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Winter Model Discussion 12Z 09/01/13> The hunt for cold ?


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Posted
  • Location: Headington,Oxfordshire
  • Weather Preferences: Snow
  • Location: Headington,Oxfordshire

You can see thats already developing a distinct shortwave to the sw.

Thanks for posting these charts and the NAO Discussions as you do on on a regular basis, i'm still getting my head around them but getting there. Would this shortwave you talk about be a good thing for us? Cheers, Mark. biggrin.png
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Posted
  • Location: Dorset
  • Location: Dorset

Beware the gfs, 3 runs in a row does not make the gfs correct, if indeed gfs continues on its 06z theme scenario. Remember the ECM which was out of kilter for 2 runs.

Also a bad sat pass which derives the upper atmospheric data will linker in the system for 12-24 hrs I.e until the next pass.

IMHO this is what effects the ec and could be effecting the gfs this morning.

This isn't anything new, sat sweeps will be good or bad having better or worse coverage and special algos are ran to patch them up. Never at times of Shannon entro such as now the effects can be huge, e important thing is that we go with the models with the most cross model support.

Good luck and hope gfs is a stunner, selfishly for us in the sw.

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

forecasters are now beginning to drop more and more hints about a higher risk of snow into next week which is what most of us are hoping for after the mild wasteland that was christmas and new year, the models are firming up on a cold spell to start as soon as this weekend and then deepen into a more potent cold outbreak next week and beyond, it could be prolonged since the most substantial strat warming downwelling is still to come. Fingers crossed we get a Gfs 12z more like yesterday to get the snowball rolling and getting bigger and bigger by the time the ecm 12z roles out, by tonight we should at least have a better idea of the depth and longevity of the upcoming cold spell.

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Posted
  • Location: Devon
  • Weather Preferences: There is nothing more beautiful than a hoar frost.
  • Location: Devon

the the Shannon entropy

this link will keep you occupied for a while

http://www.bing.com/...Box&FORM=IE8SRC

What is entropy used to be a favourite on Met O promotion boards-I suspected it was because even the senior staff wanted someone to give them a simple accurate explanation!

My very simple explanation would have been: It's when the Supercomputer says WTF rofl.gif

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Posted
  • Location: Nymburk, Czech Republic and Staines, UK
  • Weather Preferences: Sunny and warm in summer, thunderstorms, snow, fog, frost, squall lines
  • Location: Nymburk, Czech Republic and Staines, UK

forecasters are now beginning to drop more and more hints about a higher risk of snow into next week which is what most of us are hoping for after the mild wasteland that was christmas and new year, the models are firming up on a cold spell to start as soon as this weekend and then deepen into a more potent cold outbreak next week and beyond, it could be prolonged since the most substantial strat warming downwelling is still to come. Fingers crossed we get a Gfs 12z more like yesterday to get the snowball rolling and getting bigger and bigger by the time the ecm 12z roles out, by tonight we should at least have a better idea of the depth and longevity of the upcoming cold spell.

Or the rapid return to mild next week, as the case may be. I don't know how anyone can claim to know what will happen next week with all the model uncertaintly going on. Could be another rerun of December coming up? Really hope not as I'm so bored of mild/cloudy/damp.

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Thanks for posting these charts and the NAO Discussions as you do on on a regular basis, i'm still getting my head around them but getting there. Would this shortwave you talk about be a good thing for us? Cheers, Mark. biggrin.png

No you dont want that shortwave developing in the southern USA heading ne in tow with the one already towards the ne USA.

You need a single low tracking ene towards Greenland.

On this point the latest NAM at 84hrs still doesn't back the earlier GFS 06hrs, thats the shorter mesoscale model.

You might get some residual energy later on but its important that the first shortwave phases with troughing in the west Atlantic before that happens.

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Posted
  • Location: Headington,Oxfordshire
  • Weather Preferences: Snow
  • Location: Headington,Oxfordshire

No you dont want that shortwave developing in the southern USA heading ne in tow with the one already towards the ne USA.

You need a single low tracking ene towards Greenland.

On this point the latest NAM at 84hrs still doesn't back the earlier GFS 06hrs, thats the shorter mesoscale model.

You might get some residual energy later on but its important that the first shortwave phases with troughing in the west Atlantic before that happens.

Thanks for the reply, Nick! good.gif That makes more sense now, Ta.

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

Very interesting 4 hours of model watching coming up. I do my absolute best to stick to means and not get carried away by the ebb and flow of op runs, but there is something curiously fascinating and attractive about throwing one's eyes into a thread that is guaranteed either to leave you banging the wall in frustration, jumping for joy over the top of your monitor or perhaps just gagging for more.

Having stared at the strat forecasts again I will throw my lot into the ring and declare that I expect to see blocking to the north maintained, but not quite the stellar ECM runs of yesterday. Snow anytime from Sunday to the end of next week a definite possibility on the back of easterlies brought about initially by the weekend's undercut. Further out I see a potent north / north easterly on the cards as the high drifts NW and remnants of the vortex drops in behind, but there is a lot of drama to be had before we get so far out...

Having said that this is the models we are talking about: they make gibbering idiots out of us far too often!

Edited by Catacol_Highlander
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Posted
  • Location: NW London
  • Weather Preferences: Snow, Thunderstorms
  • Location: NW London

What does the SSW have to do with that shorwave on the 6gfs. Surely that is independent of the SSW? I've heard it.mentioned a few times.

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Posted
  • Location: Norfolk
  • Location: Norfolk

What does the SSW have to do with that shorwave on the 6gfs. Surely that is independent of the SSW? I've heard it.mentioned a few times.

It doesn't. The shortwave is just a disrupting shortwave which, if modelled correctly, could ear us back to a milder outlook.

SSW is a potential boon for cold prospects as it will ear to te cold flooding out like an overfilled glass. However, it is not a joker and we don't get to play it where and how we fancy. It might do us no good at all.

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Posted
  • Location: OSLO, Norway
  • Weather Preferences: Snow, Storms, Heat, Thunderstorms
  • Location: OSLO, Norway

What does the SSW have to do with that shorwave on the 6gfs. Surely that is independent of the SSW? I've heard it.mentioned a few times.

It has absolutely nothing to do with the development of the shortwave as far as im aware.

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Posted
  • Location: Rogerstone/Risca South Wales
  • Weather Preferences: Blizzards in winter Hot and sunny in summer...other is simply boring!!
  • Location: Rogerstone/Risca South Wales

Afternoon all .........new to this model watching game and I know i wont be in for as much fun as yesterday!! But I can hope!!!!

What time does the drama begin? Gfs (12z)?? I am aware the ECM 12z kickS off at 6pm

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Posted
  • Location: OSLO, Norway
  • Weather Preferences: Snow, Storms, Heat, Thunderstorms
  • Location: OSLO, Norway

Afternoon all .........new to this model watching game and I know i wont be in for as much fun as yesterday!! But I can hope!!!!

What time does the drama begin? Gfs (12z)?? I am aware the ECM 12z kickS off at 6pm

..3.30

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Posted
  • Location: Broxbourne, Herts
  • Weather Preferences: Snow snow and snow
  • Location: Broxbourne, Herts

Very simple (if slightly OT) question.

Are the models more reliable in summer or is it the same?

Just the fact that there is no expectation upon them to distinguish between precipitation being rain or snow means there is certainly a perception of them being more accurate.

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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20

First pertient 12z model output - the mighty GME!

gme-0-72.png?12

gmefr-1-72.png

Some snow risk possibly for parts of the Midlands for Saturday lunchtime?

Edited by mulzy
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Posted
  • Location: Siston, Bristol 70m ASL
  • Location: Siston, Bristol 70m ASL

or mass suicide!!!!

Its a gamble i guess what i think id like to see some model agreement soon, so much still changing in short term.

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Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

I suspect an upgrade in the shorter term, it was mentioned earlier that the NAE (high res) model had much colder uppers arriving on Friday than the big 3 (-7 on the norfolk coast as opposed to -3/4). That's if that model is in anyway reliable. This could also have impact on the longer term perhaps if the models have underestimated the initial scandi high for the weekend.

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Just before the GFS starts to roll out the latest guidance from NOAA goes with the ECM ensemble mean for the pattern in the USA.

That includes the forecasters having looked at all the 00hrs runs aswell as the GFS 06hrs horror show!

Lets hope the GFS is listening, we'll know in about 15mins! Shredded nerves await!

Edited by nick sussex
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Posted
  • Location: NW London
  • Weather Preferences: Snow, Thunderstorms
  • Location: NW London

Just before the GFS starts to roll out the latest guidance from NOAA goes with the ECM ensemble mean for the pattern in the USA.

That includes the forecasters having looked at all the 00hrs runs aswell as the GFS 06hrs horror show!

Does that mean they don't think that shortwave is correct?

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Posted
  • Location: Rogerstone/Risca South Wales
  • Weather Preferences: Blizzards in winter Hot and sunny in summer...other is simply boring!!
  • Location: Rogerstone/Risca South Wales

cheers guys .....anybody have any gut feelings on this GFS run....?? I noticed that weather forecast on city forecasts on other weather sites are showing increases temps to 8 c in my area, after monday ...could this be due to this mornings GFS run ? They are in all honesty pretty useless after 3 days .......

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Posted
  • Location: Middle Wallop, Hampshire SO20
  • Weather Preferences: storms and extreme weather
  • Location: Middle Wallop, Hampshire SO20

perhaps the mods should post the link to the moaning thread before the model output images hit this forum good.gif

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Posted
  • Location: Wakefield, West Yorkshire
  • Location: Wakefield, West Yorkshire

The stratosphere forecasts are produced by the same models.

They have all of this data factored in.

It seems to be a growing misconception that they wait till a SSW occurs and then suddenly feed all this data in, it is there all along!

I'm not sure that's correct buddy. Here is a quote from Liam Dutton's recent blog:

"Most weather computer models tend to focus on what happens in the lowest part of earth’s atmosphere (the troposphere) because this is where weather happens.

As a result, they are not very good in taking into account sudden stratospheric warming events as they occur so much higher up. Also, the link between stratospheric warming and blocking high pressures is a relatively new discovery in meteorology, with research ongoing.

The Met Office has tackled this problem by developing an additional model, called GloSea4. It takes into account what is going on higher up in the stratosphere in an attempt to better predict the effects it may have on the weather lower down."

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