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Model output discussion - mid-winter


Paul
Message added by Paul

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Posted
  • Location: HILL OF TARA IRELAND
  • Weather Preferences: SNOW ICE
  • Location: HILL OF TARA IRELAND
1 minute ago, Frosty. said:

The Gfs 6z screams wintry potential next week, turning much colder from early next week as we import an air mass with origins in Greenland / Northern Canada..plenty of increasingly squally wintry showers, turning more to snow..I have to say next week is looking more white than wet to me with even a spell of heavy persistent snow on the 6z later next week..:cold::D  

Yes it seems to be getting better with each run we might have to go to the ramp thread:cold:

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Posted
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
  • Weather Preferences: Northeasterly Blizzard and sub zero temperatures.
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
3 hours ago, carinthian said:

Morning all, GFS ends with winter dream charts which looks a reasonable outcome to me. However, in the medium term there seems a variance to the flow profile at 144t between the UK/ECM run and the GFS. The chart below shows a more westerly flow at that stage . ThIs 500mb pressure /temp profile chart from UKMO at 144t highlights a tightening pressure and upper air temperature gradient to the southwest and what looks like a wave formation to develop. So not that straight forward to cold into Southern Britain as the south /SW  could yet be in line for some very stormy weather by the end of next week. Longer term looks cold for all with snow in favoured locations as Polar Continent air mixes in with the unstable Pm flow. Looks very interesting weather next week that should keep many cold fans interested in developments. Will get back this afternoon with a report from our Portal weather Service providers, specifics regarding UK next week.

C

U144-21UK.gif

Latest GFS run now develops a wave /depression to run across Southern Britain at 138t. That will be interesting if that track holds with snow for parts of the Midlands. Looking at the 300mb jet flow , its postion looks about right and will coincide with earlier UKMO run also with their extended N .Atlantic charts. Could be some nasty winds in its wake around Southern England.

C

GFSOPEU06_138_1.png

Edited by carinthian
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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

Face value from the 06z GFS for the secondary low running across the south on Wednesday - looks like wrong side  of marginal south of a line from Mersey to Wash, based on 0C dew point line. The low's just too deep as it crosses UK and pulls in milder air in circulation, needs to be a shallow wave. Anyway, likely not appear or appear as deep or different track/timing on subsequent runs, so not worth getting too hung up about.

slp_w21z.thumb.png.22e2a64f705bf4aa924a3cc5c4cbbfc8.png

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Posted
  • Location: oldham
  • Location: oldham
1 minute ago, bluearmy said:

At the risk of being lambasted for not seeing a wintry nirvana next week (runners aside which has always been the caveat), I’m still struggling to see where sustained snow cover is likely away from elevation with an onshore flow. 

At the risk of being a little silly where are the post showing low level on shore snow cover?

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Posted
  • Location: Kings Norton, West Midlands
  • Weather Preferences: Thunderstorms, Cold & Snowy
  • Location: Kings Norton, West Midlands

A rather hidden feature I've not noticed in meteociel is the ability to scroll through the different runs (00z,06z,12z,18z) for each time e.g. 112h, 118h etc.). This can be done if you have a mouse with a scroll wheel and hovering over the actual time you want to analyse. Pretty cool if you haven't noticed it already. 

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Posted
  • Location: Somerset.
  • Location: Somerset.
9 minutes ago, MR EXTREMES said:

Well that's just the outlook from data collected yesterday.

But I'd be interested in seeing the charts to support this.

And from what the models are showing is worth hyping considering its from a polar source.

From there it's anyone guess and no BBC forecaster with go much further than five days.

Forecasting is complicated at the best of times, but rather than go all in, they try to keep forecasting as accurate as possible.

So saying it's going to be blizzard conditions when there's possiblity it might not happen is just second guessing but if there's enough support then forecasts will reflect this.

So as I've suggested the models are a tool to help human input for actual weather outcomes.

So if we took your post as gospel,

then it's possible it could confuse the actual outcome the same goes for any forecaster.

As it stands,

my opinion is a wintry looking outlook,

even if rain and sleet features down here on the sunny Costa south coast.

Yes fair play, i understand and thanks for the explanation. ;)

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

Funny how GFS keeps producing the more complex outcomes for next week with the trough elongating. ECM seems too 'basic' by comparison with it's bloated trough, but that may just be desire-bias talking.

h850t850eu.png h850t850eu.png

The LP by Canada is slower on this run, but more disturbances along the polar jet means the Atlantic ridge is struggling to link up with the Arctic one;

npsh500.png hgt300.png

Could end up with the jet continuing across to the south of the HLB, in which case the Azores High needs to shift far enough west to keep us on the cold side of the polar boundary. Thankfully the jet configuration looks good for this; better than the 00z in fact.

Edited by Singularity
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Posted
  • Location: HILL OF TARA IRELAND
  • Weather Preferences: SNOW ICE
  • Location: HILL OF TARA IRELAND
3 minutes ago, Nick F said:

Face value from the 06z GFS for the secondary low running across the south on Wednesday - looks like wrong side  of marginal south of a line from Mersey to Wash, based on 0C dew point line. The low's just too deep as it crosses UK and pulls in milder air in circulation, needs to be a shallow wave. Anyway, likely not appear or appear as deep or different track/timing on subsequent runs, so not worth getting too hung up about.

slp_w21z.thumb.png.22e2a64f705bf4aa924a3cc5c4cbbfc8.png

Just about to say probably gone by 12z.

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
3 minutes ago, Steve Murr said:

That’s a nice flow developing to the NE

better than the 00z

7E802DAD-2EC5-44F6-9253-8664BA02F9E2.thumb.png.931dd075eaa763dd2474dc9f92f6f14c.png

h850t850eu.png

Low getting deposited a little south of Svalbard again. That area of anomalously ice-free water seems to encourage such things. 

If a sufficient wall of ridging can be constructed to the west of it, though, it can be turned in our favour as a means of driving cold air south. Now how's that for glass half full :D.

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
11 minutes ago, bluearmy said:

 At the risk of being lambasted for not seeing a wintry nirvana next week (runners aside which has always been the caveat), I’m still struggling to see where sustained snow cover is likely away from elevation with an onshore flow. 

Agree, although dew points looks low enough for snow to fall to lower elevations in any showers, the surface temperatures in such a long-track and strong maritime polar flow will be too high to support sustained snow cover away from higher ground or where snow showers are continuous. Would need a low/wave to bring a prolonged fall of snow to lower the ground temps then winds to fall light following the clearance of the low/wave, but that looks unlikely in such a mobile/strong WNW flow. But I think many will see snow falling, but any accumulations temporary and slushy away from high ground.

Edited by Nick F
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Posted
  • Location: North East Cotswolds, 232m, 761feet ASL
  • Location: North East Cotswolds, 232m, 761feet ASL
20 minutes ago, andymusic said:

Thursday - potential for more of us to join the party

gfs-2-138.png?6

That’s a pretty severe snow storm for many....if that happens we are looking at UK a ton standstill 

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Posted
  • Location: Derry
  • Weather Preferences: Snow
  • Location: Derry
10 minutes ago, bluearmy said:

At the risk of being lambasted for not seeing a wintry nirvana next week (runners aside which has always been the caveat), I’m still struggling to see where sustained snow cover is likely away from elevation with an onshore flow. 

Inland areas not have laying snow especially us in Ireland & North West??

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
4 minutes ago, Nick F said:

Agree, although dew points looks low enough for snow to fall to lower elevations in any showers, the surface temperatures in such a long-track and strong maritime polar flow will be to high to support sustained snow cover away from higher ground. Would need a low/wave to bring a prolonged fall of snow to lower the ground temps then winds to fall light following the clearance of the low/wave, but that looks unlikely in such a mobile/strong WNW flow. But I think many will see snow falling, but any accumulations temporary and slushy away from high ground.

What would you class as high ground Nick.. edit looks like meto say 200m ..

Edited by northwestsnow
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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
13 minutes ago, Frosty. said:

The Gfs 6z screams wintry potential next week, turning much colder from early next week as we import an air mass with origins in Greenland / Northern Canada..plenty of increasingly squally wintry showers, turning more to snow..I have to say next week is looking more white than wet to me with even a spell of heavy persistent snow on the 6z later next week..:cold::D  

Just to back up my comments on the 6z regards next week, here are the charts which to me show an impressive cold blast with plenty of potential ❄❄❄❄❄ snow as well as frosts and ice.:cold:

06_108_preciptype.png

06_108_ukthickness850.png

06_108_ukthickness.png

06_138_preciptype.png

06_141_uk2mtmpmin.png

06_141_ukthickness.png

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Posted
  • Location: Pontypridd, Wales 240m asl
  • Location: Pontypridd, Wales 240m asl
3 minutes ago, Thunderywintrysnow said:

Inland areas not have laying snow especially us in Ireland & North West??

Ireland should get pasted in this set up

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Posted
  • Location: Pontypridd, Wales 240m asl
  • Location: Pontypridd, Wales 240m asl
4 minutes ago, Thunderywintrysnow said:

Inland areas not have laying snow especially us in Ireland & North West??

delete - tech isssue

Edited by andymusic
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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
1 minute ago, northwestsnow said:

What would you class as high ground Nick.. 

Over 200m? Just elaborating more on what I included in my last post that those lower level areas where continuous snow showers fall in the WNW flow, i.e. western and northwestern coastal areas, or inland areas affected by streamers such as through central belt of Scotland may see snow accumulate to decent depths due to the temperature kept low by the continuous snowfall.

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Posted
  • Location: South Croydon
  • Location: South Croydon
11 minutes ago, bluearmy said:

At the risk of being lambasted for not seeing a wintry nirvana next week (runners aside which has always been the caveat), I’m still struggling to see where sustained snow cover is likely away from elevation with an onshore flow. 

I've got to agree.  Looking at it the surface temperatures look too high on Monday for most areas (seems to be around 5c).  At the moment to me, it really looks like elevation is needed, even in the North.  Snow chances do look to increase as the week progresses but with the flows direction, it all still remains highly marginal away from high ground.  As for the south I really can't see anything other than sleet next week.  I do hope I'm wrong and those 850's dip a little further to get the right side of marginal for more widespread areas.

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Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL

there's an echo in here today :rofl:

That runner that develops and crosses the UK at around +126 would be rain for most imo. But it is a long way out, could miss the UK altogether or disappear on the next run (less likely).

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