Model output discussion - mid-winter

[feb1991blizzard]

1 minute ago, nick sussex said:

The race continues between the sinking trough and energy upstream .

The sooner the bloated trough sinks and flattens out the better.

Yes - I take it you say that because we don't want the one E Canada > Greenland to engage it.

The only thing I would say though we might not need severely cold uppers with that trough because evaporative cooling, it could be giving us a dumping.

[Cheshire Freeze]

Should be enough of a hang back of heights across Greenland/Iceland from here to make things interesting going forward from this point. As long as you see sufficient heights in this area, you'll see the jet deflect SE across the UK so effectively there will be Atlantic troughing interacting with cold air across the UK.....snow?!

All in FI but all very interesting

[andymusic]

is this something to do with the similar system that hit the usa recently and brought -40c to parts there - if so I see no reason why even with the Atlantic tempering the temps slightly we can't get from this a good snowy dumping

[nick sussex]

Just now, mulzy said:

Indeed Nick - that's where my interest lies...

It’s key to get the trough as far se as possible before any engagement with energy coming east .

As soon as phasing takes place that will stop the trough from clearing. Luckily here energy disrupts with that shortwave and we don’t get the phasing .

[frosty ground]

Potential snow maker beyond 240, atlantic system moving into arctic air thats over the UK

[mulzy]

It all goes crazy after day 10 - ignore for now.  Lots of interest in the day 7-10 period for me...

[andymusic]

if it's to be believed gfs extends the cold and wintry weather to over a week now

Edited January 11, 2018 by andymusic

[Pembroke Dangler]

1 minute ago, andymusic said:

is this something to do with the similar system that hit the usa recently and brought -40c to parts there - if so I see no reason why even with the Atlantic tempering the temps slightly we can't get from this a good snowy dumping

Yes most definitely due to the extreme cold that’s been in that part of the northern hemisphere the sea temps I believe around se Greenland are well below average so the sea has frozen there I believe so less open ocean for the air to modify. Plus this is where early winter has resided for the first 6 weeks. 

[Fozfoster]

10 minutes ago, andymusic said:

right out to a week Saturday and now a northerly

Before this chocolate fire guard melts, not much for a lot of England. still nice to see some might get some snow.

[frosty ground]

Snow Depth at day 8*..... Only after this chart do things get interesting.

Yes we know the GFS overplays the 850's
Yes we know snow charts are useless 24 hours away
Yes we know something else that you want to say about Southern England and how warm it will be.

But we can take from this run is, the potential is there fro snow as early s Monday night how much and how low is to be confirmed.

[shaky]

Was gona say that the recent freeze over the usa could make things much less marginal here!!could potentially be extremely cold and snowy from the north west compared to normal!

[mulzy]

1 minute ago, frosty ground said:

Snow Depth at day 8*..... Only after this chart do things get interesting.

Yes we know the GFS overplays the 850's
Yes we know snow charts are useless 24 hours away
Yes we know something else that you want to say about Southern England and how warm it will be.

But we can take from this run is, the potential is there fro snow as early s Monday night how much and how low is to be confirmed.

I can guarantee the actual snow depth chart will look nothing like that at day 8!

I feel like I am the new @CreweCold!!!

 

[nick sussex]

Given the very good agreement between the outputs with the trough slipping se the next hurdle to lock in the cold is how quickly that clearance takes.

The Russian high is at least an insurance policy here to stop the Euro trough from being bullied east by the Azores high .

Upstream you need the slow progression and heights building ahead of the Canadian low towards Greenland this adds a bit more forcing to that bloated trough which seems to take forever to sink away.

It does get there eventually but it was a close run thing. Overall a good trend from the GFS. 

Lets hope the ECM can put that trough on a diet, less bloat and flatter would be good!

[Singularity]

So a low closes off just NW of Norway having been plopped out by the trough, and this then moves too far east to bring us any snow (before the -ve AAM bias drives a push from the west)?

That's it, I'm calling it - these models must have been modified to do everything they can to find spoilers in the flow 

 

Anyway... this is the first GFS run to retain in the second week more of a wave-2 look to the warming at 30 hPa. Just needs to increase the strength some.

[frosty ground]

Just now, mulzy said:

I can guarantee the actual snow depth chart will look nothing like that at day 8!

I feel like I am the new @CreweCold!!!

 

I don't need your Guarantee.......

But when you say it won't look nothing like that what do you actually mean. 

The distribution of snow looks right to me considering the direction of the wind.

[tight isobar]

I cant decipher whats more crazy??..

The absoulute text book wintryness from the 12z gfs( preety much from monday throughout)...

 

Or that people 'still' are posting-hyperthetical snow charts!!!

This pm incur- is by no way of the norm; and packs a huge punch with the fridgidity/and vent it comes with/from.

There could be mass impactual snowfall anyway from this baby!!...and will be ironed , out with time .

Not going to make comment/analysis on the absoulute massive possibiltes after the pm flow subsides until completion of all 12z today...

                 Gfs12z= corker....

Edited January 11, 2018 by tight isobar

[mulzy]

2 minutes ago, frosty ground said:

I don't need your Guarantee.......

But when you say it won't look nothing like that what do you actually mean. 

The distribution of snow looks right to me considering the direction of the wind.

Locations over 200m (300m probably a safer bet) and you're in with a chance of lying snow.

[Cheshire Freeze]

cold zonal initiation making its way down towards day 4 now...102 hrs GEFS mean-

Day 5 mean 850s colder than the 6z suite

Snow shown fairly widely...impressive on a mean chart more than a couple of days out

Edited January 11, 2018 by CreweCold

[andymusic]

3 minutes ago, tight isobar said:

I cant decipher what more crazy??..

The absoulute text book wintryness from the 12z gfs( preety much from monday throughout)...

 

Or that people 'still' are posting-hyperthetical snow charts!!!

This pm incur- is by no way of the norm; and packs a huge punch with the fridgidity/and vent it comes with/from.

There could be mass impactual snowfall anyway from this baby!!...and will be ironed , out with time .

Not going to make comment/analysis on the absoulute massive possibiltes after the pm flow subsides until completion of all 12z today...

                 Gfs12z= corker....

absoflippinlutely - could be even worse than that - that's only gfs's guess

this will be a wintry week to enjoy - with much more to come - what a different winter we are having this year

bbc still ramping this aswell - they're convinced now

Edited January 11, 2018 by andymusic

[mulzy]

The GEM much faster to bring energy in from the Atlantic at day 10 (akin to this morning's ECMWF).  Is the GFS being too slow I wonder?  This evening's ECM will be interesting...

Edited January 11, 2018 by mulzy

[Cheshire Freeze]

When the GEFS ensemble graphs come out shortly, the 12z is going to prolong the mean at -5/-6 out to day 10 at least

[Nigerian Prince]

59 minutes ago, Captain Shortwave said:

Whatever happens Tuesday looks particularly bitter with a strong to gale force NW winds.

   

Plenty of showers to go with this with a deep unstable flow, I wouldn't rule out snow fall just about anywhere though away from western areas with a little elevation I wouldn't be getting out the sledge just yet. However a set up like this should be conductive for developing more organised bands of precipitation which could give modest accumulations of snow. The GFS may do just this for Tuesday night with a secondary feature zipiping ENE towards the UK.

I guess the main contention here is summed up by the differences between the GFS and UKMO, both pretty much the same in terms of the surface pattern, but the UKMO has 850s around 2C less cold than the GFS which would be pretty muh the difference between snow and rain potentially in this set up.

 That is an extremely cold air mass coming out of Greenland, uppers of -32 to be moderated as it crosses  2000 miles of sea, imagine how cold the temperature uppers would be,  if there was an area of land mass between the UK and Greenland.!  Gender Male, Location  Battersea, ,London.

[shotski]

2 minutes ago, Nigerian Prince said:

 That is an extremely cold air mass coming out of Greenland, uppers of -32 to be moderated as it crosses  2000 miles of sea, imagine how cold the temperature uppers would be,  if there was an area of land mass between the UK and Greenland.!  Gender Male, Location  Battersea, ,London.

There is, it’s called Iceland. 

[northwestsnow]

24 minutes ago, andymusic said:

absoflippinlutely - could be even worse than that - that's only gfs's guess

this will be a wintry week to enjoy - with much more to come - what a different winter we are having this year

bbc still ramping this aswell - they're convinced now

I havent seen any Beeb forecasts yet but the BBC raw looks excellent for frosty grounds location-

Its basically heavy snow showers tues/wed and light snow thur/fri..

(Caveat being he is 300m asl)..

[snowray]

25 minutes ago, mulzy said:

Locations over 200m (300m probably a safer bet) and you're in with a chance of lying snow.

I was thinking 300m, but we have slighly more of a NWly flow now and marginally colder uppers, the heavy showers could well produce temporary blizzard like conditions further down and settling snow for a while at least I guess, very unstable flow too. Looks like we end up with a bit of the PV over us, interesting to say the least and quite a lot of snow likely at altitude in the North and Wales, and places like Buxton and Dartmoor probably too.