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

[Grimsby Snow Lover]

An interesting chart at 240 hours on the ECM. Still way earlier than I am expecting any significant cold to appear in the output, but interesting nonetheless. The vortex over Western Greenland and Eastern Canada is strong here, which is why a warming would be welcome. I'd be interested to know what all of you make of this chart

This looks very similar to how the 6Z GFS run finished this morning

http://cdn.nwstatic.co.uk/gfsimages/gfs.20131229/06/384/h500slp.png

[Mucka]

An interesting chart at 240 hours on the ECM. Still way earlier than I am expecting any significant cold to appear in the output, but interesting nonetheless. The vortex over Western Greenland and Eastern Canada is strong here, which is why a warming would be welcome. I'd be interested to know what all of you make of this chart

 

 

Without over analysing a day 10 chart, there is clear potential for an Easterly to set up later so I guess it at least ends the evening runs on a positive.

[Gibby]

Good evening. Here is my latest analysis of the 12 noon outputs from the NWP for today Sunday December 29th 2013.

 

All models show an active frontal system crossing the UK overnight with rain and strong winds already over the far West moving across all areas by midnight or soon after. Tomorrow will see the front clear SE England through the day followed by less windy and quite bright conditions with just a few showers over hills and coasts in the West. Then on Tuesday another disturbance will run across from the South-West with further heavy rain and strong winds followed by showers with New Years Day following a similar pattern to that of New Years Eve. On Thursday rather colder and still breezy conditions will be present over all areas with a mix of sunshine and showers, heavy and thundery in places and falling as snow on hills in the North.

 

GFS then leads us into next weekend with gales and heavy rain followed by colder weather with sunshine and showers in a blustery NW flow before the whole pattern resets early next week with further strong winds and rain for all. For a time the heaviest rain will transfer North to affect Scotland and Northern England with SW areas becoming drier though windy for a day or two before very unsettled weather returns to all areas before the end of the run.

 

UKMO tonight closes it's run next Saturday with a very disturbed pattern across the British Isles with deep depressions crossing over and close to the North ensuring next weekend stays wet and occasionally windy and rather cold in the North with snow showers on the hills.

 

GEM remains resolutely unsettled at the latter stages of it's run with Low pressure persistent to the North and a strong Westerly wind carrying rain and showers across all areas with snow on Northern hills at times and temperatures generally close to average.

 

NAVGEM tonight is also very disturbed next weekend with Low pressure clearing away East only to make way for another deep one close to the NW with strong and blustery winds coupled with periods of rain and showers from fast moving troughs the ongoing outcome.

 

ECM is broadly similar with a window of fine conditions next Sunday not unlike today's as a brief ridge passes over but as always of late it doesn't last and by the start of the new week very deep Low pressure out to the NW sends strong winds and rain NE across all areas followed by windy and showery conditions. At the end of the run a window of potentially much colder and drier period looks possible as the Low pressure slips SE over the UK followed by a building ridge of High pressure with NE winds for a time with wintry showers for all areas and frost at night.

 

The GFS Ensembles still show no definitive trend towards anything other than what we have received over the last couple of weeks with powerful depressions keeping the mobile and sometimes stormy weather pattern going with just short gasps of polar maritime air on the rear end of exiting depressions before the next one comes along. The net result is for the mean average for the set staying close to the long term mean.

 

The Jet Stream keeps pushing relentlessly strong across the Atlantic towards Northern France or the UK throughout the period on show tonight.

 

In Summary tonight the pattern remains very unsettled and potentially stormy at times. There will be copious amounts of rain for all areas over the next few weeks with no area immune. With only short drier and somewhat colder periods on offer under transient ridges, and with ECM possibly offering up something more sustained for a time in 10 days or so it's not all gloom and doom. However, there is a lot of water to pass under the bridge before any such changes could occur and we must continue to wait for more definitive and cross model agreement on any changes shown in the longer term before we can begin to believe that a change of pattern is about to happen soon.

 

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

 

 

 

http://www.meteociel.fr/modeles/gefs_cartes.php?code=16&ech=192&carte=&mode=0

 

 

 

 

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well  all i can see to Jan 14  is  constant  storms !  with  a bit  of snow chucked  in the  mix 

Edited December 29, 2013 by tinybill

[nick sussex]

Bar a bit of window dressing from the ECM at T240hrs the models generally all have the same theme, the PV drains eastwards, a small amount of trough disruption near the UK, next low moves in and then a question mark as to what happens with the displaced Azores high.

 

As for the ECM at T240hrs  a small tease but theres not enough of a ridge to the north and the PV is still too far east into Greenland and given the recent performance of the ECM  at the later timeframes its hard to have a lot of faith in any of its operationals at that range.

 

Going forward then I think the Azores high will either make or break a chance for cold within ten days, that needs to ridge north and delay the train of lows coming out of the ne USA, with the Arctic high still lurking then that might leave a window of opportunity.

[NorthernRab]

Snow doesn't settle on flooded ground sorry. I love snow but I would gladly settle for a spell of dry weather when this rubbish spell finally ends.

 

It most certainly does - I think you need to visit the Scottish Highlands or Norway! 

[lassie23]

Tomorrow is looking awful, possible sting jet development.

[bobbydog]

Without over analysing a day 10 chart, there is clear potential for an Easterly to set up later so I guess it at least ends the evening runs on a positive.

 

i agree. as many people have said (repeatedly...) the models are not showing heavy snow and deep cold within their forecast timeframes. what they are showing, is a gradual (albeit in a 'zonal' way) slide into more wintry weather, with a marked potential for a change to much colder conditions.

yes the jet is strong for now, but some runs have shown this as a potential (note the word 'potential' again) way to blast troughing into southern europe allowing that "pesky" azores high to ridge northwards.

 

i've said it before but a strong PV and high pressure seemingly in the 'wrong' place have then led to some of our most memorable winters.

add to that a possible SSW on the cards then we could potentially see some dramatic changes to come.

 

time will tell......

[Robbie Garrett]

Is it possible for the jetstream to maintain it's momentum and head south or in it's current position it would be strongest?  Just wonder if it could provide some undercutting lows rolling into an easterly like Feb 2009.

[Frosty.]

I think T+240 hours could be a very interesting timeframe as there are significantly more cold possibilities around that time and beyond with the jet digging well south and a higher risk of colder air across the uk with wintry ppn, ice and frosts. I like the look of the last frame of the Ecm 12z op run and some of the GEFS 12z perturbations including the control run look tasty..from a cold perspective. I will never hide my bias, it's supposed to be winter and I want snow dammit!

[nick sussex]

Hold the front page! after days of ECM operationals not being supported by the mean in the later timeframes tonight we finally see a change!

 

The mean is close to the operational and  if you're hoping for a change then in a nutshell you need to see ridging edge sw'wards from Greenland to help disrupt some energy away from the PV.

 

 

You need a gap there to allow the ridge to extend sw, no phasing of energies between the PV and troughing over the UK.

 

Looking at the extended ECM De Bilt ensembles theres a huge spread in terms of wind directions from the 8th January, temperature wise the trend is down past that point, with my favourite the rogue max temp one for De Bilt of -5 and dew point -20!

 

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

 

We've seen this potential before which doesn't manage to see the light of day, given some improvements in the strat and the expected Arctic high still lurking then we can just hope that the cards fall more favourably this time.

Edited December 29, 2013 by nick sussex

[bluearmy]

yep - that mean atlantic ridge is garnering wide support. no complex comments from me on the 12z extended, other than to say that the cooling off as we end the first week of jan (there are also some cooler days before then) currently looks to be unlikely to go onto become a cold period. the ens are twitching as i wondered if they might. the mean may well be entering a period where it will become quite useless as we see very different clusters generating an average mean. however, the anomolys are indicating that the mobile w-e set up is likely to renew once/if this atlantic ridge has thrown itself northeast. there are possibilities of something to tickle the coldies on a temporary basis at this juncture but it does look like the atlantic will then power through and flatten the pattern once more.  note that this is based on the past couple of runs and we should be a little circumspect until we see a trend taking over more convincingly,  after all, the extended ens were up until recently, solid on the trough digging into europe much more aggressively than now seems likely to verify.

[johnholmes]

this tends to go against what ba has just posted and it is not a one off by the way, see my pdf, it is very far from a 'done thing' but if you are a cold fan then it seems to me to be the strongest hint in the almost 4 weeks so far of meteorological winter.

 

to follow on from my earlier post in pdf format, below is the link for the 8-14 and its 6-10 version.

Of note perhaps, is the slight rise in heights in the Atlantic over the last issue, coupled with the issues I commented on earlier..

http://www.cpc.ncep....14day/500mb.php

 

IF the 3 sequences continue as they have over the past 3 runs or so AND that is converted into actual 500mb charts then there are reasonable signals to support the idea of colder weather being on its way-I did say IF AND!

[nick sussex]

yep - that mean atlantic ridge is garnering wide support. no complex comments from me on the 12z extended, other than to say that the cooling off as we end the first week of jan (there are also some cooler days before then) currently looks to be unlikely to go onto become a cold period. the ens are twitching as i wondered if they might. the mean may well be entering a period where it will become quite useless as we see very different clusters generating an average mean. however, the anomolys are indicating that the mobile w-e set up is likely to renew once/if this atlantic ridge has thrown itself northeast. there are possibilities of something to tickle the coldies on a temporary basis at this juncture but it does look like the atlantic will then power through and flatten the pattern once more.  note that this is based on the past couple of runs and we should be a little circumspect until we see a trend taking over more convincingly,  after all, the extended ens were up until recently, solid on the trough digging into europe much more aggressively than now seems likely to verify.

I think most coldies at this point would take a tickle!!! lol given the garbage that's had to be endured so far this winter. In terms of those extended ensembles for arguments sake lets says the T240hrs verifies with some trough disruption and the PV held further back then I think all bets would be off then, of course that's a big IF given how difficult its seemed to get a clearance of energy from Greenland.

[lorenzo]

That's a monster cold run within that set Nick, worth posting image.

[nick sussex]

That's a monster cold run within that set Nick, worth posting image.

Capture.PNG

 

That's very funny! it's  a shame that the ECM pulled the postage stamps,we could have seen the early transition of the Murr Special!

[Cloud 10]

Big difference between the ECM ensemble mean and the NAEFS at 240 hrs regarding any

Atlantic ridge.

 

ECM..  NAEFS..

 

 

Lets hope the ECM ensembles aren't suffering from a case over amplification 

 

 

love "the Murr run" btw. 

[Snowman.]

Hmm 18z is gearing up something for us..

 

[TSNWK]

Polar heights not nearly as good on the 18z. Another storm incoming at 168.

[fergieweather]

That's very funny! it's  a shame that the ECM pulled the postage stamps,we could have seen the early transition of the Murr Special!

some colder (mostly cyclonic & some deeply so) solutions in there out through T+240 to T+360 but also a raft of possible synoptic types, as expected.

[Tim Bland]

Cold zonal is over used in here but the 18z really does show this http://www.meteociel.fr/modeles/gfse_cartes.php?ech=288&code=0&mode=0 that would be very snowy especialy for higher ground!

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=300&code=0&mode=1

Edited December 29, 2013 by Tim Bland

[TSNWK]

18z is poor for those at risk of flooding. No real sustained cold, just a slightly more chilly version of what we endured back end of December,with occasional breaks as the Azores high ridges over us. Poor run for coldies and more concerning are the amounts of rain. Night.

Edited December 29, 2013 by TSNWK

[I remember Atlantic 252]

Snowfest FI for Wales and Ireland though, hope start of a trend, as for my location it will be cold dry days, Ive got at least 8 days of constant rain coming up

[Tim Bland]

18z is poor for those at risk of flooding. No real sustained cold, just a slightly more chilly version of what we endured back end of December.

Have you seen the uppers that are associated with the low pressure?! http://www.meteociel.fr/modeles/gfse_cartes.php?ech=372&code=0&mode=1http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=336&mode=1 Edited December 29, 2013 by Tim Bland

[TSNWK]

Have you seen the uppers that are associated with the low pressure?! http://www.meteociel.fr/modeles/gfse_cartes.php?ech=372&code=0&mode=1http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=336&mode=1

Colder rain..