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Model Output Discussion 19th January 2014-18z onwards.


phil nw.

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Posted
  • Location: Sowerby Bridge, West Yorkshire
  • Weather Preferences: Click on my name - sorry, it was too long to fit here......
  • Location: Sowerby Bridge, West Yorkshire

75% of ensemble members with notably greater amplification at 120h, some remarkably so. One extra on a few is a dartboard low zipping through central UK at around the same time, could be nasty if that verifies (as below).

 

Posted Image

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Posted
  • Location: West Sussex
  • Weather Preferences: Extreme cold & snow
  • Location: West Sussex

 Of course not but would you have posted the same comment had it shown mild? Surely it is as likely as most other GFS 'default progressive' low res output of late?

Absolutely mate - but as we all well know mild / zonal is the usual British winter setup (Check Koeppen Climate zones) so unfortunately does tend to verify more than cold setups.

Anyway let's hope we do get a great freeze up in February although I do remember folks getting fed up last March because it was too cold for too long!! LOL

Edited by Purga
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Posted
  • Location: Sunderland
  • Weather Preferences: Hot Summer, Snowy winter and thunderstorms all year round!
  • Location: Sunderland

For the benefit of lurkers on here, don't take the GFS precipitation charts literally after 192 hours. The resolution decreases and therefore the grid sizes also increase which makes it look like there will be far more rain / snow than us actually going to be the case. Obviously even before this they are not useful really at long range anyway. In essence they can be amusing to look at but even if the Synoptics were bang on there would be much less snow than these charts tend to show.

Phew, that's a relief! I don't know if I could put up with all that green & pink stuff falling out of the sky, not to mention those lancing green lines striking the ground on those metociel charts......could be worse though, could be yellow, hmm yellow snow....no, let's not go there ......is that literal enough for ya? Posted Image

 

I'll fetch me coat Posted Image

Edited by ajpoolshark
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

I'm concerned she may have been turned, its like Homeland meets the Snow Haters! Hopefully she's still okay and hasn't been to the reprogramming centre at Exeter where they teach you the correct facial expressions and use of language when forecasting snow! Joking aside there is a window of opportunity with the Arctic high on the scene, if we can just get a clearance upstream of that energy and the block can extend further sw then theres a chance of some snow.

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Posted
  • Location: Solihull, WestMidlands, 121m asl -20 :-)
  • Weather Preferences: Cold and Snow -20 would be nice :)
  • Location: Solihull, WestMidlands, 121m asl -20 :-)

In FI ...you see a very good example of cold blocking, In looking at the surface pressure chart below you would think the atlantic would push East, with ease

 

Posted Image

 

Until you see the cold 850hpa temperatures that are just to the East of the UK,

cold air is denser than warm air, so the warmer air finds it a lot harder to push through the block HP.

 

Posted Image

Most on here know this, thats why we all love a good Easterly because when the cold air is in place, in can take a long time to get rid of, if not weeks.

And when the atlantic tries to push East against the cold blocking, HERE in the UK we can have some very good snowfalls, as you can see below.

 

Posted Image

 

Just a note, this is a simple guide and just for folk that don't fully understand what blocking is about..... hope it helps.

Edited by Dancerwithwings
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Posted
  • Location: East Anglia
  • Location: East Anglia

By Monday, UKMO-GM has snow showers advecting well inland on westerly flow across e.g. W Country, M4 corridor, Wales etc. As I mentioned yesterday, the unusually chilly characteristics of the westerly flow - at least, as currently progged - looks more likely to bear wintry ppn than otherwise might be the norm for late Jan. One to watch....

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Posted
  • Location: Ribble Valley
  • Location: Ribble Valley

Not quite true, even with a raging PV over Canada/Greenland you can still get heights close enough to the UK to bring cold weather. Just in this case we are literally just a couple of hundred miles away from very cold surface conditions and potential battleground events.

Not to say that won't change. The Arctic high looks set to reinforce that high to the north east, could it push west? Could we get a link (even briefly) between the Atlantic and arctic ridges. Both of those could push things in our favour.

Oh well with the block to the north east continuing to exist, my sanity levels will continue to drop to new depths (currently sub zero by my last check).... standard Posted Image

It may not be quite true but it's the obvious scenario going forward. Over the last 10 days or so we've seen a slight change in the overall NH pattern but the end result differs little from what we've endured thus far. Yes we have a strong block to our east and yes we have seen some disruption to the PV which has resulted in a more positive pattern for colder shots, but what we are still not seeing is a pattern conducive to a long lasting cold spell anytime soon and nor are we guaranteed one regardless of Stratospheric warmings and the MJO. Edited by Sceptical Inquirer
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Posted
  • Location: Wellseborne, Warwickshire
  • Weather Preferences: Southerly tracking low pressure in winter. Hot and thundery in the summer
  • Location: Wellseborne, Warwickshire

By Monday, UKMO-GM has snow showers advecting well inland on westerly flow across e.g. W Country, M4 corridor, Wales etc. As I mentioned yesterday, the unusually chilly characteristics of the westerly flow - at least, as currently progged - looks more likely to bear wintry ppn than otherwise might be the norm for late Jan. One to watch....

As nice as that that is to read Ian , it's stil nearly a week away and much can change , been a westerly flow its certainly unusual , but there is time for the cold to be downgraded nearer the time , because like you say the air is very much colder than a normal westerly . Let's hope it keeps up the snow signals
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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

Okay last post from me tongiht.

 

GFS ensembles 

 

NW England

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=232&y=37

http://www.meteociel.fr/cartes_obs/gens_display.php?x=232&y=37&run=18&runpara=0&type=3&ext=1

 

SE England

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=296&y=122

http://www.meteociel.fr/cartes_obs/gens_display.php?x=296&y=122&run=18&runpara=0&type=3&ext=1

 

A few days ago I was talking about needing the Scandi high to hang on and link up with the Arctic high because the jet was set to fire up again bringing an Atlantic assault with it and only the combined forces of blocking had a chance of deflecting low pressure into Europe - if that didn't happen we would likely be staring down the barrel at a full on zonal attack.

Thankfully it looks sure now that the Scandi high will hold on and link up with the Arctic high so that is phase one out of the way.

Phase two is not so clear cut as the models are unsure of how quickly to push low pressure through into Europe - we need to see that process happen more effectively across the output.

Phase three is the Atlantic ridge (amplification upstream) which ties in with phase one in that it can link up with high pressure to the NE deflecting further lows SW of the UK in an ideal scenario or in a middle ground it can be strong enough to hold up low pressure so it does not phase with the trough over the UK which would give us further chances or worse case there would not be much amplification and the next low would phase with any lingering trough over the UK - not game over but limited prospects.

 

So of those 3 major phases toward a cold pattern my guestimates for the current MO predictions are;

phase 1 looks 95%

phase 2 looks 50%

phase 3 looks 25%

 

Not to be taken too literally but you get the gist and lets hope those percentages on phase 2 and 3 firm up tomorrow.

Edited by Mucka
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In FI ...you see a very good example of cold blocking, In looking at the surface pressure chart below you would think the atlantic would push East, with ease

 

Posted Image

 

Until you see the cold 850hpa temperatures that are just to the East of the UK.

 

Posted Image

Most on here know this, thats why we all love a good Easterly because when the cold air is in place, in can take a long time to get rid of, if not weeks.

And when the atlantic tries to push East against the cold blocking, HERE in the UK we can have some very good snowfalls, as you can see below.

 

Posted Image

 

Just a note, this is a simple guide and just for folk that don't fully understand what blocking is about..... hope it helps.

 

All it takes is a mild airmass moving in and the cold will be gone faster than you can say Bob's your uncle, nothing inherent about cold air itself that makes it hard to shift, look at the USA when they had that bitter cold a few days ago with temps down to -40c, in places temps rose by 30-40c in little over a day. A good strong block (high heights, preferably yellows and oranges though lower ones can work but more tricky) in the right place and/or a weaker Atlantic should keep the cold in place and hopefully send some our way. Got to get there first but many hurdles to jump over yet. I'd love a good blizzard...

Edited by Bobby
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Posted
  • Location: Wellseborne, Warwickshire
  • Weather Preferences: Southerly tracking low pressure in winter. Hot and thundery in the summer
  • Location: Wellseborne, Warwickshire

Not to be taken too literally (!!! Caution!!!) but here's modified UKMO-GM at T+144:Posted ImageScreenshot_2014-01-21-23-32-19-1.png

Ian have you saw the latest infamous gfs run?! Normally laugh it off but lots of support from its ensemble suit . Could the complete set bark up the wrong tree? Or the beginning of a trend?
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Posted
  • Location: Ribble Valley
  • Location: Ribble Valley

Not to be taken too literally (!!! Caution!!!) but here's modified UKMO-GM at T+144:Posted ImageScreenshot_2014-01-21-23-32-19-1.png

Lol Ian, every word you speak is taken literally, in fact if you was to produce Wednesdays lottery numbers and say the same most would go and purchase a ticket expecting to win the jackpot.
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Posted
  • Location: Solihull, WestMidlands, 121m asl -20 :-)
  • Weather Preferences: Cold and Snow -20 would be nice :)
  • Location: Solihull, WestMidlands, 121m asl -20 :-)

All it takes is a mild airmass moving in and the cold will be gone faster than you can say Bob's your uncle, nothing inherent about cold air itself that makes it hard to shift, look at the USA when they had that bitter cold a few days ago with temps down to -40c, in places temps rose by 30-40c in little over a day. A good strong block (high heights, preferably yellows and oranges though lower ones can work but more tricky) in the right place and/or a weaker Atlantic should keep the cold in place and hopefully send some our way. Got to get there first but many hurdles to jump over yet. I'd love a good blizzard...

cold air is denser than warm air and is a lot harder too push through/against, without getting into specifics that was just the point i was trying to make to folk that don't understand that.

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Posted
  • Location: Darton, Barnsley south yorkshire, 102 M ASL
  • Location: Darton, Barnsley south yorkshire, 102 M ASL

By Monday, UKMO-GM has snow showers advecting well inland on westerly flow across e.g. W Country, M4 corridor, Wales etc. As I mentioned yesterday, the unusually chilly characteristics of the westerly flow - at least, as currently progged - looks more likely to bear wintry ppn than otherwise might be the norm for late Jan. One to watch....

by monday there might be not much left of uk! I'm increasingly concerned now. Some of you may wish to pop over to the atlantic storms thread and check it out!!!
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Posted
  • Location: East Anglia
  • Location: East Anglia

Quite so, but the drop in WBFL to 400m by early hrs Mon is striking. More striking still, as the UKMO Dep Chief includes in his briefing, is the temperature contrast he highlights across former E Germany, noting this is important "...should the winds turn easterly next week...".Posted ImageScreenshot_2014-01-21-23-40-43-1.png

Just have done with it Ian and run for president, under the moniker, Mr Popular, a vote for me is a vote for snow

This is a party election leaflet on behalf of the Blizzard party.  

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

I'm afraid the forecasts we look increasingly likely to front over next few days will be anything but popular in many districts. About to receive briefing shortly on the Sun-Mon developments and I doubt it contains anything pretty regarding Exeter's emerging views on where this all ends-up. I do re-stress it's rainfall and possibly winds that are the pressing concern, despite understandable interest on this forum for snow.

 

As I understand, even today's rain has had a considerable impact in this area (this being a locale which hasn't even been that badly affected so far). A couple of people have told me today that road conditions were treacherous as any amount of rainfall is just running of sodden fields etc straight onto public roads. I can imagine this could be a devastating period in terms of flooding for some areas.

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Posted
  • Location: Winterbourne, South Glos
  • Location: Winterbourne, South Glos

Not to be taken too literally (!!! Caution!!!) but here's modified UKMO-GM at T+144:Posted ImageScreenshot_2014-01-21-23-32-19-1.png

Hmm, Ian, reminds one of the "Bristol Channel Streamer" of 2009? I remember you getting that one nailed ahead of the pack (maybe not so far out , though :)

 

Interesting and thanks for the insight into the modified UKMO-GM output.

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Posted
  • Location: North Somerset, UK
  • Location: North Somerset, UK

Hmm, Ian, reminds one of the "Bristol Channel Streamer" of 2009? I remember you getting that one nailed ahead of the pack (maybe not so far out , though :) Interesting and thanks for the insight into the modified UKMO-GM output.

Funnily enough I immediately thought of that very same episode!!
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