Model output discussion - into Christmas

[frosty ground]

finally got the jet looping back around the high.

[Lampostwatcher]

Oi oi 

18z gfs keeps the chance alive 

A finger of high pressure heading to scandy 

Bank that please 

[Allseasons-Si]

The cold is backing west on this run compared to the 12z by the 27th

a look at the de-built ens this evening that i have highlighted shows a nice cluster plus there does look to be more members showing an easterly influence

temps,dew points and wind direction.

 

 

[ICE COLD]

Great run from the 18z . Cold air building out east

[ALL ABOARD]

So far this winter we have had a meandering southerly tracking jet.. 

As soon as we get a scandi block it switches to a powerful northern arm, you couldn't make it up

[Allseasons-Si]

Watch the cold come flooding in from the NE from this trough aligned favorably that wasn't there on the 12z.

 

[feb1991blizzard]

Just now, Allseasons-si said:

Watch the cold come flooding in from the NE from this trough aligned favorably that wasn't there on the 12z.

 

Northern arm a bit strong on this run although good to see signs of the cold making it quite far West - good signs for further into Jan.

[ALL ABOARD]

Just now, feb1991blizzard said:

Northern arm a bit strong on this run although good to see signs of the cold making it quite far West - good signs for further into Jan.

252 low skirting around the bottom of the pv in the atlantic... 

May go under 

[damianslaw]

Once again the 18z GFS showing something completely different to the 6z and 12z, it often does this, one extreme to another. The differences in the 144hr-192hr timeframe continue to be startling, and is indicative of the GFS tendancy I feel to struggle in situations when blocking enters the scene. Early in the week it showed an easterly, once again it is showing some form of easterly possibly developing or at least more of a stand off between the atlantic and the block. A half-way house option may be on the cards, where we see a stalling atlantic struggling to make inroads against the block, and it will then depend on where energy is exerted most into the jet. So far this winter energy has been more in the southern arm.

 

[Allseasons-Si]

Not quiet on this run but V close

baby steps to hopefully a better evolution in subsequent runs.

[feb1991blizzard]

1 minute ago, ALL ABOARD said:

252 low skirting around the bottom of the pv in the atlantic... 

May go under 

Think it will force another ridge to develop and more WAA but with cold just out of sight again but again - bodes well for the future.

[damianslaw]

3 minutes ago, Allseasons-si said:

Not quiet on this run but V close

baby steps to hopefully a better evolution in subsequent runs.

Its a resilient block though with heights up to 1045mb the atlantic could struggle to break through I feel here, we might see some trough disruption squeezing down from the NW, with heights advecting back westwards.. 

[MP-R]

Well as we've seen this month, a southerly tracking jet this winter is going to bring us mild, so perhaps a northerly tracking jet will allow for cold lol. This winter is certainly going against the norm so wouldn't surprise me.

[ALL ABOARD]

2 minutes ago, damianslaw said:

Its a resilient block though with heights up to 1045mb the atlantic could struggle to break through I feel here, we might see some trough disruption squeezing down from the NW, with heights advecting back westwards.. 

Yes here she goes... 

Be surprised if it dosent head for Greenland now.. (all academic at this range of course) 

[damianslaw]

Just now, MP-R said:

Well as we've seen this month, a southerly tracking jet this winter is going to bring us mild, so perhaps a northerly tracking jet will allow for cold lol. This winter is certainly going against the norm so wouldn't surprise me.

There has been a north-south split so far this December, the period 11-17 Dec in the northern half of the UK did deliver some quite cold weather, nothing exceptional, but below average temps and some snow, its just the jet hasn't been quite far south enough to deliver nationwide colder than average conditions. Looking at the very near term outlook, the synoptics are actually not bad from a cold perspective, if everything was shunted about 300 miles further south and east, then we would be locked into a probably quite cold wintry period, alas things haven't quite panned out like this (yet!) - a heck of a lot of winter to go yet, indeed it often doesn't get going until after christmas!

[feb1991blizzard]

Didn't expect the transition from 288 to 300 - you usually get those unexpected transitions on the ECM as its 24 hour steps but that step means an E'ly back on the menu now in FI

[feb1991blizzard]

-8c East anglia and snow showers.

[Allseasons-Si]

3 minutes ago, damianslaw said:

Its a resilient block though with heights up to 1045mb the atlantic could struggle to break through I feel here, we might see some trough disruption squeezing down from the NW, with heights advecting back westwards.. 

Yes the high is forcing trough disruption over the UK at 300,easterly incoming but as you noted earlier in your post the reliable is at 120,so many options on the table after that and although nice to see the 18z show this nice scenario,i remain on the fence until there is some agreement in the next few days.

[feb1991blizzard]

Snap off siberian vortex sector on its way - here comes the mid 80's redux run.

 

Edited December 19, 2019 by feb1991blizzard

[swfc]

Great 18z.woudnt be a bad start to the new yearhopefully still there tom?

[feb1991blizzard]

-8c widely there with -16 with low 500mb heights waiting in the wings - if that makes it with SST's at this time of year - expect an 87 style SE burial job.

Edited December 19, 2019 by feb1991blizzard

[feb1991blizzard]

Here she comes - touch and go whether she makes it.

 

Edited December 19, 2019 by feb1991blizzard

[frosty ground]

Those cold upper I pointed out in the 12z Have come in to play once that jet curves back.

building blocks around day 7
 

 

[Snowy L]

This is why 850hpa temperature ensemble charts are a bit useless at the moment. 5c+ uppers over the UK, but the reality is a huge battle between the Atlantic and Scandi High.

Edited December 19, 2019 by Snowy L

[MP-R]

10 minutes ago, damianslaw said:

There has been a north-south split so far this December, the period 11-17 Dec in the northern half of the UK did deliver some quite cold weather, nothing exceptional, but below average temps and some snow, its just the jet hasn't been quite far south enough to deliver nationwide colder than average conditions. Looking at the very near term outlook, the synoptics are actually not bad from a cold perspective, if everything was shunted about 300 miles further south and east, then we would be locked into a probably quite cold wintry period, alas things haven't quite panned out like this (yet!) - a heck of a lot of winter to go yet, indeed it often doesn't get going until after christmas!

Indeed, my comment was slightly tongue in cheek. It's just amazing to see a strong jet stream hurtling across Iberia and we and most of Europe still get bathed in warm air lol.

Some interesting choices for late month and into January though!