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Model Output Discussion; into 2015


martthefart

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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

what does the polar vortex dropping south mean please?

Thanks

in simplest possible terms, the purple blobs.

one big purple blob means strong PV = bad for cold in UK

lots of smaller purple blobs means disrupted PV = better for cold in UK.

As it is, its disrupted but at the moment, not ideally placed for us

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Posted
  • Location: Crawley
  • Location: Crawley

in simplest possible terms, the purple blobs.

one big purple blob means strong PV = bad for cold in UK

lots of smaller purple blobs means disrupted PV = better for cold in UK.

As it is, its disrupted but at the moment, not ideally placed for us

so we are on the right lines though (because it is distrupted)?

BTW I see you are in Horsham, very close to where I live. Did it snow at any point last night?

Edited by snowy weather
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Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset

so we are on the right lines though (because it is distrupted)?

 

Right lines but the location continues to be unfavourable for the UK in terms of cold and snow. At that latitude, we would want purples over the UK if not to the east. PM's chart on the previous page would just bring wind and rain and average temperatures to the UK as the flow is from the southwest. 

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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

so we are on the right lines though (because it is distrupted)?

well we are, but there are so many other factors which have to fall into place for the UK to get decent cold. its an important factor though and a good starting point to have a weak PV

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Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

Right lines but the location continues to be unfavourable for the UK in terms of cold and snow. At that latitude, we would want purples over the UK if not to the east. PM's chart on the previous page would just bring wind and rain and average temperatures to the UK as the flow is from the southwest. 

 

My post on the previous page was to explain a better outcome from the chart in question, As it progressed. As heavy snow is shown only a few frames on, Hence my further post explaining the outcome.

Edited by Polar Maritime
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Posted
  • Location: st albans
  • Location: st albans

ECMWF, MOGREPS-15 [and Glosea5] all cover out through same period, incidentally (GFS is not really used as a primary tool to decipher trend period pattern, i.e. beyond D6. Only employed as a broad cross-check of interest, comparative to the first two cited above).

 

ian, dont suppose you could enlighten us as to whether, in the 10/14 day timeframe, the 'secret' models 'put humpty back together again' in the upper strat as per gfs ?

Edited by bluearmy
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Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset

My post on the previous page was to explain a better outcome from the chart in question, As it progressed. As heavy snow is shown only a few frames on, Hence my further post explaining the outcome.

 

Sure. It just happened to illustrate my point too. Not denying that there are some charts of interest beyond that. :)

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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

ECMWF, MOGREPS-15 [and Glosea5] all cover out through same period, incidentally (GFS is not really used as a primary tool to decipher trend period pattern, i.e. beyond D6. Only employed as a broad cross-check of interest, comparative to the first two cited above).

sorry ian, i should have added that i was only referring to the models that us mere mortals have access to

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Posted
  • Location: Wakefield, West Yorkshire
  • Location: Wakefield, West Yorkshire

sorry ian, i should have added that i was only referring to the models that us mere mortals have access to

Ah yes but interesting to note that the MetO don't really use the GFS for trend spotting beyond day 6. That'll do for me when using that model from now - I'm stopping at 144 (or just after) when viewing that model in future.
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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Gfs is pretty good IMO, good at spotting trends from two weeks out, the other higher rated models are also riddled with flaws so I'm not dumping the gfs, despite its eastward bias. As for the outlook, coldies will have further snow opportunities in the weeks ahead I'm happy to say.

Edited by Frosty.
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Posted
  • Location: Broxbourne, Herts
  • Weather Preferences: Snow snow and snow
  • Location: Broxbourne, Herts

so we are on the right lines though (because it is distrupted)?

well we are, but there are so many other factors which have to fall into place for the UK to get decent cold. its an important factor though and a good starting point to have a weak PV

I guess there would be four circles of a Venn Diagram to get the perfect winter incorporating a circle of a disrupted PV, one for a Scandi high, one for a Greenland high and one for low pressure over the Med.....although possibly interaction a couple of others would be needed as well!

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Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL

All I can see in the models at present is a broadly zonal pattern. Yes, this is pulling in colder than average air due to a segment of the PV being pushed to our side of the Northern Hemisphere by the intense Alaskan High.

There is no sign at all of either a sustained Greenland or Scandavian High to herald a more prolonged nationwide deep cold spell.

We are essentially back where we were a month ago with an Atlantic driven pattern, however, with a more Polar Atlantic element the possibility remains for snow.

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Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

Looking at the models and coupling that with effects in the stratosphere, I do feel around next weekend we might get one shot at developing a weak high somewhere to our north (between Iceland and Scandinavia). Hopefully we will start to see trending on this scenario.

Otherwise a mostly dry few days until it turns more unsettled and briefly milder towards the end of the week before colder air spreads south east Friday night to bring a clearer and sunnier weekend. Beyond that, will we develop something colder or something wetter and stormier. At the minute I would keep an open mind.

Taking this chart as a starting point.

ECM1-216.GIF?27-0

We would want some light blues or greens around Iceland which will divert that low further south and possibly allow colder air to flood towards us from the east/north east.

Just speculation of curse but at this present time apart from some rather poky PM bursts then I see no other route to something more favourable for those of the cold and snow disposition.

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Posted
  • Location: Winterbourne, South Glos
  • Location: Winterbourne, South Glos

Agree with Frosty for the 18z and Nicksussex for the earlier 12Z run there are trends showing for opportunities for higher latitude encroachments of higher heights and blocking scenarios accompanied by (and initiated by) deeper digging of the troughs running out of the NE USA and PV down South East of us. Much of it could turn into cold rain and windy weather with PM snowier stuff up north and over the hills but one of these digs SE may well become the trigger to something more exciting. Still interesting times ahead as we move into early Jan.

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I don't know if the Jamstec LRF has been posted in this thread but their latest update is going for a below average Dec-Feb and also a below average for Mar-May. This was the best I could contribute to you guys not the best but a contribution nonetheless.

 

Dec-Feb: http://www.jamstec.go.jp/frcgc/research/d1/iod/2007/forecast/temp2.glob.DJF2015.1dec2014.gif

 

Mar-May: http://www.jamstec.go.jp/frcgc/research/d1/iod/2007/forecast/temp2.glob.MAM2015.1dec2014.gif

Edited by Sean19
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Posted
  • Location: Maltby, Rotherham - 150m ASL
  • Weather Preferences: Snow and Cold! Winter :)
  • Location: Maltby, Rotherham - 150m ASL

Well to say its at T144, there is decent agreement between all models tonight for a cold ~2nd January, or somewhere around that period. UKMO, ECM, both GFS brothers and GEM all have cold uppers again approaching from the west. Could it just be coincidence or have they picked up on a strong signal??

 

Id love two snowy Fridays in a row! :w00t:

 

 

I would love one snowy Friday!

 

I didnt mean to upset anyone with my last comment ( I can see you got 13 likes for your reply) so sorry if it looked that way :)

 

The GFS's keep that signal I mentioned going on the 18z runs too for early Jan...

 

gfs-1-162.png?18gfs-1-162.png?18

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

www.wetterzentrale.de/pics/Recm1921.html

interesting ECM at T192 ... a little low tries to break south, a little ridge to its north, some snow potential on the back of this one maybe? Seems a little odd to be honest but the pattern of ridging to our north continues, something to keep watching.

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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

No real change up to D10 in our sector, we lose the high by D5 and it's cool zonal from there. The main models:

 

post-14819-0-49240800-1419751278_thumb.ppost-14819-0-92612800-1419751278_thumb.ppost-14819-0-50076100-1419752201_thumb.g

 

The usual culprits, ECM over doing the heights, GFS over doing the Atlantic and GEM somewhere in between. Not any of the GEFS support the ECM D9 chart (Atlantic toppler).

 

The general consensus on the GEFS and where GEM is going is that the WAA stops pumping up the Alaskan ridge and the wedge of heights becomes mobile. All happening still on the other side of the hemisphere so at D16 no sign of a MLB or HLB in our sector. The mean is reflective of the synoptics, blocking over the Asia/Pacific so the PV lobe is drawn to our NW:

 

post-14819-0-80271300-1419751528_thumb.p

 

This has been a signal for over 4 runs (06z/12z) so looking like a pattern. Lots going on in the strat so this is not set in stone and it could be ECM is picking up the coupling better or its just up to its old tricks, time will tell.

Edited by i'm dreaming of...
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Posted
  • Location: Greenhithe, N/W Kent (home) City Of London (work)
  • Location: Greenhithe, N/W Kent (home) City Of London (work)

ECM seems to be still on the 12hours, except on wetterzentrale

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