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Model output discussion - here comes the beast!

Message added by Paul

Please only post model discussion in this thread 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:

We also have a special post SSW cold spell discussion open here:

Thank you!

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Early guidance forewarning of next weeks weather was issued earlier on, and this has been further enhanced with extended outlooks in bulletins. AFAIK (comms not being my area) public agencies and majo

Come on those looking for the breadown before the major cold and snow has begun You will be very lucky if that is the correct word to see this in ANY winter in the rest of your lives I would sugg

Microscale detail absorbing an awful lot of attention on here, when in reality it is a waste of emotion. The macroscale pattern is now fixed - it will not change significantly now for the start of nex

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10 minutes ago, Reverse Zonality said:

The only thing I can suggest is you check the ensembles on ECM and GFS. There is huge spread after Thursday which is why jumping to conclusions after every op run is a pointless exercise. 


the voice of reason . . . 

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I feel like we're giving a little bit too much attention to the 850hPa temperatures for the event on Friday. The colder uppers seem to be easily pushed aside by the low, but with 4-5 days of temperatures struggling to get above freezing and harsh night time frosts the boundary layer is going to be extremely cold.

Whilst the 850hPa temps could possibly become "mild" in comparison to what we will experience this week, the warmer air associated with the low will probably be pushed aloft to an extent with the surface temperature staying around or below freezing. If not snow, counties in the far south would probably see some freezing rain.

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2 minutes ago, Frosty. said:

There's still tons of uncertainty from the end of the week but I think the models are backing away from the milder trend compared to last night and what an incredibly wintry week ahead..I'm so excited!:):D:cold:

Yes Frosty, I agree. Just flicking through the ensembles for next weekend shows the uncertainty, some just bring slightly colder air meaning copious amount of snow nationwide. You can see why some weather forecasters have a serious look in their eye while presenting atm! 

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1 minute ago, Steve Murr said:

Just the first signs that the GEFS not so keen to move the warmth North- More of an attempt North before stalling & moving East - PTB 2 for example...

As highlighted though it will probably go to T24-48 etc


I think the NAVGEM has got it right ! :D


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06z Short ens for London showing it staying very cold until around Thursday then the control, op and mean all agree on slightly less cold air for the weekend ground temps on the other had will take longer to respond


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Meanwhile back at the ranch.......

Rain/Snowfall EURO4 Tu 27.02.2018 00 GMT

Rain/Snowfall EURO4 Tu 27.02.2018 06 GMT

And that's before the second push of really cold and the tightening of the isobars


And yes that is Arpege ,which for the sake of your sanity,is a good bet as it doesn't run into la la land and probably nearer the mark for the METO 

Edited by winterof79
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Full London ens on the 06z a fraction lower than the 00z around the 7th obviously seeing a repeat of the -15's is probably unlikely but still on the chilly side





Edited by Summer Sun
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Morning all :)

No detailed analysis from me as Mrs Stodge has other plans for my Sunday.

Just a few comments on the output I'm seeing this morning:

1) The threat of a west-based negative NAO has always been there - I was talking about it at the beginning of last week. We needed a much stronger HP profile than we are now seeing to firmly the deflect the Atlantic LP more east and south. This is how the 2010 cold spell ended (and in fairness was superbly modelled by GFS which nailed the evolution consistently from T+384 down).

2) Bringitback62-63's excellent summations did take me back to March 2013 when GFS consistently modelled the return of warmer air from the south west for it to fail time and time again. I'm less convinced of the parallels this time but it's worth bearing in mind.

3) Many have agonised in the past week over the exact positioning of the cold pool which varied by 150-200 miles from run to run - now we are agonising over an LP where the scale is similar. As others have said, exact tracks and trajectories won't be clear until Wednesday but the NAVGEM solution would, I suppose, be many people's preference. I wouldn't be surprised to see less cold air cross the country over next weekend.

4) It's unrealistic to expect -12 uppers to be over us for weeks - the coming 72-96 hours will be an exceptional spell for many (and a predictable disappointment for some) but inevitably it couldn't last and even if we had managed a seamless transition to a NE'ly (which never looked likely) there would have been an easing in the frigidity of the air.

5) Once again we are seeing signs of height rises to the east and north-east in far FI - not inconceivable we could have another Scandinavian HP by mid month and certainly one to watch. It's entirely possible while this week's cold may be the most severe, it won't be the last.

One thing is certain - more exciting and tense model watching this coming week as there has been in the past fortnight watching the cold spell evolve.

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15 minutes ago, Johnp said:

Wouldn't it be amusing if a combo of Icon and NAVGEM nailed this cold spell ?

I was thinking this before that the IKON really was the king of the models in preparation for this spell. Did someone say it was to do where it specialised in the atmosphere?

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