kumquat

Actually its the humans that came up with the laws of thermodynamics that totally own the model output. To the OP, the equations do not change unless Euler or Newton or Einstein have recently been undone by some other genius. What does change and can only get better is the initial start data and the boundary conditions that are used for each run. And, of course, these could well use historical data and blend that into the programming, but at this point its getting very complex. I would suggest looking up Navier-Stokes for some basic fundamentals on fluid flow analysis. Also check out multiphase flow. Honestly, we cant get this stuff right in a straight pipe never mind in the whole atmosphere, but its getting better all the time and the GFS Parallel has been kind of consistant. edit - of course you're right and the computer programme can get more accurate and take on more data ad infinitum (on what its working with) and the grid can be smaller - like John says vertical and horizontal - but this does all come down to two words that hasn't been cracked yet. Chaos Theory.

Might not get home from work Monday if the Netweather precipitation is anything to go by, its gonna snow all day as far West as Bristol and reaching Devon at times according to the GFS 00z. The -5 850 has cleared most of the UK and most of South East Ireland by 15:00 Monday 14th. Certainly doesn't look like any climbdown to the ECM position with my eyes! I know I have to take these precip charts with a pinch of salt but here's midday Monday 14th according to the GFS 00z - sorry, couldn't resist: And all hell breaks loose on Thurday as expected!!

Not sure if you're replying to me, David so question for anyone - I know the high moves off to the north but for the couple of days before that while the high builds from the south and sits over the UK, and the local forecasters are talking about fog and frost, is this part what is called inversion? I.e. where the surface gets cold - which can help prospects down the line? i.e does that help our temps possibly stay even lower when the easterly (however weak) kicks in?

Also I'm seeing (and I know I shouldn't look at the precip charts this far out) but I'm seeing low enough -5 850s for snow being shown on the netweather GFS 18z charts for possibly flutters from Sunday Night / Monday / Tuesday. To me this seems like an upgrade for the west country / inland areas of M4 corridor. Seems like SE is getting hampered by sea temps while "us inland" are being given the lower land temps? - Again as a newb I'm saying what I'm seeing from the 18z model output here at NW. I realise nobody gives the precip charts much notice at this range but the 18z seemed to bring in colder uppers for over here in the West/ Southern Central. Could this have anything to do with inversion cold from sitting under the high for a couple of days? Love all the input and all the usual suspects are very entertaining and educational - thank you for that!

Hi Kold, I'm not getting this - to me this seems exactly like a "massive severe cold outbreak" - as a model watcher newb can you tell me what I'm missing? I see this from the 18z at T180: (looking at 850hPa temps coming around the top of the low) http://charts.netwea.../h850t850eu.png Edit mid post -lol- I see the -10 850 recedes massively all of a sudden at 192 - is that what you mean? http://charts.netwea.../h850t850eu.png Very excited by all of this and (shame on me) been ramping already amongst friends and colleagues - one time it will pay off and now is as good as ever! (if not the best!)

Mama Mia!

December the 13th is the operational's annual leave. He gets to see santa in the ice cave, leaving mum and dad in the local tapas bar.

I think the main problem is lack of land. Lets have a land grab. Can we pave over the GIN?? "There`s just too much energy coming off the Canadian vortex to our NW compared to yesterday`s runs." Good point - well made.

There are real problems here. The start data (for a start!) is way out of kilter.

Filton Weather station http://www.martynhicks.co.uk/weather/data.php?page=live

Yes - Just saw a clump about the size of a fist!!

Big fat flakes here in Winterbourne noggin and starting to settle on the wet patio!

I'm also in Winterbourne. Just been out in it and its really trying to turn. Half an hour ago it was pure rain. Now its definitely icy. But yes, still sleet really.

Weird sound out there now like. Very icy lumps of snow sounds like rustling leaves as it hits the patio.

Turning to snow NE Bristol.

Is that a trough forming in NW Wales heading SE?

Both Severn Bridges closed. Metre square blocks of ice dropping from the gantrys and smashing vehicle windows. Another day off for me with UWE being closed. Bloody marvelous.

More ppn building to the south of Bristol looking to batter us in a couple of hours

Hi Nevesy and welcome!!!

Snow really tossing down now (scuse my francais)

Absolute whiteout heavy blizzard in Winterbourne. Could be our last ppn for a while, but I'm confident it will build back towards us. Fears of it not covering wet roads have been quashed. Awesome.

Edit: As I typed this very heavy snow has turned my wet patio into fresh white cover and the road is totally white too!!

Goatherd - nice photos!! Coming down heavy and at last starting to settle on the wet roads in NE Bristol. Radar looks like a gap coming up. BUT I think its starting to stall on a SW-NE line through Wales and the PPN looks like its starting to "stretch East". Hoping that this will be more evident within the hour and this keeps Bristol within the PPN. I think we will see a stop as reported in somerset etc. but signs further south of a build further east which will keep us in the picture.

Bristol is having all of that ppn as a streamer :lol: Seriously, if you look at the wind chart that somebody posted a page or so back, it looks like the winds send it to the east as it makes landfall. However, still does look a bit more west than what the BBC are making out. It seems very slow moving also now.

Please let it come this far North and West. Yet another day of radar watching :o :lol: :lol: These forecasts are so "down to the moment" If that main band had been a few more miles to the east last night we would have hardly got anything last night.