Model output discussion - The run up to Christmas

[bluearmy]

note the system headed over us around day 10 has come from greeny area like previous ones but it’s origins are in that locale and it contains colder air to begin with 

[Man With Beard]

2 minutes ago, Tim Bland said:

And a week ago we were debating if it was even possible to see leftovers from the PV slip over us... now we see it multiple times on one run! 

Wowzaas! This is truly awesome! Snow on northern hills would be through the roof, lamppost watching will become a national pastime

[Allseasons-Si]

6 minutes ago, Mike Poole said:

Yes, and that is the point, repeated re-amplification of the pattern. There isn’t anything upstream to suggest otherwise.  Which is all good as every time it gets colder.  

I didn't mean it in a bad way BTW,it looks better than the first one,keep em coming i say

these pv chunks are like buses,either they don't turn up at all or they all turn up at the same time lol

all good

Edited December 21, 2020 by Allseasons-si
typo

[Cold Winter]

I’ll take this! Reasonable T850s make for nice looking snow cover charts. (Admittedly at T294...)  

Edited December 21, 2020 by Cold Winter

[Tim Bland]

Meh...just the 10cm over London ...hopefully more to come

 

Edited December 21, 2020 by Tim Bland

[ITSY]

Just now, Tim Bland said:

Meh...just the 10cm over London ...hopefully more to come

Indeed! And over Kent for those poor brexit lorry parks 

[Updated_Weather]

Just now, Tim Bland said:

Meh...just the 10cm over London ...hopefully more to come

If only!

[Mucka]

Groundhog Day?

 

GFS 144/288

[Allseasons-Si]

@Scott Ingham

here is your Griceland high

[Joe Bloggs]

4 minutes ago, bluearmy said:

note the system headed over us around day 10 has come from greeny area like previous ones but it’s origins are in that locale and it contains colder air to begin with 

Yes.

Our troublemaker for just after Christmas (uppers-gate) is shown very nicely on the 18z GFS moving off the eastern seaboard in less than 12 hours time. 

Some quite warm air wrapped up in the system. 
 

 

[Allseasons-Si]

6 minutes ago, Man With Beard said:

Wowzaas! This is truly awesome! Snow on northern hills would be through the roof, lamppost watching will become a national pastime

Yes,we would need taller lamp post's

[Matt H]

Deleted.

Edited December 21, 2020 by Frosty Winter

[Scott Ingham]

35 minutes ago, Kasim Awan said:

Depends on the position of the low. The way the GFS models it there would be a fair bit of shortwave / mesocyclonic precipitation. The parameters currently prescribed would support mixed precip; as uppers are moderated around low cores and surface warm layers where onshore winds form. This would support potentially prolonged yet fairly localized heavy wet snow events in areas with both heavy precip and optimal wind dir. Marginality being very significant in the areas noted above.

I do think, just using a statistical law, that some low ground place will get lucky and have precip at the right time, i.e. before the surface inversion and bag a few days of snow cover as surface inversion feedbacks develop. They can do in slack systems to. 

This set up is more interesting to me than the BFTE.

Brilliant. Better described than i could but loosely describes what my thinking was

[Allseasons-Si]

Beautiful run this,colder uppers coming in from the NE

and where has that pac ridge come from?

 

[Joe Bloggs]

Just now, Frosty Winter said:

Deleted.

I saw your post before you deleted it.

To answer your question - look at the progression of the low moving up the eastern seaboard in 12 hours time with the all the warm air wrapped up in it. It’s the same low which will pull south into our NW’ly flow just after Christmas. Not helpful for the uppers. That’s not me saying it won’t snow but agreeing with bluearmy’s point that it’s a factor. 

[tight isobar]

17 minutes ago, Uncertainy said:

The extended JMA builds HP through the UK from the SW 

Meto/BBC extended into New Year suggests this possibility.

Main alternative at day 10 - 11 seems to be another diving trough ala ECM/GFS

Either way there does look to be a second surge of amplification after our Dec 27th event. The location of this amplification may well be our next medium term ‘topic’ in the coming days...

 

In a quick note ;the Japanese model is held in “high regard “ via - leading meteorological agencies.. as a backing tool within 196hrs against the leading sets.. and those behind closed walls.. just putting it out there

[Matt H]

2 minutes ago, Joe Bloggs said:

I saw your post before you deleted it.

To answer your question - look at the progression of the low moving up the eastern seaboard in 12 hours time with the all the warm air wrapped up in it. It’s the same low which will pull south into our NW’ly flow just after Christmas. Not helpful for the uppers. That’s not me saying it won’t snow but agreeing with bluearmy’s point that it’s a factor. 

Yes I totally understand the point you’re making now. I think I misread it at first, hence why I deleted the post so quickly!

[Kasim Awan]

3 minutes ago, Scott Ingham said:

Brilliant. Better described than i could but loosely describes what my thinking was

Set up is optimal for very slow moving shortwave lows. These can outdo snow forecasts by some amount. I think this needs to be our concern / interest.

[Tim Bland]

Most places have snow cover, close to ice days with very little thaw...and no end in sight ..with a SSW up our sleeves ️

[Ben Sainsbury]

Just now, Tim Bland said:

Most places have snow cover, close to ice days with very little thaw...and no end in sight ..with a SSW up our sleeves ️

And now we have an easterly develop by T348, what more could you want!

[bluearmy]

1 minute ago, Ben Sainsbury said:

And now we have an easterly develop by T348, what more could you want!

The run to verify ???  

[Allseasons-Si]

Dare i say it....

we could be latching onto a 2010 evolution here,it would be a great 10th anniversary

wake up SI. 

i will re-post this post if it happens.

Edited December 21, 2020 by Allseasons-si
typo

[Uncertainty]

1 minute ago, tight isobar said:

In a quick note ;the Japanese model is held in “high regard “ via - leading meteorological agencies.. as a backing tool within 196hrs against the leading sets.. and those behind closed walls.. just putting it out there

Well TI its seasonal iteration gave us the most blocked pattern in its November run before it got cold (warm?) feet in December.
 

If the general output for the next 3-4 weeks comes off  as the anomalies suggest and Feb doesn’t go all 2020 on us then that run might well have been spot on.

 

[Ben Sainsbury]

3 minutes ago, bluearmy said:

The run to verify ???  

I was asking for that one

A very cold T384 chart of course to top it all off! Only have to wait 16 days for this to verify...

 

Edited December 21, 2020 by Ben Sainsbury

[Allseasons-Si]

The control is a carbon copy on the gfs at 216

you can see that pv chunk on the 216 mean.