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Model output discussion - Winter has arrived and the hunt for cold is on


Paul

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Posted
  • Location: Wyke regis overlooking Chesil beach.
  • Weather Preferences: Snowfall
  • Location: Wyke regis overlooking Chesil beach.
37 minutes ago, Catacol said:

Blimey - you got a webcam in my sitting room?! Hehe - I was just toying with taking up Mr Frosts promise of him eating a sledge if all of us don’t see a snowflake this year. Some in this forum have no idea how lucky they are not to live in Somerset......

Next week will certainly be interesting, just to see the impacts of the Pacific jet extension on the back of +EAMT and witness its ability to spike the pattern around the hemisphere. The truth of the end of next week is too far off to bin entirely as a cold snap because the magnitude of the wave breaking that will accompany the jet surge is open to interpretation and I would imagine the models will struggle to get a precise handle on how that surge will pan out. Bear in mind it hasn’t even reached the west coast of the US yet.

The bigger question really is what happens when that surge passes. I posted optimistically that a block might form with sufficient longevity to carry through to later in December. But I don’t think in truth this is the most likely outcome. The MJO is not positioned favourably yet, and from pirated tweets I’ve seen today it would appear any rise in GLAAM has slowed to a neutral crawl. In blunt terms this means that support for sub tropical high pressure will increase, and in turn that means less support for a -NAO pattern. This was my gut feeling going into December - the spike in torque adds some spice to the short term, but it doesn’t change the overall direction in the first half to two thirds of the month.

Much still hangs on the extent to which tropical convection can emerge from phase 6 and get to the maritimes, the strength of that convection and the condition of the vortex in the context of QBO progression. I am an avid reader - comes with my profession - and I can tell you that opinions on this are divided across the net. I painted two distinct pathways for winter in my forecast because the junction represented by the potential pathways at the end of December was pretty clear, but genuinely I think the direction of travel at that point hangs in the balance. The snowper in me wants the amplified, Nino attractor pathway smoothed by a transition to an eQBO and a vortex in collapse; the realist in me also sees the distinct possibility of vortex recovery, delayed QBO transition and an MJO struggling for effect in the context of a standing wave in MJO phase 2 that helps prevent helpful impacts in the extra tropics - helpful if you want cold that is. A kind of half way house blend is obviously a compromise solution.

Don’t need charts tonight. For now enjoy a rollercoaster ride into next week and NWP output that I suspect will catch the eye again before the impacts of jet resurgence fades, and in the meantime perhaps we can get some evidence emerge as to how the run in to Xmas may develop vv the tropical signal and vortex as drivers. It’s only Dec 4. Plenty of time for multiple rollercoaster rides....

A superb post from Catacol giving the bigger picture and honest assessment of the point at which things might or might not go in our favour winterwise. 

Certainly much more interesting than all the I told you so posts about a cold snap that hasn't even happened yet and could still possibly upgrade given the current model volatility.

Winter weather watching has always been a game to test the patience of a saint in lowland areas of the UK that's why we like to let ourselves get just a little bit carried away when like yesterday a model shows my locale in line for a foot of snow. Yes I knew it was very unlikely but just to be able have some albeit faint hope that it might come to fruition is somewhere I would far rather inhabit than the sniffy Environs of I told you so ville.

Edited by Broadmayne blizzard
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Posted
  • Location: HANDSWORTH BIRMINGHAM B21. 130MASL. 427FT.
  • Weather Preferences: WINTERS WITH HEAVY DISRUPTIVE SNOWFALL AVRAGE SPRING HOT SUMMERS.
  • Location: HANDSWORTH BIRMINGHAM B21. 130MASL. 427FT.
33 minutes ago, Allseasons-si said:

The UKMO is not in range of the cold synoptic and besides,it's not happened yet.

 through a fair point how ever when all three model singing from the same hymn sheet then most of the time it’s only going one way

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.

Well that is very interesting - the ECM mean or best data has max temps for my area not getting above 4c from next Thursday until after next weekend.

Edited by feb1991blizzard
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Posted
  • Location: St Austell,Cornwall
  • Location: St Austell,Cornwall
28 minutes ago, Allseasons-si said:

Icon 120 sure doesn't blow up that low in the Atlantic,what ramifications would this have later on?

iconnh-0-120.thumb.png.33dc6d73a8158a155d49989f3a72e019.png

 

The PV also looks further into Russia/Scandinavia?

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Posted
  • Location: Tyrone
  • Location: Tyrone
3 minutes ago, feb1991blizzard said:

Well that is very interesting - the ECM mean or best data has max temps for my area not getting above 4c from next Thursday until after next weekend.

What you make of ICON that low a lot further south looks like it won't blow up as much.

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
1 minute ago, booferking said:

What you make of ICON that low a lot further south looks like it won't blow up as much.

Although the initial plunge of cold doesn't get as far south than the 12z, it could be a better run further out than its 12z as that ended disastrously, so an upgrade but coming off a very low base to be frank.

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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)
9 minutes ago, syed2878 said:

 through a fair point how ever when all three model singing from the same hymn sheet then most of the time it’s only going one way

This wasn't the point that i was trying to get to you,yes all three:-UKMO,gfs and ecm all look broadly similar at 144,it's after this time frame that the models are showing the cold spell

but i also pointed out in my previous post that this is still several days away and will not be nailed on yet.

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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)
1 minute ago, booferking said:

Slight upgrade with jet on this run gfs could this set a new trend. Straw clutching i know

One thing of note is the mild-er 850's get squeezed out further south

18z at 144 v 12z 150

gfs-1-144.thumb.png.c7492e9b26799927d5744162eced41f6.pnggfs-1-150.thumb.png.48c170627a0c854a3cae9658bfeabad6.png

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

As I stated last night, I felt the 12z GFS would be the 'high water mark' for the cold spell that may or may not occur next week, but I also feel that the models have probably over-corrected today.  I maybe wrong, but let's see how tomorrow unfolds.  

Onto the 18z, out to 174 and the low north of the UK is not as intense at the 12z so is allowing the pattern to dig further south.  Maybe the start of the rebound?  18z first.

image.thumb.png.5712054fa378779514eba11f802ce618.pngimage.thumb.png.863ceedadd4948286e253b705c822f22.png  

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

Mr PV goes on holiday to the eastern seaboard this evening!!! Epic PV and where did Greenland go ???

Edited by swfc
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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 gfs 18z has two northerly shots from 192>300,i am quiet happy with that,i would bite someones arm off for this synoptic than waiting for Feb/March for a cold snap/spell of recent winters

it would have to come off of course 

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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield
26 minutes ago, Mike Poole said:

Been busy today, caught up, and then pub run T240:

image.thumb.jpg.01c2e61461e4984fd4946d43c4f05382.jpg

If it was my pub GFS would be barred!  

Tempted to give up this hobby, not because of the weather, not even because of the models, but because of the pessimism...I cannot see the point of it.  We won't see...

Sometimes it's realism,sometimes a wind up but Mike it's only weather! Worse things in life going on.btw have you got the snow charts for GFS 18z at 300hrs

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
1 minute ago, swfc said:

Sometimes it's realism,sometimes a wind up but Mike it's only weather! Worse things in life going on.btw have you got the snow charts for GFS 18z at 300hrs

image.thumb.png.8af1595a6b20428ab7ab164d101aeb11.pngimage.thumb.png.e16ae1d235ab3fbe53dffd2301633427.png

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Posted
  • Location: Solihull, Midlands. (Formerly DRL)
  • Weather Preferences: Sunshine, thunder, hail & heavy snow
  • Location: Solihull, Midlands. (Formerly DRL)

Regarding that Low Pressure in the Atlantic for early next week, both the ICON and GFS 18Z show how there is likely to be some further changes to the modelling and behaviour of the Low:

GFS 18Z at 120 hours

B879EFAB-F96C-4607-804A-99B8DECBB3DD.thumb.jpeg.a605bc315e0863c855b4f5362cda5cd6.jpeg 
 

ICON 18Z at 120 hours

360C983E-9742-4F17-A134-EF807E0FEE49.thumb.jpeg.3b7122b098bd9b50cdf259ec22deaf5f.jpeg

The general overall pattern may be quite similar. But both these 2 models showing differences to the development of that Low. The ICON having a less aggressive more Southerly placed Low in the Atlantic, where as the GFS has the main area of the Low further North in the Atlantic accompanied by lower, upper, heights. The ICON 18Z may have had too many wines from the model night club, since most other models generally model that Atlantic Low fairly closely to how the GFS has it. And maybe if it went out further, the ICON would follow a similar route to the likes of the GFS

I think, though, it can go to show that even within 120 hours the charts aren’t always certain of things. Even if it might be mostly the smaller details and surface features around that time-frame. Some big differences at 5 days out isn’t totally unfeasible, mind.

I feel like at the moment, a number of the models may be over doing the strength of that Atlantic Low next week. May just find more of a shallower feature occurring, which could lead to more of a wintrier, chillier, evolution for the UK. A deep(ish) Low, though, would probably appear to be the most popular scenario at the moment and it’s probably more likely than not that the Low will end up going to the North of the UK rather than to the South. But again, with the differences both the ICON and GFS 18Z show above (despite the fact there could be an overall theme emerging next week), then I feel it’s not all sorted yet.

In case it does become tempting, it might be best to padlock the prams for now, so no teddies or missiles get flung out. Trust me, it was difficult for me to lock up my little pink pram, but in the end it was worth it. 

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Posted
  • Location: NR Worthing SE Coast
  • Location: NR Worthing SE Coast

Anyone else think the next set of operationals will be an upgrade,lots of cold runs in the ensembles,and nothing of this cold spell is in the more reliable time frame yet.

Lots of more fun on the rollercoaster yet,folks!

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Posted
  • Location: Bethnal Green
  • Weather Preferences: Snow and Cold
  • Location: Bethnal Green
22 minutes ago, SLEETY said:

Anyone else think the next set of operationals will be an upgrade,lots of cold runs in the ensembles,and nothing of this cold spell is in the more reliable time frame yet.

Lots of more fun on the rollercoaster yet,folks!

Yes to this.

I have followed this forum since before 2005 (can't remember exactly when).

The run up to big events is often forecast and there is a propensity for blocking and it's a question of how cold it will be.  This time it's going to be a rollercoaster in so far as it's a question of will there be cold in the right places.  BUT... there is a chance, and while that chace remains the chase is on...  And that is why I follow this thread.

For any younger members, when I lived in County Durham, in the run up to December 2010, and the lampost watching, and then the 1ft+ snow that occurred widely... it'll happen again and it's worth the chase.

Edited by Jonathan F.
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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
20 minutes ago, Jonathan F. said:

Yes to this.

I have followed this forum since before 2005 (can't remember exactly when).

The run up to big events is often forecast and there is a propensity for blocking and it's a question of how cold it will be.  This time it's going to be a rollercoaster in so far as it's a question of will there be cold in the right places.  BUT... there is a chance, and while that chace remains the chase is on...  And that is why I follow this thread.

For any younger members, when I lived in County Durham, in the run up to December 2010, and the lampost watching, and then the 1ft+ snow that occurred widely... it'll happen again and it's worth the chase.

Significant cold spells are relatively easy to forecast in advance...think 2010, Jan 2013, March 2013, end of Feb 2018. I can hardly recall any significant cold spell in recent times that have come out of thin air at a very short lead time. 

With this in mind, I don't see anything within the next 4 weeks at least that could be classed as significant in terms of cold. 

The thing is, the odds are doubly stacked against us because even if we were looking at a protracted cold spell, it could all go wrong (think last winter). Amateurs and professionals alike were convinced we'd see some bitter cold.

I'll just add that what I'm saying doesn't preclude cold 'snaps' with a short window for snowfall, but anything more than that this side of new year, forget it.

Edited by CreweCold
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Posted
  • Location: frome somerset 105m ABSL,
  • Weather Preferences: cold snow, thunderstorms
  • Location: frome somerset 105m ABSL,

This doesn’t bode well!! 
 

EC0E853F-41EB-49A1-8A69-29B670DB682C.jpeg

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Posted
  • Location: Kendray,Barnsley,God's county.
  • Weather Preferences: Snow freezing fog heatwave thunderstorm
  • Location: Kendray,Barnsley,God's county.

Great forum and info as always keeps it up thanks. I for one haven't yet given the cold hunt for next week. Roll on the 00z lol

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