Model output discussion - 7th January onwards

[Mizzle]

1 hour ago, feb1991blizzard said:

https://meteologix.com/ie/forecast/2638879-saddleworth/ensemble/euro/snow

Cute charts. Thanks for sharing.

[Roger J Smith]

Yukon and eastern Alaska can be considered one climatic zone along with the Mackenzie valley of the NWT of Canada, and extreme northeast B.C. and northern Alberta. This tends to be a hit or miss area for severe winter cold, although readings between -10 and -25 C are normal up there. The latitude of this climate zone ranges from 59 N to 66 N about equivalent to northern Scotland to central Norway. 

When it does turn extremely cold there, it is usually because high pressure from northeast Siberia has ridged across the Bering Strait into Alaska. Typically the high pressure areas will be slow to move and will eject numerous bubble highs that join arctic highs that form over the southern arctic islands of Canada and in tandem these move south, but when that mechanism breaks down the very cold air can be released across the polar region by ridges that develop over the Beaufort Sea region and begin to extend across towards Franz Josef Land or Svalbard. Those highs then detach and sometimes move further southwest into northern Scandinavia which is the best place for high pressure to promote UK cold spells (although anywhere from Greenland to Russia can work). 

If the trans-polar connection fails, there is also the chance that severe cold linked from eastern Siberia to northwest Canada could retrograde as one large unit from there to northern Russia, the Urals into the White Sea region. This is partly what happened to reinforce the 1947 cold spell (which was well set up long before it overwhelmed the British Isles). The extreme cold showed up in Yukon around mid-January and intensified to all-time record low values in the last few days of the month and into early February. Readings below -60 C were noted near the Yukon-Alaska border on both sides. Whitehorse fell to -52 C its coldest reading on record (1971 managed -47). This severe cold eased rapidly and it was very mild there by mid-February 1947 (above freezing).

Last winter the coldest spell was 1 to 12 February, showing that the lag time was about 26 days to onset of the very cold spell in Britain. So we can hope the connection gets made a bit faster this winter (the cold spell started about a week ago, so reduce the analogy to 19 days). Similar lag times existed in 2013 for both the January and March cold spells (the Jan 2013 case shows up in mid to late December of 2012). Winters from 2014 to 2017 were generally not very cold in the Yukon (Pacific mild air streams in during milder spells and temperatures are almost as mild as you would find in similar latitudes of Norway). 

I did find several examples of winters with severe Yukon cold (e.g. 1966, 1971) where the cold link seemed to work more for central and eastern North America, so perhaps there are two varieties of setups that promote this regional cold, which seems to be prominent in about one-fifth of winters (similar to the UK ratio I presented earlier). Also I found that cold in 1981-82 was achieved simultaneously so hard to say there was a transfer there. Maybe the Dec 81 Yukon cold fed into the Jan 82 UK cold, then the Jan 82 Yukon cold fed the later cold regime for North America which was deepest in late Jan and early Feb. There is no easy 1:1 teleconnection available from this, but I think in this instance with the pole looking like a transfer point, getting extreme cold into regions that are close to the pole is a good thing, it won't just be mild Pacific air streaming across ice fields and back into temperate latitudes (although that might be good enough to get the job done -- 1947 may have been exceptional because of this severe cold relative to normal in source regions).  

[sorepaw1]

I think its eyes down for next weeks model viewing .

Just think in 7 days we could be T84 hrs into the freezer. Possible west based influence to watch for but i don't think its nothing to concern us yet if at all

Lots to play for..

I think I've exhausted my chart posting for a week or so .

Big thanks to the mods for tidying up this thread and smacking some  bottoms..

 

Edited January 10, 2019 by sorepaw1

[kumquat]

18z para sticking to the script

[Mucka]

Okay since the age old debate of eCM and GFS has come up again let's have some unscientific fun.

Here is tomorrow's chart for comparison.

Here is what the 12z ECM showed for tomorrow from the New Year (10 days out) up to 5 days out.

And 12z GFS runs for the same time period

Now here are my thoughts (and yes people will have different ideas about important criteria but for me this are the main ones when attempting to forecast our weather patterns)

Obviously most of this is subjective but looking at the main areas of interest Atlantic heights, Polar profile, European/Scandi heights and general 500hpa pressure profile here is how I see things.

10 days out

ECM very poor in the Atlantic region, better in the polar region but hopelessly optimistic with undercut and amplification

GFS not great but better than ECM Atlantic, fairly poor in polar region, much more realistic with upper flow and lack of undercut

Verdict GFS win by stoppage.

 

9 Days out

ECM Very poor in Atlantic region, Polar region good to see Arctic high but otherwise average, seeing European trough but overdoing it - actually had us in a continental flow with the South under -8 850's

GFS Very decent effort in Atlantic region, fairly poor in Polar region, better alignment of the tough in Europe, no optimistic continental flow.

Verdict GFS win by points

 

8 days out.

ECM Decent in Atlantic region, actually less good in polar region, a little better over Europe still too optimistic with trough and had the SE under -6 850's

GFS Good in the Atlantic region, still poorish int he polar region, similar to ECM in over optimistic continental flow for South but had it a bit further South than ECM

Verdict GFS win on technicality.

 

7 Days out

ECM Very good in the Atlantic region, very good in Polar region, Very good placement of Euro trough (Merit award)

GFS Very good Atlantic region, decent effort Polar region, decent effort Euro trough but not on level as ECM

Verdict ECM win on points

 

6 Days out

ECM Almost perfect Atlantic region, almost perfect polar region, almost perfect Euro region (Top marks, Gold star)

GFS Almost perfect Atlantic region, Decent polar region, Very poor handling of Euro trough

Verdict ECM win by knockout.

 

I just chose the 12z output at random, somebody might like to try the same with the 00z output and see how that fared.

This is really just a bit of fun and banter but for me it does show what I have always believed.

That GFS is very good at working out the general longwave pattern in FI despite sometimes being too progressive while ECM is far too optimistic with splitting energy and amplification if the potential exists.

However, as we get closer things begin to reverse with ECM rapidly increasing accuracy while the GFS can tend to flail around until we get to day 7 and less where the ECM is always clear choice.

One more caveat, the models may behave better or worse depending on the atmospheric state and complexities of the pattern they are trying to resolve.

Please have fun with this and don't use it to bash me and other forum members over the head with, it is not the model gospel, it's just an opinion on some randomly plucked output!

 

Edited January 10, 2019 by Mucka

[snowfish1]

Does the gfs latest run look underwhelming or is it just me?   

[Ali1977]

23 minutes ago, snowfish1 said:

Does the gfs latest run look underwhelming or is it just me?   

It does, but check out the UKMO that’s a proper wedge heading towards Greenland with the PV more vertical into USA means it should put less pressure on eastward progression into the Atlantic etc..., and by Thurs could be very good. If the ECM and some ENS follow that I’d be happy.

UKMO has a much weaker PV over the USA allowing a bigger wedge up towards Greenland. Maybe others with more knowledge will add some bones, is the UKMO ready to deliver the good here????

Very little support from GEFS for the 144 UKMO.

Edited January 10, 2019 by Ali1977

[snowfish1]

4 minutes ago, Ali1977 said:

It does, but check out the UKMO that’s a proper wedge and by Thurs could be very good. If the ECM and some ENS follow that I’d be happy.

Yeah that looks juicy. Also, there is a trend toward lowering heights over Spain etc which is also a good sign

Edited January 10, 2019 by snowfish1

[Ali1977]

P20 shows what can happen in a short time frame 2 days.

[knocker]

Moving on briefly from the short range.

By midweek a much more fluid west > east pattern emerging with the phasing of the colder/warmer air and frontal systems traversing the country. Thus windy at times with periods of rain, snow on norther hills,interspersed with sunny intervals

Edited January 10, 2019 by knocker

[Ali1977]

Icon looks pretty good at T180 with a cold flow from the North, that ridge looks pretty good with the Arctic HP pushing towards it. 

Edited January 10, 2019 by Ali1977

[southbank]

9 minutes ago, knocker said:

Moving on briefly from the short range.

By midweek a much more fluid west > east pattern emerging with the phasing of the colder/warmer air and frontal systems traverse the country. Thus windy at times with periods of rain, snow on norther hills,interspersed with sunny intervals

Good to see you back

[KTtom]

Nice to see the gfs 00z continues to consistently pee on the previous night's party!!...continuously does this for some reason! Anyway, still no consistancy so best advice I'm giving myself if to sum up trends daily not per run. I think this has another week at least of twists and turns before the evolution to cold is determined...if indeed it is going that way.

Edited January 10, 2019 by KTtom

[ArHu3]

11 minutes ago, KTtom said:

Nice to see the gfs 00z continues to consistently pee on the previous night's party!!...continuously does this for some reason! Anyway, still no consistancy so best advice I'm giving myself if to sum up trends daily not per run. I think this has another week at least of twists and turns before the evolution to cold is determined...if indeed it is going that way.

GFS op is the warmest member of the ensemble the 19th and after that one of the mildest 

[northwestsnow]

2 minutes ago, ArHu3 said:

GFS op is the warmest member of the ensemble the 19th and after that one of the mildest 

Thanks Artur, i just checked the GEFS and they look good

[Tom Jarvis]

UKMO best this morning. ECM not as good at 144h let’s see what it brings.

[Lloyds32]

1 hour ago, snowfish1 said:

Does the gfs latest run look underwhelming or is it just me?   

Still not seeing anything around Greenland regarding High Pressure to lock in any cold. High pressure tries to build in the Atlantic and push north, but low pressure around the tip of Greenland says no. Toppling high pressure in the Atlantic with fleeting cold bursts in FI seems the theme. Still waiting for the Atlantic High/Greenland High as touted by numerous charts posted.

[northwestsnow]

EC 192 - COLD.

[SMU]

ICON/UKMO & ECM all pretty well clustered this morning-

thats good enough for me.

ECM very cold 168>192...

[SMU]

5 minutes ago, Lloyds32 said:

Still not seeing anything around Greenland regarding High Pressure to lock in any cold. High pressure tries to build in the Atlantic and push north, but low pressure around the tip of Greenland says no. Toppling high pressure in the Atlantic with fleeting cold bursts in FI seems the theme. Still waiting for the Atlantic High/Greenland High as touted by numerous charts posted.

You dont need massive blocking over greenland

A steering High pressure will do...

[Radiating Dendrite]

1 minute ago, Steve Murr said:

You dont need massive blocking over greenland

A steering High pressure will do...

Yes.

Think people are thinking only yellows and greens over Greenland = cold.

You don't need this, as Steve says small pockets of heights to disrupt the jet is enough. March 2013 had some good examples of this from memory. 

[Skyraker]

Someone earlier was talking about the dangers of a WBNAO, but I can’t see this happening at all and even if it did it wouldn’t make any difference in this setup.

Nothing is going to stop that cold flooding down now.

[northwestsnow]

Improved EC this morning folks!!

PM attacks 168 onwards and day 10 looking good!

[booferking]

7 minutes ago, Steve Murr said:

ICON/UKMO & ECM all pretty well clustered this morning-

thats good enough for me.

ECM very cold 168>192...

What a run from the FV3 para butral cold starts from next week right to the end what a run country snowed in

[Duane S.]

Good UKMO and good ECM this morning. Almost in range on the ECM. Give it a day or two and it could be boom time

Good comments above about GL pressure. Arctic heights are fast becoming a big player here and will steer the cold, we don't need a whopping orange coloured high sat over Greenland, that will possibly come later.

500mb is only one layer if the SPV above is disturbed, as it indeed it VERY much is, the purples will disipate very quickly once Arctic heights start nosing down.