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The hunt for cold - Model discussion (late November)

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)

Message added by Paul

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1 minute ago, Frosty. said:

Just some mild gunk to get through next week and then hopefully all roads lead to deep cold..potentially very exciting times to be a coldie and we have our own thread to enjoy it!:santa-emoji::drunk:❄️

Looking forward to the 12z Frosty 

Do you think this thread will get renamed in the near future 

To Hunt for Xmas cold.

Lots of difference between the 00z and chiefly the 06z 

And now winter Hazards in the Met forecast.

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jamstec performance since 2013-14 has been mixed based on 1st Nov winter seasonal forecasts:

2017/18: Partly Correcttemp2_glob.DJF2018.1nov2017.thumb.gif.45ec93726ec48f4902caa83c95d168f4.gif

temp2_glob.DJF2017.1nov2016.thumb.gif.64f7d7e11483db408eef483bf686edda.gif 2016/17: Correct

 

temp2_glob.DJF2016.1nov2015.thumb.gif.e7b776bd61c3d9c1b7cf5c87a39132e6.gif 2015/16: Wrong

 

temp2_glob.DJF2015.1nov2014.thumb.gif.d1e32e58cb474783f7e098354d0ca231.gif 2014/15 Partly correct

temp2_glob.DJF2014.1nov2013.thumb.gif.2cf099178d5d4416ee5400bdf6769258.gif 2013/14: Wrong

Edited by Froze were the Days

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image.png.952b291fbbd80d670221063b93b72022.png Just a little nod to the jamstec model. Think this sums it up nicely!!

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14 minutes ago, sorepaw1 said:

Looking forward to the 12z Frosty 

Do you think this thread will get renamed in the near future 

To Hunt for Xmas cold.

Lots of difference between the 00z and chiefly the 06z 

And now winter Hazards in the Met forecast.

Don't mean to pee on your bonfire but the Met 30 day outlooks haven't been hugely correct from late October onwards particularly for the period early November to early December when they forecast colder than normal temperatures and short lived milder spells...hopefully they'll be correct in their recent updates!

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7 minutes ago, Froze were the Days said:

Don't mean to pee on your bonfire but the Met 30 day outlooks haven't been hugely correct from late October onwards particularly for the period early November to early December when they forecast colder than normal temperatures and short lived milder spells...hopefully they'll be correct in their recent updates!

I'll take the risk 

My mother did.

I agree I'd like to see how accurate this potential cold spell is.

Edited by sorepaw1
Add

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22 minutes ago, Froze were the Days said:

Don't mean to pee on your bonfire but the Met 30 day outlooks haven't been hugely correct from late October onwards particularly for the period early November to early December when they forecast colder than normal temperatures and short lived milder spells...hopefully they'll be correct in their recent updates!

Yes, for all the Met Office upbeat forecasts for Nov/Dec these two months are currently both in the Top 5 milder than average CET's for 2018! For sure, at the moment, this will not be a front-loaded cold winter for the UK. 

Not that the experts on this forum were suggesting this but it does appear that at the moment the background signals are not supporting the longevity of cold spells, though the "potential" has at least been evident compared to other years. My own thoughts remain that an SSW is our best chance of sustainable cold in the New Year. 

As for the GFS 06z op, no real support, the mean T850s remains close or just above the seasonal mean pretty much through the whole of FI:

graphe9_1000_313_144___.thumb.gif.0faf868c94beda6c43ae4bff05bf0489.gif

The good thing this Winter is that the Op cannot be dismissed with alacrity as such an outcome remains viable, whereas in previous years such charts could be readily dismissed! So fingers and toes crossed...

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9 minutes ago, Mike Poole said:

Great spot, @Kirkcaldy Weather, this is absolutely what we want to see and what I have looked for at the end of the GFS and FV3 op runs for days now and failed to see.  This is the death of the vortex 💀.

P17 final chart as a 'still', nail this and we nail winter:

image.thumb.jpg.d54a5baf37a57537bc43cbbbf1e5f255.jpg

Thanks, hopefully this will be a growing trend in the next few runs 👍 🔥  and the PV will be at the 🔚 of its life 💀

and a growing signal for a couple of warming attempts 

NH_TMP_10mb_240.thumb.gif.d5d4bdbc420370b0b243395e85a51952.gifNH_TMP_10mb_384.thumb.gif.a0f60fa88de9043a8704b0a83eb6e2ee.gifgfs_t30_nh_f240.thumb.png.44efcc11780ce112efad6dc12c6d7137.pnggfs_t10_nh_f240.thumb.png.63d863f4fae45da7d289c570857ca538.png 

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26 minutes ago, Catacol said:

A split at that angle, should it descend similarly to lower levels, would lead to a properly cold January. To be honest couldnt really ask for a better location and angle of the split especially given timing. I hope everyone has taken the time to service their boiler. If not - get it done........

However usual caveat....one run....one perturbation....more water to flow under the bridge yet....

I think we were expecting the initial 'technical' SSW will be a displacement. The expectation is now that a split will follow but we were reliant on analogues (2013) as to what that split would look like.  It seems more real to me now having finally seen a split on one of the models, and as you say if that is how the split would happen, it would send the UK into the freezer in January.  Interesting times just got more interesting. 

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9 minutes ago, Catacol said:

Output is beginning to recognise the significance of the timing of +MT, MJO progression, background Nino and impact of heat transfer onto the vortex. Height rises out west to drive the trough further south, followed by invigoration of that trough via falling momentum phase - and meanwhile Greeny and Scandy height rises begin to link up. It's a near perfect sequence - and once again for all those moaning last night about how we cant predict anything and its all random blah blah - nonsense. There are spanners that regularly get thrown into the works and mess things up...but broadscale prediction is getting ever more possible with better and better tools. And this is one instance where we havent had a sudden uptick in solar activity, or a tropic storm in the wrong place....and the cold pattern will be completed on schedule. You have done well Lord Teleconnect....and now I sense that you wish to continue the search for the split vortex....

Hehe. Such fun. But to anchor my mid afternoon drivel into something with a graphical solidity about it - how about a GFS ensemble image. Usually EPS gets the bigger coverage, but I think GFS has been handling the extended picture rather better in recent days. By the end of next week we have a very good signal for a cold trough with signs of continental cold being able to back west

gfs_z500a_nhem_29.thumb.png.75a85a428435d0b90b5d6989ff8f679f.png

....and then within a few more days the heights back further west to Greenland and begin to pull in an ever more frigid flow from the E/NE

gfs_z500a_nhem_37.thumb.png.69dc4feffafbfb38f105a46a4800dab9.png

Being brutally honest cold rain for many will have to be endured as we progress through this phase - but the end result looks like an increasingly cold and wintry one. 

Patience my friend. In time the Beast will seek you out, and when he does, you must bring him to me. He has grown strong. Only together with the additional benefit of a downwelling split vortex can we turn him to the Dark Side of The Force.......

Isn't that the gfs 06z op anomaly? Not the ensemble mean anomaly.

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18 minutes ago, blizzard81 said:

Isn't that the gfs 06z op anomaly? Not the ensemble mean anomaly.

Quite right - adjusted.

Edited by Catacol

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Just thought I’d say I’ve got a yellow warning out for my area tomorrow now ( north Hertfordshire) . Maybe a few surprises tomorrow. 

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Cmon GFS keep the faith!!

UKMO also getting into range for crimbo now hope it doesnt follow EC!!

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UKMO T144:

image.thumb.jpg.ab32fe417213d59668ce558833a784f6.jpg

I speculate that this may lead to a similar weak build of heights to the NW later, as per the ICON, so I think this holds more potential than the morning run.

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1 minute ago, Mike Poole said:

Let us not have our eyes on the longer range models, that we lose sight of tomorrow.  Here's the HIRLAM 12z cumulative snow fall chart to T32:

image.thumb.jpg.88103e98cc7e39c6005612c8d3e7c2d7.jpg

Of course, even if that happens it won't all settle, but it is still an impressive chart.

Does that include freezing rain aswell?

 

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22 minutes ago, Had Worse said:

Does that include freezing rain aswell?

 

No HIRLAM doesn't distinguish freezing rain. Understand there might be an issue with this in some parts of the UK though. So here's GFS 12z T27, freezing rain purple, it's a really coarse model so very poor at resolving this.

image.thumb.jpg.e7f032c1800826cae1be7c3f63d9f8a6.jpg

More local model the NMM an hour earlier, but from the 6z. might put some detail on that:

image.thumb.jpg.8ad71fc73baf35289e3073bef4723435.jpg

The purple hatched area ties in well with the Met Office warning, but note the time 2pm - might catch people unawares this one.

Edited by Mike Poole

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10 minutes ago, Mike Poole said:

Let us not have our eyes on the longer range models, that we lose sight of tomorrow.  Here's the HIRLAM 12z cumulative snow fall chart to T32:

image.thumb.jpg.88103e98cc7e39c6005612c8d3e7c2d7.jpg

Of course, even if that happens it won't all settle, but it is still an impressive chart.

I thought the MO were going for snow in Scotland mainly 

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