Jump to content
Sign in to follow this  
phil nw.

Model Output Discussions 12z 30/11/16

Recommended Posts

15 minutes ago, Glacier Point said:

Ian, could you qualify 'massive ramp up' as being return to climatology (as GEFS), or above tercile, and whether such similar signal exists for 70hPa or 50hPa layers ?

Return to climatology or exceeding that in some members (albeit with a minority going at times Dec-Feb the other way, into reversal). The persistence of that stronger signal (i.e. the sudden change coming after a period of exceptionally weak PV) was an underpinning consideration in how the initial 3-month outlooks were worded, when they started covering the early winter period and talked of a higher risk of colder/blocked set-ups for *early* winter but - as Adam Scaife blogged - a shift away from that sort of story could then dominate further into the season (latest outlook focuses this more towards Feb). I'm not sure re signals other than at 10hPa.

Edited by fergieweather

Share this post


Link to post
Share on other sites
1 hour ago, Summer Sun said:

1ac6d7ec-c4a1-4dd6-819e-133ccb4f3d17.png

Yes - but last year wind speeds were considerably higher. Still comparatively a pussycat.... and the impact of the warming we have had is downwelling now. Further warmings may also occur if forecasts pan out. Nothing to fear here. I'm surprised Matt sees a recovery like this as worth posting tbh

Share this post


Link to post
Share on other sites
1 minute ago, fergieweather said:

Return to climatology or exceeding that in some members. The persistence of that signal (i.e. the sudden change coming after a period of exceptionally weak PV) was an underpinning consideration in how the initial 3-month outlooks were worded, when they started covering the early winter period and talked of a higher risk of colder/blocked set-ups for *early* winter but - as Adam Scaife blogged - a shift away from that sort of story could then dominate further into the season (latest outlook focuses this more towards Feb). I'm not sure re signals other than at 10hPa.

Thanks

Share this post


Link to post
Share on other sites

Sorry off topic mods but wholly appropriate for the mass hysteria that's broken out.

IMG_0087.PNG

Share this post


Link to post
Share on other sites

There's so many questions that could be asked about this chart. A ridge of high pressure tries to build in from the W but whether this manages to successfully build in and settle things in down for Christmas can only be answered over the coming days. I'm somewhat doubtful that it will calm down in time for the festive period, it looks fairly active over Greenland, not where the coldies want it to be.

ECM1-240.GIF?02-12

Edited by Grimers

Share this post


Link to post
Share on other sites

GFS 12z at t114 has everything a shifted fair bit more 'top right' compared to the 6z, which makes a huge difference to the centre of the low over the US

6z gfsnh-0-120.png?6  12z gfsnh-0-114.png?12

Share this post


Link to post
Share on other sites

@Mucka, that's all well and good. But, I wouldn't want to set my expectations too high anyway in case of dissapointment. I would hope that I don't class myself as a glass half empty person, but if we became too hopeful then surely this thread would turn into a melt down situation when what we've set our hopes up for doesn't come to frutition. It's probably best that we try not to predict what could and might happen ahead of what the models show, it's already hard enough as it is trying to work out what could happen in the forecast period at the present time.

Edited by Grimers

Share this post


Link to post
Share on other sites
31 minutes ago, Ravelin said:

GFS 12z at t114 has everything a shifted fair bit more 'top right' compared to the 6z, which makes a huge difference to the centre of the low over the US

6z gfsnh-0-120.png?6  12z gfsnh-0-114.png?12

 
 
 
 
 
 
 
 
 

Indeed our eyes need to be drawn to developments of the Eastern Seaboard post D5 onwards, as alluded to in my post from this morning. We certainly need to look at how the NH Jet is handled by cross-model outputs from D5 to D7 in particular when prejudging FI outputs.

I don't think the mid-term is nailed yet alone Mid-December and beyond, although we are receiving some sound guidance from a few respectable netweather members, who clearly know the time of day. :hi:

And as if by magic, the HP influence is shown to be stronger than previously modelled by D6 (8th December) according to UKMO 12z. A case of what's changing IMBY, very little, that's what, lol. Will the ECM 12z follow where the UKMO left off? Perhaps it's time to adjust my percentages in this morning's post to something more akin to a 50:50 chance of an Atlantic influence taking over from a 70-80:20-30 percentage chance by this time next week.

Edited by gottolovethisweather

Share this post


Link to post
Share on other sites
7 minutes ago, Ravelin said:

GFS 12z at t114 has everything a shifted fair bit more 'top right' compared to the 6z, which makes a huge difference to the centre of the low over the US

6z gfsnh-0-120.png?6  12z gfsnh-0-114.png?12

Just a thought on this. It's a long shot, but if the high is a little further west, eastern areas may avoid a flow with a sea-track at T144. Would make it much cooler than currently forecast, at least for a day or two.

Share this post


Link to post
Share on other sites
1 hour ago, Barry95 said:

This winter WILL most likely be better than last winter

Well it's already started colder and frostier so early signs are good!:santa-emoji:

ukmintemp.png

ukmintemp (1).png

ukmintemp (2).png

Share this post


Link to post
Share on other sites

Although the Gfs 12z becomes mild from next midweek, it doesn't look super mild with temps in the mid to high teens celsius like we saw last December, temps look nearer to 11-13c range with some sunshine but also bands of rain, especially affecting the north & west.

ukmaxtemp.png

ukmaxtemp (1).png

ukmaxtemp (2).png

ukprec.png

hgt500-1000.png

ukmaxtemp (3).png

Edited by Frosty.

Share this post


Link to post
Share on other sites
Just now, Frosty. said:

Although the Gfs 12z becomes mild from next midweek, it doesn't look super mild with temps in the mid to high teens celsius like we saw last December, temps look nearer to 11-13c range with some sunshine but also bands of rain, especially affecting the north.

Still, you've got to admit the temperatures shown by the GFS aren't far off this time last year and we don't want anything like we had last year. Anyway, back to the here and now...

Share this post


Link to post
Share on other sites

Quite big differences even at t144 between the GFS & UKMO, especially over the USA...

UKMO UN144-21.GIF?02-17  GFS gfsnh-0-144.png?12

It'll be interesting to see where the ECM sits on this later.

Edited by Ravelin

Share this post


Link to post
Share on other sites

Its one of those outputs where you look for small chinks of hope that the mild pattern could break down quicker than first thought and there is some to a very small extent on the GFS 12Z run. I think the 144-168 hour mark needs watching closely as we could see some sort of development to slow/stop the jet stream from heading into us although at this stage the models are suggesting the jet will power through eventually.

There will be some Atlantic influence next week with the rain especially in the west but by and large its the Euro high that is affecting our weather hence why the UK stays in the tropical airmass for quite a few days.

I'm not the biggest fan of large range forecasts but I do appreciate the science and the thinking that goes behind in making them but I do think putting dates on potential interest is always a big risk though because when they don't come off, questions will be asked and frustration grows. I think the frustration is growing because going back in Mid November there was a lot of hype for the end of Nov to the start of December for blocking and that has not really happened and now the goalposts are being moved to mid Dec but then you get hints when things may not go to plan it gets pushed back further again but I think its just a case of waiting and seeing if anything comes off. Far too early to say if Mid December will be cold/mild/average because the weather outlook can switch quite rapidly.

Share this post


Link to post
Share on other sites
26 minutes ago, Grimers said:

@Mucka, that's all well and good. But, I wouldn't want to set my expectations too high anyway in case of dissapointment. I would hope that I don't class myself as a glass half empty person, but if we became too hopeful then surely this thread would turn into a melt down situation when what we've set our hopes up for doesn't come to frutition. It's probably best that we try not to predict what could and might happen ahead of what the models show, it's already hard enough as it is trying to work out what could happen in the forecast period at the present time.

I guess it is up to each individual, everyone handles disappointment differently. It is just a matter of balance, I'm not trying to call out anyone, I understand the disappointment but personally prefer to try and remain upbeat, especially when blocking is still favoured.

As far as interpreting the output goes, I think most of us want cold snowy weather so we naturally look for ways we might get there and more times than not are disappointed because our winter climate is more naturally mild and wet but surely we can handle it? It would be a very boring forum if we all simply posted the Op charts and described what they show instead of where they might go or how they might change?

After all the output is a continuous state of flux and describing a day 8 op chart would likely be describing something that is just as unlikely to happen as any analysis of how things might change.

For me personally that is where all the real fun is, second guessing the output and outlining areas of uncertainty and I think that is viable so long as we are basing that on current output be it ensembles or simply a possibly different evolution to what the models currently predict. 

I would expect to be wrong more often than right where forecasting changes not yet modeled but then I'm not saying these things will happen - I'm not making forecasts, I am outling areas of uncertainty and outlining possibilities whether they come to fruition or not with the usual caveats. It is very much take it or leave it fodder bu there you go. :santa-emoji:

Edited by Mucka

Share this post


Link to post
Share on other sites
2 minutes ago, Grimers said:

Still, you've got to admit the temperatures shown by the GFS aren't far off this time last year and we don't want anything like we had last year. Anyway, back to the here and now...

True nevertheless, but given the setup last year we were far more prone to mild wet weather than this year. Given the unpredictability of this year and the backing of something colder in general we "hope" to see this brief mild spell not so dominant as last year.

Share this post


Link to post
Share on other sites

Well said. I have to admit, I did post a while back explaining what could happen around the festive period. So, you're right, using the evidence we already have and then trying to guess what could happen is where all the interest lies.

Edited by Grimers

Share this post


Link to post
Share on other sites
4 minutes ago, Frosty. said:

Although the Gfs 12z becomes mild from next midweek, it doesn't look super mild with temps in the mid to high teens celsius like we saw last December, temps look nearer to 11-13c range with some sunshine but also bands of rain, especially affecting the north & west.

ukmaxtemp.png

ukmaxtemp (1).png

ukmaxtemp (2).png

ukprec.png

hgt500-1000.png

ukmaxtemp (3).png

I'm not sure how much sunshine there will be to be honest, looks like it could be a fairly cloudy week coming up, especially once the SW'ly sets in as tropical maritime air tends to have a lot of cloud associated with it. Rainfall amounts will be most great on Western hills although with the dry period we are having and the fact the models are not hinting at any fronts stalling then whilst some areas could recieve quite a bit of rainfall(because the air is so moist) I think flooding is unlikely so no real signs of any repeats of last December.

Share this post


Link to post
Share on other sites
5 minutes ago, Ben Sainsbury said:

True nevertheless, but given the setup last year we were far more prone to mild wet weather than this year. Given the unpredictability of this year and the backing of something colder in general we "hope" to see this brief mild spell not so dominant as last year.

Gfs 12z is utterly hideous for coldies, raging jet, tick, strong westerlies,tick, very mild, tick,strong euro slug high,tick, zero blocking to the north, tick.And to cap it all, potential for flooding...

Edited by northwestsnow

Share this post


Link to post
Share on other sites

Yep, GFS is carnage from start to finish.

But I think it is wrong

Even when split the PV (which is does), it seems to rotate them around themselves as if it were one entity, thuse keeping the zonal flow going.

Edited by warrenb

Share this post


Link to post
Share on other sites
9 minutes ago, Geordiesnow said:

I'm not sure how much sunshine there will be to be honest, looks like it could be a fairly cloudy week.

I'm not sure either but this weekend will see increasing amounts of sunshine, especially by sunday as drier continental air arrives and early next week should be bright / sunny, especially further south and east apart from where fog lingers. When the swly Tm air mass arrives, I expect there will still be some sunshine, mainly to the lee of high ground but there will be some rain around too, probably dullest across the western side of the uk from midweek.

Edited by Frosty.

Share this post


Link to post
Share on other sites
7 minutes ago, northwestsnow said:

potential for flooding...

Hmm, I think flooding is pushing it, yes there may be for parts of NW England and Scotland, but due to low ground water levels, there won't be on a national scale like we saw last Winter.

108-779UK.GIF?02-12 132-779UK.GIF?02-12

Edited by Grimers

Share this post


Link to post
Share on other sites

Interestingly, right at thend end it produces a flow which would match the ECM anomaly posted this morning. Jet is south, with weak high pressure to the north.

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  

×
×
  • Create New...