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Model Output Discussion - cold spell to end Autumn


Paul
Message added by Paul

Please only post model discussion in this thread. 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

Thank you!

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

A general summary then: It continues to look as if the jet will be further south and undulating for a period after Thursday. Much colder air than normal will reach the UK at first, and then areas north of this jet may find the cold being locked in. This means the further north you are the greater the chance of staying well below average for several days, with repeating snow episodes. Southern areas will be hoping for the jet to dive further south after the first slider low event if wintry weather is your thing - otherwise, great weather for ducks here.

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Not quite as cold as it will be later this week into next week looking at the short ens but very few members go above 0

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Posted
  • Location: Wirral, Merseyside
  • Weather Preferences: Snow & Thunderstorms
  • Location: Wirral, Merseyside

So pretty good agreement at t96 now with GFS & UKMO

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Snow showers for Scotland, Northern Ireland, Wales, Parts of England through the Cheshire Gap & the fringes of Eastern England. Not to mention more oragnised bands of snow may crop up in the flow.

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It will feel bitter in that wind! :cold:

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Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

Guess we have to start somewhere when looking for our beasterly, uncanny similarities in the extended range between GFS 06z to present 12z I have an inkling the GFS might run with this. 

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Posted
  • Location: Nutts Corner
  • Location: Nutts Corner

If GFS to be believed, Friday could be the start of a really interesting period where just about anywhere could see some of the white stuff over the next week or so.

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11 minutes ago, Dafydd Tomos said:

Same here in Tenby although 10C is possible on Saturday, so much milder than the ensembles show. Well at least apart from a rainy Sunday we should get plenty of winter sunshine :) it's better than mild, wet & windy imo mate

Funny enough I'm back there now! 10C sounds a bit high for Saturday? I've a feeling it'll be colder than that and if the Pembrokeshire Dangler gets going, so might the hail & lightning again like several days ago. If it doesn't, I too would enjoy walking along the coast path in the low, weak winter sunshine  :D

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Full ens generally below average from the next couple of week quite a few members are showing something less cold as we get closer to Christmas

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire
23 minutes ago, Glacier Point said:

Good agreement with the GWO in the coming 10-12 days.

As a proxy for angular momentum, MJO heading towards phase 7 suggests falling momentum tendency, phase 8 GWO.

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Need to tweak these composites for more amplified longwave pattern and strong -AO, but in essence support for mid Atlantic ridge to continue.

Key to next synoptic evolution will be either a seasonally induced change on wavelength, and / or MJO / Convective wave heading back through phase 3-4-5-6. Usually a 30-45 day cycle, so that again puts us into early stages of Jan.

Thank you GP. Have you any thoughts on what lay in store over the festive period?

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Posted
  • Location: Swansea South West Wales
  • Weather Preferences: Cold and Snow in winter Warm Sunny Summer
  • Location: Swansea South West Wales

From what I can remember with the last slider situation we had in January 2013 the fronts from that hit started off as rain then turned to snow with uppers only around -2. The thing was it was pulling air in from France so the dew points were below freezing also. Looking at this chart it could well be a similar set up and so you won't need uppers of -6-7 just need the few points to be dragged down ahead of the front so this could be a snow fest for more southerners too not just the usual north of M4 folk.

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6 minutes ago, Draig Goch said:

Funny enough I'm back there now! 10C sounds a bit high for Saturday? I've a feeling it'll be colder than that and if the Pembrokeshire Dangler gets going, so might the hail & lightning again like several days ago. If it doesn't, I too would enjoy walking along the coast path in the low, weak winter sunshine  :D

This is the day in question; Sunday. 

Low pressure system passing right over Ireland and SW UK looks like it could bring snow over the hills but not on the coast. Both of those charts would have the wind blowing off a relatively mild Bristol Channel for here anyway so maybe not snow but there could be some more thunder & lightning around the coast as the cold, unstable air combines with mild, moist sea air I'd have thought?  

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Posted
  • Location: South Manchester
  • Location: South Manchester

Interesting output, curious on the below on Monday

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Still a bit concerned about this all (snow wise IMBY). We were all set for a pasting this Wednesday IIRC on *that* GFS run, nice amount of back edge snow, this then slipped to the end of the week, then the PPN vanished then the old phrases "get the cold in first" got rolled out - then the tease comes back in with the above on Mon - always just outside the reliable. Looking forward to the cold, but we're probably the wrong side of marginal for snow - things need to be perfect.

Comparing 06z to 12z, the events on Sun>Mon seem to have caused the ensembles to diverge quite a bit run to run

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(I still like the old format)

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Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire

That'll do, 

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I mused yesterday we may well see a combination of Euros vs GFS with regard to the 'initial' slider, and today UKMO and GFS have moved toward each other coming up with a nice combination of yesterday's 12zs.

slider low moving into the established northerly flow resulting in frontal snowfall somewhere on its north eastern edge, placement will change but tonight's runs are peachy Imby

overall, and beyond, we look to be in a situation where this could well be the first of many snowfall possibilities right across the country from various directions/sources.

game on for winter proper :):):)

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Posted
  • Location: CARDIFF
  • Location: CARDIFF
29 minutes ago, Glacier Point said:

Good agreement with the GWO in the coming 10-12 days.

As a proxy for angular momentum, MJO heading towards phase 7 suggests falling momentum tendency, phase 8 GWO.

ECMF_phase_MANOM_51m_full.thumb.gif.bb3f16ff29ebf66341c09a371507b9c5.gif5a25852c54f65_gwophase8decfilternina.thumb.jpg.7501b5d7efa0c249433882abb9734403.jpg

Need to tweak these composites for more amplified longwave pattern and strong -AO, but in essence support for mid Atlantic ridge to continue.

Key to next synoptic evolution will be either a seasonally induced change on wavelength, and / or MJO / Convective wave heading back through phase 3-4-5-6. Usually a 30-45 day cycle, so that again puts us into early stages of Jan.

 

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Posted
  • Location: Hampstead / Cambridge
  • Location: Hampstead / Cambridge
5 minutes ago, Stephen_Mcr said:

Interesting output, curious on the below on Monday

prectypeuktopo.thumb.png.3973b22ea7276f56756924e1e389f329.pngh500slp.thumb.png.c8cf849607f399e5692ee05ba59dbed5.png

Still a bit concerned about this all (snow wise IMBY). We were all set for a pasting this Wednesday IIRC on *that* GFS run, nice amount of back edge snow, this then slipped to the end of the week, then the PPN vanished then the old phrases "get the cold in first" got rolled out - then the tease comes back in with the above on Mon - always just outside the reliable. Looking forward to the cold, but we're probably the wrong side of marginal for snow - things need to be perfect.

Comparing 06z to 12z, the events on Sun>Mon seem to have caused the ensembles to diverge quite a bit run to run

MT8_Manchester_ens.thumb.png.1ce7c19d503032dec76a76015bd81618.pngMT8_Manchester_ens2.thumb.png.0c6b53e5a0baa4ac6add2d3bc2701f44.png

(I still like the old format)

Much flatter on the 12Z...

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Posted
  • Location: Orpington Kent
  • Weather Preferences: Snow freezing rain heat waves
  • Location: Orpington Kent

Folks in the south east England will be very happy with this chart I no it’s a long way out but you never no. That  would bring heavy snow and freezing winds from the east.:cold:

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Posted
  • Location: Walsall, West Midlands 135m/442ft ASL
  • Weather Preferences: Heatwaves, thunderstorms, cold/snowy spells.
  • Location: Walsall, West Midlands 135m/442ft ASL

These charts just show how snowy it could become across parts of the country by the end of the weekend, and could even be more than what these are showing now as other features could pop of unexpectedly. 

Also how cold it is going to become.

Last couple of charts is showing the potential beast from the east in FI.

Amazing charts for us coldies , best for years, hoping the later charts verify to take on or even beat the cold spell what we all remember well 7 years ago :)

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Posted
  • Location: CARDIFF
  • Location: CARDIFF

You are the expert along with Tamara on MJO but i find phase 7 is one of the best phases for cold weather across Western Europe and the prediction is for possible strong phase 7 by around 13th December and that takes us to a very interesting period from 26th December onwards.

Along with the cold spell from Thursday this week things are looking a lot more interesting than they have for the previous few years. Sliding lows will make the difference locally but the main thing is to get the main drivers playing ball and getting cold in place. When this happens opportunities arrive .

Glacier - please let me know if you do not see phase 7 as being good, as although its what i find, i am still learning the technical drivers

 

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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

A delightful GEFS 12z mean showing prolonged cold with scandi trough and mid atlantic ridge with an on-going chance of snow / wintry ppn and widespread frosts for much of the uk.:)

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Edited by Frosty.
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3 minutes ago, Dafydd Tomos said:

This is the day in question; Sunday. 

Low pressure system passing right over Ireland and SW UK looks like it could bring snow over the hills but not on the coast. Both of those charts would have the wind blowing off a relatively mild Bristol Channel for here anyway so maybe not snow but there could be some more thunder & lightning around the coast as the cold, unstable air combines with mild, moist sea air I'd have thought?  

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Yes indeed, early days but if these charts verify Sunday morning but more especially next Monday evening could be quite lively lightning-wise through the channel!! Although the strongest winds would've cleared south we'd be left with a W or WNW breeze. Have you seen a Lift index of 23 across us before? 

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