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Model output discussion - Winter approaches


Paul

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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield
9 minutes ago, Geordiesnow said:

I think its fair to say in this instance, it was not a true ridge(e g thicknesses were never in the yellow category) so it's one of those where it could easily collapse which will have consequences downstream for us. As I said last night, if the ridging is weaker than first thought, the outlook will very quickly turn flat with the Atlantic weather coming back into play. 

However we have seen much stronger ridges collapsing because of shortwaves and there is no doubt a true Atlantic ridge which does not collapse within 24 hours is getting rarer and rarer hence true Northerlies are also getting more rare by the decade. Maybe the jet stream is stronger these days due to warmer air getting warmer so the contrast between the cold air and warm is larger these days than it used to be but who knows. 

Let's not forget though, a model outlook can quickly change to favour cold again so never give up hope. 

Thanks. Great points but my main point is why can't any Heighths leave the USA and Canada and form a block over greenland and Northern Atlantic. Riding from the azores to greenland occurs during a big neg nao. Sorry if I digress 

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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
  • The first of hopefully many arctic plunges during the days, weeks & months ahead...yeah the gloves are off..I’m a coldie dammit!!!!..
  •  ❄️

  •  

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A68C3A7F-CD39-48DA-BF42-1B4DB74C5FC9.jpeg

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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield

So before the 12z start who's thinking scan block with jet moving sse?? I'm not expecting a big change but could it given previous runs

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Posted
  • Location: North West
  • Weather Preferences: Anything but the prevailing wind!
  • Location: North West
1 minute ago, booferking said:

12z begin Icon more blocked.

iconnh-0-180 (1).png

Yep and this is the bifurcation point now. The cold spell Saturday went kaput days ago now but the path of the next low is up for grabs.

image.thumb.png.4c899e096cd8c5f39439107db84a58cc.png

Less spacing between the two lows on the GFS 6z and the amplification is weaker and too far East. There were certainly more 6z GEFS members which went for this but it’s 50/50. Similar on the EPS clusters. On the other hand there are plenty of  runs which have barely any spacing and thus there is minimal amplification. The 0z GFS para highlights this:

image.thumb.png.032242b70e5cd2b3947e29fa83b34e61.png
With the result being

image.thumb.png.69fe16571d7fdb7e28098246a49fa518.png
Long fetch southwesterlies. The pest from the West. 

As long as that’s on the table It’ll be an anxious watching brief over the coming days...

image.png

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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield

Looking at the 12z gfs our attempt looks a bit frail. Look east to the urals and russiamega ridge even for there. Get that in place and maybe the jet will be in a Southern downward spiral

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Posted
  • Location: South Oxfordshire
  • Location: South Oxfordshire
7 minutes ago, swfc said:

Looking at the 12z gfs our attempt looks a bit frail. Look east to the urals and russiamega ridge even for there. Get that in place and maybe the jet will be in a Southern downward spiral

Hints over the Atlantic too

Looks more amplified ?‍♂️ 

gfsnh-0-162 (1).png

gfsnh-0-186.png

Edited by Griff
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Posted
  • Location: Tyrone
  • Location: Tyrone
2 minutes ago, swfc said:

Looking at the 12z gfs our attempt looks a bit frail. Look east to the urals and russiamega ridge even for there. Get that in place and maybe the jet will be in a Southern downward spiral

Gfs always over does the PV nice spilt in PV  showing up @144hr ukmo

gfsnh-0-144 (3).png

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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)

The UKMO has a Pacific ridge into the pole,it's not there on the gfs

both at 144hrs

UN144-21.thumb.gif.fa44291726d428e699ebb1f1bcc4f16c.gifgfsnh-0-144.thumb.png.289208fe59c0e371f27f14780aae1224.png

 what implications would this have down the line i wonder.

Edit: just seen @booferking's post above^

Edited by Allseasons-si
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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)

Ridge going up further west and earlier on the latest 12z gfs

12z 198 v's 06z 204

gfsnh-0-198.thumb.png.c7916952bbf75bf2cc9d0a59acbb385d.pnggfsnh-0-204.thumb.png.057f5e21e46ef172d381ba40ddd800b1.png

could be a good run this.

 

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Posted
  • Location: South Oxfordshire
  • Location: South Oxfordshire
4 minutes ago, nick sussex said:

Much better upstream pattern on the GFS 12 hrs run at day 8 with more amplification .

Downstream this would help to drag high pressure further north over the UK.

You’d need though even more amplification to sharpen up the troughing to the west of the UK to help get the loop back in the jet sw towards the Low Countries to support the high getting into a more favourable position for cold.

Anyway it’s a start at least after the mornings outputs.

Agreed re amplification, short term this keeps us mild, so presumably the pay off is disruption to PV / lack of raging westerlies and perhaps opportunity for heights later to the north?  

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Posted
  • Location: Morecambe
  • Location: Morecambe
13 minutes ago, Allseasons-si said:

The UKMO has a Pacific ridge into the pole,it's not there on the gfs

both at 144hrs

UN144-21.thumb.gif.fa44291726d428e699ebb1f1bcc4f16c.gifgfsnh-0-144.thumb.png.289208fe59c0e371f27f14780aae1224.png

 what implications would this have down the line i wonder.

Edit: just seen @booferking's post above^

I think excitement over a Pacific ridge into the Arctic is misguided, I have not seen a cold spell happening for us via a Pacific ridge as this just sends cold air through America and out into the Atlantic which means a powerful jet stream for us. We need too see WAA heading up to the pole via a high pressure cell before we can get excited about a cold spell. 

Anyways after a brief waveyness in the jet stream, for us it's looking like mild weather will quickly return. The next few days are going to be warm for some. A record breaking warm November is looking more and more likely. 

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .
3 minutes ago, Griff said:

Agreed re amplification, short term this keeps us mild, so presumably the pay off is disruption to PV / lack of raging westerlies and perhaps opportunity for heights later to the north?  

Given the time of year any flow off the continent together with a possible inversion could get temps down .

In terms of heights to the north it looks a hard slog at the moment , I think any heights if they do occur will be more likely towards the east ne given where the PV wants to set up .

This new amplification has just shown up , it might be another false dawn but if we could squeeze a bit more out of that then it could turn colder for a time.

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

Pretty underwhelming 12z runs so far. Looks like patience will be a virtue as always! We’re still a few weeks from the winter sweet spot of potential cold combined with short days anyway.

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Posted
  • Location: South Oxfordshire
  • Location: South Oxfordshire
1 minute ago, nick sussex said:

Given the time of year any flow off the continent together with a possible inversion could get temps down .

In terms of heights to the north it looks a hard slog at the moment , I think any heights if they do occur will be more likely towards the east ne given where the PV wants to set up .

This new amplification has just shown up , it might be another false dawn but if we could squeeze a bit more out of that then it could turn colder for a time.

To be fair I'd take mild and not stormy if we can't get blue sky and frost

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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield

So the 12z gfs gives a block to the east altho not quite far enough north. +8 850s into Scandinavia, you couldn't write it

Edited by swfc
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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield

Also way in fi the biggest ridge in history. From the canaries threw Eastern Europe then towards the far east

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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)
16 minutes ago, Geordiesnow said:

I think excitement over a Pacific ridge into the Arctic is misguided, I have not seen a cold spell happening for us via a Pacific ridge as this just sends cold air through America and out into the Atlantic which means a powerful jet stream for us. We need too see WAA heading up to the pole via a high pressure cell before we can get excited about a cold spell. 

Anyways after a brief waveyness in the jet stream, for us it's looking like mild weather will quickly return. The next few days are going to be warm for some. A record breaking warm November is looking more and more likely. 

Anything that doesn't look like a bowling ball is a good thing/bonus and that Pacific ridge would perturb the trop pv,now if the forecast is right and we get a ridge too going up through the UK and up into Scandi/Urals,this would be classed as a wave 2,all part of the fun this model malarky and we may get lucky going into December.

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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)
6 minutes ago, swfc said:

Also way in fi the biggest ridge in history. From the canaries threw Eastern Europe then towards the far east

This looks a very dry run with plenty of fog and frost on the cards while the high migrates W/NW,lovely run.

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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20

Probably within the extreme of the envelope but the GEM is an amplified solution at days 5/6.  Let’s see what the ECM says - will it go with the flatter GFS/UKMO solutions or side with the GEM?

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

Anything that doesn't look like a bowling ball is a good thing/bonus and that Pacific ridge would perturb the trop pv,now if the forecast is right and we get a ridge too going up through the UK and up into Scandi/Urals,this would be classed as a wave 2,all part of the fun this model malarky and we may get lucky going into December.

Yeah PV looks shifted away from Canada at least in the depth of fi... 

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Posted
  • Location: South Oxfordshire
  • Location: South Oxfordshire
4 minutes ago, mulzy said:

Probably within the extreme of the envelope but the GEM is an amplified solution at days 5/6.  Let’s see what the ECM says - will it go with the flatter GFS/UKMO solutions or side with the GEM?

Gladly take the GEM, far more interesting 

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