Model Output Discussion 17th Dec.2013-12z onwards.

[Downpour]

I know people have been inundated with my ratings over recent weeks! We've had horror, sledge, cold ratings. In the New Year I will be unveiling the following: Can I Take A Day Off Work Due To Snow Without Getting My P45 Rating The PV Get Lost Rating Will COBRA meet rating Will London Buses Stop Running Rating Will Boris Johnson Sort His Hair Out Rating Apologies to those who are rated out ! Overall the output is neither a mild horror show or particularly wintry, hopefully we can see changes in the New Year and won't have to be obsessing over the marginality of any snow, SAY NO TO SLUSH! We want  HLB!

Quite right Nick. I'd struggle to even celebrate a slush fest on Christmas Day. Meanwhile, for those that like puddles, may I recommend Epping Forest - absolutely tore it up on the bike this afternoon - there is a particular knack to riding down a two foot drop into a stream and back up again which I am getting close to perfecting. The models suggest I will have plenty more practice, but January might see a change.

[fergieweather]

Monday the next looming saga (frontal waves Sat aside). EC and MOGREPS postage stamps from 12z members today agree on more southerly bias to deep development up NW. GFS looks on a limb way further N. Modified UKMO-GM something of a replica of today's conditions, but some of the EC/MOGREPS members more troubling. Definitely the next focus of broadscale interest IMO...

Edited December 18, 2013 by fergieweather

[Joe Levy]

Monday the next looming saga (frontal waves Sat aside). EC and MOGREPS postage stamps from 12z members today agree on more southerly bias to deep development up NW. GFS looks on a limb way further N. Modified UKMO-GM something of a replica of today's conditions, but some of the EC/MOGREPS members more troubling. Definitely the next focus of broadscale interest IMO...

What sort of features should we look out for in future output for this particular time period? Is it only strong winds that we should be concerned with, or are there other potentially disruptive elements as well?

Edited December 19, 2013 by Joe Levy

[fergieweather]

What sort of features should we look out for in future output for this particular time period? Is it only strong winds that we should be concerned with, or are there other potentially disruptive elements as well?

Rainfall totals are increasingly a concern. Especially in catchments to W where they're already struggling.EDIT Almost all UK snow lying by Sat expected to melt that period of weekend, with exception of highest Scottish peaks. Thus exacerbating flood issues. Edited December 19, 2013 by fergieweather

[ARNOTT ad]

Rainfall totals are increasingly a concern. Especially in catchments to W where they're already struggling.EDIT Almost all UK snow lying by Sat expected to melt that period of weekend, with exception of highest Scottish peaks. Thus exacerbating flood issues.

All uk snow meaning -only Western Scotland and localised Northern Ireland.. Not much there to add to potential flooding us there... Send the snow here to West Yorkshire pleeeaaasssseeee

[Cecil Hogmanay Melchett]

Lovely looking GFS00Z run with plenty of polar maritime (cold zonality) on offer.

Im beginning to think there could be some wintry suprises next week.#

[dallas]

The PV getting shunted away from its greenland anchor, and the jet stream tracking further South.

All later in the run but nice to see.

[shaky]

Ukmo 00z not bad either. Hoping for a good ecm!!

[TSNWK]

00z gfs rasied an eyebrow

From Christmas Day part of the vortex drops over the UK and then bobs around in our vicinity, Boxing Day onwards there are heights of circa 1025 Over Greenland (although I think it is a surface high as is blue, but its there for the rest of the run) polar vortex also starts spitting apart from Christmas Day and at the end looks rather tame and split..

Looked a cold run to me, there must be some surprises in store for the north at the very least.

Edited December 19, 2013 by TSNWK

[Mucka]

Very interesting developments this morning with the jet digging South and height rises to the NE on both GEM and GFS 00z output in the run up to the New Year, something that has been hinted at within the ensembles and appeared on GEM before but it is nice to see two Operational's come up with this idea on the same runs.

 

 

 

Obviously much better cold prospects from there.

 

Unfortunately ECM doesn't repeat the dose, is shallower and moves all the energy NE instead of SE after the mid term

 

So two excellent runs and one poor from the main models regarding a pattern change, let's hope ECM ensembles are more supportive of trough digging  further South.

Edited December 19, 2013 by Mucka

[That ECM]

Very interesting developments this morning with the jet digging South and height rises to the NE on both GEM and GFS 00z output in the run up to the New Year, something that has been hinted at within the ensembles and appeared on GEM before but it is nice to see two Operational's come up with this idea on the same runs.

 

 

 

Obviously much better cold prospects from there.

 

Unfortunately ECM doesn't repeat the dose, is shallower and moves all the energy NE instead of SE after the mid term

 

So two excellent runs and one poor from the main models regarding a pattern change, let's hope ECM ensembles are more supportive of trough digging  further South.

UKMO to my mind is more like the GFS than the ECM but it could be my rose tinted glasses. The lack of agreement at T 144 means we will just have to watch with interest.

[Cecil Hogmanay Melchett]

Well after being very excited about gfs0z ecm brings me tumbling back to earth with a very underwhelming op run.

 

UKMO i feel bears more resemblance to gfs than ecm so hopefully ecm is having another 'turn',if im being honest i have not been overly impressed with ecm this winter so far so lets hope its gone off on one so to speak.

[Nick F]

Yep, some weak height rises in the Greenland area on the 00z GFS op in FI, suggesting a fragmenting of the PV. However, given it's modelled so far ahead, not much support from GEFS and the ECMWF remains bullish with keeping a rounded PV to the N/NW, can't really have much faith in it yet.

In the near time, E4 and NAE still signalling snow to lower levels across Wales, W Mids, NW England early evening, as a trough moves in from the west, perhaps snow to lower levels further east across E Mids to Lincs/Yorks after. E4 slowed the trough somewhat to be more in line with GFS and NAE.

Slow-moving frontal wave across south on Sat, concerning regarding flooding. Then some uncertainties over timing, track, number of more potentially menacing deep lows early to mid next week. gFS has a number of small but intense lows dumbelling around vortex towards Iceland, whilst ECM keeps it simple.

Edited December 19, 2013 by Nick F

[Summer Sun]

Better from ECM again this morning once again its showing these very deep lows coming to an end from around the 28th

 

 

For the Christmas period we a deep low passing NW of Scotland on Christmas eve and Christmas day before the winds ease on Boxing day

 

Edited December 19, 2013 by Summer Sun

[IDO]

Good support for a LP system to hit the UK around Christmas Eve to Boxing Day, timing and strength still to be firmed up on (London):

 

 

The trend that I spotted compared to yesterday's 18z is for pressure to build after Boxing Day; yesterday: 18z: 

 

Looking at the GEFS stamps, solid support for the AH to try to move NE (T240): http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

 

The 0z op looks to have nominal support (maybe two members) for its FI troughing. The ThetaE graph shows most members maintaining a sine wave plot in FI whilst the op has little support in keeping the ThetaE temp more constantly low: 

 

 

The GFS op trough is a rather slack feature and although the GEM is similar, though a bit more active, more support is needed before we can look forward to a relatively cooler setup from this current unhelpful LW pattern.

[Frosty.]

Fantastic potential from the Gfs 00z op run from a cold perspective compared to the flat Ecm 00z, the gfs shows increasingly wintry synoptics as the jet is pushed much further south than it's usual position and the uk becomes locked into a cold pattern with arctic air mixing with low pressure to bring a much higher risk of sleet and snow through the christmas and new year period, the hills in particular would become very snowy if the jet goes that far south. I like how a strong ridge builds south from iceland / greenland and cuts off the route for atlantic depressions to introduce milder air, instead the lows are diverted further south and brings the classic undercut into play..i'm hoping this is the way forward as it screams wintry potential for late dec / early to mid jan. 

Edited December 19, 2013 by Frosty.

[legritter]

Fantastic potential from the Gfs 00z op run from a cold perspective compared to the flat Ecm 00z, the gfs shows increasingly wintry synoptics as the jet is pushed much further south than it's usual position and the uk becomes locked into a cold pattern with arctic air mixing with low pressure to bring a much higher risk of sleet and snow through the christmas and new year period, the hills in particular would become very snowy if the jet goes that far south. I like how a strong ridge builds south from iceland / greenland and cuts off the route for atlantic depressions to introduce milder air, instead the lows are diverted further south and brings the classic undercut into play..i'm hoping this is the way forward as it screams wintry potential for late dec / early to mid jan. 

Fantastic post FROSTY lets hope your right ,but models i feel this morning on a knife edge ,looking to a better run from ECM this evening last few frames this morning no Christmas chear ,STellas all round gang .

[snowking]

Still a lot of uncertainty regarding the proceedings over the next few days with significant model differences for our locale from as early as t+72, so looking further afield at individual deterministic runs at present may prove fruitless.

 

As such, the latest NAEFS warning system output from MeteoCentre now stretches out to christmas day itself:

 

 

Currently a 50% chance of >2cms of snow across the highlands, so the risk of snow here looks fairly good at this stage. Elsewhere it most likely wont be clear until the other side of the weekend.

 

I should imagine there's a few bookies entering squeaky bum time...

 

SK

[nick sussex]

The ECM operational run is well supported by the mean which is rather disappointing. However looking at the ensemble spreads there is a cluster of solutions that take troughing further se into Europe.

Also some ridging is shown extending sw towards the Svalbard region. At the moment you'd still have to say that the ECM is the likelier solution as that has more ensemble support, its the reverse really for the GFS.

We'll see today whether the GFS continues its trend and gathers more ensemble support, the ECM is very underwhelming from a cold perspective and offers little hope of anything wintry.

Edited December 19, 2013 by nick sussex

[Gibby]

Good morning. Here is the report on the NWP output for today's midnight outputs for today Thursday December 19th 2013.

 

All models show the run up to Christmas as unsettled and potentially quite stormy at times as deep depressions continue to run East over or just to the North of the UK. Spells of heavy rain will be commonplace especially later tomorrow and Saturday in the South. Christmas Eve also looks like it could be very wet and windy too. All other times will see a mix of sunshine and showers with wintry showers over the hills at times as air turns briefly colder under these events.

 

GFS shows Christmas Eve as a very unsettled day with deep Low pressure straddling the UK with each centre providing the risk of prolonged and heavy rain and it looks like it would be cold enough for snow on Northern hills. Christmas Day and boxing Day remain very similar with unstable and sometimes strong Westerly winds providing plenty of opportunity for heavy rain and wintry showers. This weather type continues up to and over the New Year with temperatures near to or a little below average.

 

UKMO shows an intense depression just to the North of Scotland on Christmas Eve with strong Westerly winds and rain clearing to brighter or clearer spells and wintry showers with some snow on Northern hills.

 

GEM maintains deep Low pressure over the UK throughout the Christmas week and in the days thereafter with heavy rain and strong winds never far away and with temperatures borderline for snow on hills at times.

 

NAVGEM looks a lot like UKMO for Christmas Eve with the following two days of Christmas following suit with deep Low pressure over or close to the UK maintaining strong winds and heavy rain for many with some wintry type showers in between.

 

ECM shows very unsettled weather over Christmas with rain at times and snow on the hills though it has removed the damaging winds scenario over Christmas on previous output. Nevertheless there is still plenty of wind and rain shown to wash down the Christmas festivities.

 

The GFS Ensembles maintain a very average setup temperature wise made up of an oscillating sine wave pattern by all members with fast changing air types bringing rain areas across from the West followed by showers, wintry on hills. Christmas itself continues to be modelled as a very wet period especially in the South.

 

The Jet Stream continues to be programmed to be crossing the UK strongly from the West for the next week, slipping South of the UK at times over Christmas. It then resets slightly further North across the UK in the run up to the New Year, still very strong.

 

In Summary there is nothing new to report this morning with all models continuing to predict very volatile conditions with spells of rain and gales alternating with brighter and more showery conditions with some snow on the hills. The risk of severe gales over Christmas remains though the operational runs have backed off a little from this today. For those hoping for a pattern change as we look towards the New Year may find that they may have to wait rather longer from this morning's extended model outputs.

[Summer Sun]

Both the ECM and GFS ensembles support the idea of these deep lows coming to an end at t240

 

GFS

 

 

ECM

 

 

Beyond t240 the GFS ensemble shows little change in the pattern

 

[MP-R]

GFS 00Z certainly more wintry than previous runs. The PV is a lot more fragmented, even more so than it has done across previous runs with something of a cold spell between Christmas and the New Year. Still a lot of SW activity though which is impossible to predict in advance and could mean the difference between something wintry and a return to mild weather. Needless to say, mild days are definitely minimal at the moment: turning milder again tomorrow, possibly very mild for a time on Saturday before cooling down again to nearer average into the new week. 

[carinthian]

Another sunny day here. All 3 models in agreement at 144hrs with the upper trough over the UK and all showing some height rises over the Arctic. Thereafter a big difference between ECM and GFS. The former weakens the jet again into Europe with pressure rising again and the re-positioning of the main PV over Greenland, whereas the GFS pushes ithe jet further south with a resultant drop in pressure over Europe. UKMO probabaly going for middle ground again in the post 144 hr period. Its ECM against GFS again, more light will be shed today. It would appear the GFS model has handled this seasons advanced changes better so far.

C

Edited December 19, 2013 by carinthian

[Ali1977]

Xmas eve snow still showing in the GFS

[BLAST FROM THE PAST]

Another sunny day here. All 3 models in agreement at 144hrs with the upper trough over the UK and all showing some height rises over the Arctic. Thereafter a big difference between ECM and GFS. The former weakens the jet again into Europe with pressure rising again and the re-positioning of the main PV over Greenland, whereas the GFS pushes ithe jet further south with a resultant drop in pressure over Europe. UKMO probabaly going for middle ground again in the post 144 hr period. Its ECM against GFS again, more light will be shed today. It would appear the GFS model has handled this seasons advanced changes better so far.

C

Agreed

I think the ECM is on the wrong chord here.  Indeed I am liking the GFS and the GEM with the situation getting quite complex and colder as go through Christmas and get to New Year.  I'm doing my Monthly LRF today and first half of Jan looks like being a very wintry picture. 

 

BFTP