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Model output discussion - late November

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12 minutes ago, Catacol said:

and then at the back end of the run we see the majority cluster reinject life into continued amplification 

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It would be true to say that this last image sees a flat pattern as the majority outcome.....but not the biggest cluster of the three. What might be going on? In the first place the vortex, as was predicted by the modelling more than a week ago, is trending towards the Siberian side following stretch via wave 2 and then sustained wave 1 warming from the Canadian side. This is clear from the 70hpa plot

 

This a good example of how people can read these differently because I wouldn't read that as the majority cluster re injecting life into continued amplification. I would read it as a typical fluid Pm/Tm phasing pattern trough/ridge/trough which of course is impossible to justify with just the one example, as is injecting life into continued amplification. Personally when taking on the difficult task of analyzing the clusters I keep the mean ext anomaly in mind because at least with that you have the NH pattern. anyway as always just 2p worth

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1 hour ago, SLEETY said:

perhaps a proper potent northerly lining up at the end of the ECM,but a poor performance from the model past 24 hours ,it’s as flat as a pancake compared to this time yesterday.Gfs has trumped it this time.

 interesting you say that how ever the question is how has the GFS trompped it when the event in question hasn’t happened yet. ☺️

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10 minutes ago, knocker said:

This a good example of how people can read these differently because I wouldn't read that as the majority cluster re injecting life into continued amplification. I would read it as a typical fluid Pm/Tm phasing pattern trough/ridge/trough which of course is impossible to justify with just the one example, as is injecting life into continued amplification. Personally when taking on the difficult task of analyzing the clusters I keep the mean ext anomaly in mind because at least with that you have the NH pattern. anyway as always just 2p worth

I would concur with that to a certain extent, the problem is with one still image at an exact time frame is that you cannot really tell whether it is a transient ridge in a mobile pattern or will actually gain latitude in the next frame, as i have said before, i would prefer the mean of all the members in that cluster over a time span of maybe a few days, then if it is a large cluster and it is showing a reasonably high latitude block, i would place more confidence in it.

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Sticking to the reliable, 2-3 days of more murk dank claggy November dismal weather - however, a change is on the way to something hopefully much drier and colder, return of frost, possible fog by the weekend to start the first month of winter. Quite an interesting evolution with a wedge of heights staying strong over Iceland, pulling down a chilly northerly, wintry showers over NE regions.

Into next week, strong agreement from the models the ridge will topple through the UK but with cold surface air, won't warm up quickly, further ahead a return to westerlies, and then possibly another cold shot from the NW, which could be potent - but this is getting too far ahead.

 

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Better ICON, Saturdays low further north again, should be some sleet/ wet snow on that northern edge of the ppn Saturday evening I would think, above 100/150m maybe but who knows, as it pulls away the cold air may undercut.👍

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Just now, Steve Murr said:

ICON still pushing the slightly more amplified runs -

AF5ADAC0-312C-4BE8-B98D-8DEB7929A471.thumb.jpeg.9c8da77dd8caf00bbaefd6d3b846ecb6.jpeg

What are your thoughts on Saturdays chances for a bit of wintryness Steve?

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Just now, snowray said:

Better ICON, Saturdays low further north again, should be some sleet/ wet snow on that northern edge of the ppn Saturday evening I would think, above 100/150m maybe but who knows, as it pulls away the cold air may undercut.👍

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Noooo, please keep that low far enough southwards that higher pressure stays in control, who wants cold rain yet again. 

It is a northerly toppler so I'm hoping high pressure can get in control and keep us cold and frosty with sunny days. 

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Just now, Steve Murr said:

Lowish risk - welsh High Ground > Brecons if the PPN makes it that far

in terms of cold we need to keep an eye on this

3DD7F141-F5E9-49C4-B74A-A08E611C4DEA.thumb.jpeg.02ec2089fa32bf963c307eb4f99376ed.jpeg

Cheers. Yes I noticed that too, fingers crossed, be nice if GFS 18z shows something like this, at D5/D6 there could still be surprises in the pipeline.

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Just now, snowray said:

Cheers. Yes I noticed that too, fingers crossed, be nice if GFS 18z shows something like this, at D5/D6 there could still be surprises in the pipeline.

What exactly is it we're looking for in terms of the arrow - sorry a little bit novice when it comes to this detail

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NOAA this evening in the same ball park as the GEFS and EPS

814day_03.thumb.gif.531fcc91e5e08ed146d6398ef83a8bcf.gif

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2 minutes ago, StretfordEnd1996 said:

What exactly is it we're looking for in terms of the arrow - sorry a little bit novice when it comes to this detail

Kink in the isobars which represents the potential for a secondary low development within the ensuing northerly flow following the clearance of the low across southern counties on Saturday. Helps pep up wintry precipitation if parameters are sufficient for such.

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1 minute ago, StretfordEnd1996 said:

What exactly is it we're looking for in terms of the arrow - sorry a little bit novice when it comes to this detail

Well thats some very cold air that could potentially be heading our way, some of the runs where showing this yesterday, it may just end up clipping our east coast but you never know. Obviously the block would have to hold with HP remaining further West/North West of the UK.

 

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1 minute ago, MP-R said:

Kink in the isobars which represents the potential for a secondary low development within the ensuing northerly flow following the clearance of the low across southern counties on Saturday. Helps pep up wintry precipitation if parameters are sufficient for such.

Thanks for this - much appreciate your response

image.thumb.png.5c74abb7ccca353cb3c848ba9a590316.png

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20 minutes ago, Steve Murr said:

ICON still pushing the slightly more amplified runs -

AF5ADAC0-312C-4BE8-B98D-8DEB7929A471.thumb.jpeg.9c8da77dd8caf00bbaefd6d3b846ecb6.jpeg

Out of interest what sort of wind speeds would that low to the NE produce as I can imagine the wind chill will feel bitter where I'm going!

Icon keeping up the interest for us🤞

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58 minutes ago, knocker said:

This a good example of how people can read these differently because I wouldn't read that as the majority cluster re injecting life into continued amplification. I would read it as a typical fluid Pm/Tm phasing pattern trough/ridge/trough which of course is impossible to justify with just the one example, as is injecting life into continued amplification. Personally when taking on the difficult task of analyzing the clusters I keep the mean ext anomaly in mind because at least with that you have the NH pattern. anyway as always just 2p worth

Yep - dont disagree with that, and I continue to think that the phase pattern is going to maintain a net westerly impact - but it is a more amplified/meridional pattern (if you take the majority cluster) than the one 4 days earlier and hence I do see a surprising tendency to extend the duration of the upcoming ridge/trough pattern rather than a move towards a flatter jet shape.

However this has to be qualified with the reality that the flat pattern clusters (2nd and 3rd placed groupings) combine to outweigh the biggest cluster....and so frankly at this range it is only an observation of interest rather than a statement of any confidence in colder solutions. A trend may develop or it may not - I’m keeping my eye on 8th December as a comparison point across each cluster run, and we’ll see where we go.

Of equal interest tonight are observations from extended EPS (300h) pointing to a return of the aleutian low in mid Dec. Good for ongoing fun with the vortex....

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1 hour ago, feb1991blizzard said:

I would concur with that to a certain extent, the problem is with one still image at an exact time frame is that you cannot really tell whether it is a transient ridge in a mobile pattern or will actually gain latitude in the next frame, as i have said before, i would prefer the mean of all the members in that cluster over a time span of maybe a few days, then if it is a large cluster and it is showing a reasonably high latitude block, i would place more confidence in it.

Just run the sequence? I tried to show that in the original post. Going by the majority cluster it represents reamplification over 72/96h.

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Just now, Catacol said:

Just run the sequence? I tried to show that in the original post. Going by the majority cluster it represents reamplification over 72/96h.

True - i think it would be a lot more helpful to be honest if they were available on meteociel in NH format.

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18 minutes ago, Kentspur said:

Out of interest what sort of wind speeds would that low to the NE produce as I can imagine the wind chill will feel bitter where I'm going!

Icon keeping up the interest for us🤞

Probably 60>70 MPH Northerlies on the western flank!

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Just now, feb1991blizzard said:

True - i think it would be a lot more helpful to be honest if they were available on meteociel in NH format.

Agreed. Ultimately I think we need to remain balanced in any case - I’ve stuck my neck out and interpreted the output as showing a slight increase in the chances for colder solutions to remain by week 2 December, but need to emphasise again that the majority of the output points to a flatter shape. It would be great for snowpers to get some joy this early in the season, but it feels too good to be true (from a cold hunting perspective obviously....). If the trend grows and solidifies then great - let’s see what develops. For now some frost in the medium term looks likely, and down in the tropical SW any time when ice forms is a moment of note!

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Not surprising to see the ec46 week 3 showing a broad scriceland low .....being a weeks mean, it likely backs up repeated pm incursions .....  how amplified would the Atlantic ridge become as it dumbbells around should this pattern verify ??

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