General Model Output Discussion

[Alex95]

As I have said on other threads, the GFS won't be wrong at this range, why Exeter haven't backed down just yet I don't know. But obviously a big disappointment for Wales and the Midlands will only more cold and dry weather to come later in the week.

I remember when you said the same about the ECM a couple of weeks ago

[nick sussex]

As I have said on other threads, the GFS won't be wrong at this range, why Exeter haven't backed down just yet I don't know. But obviously a big disappointment for Wales and the Midlands will only more cold and dry weather to come later in the week.

I thought gfs was a little better on the post 48hrs timeframe and has indeed backtracked in its later output towards the ECM undercutting the block this morning compared to last nights 18hrs run and the ukmo raw output has gone the other way. The problem here is the low comes in at the same time as the Greenland block strengthens, this is a very difficult balancing act for the models.

As for the Midlands and Wales they would surely get some snow even with the gfs as the low pushes away, surely in these circumstances and going on past experience the lows rarely get as far north as originally progged, this isn't the low trying to oust the block scenario, the block is developing for this reason i expect come the day a slight shift southwards.

Regardless it's interesting to see how this unfolds.

Edited December 28, 2009 by nick sussex

[BristolBlizzard]

You can see why when you look at the fax chart below.

http://www.wetterzentrale.de/pics/brack1.gif

Im thinking come tomorrow places like Bristol, Cardiff could see some very large snowfall amounts. Infact anyone along the M4 or just N is at risk.

hi if its any help are local weatherman who posts on here ian ferguson .. last night was not going that strong for snow in bristol , his morning forcast has changed for snow even past bristol a bit , ian is very much on the ball , but he did say noway sure yet.

You can see why when you look at the fax chart below.

http://www.wetterzentrale.de/pics/brack1.gif

Edited December 28, 2009 by cityatnight2001

[HotCuppa]

this is fantasy island stuff isnt it? id say build the ark its going to very wet with the rain variety sadly in the north west. Too much reliance on the BBC and meto who are fueling this ramping up of snow. I just happen not to believe them, I think the GFS is pretty spot on all things considered.

Southern scotland will be the main battleground for any snow, and when it does fall its going to be major.

Edited December 28, 2009 by HotCuppa

[Archie_Lewis]

Now I'm confused!

Some net weather members =very brief spell of snow turning to rain for my area tomorrow morning!

Latest news24 with matt taylor = heavy snow all day!

His words " from Bristol Chanel along m4 corridor everything north will be heavy snow"

[Methuselah]

Please peeps, DON'T post 'will it snow in x?' messages into the model thread...

[03jtrickey]

GFS already trending slightly southwards at T30. Very slight though, probably only 30-50 miles. The angle also looks slightly more favourable in my opinion.

http://charts.netweather.tv/gfsimages/gfs.20091228/06/30/h850t850eu.png

[carinthian]

Morning all,

Back in the 60s and late 70s,these present synoptics were quite common during the winter months. Forecasts had to be made without the imput of high speed numericals every 3 hours and snowfall computor graphics. Historically in this type of set up the main front never got much further north than the Wash to the Mersey.

However, a decision has to be made now on whether :

a) Is going to be snow or rain ??

How far north the preciptiation will extend ??

Based on the information I have available, I would predict sleet/rain intermittent in the East Midland and the heavier snowfall on the higher ground of the West Midlands and East Wales, probably north of Birmingham. Later the snowfall becoming more widespread across the heart of England and Wales as the front stalls and sinks southwards.

Hope this helps a little. A difficult call as usual, but I wish the forecast would not say RAIN OR SNOW !!

c

Edited December 28, 2009 by carinthian

[Tom D]

I can't help but feel these BBC forecasts will end up letting a lot of people down. I'm still not convinced GFS is so far out at such short range, yet it goes against the other models. Maybe everything is out and we'll end up with something in between?

[Snowaddict]

A definite southward shift on the 06Z GFS evolution...

I make it to be at least 50 - 75 miles in terms of Ireland..

If this were to continue on each consecutive run then by the 18Z this evening it would almost be in line with the other model guidance..

Positive trend in my opinion

[TEITS]

Something else worth considering for those who think the GFS is never wrong at this range. Remember the snowfall in Reading, London, Herts that caused mayhem before xmas? Well the GFS didn't predict this properly until 6hrs out. The Met O/Fax charts did!!

06Z is definately further S.

Edited December 28, 2009 by THE EYE IN THE SKY

[Glacier Point]

That would be my guestimate as well Carinthian.

As noted above, the 06z GFS has adjusted 30-50 miles southward in the crucial timeframe. Given that we have another 3-4 GFS runs between now and closer to the 36-48 hour crux, that could leave us 100 miles+ south of the current projected position for the snow line. As per ECM, GEM and probably UK MET short range model.

Late Tuesday into Wednesday looks particularly good for my locale. I would suggest a wedge from Bridgnorth, Llanidloes down to Brecon across to Hereford and as far east as Redditch and points west of Birmingham look to have excellent potential for the deepest falls wth somewhere elevaed around Kington on the Herefordshire / Powys border hitting the jackpot. That stalling motion and wrap of marginally cooler air plus evaporative cooling on the north-western flank of this system looks to be the crucial forecasting element right now.

Edited December 28, 2009 by Glacier Point

[Archie_Lewis]

Now I'm confused!

Some net weather members =very brief spell of snow turning to rain for my area tomorrow morning!

Latest news24 with matt taylor = heavy snow all day!

His words " from Bristol Chanel along m4 corridor everything north will be heavy snow"

the latest BBC weather graphics on TV do not match what's being said on this forum!

I'm thinking the beeb have this snow too far south

Edited December 28, 2009 by Archie_Lewis

[Mark Parsons]

Morning all,

Back in the 60s and late 70s,these present synoptics were quite common during the winter months. Forecasts had to be made without the imput of high speed numericals every 3 hours and snowfall computor graphics. Historically in this type of set up the main front never got much further north than the Wash to the Mersey.

However, a decision has to be made now on whether :

a) Is going to be snow or rain ??

How far north the preciptiation will extend ??

Based on the information I have available, I would predict sleet/rain intermittent in the East Midland and the heavier snowfall on the higher ground of the West Midlands and East Wales, probably north of Birmingham. Later the snowfall becoming more widespread across the heart of England and Wales as the front stalls and sinks southwards.

Hope this helps a little. A difficult call as usual, but I wish the forecast would not say RAIN OR SNOW !!

c

Agree. If this was 25 yrs ago we would all have been waste deep in snow but I am not convinced that this will be all it is cracked up to be, even at short notice this low could change coarse and they often do, so it is a hard one to call for the meto and BBC, we have been here before..............hope Im wrong, having said that I am a builder and I really want to work this week and not be rained/snowed off!!!!

[snowmadchrisuk]

Alot of people are saying rain to Snow event , I can see it being the other way round. With warmer 850's moving North washing out the -5's then surely what starts off as snow will turn to rain. This is the Snow chart from the UKMO NAE model.

[TEITS]

the latest BBC weather graphics on TV do not match what's being said on this forum!

I'm thinking the beeb have this snow too far south

Pretty much what I said in my post earlier.

Using the M4 is a good guide at the moment as is often the case. However nothing can be taken for granted which is why I say use the radar, Sat for tomorrow.

[West is Best]

Re. the GFS 6z looks very much to me as if the GFS is starting to backtrack. The trend on the 0z of the low not really making it is accentuated on this run, with the -5C 850hPa much further south.

There will be considerable snow potential to the north of the stalled front, wherever that will be! My view is that only the ECM and GEM have a handle on this. I don't think the ppn will make it very far north. Snow for north Devon, south Wales and southern central England before it moves away.

Edited December 28, 2009 by West is Best

[Downpour]

Something else worth considering for those who think the GFS is never wrong at this range. Remember the snowfall in Reading, London, Herts that caused mayhem before xmas? Well the GFS didn't predict this properly until 6hrs out. The Met O/Fax charts did!!

06Z is definately further S.

What a great post again by Teits. Now the GFS may turn out to be right, but to claim "it won't be wrong at this range" as Ian "even larger teapot" Brown has done is patently untrue as Teits has just demonstrated emphatically.

[Tucco]

The 00z op run was the had the precip further North than any other run. The 06z was more likely to show a more southerly limit.

Meto/BBC weather warnings later this morning need to convey the threat of snow further North at least and the uncertainty.

M4 boundary looks very uncertain, this should be made clear to the public.

Mark

[Weather-history]

Something else worth considering for those who think the GFS is never wrong at this range. Remember the snowfall in Reading, London, Herts that caused mayhem before xmas? Well the GFS didn't predict this properly until 6hrs out. The Met O/Fax charts did!!

06Z is definately further S.

Remember this, there was an ongoing debate on UKweatherworld at the time, why the Met was going for it but GFS wasn't.

[nick sussex]

the latest BBC weather graphics on TV do not match what's being said on this forum!

I'm thinking the beeb have this snow too far south

It depends who you listen to! the met office don't just use model data, they also have loads of other info at their disposal, its not just the main low thats causing the big differences its pieces of energy thrown off it that cause the milder air to get further north, if the gfs has overdone these then the colder air will be further south. But even at this stage there are likely to be further changes.

Edited December 28, 2009 by nick sussex

[snowmadchrisuk]

What a great post again by Teits. Now the GFS may turn out to be right, but to claim "it won't be wrong at this range" as Ian "even larger teapot" Brown has done is patently untrue as Teits has just demonstrated emphatically.

I am not saying the GFS can not be wrong at this stage , but the UKMO coming into line with the 850's further North makes me think that the GFS has done very well out of this as it picked it up when every other model was saying the mild air wouldn't leave the South Coast.

[TEITS]

What I do prefer about the GFS is now it isn't making such a song and dance about the SW off the Norway coast. Now this just brings it straight through.

http://www.wetterzentrale.de/pics/Rtavn961.png

Despite the uncertainity being irritating in some respects this is making it more exciting.

[I remember Atlantic 252]

We are all talking about where the Low sets up, but is the air that this is running into conducive for snowfall ? Everything is tight marginal. Don't forget the little systems last Monday/Weds were running into a well established pot of cold air. This is not.

its still running into cold air, -1C here, east wind setting up, will be milder on wednesday but certainly wont be dry all week on the 6Z, that seems a good chart for new years eve and new years day

[80sWeather]

the latest BBC weather graphics on TV do not match what's being said on this forum!

I'm thinking the beeb have this snow too far south

Just watched BBC weather on the BBC weather website,they have a band of stalling snow right across wales to the essex coast ! either they will back track later today or they know something we dont.