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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

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1 minute ago, Reverse Zonality said:

GFS 18z has the low a little further north and west compared to the 12z

18_129_mslp850.png?cb=398

Not great as it moves more into line with the ECM 12z in bringing milder uppers from the south a little quicker on Friday. Just one run and all that!

Much further west on this one. I do wonder what will happen if it ends up moving west quicker before it develops. Its been further west on the last 2 runs. 

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GFS at T138' well the idea of the two mini lows following behind look nice I guess, but the whole thing is 200 miles too far north, at least:

gfs-0-138.png?18

Meanwhile, ICON cold until the end of it's short run, here at T108 and T120, but where is the low going? That's still the question.

icon-0-108.png?24-18

icon-0-120.png?24-18

Over to the graveyard shift for further elucidation.

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2 minutes ago, Reverse Zonality said:

GFS 18z has the low a little further north and west compared to the 12z

18_129_mslp850.png?cb=398

Not great as it moves more into line with the ECM 12z in bringing milder uppers from the south a little quicker on Friday. Just one run and all that!

I think GFS is slowely backing from this idea as it tries to forecast the Jet stream... The low is much weaker in this run and if that trend continues the low will most likely be killed off by Monday/Tuesday GFS runs 

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Just now, c00ps said:

Which is it? ?

6955551A-3CC6-4DF7-8254-D979F1602634.png

Both are correct.  The lows are having a tougher time breaking through the block, yes, but their orientation actually means that milder air penetrates faster from the south-west.  

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28 minutes ago, Ayrshire weather said:

Ohh.... Just leave this here then! 

Screen Shot 2018-02-24 at 22.13.03.png

Well you can’t get less cold air and precip in without having a snow event so it’s hardly rocket science. if the morning output is on the same page as the 12z’s then we won’t see this story changing but suspect Exeter will reference the chance of a less cold incursion being possible next weekend in their further outlook. The tv forecasts will just concentrate on what comes before as this is the real story for the here and now. 

 

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Wouldn't take much of a southerly correction to keep colder uppers over most of the country. Our first low stalls out to the west before being absorbed by a second low to it's SW. Who's to say the first low struggles more against the cold than is currently being modelled, meaning there is less of an influence to pump milder uppers towards the UK? It's not as if the Atlantic is 'waking up' in this run, after all. Fascinating model watching!

18_237_mslp850.png?cb=667

Edited by Reverse Zonality
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Mad Friday back on the 18z blizzards for most of the country, NE and Scotland staying in the cold for longer.

What's not to like ends with a bang not a whimper, probably won't happen but I'd take it. Extended longevity of cold cannot be expected at this time of year... 

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43 minutes ago, Matthew. said:

Exceptional. Never seen this for real life before 

7D707182-5787-4464-991F-478586FEA6A3.jpeg

This is why I doesn't sit well as to how the uppers can go from -16oC on Wednesday to close to 0oC by Thursday evening. That is some dramatic warming  :o

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On Saturday the 0C line (850hPa) is roughly around the Midlands. Next Thursday the 0C line is........ roughly around the Midlands. The north stays cold as a result. 

Spring may be just around the corner but it is more reluctant to peep its head around and say hello than some of you think.

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3 minutes ago, Snowbound said:

This is why I doesn't sit well as to how the uppers can go from -16oC on Wednesday to close to 0oC by Thursday evening. That is some dramatic warming  :o

Of course it can happen, 2010s final cold spell ended in similarly dramatic fashion with the low 850s being swept away quickly from the west.

That said the 18z away from the far south, never gets that warm.. certainly south of Scotland it's too marginal, but it's still chilly. It's almost like central parts of northern England are in some kind of purgatory.. there would be a lot of rain.

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2 minutes ago, SP1986 said:

Of course it can happen, 2010s final cold spell ended in similarly dramatic fashion with the low 850s being swept away quickly from the west.

Though it was an upper warm front from the east that brought drizzle 1987 fizzled our as well despite a forecast for a longer spell. Would be interested to see how Mogreps is looking and whether that is wavering at all. Interesting that 18gfs holds the front out west another trend maybe

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Still expect the broader western trough to do all the backing west upon interaction with the cold pool while the eastern one splits away east... but confidence has undeniably taken a knock this evening.

Extraorindary swing by the models but plenty of time for a reversion or further, time which just so happens to be largely occupied by exceptionally cold conditions with widespread snow chances.

Could be worse ;)

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45 minutes ago, tinybill said:

i have just witnessed  one  of the scary  weather  forecast ever  on the  bbc news  24  if any one recorded it i dont know how please put it on here it like the day after tomorrow the end of  the week will make your hair go up on your neck  and this  no ramp

Yeah it was an interesting one with "coldie" Tomasz.Looks like snow showers starting midday onwards on Monday and Monday-Weds looks like showers will become widespread with some prolonged snowfall although he did stress some areas will get more than others(graphics showed some could get 20cms+ while others 3cms or less.Friday could be a possible blizzard for Southern Britain but did stress alot of uncertainty.Whilst models as i write this post have much of South in milder air by end of week the BBC graphics didnt indicate this but Friday is so far away in met terms we wont i feel know  until Tuesday night how far North this low pressure will go.I am just looking forward to the next 48-72 hrs unfold and then take it from there.Lets just enjoy this epic cold for the time of year and hope this ST cold snap turns into a cold spell and this time next week we will still be enjoying it:cold::)

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7 minutes ago, inghams85 said:

Can't tell you how i know but the MOGREPS moves the low across the channel as a much weaker affair with blizzards on the Northern edge. This is the basis of the Met forecasts. The other lows follow on the same track hence the mention of continued easterly winds following week. Calm down people. 

fax120s.gif.b45a07e2d33b36203ca882bca4de

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4 minutes ago, inghams85 said:

Can't tell you how i know but the MOGREPS moves the low across the channel as a much weaker affair with blizzards on the Northern edge. This is the basis of the Met forecasts. The other lows follow on the same track hence the mention of continued easterly winds following week. Calm down people. 

Thanks - but is this still valid for the latest output or from earlier today when the Met forecasts were formulated? The main models seem to have shifted unfavourably for coldies after the 12z runs.:)

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GFSOPUK18_141_5.png

 

I agree with Steven Sussex, its only the far southern counties that climb up to 5 to +7oC... North of the M4 its close to freezing or below. So.. if that big low does track up central western areas there will sure be a lot of snow.  :o 

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