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Model Output Discussion 29th December - Into mid-Winter.


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Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset
12 minutes ago, Seasonality said:

Because the UK has a mild maritime climate as the norm. Mild Atlantic weather is much more common than cold weather so of course it appears to "verify" more but really it is more like having a die marked with five ones and only one six and then marvelling how often one comes up when you throw it. *nb know your post is tongue in cheek but it is a sentiment I see expressed a lot here which should be addressed 

Bit simplistic mate, given we are affected by up to six different airmasses of which mild maritime is one.

I think most people's such comments are borne out of frustration that we have had all the right building blocks for something cold but somehow it has not transpired on a number of occasions. As a result, I don't think it's as simple as a plain return to zonal given such a weak Atlantic. Any return to zonal looks brief as the PV moves eastwards to the north of us.

Im still getting my head around this week, which at first glance looks fairly ordinary yet the N-W forecast gives me feel like temperatures of -10C at the end of the week.

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

Just looking at the UKMO and that brings an area of colder uppers north at T144hrs, there could be some precip associated with that but given my lack of confidence in the outputs whether its still there tonight is doubtful. You can see though that any breakdown maybe a bit messy as the models are still playing with taking some energy se'wards.

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

Some runs getting close to 15c later this month for ground temps in London the mean is lower at around 10c

t2mLondon.png

Pressure drops down to around 1000mb so a bit more unsettled to end the month

prmslLondon.png

 

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Posted
  • Location: Central Scotland
  • Weather Preferences: Polar lows are the dream
  • Location: Central Scotland

Large amounts of uncertainty clearly persisting into the medium range this morning, but the ECM gets to a place that I feel looks promising. If those height rises near Hudson Bay verify as per the 00Z run and we see the most potent segment of the polar vortex dropping in around Svalbard for a while then the dice could quickly start to roll in our favour. As energy then starts to head SE and potent cold builds up to the north it could be the perfect antidote to the mid-latitude blocking boredom we've had to endure for the winter so far.

Next few days will be interesting to see if this is an emerging trend and firms up or not, but I really hope it does as we still have a good few weeks of winter to play with...

 

Capture.PNG

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

gefsens850London0.png

A couple of things to note from the 00z ensemble - firstly the next week looks dry, after this we will see some rain. How much is open to debate. Secondly, there is still a great deal of scatter among the ensembles, and cold solutions aren't totally off the menu. There are also a number of incredibly mild members between 5-10c, and a couple that even exceed 10c!

Conclusion? We haven't got a clue! :D All possibilities still very much on the table.

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Posted
  • Location: North Wales 208m asl
  • Weather Preferences: crisp frosty days in Winter
  • Location: North Wales 208m asl
12 minutes ago, mcweather said:

Not really MP-R  Seasonality's description is a pretty good analogy of the U.K. Climate which is on the whole a mild maritime one with our weather coming at us on a west to east track off the Atlantic. Yes the text books may say we can be affected by six different airmass types but the reality is the ones from the west or southwest or south will always largely out weigh those from the north, east or southeast in any given year. Which of course is the reason that this place goes into meltdown when a sustained flow from  the north or east is shown.

Fergie often mentions in his posts about the longer range models returning to climatology and our climatology is without question a mild maritime one and that climatolgy means the dice are very much loaded against sustained cold and snow especially in lowland Britain. Which Is why despite being in my late fifties I can count the genuinely long cold and/or snowy periods in my life on the fingers of two hands.

Yes agree our climate is a mild maritime climate, I am in my early sixties and I agree there have not been that many notable cold periods over the years. My profile shows I have been a member since 2010 but I have been watching the fiorum for much longer than that. In fact I also remember the old BBC board with it's constant will it snow in my back yard type posts. Perhaps simpler times and less letdowns or is that rose tinted glassess? I do get the impression that the med term model output is messy and there is intermittant model agreement, but I will keep watching and hoping, perhaps dissapointment is easier to take as you get older.

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Posted
  • Location: Tonbridge, Kent
  • Location: Tonbridge, Kent

Can I just out that the 6z is very different (even in the short term within 168) to the 0z.

 

No Icelandic low, instead, lows passing directly over the country.

Edited by warrenb
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Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset
56 minutes ago, mcweather said:

Not really MP-R  Seasonality's description is a pretty good analogy of the U.K. Climate which is on the whole a mild maritime one with our weather coming at us on a west to east track off the Atlantic. Yes the text books may say we can be affected by six different airmass types but the reality is the ones from the west or southwest or south will always largely out weigh those from the north, east or southeast in any given year. Which of course is the reason that this place goes into meltdown when a sustained flow from  the north or east is shown.

Fergie often mentions in his posts about the longer range models returning to climatology and our climatology is without question a mild maritime one and that climatolgy means the dice are very much loaded against sustained cold and snow especially in lowland Britain. Which Is why despite being in my late fifties I can count the genuinely long cold and/or snowy periods in my life on the fingers of two hands.

Our climate is predominantly from the Atlantic which can be anything from SSW to N. Really only SSW to W is mild per se, so what you say is partly correct but also misses the bigger picture. Feel free to PM if you'd like to discuss further.

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Posted
  • Location: North East Cotswolds, 232m, 761feet ASL
  • Location: North East Cotswolds, 232m, 761feet ASL

After a bit of excitement last week hoping this week was going to be v cold with severe frosts, we are now looking at damp wet and pretty mild for the foreseeable - don't you just love UK weather as a coldie.  We do have a decent SSW forecast but this doesn't seem to be getting closer and sticks out beyond 300 hours on GFS, not sure why it isn't moving closer with each run though, but we need some luck from it I'd imagine.  Feb historically is the coldest and snowiest month so let's hope it lives up to that.

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire
6 minutes ago, Ali1977 said:

After a bit of excitement last week hoping this week was going to be v cold with severe frosts, we are now looking at damp wet and pretty mild for the foreseeable - don't you just love UK weather as a coldie.  We do have a decent SSW forecast but this doesn't seem to be getting closer and sticks out beyond 300 hours on GFS, not sure why it isn't moving closer with each run though, but we need some luck from it I'd imagine.  Feb historically is the coldest and snowiest month so let's hope it lives up to that.

Depends on location. For example the SE is going to see max temps around 4C this week. A slight warm up possibly on Thurs/Fri but the 06Z indicates only 2C for Saturday for most of the UK.

Rmgfs1324.gif

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Posted
  • Location: Warsaw, Poland. Formerly London.
  • Weather Preferences: Four true seasons. Hot summers and cold winters.
  • Location: Warsaw, Poland. Formerly London.
2 hours ago, MP-R said:

Bit simplistic mate, given we are affected by up to six different airmasses of which mild maritime is one.

I think most people's such comments are borne out of frustration that we have had all the right building blocks for something cold but somehow it has not transpired on a number of occasions. As a result, I don't think it's as simple as a plain return to zonal given such a weak Atlantic. Any return to zonal looks brief as the PV moves eastwards to the north of us.

Im still getting my head around this week, which at first glance looks fairly ordinary yet the N-W forecast gives me feel like temperatures of -10C at the end of the week.

No, you misunderstand me. I meant climate as in the Koppen climate classification Cfb, also known as oceanic, yes I'm aware the UK has different air masses influencing it, but there is no doubt what its climate classification is, it isn't even a borderline climate like some locations, that is a fact. So seeing as this tends to mildness for its latitude, and in the case of the UK just happens to have a lot of zonality, then any reversion to a climatological norm will be more likely to verify than solutions further from the climatological mean. Just trying to point out the logical fallacies a bit is all!

@nick sussex amongst others has pointed out an interesting disconnect between the models in the medium term, with UKMO and GFS against ECM. I'm fascinated because as nearby as Friday for Central Europe, and Warsaw in particular I'm looking at, the GFS is insistent on sub zero temperatures with -10/11 overnight but ECM considerably warmer. Pretty good ensemble support too and an interesting little model face off just four days away that I shall watch with interest. 

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

Very unsettled 6z run, by the end we return to square one - Vortex back at home, jet running right around the NH in its usual position. Not much more to add really!

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Whatever happened to NetWeather poster "Greenland 1080"?  Just for fun, here's a chart for him!

JMA 12z Jan 15th T+264:

J264-21.GIF?15-0

Highly unlikely to verify, at least to that extent as 1080 mb anywhere is exceptionally rare. Models do not always adjust the pressure on the high Greenland plateau to mean sea level values. I think that the world record high pressure is still 1085.7 mb recorded at Tosontsengel, Mongola (altitude over 750m) in December 2001 but this was also at high altitude. The highest adjusted record that I believe still stands was at Agata, Russia (altitude 261m) with 1083,8 in December 1968. The models have often shown 1060 or 1070 over Greenland which never materialised. More to the point, the JMA is trying hard to build HLB and ridging to HP in our vicinity -  at D11 and purely FI but several other model ens members do suggest this a just one of the cold options later in week 2. 

After my long serious post yesterday, I felt that was I due a more lighthearted break!

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Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL
16 minutes ago, mb018538 said:

Very unsettled 6z run, by the end we return to square one - Vortex back at home, jet running right around the NH in its usual position. Not much more to add really!

Perhaps one thing..

a very toasty PV at 10hpa. 

IMG_5478.PNG

it's at +384 I hear you say.. that May be the case, but it's being consistently modelled and that warming begins much earlier in the run.

192 and an already not to happy PV

IMG_5479.PNG

i think the big difference to last year is that the strat PV in particular was an almighty beast which wasn't going to be toppled easily, this year it's there for the taking. Only mid Jan, so still a lot of time. 

The 00z ensembles don't inspire much hope for cold in the medium term, but the low 2m temps peak (In terms of highest low) around the 27th/28th then start to drop off, I'll be keeping a keen eye on future updates.

IMG_5483.GIF

Edited by karlos1983
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Posted
  • Location: Leicestershire (hinckley)
  • Location: Leicestershire (hinckley)
2 minutes ago, karlos1983 said:

Perhaps one thing..

a very toasty PV at 10hpa. 

IMG_5478.PNG

it's at +384 I hear you say.. that May be the case, but it's being consistently modelled and that warming begins much earlier in the run.

192 and an already not to happy PV

IMG_5479.PNG

i think the big difference to last year is that the strat PV in particular was an almighty beast which wasn't going to be toppled easily, this year it's there for the taking. Only mid Jan, so still a lot of time. 

Charts at 192 and 384 rarely ever happen and the same is for these. Hear about an SSW that could save winter so often and yet they rarely materialise. I think the best we can hope for if a zonal setup returns will be the occasional colder blast for 1 day on the back edge of low pressure crossing from west to East.

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Posted
  • Location: Warsaw, Poland. Formerly London.
  • Weather Preferences: Four true seasons. Hot summers and cold winters.
  • Location: Warsaw, Poland. Formerly London.
1 minute ago, MKN said:

Charts at 192 and 384 rarely ever happen and the same is for these. Hear about an SSW that could save winter so often and yet they rarely materialise. I think the best we can hope for if a zonal setup returns will be the occasional colder blast for 1 day on the back edge of low pressure crossing from west to East.

You're right that charts at 192 and 384 rarely materialise exactly as modelled at a tropospheric level, but I believe stratospheric modelling has better verification (experts, please correct me if I'm wrong).

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Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL
6 minutes ago, MKN said:

Charts at 192 and 384 rarely ever happen and the same is for these. Hear about an SSW that could save winter so often and yet they rarely materialise. I think the best we can hope for if a zonal setup returns will be the occasional colder blast for 1 day on the back edge of low pressure crossing from west to East.

Actually I think this year most warming events have been modelled pretty accurately. I'm not saying it will definitely happen, that would be unwise, but let's be honest, your last sentence has not exactly been a true representation of this winter so far, so what makes you think that's what's going to happen going forward? 

The strat is a lot easier to predict than the trop at these timescales, as pointed out a few times on here.

Edited by karlos1983
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Posted
  • Location: Edinburgh
  • Location: Edinburgh
26 minutes ago, Bring Back1962-63 said:

Whatever happened to NetWeather poster "Greenland 1080"?  Just for fun, here's a chart for him!

JMA 12z Jan 15th T+264:

J264-21.GIF?15-0

Highly unlikely to verify, at least to that extent as 1080 mb anywhere is exceptionally rare. Models do not always adjust the pressure on the high Greenland plateau to mean sea level values. I think that the world record high pressure is still 1085.7 mb recorded at Tosontsengel, Mongola (altitude over 750m) in December 2001 but this was also at high altitude. The highest adjusted record that I believe still stands was at Agata, Russia (altitude 261m) with 1083,8 in December 1968. The models have often shown 1060 or 1070 over Greenland which never materialised. More to the point, the JMA is trying hard to build HLB and ridging to HP in our vicinity -  at D11 and purely FI but several other model ens members do suggest this a just one of the cold options later in week 2. 

After my long serious post yesterday, I felt that was I due a more lighthearted break!

JMA regularly over-cooks the highs over Grenland by 20-30mb...

 

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Posted
  • Location: iow england
  • Location: iow england
14 minutes ago, pdiddy said:

JMA regularly over-cooks the highs over Grenland by 20-30mb...

 

Not wishing to get to technical now, but didn't someone say that it isn't a real GH unless it has green and yellow colourings on the 500mb charts

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