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Model thread discussion - cold spell looming


Paul
Message added by Paul,

It's busy right now, so please ensure you only post about the model output in this thread. 
For local snow discussion and will it snow posts, please use the regional threads
And for more general chat please use the chat, moans and ramps thread.
There's now also a cold spell chat and discusison thread.

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

The UKMO continues to want to lift out all the surface cold by day 6 . Once again the most progressive with that .

Earlier at day 4 it has a small kink in the flow towards the sw suggestive of a front moving in and that marks the boundary between the different air masses .

Judging by the 850 values , we can see the progression of the front is quite slow , it seems to move ne slowly , the cold air hangs on for dear life in the far east and se until Sunday .

Hard to judge how active any front will be this far out but still the chance even with the grinch model of some snow during the change over .

The set up is complex and messy across the other outputs aswell . 

 

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Posted
  • Location: West/East/Sussex Surrey border
  • Location: West/East/Sussex Surrey border
20 minutes ago, Tim Bland said:

One word.. Sun.   Yesterday it was snowing moderately, -8 uppers, -2c air temp, -4 DP and sun 528 Dam thickness. Despite all of this the snow was melting quicker than it was falling. If you looked at the sun you could just about make it out behind the clouds so the light was enough to warm the black pavements etc.  Today was sub zero with below zero DP but one sunny spell and all the snow has gone. It’s approaching mid feb so it takes something very special to deliver long lasting snow. Unfortunately no models are showing this now. Perhaps as GFS shows we can get one last proper snow fall in Sunday or Monday (icon also does Amy his further west on Sat) but no model shows anything near to what is needed for a proper snowy spell in mid Feb. 

21FBFE1F-4C82-4155-8954-E710207BFC1B.png

50D3D403-D6D3-4218-B4ED-FC14005EB51B.jpeg

The 80’s were full of glorious long snowy periods with snow settled for days on end. Don’t think sun is an issue

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
27 minutes ago, phil nw. said:

Well really by day 6 it looks a bit of a stalemate.Both gfs/ukmp show the block is not giving enough to let the Atlantic right into the UK.

It is more than likely the west will see something milder at least for a spell but a look at the gfs jet pattern at t144 shows the difficulty modeling is having in calculating the pathway forward.

gfsnh-5-144.thumb.png.ec672b31ae60660b74224c8d7d0dd0b2.png

The northern arm of the jet has no coherent pathway but does limited resistance to the ridge getting further north.The main energy in the jet is still running south so that Atlantic push remains quite indecisive up to there.

Have Meteociel changed that jet stream chart, I don’t recall seeing all that purple before?  Not sure if that is an improvement or not, don’t like change!

Looking at the models over the last few days, I do not see a return to mild, we’ve been here before a few days ago, and it got pushed back.  I think it will again.  What is becoming the issue, though, is where we get the major snow dumping from, some kind of battleground scenario, or channel low would be good, but not seeing either on the models at the moment.

 

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Posted
  • Location: Maldon, Essex
  • Location: Maldon, Essex
2 minutes ago, steveinsussex said:

The 80’s were full of glorious long snowy periods with snow settled for days on end. Don’t think sun is an issue

The continent is covered in snow - and many places have a more southerly latitude.

More to do with the lack of anything heavy.

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Posted
  • Location: Dipton, Nr Consett, Co.Durham, 250m, 777ft asl
  • Weather Preferences: Anything but boringly hot
  • Location: Dipton, Nr Consett, Co.Durham, 250m, 777ft asl
9 minutes ago, Mike Poole said:

Have Meteociel changed that jet stream chart, I don’t recall seeing all that purple before?  Not sure if that is an improvement or not, don’t like change!

Looking at the models over the last few days, I do not see a return to mild, we’ve been here before a few days ago, and it got pushed back.  I think it will again.  What is becoming the issue, though, is where we get the major snow dumping from, some kind of battleground scenario, or channel low would be good, but not seeing either on the models at the moment.

 

Yep, the models have eeked out an extra 4 days of cold, so in that respect I would place FI at t96

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As we discussed earlier, I think we need to get to as late as Thursday or Friday before confidence builds regarding next week. Who remembers the 80’s when cold air masses would win out against all expectations (even from senior forecasters). Though, probability wise it is more than likely the end of the road for this short spell of wintry weather.

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

I think there’s enough in the other models to call into question the UKMOs bullishness about removing the surface cold so quickly .

I’ll leave it to the ECM to cast the deciding vote .

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Posted
  • Location: South Essex
  • Location: South Essex

From looking at the GEFS (snapshot at 168 hours) you would have to say its looking more like a mid lat Euro high now than a genuine Scandi High. That said, there is still just enough doubt in this set to leave it until the morning to call a definitive 'game over'.  Normally I'd be throwing the towel in now but I just look through the output and still have a slight doubt in my mind. Maybe wishful thinking though. 

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Posted
  • Location: Dipton, Nr Consett, Co.Durham, 250m, 777ft asl
  • Weather Preferences: Anything but boringly hot
  • Location: Dipton, Nr Consett, Co.Durham, 250m, 777ft asl
10 minutes ago, Tim Bland said:

By the middle of next week there are 3 cold runs , which is less than 10%...

3AB651CC-708E-4C84-87D4-D2AE3AAFD3DA.png

0FB64D2C-AA78-4DC2-8B68-3768257277C2.png

Shows a dry set up until 15th, that's about 4 extra days as was showing before this cold spell started.

I certainly wouldn't rule out changes or an extension to the cold set up, not when there's so much to be resolved when the high starts to form 

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Posted
  • Location: pelsall, 500ft asl (west mids)
  • Location: pelsall, 500ft asl (west mids)
49 minutes ago, Tim Bland said:

One word.. Sun.   Yesterday it was snowing moderately, -8 uppers, -2c air temp, -4 DP and sun 528 Dam thickness. Despite all of this the snow was melting quicker than it was falling. If you looked at the sun you could just about make it out behind the clouds so the light was enough to warm the black pavements etc.  Today was sub zero with below zero DP but one sunny spell and all the snow has gone. It’s approaching mid feb so it takes something very special to deliver long lasting snow. Unfortunately no models are showing this now. Perhaps as GFS shows we can get one last proper snow fall in Sunday or Monday (icon also does Amy his further west on Sat) but no model shows anything near to what is needed for a proper snowy spell in mid Feb. 

21FBFE1F-4C82-4155-8954-E710207BFC1B.png

50D3D403-D6D3-4218-B4ED-FC14005EB51B.jpeg

Agree 

but surely late March 2013 shows how possible it is to get days and weeks of lying snow even in spring ❄️

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .
Just now, sheikhy said:

Hmmm gefs look an upgrade!!theres a siginificant amount that are colder!!!!thought they would look much worse!!!

Yes you and me both ! If only that damn UKMO output would stop being so miserable! 

Because of the entrenched cold over Northern Europe and snow cover and the UKs own cold bubble the 850 values aren’t so important in terms of delivering frontal  snow .

 

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Posted
  • Location: sunny sunny Bournemouth
  • Weather Preferences: Winter: Bartlett style mild and benign
  • Location: sunny sunny Bournemouth
50 minutes ago, James Maidstone said:

I think there is other stuff coming into play here such as:

- the underlying warmth of the ground from last week which is still not that cold

- solar heating in the day from when the clouds clear in the afternoon.  I think even under colder uppers such as minus 20 you can still get partial melting in the day due to solar activity.   Someone please correct me if I am wrong?

We had a dusting today. Where I work, the dusting just disappeared yet no sign of melting.

Google "sublimation"......

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Posted
  • Location: Hull
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Hull

Looking at the latest model output, I think we will see a gradual transition to milder weather next week. Whether there will be some snow for that breakdown and how quick that transition to mild will be are the two big questions for the moment.

Imagine if the EC Op followed P20 though this evening. If we shout P20 enough times it may actually happen.

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

Evening all - certainly looks like that High Pressure will struggle to stay north without a little more disruption underneath. But then again, we've seen considerable changes in disruption at very short timescales this winter. Even if the first attempt fails, there's still a chance the second will succeed.

Snowy breakdowns though look like missing us on UKMO though.

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Posted
  • Location: Cardiff, Wales
  • Weather Preferences: Snow, Thunder & Lightning, Thundersnow, Storms, Heatwave
  • Location: Cardiff, Wales
10 minutes ago, Battleground Snow said:

Yes a couple more have joined the colder cluster at 144, the OP one of the milder options in the pack.

gfs-london-gb-515n-0e (1) (20).jpeg

Yep, Theta E values also reinforcing the slight swing back. Good clustering keeping these below 10c until 15th Feb compared to 00z and 06z set. Would need to see this continue on upcoming GEFS runs and also the EC Ens to show a similar swing back colder. Better than where we were after the 00z runs anyway!

graphe5_0000___-0.12574_51.5085_Londres-2.gif

graphe5_0000___-0.12574_51.5085_Londres.gif

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Posted
  • Location: STEVENAGE, HERTS (100M ASL)
  • Location: STEVENAGE, HERTS (100M ASL)
23 minutes ago, nick sussex said:

I’m actually surprised how good the GEFS are in terms of synoptics rather than upper level cold considering the trend since yesterday . In terms of 850 values yes not many deep cold runs but quite a few keep the surface cold and   an upgrade in cold in terms of 2 m temps . I’m suddenly a bit more interested in the ECM run and what that delivers .

Depends what you are looking for I suppose, surface cold is not enough to even keep the snow people have with the warm ground temps and increasing sun strength. I’d take clear and sunny though, anything other than barreling lows with cold rain! I’m hoping the ECM keeps the dream alive for a snowy breakdown. I’d like to see the first Atlantic push make it as far as my back yard then stall ...but that’s being very selfish lol 

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .
1 minute ago, Man Without Beard said:

Evening all - certainly looks like that High Pressure will struggle to stay north without a little more disruption underneath. But then again, we've seen considerable changes in disruption at very short timescales this winter. Even if the first attempt fails, there's still a chance the second will succeed.

Snowy breakdowns though look like missing us on UKMO though.

I think there’s one front on Saturday judging by the day 4 chart but not sure how potent that will be this far out .

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