Model output discussion - Closing in on Christmas

[northwestsnow]

2 minutes ago, Snowman. said:

Its likely to be just wet. Ural high stoping any real advances of the lows so they just sit over us and fill.

Likely to be cold, and some white stuff about if you head further north or better elevation. But many in this thread don't live in such places so seeing a T240 chart show large amounts of blocking but sod all real cold doesn't envoke a good response. 

PV is in tatters and we're still struggling to get a half decent cold spell!

The uppers look pretty crap south of Manchester but uppers not the be all here.

I haven't looked at EC surface temps but I bet they will be suppressed...

[daz_4]

14 minutes ago, northwestsnow said:

Crikey I hope jules216 isn't watching EC det roll out ...

Had to open a beer watching that unfold. We are really cursed. This is trending the wrong way and I think it's not that good for UK as well. Where are the times where the LP was centered over Italy and then tracked NE pulling cold air behind it? Horrible horrible run.

[damianslaw]

8 minutes ago, phil nw. said:

I guess we were hoping the ecm wouldn't follow the gfs in showing the pattern too far west. 

It is a really promising nh profile overall so this outcome would be really frustrating for snow lovers. 

There is still time for an adjustment, let's hope it goes a little way east. 

Agree, Phil as per comment a long time for adjustment.. 

[Man With Beard]

Woah woah woah, what's all this "ECM capitulates to the GFS" or "GFS wins" talk? The scenario in question is still 7 days away! It's far too early to cast judgement!!

But I'm still enjoying this evolution. If it lands halfway between the ECM of this morning and tonight, the UK will be in the cold "sweet spot"

[Scott Ingham]

27 minutes ago, I remember Atlantic 252 said:

850's not great on this, bit better than 4th/5th though

Off the back off a few surface cold days from chridtmas eve also. We went from warm to vold reoatively quick at the start of the month. Theres really no basis just yet due to the many variables (because others matter its not just about 850s) for anyone to call rain or snow until 48 hours out ajd we have the likes of the euro4 in range

[Snowman.]

1 minute ago, northwestsnow said:

The uppers look pretty crap south of Manchester but uppers not the be all here.

I haven't looked at EC surface temps but I bet they will be suppressed...

Don't get me wrong it will feel cold and be cold. As always a bit of IMBYism going on here but the past few years have been tough in regards to lost chances and to see the first actual Greenie high possibly become a west based -NAO just hurts a little.

Plus it's 2020 and we all know that this year hasn't been a good on the ol' luck side of things.

[Met4Cast]

2 minutes ago, Man With Beard said:

Woah woah woah, what's all this "ECM capitulates to the GFS" or "GFS wins" talk? The scenario in question is still 7 days away! It's far too early to cast judgement!!

But I'm still enjoying this evolution. If it lands halfway between the ECM of this morning and tonight, the UK will be in the cold "sweet spot"

Some can't help themselves.. one run of the ECM to a more blocked pattern and suddenly it's a certainty, I guess we'll ignore all the previous un-interested ECM runs & the complete lack of recent EPS support (still awaiting the 12z suite with interest)

The complete lack of cold on the ECM is concerning, even less cold than the GFS, but that's just details, plenty of time for that..

[northwestsnow]

Surface temps ..

Colder the further North and West you head,basically.

We could do with a gentle nudge east of the pattern...

Which is entirely possible.

[Lukesluckybunch]

Well then as I was saying earlier what we didn't want was everything too far West and that's exactly what happened.oh well still some time to correct the whole pattern east,but I must admit it's very frustrating.it's crucial in terms of which precipitation we get.we need the shift eastwards to start pulling down some better uppers from the north..please would appreciate it you agree with me on this.thankyou

Edited December 20, 2020 by Lukesluckybunch

[Vikos]

We will see a lot of Modell swing within the next days... 168+ should be noticed, but not more...

The exact locations of highs and lows will be mostly within 72h range. Minor changes there make big differences in outcome of cold or mild

Edited December 20, 2020 by Vikos

[Methuselah]

2 minutes ago, stewfox said:

What Artic are you referring to ?

The one Kris Kristofferson was driving, in Convoy! 

[Scott Ingham]

22 minutes ago, Djdazzle said:

Far too much over analysis going on. The broad pattern is encouraging for cold. Exact details will be resolved over time. Pointless predicting rain, sleet or snow at this range.

Exactly. This is the mindset to take forward. Small upgrades can and probably will keep coming. There shouldnt be any pesimism its not needed. Lets nail the long wave pattern first

[Lukesluckybunch]

5 minutes ago, northwestsnow said:

Surface temps ..

Colder the further North and West you head,basically.

We could do with a gentle nudge east of the pattern...

Which is entirely possible.

Yes I think the set up currently reflects that,I would imagine 2/3c north,5/6c south.

[Scott Ingham]

23 minutes ago, Mike Poole said:

Just one more thought on the ECM, here T240:

Look west.  Where on earth are bad things going to come from in that direction?  If we miss out on this event snow wise then more should follow, there is no sign of anything to drive weather over the Atlantic.  

This is where if my thinking is correct we should see the low heights sink south and our high sucked into a vaccum near griceland. Im thinking north easterlies following into end of first week in Jan

[weirpig]

19 minutes ago, Scott Ingham said:

Heres where yet again you have to factor in model bias. As we hit 96 and under expect corrections East. We need to nail the high first. Dont panic. Were in a tremendous place 

Err  yes  I know   I was replying to a comment  based on that 12z run in isolation    I think most know that these systems have a tendency  to shift East   with time   so as you say no need to panic   but as the ecm run  shows  the evolution at the moment  is not perfect 

[Tim Bland]

Interesting signal for snow chances overnight 24th in the south. Over half of the runs have snow...

[claret047]

56 minutes ago, General Cluster said:

And, what with Uppersgate being still unresolved, I'll wait until I see snow blowing past my window!

And you live in a basement.

Seriously though it all looks very promising from the Big 3 now. I'm really looking forward to see the northerly develop on the charts as the days evolve. It makes really interesting chart watching. Hopefully for once it will fall into place.

Kind Regards

Dave

[Lukesluckybunch]

1 minute ago, Scott Ingham said:

This is where if my thinking is correct we should see the low heights sink south and our high sucked into a vaccum near griceland. Im thinking north easterlies following into end of first week in Jan

I would kind of agree with you there scott,that's a possibly past day 10.but it's very difficult to tell anything could happen,though what doesn't look likely currently is a return to westerlies and Atlantic weather,but if we continue having to chase day 10 charts it can become very frustrating

[Mr Frost]

Evening all!

Taking off my Scottish weather bias spectacles for a moment...risk of wintry showers/snowfall over high ground on Christmas Eve for Eastern England! North York Moors looks the sweet spot on current output. 

Latest UKV snapshot for 24/12: 15:00

Precipitation type and sea level pressure:

 

How about this for Santa Claus arriving!? Very festive! 

Snapshot for 25/12: 03:00

 

There is also a wee chance of a wintry shower popping up in the Norfolk area - could be one to keep an eye on for any bets placed on Norwich!

25/12: 03:00

 

All the above subject to change at this range of course but it is looking very seasonal for many! 
 

All the best to you all! 

Edited December 20, 2020 by Mr Frost

[damianslaw]

A word on comments about uppers, it's one factor that influences precipitation type, but just one, crucial other factors include:

Thicknesses - generally sub 528 dam air is needed for snow

Dewpoints - need to be 0 or below, crucial and usually cannot be forecast with any accuracy until 24 hrs

Uppers - well I've seen snow fall and lie with uppers barely below 0 degrees

Intensity of precipitation - cannot be forecast until the precipitation is overhead, heavier it is, greater chance of evaporative cooling

Wind strength - lighter winds or slack airstreams increase chance of snow

Lapse rates - drier continental air tends to be better than maritime air for snowfall

Many other factors come into play, local topography, time of day, surface temperatures etc etc.

Please do not get hung up on uppers alone. We saw in early December snow falling in less than particularly cold uppers, parts of the Fens and south coast had lying snow, and this was not forecast well until the snow was falling out of the sky!

Edited December 20, 2020 by damianslaw

[Scott Ingham]

14 minutes ago, Met4Cast said:

Some can't help themselves.. one run of the ECM to a more blocked pattern and suddenly it's a certainty, I guess we'll ignore all the previous un-interested ECM runs & the complete lack of recent EPS support (still awaiting the 12z suite with interest)

The complete lack of cold on the ECM is concerning, even less cold than the GFS, but that's just details, plenty of time for that..

Its mot just one ecm run though is it? Its the past 9 gfs runs and the fact gfs knows how to model this pattern. Those who have seen it all time and again were waiting for the ecm to junp on board like it did 2018 and 2010 and -5uppers with l9w heights a slack flow and sub minus dew points will produce snow somewhere. We just dont know where yet but it will not be all rain. Its frustrating saying the same thing over and over hahaha its like people psychologically are trying to find the first negative so they dont build hopes up! Hahaha! 

[Lukesluckybunch]

1 minute ago, damianslaw said:

A word on comments about uppers, it's one factor that influences precipitation type, but just one, crucial other factors include:

Thicknesses - generally sub 528 dam air is needed for snow

Dewpoints - need to be 0 or below, crucial and usually cannot be forecast with any accuracy until 24 hrs

Uppers - well I've seen snow fall and lie with uppers barely below 0 degrees

Intensity of precipitation - cannot be forecast until the precipitation is overhead, heavier it is, greater chance of evaporative cooling

Wind strength - lighter winds or slack airstreams increase chance of snow

Lapse rates - drier air tends to be better than maritime air for snowfall

Many other factors come into play, local topography, time of day, surface temperatures etc etc.

Please do not get hung up on uppers alone. We saw in early December snow falling in less than particularly cold uppers, parts of the Fens and south coast had lying snow, and this was not forecast well until the snow was falling out of the sky!

Hi so given the current output would you say snow is likely,I mean are any of the models showing anything cold enough?

[damianslaw]

2 minutes ago, Lukesluckybunch said:

Hi so given the current output would you say snow is likely,I mean are any of the models showing anything cold enough?

Just based on current outputs and this is by no means a forecast, thicknesses are conducive for low level snow, and the slacker airstream will probably help as well. As I said dewpoints are the crucial factor and we can't say for any certain what these would be until the very very very near timescale.

Edited December 20, 2020 by damianslaw

[sheikhy]

2 minutes ago, Scott Ingham said:

Its mot just one ecm run though is it? Its the past 9 gfs runs and the fact gfs knows how to model this pattern. Those who have seen it all time and again were waiting for the ecm to junp on board like it did 2018 and 2010 and -5uppers with l9w heights a slack flow and sub minus dew points will produce snow somewhere. We just dont know where yet but it will not be all rain. Its frustrating saying the same thing over and over hahaha its like people psychologically are trying to find the first negative so they dont build hopes up! Hahaha! 

Absolutely spot on mate!!!

[Scott Ingham]

9 minutes ago, weirpig said:

Err  yes  I know   I was replying to a comment  based on that 12z run in isolation    I think most know that these systems have a tendency  to shift East   with time   so as you say no need to panic   but as the ecm run  shows  the evolution at the moment  is not perfect 

We dont want it perfect now as well end up too far east come T-0 where we are now with the evolution is perfect as we factor in historical shifts east nearer to time in thid set up