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Paul

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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9 minutes ago, northwestsnow said:

Well its that time of year when iactually don't mind the 12 hour night shift- gulp!

I get to sneek out and watch the 00z runs before everyone else 😄

Big EC coming up!!

It’s that time of year where the 4.30am alarm absolutely sucks because it means I have to miss the 18z! We’re an odd bunch aren’t we 😂

Would be nice to see the ECM upgrade this morning too so we get a full house!

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T168 on parallel, compared with the 12z from the past two days. Acceptably consistent considering it's D7/D8/D9, but that deeper "cut" from the NE has been phased out today, and the Atlantic low is looking more like the ECM mean

gfs-0-168.png?12  gfs-0-192.png?12  gfs-0-216.png?12

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That low to the west of Ireland is much deeper and closer on tonights GFS P compared to the 06z

12z

gfs-0-228.thumb.png.de9013996e4acc322ff5954240013adb.png

06z

gfs-0-234.png

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3 minutes ago, Steve Thexton said:

FV3?? guys for us mere mortals 😕

 

Look at all that lovely cold air just to our east on the RV3, won't take much for that to edge westwards surely.🤔

gfs-0-300.png

gfs-1-300.png

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Yes, i was just thinking the FV3 in deep FI was looking a bit Jan 1987ish  -  only a teeny weeny bit though.

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6 minutes ago, Steve Thexton said:

FV3?? guys for us mere mortals 😕

 

It is the soon to be GFS. Currently called the GFS parallel or GFS(p) if trials go well it will replace GFS in Feb or March. So far it’s outperforming the current GFS so very likely that it will.

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Think that any cold spell down the line with start with a huge Uk high as suggested by a couple gfs ensemble members but still looking pretty phenomenal in terms of prospects at this point in the year and anyone who is angry or upset has far too high expectations. 2010 was a one off.

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6 minutes ago, Steve Thexton said:

FV3?? guys for us mere mortals 😕

 

FV3, stands for Finite Volume Cubed, is the parallel version of the GFS, expected to take over in Jan 2019, it verifies well and we like it if it suggests snow.  Seriously, it is a significant upgrade to the US weather model.

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27 minutes ago, Mike Poole said:

Think it is time to call the FV3 as in the slider category, here T162:

image.thumb.jpg.6732043ba098fa02253aaa7b71c115bd.jpg

And it turns out I have made a complete Horlivka of a prediction. .

What on earth is a Horlivka?  I typed Horlicks! 

FV3 didn't slide, here T204:

image.thumb.jpg.4e3767dacc99e21a534ae7b86d571640.jpg

We await the ECM...

Horlivka is a city in Ukraine. 

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More information about the Finite-Volume-Cubed model can be found here, 🙂 

https://www.gfdl.noaa.gov/fv3/

Some people refer to it as the GFS Parallel. 

Must admit, found Mike Poole’s explanation with the part about snow, rather amusing! 

Edited by DiagonalRedLine

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Thank you Ed, Mike & Mucka, very helpful of you all. Definitely bring it on if it 'accurately' and regularly suggests snow!

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Since we’re back on the topic I think I will expand on what I said before.

In my experience with a continental flow I generally find the following conditions are the most important for a good chance of  precipitation to fall as snow. 

Dew point below 0°C 

T925 below 0°C 

T850 below 0°C (<-2°C preferable). 

T2m below 4°C 

500-1000 thickness can usually be ignored. 

 Wind off-shore if near coast. 

Light surface winds and heavy precipitation give you a great advantage and sometimes  a little leeway beyond the above margins. 

If T950/T925/t900 is below 0 but T850/T800 is not then ice pellets/freezing rain/rain will result depending upon the depth of the frozen boundary layer. 

 Also bear in mind the continent is not yet very cold so this method might not work at this time of year, however I am sceptical as to whether this will make much difference. I suspect it would only affect the very bottom of the boundary layer up to say 950 mB. 

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4 minutes ago, feb1991blizzard said:

Yes, i was just thinking the FV3 in deep FI was looking a bit Jan 1987ish  -  only a teeny weeny bit though.

Getting the perfect synoptics in the UK is like baking a good cake, we usually lack the ingredients, but right now they are all there and for the taking, it's not just hints and clutching at straws for something to turn up. Will we have something really tasty turn up by early December, It seems to me that we are in a far better position this year for something special. November is pushing it a bit for a decent cold spell, but by early December its definitely game!

Come on ECM, you can come out trumps!😮😉

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ECM T 120 is OK, I think UKMO was better, now all eyes on THAT low out west...

image.thumb.jpg.24c45e8a969bbb8f565ced1ecbbefd6c.jpg

Edit, T144, going under

image.thumb.jpg.04fe2751cc64a362e688b6acba26d71e.jpg

Edited by Mike Poole

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Really good 144h that low looking more stretched.

Capture.thumb.PNG.958622a827252afdcdeedc9930d925d6.PNG

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Am gona stick my neck out and say this is gona end up like gfs regardless of everyones excitement on the 120 and 144 hour chart!!watch that low turn into a football lol!!

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3 minutes ago, shaky said:

Am gona stick my neck out and say this is gona end up like gfs regardless of everyones excitement on the 120 and 144 hour chart!!watch that low turn into a football lol!!

No football on ECM T168, in fact I'm struggling to think of a game you could play with an object that looks like that!

image.thumb.jpg.8cb6a025ad083a13e582c5ad0a6b732f.jpg

 

Edited by Mike Poole

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The ejection of this shortwave is crucial, to me it looks further North than the 0z although cant put my finger on why but i still think it could turn out to be a decent run despite that.

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