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The hunt for cold - Model discussion (late November)


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: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK
17 minutes ago, Tim Bland said:

Pray the GFS(p) drops this pattern in FI shortly 

 

8BFBDC30-D188-4BBC-97AB-4498FC725C93.png

That looks dreadful....completely at odds with all other output and guidance at the moment though, so no worries yet!

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

Signs that the middle of next week may be shifting towards a colder outlook judging by the GFS ens. The high to the NNW asserting itself and building cold to our north.

Will update the swingometers after I have had my dinner

So a bit of a boring weekend probably weatherwise but after that it may be more interesting.

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

Phew feel model fatigue kicking in and it's only November early rutting season also!!, anyway the gFS 12z does take the well documented low further south which does bring the colder 850s that bit further south before things blow up in fi.Thing to watch imo is a rise in pressure towards Scandinavia if we are to get a sustained push of cold going forward.i don't think the heights towards Greenland "kind of West based "will stop the trail of lows crossing the UK on a more northerly track.

Edited by swfc
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Posted
  • Location: st albans
  • Location: st albans
5 minutes ago, booferking said:

NAVGEM agrees with UKMO pedal to the metal.

 

Chart of the day for me at 144hr

navgemnh-0-144.png

whilst NAVGEM isn't usually the model of choice, it does show what can happen if the trough to our west disrupts favourably …..

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

^^ Its going to happen 100%-

If you were to draw a cone like NOAA scotland would be in the 10% zone, Midlands 30% , Southern eng down to Northern 60%...

What’s going to happen Steve  ? Do you mean snow along the cold mild boundary ? Sorry just logged on .

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

The fog is slowly lifting

I think we have a reasonable idea of where we will be 7 days+ though we can't know the detail and GFS 12z should be fairly representative of the mean charts

gfsnh-0-156.png?12

Atlantic tlow disrupting SE

Weakish high pressure to NW

Arctic/Scandi trough pushing S/SE to our N/NE

The detail will depend on timing and sharpness of the Arctic trough and how much the Atlantic low disrupts.

Best case scenario is P1 whereby the Arctic trough brings in cold Arctic air across the UK before the trough disrupts nicely SE into the continent bringing the chance of a snow event and keeping us in the cold air.

gensnh-1-1-228.pnggensnh-1-0-192.pnggensnh-1-0-240.png

We will need to lucky for that to come off though.

More likely we get some middle ground and rain rather than snow.

Other ways of chasing winter wonderland are a weak signal in deep FI for heights to build to our NE with possible Scandi high and/or Atlantic ridge to form but all rather vague at the moment.

@bluearmy talked of a depressing signal in the European ensembles for heights to build to our SE yesterday. I believe this was a consequence of those ensembles having the same lack of resolution as GFS to resolve the complex distribution of energy through the mid term. If so then this signal should weaken and be replaced by positive height anomalies further N into Scandi a little later and if anything negative height anomalies to our SE from roughly day 7 through 10. That would be good news.

Edited by Mucka
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

I think the issue at the moment is where the main blocking will end up. We really want the high to the north blocked off and not allowed to seep heights westwards towards Canada .

In these set ups the Atlantic will attack the weak point which is over the UK . The right balance keeps the block just far enough east with shallow features moving east and delivering you know what to favoured areas.

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Posted
  • Location: st albans
  • Location: st albans
6 minutes ago, Mucka said:

 

@bluearmy talked of a depressing signal in the European ensembles for heights to build to our SE yesterday. I believe this was a consequence of those ensembles having the same lack of resolution as GFS to resolve the complex distribution of energy through the mid term. If so then this signal should weaken and be replaced by positive height anomalies further N into Scandi a little later and if anything negative height anomalies to our SE from roughly day 7 through 10. That would be good news.

the charts haven't looked very convincing for a good few days ………….. whilst the eps mean has high euro height anoms, they aren't significant and the slp mean has low anomolys across much of western Europe so i doubt the mean charts are particularly helpful.  the gefs has a cluster of sliders in its higher res offering pre day 8. split flows post day 8 will not be best shown on the gefs ……..

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .
6 minutes ago, Steve Murr said:

Low sliding ESE --- with the cone highlighted above !

Thanks Steve , I still can’t find the cone but get your drift ! 

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Posted
  • Location: North East Cotswolds, 232m, 761feet ASL
  • Location: North East Cotswolds, 232m, 761feet ASL
4 minutes ago, mulzy said:

Just for fun - the GFS Control run is what I would call interesting.

GFSC00EU12_360_1.png

Clear outlier (for now!)

 

What a fantastic chart, if only. Looking at the ENS chart SS just posted you can clearly see it as an outlier, -13c uppers early Dec though - impressive. 

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester
1 minute ago, bluearmy said:

the charts haven't looked very convincing for a good few days ………….. whilst the eps mean has high euro height anoms, they aren't significant and the slp mean has low anomolys across much of western Europe so i doubt the mean charts are particularly helpful.  the gefs has a cluster of sliders in its higher res offering pre day 8. split flows post day 8 will not be best shown on the gefs ……..

Thanks.

We are not looking to nail the shortwave pattern for FI though just looking for trends.

I like to look through the individual ensemble members and their evolution and build a mean in my head as I find this more helpful for spotting potential trends than a mean snapshot.

I'm hoping though that we see (you report) any positive mean heights to our S slowly move W through the mid term with a signal for weak negative anomaly to the SE in the 7 to 10 day range.

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

image.thumb.png.aada9a4d9463bd7287a7c22c71cf5bd6.png

So the 12z swingometers. November 25th is definitely reaching a consensus of temperatures being close to average or a little below. The changes are occuring in the medium to longer range output.

image.thumb.png.e94eb6b1e8c198508120ecd59183a6d6.png

The 12z's are showing a move away from mild conditions prevailing at the start of December and it looks as though things could fall anyway. The optimistic side to me is hoping for something like P13.

GFSP13EU12_270_1.png

 

* before the low blasts the cold away. Fair chance something like this could happen or we get the dreaded west based NAO. I'm sitting on the fence today.

 

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL

Battle royal between heights trying to scupper a southerly tracking jet and the high to our north west.Im a bit reminded of late Dec 1978 with the current charts..

NOAA_1_1978123000_1.png

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

Battle royal between heights trying to scupper a southerly tracking jet and the high to our north west.Im a bit reminded of late Dec 1978 with the current charts..

NOAA_1_1978123000_1.png

Was thinking the very same thing myself, NWS...so I'll keep an open mind. I would do the same thing in response to sightings of piranha in the Thames...Honest!:santa-emoji:

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