Model output discussion 10/02/21

[Mike Poole]

I’ve not posted much in the last few days, and had accepted an Atlantic dominated period of weather for the 10 day outlook on the models.  But BIG change today in my view.  And it shows up massively in the ECM 12z clusters.  Remember the blue border is +NAO -> Atlantic, and the red border is Scandi block, before you look at the detail.

First T72-T96:

All blocked.  T120-T168:

Atlantic breaking through on cluster 2 only.  T192-T240:

 

All looks locked and loaded for a Scandi block of some sort, for us, we need the right alignment, and no other things in the way.  This will be the focus of the next, and probably, last chase of winter 2020/21. ? And we’re off...

Edited February 18, 2021 by Mike Poole

[Frosty.]

I think the best route back to cold is from high pressure building in and the GEFS 12z mean plus the ECM 12z... (plus Exeter)!..............is suggesting late Feb / early March will see pressure rising in the vicinity of the u k..of course there’s no guarantee the high would position / orientate itself favourably but there’s an increasing number of cold perturbations longer term and looking at the bigger picture there’s plenty of cold around to potentially tap into...anyway, enough waffle from me, I’m still drooling over these GFS 12z operational charts...hope I see them again in the reliable timeframe eventually!  ️ 

 

[Lincs Observation]

Evening all I don’t normally post in this thread I’d rather observe, but going on the model outputs the chance for a sustained cold snap are fading fast with what could be 2 -3 weeks of any cold window remaining I’m starting to look forward to the graduation of warmth into spring. The charts from my untrained eye seem to be starting to move in that general direction.

 

LO

[SqueakheartLW]

Just hoping I can spot a trend here between the GEM runs and GFS runs as we have progressed through the day

GEM 00z vs GEM 12z

First I have posted the ensembles chart from the 00z GEM with all members removed that don't get to at least -5 or lower at 850hpa from the 28th February onwards

A total of 9 of 21 members getting to at least -5 at 850hpa on or after 28th February even if some of them are very brief. Next I will show the ensemble chart again with just the members that get to more substantial cold with -10 or lower.

On this occasion only one member, P03 gets down to -10 at 850hpa for a very brief moment so overall not a very cold update in the later stages of the GEM 00z

How does this compare with the 12z GEM

First we have the ensembles chart for 12z with the -5 or lower rule applied as with 00z for 28th February or later

A total of 11 of 21 members gets down to at least -5 at 850hpa on or after 28th February even if some are very brief. This is a slight upgrade on the 00z so we are heading in the right direction at least here for something a bit colder. However for more substantial cold we need to see the -10 category.

This one is simple as none of the members gets down to -10 on the 12z so a slight downgrade here but generally evens out with the -5 upgrade.

GFS 00z vs 06z vs 12z

How does GEM compare with GFS and how do each of the GFS runs compare with each other too. We shall start with the 00z and like before I have removed all members that don't reach the -5 at 850hpa or lower from 28th February onwards

A total of 26 of the 32 runs get down to at least -5 at 850hpa on or after 28th February so a very good amount and this means a decent shot at something colder in early March but how many of the members get down to at least -10 in the same period.

A significant drop in members here and in fact only 6 of the 32 get to at least -10 or lower but this is at least better than either of the GEM runs could produce so GFS 00z is at least more bullish about cold than GEM is

How does this compare with the 06z GFS

As always we start with the -5 category

A total of 23 of the 32 runs get down to at least -5 at 850hpa on or after 28th February so a slight downgrade from the 00z which is a step in the wrong direction. What is the more important cold category however is the -10 one

As with the 00z a significant drop in members and with 06z only 6 of the 32 runs get to at least -10 or lower which is a match on the 00z but combined with the lower total in the -5 category means overall 06z GFS is a downgrade on the 00z

Finally time to look at the 12z GFS

As always we begin with the -5 category for 28th February or later

A total of 21 of 32 runs gets to at least -5 or lower at 850hpa on or after 28th February. This is yet again another downgrade on the 06z and is yet again another step in the wrong direction for cold fans. How does this stack up with the -10 category and will this look any better compared with 00z or 06z

The worst one yet for the GFS with only 3 of 32 runs getting to -10 or lower but at least the operational run was one of them. Not that it means the operational will verify but higher resolution run could mean a better chance

Summary

Overall downgrades throughout the day which makes grim viewing if you want another cold spell as a last winter treat before spring arrives properly but if you are a fan of an early spring then you must be viewing the model output at present with delight and glee

Total Members

                     -5 or less     -10 or less

GEM 00z     9 of 21         1 of 21

GEM 12z     11 of 21       0 of 21

GFS 00z      26 of 32       6 of 32

GFS 06z      23 of 32       6 of 32

GFS 12z      21 of 32       3 of 32

[damianslaw]

3 hours ago, ICE COLD said:

With runs appearing like this I’m definitely being drawn back in . One last beast for everyone with widespread snow please

Something different to look at I guess than the mild SW flow we are currently enduring and look like doing so in the main for the next 7 days, before signal for heights to ridge through and into the UK cutting off the mild feed.

Early March not too late to receive a potent cold snap still despite the growing strength of the sun, and indeed northerlies and easterlies become more likely from late Feb onwards as we move through Spring when the atlantic is traditionally at its quietest, so not at all unplausible, especially given we will still be experiencing the lag effects of the SSW, and the MJO in phase 7 effect.

In the meantime, not much change as mentioned, very mild in SE parts, certainly this weekend will feel more akin to April than Feb, but the sun is still relatively weak so it won't quite have that fresh Spring feel, give it another month and such synoptics would certainly have people saying Spring is here, but rather early still to blow the cobwebs away just yet..

Hoping we see an exchange to something brighter by the end of the month courtesy of high pressure overhead, for the west this is an exceptionally 'cloudy' weather pattern, and rather miserable I have to say.. at a time when everyone is longing for 'brighter' days in every way. My mood this week is far lower than last week and I'm sure a key factor is this gloomy dank grey weather.

[Trom]

1 hour ago, Lincs Observation said:

Evening all I don’t normally post in this thread I’d rather observe, but going on the model outputs the chance for a sustained cold snap are fading fast with what could be 2 -3 weeks of any cold window remaining I’m starting to look forward to the graduation of warmth into spring. The charts from my untrained eye seem to be starting to move in that general direction.

 

LO

The models are showing the opposite of what you are suggesting.  Until today (since the cold snap) all have shown constant southerlies and westerlies with the occasional north westerlies caused by lows passing to the north.  Today is the first day where they've suggested height rises and possible cold encroachments from the North East - East.  It's all still a long way out and therefore subject to all the volatility and variability attached to that but the first signs of potential are showing.

[Mike Poole]

Pub run out to T84:

The WAA into the pole will develop the Scandi high (red arrow), the cold could advance (black arrow) but what happens to the high (H) to our east.  It would need to move north for the cold solution.  

[Mike Poole]

And we’ve a 1045 high over Scandi all of a sudden T126 on the pub run:

Lots of work to do to get the cold here, but early doors on this run...

[Griff]

10 minutes ago, Mike Poole said:

And we’ve a 1045 high over Scandi all of a sudden T126 on the pub run:

Lots of work to do to get the cold here, but early doors on this run...

I think it what comes later with amplification from the Atlantic that's going to be the decider... 

180 on the op

[Frostbite1980]

5 minutes ago, Griff said:

I think it what comes later with amplification from the Atlantic that's going to be the decider... 

180 on the op

A bit more amplification and that low just south of greenland could slide?

[Mike Poole]

3 minutes ago, Griff said:

I think it what comes later with amplification from the Atlantic that's going to be the decider... 

180 on the op

Yes, totally agree, T204 and you can really see it:

But the more amplified pattern earlier is also relevant i think, the Atlantic not as strong as some models (or posters) have made out!

[danthetan]

1 minute ago, Frostbite1980 said:

A bit more amplification and that low just south of greenland could slide?

No it will get pulled back to the low exiting newfoundland, with the trough dropping into Scandinavia could allow a gap for high pressure to rise towards Greenland. All way to far out to have any confidence.

[Griff]

2 minutes ago, Frostbite1980 said:

A bit more amplification and that low just south of greenland could slide?

I think 180 is beyond fi, at the moment here's to hoping the tea leaves want any kind of heights at all. Recent runs have suggested this might not happen on the first or even second attempt... 

[Griff]

Just for fun but I prefer the way the pub run is shaping up... 

[Griff]

Alien invasion (possibly predator) on the //

[Frostbite1980]

4 minutes ago, Griff said:

Just for fun but I prefer the way the pub run is shaping up... 

Building blocks beginning earlier on, on this run.....probably lead no where but you just never know.

[Griff]

1 minute ago, Frostbite1980 said:

Building blocks beginning earlier on, on this run.....probably lead no where but you just never know.

This is better

[Battleground Snow]

1 minute ago, Griff said:

Alien invasion (possibly predator) on the //

Haha, although that does highlight how the vortices are pulled apart, which may allow height rises in the gap

[Frostbite1980]

4 minutes ago, Griff said:

This is better

Nice WAA thanks to the deep low to the NW.

[Mike Poole]

Pub run v ECM T240:

Pretty similar, the pub run is sharper,  the earliest we could be looking for cold is about the turn of the month given the current setup, and these both go for it, maybe, with a following wind.  But i think the models this evening have actually counted forward a cold spell by a day or so...we will see...

Edited February 18, 2021 by Mike Poole

[Purga]

18z progressing nicely so far

[Allseasons-Si]

Just joined in the party

News just in...

what a 12z gfs that was and then i saw it was a cold outlier but who cares because it was a cracking run and looks like both the 18z gfs and gfs/p are singing here at 228.

now lets see if the gfs is a cold outlier in the suit later on.

 

[Mike Poole]

Now we’re getting there, pub run T270:

A lot of cold there to come if the angle is right, looking good on this run....it doesn’t matter, by the way, if this is the result of a smaller downwelling from the strat, if it nails the UK it is ok with me!

[Allseasons-Si]

And looking V good at day ten>...

if not pretty identical.

[Trom]

10 minutes ago, Mike Poole said:

Pub run v ECM T240:

Pretty similar, the earliest we could be looking for cold is about the turn of the month given the current setup, and these both go for it, maybe, with a following wind.  But i think the models this evening have actually counted forward a cold spell by a day or so...we will see...

No doubt that the direction of travel has been positive today.  We've gone from predominantly SW/W weather directions across all models out into deepest FI to height rises on both GFS and ECM.  Also over the day each run has looked to build on the previous (GFS).  Still all really out in FI but significantly better than the last 6 days of model watching if you want a cold blast.  Lets hope we can see these heights still being modelled on tomorrows runs.

18Z looking like further improvements at early dates

Edited February 18, 2021 by Trom