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Hunt For Cold: Model Discussion - Heading Into Christmas


Paul
Message added by Paul

If you're hunting for cold potential in the model output, this thread is for you. But if you'd like to look more widely at the models, please head over to the general model discussion thread.

This is a model related thread, so a general, frequent theme of the model output is a given, but it will not be strictly enforced:

  • Some topic drift, humorous responses etc are fine
  • Posts likely to lead the thread off on an entirely off topic tangent are not ok. For example (but not solely limited to): Posts entirely or mainly about Met Office, BBC or media forecasts with little or no model context, and posts solely asking for a weather forecast in a specific location.
  • Posts which start with something like 'I know this is off topic but ...' are not ok.
  • Posts which break the forum guidelines are not ok (eg trolling, troll-hunting, weather guilt tripping, overly defensive/aggressive, abusive, disrespectful to others)

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Posted
  • Location: Nr Chelmsford, Essex
  • Weather Preferences: Hurricanes, Thunderstorms and blizzards please!
  • Location: Nr Chelmsford, Essex

Well there you have it.  If any more evidence needed to be seen to how the GFS is struggling, here's the 6z at 144 vs the 0z.

image.thumb.png.0ff200c20a4e8a1ec414f07fca421990.png  image.thumb.png.92a49e11b441edb6efad81761c603e83.png

That's quite some difference only 6 days out..... something's definitely brewing!!

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Posted
  • Location: Poole, BH14
  • Location: Poole, BH14

The temperature at 10hPa over the North pole seems a bit higher than expected, closing in to -10C whereas models only expected the peak temps in the North Pole to be around -20C. Also posted this in the strat thread but may get seen more here. Surely this is a good thing?

FB_IMG_1546164403030.jpg

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Posted
  • Location: Neath Valleys, South Wales 109m asl
  • Location: Neath Valleys, South Wales 109m asl

Given the 6z has now jumped ship of its Atlantic dominated dross I would be surprised not to see Exeter drop their mobile spell.

image_png_46ecc1080e6c63a3d2c79f020310be7f.thumb.png.45479fadd8d1c46a38cc4a9ddd71b44e.png

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
1 minute ago, ALL ABOARD said:

Given the 6z has now jumped ship of its Atlantic dominated dross I would be surprised not to see Exeter drop their mobile spell.

image_png_46ecc1080e6c63a3d2c79f020310be7f.thumb.png.45479fadd8d1c46a38cc4a9ddd71b44e.png

Yup, GFS caves in to Euro..

What a suprise.. not.

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

Just a slight difference from 00z to 06z

8D019EA0-3B88-4D6C-9C01-5C9B349AEE40.thumb.png.2975e7e06185264cf143165a51d1b7a0.png5D8FDE55-FB3C-4291-8238-14A7A068C2F7.thumb.png.5ede92d3d1d80fa26de85d80b5b45b11.png

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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill
2 minutes ago, ALL ABOARD said:

Given the 6z has now jumped ship of its Atlantic dominated dross I would be surprised not to see Exeter drop their mobile spell.

image_png_46ecc1080e6c63a3d2c79f020310be7f.thumb.png.45479fadd8d1c46a38cc4a9ddd71b44e.png

The op is just switching between clusters, it may flip again on the 12z, or maybe the GEFS will suggest a Eureka moment and the ECM outlook will be backed up? Certainly, the 06z follows the ECM, with the Atlantic wave cutting through the western Atlantic trough, and that is what we hoped.

Not that this will bring cold and snow in the medium term, but an HP holding pattern IMO is preferable to a zonal flush! Possibly further waves from the Atlantic may push further WAA to the north which in the long term can only be beneficial. My interest is more in FI to see if there are any trends to how the inevitable mid-latitude cold influences the UK.

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

Hints of cross-polar ridging? As any attack from the North is likely to be preceded by westerlies, nowt much to worry about IMO:

image.thumb.png.9992be48ad4c9a49d5fdf1949ba336b6.png

edit: Mike beat me to it!

image.thumb.png.4374c8de188f2f673ab875dcaa0ce9e3.png

Edited by Ed Stone
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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

GFS 6z going full on for the northerly in FI

image.thumb.jpg.d2bb530b6b70ed83ad6f4759ae41c14e.jpg

Not saying this will necessarily be followed up by the 12z, but good to see a GFS run like this, and hope there are more on the next few runs.

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Posted
  • Location: Essex Riviera aka Burnham
  • Weather Preferences: 30 Degrees of pure British Celsius
  • Location: Essex Riviera aka Burnham

Followed by a toppler...no doubt and into default mode.

Edited by Froze were the Days
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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill
2 minutes ago, Mike Poole said:

GFS 6z going full on for the northerly in FI

image.thumb.jpg.d2bb530b6b70ed83ad6f4759ae41c14e.jpg

Not saying this will necessarily be followed up by the 12z, but good to see a GFS run like this, and hope there are more on the next few runs.

Just the pattern repeating, oscillating HP fed by another wave. Though with the heights better placed on this run, the UK gets the topple as a direct hit for transient cold and snow.

However with the PV as below...

gfsnh-0-336_rdg9.png

...it seems unlikely that we can get HLB'ing to sustain at this point in time.

Just another run and I suspect the D10 chart from GFS will have a very low verification score, so more about trends and potential than specifics!

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Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

Interesting too see if it'll flip back again on the next run. If it doesn't the ecm will now probably flip due to boredom of showing the almost the same set of charts for days.

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Posted
  • Location: Poole, BH14
  • Location: Poole, BH14

This according to weather trending. The medium-range models may not be 'seeing' the SSW yet. It can take up to a couple of weeks for a stratospheric reversal to work its way down to Earth (if indeed it does). There's a blocking trend in models compared with a few days ago but possibly not SSW-related.

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Posted
  • Location: Near King's Lynn 13.68m ASL
  • Weather Preferences: Hoar Frost, Snow, Misty Autumn mornings
  • Location: Near King's Lynn 13.68m ASL
57 minutes ago, Mike Poole said:

Fascinating output at the moment, I'm minded of the period watching the modelling around the time of the last SSW in February.  There was much angst until the event had actually happened and the real signal gradually became clearer.  I expect much the same this time, we're not guaranteed the cold solution again, these events are all different, just pointing out the uncertainty has still to be resolved.  

One thing that is possibly worth noting that it does look now like a prolonged wind reversal in the strat i.e. this isn't going to be one of those technical reversal - just -occasions, which surely must account for some of the times an SSW doesn't lead to cold for the UK. 

The GEFS zonal wind chart shows the reversal on Jan 1, and all but 1 member still reversed at the end of the run some 2 weeks later,  with the mean about -10m/s throughout:

image.thumb.jpg.3fc81dd59f458c0132c4368fa09413ec.jpg

As this is the 0z suite, as others have posted there were some good members for trop evolution in that suite - all looking very promising.

 

Just a small pedantic note, but the zonal plots run once a day at midnight on Hannah Attard’s site, so the above plot will be based on yesterday’s run: presumably the 12z. 

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
11 minutes ago, bluearmy said:

Be interesting to see this op run on the ‘weather is cool’ strat site re downwelling ............

It maintains the split for the whole run at 10mb although the canadian segment moves closer to us at the end of the run

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

Another capitulation by the GFS towards the ECM upstream by day 6.

Its still a bit quicker than the latter with phasing and the speed of the low out of the ne USA but it’s getting there .

NCEP have little confidence in  their own model with northern and southern jet phasing and you can see why .

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
8 minutes ago, northwestsnow said:

Blimey.. it was woefully wrong at day5...i think its a big leap of faith to expect it to right at day 10/11..

Sorry that I can't confirm that, NWS, but my TARDIS is having its MOT today!

But, anywho, the 06Z is still broadly in line with the MetO 16-30-day updates, so writing the model's entire evolution off (at this early stage) seems as perilous as taking its output as gospel...?

image.thumb.png.2f22375209d5c56d57d8968baba5f95a.png

 

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
9 minutes ago, Yarmy said:

Just a small pedantic note, but the zonal plots run once a day at midnight on Hannah Attard’s site, so the above plot will be based on yesterday’s run: presumably the 12z. 

It's ambiguous, actually, so I see why you say this - whether it's the time of the model run, or when the plots are done.  However, a while back someone posted the identical plot from a different website that specifically said the 0z, and I checked them and they were identical, so I believe they are in fact the 0z.

Edited by Mike Poole
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Posted
  • Location: Near King's Lynn 13.68m ASL
  • Weather Preferences: Hoar Frost, Snow, Misty Autumn mornings
  • Location: Near King's Lynn 13.68m ASL
14 minutes ago, Mike Poole said:

It's ambiguous, actually, so I see why you say this - whether it's the time of the model run, or when the plots are done.  However, a while back someone posted the identical plot from a different website that specifically said the 0z, and I checked them and they were identical, so I believe they are in fact the 0z.

If you look at the plot though, the black line (the analysis) ends at 12z on the 29th, and the red lines (the forecasts) begin then. If it were from this morning’s 0z, the red lines would start at 0z on the 30th. 

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
6 minutes ago, Yarmy said:

If you look at the plot though, the black line (the analysis) ends at 12z on the 29th, and the red lines (the forecasts) begin then. If it were from this morning’s 0z, the red lines would start at 0z on the 30th. 

You could be right then, but I can also recall an instance a while back of someone chasing down an ensemble member that went really really negative and it turned out to be a 0z member. If anyone knows for certain which suite is used, please could you clarify?  Thanks in advance.

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Posted
  • Location: Near King's Lynn 13.68m ASL
  • Weather Preferences: Hoar Frost, Snow, Misty Autumn mornings
  • Location: Near King's Lynn 13.68m ASL
5 minutes ago, Mike Poole said:

You could be right then, but I can also recall an instance a while back of someone chasing down an ensemble member that went really really negative and it turned out to be a 0z member. If anyone knows for certain which suite is used, please could you clarify?  Thanks in advance.

I’ve never been able to find archived GEFS online, but @Interitus posted an individual member I requested a little while back.

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