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Paul

Model output discussion 25th Jan onwards

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True, but worth pointing out that the pressure rise is from a ridiculously low base not much over 970Mb, so it would be astounding if the ensembles didn't call as one for a rise to some extent and at some stage.  Therefore, query whether much can be read into these ensembles.

 

however, as mpg commented, it has a consistency not seen often over the last few weeks for pressure values for that region.

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however, as mpg commented, it has a consistency not seen often over the last few weeks for pressure values for that region.

 

Fair point both of you, but with the mean peaking at 1010 Mb that's hardly High Pressure - it's moderate to moderately low.....and that's the peak!

 

Certainly gives us some hope to cling on to that the Atlantic juggernaut may slow down, if not halt altogether, I agree.

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It will be interesting to see wether or not it is on the colder side of the ensembles again and indeed if some other members follow it if the run continues to trend colder.Edit.Yet again the run trends cold toward the end.All is still to play for on the 6th February.

Yet another set of ensembles with the OP trending colder than the mean from next week

http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png

Lets hope for a continuation on the 12z run of that theme.

It may not be a very cold pattern setting in next week but it will provide cold uppers with the chance of snow for many up North, besides the Highlands.

With the usual caveats that come with these charts

http://modeles.meteociel.fr/modeles/gfs/runs/2014020606/gfs-2-120.png?6

http://www.meteociel.fr/modeles/ecmwf/runs/2014020600/ECU0-144.GIF?06-12

http://www.meteociel.fr/ukmo/runs/2014020600/UW144-7.GIF?06-06

Edited by winterof79

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Using the latest Fax output as the low nears the UK the 'gradient' that is the strength of the 2,000ft wind, or the  perpendicular distance between the isobars is shown to be around 80 knots, overland one would expect this to give 35-40 knots 'mean' speeds IF it still has that intensity as it gets overland.

 

There are all kinds of additions and subtractions that have to be made due to speed of movement of the feature, whether there is cyclonic or anticyclone curvature at any one location at any one time, all of which are built into the computer models

 

Using other empirical rules, again built into the model, would suggests gusts on the coast of 70-80 knots, and inland, as the isobars begin to open out a little, 55-65 knots decreasing to 45-55 knots with time.

 

note the speeds I quote are knots, somewhat higher in mph

Edited by johnholmes

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Using the latest Fax output as the low nears the UK the 'gradient' that is the strength of the 2,000ft wind, or the  perpendicular distance between the isobars is shown to be around 80 knots, overland one would expect this to give 35-40 knots 'mean' speeds IF it still has that intensity as it gets overland.

 

Is that the current low thats now sitting in the channel,

Thanks

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Using the latest Fax output as the low nears the UK the 'gradient' that is the strength of the 2,000ft wind, or the  perpendicular distance between the isobars is shown to be around 80 knots, overland one would expect this to give 35-40 knots 'mean' speeds IF it still has that intensity as it gets overland.

 

Is that the current low thats now sitting in the channel,

Thanks

 

 

 

no I was referring to the one in the far west of the Atlantic

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Thanks Jh, looking at a knots to MPH conversion table, pretty high wind speeds in that system.

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Yes the weather looks very nasty over the next few days, with damage likely either from wind or rain. But keeping my eye on the 11th, as its constantly being shown as cold and possibly snowy for lower ground:

Posted ImagePosted ImagePosted Image

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I must admit to being somewhat surprised with the certainty with which Tamara dismisses any amplification of the pattern out in the Atlantic even though she may well be proven correct. For my part my opinion is unchanged from that which I expressed over a week ago - that a large piece of the Canadian vortex will break off and move East and the upstream pattern behind is not nailed on flat as far as I can see. There will be a weakening of the jet and quite possibly a buckling as we head toward mid month so I do still expect to see some amplification of the pattern with a possible Atlantic ridge though as always with the caveat this may not be enough. In terms of probability I see the disruption of this current stormy pattern after mid month to be much higher than zero if not the more likely solution, perhaps around 40%. Even so that does not mean a block and cold, it just means I see things likely being quieter with an increased probability of colder interludes for now. 

 

In the meanwhile we still have Sunday's storm to contend with as well as keeping an eye on the 11th which is a very interesting day MO wise, with anything possible from a severe storm to heavy snow in the Northwest - definitely a date to keep an eye on.

Edited by Mucka

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Certainly no sign of any snowy cold of any duration in the GFS 12z Op. Yes, the small risk of transient snow on the back end of weather systems but that's it.

 

Unfortunately it's a continuance of what we are having although perhaps slighly less wet and windy.

 

In response to Mucka, i see no evidence of any amplification at H500 level and no sign of any HLB affecting our side of the hemisphere.

 

Any cold and snow is resulting from the PV finally running out of steam, but it remains at home in NE Canada.

Edited by mountain shadow

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GEM 12z at least modelling the possibility of what I am talking about though not much support for a ridge that strong at the moment.

 

Posted Image

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I must admit to being somewhat surprised with the certainty with which Tamara dismisses any amplification of the pattern out in the Atlantic even though she may well be proven correct. For my part my opinion is unchanged from that which I expressed over a week ago - that a large piece of the Canadian vortex will break off and move East and the upstream pattern behind is not nailed on flat as far as I can see. There will be a weakening of the jet and quite possibly a buckling as we head toward mid month so I do still expect to see some amplification of the pattern with a possible Atlantic ridge though as always with the caveat this may not be enough. In terms of probability I see the disruption of this current stormy pattern after mid month to be much higher than zero if not the more likely solution, perhaps around 40%. Even so that does not mean a block and cold, it just means I see things likely being quieter with an increased probability of colder interludes for now. 

 

In the meanwhile we still have Sunday's storm to contend with as well as keeping an eye on the 11th which is a very interesting day MO wise, with anything possible from a severe storm to heavy snow in the Northwest - definitely a date to keep an eye on.

 

mucka, i think that an amplification to our west is possible as the vortex spreads itself between the atlantic upper trough and developing alaskan segment. there is a window of opportunity before the next pulse of low heights is thrown out east of hudsons.  the 06z op showed how that might evolve with a weak ridge over the north atlantic and the renewed systems heading se underneath this. not the favourite at the moment but certainly not the least likely solution either.

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mucka, i think that an amplification to our west is possible as the vortex spreads itself between the atlantic upper trough and developing alaskan segment. there is a window of opportunity before the next pulse of low heights is thrown out east of hudsons.  the 06z op showed how that might evolve with a weak ridge over the north atlantic and the renewed systems heading se underneath this. not the favourite at the moment but certainly not the least likely solution either.

 

Yes I would agree with that and have posted as much for some time but of course Tamara may be right that it all simply gets "washed out" by a reorganised Canadian PV.

I was simply surprised by the weight she gave that option.

 

It has been a dreadful winter not just for the lack of cold but of course for the relentless wind and rain - even so their is plenty for the model enthusiast to get stuck into over the next week or two albeit not all fun, especially for those suffering the consequences of the charts we find so fascinating.

 

GFS ensembles 

 

NW England (snow risk up to 70% on the 11th, if only they were worth a fig!)

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=231&y=38

 

SE England

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=295&y=126

 

Central England (pressure) Good agreement out to the 11th then all hell breaks loose.

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=246&y=94&run=12&runpara=0&type=1&ext=1

Edited by Mucka

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Yes I would agree with that and have posted as much for some time but of course Tamara may be right that it all simply gets "washed out" by a reorganised Canadian PV.

I was simply surprised by the weight she gave that option.

 

It has been a dreadful winter not just for the lack of cold but of course for the relentless wind and rain - even so their is plenty for the model enthusiast to get stuck into over the next week or two albeit not all fun, especially for those suffering the consequences of the charts we find so fascinating.

 

GFS ensembles 

 

NW England (snow risk up to 70% on the 11th, if only they were worth a fig!)

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=231&y=38

 

SE England

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=295&y=126

 

Central England (pressure) Good agreement out to the 11th then all hell breaks loose.

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=246&y=94&run=12&runpara=0&type=1&ext=1

11th then all hell breaks loose?? What do you mean??

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Yes the weather looks very nasty over the next few days, with damage likely either from wind or rain. But keeping my eye on the 11th, as its constantly being shown as cold and possibly snowy for lower ground:

Posted ImagePosted ImagePosted Image

Happy birthday to me....that would make me very happy....ihope to see this come into say t72 then i will get excited.

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11th then all hell breaks loose?? What do you mean??

 

Simply that massive scatter develops at that point meaning conditions on the day could be just about anything including the kitchen sink.

Talking of ensemble pressure charts we can see that the mean pressure rises markedly from around mid month so hopefully the weather will quieten down somewhat though it may well still be rather unsettled.

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i dont agree this time with tamara i think a pattern change will show its hand with in the next few days there have been hints over all the pattern now or in the coming days is likely to endure small changes in the over all pattern indeed very stormy.

 

pv still very much in control but is very likely to reduce rapidly in strength,

there for allowing a break from the terrible weather we are having now.

 

i expect heights to build around scandi or through iceland into eastern greenland.

 

the models are toying with the idea as i expect the later run data is starting to show signs of weakening vortex,

if the pattern dont emerge with in the next few days then its possible that feb can be wrote of.

 

as for march i still feel winter will have a sting in its tail.

Edited by emotional rollercoaster

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The 11th certainly looks like the next "problem day" after the weekend storm.

 

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ECM is a horror show for the north west and Ireland. That storm doesn't seem to move with any real pace either when it hits the UK so prolonged damaging gusts and heavy rain look likely. Lets hope it gets toned down come verification.

Posted Image

Yet more secondary features following which could easily bomb too.

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The 11th certainly looks like the next "problem day" after the weekend storm.

 

Posted ImageECU1-120.GIF

I would guess 90-120mph gusts at the centre of that - hopefully it will be downgraded and moved further away from land

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the day 3 fax shows the little feature just off the sw tip of ireland that will scoot across the uk and likely bring a wintry mix with it in the following 12/18 hours.

 

the day 6 storm from yesterday now looking to have some x model agreement with GEM/UKMO/ECM in a similar place whereas GFS doesnt have the system crossing north of the pfj and it remains a weakish 'runner'. i recall nick F some time ago referencing these type of systems that come from the warmer air south of the jet and cross over to the north and the way they deepen significantly as this occurs. this does look more worrying than both yesterdays and saturdays depressions.

Edited by bluearmy

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Is that a slack Easterly flow on the ECM. Uppers playing ball on this run.

Posted Image

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