker]

A closer look at this evening’s ecm det. output post the passage of the current low.

By Wednesday evening a northerly covers the UK thus a much colder airmass than of late but as the low continues to track east a very slack pressure gradient becomes temporarily established resulting in a very cold day on Thursday with temps struggling to get above 3C (of course there are exceptions)

But by 12 Friday the Atlantic is getting more organised and a front with a little wave (centred over northern England) is crossing the country with sporadic rain in England and Wales, perhaps some snow on northern hills.

This quickly clears east but a major upper trough is now dominating the Atlantic with a strong jet leaving the eastern seaboard and sweeping across the southern UK thus the next frontal system with heavy rain is already affecting the south west by Saturday 00. This clears the east coast quite quickly during the morning but lingers longer over Scotland as the low tracks just west of the Hebrides. This could well produce snow in Scotland and even the north of England as there is a very marked temp boundary across the UK

The front eventually semi clears Scotland but there is a large and very complex low pressure area to the west with little low centers everywhere and a shortwave  has formed in the southern quadrant which tracks rapidly east to be over south west Scotland by 00 Sunday en route to the North Sea bringing some heavy rain to N. Ireland, northern England and southern and central Scotland with possibly snow on the high ground, Strong winds and gales, perhaps severe in places, are also a feature of these systems over the weekend.

The decks are finally cleared to the east with the wind veering northerly on Monday but briefly as the Azores starts to ridge north east which in turn comes under severe pressure once again from the energy rushing north east from the eastern seaboard and by Wednesday 00 more fronts and heavy rain accompanied by strong winds are already into western parts.

The 6-10 anomalies

[ANYWEATHER]

1 hour ago, feb1991blizzard said:

Probably not as good as I thought - apart from brief PM shots there's no real coherent signal of anything dead cold.   Still decent enough for some people but I'm just fed up with these marginal slushfests.

Well perhaps your glass is half full or half empty

[SLEETY]

Very windy and stormy looking ecm run,but nothing remotely cold showing,oh well maybe things will change after first week of jan,as some posters have alluded too

Edited December 26, 2017 by SLEETY

[Singularity]

MJO looks to become a player again in the mid-longer term but this time while over the Indian Ocean. 

Basic composites for these phases support the mobile westerly theme for a phase 2 response, but then suggest troughs should tend to dig well down into Europe for a phase 3 response. 

This is not adjusted for La Nina conditions though (let alone east-based variant of that) - I've not the togetherness of mind to put that  together at the moment 

What if the MJO propagates eastward from there? Well, unfortunately for us, that would favour westerlies again during phase 4-6 propagation - but on the flip side, the phase 5-7 propagation would be great for poleward ridges driving vertical wave advection to disrupt the vortex. 

 

Hopefully it can get all the way around to phase 7 again by late January (ideally sooner but I have to be realistic here); phase 7-8 between late Jan and mid-Feb leads to some of the best composites (but again, not La Nina adjusted here...)

 

Generally though, Jan 2018 is looking 'mixed' with variation between more and less interesting conditions - unless, that is, we see some decent disruption of the polar vortex, which remains a possibility regardless of model fluctuations away from it at times recently.

Curiously, while GFS has the 10 hPa level becoming pretty strong for a time and then weakening a bit, the 1 hPa is shown to weaken slowly but surely throughout the 16 day period. 

The result is, if nothing else, an interesting shape to the temperatures .