Model Output Discussion - Christmas and New Year

[tight isobar]

Ecm raw.. well within it’s supporting . Other operationals also in revert-and sync...   the 500s will be reflective!..  stop wasting ya panic pills

[Scott Ingham]

5 minutes ago, Kasim Awan said:

Euro 4 now significantly further east. ECM has hinted at this so jury's still out though a central track is gaining credibility now. Any thoughts?

Not my area of expertise.

Id suggest the pennines and lancashire to get a pasting, east of the pinnines and the midlands a dusting 1-2 cms.

Id trust your judgement more im more of al long range forecaster

[chicken soup]

53 minutes ago, Kasim Awan said:

The mean wind speed tomorrow is looking to be South of West which will funnel most streamers into Burnley, Forest of Bowland, Southern Dales up to Hawes. 4-8cm here up to or over 20cm possible above 250mts no exaggeration

If it going to Burnley then surely it will hit Blackburn aswell.. I will be devastated beyond compare if Burnley gets it and I dont

[Mike Poole]

21 minutes ago, Scott Ingham said:

Look at the pattern over the states on ecm 240 Mike

First signs there. The high above the UK will retrogress opening up another reload of cold from the North

Yes, it will, Scott, I’ve said before that i think we are locked into a rinse and repeat phase of Atlantic amplification until the SSW, and the trop response, have happened, typical of a meridional pattern that is still moving east, rather than a fully blocked static pattern.  What happens after the SSW, uncertain, but those model runs that do the splits in the strat, do them in favourable places as far as I can see...

Edited December 26, 2020 by Mike Poole

[Anthony Burden]

One bitterly cold ECM with north easterly winds and high pressure dominate.

After storm Bella decides to move off after depositing snow over good parts of the UK

over several days ECM very keen on high pressure with the correct orientation to 

drive some bitterly cold north easterlies winds,great watching full stop.

 

[tight isobar]

As regards Monday featured.. those ramping the precipitation charts.. will be disappointed “imo “ exit point remains.. as does any notable-insert.. @diaginal track.. @exit south east coast .. and where the roll/pivot/extreme will be likely.. within a radius!      Ecm a very good 0/-240..   in general conscience!! .. winters about to ring the doorbell!!!!!

Edited December 26, 2020 by tight isobar

[Scott Ingham]

I for one hope the latest euro4 is correct as it gives south yorkshire a fair few cms!

[Cuban Zebra]

33 minutes ago, snow mad said:

Surely be convection off that for east anglia and kent 

Sweet spot for convection is from The Wash North, you get a long fetch across the Baltic Sea, then the North Sea! Yorkshire normally is in the firing line!!!

[radiohead]

43 minutes ago, Tim Bland said:

How is it still showing rain

Because it's showing the dew point at that time between +2 and +3. Needs to be 0 or below for precipitation to fall as snow.

[Biggin]

42 minutes ago, snow mad said:

Surely be convection off that for east anglia and kent 

I make you right. Thames Streamer, Wash Streamer

[Scott Ingham]

21 minutes ago, Mike Poole said:

Yes, it will, Scott, I’ve said before that i think we are locked into a rinse and repeat phase of Atlantic amplification until the SSW, and the trop response, have happened, typical of a meridional pattern that is still moving east, rather than a fully blocked static pattern.  What happens after the SSW, uncertain, but those model runs that do the splits in the strat, do them in favourable places as far as I can see...

I fully agree. People shouldnt judge this as historic because of no -10 uppers. 

It should be judged (it needs to happen its only forecast) be judged on longevity in the heart of winter.

If we remain belowe average through january ans its not classed as historic then god knows what people think is historic!! 

Next ice age i guess!

[Djdazzle]

2 minutes ago, radiohead said:

Because it's showing the dew point at that time between +2 and +3. Needs to be 0 or below for precipitation to fall as snow.

I’d be surprised if the dew point was that high. Anyway, it’s all academic at that range.

[Tim Bland]

Just now, Djdazzle said:

I’d be surprised if the dew point was that high. Anyway, it’s all academic at that range.

Agreed. Would be very unlucky to have an easterly. Uppers of -8c and DP of. 2c in early Jan ! 

[Uncertainty]

My pseudonym was never more appropriate...

JMA 192

GFS parallel 

GEFS mean at 192

Regardless of the disruption type, huge differences in the level of warming at day 8. Many of the finest on Twitter are favouring an initial displacement so it remains a watching brief. Hopefully some clarity on this asap.

 

Down below the shenanigans, EC continuing the trend I have been seeing over the last few days, heights transferring towards the E/NE over the top of the U.K, a ‘toppler’ @IDO yes, but a very nice one. The full GH by end of December was never consistently progged by the models, but significant Atlantic height rises certainly were and these look like verifying nicely. 
 

Back to the present and the pivoting band of sleet and snow tomorrow is predictably proving unpredictable. There are two primary uncertainties:

1) The initial track of the surface low overnight Sunday as it tracks SSEward towards the Irish Sea. The Euro 4 and UKV are taking it through the Eastern Irish Sea, with the snow band through NW England

Alternatively, the Arpege takes the low through Northern Ireland southwards, with the snow avoiding mainland England altogether 

Other models are somewhere between the two tracks. The MO warning update tomorrow morning will be revealing.

2) The low then continues SE, perhaps pivoting as it does so. The Euro 4 brings the SE into play, as does the GEM

Many other models have the track further west, the SW could be in the firing line here

Added to this is the marginality debate that has been one of the many ‘themes’ of this thread over the last few weeks (and indeed, ‘‘twas always thus”).

Either way, it’s nice to be viewing Hires models outside of the summer thunderstorm window. The only reason I’m used to viewing them in Winter is for rainfall accumulation forecasts, a lonely and miserable activity that sadly is necessity in a canonical Cumbrian winter.
 

But this is proving so far not to be a canonical winter at all. Which is brilliant.

So here’s to the, ahem, uncertainty!

[tight isobar]

Why the hell is there rucking about dews /humidity/evap.. they are overheads.. look at them as they unfold- and as any frontal is inbound-immediate.. that’s exactly why the word “nowcast”... is worthy...  I’m going to lay down

Use these via meteocial-observation tools..

Edited December 26, 2020 by tight isobar

[The Enforcer]

4 minutes ago, radiohead said:

Because it's showing the dew point at that time between +2 and +3. Needs to be 0 or below for precipitation to fall as snow.

Typical of an Easterly to bring a mild sector all the way from Siberia, which of course still delivers snow on the French coast.

[Hotspur62]

An interesting last few days modern watching in between the festivities.From what I am taking from the models is that from tomorrow we are in for a cold week with favoured spots with elevation of 150m in NW Britain predominantly getting a nice covering I would think.There is also the uncertainty of Monday/Tuesday developments that maybe resolved by this time tomorrow which would place other areas for potential snow cover.Then for the rest of the week it looks colder than average but no clear signal for snowfall for the UK.At the moment I would favour drier conditions but as is the norm with the UK and potential snow things don’t normally pop up till the last minute.This I feel is causing frustration in this forum(understandably) as the Synoptics look conducive to snow but it may not happen.

I feel we must look at the LONGER TERM pattern which the experienced and most knowledgeable members are advising us to do.If we get snow this week see it as a bonus but I feel January 2021could be one we look back with fond memories when we look back at the winter as a whole

Stay safe and those that are lucky enough to get snow please send the pictures through in the Regionals

[Djdazzle]

1 minute ago, Scott Ingham said:

I fully agree. People shouldnt judge this as historic because of no -10 uppers. 

It should be judged (it needs to happen its only forecast) be judged on longevity in the heart of winter.

If we remain belowe average through january ans its not classed as historic then god knows what people think is historic!! 

Next ice age i guess!

The historic mantle will only be awarded if there is lots of snow and / or sub zero daytime maxima, as that’s what people remember.

1947, 1963, 1981/1982, 1987, 1991, 2010 and 2018 are probably in that category, so the bar is quite high!

 

[Catacol]

47 minutes ago, syed2878 said:

 yet with this set up not everywhere will get snow and that also confirm by today’s warning from the Met I cannot see any significant snow for low-lying Britain in the next 10 days yes the SSW might help then again it might not there is no guarantee that it would bring called to our shores. in fact the SSW mate shuffle the cards and take us out of the pattern we are in at this moment.

What pattern would you prefer us to be in? Currently we have a northerly likely to back easterly at times. Slider potential still there. What would you like to see a shuffle bring?

[iand61]

1 hour ago, Kasim Awan said:

The mean wind speed tomorrow is looking to be South of West which will funnel most streamers into Burnley, Forest of Bowland, Southern Dales up to Hawes. 4-8cm here up to or over 20cm possible above 250mts no exaggeration

Yeah for here showers from a westerly or wsw seems to give the largest snowfall amounts.

we got around 30cm in an afternoon from a similar set up a few years ago.

[I remember Atlantic 252]

happened here too, wet even slight thaw of existing snaw

[northwestsnow]

Anyone lucky enough to have snow-cover would be recording some very low temps on  EC this evening.

Charts I could only dream of over recent years...( March 2018 aside).

 

 

[Weathizard]

Beautiful ECM mean, Atlantic absolutely dead and buried without the SSW and other factors about to come into play 

[Scott Ingham]

2 minutes ago, Djdazzle said:

The historic mantle will only be awarded if there is lots of snow and / or sub zero daytime maxima, as that’s what people remember.

1947, 1963, 1981/1982, 1987, 1991, 2010 and 2018 are probably in that category, so the bar is quite high!

 

But snow cant be modelled until within 48 hours as the latest shift north in snow on the higher res models show.

To say no snow based on modeos 144+ is futile 

If its cold enough snow will always pop up in the way of troughs etc.

Synoptics show a possibility of cold all the way through January intensifying week on week.

Snow comes hand in hand

December 2010 looked dry in fact it showed 8 days with no snow on the snow rows 120 hours + so historic us very much a possibility 

[Mike Poole]

ECM mean and spread, there is a lot of uncertainty and it affects us (highlighted the tip of Greenland), T240:

Does the mean look more uncertain or worse than the 0z, here’s the 0z:

The medium term evolution is uncertain at the moment, as far as this model is concerned, I think continued high latitude blocking of some sort will win out, before the SSW starts to affect things.  Interesting times...