Model output discussion - 7th January onwards

[karlos1983]

Some might say the GFS has not changed, but you try telling the NE USA Snow chasers that. They've gone from an all snow event, to a snow/rain event because the low takes more of a land track than a just off the coast track.... That's good news by the way for us down stream! More chance of it flattening the pattern if it heads out off the coast.

Edited January 15, 2019 by karlos1983

[Singularity]

 

Comparison with ECM 00z on the right shows that GFS is now getting close with that vigorous low off Canada (it's tighter and deeper than the 06z) so should show more amplification across the N. Atlantic than the 06z had, but remains very different just N and NE of the UK with LP being taken east with no resistance. This may be to do with the regional stratospheric influence above that region (+ve height forcing).

[SMU]

Agreed with the above -UKMO corrections West towards the ICON & ECM ( who wpuld have thought it !)

Particularly like the 96 slack flow from the SE screams evaporational cooling into any frontal band !

[nick sussex]

8 minutes ago, karlos1983 said:

Decent UKMO at 144, nice sharpening of the trough near Greenland, heights trying to build to the N or the UK.

It would have been even better if the storm over the ne USA wasn’t so flat . Huge differences upstream . The UKMO has little phasing of northern and southern stream jets .  If it  develops the storm more and runs more ne you end up with the sharper downstream pattern . I have to say I’m very dubious of its handling of that storm .

[P-M]

Can I just ask the posters that say 8/10 or 9/10 for a model run; is it scoring the severity of a cold spell or just the evolution or accuracy that you mean?  Just curious as this confuses me sometimes.

 

Apologies if this comes across as a really stupid question but the difference in meaning would help.

 

 

TIA

[snowray]

6 minutes ago, northwestsnow said:

I'm happy with UKMO 144- 

At 120 i wasn't sure but its following EC in its progression..

Yup looking very good to me as well, pity we can't view the T168 chart any more. Bodes well for the ECM later though.

[shaky]

6 minutes ago, Steve Murr said:

Agreed with the above -UKMO corrections West towards the ICON & ECM ( who wpuld have thought it !)

Particularly like the 96 slack flow from the SE screams evaporational cooling into any frontal band !

Yup and it looks like what could be a band of snow across western england!!gfs takes it all the way to the east coast but its still correcting west!!

[Tim Bland]

Band of snow pushing south on Tuesday on 12z GFS

[karlos1983]

9 minutes ago, nick sussex said:

It would have been even better if the storm over the ne USA wasn’t so flat . Huge differences upstream . The UKMO has little phasing of northern and southern stream jets .  If it  develops the storm more and runs more ne you end up with the sharper downstream pattern . I have to say I’m very dubious of its handling of that storm .

Yes good point Nick, I was paying so much attention to that same low on the GFS, I forgot to look upstream on the UKMO. Arguably the GFS deals with it more beneficially from a downstream perspective than the UKMO... did i just say that  

Which results in the GFS being more amplified in the Atlantic at 144

Edited January 15, 2019 by karlos1983

[Day 10]

The ICON has a band of rain, sleet & snow moving through on Friday.

[Singularity]

 

Slight timing offset but GFS is not far away from the ECM 00z now... this at least lends further credence to that ECM run as the most probable sort of route forward.

Just that area N and NE of the UK continuing to be handled very differently by GFS. To counter that, it'll need to seriously pump the mid-Atlantic ridge northward as per the 00z ECM... and find some sudden height rises N of the UK if it wants to match that run even more closely.

[nick sussex]

The GFS has trended towards the ECM and developed a more amplified US storm.

The UKMO looks all wrong over the USA at day 5 and 6 , this effects how east the pattern is over the UK.

The storm on it weakens rapidly and turns into a shallow wave . Completely against what’s expected . I really think it’s lost the plot upstream .

A very unlikely solution which will hopefully meet the shredder by tomorrow .

[snowray]

7 minutes ago, Tim Bland said:

Band of snow pushing south on Tuesday on 12z GFS

Quite a lot of snow around middle of next week.

[Singularity]

Okay, for fun, I will air this possibility for how it could go from here if the usual model bias can be overcome: 

The dig of the trough down west of the Azores continues, pumping up heights just NW of the UK to work alongside those just N of the UK and advance toward Greenland as the Canadian vortex lobe comes apart at the seams.

[SMU]

Just glancing at the 12z GFS- thats the best 'match' to the ECM in a long while-

Great timing to allign as well!!

[knocker]

A borderline rain/snow event on Tuesday as a front is pushed south east t(academic at this stage) but more to point is the ongoing energy/amplifying ridge battle

Edited January 15, 2019 by knocker

[ICE COLD]

Interesting chart around day 9 on GFS 12z . Going for scandi. 

[Mucka]

5 minutes ago, Steve Murr said:

Just glancing at the 12z GFS- thats the best 'match' to the ECM in a long while-

Great timing to allign as well!!

Are you talking about the split energy at 168 Steve or upstream in FI?

It seems quite different both earlier and later which forces the pattern much further SE

Edited January 15, 2019 by Mucka

[tight isobar]

47 minutes ago, tight isobar said:

Were deff-going ec 00z route here..

And gfs could possibly end up with a screaming scandi height notion..

Or back up @-around greenland..

 

@ICE COLD..

She does indeed..

Just the late early/mid level time frames that need a shack up !!

@scandi../ @greeny...

Edited January 15, 2019 by tight isobar

[Leo97t]

Gfs is not bad. Quite cold at the surface by day 10. Maxes of about 3c in London. Still not as good as the ecm though

[Singularity]

Yes this is fascinating now. It's developed an extra LP just SW of Greenland to stop the UK-Scandi ridge heading NW as I envisioned could happen (typical, ha!) but there's three ridges amplifying poleward at once as of D10 due to the Pacific ridge building faster than the 00z ECM had it doing.

Results speak for themselves. At last we see another GFS run that finds the vortex split. Only took it three days longer than ECM this time .

[ICE COLD]

What a crazy NH view . 

[ptow]

1 minute ago, Singularity said:

Yes this is fascinating now. It's developed an extra LP just SW of Greenland to stop the UK-Scandi ridge heading NW as I envisioned could happen (typical, ha!) but there's three ridges amplifying poleward at once as of D10 due to the Pacific ridge building faster than the 00z ECM had it doing.

Results speak for themselves. At last we see another GFS run that finds the vortex split. Only took it three days longer than ECM this time .

A scandi but wrong shape and no real cold to tap into alas

[kold weather]

A better run again from the GFS as we get the mid Atlantic ridging that the ECM has been advertising which Shepards down some colder air

Whilst messy it is a good run from the 12z especially with how it handles the arctic.

[tight isobar]

2 minutes ago, ICE COLD said:

What a crazy NH view . 

Not really crazy as far as split pv and other dynamics go..and is pulling massively forwards..

Whats crazy is how the gfs models it..

Yep..that IS INDEED CRAZY SYNOPTICS!!!