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reef

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Posted
  • Location: Carmarthenshire - 100M ASL
  • Location: Carmarthenshire - 100M ASL

I know on liners are frowned upon - what about two words.

What breakdown?

Here's four more words:

Classic South West Blizzard. <_<

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

10-14 days...... period to watch IMO. Renewed attempt at retrogression to Greenland. GFS has touched on this scenario now a few times post 240 hrs over the last few runs. If it appears on the ECM 240 hrs chart over the next few days I will start to invest more certainty into thsi outcome. GFS MAY have picked up an emerging trend.

Aaron

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Posted
  • Location: Castle Howard, North Yorkshire
  • Location: Castle Howard, North Yorkshire

I know on liners are frowned upon - what about two words.

What breakdown?

Yes, I agree, There's no chance of the low presure breaking through that block, and the only place it can go is slide underneath. A continuation of the cold looks the most likely scenario IMO :yahoo:

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

Things are really on a knife edge for southern areas at the moment, I'm seeing general agreement that the milder air on Tuesday/Wednesday probably won't get far beyond the south coast, but the GFS also hints at some warmer air coming into East Anglia and the southeast, and possibly as far as the Midlands, for Thursday/Friday, which is also something to watch for.

GFS 12Z has everything further south than the 06Z- on Tuesday/Wednesday the mild air only makes it into the extreme SW, and for Thursday/Friday the lows are much further south, keeping the cold air locked in everywhere.

This would mean a week of snow cover, which could of course cause serious problems for issues like grit supplies, but bear in mind that the main alternative (mild air pushing up into the south from time to time) may well not address that problem, instead bringing a slow partial thaw and refreezing at night leading to ice instead of soft fluffy snow- which may be no better for those hoping for a proper thaw, as well as being much worse for those who would like to keep enjoying the snow.

John is quite right- this is a real forecaster's nightmare setup! UKMO and ECMWF will be significant.

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

7-10 days time will see PV disruption, trouble is at the moment the PV is too close to Greenland and is fairly strong, meaning that the only way that the cold spell can continue is through the blocking being centred to our northeast. IF the block stays in place for long enough and retains enough strength, once the PV moves or weakens, pressure is likely to rise over Greenland again. That is why it is important that we see the models continue to extend this cold period with the block to the northeast.

IF the PV plays ball and we get the block to hold long enough, you can bank on the next round to be just as severe as the one are encountering now, maybe even more disruptive. That's all pie in the sky at the moment though. Watch the models extend the cold spell over the next few days. No mild spell for at least 2 weeks; that's my take on proceedings anyway.

Aaron

Edited by CreweCold
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Posted
  • Location: Cirencester
  • Location: Cirencester

12Z gfs for cirencester (imby I know) - gives a good indication of how gfs is handling european boundary temps imo

sunday 1pm 850temp -9c 2Mtemp 0c

monday 1pm 850temp -6c 2Mtemp 0c

tuesday 1pm 850temp -0c 2Mtemp 0c

wednesday 1pm 850temp -0c 2Mtemp -2c

thursday 1pm 850temp -0c 2Mtemp 0c

friday 1pm 850temp -2c 2Mtemp -1

shows any flow with a remotely south east component will be darn cold ... although this run is favourable for lp tracks. I wonder what precip type will fall with uppers of 0c .. snow, snow pellets, or supercooled rain ?

sam

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Posted
  • Location: near dalmellington E ayrshire 302m asl
  • Weather Preferences: mediterranean summer
  • Location: near dalmellington E ayrshire 302m asl

will be interesting to see the mets 6-15 forecast over the next fews days very vague or whatrolleyes.gif

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

I think there are signs that we probably will see some retrogression towards Greenland at around T+168 to T+240. How significant this is depends on how far in the Atlantic can get, and how far north the jet goes- in the mildest case scenario we could see Atlantic lows crashing through and high pressure stuck over to the north of them.

The coldest case scenario has shown up on quite a few runs now, and GFS 12Z is one of the runs that hints at it- we pick up our own cold pool next weekend with 850hPa temps approaching -10C and an easterly flow, with high pressure developing generally to the north of Britain.

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Posted
  • Location: Castle Howard, North Yorkshire
  • Location: Castle Howard, North Yorkshire

7-10 days time will see PV disruption, trouble is at the moment the PV is too close to Greenland and is fairly strong, meaning that the only way that the cold spell can continue is through the blocking being centred to our northeast. IF the block stays in place for long enough and retains enough strength, once the PV moves or weakens, pressure is likely to rise over Greenland again. That is why it is important that we see the models continue to extend this cold period with the block to the northeast.

IF the PV plays ball and we get the block to hold long enough, you can bank on the next round to be just as severe as the one are encountering now, maybe even more disruptive. That's all pie in the sky at the moment though. Watch the models extend the cold spell over the next few days. No mild spell for at least 2 weeks; that's my take on proceedings anyway.

Aaron

Appears to me, on the 12z, that there is some decent Warm Air Advection into Greenland, so we may see further hight rises there. :)

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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

Ok dates I have posted for bitter cold and heavy snow periods. 3-5, 7-10 and 14-20. One to add and could be heavy snow event for mainly south is 12th.

OK, synoptic outlook that I have on my method. LP attempts inroads on 12th from SW but gets repelled by strong very cold block to NE and slides under. New Moon 14th has done and still signals LPs to attack from the SW. First two will be channel/N France LPs and will slide under the block BUT inroads of slightly less cold air attacks the south but entrenched cold will mean very heavy snowfall potential for southern UK and Ireland. Third one [20th approx] will barrel across heart of the UK and although less cold, very cold air tucks in as N'ly and NE'ly winds come about with building Atlantic Ridge [well north and Scotland could do very well snowise from this one]. So the breakdown is starting inasmuch that the Atlantic is taking on the block but the cold will be around for another 10 days to 2 weeks IMO. This will calm things down for a couple of days with very cold nights in particular. More LPs attack from the west towards the end of the month with big signal for significant wind storm for end of the month. The path of this one will determine how first half of Feb pans out.

Just to add even though the jetstream shifts north later in Jan it will still be more south than normal. It may dive well south again for Feb

BFTP

Edited by BLAST FROM THE PAST
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Posted
  • Location: Milltimber, Aberdeen ~ 80m asl
  • Location: Milltimber, Aberdeen ~ 80m asl

Fascinating outputs so far this evening. We are seeing an old school battle for the first time in the internet era and to use a clichéd phrase: ‘The models are struggling’. Well we knew it wouldn’t be easy!

Both the UKMO and GFS seem to suggest the cold air hanging on for longer than this morning. The JMA shows no sign of a warm up all the way out T+192. The Atlantic low comes in and is shunted back by the block, only to come back for a second go that breaks down sending shortwaves underneath the block, followed by signs of pressure building into GL.

There are a number of possibilities and the outcome, as ever, is not very clear. We have all seen how difficult it is to accurately model small areas of low pressure from as little as a few hours away, let alone a few days. The prospect of snow makes this even more tricky as a forecaster.

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Posted
  • Location: sheffield
  • Location: sheffield

No thaw on the latest GFS 12Z run Wayne.

We will have to wait for the other models to come out later, but as I said earlier there is no way that the first Atlantic Low can bring milder air across the UK and on this run, the Atlantic rather calls it a day as High pressure maintains over Norway.

Potentially a serious situation with regard to salt/grit although with more cloud overnight for some areas, at least little in the way of plunging nightime mimima.

Thanks for that, so it looks like we may have the snow laying around a bit then. And with more forecast supposedly bad for round here, the depths may shoot up.:D

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

UKMO 12z 120hr chart

UW120-21.GIF?09-17

Therefore it seems both GFS and UKMO have backtracked from that input of warmer air into the south late next week- UKMO's chart implies that by next Thursday we start picking up some of those colder uppers again in the easterly flow on the northern flank of the low, while high pressure again extends to our N.

Interesting times ahead, that's for sure.

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Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

Let the battle begin. GFS brings the milder further north on the west but quickly loses it and the cold air comes back. After than in deep FI the southerly jet continues to be the boss keeping us on the cool side of things. Going to be very interesting this week.

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

I hope ecm carries on the good work this evening.

Some fellow from the metoffice was on tv earlier saying posible breakdown next weekend!! B)

Saw that. Stressed it was only subtle signs, sounded very uncertain to me and as if in the back of his mind he knew that it could very easily go the other way too

Aaron

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Posted
  • Location: Buxton, Derbyshire 1148ft asl prev County Down, NI
  • Weather Preferences: Winter
  • Location: Buxton, Derbyshire 1148ft asl prev County Down, NI

Ok dates I have posted for bitter cold and heavy snow periods. 3-5, 7-10 and 14-20. One to add and could be heavy snow event for mainly south is 12th.

OK, synoptic outlook that I have on my method. LP attempts inroads on 12th from SW but gets repelled by strong very cold block to NE and slides under. New Moon 14th has done and still signals LPs to attack from the SW. First two will be channel/N France LPs and will slide under the block BUT inroads of slightly less cold air attacks the south but entrenched cold will mean very heavy snowfall potential for southern UK and Ireland. Third one [20th approx] will barrel across heart of the UK and although less cold, very cold air tucks in as N'ly and NE'ly winds come about with building Atlantic Ridge [well north and Scotland could do very well snowise from this one]. So the breakdown is starting inasmuch that the Atlantic is taking on the block but the cold will be around for another 10 days to 2 weeks IMO. This will calm things down for a couple of days with very cold nights in particular. More LPs attack from the west towards the end of the month with big signal for significant wind storm for end of the month. The path of this one will determine how first half of Feb pans out.

BFTP

Blast

Very good summary again !! How do your views correspond with those of GP or Brick for the remainder of Jan and into Feb??

Edited by johnny1972
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Posted
  • Location: Cwmbran. South East Wales 300ft ASL
  • Location: Cwmbran. South East Wales 300ft ASL

All,

Please dont delete this as it is model related in a way because his input his much appreciated by loads. So.....

Where is Mr Steve Murr been through this epic episode??

I have seen him around in only small doses and miss his invaluable knowledge and input.

Come out Steve where ever you are. Your take on the next developments is needed.

WW

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

UKMO at T+144 leaves us in a rather cold no-man's land awaiting Round 2 of the Atlantic attack on our cold continental air:

http://www.wetterzentrale.de/pics/Rukm1441.gif

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Posted
  • Location: Buxton, Derbyshire 1148ft asl prev County Down, NI
  • Weather Preferences: Winter
  • Location: Buxton, Derbyshire 1148ft asl prev County Down, NI

UKMO at T+144 leaves us in a rather cold no-man's land awaiting Round 2 of the Atlantic attack on our cold continental air:

http://www.wetterzen...cs/Rukm1441.gif

TWS

Not for NI, Western Scotland and Ireland - strong southerlies there with no continental influence.

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Guest FireStorm

Ok dates I have posted for bitter cold and heavy snow periods. 3-5, 7-10 and 14-20. One to add and could be heavy snow event for mainly south is 12th.

OK, synoptic outlook that I have on my method. LP attempts inroads on 12th from SW but gets repelled by strong very cold block to NE and slides under. New Moon 14th has done and still signals LPs to attack from the SW. First two will be channel/N France LPs and will slide under the block BUT inroads of slightly less cold air attacks the south but entrenched cold will mean very heavy snowfall potential for southern UK and Ireland. Third one [20th approx] will barrel across heart of the UK and although less cold, very cold air tucks in as N'ly and NE'ly winds come about with building Atlantic Ridge [well north and Scotland could do very well snowise from this one]. So the breakdown is starting inasmuch that the Atlantic is taking on the block but the cold will be around for another 10 days to 2 weeks IMO. This will calm things down for a couple of days with very cold nights in particular. More LPs attack from the west towards the end of the month with big signal for significant wind storm for end of the month. The path of this one will determine how first half of Feb pans out.

Just to add even though the jetstream shifts north later in Jan it will still be more south than normal. It may dive well south again for Feb

BFTP

So all in all, 20th things thaw out before the wind goes back to being N/NE leading to Ice on the thawed surfaces and then a reload situation for the end of the month then?

Edited by FireStorm
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Posted
  • Location: Carmarthenshire - 100M ASL
  • Location: Carmarthenshire - 100M ASL

At this rate the Atlantic low won't bring in any precipitation at all ............ ie if it gets pushed back, run after run.

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