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Model Output Discussion


reef

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

Thing is, people want snow and not just the cold, i expect many peeps to be disappointed with this run.

This is why members should look at the wider picture.

If you want to look at the models for snow then to be honest don't look at the models until Tues because only then will the detail be sorted out. What members should be checking in the models at the momentis to make sure the general pattern remains the same i.e block over Greenland.

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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent

Thing is, people want snow and not just the cold, i expect many peeps to be disappointed with this run. To me there is signs of yesterday's ecm coming into play with the Northern arm of the jet being to strong consequently heights are lowering a touch.

We might get a Northerly reload for people to ramp over. ;)

People have said this time and time again, looking for snow at this stage is just pointless. With a setup like this, the longer the cold lasts the better, because we then have an increased risk of seeing some very good snowfalls. Lets get the cold here for a couple of days before we start worrying whether we'll see lots of snow.

I'm keeping a close eye on Sunday/Mondays potential for snow in the SE, although its hardly likely to give more than a dusting, or 1-3cm across higher ground, thats also in a slightly more reliable timeframe and the GFS have been fairly consistent with the risk. The 06z GFS run seems to want to bring the PPN and colder air in through Sunday instead of Monday however.

But like I say, lets get the colder air in, and then we can begin snow hunting.

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Posted
  • Location: Skirlaugh, East Yorkshire
  • Location: Skirlaugh, East Yorkshire

It looks to me like the ECM and GFS have settled in the middle-ground today - if we're honest neither model has had it spot on. It has to be said though that the setup progged now doesnt look great for Northern areas. It certainly looks cold enough for snow, but with these areas so close to the high pressure and the flow being slack, there probably wouldnt be much in the way of precipitation.

Indeed, when the main thrust of cold air comes, the precipitation looks rather anaemic everywhere, with the only place that gets convective showers North-eastern areas:

http://www.wetterzentrale.de/pics/Rtavn1264.png

After that the low supporting our high sinks, but good fortune has it that a potent Northerly comes in, so not too bad overall.

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Posted
  • Location: Renfrewshire
  • Weather Preferences: Snow/Blizzards, Storms, Sun, Lightening
  • Location: Renfrewshire

RE: minimal pressure rise over GL.

Don't think that's going to happen Altostratus. It is already building and it is building quite steadily. I think we just need to remember that we are only in December and this is an El Nino winter is it not? And if I am not mistaken the real interest for these sort of winters begin in the New Year. Let's just be happy that the models are hinting at some wintriness and seasonal conditions for Christmas because by god do we need it for our sanity! Another Christmas of 14c and drizzle doesn't really appeal somehow?!!?

Is anyone like me on this run waiting for a true floodgate northerly to open! Out to t~159.

Not the worst run at all, although there is still some confusion within the next 72 hours.

lewis

Waiting? No. Hoping and praying? YES ;)

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

This is why members should look at the wider picture.

If you want to look at the models for snow then to be honest don't look at the models until Tues because only then will the detail be sorted out. What members should be checking in the models at the momentis to make sure the general pattern remains the same i.e block over Greenland.

Good advice Dave, its impossible to put detail on things at this stage, basicallly for the moment all we need to see is Greenie Block and low pressure in the Med, it might seem a bit simplistic but thats it! And in many reload patterns there are alternating periods of very cold uppers to less cold as low pressure heads south as we see here. These charts IMO at the moment are something we haven't seen for years, we've seen ridiculous gfs FI scenarios which show up at T-300 but never survive we're very close to something special here. ;)

Edited by nick sussex
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Posted
  • Location: Milltimber, Aberdeen ~ 80m asl
  • Location: Milltimber, Aberdeen ~ 80m asl

Yes only a minimal 1060 mb high over greenland on this run ;)

Yes, we got there eventually, but that was well out in FI. The key developments are circa T+120. A lot can change between now and then. It will be fascinating to see how this pans out regardless of the outcome.

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Posted
  • Location: Ware, Herts
  • Location: Ware, Herts

Nice looking polar low roaring down on this run at about +180, has to be taken with a pinch of salt however.

IMO some are over reacting - the general outlook is still very cold, and with cold I am happy.

Edited by Tommyd1258
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Posted
  • Location: Morecambe
  • Location: Morecambe

This is why members should look at the wider picture.

If you want to look at the models for snow then to be honest don't look at the models until Tues because only then will the detail be sorted out. What members should be checking in the models at the momentis to make sure the general pattern remains the same i.e block over Greenland.

True, but it would appear in my eyes is that as we get closer to the reliable timeframe, the models underestimate the Northern arm of the jet and consequently heights over Greenland drop.

Compare the charts we have seen, this run is not the best by any means however at least things remain on the cold side but widespread snow would probably not occur on this run as we lose the main bulk of the easterly flow far to quickly and pressure rises killing off any convective activity.

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Posted
  • Location: Weymouth, Dorset
  • Location: Weymouth, Dorset

I think some in the North half of the country are getting agitated as the HP does seem now not to be going as far North as it was once progged to do but this is likely to evolve into a very potent North ot North Easterly later on and give them all a pasting.

If I was being fussy I would have the high positioned a little more NE than it is, we don't want it to slip too far to our NW. But really, I need to give myself a slap for saying that, this is 1060 TRUE Greenland High, in DECEMBER !! ;)

All in all another great run, keeping the same theme just with a slightly different evolution, although did anybody really genuinely expect every run from now on in to be an upgrade on upgrade?? :diablo:

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Posted
  • Location: Dorset
  • Location: Dorset

The 06Z is really continuing the trend of the day which is for a small parcel of high pressure to build as it comes down the Norway coast(probably starting as an advanced surface high with some relative WAA due to the warmer ocean and the colder air down the east side.

As this moves towards us, it cuts off the easterly flow and prevents the LP that would otherwise have given us lots of snow on Thursday/Friday.

Thurs/Fri looks set to be limited to very cold weather and snow showers.(I would add that added into that NE flow ahead of the HP will be assocaited troughs that *could* bring a bit more organised snow and delay the arrive of the HP.

As it moves over us it intensifies and sinks fast south.

The good news here is that we nolonger have the fronts pushing up from the south that might break the pattern down(and might give us lots of snow).

The High looks set to rebuild over Greenland leading to more Northerly or NE outbreaks.

This is a much more realistic outcome IMO, and is still very good.

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Guest North Sea Snow Convection

I think the gist of what I am trying to say is that we don't want the easterly being kept pushed further south over coming model outputs and the cold air push around midweek/Thurs needs to start coming forward in time in tandem with the block staying orientated favourably and positioned far enough north.

It is going to be cold for sure next week, which is great, but in terms of snow potential for the UK as a whole and the coldest air there are questions still remaining at the present time. The trend needs to hold as out our friend heresmile.gif

I certainly agree that synoptically when did we last see high pressure towards Greenland of that magnitude in mid December? A far cry from the usual drossy set-up

Edited by North Sea Snow Convection
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Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL

True, but it would appear in my eyes is that as we get closer to the reliable timeframe, the models underestimate the Northern arm of the jet and consequently heights over Greenland drop.

Compare the charts we have seen, this run is not the best by any means however at least things remain on the cold side but widespread snow would probably not occur on this run as we lose the main bulk of the easterly flow far to quickly and pressure rises killing off any convective activity.

As many of the old hands on here continue to say, the cold snowy winters of yesteryear began with cold and dry the snow comes later.

By T+240 we have a proper arctic northerly providing nationwide snowfall.

http://209.197.11.111/c9s4a5k3/cds/gfsimages/gfs.20091211/06/150/h500slp.png?dopvhost=charts.netweather.tv&doppl=841a626ccf387c1dcf687c4d1ead7706cf687c85&dopsig=27f2bcef1d3ea960f6db36dc713c47fb

And with the jet running so far south, this could continue on and on

Edited by mountain shadow
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Posted
  • Location: Renfrewshire
  • Weather Preferences: Snow/Blizzards, Storms, Sun, Lightening
  • Location: Renfrewshire

I can't see any evidence of this polar low? I don't think it is a polar low. Am I mistaken?

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

These charts IMO at the moment are something we haven't seen for years, we've seen ridiculous gfs FI scenarios which show up at T-300 but never survive we're very close to something special here. ;)

I don't mean to be rude to other members but I think half of the problem is they are comparing this cold spell to previous cold spells and failing to appreciate the general synoptic pattern. What some have to remember is the charts we are seeing within the reliable timeframe differ to what we have been seeing in recent years.

When it comes to snowfall there are two things that spring to mind. First of all surprise snowfall always happens and often with little warning. Secondly I remember the winters in the 80's and sometimes snowfall never used to occur straight away and was often precedded by a spell of cold, dry, frosty weather.

Like you say a simple way of viewing the models is making sure of the Greenland block, LP in the Med. If you have these two ingredients then the chances of snow will always remain possible. Furthermore these ingredients are perfect for a prolonged cold spell.

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Posted
  • Location: Hull
  • Location: Hull

Who knows come the 12z this afternoon we could be looking at a completely different scenario/outcome. The GFS though has thrown all sorts at us, with around 5 different scenario's even in reliable time frame.

As nothing is nailed on as of yet, we do have the ignorance to push this run aside and wait for the next run, i said earlier this week bu saturday 12z we should have a great understanding of whats actually going to happen.

Regarding snow, it's impossible to predict unless you have an obvious easterly screamer. I have always said this and i will never change, i will not forecast snow for anywhere outside a 24 hour time frame. Forecasting snow is one of the hardest things to do. Let's just see what pops up on the radar when we are under the cold air.

Over all i'm happy with this run, not the best, but hey! El nino winter and as of now the 11th of December we have fantastic models with all models showing nothing short of 3 potential re-loads, an easterly N'erly, and northerly, and also the other way around.

Correct me if i'm wrong but i think this is sensational.

Lewis

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Posted
  • Location: East Anglia
  • Location: East Anglia

It’s funny how attitudes change, when this was first programmed everybody was just happy to get the wet and windy weather out of the way and get something more seasonal. Now we are getting to the, it’s not good enough, where’s my snow stage. Please, let’s just let things develop, there is a lot more variations to come from model outputs, this 06z run is just another one. All in all, in my book this is about as good as it gets for mid-December and could bode well for the rest of the winter.

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Posted
  • Location: Cambridge (term time) and Bonn, Germany 170m (holidays)
  • Location: Cambridge (term time) and Bonn, Germany 170m (holidays)

;)

That's the -16 encroaching this area!

http://www.wetterzentrale.de/pics/Rtavn2401.png

A nice Northerly reload in FI there (and not a toppler!) so all in all a much better run than the 0z which was a bit messy in FI and had an area of HP sitting over Europe (the last thing we want).

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Posted
  • Location: Weymouth, Dorset
  • Location: Weymouth, Dorset

As Nick and some others say above it really is as simple as wishing for low pressure in the med and a whopping heights over Greenland. As long as that is the case, sit back and watch the fun. Some need to remember though that there are going to be mild(er) interludes but on the flip side with this setup in place there will also be snow events, potentially big ones. Where and when though? Well let's just get to this setup first...

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Posted
  • Location: Renfrewshire
  • Weather Preferences: Snow/Blizzards, Storms, Sun, Lightening
  • Location: Renfrewshire

End of the run is showing some "lovely" SW'lys moving their way up and shunting the cold out just in time for Christmas ;) Don't you be bad a boy GFS or you will be getting a lump of coal for Christmas!

Edited by WhiteXmas
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Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL

End of the run is showing some "lovely" SW'lys moving their way up and shunting the cold out just in time for Christmas ;) Don't you be bad a boy GFS or you will be getting a lump of coal for Christmas!

With possible blizzards on the northern side for Northern areas if it verified, which it won't.

All in all the pattern continues to play out. Dry for most with an easterly of sorts followed by possible retrogression and a northerly. Cannot be sniffed at for the beginning of winter.

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Guest North Sea Snow Convection

It's funny how attitudes change, when this was first programmed everybody was just happy to get the wet and windy weather out of the way and get something more seasonal. Now we are getting to the, it's not good enough, where's my snow stage. Please, let's just let things develop, there is a lot more variations to come from model outputs, this 06z run is just another one. All in all, in my book this is about as good as it gets for mid-December and could bode well for the rest of the winter.

I agree very much with this and said as much a few times a week ago when the atlantic conveyor was signalled to stop - and before any of the current blocking was anywhere near coming into view apart isolated hints in a few FI charts.

I do think that what i said regarding seeing next Weds/Thurs potential real cold period keep coming nearer into view still holds true, but that does not in any way detract from the already welcome change we seeing as pressure rises in the first stages of the modelled sequence for the block to take residence to our N - and irrespective of whether it snows in buckets or not next week (hopefully it does of course!)

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Posted
  • Location: Renfrewshire
  • Weather Preferences: Snow/Blizzards, Storms, Sun, Lightening
  • Location: Renfrewshire

With possible blizzards on the northern side for Northern areas if it verified, which it won't.

All in all the pattern continues to play out. Dry for most with an easterly of sorts followed by possible retrogression and a northerly. Cannot be sniffed at for the beginning of winter.

True, true, the northerly that the GFS is progging now looks very potent for many areas however this is still outwith the reliable timeframe so it is still squeeky bum time!

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

It’s funny how attitudes change, when this was first programmed everybody was just happy to get the wet and windy weather out of the way and get something more seasonal. Now we are getting to the, it’s not good enough, where’s my snow stage. Please, let’s just let things develop, there is a lot more variations to come from model outputs, this 06z run is just another one. All in all, in my book this is about as good as it gets for mid-December and could bode well for the rest of the winter.

Unfortunately this always seems to happen, to be honest it's akin to almost a miracle to get these charts appearing within T-144hrs and not in la la land past 300hrs. As you say it will develop but at least we have the right things in place to deliver some snow and cold.

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Posted
  • Location: Napton on the Hill Warwickshire 500ft
  • Weather Preferences: Snow and heatwave
  • Location: Napton on the Hill Warwickshire 500ft

This morning is the morning when a 'cold spell; has been nailed on.

This term 'nailed' has come up several times in the last few days.

Yesterday T36 and T48 was 'nailed' then the ECM took the nail out (but that ECM run was suspect).

The only thing 'nailed' is the fog today.

Its clear that the models cant agree T48/T72.

If we 'nail' things say to T72 or T96 we then just post FI charts (because all the rest is 'nailed') and then get surprised when FI doesn't come of.

That easterly has had more nails in and out of it then a coffin in the last week !

Edited by stewfox
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