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Model output discussion - The run up to Christmas


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Posted
  • Location: Exile from Argyll
  • Location: Exile from Argyll
4 minutes ago, Weathizard said:

It’s my one criticism of Meteociel is that they don’t have a side by side comparison viewer like the netweather GFS charts does.

Meteociel has a whole panel of charts to compare, you just need to click on voir panel multimodeles.

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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
3 minutes ago, Downburst said:

I’ll probably be banned and warned by a mod, but never mind. This winter the northern hemisphere view is very prevalent on the board. And why not with such a blocked Atlantic. But for heavens sake, there is precious little actual cold developing at all. Today is colder synoptically then most of FI. This is getting crazy. Let’s get it together and be a little more tactical in analysing just exactly what we truly believe may happen in the British isles. I want snow as much as anyone, but a lot of toppers deliver more. This low is not cold enough, it doesn’t have a cold source and that’s a fact.

 

 

The 500hPa pattern is crucial and that is where the excitement lies. Without this we will not have any chance of delivering cold enough air to our shores. The cold air is there up north but the release hasn’t been nirvana like. Yet...

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Posted
  • Location: Liphook
  • Location: Liphook
4 minutes ago, chionomaniac said:

Yep block has been too far north and west last run. So slightly more east and south better for us

Yes definately looking better out to 192hrs, also a slightly better looking tilt as well to the upper high that exerts more SE pressure upon the LP that is heading towards us.

Weaker, but better placed.

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Posted
  • Location: St Austell,Cornwall
  • Location: St Austell,Cornwall
1 minute ago, kold weather said:

Yes definately looking better out to 192hrs, also a slightly better looking tilt as well to the upper high that exerts more SE pressure upon the LP that is heading towards us.

Weaker, but better placed.

So really we don't want to have this further east then already it is then?

We are still some time away so I fear that may be the case but hopefully I'm wrong 

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Posted
  • Location: Liphook
  • Location: Liphook
7 minutes ago, Downburst said:

I’ll probably be banned and warned by a mod, but never mind. This winter the northern hemisphere view is very prevalent on the board. And why not with such a blocked Atlantic. But for heavens sake, there is precious little actual cold developing at all. Today is colder synoptically then most of FI. This is getting crazy. Let’s get it together and be a little more tactical in analysing just exactly what we truly believe may happen in the British isles. I want snow as much as anyone, but a lot of toppers deliver more. This low is not cold enough, it doesn’t have a cold source and that’s a fact.

 

 

I'll wager you might end up being quite surprised just how much snow we will wrangle out of set-up like the one we are seeing from the 28-29th.

Alot will depend on LP/frontal placement, but somewhere could get lucky if it sets up well and does a small cyclonic loop around the bigger LP flow. If that happens somewhere will end up with 15-20cms. It won't be a large area of snow, but could be quite decent fall if we get lucky.

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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

Far bigger cold pool to the east of Greenland. Just need it to hit us...

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

Busy run up to christmas time, so struggling to really digest the models: In the immediate our coldest christmas eve-christmas day combination since 2010, I said yesterday how mild recent years have been since then.. lots of frost and chance of wintry showers for some, possible snowflakes if your lucky. Boxing Day sees a change in fortune, milder conditions briefly with heavy rain and gales..

The major change comes 27 December onwards, and this change has been remarkably well forecast by GFS, with heights advecting to Greenland and a deep longwave cold trough anchoring down through the UK. What happens on the surface very tricky to call, its a messy situation, sudden trough formation will most likely develop. Hard to call just where snow might fall, but I will stick my neck out and say it will fall at low levels.

Longer term, signs the low will move SE and usher in a cold N/NE feed with heights remaining high to our NW, possibility of further low pressure/trough features moving down in the cold N flow, could be in slider territory and with a cold pool, less marginality would most likely guarantee snow at low levels. 

I'll be taking a glancing look time to time at the models over the next 3 festive days but no posts, time for other things, come Sunday the prospects for start of New Year will be in the reliable and for the first time since 2009 these based on current models suggest the direction is only of a cold persuasion possibly very cold!

Happy Christmas!

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Posted
  • Location: South Oxfordshire
  • Location: South Oxfordshire
Just now, chionomaniac said:

Far bigger cold pool to the east of Greenland. Just need it to hit us...

Will it be A or B or neither? 

Looks ghoulish  

gfsnh-1-222 (1).png

gfsnh-1-222 (1)__01.png

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Posted
  • Location: Liphook
  • Location: Liphook
3 minutes ago, Skullzrulerz said:

So really we don't want to have this further east then already it is then?

We are still some time away so I fear that may be the case but hopefully I'm wrong 

We will have to wait and see.

The evolution out to 225hrs though is very different from any of the GFS runs today thus far which have all followed a broadly similar pattern. i'm curious where it will end up as there is alot more energy riding up the western side of the ridging. May end up with a HP much closer to our shores instead this run. We will see. 

Still looks good btw, just different.

Edited by kold weather
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Posted
  • Location: Cardiff
  • Weather Preferences: Day 10
  • Location: Cardiff
21 minutes ago, Tanden Sparkster said:
synoptic-charts.jpg
WWW.METOFFICE.GOV.UK

Find out what the lines, arrows and letters mean on synoptic weather charts.

 

Thanks, what about the 850s and 500s which most seem to use here.  

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Posted
  • Location: Shanklin, isle of wight
  • Weather Preferences: Snow,snow and more snow
  • Location: Shanklin, isle of wight
11 minutes ago, Downburst said:

I’ll probably be banned and warned by a mod, but never mind. This winter the northern hemisphere view is very prevalent on the board. And why not with such a blocked Atlantic. But for heavens sake, there is precious little actual cold developing at all. Today is colder synoptically then most of FI. This is getting crazy. Let’s get it together and be a little more tactical in analysing just exactly what we truly believe may happen in the British isles. I want snow as much as anyone, but a lot of toppers deliver more. This low is not cold enough, it doesn’t have a cold source and that’s a fact.

 

 

Please not the uppers scenario again

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
2 minutes ago, chionomaniac said:

Far bigger cold pool to the east of Greenland. Just need it to hit us...

I am looking east Ed☺️

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Posted
  • Location: st albans
  • Location: st albans
1 minute ago, kold weather said:

We will have to wait and see.

The evolution out to 225hrs though is very different from any of the GFS runs today thus far which have all followed a broadly similar pattern. i'm curious where it will end up as there is alot more energy riding up the western side of the ridging. May end up with a HP much closer to our shores instead this run. We will see. 

Still looks good btw, just different.

No neg wnao on this run Kold ! 

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Posted
  • Location: Liphook
  • Location: Liphook
2 minutes ago, chionomaniac said:

Far bigger cold pool to the east of Greenland. Just need it to hit us...

I don't want to jinx it because the GFS will find a way, but I can't see any realisitic way from 228hrs position that we can avoid getting that cold air right over our shores.

Biggest risk his run is it just topples down towards us. In itself that may still end up being usable if the upstream pattern works in our favour.

Quite the difference though from previous runs. Shows there is alot of uncertainty with this pattern still.

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

Big change at D10 on this run. Much flatter upstream...lost the amplification. Could possibly end with Atlantic HP pushed SE with the jet over the top.

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Posted
  • Location: blackburn
  • Weather Preferences: heavy snow/ heatwaves
  • Location: blackburn
56 minutes ago, Mike Poole said:

No GloSea5 or MOGREPS aren’t showing anything different, I’ll bet my car!  They are deliberately downplaying it in my opinion probably for Covid, Brexit, panic buying reasons - see MO updates thread, not wanting to derail this thread.  

31221684-C676-4087-8B8D-080A0A4C5050.png

Edit no idea why the T6 chart is there, but merry Christmas everyone anyway...❄️

Careful. I got slaughtered earlier for saying exactly this. 

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Posted
  • Location: North London
  • Location: North London
Just now, CreweCold said:

Big change at D10 on this run. Much flatter upstream...lost the amplification. Could possibly end with Atlantic HP pushed SE with the jet over the top.

Yeah definitely looks like the ridge is collapsing 

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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
1 minute ago, iowpompeylee said:

Please not the uppers scenario again

I don’t think the question about 850’s is a bad one. It is what keeps it on such a knife edge. Over -8°c probably guaranteed snow, lower than that then it is a wheel of fortune

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Posted
  • Location: South Oxfordshire
  • Location: South Oxfordshire
2 minutes ago, Allseasons-si said:

I am looking east Ed☺️

Good call, mostly option B but both seem to be converging too a degree too

 

gfsnh-1-246 (1).png

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Posted
  • Location: Neath Valleys, South Wales 109m asl
  • Location: Neath Valleys, South Wales 109m asl
1 minute ago, CreweCold said:

Big change at D10 on this run. Much flatter upstream...lost the amplification. Could possibly end with Atlantic HP pushed SE with the jet over the top.

Not on this one crewe... 

To much low pressure under the block and not enough forcing from the jet.

Cut off heights around griceland maybe... 

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.

Seems to be a choice here, either have a big stable proper Greenland block but with more risk of a West based NAO which could mean little or no snow initially but could bare more long lasting fruit, or have fingers and wedges that are more susceptible to collapse but somewhere could hit the  Jackpot middle of next week.

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Posted
  • Location: Liphook
  • Location: Liphook
4 minutes ago, bluearmy said:

No neg wnao on this run Kold ! 

No, and to be fair this solution was present on the 12z GFS ensembles as well so its not exactly come out of nowhere. The control run for example had something not too different from it. Still was a decent run that time as well.

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