Winter Model Discussion 18Z 13/1/13 onwards.

[Kentish Snowman in Yorks]

Jet stream just will not play ball for us. At this stage I can't see that changing I think we have a period of zonality well and truly on the cards here. I think we can be fairly confident even at this stage of that, I say fairly as obviously we do not know, BUT I think GFS and its ens have shown a fairly consistent output for 4-5 runs now.

GFS overblowing Atlantic lows again though, I'd wager by the time it gets here its at least 20mb lower pressure, although I suppose its being fuelled by that segment of vortex and the jet.

It depends on your definition of zonality I suppose. I have not seen one low pressure move East of the UK and attack mainland Europe / Scandanavia before T144 on any output for ages now, and after that is very much FI in my opinion.

[Djdazzle]

Surely with all those blues the air will be bitter cold ??

Not as simple as that! Blue colours do not necessarily translate into surface cold.

[nick sussex]

Interesting fax chart for T96hrs:

The high might verify there but I'd urge people to give the detal to the west a wide berth re the snow boundary.

This is likely to be a T24hrs set up in terms of whose likely to get snow off that first shortwave.

One things for sure its going to feel bitterly cold in that ese flow.

Edited January 14, 2013 by nick sussex

[Harsh Climate]

GFS has completly lost the plot for me, look how deep that low is to the south west of greenland, crazy!

[bluearmy]

Surely with all those blues the air will be bitter cold ??

it was before it spent a few days over the warm atlantic. temps at the surface are around 8c under that deep low. at 850hpa, around freezing.

the T96 FAX looks raw UKMO. the T120 will be interesting as the trend from the 12z's is definitely a temporary incursion into the southern half of the uk T144 - T192 period. lets see what the 00z bring.

[Skyraker]

Surely with all those blues the air will be bitter cold ??

Those are 500hpa heights, not temperatures.

Most make this mistake when first hitting the model output threads so it's normal....

[snowice]

Worth noting the GFS Had the Atlantic onslaught as early as this wednesday on its T144 Charts last week, then back to Thursday, then Friday, now Saturday.

Wonder if tomorrows runs will surprise surprise be Sunday at T120!

It did the same in 2009\2010 winter!

[Jax]

Surely with all those blues the air will be bitter cold ??

That is not a temp chart, it is a thickness chart, and the SLP lines show it dragging in air from the SW ish area.

[Weathizard]

That is not zonality, W.

It is a large Atlantic trough that started life as the remnants of the Candian polar vortex.

Ah thanks for clarifying this I haven't seen these sorts of charts in my 3-4 years model watching, I always assumed W-E flow is a zonal flow, apologies to all as I've well and truly been put in my place!

Could the GFS really flip from such a bullish output? I mean the models were randomly flipping run by run last week but the GFS and more crucially its ENS are not offering much hope for the cold spell continuing, although as has just been said, it does keep being put back which can only be a good sign.

Edited January 14, 2013 by Weathizard

[BorrisB77]

I know this is not totally model related so sorry mods ( delete if applicable) but does anyone know where Mr Murr has gone? Really appreciate his comments on the models as I do the rest of you.. Keep up the good work!!

[Bristawl Si]

Interesting fax chart for T96hrs:

The high might verify there but I'd urge people to give the detal to the west a wide berth re the snow boundary.

This is likely to be a T24hrs set up in terms of whose likely to get snow off that first shortwave.

One things for sure its going to feel bitterly cold in that ese flow.

That ties in with what Ian F posted in our regional thread earlier tonite.

Shift South - by friday must be a chance it'll be N France

Edited January 14, 2013 by Bristle boy

[-uksnow-]

I know this is not totally model related so sorry mods ( delete if applicable) but does anyone know where Mr Murr has gone? Really appreciate his comments on the models as I do the rest of you.. Keep up the good work!!

Sorry mods - he appears to have joined our comrades over at TWO.

[BLAST FROM THE PAST]

Digging further south again and getting more held up. Jet IS NOT POWERING THROUGH

BFTP

[Djdazzle]

Ah thanks for clarifying this I haven't seen these sorts of charts in my 3-4 years model watching, I always assumed W-E flow is a zonal flow, apologies to all as I've well and truly been put in my place!

Could the GFS really flip from such a bullish output? I mean the models were randomly flipping run by run last week but the GFS and more crucially its ENS are not offering much hope for the cold spell continuing, although as has just been said, it does keep being put back which can only be a good sign.

The GFS was bullish last week about driving the shortwave to the north over a good few runs, and turned out to be wrong. So yes, it has happened!

[weatherguy]

Ah thanks for clarifying this I haven't seen these sorts of charts in my 3-4 years model watching, I always assumed W-E flow is a zonal flow, apologies to all as I've well and truly been put in my place!

Could the GFS really flip from such a bullish output? I mean the models were randomly flipping run by run last week but the GFS and more crucially its ENS are not offering much hope for the cold spell continuing, although as has just been said, it does keep being put back which can only be a good sign.

It's not that far off from a great run, if that low undercuts just a tad further south then we get raging blizzards. Most likely is the low is being modelled too strong (typical from the GFS), and a weaker low would undercut more successfully. Regardless, it's moved further towards the UKMO (and ECM) solution today so I wouldn't say its been bullish.

Furthermore, mean zonal winds are very weak right now so our block is in a stronger position than it would be in "normal" circumstances.

Edited January 14, 2013 by weatherguy

[ChartViewer]

Cold fighting back CMA216

[nick sussex]

That ties in with what Ian F posted in our regional thread earlier tonite.

It really is an impossible forecast at this range because there are so many variables at play.

Depending on the strength of the block the snow boundary is likely to change between runs and relatively small distances can mean the difference between snow/rain or being dry.

[pages]

Excellent re load potential here CMA192

BYE BYE Jet

I actually think the CMA is the mostly likely route forward, the trend of the last few days has been to slowly strengthen heights to the north. Seen similar to t192 on a few ensembles. In 2 hours lol, I fully expect the t240 frame show Greenland heights linked with arctic heights and a lobe of the vortex heading through scandie at us with freezing north easterlies.

Edited January 14, 2013 by pages

[kate1]

I know this is not totally model related so sorry mods ( delete if applicable) but does anyone know where Mr Murr has gone? Really appreciate his comments on the models as I do the rest of you.. Keep up the good work!!

He's posting mostly in the London/SE regional thread atm.

[Carlrg]

Just seen BBC forecast and the Scandi high was definitely building at the end of the run!

[Cloud 10]

Fax chart at 120 hrs keeps things very cold.

[stratty]

That ties in with what Ian F posted in our regional thread earlier tonite.

Shift South - by friday must be a chance it'll be N France

BBC already mentioning that the weather could turn interesting (not that it hasn't been today already!!!) at the end of the week. (News 24 9.55pm) Showing a stalled front across the west........where exactly will it stall is the question!

[Liam J]

Really bonkers charts, look at the uppers flooding across the Atlantic!

[Jax]

No charts (Sorry), but short term is looking cold overall, but as many have said the tail end of the week is looking "combative" regards the East West influence, anyone know the outcome? doubt it at even this short time frame.

Going forward my gut hunch is the block will hold for the north and east, but the south and west may not, but hey the potential on that forecast front Friday does hold some potential.

Guess we will all have to wait till we get model agreement and some closer model data.

good fun what!

[Snowly does it]

Lol GFS low res goes for one of its snowy westerlies fun runs