Model output discussion - into the start of Winter

[jules216]

31 minutes ago, STRiZZY said:

What do MJO phases 5 and 6 mean for Central Europe?

What I believe its a sandwich of low pressure in western/central Europe between displaced Azores high and ScUral one which may drift toward Eastern Scandi. For Poland/Slovakia we are going to run a risk of SE winds unfortunately for a while but only a slight change in positioning of trough might result in a snowy easterly. We dont need upper much lower then -2 under Euro trough.

[BLIZZARDMAN]

Hi, first post here, just wondering with all the talk about upper air temps, is there a particular stage in winter where they become less important or a point where there would just be more cold air available even from the NW for example?

[joggs]

5 minutes ago, BLIZZARDMAN said:

Hi, first post here, just wondering with all the talk about upper air temps, is there a particular stage in winter where they become less important or a point where there would just be more cold air available even from the NW for example?

Hi and welcome. 

Generally you need the continent to cool quickly for start of winter if we were to receive a continental feed. Also the seas around us are slightly warmer than average. We would probably need a straight northerly or big north easterly to bring cold upper temps this time of year. I'd personally say the best time for the coldest uppers would be last 3rd of Jan to last 3rd of Feb.

As things begin to cool further into the season there is more leeway for uppers to produce the goods if its snow you are after. 2010 was a once in a 100 year event I think where everything aligns perfectly for really cold uppers at the start of the season.

That's not to say it wint happen again further into the season.

Edited December 1, 2020 by joggs

[Catacol]

1 hour ago, Broadmayne blizzard said:

Indeed so Blue if one looks back at cold and snowy spells through the years on the NOAA reanalysis charts you won't find Greenland covered in yellow and orange all the time. It's perfectly possible for the PV to be roaring away in that region with a stubborn block downstream. Glosea is I feel not a great guide to nuances that can occur in our locale. It's really a rather blunt instrument in that regard.

Just like this. Broadmayne must have had a fun week at this time in 1996. In the piddle valley I was up to my knees.....

And this anomaly forecast for Christmas week 2020 really isnt that bad at all. Great for that wave 2 vortex hammering that is increasingly getting talked about.

[Zak M]

12z ICON shows the snow much further north compared to its other run last night.

   

It will definitely feel chilly on Friday though.

[tight isobar]

Not gonna do snaps/compare until all 12z suites have run .. but my bet is a few surprises in the mix @snowfall.. and to reasonable moderate evlevation..@classic watch and see process..in the making !!!

[Kirkcaldy Weather]

10 minutes ago, Zak M said:

12z ICON shows the snow much further north compared to its other run last night.

   

It will definitely feel chilly on Friday though.

 Hopefully still similar in a few days time then I may start to get excited  

[tight isobar]

 Ye-ole Chanel low !!!!.. that is all..@warm/cold sectors needs mass scrutiny..@coming days@real knife edge..@possible nowcast =overheads/precipitation!  # suprises..

Edited December 1, 2020 by tight isobar

[TSNWK]

1 minute ago, tight isobar said:

Ye-ole Chanel low !!!!.. that is all..@warm/cold sectors needs mass scrutiny..@coming days@real knife edge..@possible nowcast =overheads/precipitation!

WTF I like it but then again I'm not entirely sure

 

 

[weirpig]

some snow flying about on Thursday Into Friday  on the gfs 12z    sure may not mount to much   but to see a few flakes  will be great to herald winter 

[Duane S.]

6 minutes ago, tight isobar said:

 Ye-ole Chanel low !!!!.. that is all..@warm/cold sectors needs mass scrutiny..@coming days@real knife edge..@possible nowcast =overheads/precipitation!  # suprises..

Very rare beast at this time of year.

Then it would be low solar influence Vs higher SSTs compared to it being in late winter.

 

[Ols500]

im would like to see some sleet in epsom on thursday/friday would be happy lol atm looks unlikley 

[Weathizard]

I’ve decided I hate those heights over Russia, I often see them referred to as friend or foe on here but I’m trying to remember the last time I saw a winter chart for the U.K. that was helped by having a stonking Siberian/Russian high, every time I see this thing it fills me with dread after that winter a few years ago where it seemed to linger for the entirety of winter.

 

Seems to endlessly tease it’s going to cut off and migrate West only to sink.

[Paul]

For those after a bit more info on what's happening at the moment, @Nick F's latest blog is well worth a read

Feeling wintry with snow risk later this week as we start meteorological winter

WWW.NETWEATHER.TV

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Cold polar air will establish later this week, bringing an increasing risk of snow, mainly for high ground in the north and west, but brief...

 

[tight isobar]

5 minutes ago, s4lancia said:

Very rare beast at this time of year.

Then it would be low solar influence Vs higher SSTs compared to it being in late winter.

 

Agree.  However cover of night and geographic air sourcing WILL definitely be in play here.. the points have to fall at obvious levels.. but I can see a classic rain up the road... snow overload scenario setting up here @ watch this space!!... @broken  record stuff .. but the ecm will be crucial for this.. as the time parameters are it’s forte .. let’s av a look aye?!!...

Edited December 1, 2020 by tight isobar

[BLAST FROM THE PAST]

Chart of the day for me....cold prolonged by UKMO model, LP sliding SE with enough of a ridge to our north to force that and Pressure ridging towards Greenland behind it.....

 

 

BFTP

Edited December 1, 2020 by BLAST FROM THE PAST

[Snow lover 2020]

52 minutes ago, Catacol said:

Just like this. Broadmayne must have had a fun week at this time in 1996. In the piddle valley I was up to my knees.....

And this anomaly forecast for Christmas week 2020 really isnt that bad at all. Great for that wave 2 vortex hammering that is increasingly getting talked about.

What will wave 2 vortex do? 

[Methuselah]

And, it's up to Day 10, on today's GFS 12Z... and, by golly, it's boring!

    

[Matt H]

1 minute ago, General Cluster said:

And, it's up to Day 10, on today's GFS 12Z... and, by golly, it's boring!

    

At least there’s no sign of a definitive Atlantic breakthrough though, seems to be struggling a fair amount to return us to a zonal flow. Whether it leads to anything more interesting is another matter.

[tight isobar]

8 minutes ago, General Cluster said:

And, it's up to Day 10, on today's GFS 12Z... and, by golly, it's boring!

    

Granted.. but that word POTENTIAL.. has to be raised..@going forward @block formation.. 6z these 500s awaiting update.. and sister suites @ecm.. have faith..

Edited December 1, 2020 by tight isobar

[Duane S.]

16 minutes ago, Snow lover 2020 said:

What will wave 2 vortex do? 

If there is a decent and reasonably prolonged wave2 attack on the SPV, the net effect could be to split the vortex, as essentially it is a 'two pronged attack'. How and whether that then propagates down through the stratosphere towards the troposphere is another thing altogether mind you.

I do struggle to see enough umph to do this type of damage for a while yet but at the very least it will unsettle it for now. A very good thing when it is in its 'growing' phase. Then watch as I wouldn't be surprised to see a stronger one, maybe even more of a 'bottom up' wave2, later in December result.

Edited December 1, 2020 by s4lancia

[nick sussex]

The GFS can be summed up as a series of shortwave phasing calamities .

The UKMO looks a bit better as even if that does phase it will be later and further east .

You can see how it goes pear shaped on the GFS , the Atlantic shortwave moves se but the one in the North Sea then gets pulled nw as they phase , the sum total is then relying on a lot to go right after that.

 

[Nick F]

GFS being having a bit of a mare modelling the track of the low on Friday developing from a wave running across the south Thursday night. 06z kept the low across the SE, while the 12z takes it further north and deeper.

06z GFS for noon Friday

12z GFS for noon Friday

This affects where may see some snow as the precip bumps into cold air on the western flank of the low ...

[sheikhy]

2 minutes ago, Nick F said:

GFS being having a bit of a mare modelling the track of the low on Friday developing from a wave running across the south Thursday night. 06z kept the low across the SE, while the 12z takes it further north and deeper.

06z GFS for noon Friday

12z GFS for noon Friday

This affects where may see some snow as the precip bumps into cold air on the western flank of the low ...

Crazy changes at short notice!!cant trust the model at all if it cant get the weather right 48 hours from now!!the ukmo looks diffferent at just 48 hours aswell!!nowcast comes to mind straight away!!!at least its not gone west again

[Eskimo]

2 minutes ago, Nick F said:

GFS being having a bit of a mare modelling the track of the low on Friday developing from a wave running across the south Thursday night. 06z kept the low across the SE, while the 12z takes it further north and deeper.

06z GFS for noon Friday

12z GFS for noon Friday

This affects where may see some snow as the precip bumps into cold air on the western flank of the low ...

Follows the latest ICON in that regard