Model Output Discussion - cold spell to end Autumn

[That ECM]

9 minutes ago, bluearmy said:

Looking very isolated this morning  - ec too Far East with the slider which becomes more of a diver with too much oomph behind it and not enough wedge ahead of it

To my mind ukmo is in the middle of gfs and ecm rather than with ecm. Not sure I would describe gfs as very isolated but I guess it's how we view things. 

Edited December 4, 2017 by That ECM

[bluearmy]

10 minutes ago, That ECM said:

To my mind ukmo is in the middle of gfs and ecm rather than with ecm. Not sure I would describe it as very isolated but I guess it's how we view things. 

Gfs undercuts the block - its cuts off a big wedge of higher heights which forces the trough to come in underneath rather than slide or dive. The other three main models simply don't. 

Also, ecm driving the trough eas of the meridian mean we lose the Arctic air over the near continent and if a trough sinks over us thereafter it is mixed with Atlantic sourced air which means it won't be cold enough away from elevation for any snowfall. Thicknesses in that day 9 ec chart around 530.  We really need that initial plunge of the the trough to stay down the western side of the uk to deliver a cold spell with decent snow cover 

what could be interesting is that it's unusual for a model to be completely wrong repeating the same solution so any drift to gfs from the others introduces a stronger wedge and a weaker jet which will help us stay on the colder side.

Edited December 4, 2017 by bluearmy

[Wivenswold]

Historical Note: Not that it means a great deal this time round but some may find it reassuring that GFS nailed the start of the cold spell in 2010. Stuck to its guns in FI and charged through hi-res in an unapologetic fashion. ECF didn't come on board until about 5 days before. UKMO didn't look great either at +144. 

Anyway, back to my quiet corner.

[feb1991blizzard]

Somethings got to give here because BBC location forecasts (which are derived from met office data I think), still place us easily on the cold side of the Jet, I say easily because of way below average temps with no sign of PPN, BBC news long ranger says lows sliding with potential snow but UKMO and ECM (the models with most stock placed in them by MO) say probably rain and definitely rain respectively.

[That ECM]

5 minutes ago, bluearmy said:

Gfs undercuts the block - its cuts off a big wedge of higher heights which forces the trough to come in underneath rather than slide or dive. The other three main models simply don't. 

Also, ecm driving the trough eas of the meridian mean we lose the Arctic air over the near continent and if a trough sinks over us thereafter it is mixed with Atlantic sourced air which means it won't be cold enough away from elevation for any snowfall. Thicknesses in that day 9 ec chart around 530.  We really need that initial plunge of the the trough to stay down the western side of the uk to deliver a cold spell with decent snow cover 

Thanks. Could it not be that ukmo is progressing slower and we are unsure which way that would go? T168 might give us the answer?

[knocker]

The ecm engages the high pressure and the block with more intent next weekend thus the jet keeps a flatter trajectory and pushes the trough through the UK on Sunday bringing heavy rain to most places. Once cleared perhaps the Azores HP ridging weakly north east next week awaiting the next trough from the north west

 

[MattStoke]

GFS has the low too far SW, and the e͙c͙m͙ t͙o͙o͙ f͙a͙r͙ n͙e͙. a͙ h͙a͙l͙f͙w͙a͙y͙ h͙o͙u͙s͙e͙ w͙o͙u͙l͙d͙ b͙e͙ i͙d͙e͙a͙l͙.

[Man With Beard]

UKMO - looking at the direction of the Atlantic front at T144, my guess is that it would split, with a new trough formed to the south and another to the north, with that small wedge between them. That could lead to something like the GFS but with the southern portion of the low a bit further north than the GFS shows.

UKMO has a good track record with sliders once inside T144 so looking forward to its next few runs.

ECM has snow for Wales Fri/Sat, the slider is snow for the north only, and possibly requiring high ground.

Edited December 4, 2017 by Man With Beard

[SMU]

40 minutes ago, blizzard81 said:

The forcing from Russia is becoming less and less with each ecm run. The Canadian vortex is beginning to run the show as far as the ecm is concerned. In turn that makes me very concerned. We have had 6 years of this now. 

I think perhaps you need to review the 00z runs in terms of day 8-10 that couldnt be further from the truth.

The overnights continue where they left off all weekend

GFS most amplified, UKMO on the proverbial fence, ECM slightly flatter & the GEM finally being hauled into line.

Based on the most recent form you would predict that the ECM will sharpen up a tad on the PM run..

very exciting times- Day 8 & beyond massive -AO..

S

[Daniel*]

ARPEGE 

Is infamous for overdoing wind speeds irrespective it is the most impressive northerly gale I’ve ever seen. Gales are very likely, let’s just hope it nowhere near to this level - NE Scotland might not be on the map.. 

What also concerns me is a North Sea storm surge..a lot of weather to get our teeth into.

 

[chris55]

We often talk about a middle ground route being a good bet taking a mix of the models to look for a medium term solution.

With ECM taking the slider to Far East and GFS dropping it to far west something in the middle would be perfect  often in these situations we see the pattern back west, we shall see, just need the Iceland wedge to hold on a tiny bit more.

gfs 144

 

ecm 144

 

 

Edited December 4, 2017 by chris55

[Gustywind]

4 minutes ago, Steve Murr said:

I think perhaps you need to review the 00z runs in terms of day 8-10 that couldnt be further from the truth.

The overnights continue where they left off all weekend

GFS most amplified, UKMO on the proverbial fence, ECM slightly flatter & the GEM finally being hauled into line.

Based on the most recent form you would predict that the ECM will sharpen up a tad on the PM run..

very exciting times- Day 8 & beyond massive -AO..

S

Yes although ECM looks poor, if it moves towards the GFS and they meet in the middle, we could be looking at a very snowy picture. Even the ECM remains chilly throughout, with -2 to -4 uppers in the latter stages.

[karlos1983]

4 minutes ago, chris55 said:

We often talk about a middle ground route being a good bet taking a mix of the models to look for a medium term solution.

With ECM taking the slider to Far East and GFS dropping it to far west something in the middle would be perfect  often in these situations we see the pattern back west, we shall see, just need the Iceland wedge to hold on a tiny bit more.

 

that’s what my money is on. In these setups, almost on every occasion the pattern backs west. GFS surprises me, I’d expect it to be showing the ecm outcome and ecm the gfs. Interesting few days model watching ahead

[Kentish Snowman in Yorks]

15 minutes ago, Gustywind said:

Yes although ECM looks poor, if it moves towards the GFS and they meet in the middle, we could be looking at a very snowy picture. Even the ECM remains chilly throughout, with -2 to -4 uppers in the latter stages.

Indeed only a slight move towards the GFS from the ECM (and history tells us we often end up with middle ground scenario) and some areas in the UK might be on the receiving end of a rather large dump!

It does seem that the potential is there for some pretty severe wintry weather to affect the UK over the next 10 days or so which means nothing is off the table at the moment be it severe Northerly gales and the potential for notable disturbances in the flow or low pressures engaging the cold air over the UK and delivering some early Christmas pressies!  

Edited December 4, 2017 by Kentish Snowman

[Dennis]

still nice setting for cold times

[knocker]

Just having a 10 minute muse whilst looking at the later GEFS anomaly. Upstream and over the Pole is pretty much unchanged but it is still indicating some ridging Norwegian Sea into east Greenland whilst pushing our trough south with a suggestion of a negative tilt. This splits the upper flow in the eastern Atlantic with a slack pressure area north of the UK which could lead to some interesting surface interpretations.

Edited December 4, 2017 by knocker

[bluearmy]

Ec mean looks encouraging although the control is close to the op 

two very clear solutions on the spreads (as well as the low cluster inbeteeen )

Edited December 4, 2017 by bluearmy

[Daniel*]

Ignore

Edited December 4, 2017 by Daniel*

[Frosty.]

Just reading some of the comments I thought the arctic blast was cancelled but nope, it's still there..

[feb1991blizzard]

1 minute ago, Daniel* said:

The mean looks very alike to the operational to me?

Better wrt sliders and mean uppers over Britain are better than the op which is a good sign.

[Daniel*]

Uppers are marginally colder on the mean this can help tip the balance between wet and white.

[karlos1983]

1 minute ago, Daniel* said:

Uppers are marginally colder on the mean this can help tip the balance between wet and white.

 

Was just about to post the same, that’s pretty encouraging 

Edited December 4, 2017 by karlos1983

[karlos1983]

UKMO 168 

hard to say with that view, but looks a lack of ridging in the Atlantic 

Edited December 4, 2017 by karlos1983

[Daniel*]

1 minute ago, karlos1983 said:

Was just about to post the same, that’s pretty encouraging 

Yes you can insinuate the ECM op is on the edge of the pack so to speak. So that’s reassuring.

[blizzard81]

42 minutes ago, Steve Murr said:

I think perhaps you need to review the 00z runs in terms of day 8-10 that couldnt be further from the truth.

The overnights continue where they left off all weekend

GFS most amplified, UKMO on the proverbial fence, ECM slightly flatter & the GEM finally being hauled into line.

Based on the most recent form you would predict that the ECM will sharpen up a tad on the PM run..

very exciting times- Day 8 & beyond massive -AO..

S

I do hope you are right and my fears are unfounded. I am talking about something in the more reliable range though. Amplification in the Atlantic is still shown to be around 10 days away and we all know how things can change rapidly between now and then.