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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:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

We also have a special post SSW cold spell discussion open here:
https://www.netweather.tv/forum/topic/89358-ssw-related-cold-spell-will-it-wont-it/

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

Posted Images

The race between the omega block and the second deep cold blob.

We are seeing some differences now to the nw , note the ECM and GFS split a shortwave between T120hrs and T 144 hrs which runs ne towards Iceland .

The UKMO doesn’t do this and has the cleaner evolution which allows the high a better orientation to advect the cold westwards.

 

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4 minutes ago, Mike Poole said:

Hmmm, spicy

ECM1-216.GIF?20-12

Wow. That would definitely be quite fun,

 

Would like to see the precipation charts as that low crosses the country as well. A low propping up around this sort of time seems to be a recurring theme in the recent model output.

 

Edited by Deep Snow please
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Just now, Nick L said:

Another thing to consider is that dry snow puts down more than wet snow for the same liquid equivalent. With wet snow it's typically 10:1, dry snow can be around 30:1.

What’s the top out figure on the piste by Wednesday Nick? 

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3 minutes ago, radiohead said:

192 looks great on the ECM. The delay in colder uppers was only 24 hours.

ECM0-192.GIF?20-0  ECM1-192.GIF?20-0

Think some may argue that the coldest uppers get delayed however the -12hpa does come in before a slight mixing out because of that shallow low and shortwave but all that said, another very cold run indeed.

Details will still change and it will get much colder, the question will be how much instability will there be? Sadly that is something we won't know for a while yet.

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Yeah the 12z ECM is full on snow at 168hrs, great set-up.

I have to say I think the evolution on tonights 12z ECM is a good one. I'd be very surprised if we didn't get a LP system form with such unstable large lapse rates and instablity in the north sea. I expect that to become a trend. (The ECM has been toying with it over the last few runs.

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1 hour ago, nick sussex said:

I’m not telling people not to worry . I’d be on the Prozac already or some sedative to cope ! :D

All I’m saying is let’s get the first cold wave nailed down , so fair enough worry about that but the pattern past that first cold is dictated by what the eventual solution is that verifies before T144 hrs.

The are a variety of options on the table.

Indeed. ECM show's that even with a lower lat high, so long as the retrogression is quick and clean then the high will be far enough West to prevent it cutting off the cold feed.

All in all though I would still prefer to see the high modelled further North :D

ECH1-192.GIF?20-0gfsnh-0-192.png

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After the hiccups of the APERGE and the GFS operational 12z earlier . The ECM is a perfect run for coldies. Get the snow in, then very cold air afterwards, and then further reloads of snow. A snowfest.

IMG_1701.GIF

IMG_1702.GIF

IMG_1706.GIF

IMG_1705.GIF

Edited by pandit-scholar
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Because of the shortwave discrepancy to the nw at T120hrs and T144hrs I’d be wary of taking any detail past that point with much confidence .

Wait till the outputs agree on that as it does have a bearing on the high set up.

 

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this run looks epic for snow but it don't look right between 144-216

the vortex drops a small low into Svalbard that just sits there between the 2 blocks. think it would more likely that vortex moves round the block or drops a larger lob into scandie at 192 giving north easterly.

ECH1-168.GIF?20-0

ECH1-216.GIF?20-0

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Not really sure why people are concerned with this ECM run:

Easterly flow from tomorrow for the foreseable dropping dew points

Sunday onwards sees 850hPa temps dropping to below -10C with a sustained easterly feed embedding the cold over U.K. 

With those 2 features in place, I wouldn't be surprised to see snowfall with 850hPa temps at -2C/-3C (if the flow is from the continent). 

Given that the ECM has the shortwave moving east to west (maintaining the flow from the continent) and 850hPa temps of less than -8C, anything that falls from the sky will be snow.

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2 minutes ago, nick sussex said:

Because of the shortwave discrepancy to the nw at T120hrs and T144hrs I’d be wary of taking any detail past that point with much confidence .

Wait till the outputs agree on that as it does have a bearing on the high set up.

 

Agreed, I'm feeling very confident in the intial thrust of the cold onthe 25-26th,it is possible pressure and forcing won'tbe as good the further north you go but -12C at the very least should be more than enough to crank open the north sea fires, even at higher presures, though convection would probably be somewhat shallow.

After that, just about anything can happen, from the block slipping SW and slipping in a highly moderated northerly flow (with uppers back towards 0C) right through to full blown blizzard set-ups and monster northerlies/easterlies. All on the cards post 168hrs.

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