Model output discussion - into 2018

[northwestsnow]

Assuming this does come off as per GEM one really has to take the hat off to this model- it spotted the undercut well before UKMO!!

Of course, crewe could be right and GFS calls it correctly - 

Fingers crossed for a steady as she goes EC- think the GEM/UKMO are our insurance policy this morning- think this thread will be very busy come 6am onwards...

 

[West is Best]

Gosh what an interesting period of weather. How often have we noted that a shaken Atlantic can lead to something special? I'm sure Mr Murr mentioned this on here ten years ago.

The essence of this is what happens at T132. All models are agreed that Saturday / Sunday are going to be bone-chilling off a north-easterly. Look at the UKMO for Saturday / Sunday:

And the GEM:

It's what happens to the Scandinavian high around T132 which is critical. The overnight 0z GEM and yesterday's 12z ECM see it retrograde north, pulling Britain into a spell of biting easterlies the like of which we've not seen for a long time:

Which, although often dry, can bring some substantial snowfall from setups such as this:

 

So, what of the 0z GFS? Well it always struggles with easterly setups. We've seen this so many times. Often it proves correct. But that's more because easterlies are rare beasts. I think there may be a set algorithm within GFS that opposes any counter-current wind direction, which is what an easterly is. I therefore find it encouraging that nowhere in the latest run does the GFS return us to an Atlantic westerly flow. What instead it sees as the plausible outcome is the Scandi high around T132 to sink south into Poland, thus cutting off the cold source:

UKMO 0z offers a very cold run but we don't know what would happen to the high at T144. Would it follow GEM and retrograde north again? Or sink as per GFS? All we can say is that the GEM is very similar at the same point.

All eyes therefore on the 0z ECM and the GFS ensembles. I'm particularly interested to see how much support there is for the GFS operational. My suspicion is that the GFS is being to crack ... but you've got to back the form horse really. It's still the gold standard model. Here's hoping it has got this one badly wrong, and the latest GEM and yesterday's 12z ECM are right. 

 

 

[Daniel*]

4 minutes ago, Ali1977 said:

I was surprised to see such consistency from the GEM, it may be right or wrong but a model with consistency is good if you ask me and should be taken seriously. I think we are now looking at atleast 6-7 days of cold air, with frosts and some snow showers around.  Probably the best cold spell for 4 years so that’s not to bad after 2 good snow events for some in Dec.  Could be some pretty severe frosts in places, especially if snow cover although I’m not sure there will be too much of that away from east coasts maybe.

if this next ECM has another great run I’ll be a tad surprised however, but I’m keeping fingers crossed. GFS was a slight shift for the better too.

Indeed. I take my hat off to GEM I forgot who said it but apparently it was the first model to pick up on the easterly this is now a dead cert. I can not fault it’s consistency and with UKMO this morning - very encouraged. IMO the chance of a decent cold spell has increased this morning with a greater length to it. Watch ECM 00z decide to play Scrooge these elusive easterlies are the most foreboding synoptics! This is a very good time of year for it. 

[Daniel*]

GEM appears to be too progressive to me in the block collapsing. It does not look right to me. 

 2 days later > 

 

Edited January 3, 2018 by Daniel*

[West is Best]

1 minute ago, Daniel* said:

the easterly  is now a dead cert. 

Ever since John Ketley forecast an imminent beast from the east which never happened, no-one on here should repeat those words  

[Ali1977]

2 minutes ago, Daniel* said:

GEM appears to be too progressive to me in the block collapsing. It does not look right to me. 

 2 days later > 

 

It goes look strange but look at that blast of WAA heading up from the Atlantic, could reinstate some form of Scandy high , and should keep that low pressure in the MED.

[Cheshire Freeze]

18 minutes ago, northwestsnow said:

Assuming this does come off as per GEM one really has to take the hat off to this model- it spotted the undercut well before UKMO!!

Of course, crewe could be right and GFS calls it correctly - 

Fingers crossed for a steady as she goes EC- think the GEM/UKMO are our insurance policy this morning- think this thread will be very busy come 6am onwards...

 

I'm not saying the GFS is going to be correct though...I'm merely stating we need to proceed with caution as, whilst the GFS is showing this evolution, it remains a possibility.

[Daniel*]

17 minutes ago, Ali1977 said:

It goes look strange but look at that blast of WAA heading up from the Atlantic, could reinstate some form of Scandy high , and should keep that low pressure in the MED.

I agree still continuing in an interesting vein. GFS is making small steps without it make adjustments within T90 it does not inspire much faith in the model - whereas GEM for instance isn’t messing about. 

T99 

18z  00z 

Quite an apparent difference instead of a slack ‘crappy’ easterly on the 18z all down to it struggling with ridge placement turns into a brisk decent fetched easterly/ENE on 00z for the SE for a time..

Edited January 3, 2018 by Daniel*

[Daniel*]

27 minutes ago, West is Best said:

Ever since John Ketley forecast an imminent beast from the east which never happened, no-one on here should repeat those words  

I’m not anticipating a beasterly sub widespread -12C uppers, it will be very cold for a yet undecided length not exceptionally cold but more than cold enough to satisfy coldies I would hope. And even colder air is possible further ahead, if everything falls into place. However let’s get to phase one first, as a southerner this is the first time I’ve felt excited I never want to see a PM cold spell again. 

A beast is more than welcome. 

Edited January 3, 2018 by Daniel*

[northwestsnow]

18 minutes ago, CreweCold said:

I'm not saying the GFS is going to be correct though...I'm merely stating we need to proceed with caution as, whilst the GFS is showing this evolution, it remains a possibility.

no worries mate - 

[Ali1977]

With talking about the latest METO update I’d think even without fully backing latest ECM and GEM models there is some support within their suite - shame we can’t find out the amount. With that in mind another ECM good run must be in the realms of reality, however any shift towards the GFS is pretty notable at this range.  Eyes down, this is a biggy.

[northwestsnow]

Last blinking hour in work before hometime and i can't watch EC come out-

I'm confident it will show similar to GEM/UKMO tho..

[BlazeStorm]

Yikes

[Daniel*]

2 minutes ago, northwestsnow said:

Last blinking hour in work before hometime and i can't watch EC come out-

I'm confident it will show similar to GEM/UKMO tho..

Famous last words... here we are at T48.

[Daniel*]

T96 steady as she goes.

12z  00z 

[That ECM]

T96 that will feel bitter. 

Edited January 3, 2018 by That ECM

[Ali1977]

Well here’s the latest 144 and to me this looks even better, stronger high and looks more undercutty- we shall see next frame 

only concern is heights not as low in Spain and the Easterly is more of a SE’ly, so more chance of collapsing possibly. Atlantic profile of PV looks quite different .

Edited January 3, 2018 by Ali1977

[KTtom]

Blimey you can cut the tension with a knife!!!

Ecm fine at 144, high cut off and heading north...

 

 

Edited January 3, 2018 by KTtom

[That ECM]

3 minutes ago, Ali1977 said:

Well here’s the latest 144 and to me this looks even better, stronger high and looks more undercutty- we shall see next frame 

only concern is heights not as low in Spain and the Easterly is more of a SE’ly, so more chance of collapsing possibly!! 

Ecm is ok but I would prefer ukmo.  Further north on ukmo. 

Edited January 3, 2018 by That ECM

[Daniel*]

1 minute ago, Ali1977 said:

Well here’s the latest 144 and to me this looks even better, stronger high and looks more undercutty- we shall see next frame 

only concern is heights not as low in Spain and the Easterly is more of a SE’ly, so more chance of collapsing possibly. Atlantic profile of PV looks quite different .

I prefer 00z the lower heights in Iberia are important but you are right it does look more undercutty possibly short term pain with the less cold uppers. A more negative tilt rather than the slight positive tilt on 12z to Atlantic express due to stronger block.

[Ali1977]

168 and it’s still all systems go ?? strong Scandy high, next frame could be awesome

Edited January 3, 2018 by Ali1977

[Ali1977]

4 minutes ago, Ali1977 said:

168 and it’s still all systems go ?? strong Scandy high, next frame could be awesome

Atlantic has died and come to a standstill to my eyes, just need to tap into colder air from Russia now ?

Edited January 3, 2018 by Ali1977

[shaky]

9 minutes ago, That ECM said:

Ecm is ok but I would prefer ukmo.  Further north on ukmo. 

You couldnt draw more identical charts if you wanted to!!ecm with the stronger high and looks better to undercut further west!!

[Daniel*]

I knew we’d get there fantastic.

[chris55]

broader pattern solid on EC just orientation of the high not perfect on the 00z (at 168) with regards to 850s, still would be bitter at the surface, would it be cold enough for any undercut to deliver some frontal snowfall? Not sure.

Though small adjustments would drag in the much much colder air.

 

Edit

at 192 orientation adjusts to a much more favourable position

Edited January 3, 2018 by chris55