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Model output discussion - here comes the beast!


Paul
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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Posted
  • Location: Hampstead / Cambridge
  • Location: Hampstead / Cambridge

96hours away people. Good start to the 18z runs from the Icon...

5A0FC0F6-F5D7-4991-8E38-279B720EEE7D.png

High further north, cold air pool further westward by about 6hrs. Marginally better wind angle. Decent improvements even by 108.

here is 120 on 12 (first chart) vs 18

BE892320-47B6-4140-8641-B5B4C4CEAEE2.png

F30485C1-4E60-4266-9A60-B893550DF201.png

Edited by ITSY
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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
17 minutes ago, Nick L said:

The EC is usually fairly keen to kill off shower activity as it trundles inland. Will be interesting to see the shower activity on the UKV and Euro4 over the coming days.

I would have thought that more strength in the sun as we approach early March may provide enough shallow heating above the ground to support some convective development inland as well - given how steep the lapse rates will be, something the models may not simulate well - through experience of seeing no ppn shown inland by a model but showers still popping up.

 

Edited by Nick F
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Posted
  • Location: Wirral, Merseyside
  • Weather Preferences: Snow & Thunderstorms
  • Location: Wirral, Merseyside
2 minutes ago, ITSY said:

96hours away people. Good start to the 18z runs from the Icon...

5A0FC0F6-F5D7-4991-8E38-279B720EEE7D.png

High further north, cold air pool further westward by about 6hrs. Marginally better wind angle. Decent improvements even by 108.

Yes 12z on left 18z on right :good:

iconnh-0-120.thumb.png.4486aa51c2ff278b416a17da6945d517.pngiconnh-0-114.thumb.png.f3d96ebefa66ff6bf3a25b09446d1406.png

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Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL

ICON has cold uppers ploughing into the uk on Sunday, earlier than its 12z run

90D77BDF-E9A6-4C0E-ACA6-82BB47319408.thumb.png.27ed0714b736f57a9dd375652a622c50.png04B0BA4D-94DC-48BC-99B4-550B41CC1EDA.thumb.png.0b3c5313c7809193902c78ddce8e1cea.png

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Posted
  • Location: cork Ireland 80m ASL
  • Weather Preferences: severe weather, tornadoes,intersting synopsis ,snow
  • Location: cork Ireland 80m ASL
3 minutes ago, Nick F said:

I would have thought that more strength in the sun as we approach early March may provide enough shallow heating above the ground to support some convective development inland as well - given how steep the lapse rates will be, something the models may not simulate well - through experience of seeing no ppn shown inland by a model but showers still popping up.

 

I  thought the lack of moisture would negate the laspe rates , surface thermals ? 

Edited by rory o gorman
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Posted
  • Location: Staffordshire moorlands 252m asl
  • Weather Preferences: Frosty and fresh
  • Location: Staffordshire moorlands 252m asl
1 hour ago, Nick L said:

I'll add to this, it will all depend on what the ratio of liquid water to snow ratio these maps are using too. Dry snow will put down about 3 times more than wet snow for the same equivalent of water.

question for you @Nick L 

is there any type of chart/graph that i can look at that will show this or is it a case of now casting

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Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire
3 minutes ago, Nick F said:

I would have thought that more strength in the sun as we approach early March may provide enough shallow heating above the ground to support some convective development inland as well - given how steep the lapse rates will be, something the models may not simulate well - through experience of seeing no ppn shown inland by a model but showers still popping up.

 

Yep, already been seeing daytime convection over land in the last week or two, and that's without the aforementioned ridiculous lapse rates. Will certainly be a learning curve for how the models deal with it.

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Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire
Just now, moorlander said:

question for you @Nick L 

is there any type of chart/graph that i can look at that will show this or is it a case of now casting

Can't say I know of such a thing unfortunately, if anyone does it would be useful. The figures I quoted are a rough rule of thumb!

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
1 minute ago, rory o gorman said:

I thought have thought the lack of moisture would negate the laspe rates , surface thermals ? 

Usually there is enough moisture aloft in our maritime climate to support high based convection with warming from below, even if the continental surface flow has dried out inland from the North Sea.

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
2 minutes ago, Nick F said:

I would have thought that more strength in the sun as we approach early March may provide enough shallow heating above the ground to support some convective development inland as well - given how steep the lapse rates will be, something the models may not simulate well - through experience of seeing no ppn shown inland by a model but showers still popping up.

 

Agreed, I can remember a few past examples in which a predicted (by models) dry day was interrupted at least once by those magnificent sort of billowing yet at the same time wispy clouds, leading to a sudden transition at ground level from clear to snowing readily. 

Admittedly some of those may be from my dreams but I assure you it has happened in reality at least once this century :D.

So yes, should be lesson one of global model reading really; don't trust them to handle convective showers.

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Posted
  • Location: Grays, Thurrock
  • Location: Grays, Thurrock
7 minutes ago, ITSY said:

96hours away people. Good start to the 18z runs from the Icon...

5A0FC0F6-F5D7-4991-8E38-279B720EEE7D.png

High further north, cold air pool further westward by about 6hrs. Marginally better wind angle. Decent improvements even by 108.

here is 120 on 12 (first chart) vs 18

BE892320-47B6-4140-8641-B5B4C4CEAEE2.png

F30485C1-4E60-4266-9A60-B893550DF201.png

looking very good. Italian low is slightly further north and more energy going it into from the lows in the Atlantic. I think its possible we might see more energy go under.

can you imagine the chaos if there was stronger Italian low increasing the pressure gradient/wind speeds and driving the sub -18 uppers into us.

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Posted
  • Location: cork Ireland 80m ASL
  • Weather Preferences: severe weather, tornadoes,intersting synopsis ,snow
  • Location: cork Ireland 80m ASL
1 minute ago, Nick F said:

Usually there is enough moisture aloft in our maritime climate to support high based convection with warming from below, even if the continental surface flow has dried out inland from the North Sea.

0 /15 c spread will be quite interesting to see the the results of LCL ect  .Forecast Soundings will come into reach soon certainly worth a look over. 

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Posted
  • Location: Hampstead / Cambridge
  • Location: Hampstead / Cambridge
4 minutes ago, pages said:

looking very good. Italian low is slightly further north and more energy going it into from the lows in the Atlantic. I think its possible we might see more energy go under.

can you imagine the chaos if there was stronger Italian low increasing the pressure gradient/wind speeds and driving the sub -18 uppers into us.

Interesting observation - the low in question is actually much further north on the 18 ICON than the 12 GFS, though even by +48 it is slightly further north on the GFS (18z run) this evening. It would certainly accelerate the cold westward by strengthening the mean easterly across Central Europe, which would be no bad thing at all for early cold onset. Just another thing to look out for...

Edited by ITSY
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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

GFS possibly a little further north at T66, 18 and 12:

gfs-0-66.png?18

gfs-0-72.png?12Or maybe faIrly close on second look.

Edited by Mike Poole
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Posted
  • Location: Hatfield Peverel near Chelmsford Essex
  • Location: Hatfield Peverel near Chelmsford Essex
8 minutes ago, Dbarb said:

 

Edited by Dbarb
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Posted
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast
  • Weather Preferences: Severe Storms and Snow
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast
1 minute ago, blizzard81 said:

Lovely 120hr fax chart 

fax120s.gif

Looks like an East/South Easterly?

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Posted
  • Location: Rotherham
  • Location: Rotherham

The trend this evening so far is to push everything further north and West again. I wonder if the models have under estimated this because there's definitely momentum to build the cold in much quicker again!

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Posted
  • Location: Tarves, Aberdeenshire, 86m asl
  • Location: Tarves, Aberdeenshire, 86m asl
2 minutes ago, Neilsouth said:

Looks like an East/South Easterly?

Is that a trough on the 120h fax to the east of Scotland?

Edited by howham
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