Jump to content
Paul

Model Output Discussion - cold spell to end Autumn

Paul

Please only post model discussion in this thread. 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

Thank you!

Message added by Paul

Recommended Posts

Year after year this Winter model watching 'gets me'  every time.During the Autumn I convince myself that this year I won't be 'sucked In'

However this last 48hrs I find myself 'buying into' some sort of Northern Blocking as we head toward Christmas when it appars at 380hrs + on the GFS

When the model shows The p.v firing up in FI my reaction is to get cross and say In my mind, FI nonsense.

  • Like 5

Share this post


Link to post
Share on other sites
43 minutes ago, Paul_1978 said:

It's so far away it's hardly worth mentioning. 

Is this not the model discussion thread? No?

Yes it’s FI, but it’s one of a number of options as we head forward to the festive week. Just because it shows what you don’t want, doesn’t mean you should tell someone it’s not worth mentioning!

  • Confused 2

Share this post


Link to post
Share on other sites
3 hours ago, bluearmy said:

Yes nick, from a personal perspective this has gone very well re the trough extension (ecm the call on this) but the warm front which came into play on Thursdays fax charts and disappeared yesterday morning is back today and it messes with the southern extent of the snowline. Euro 4 has now recognised this little low into the se of England preventing the push north of less cold uppers and mixing out of the cold with the snowline shifted south some 30 miles. however, looking at its 850/1000 thicknesses indicates that the warm front shown on the faxes is there. seems to be more emphasis on sleet/snow returning south later on tomorrow but looks messy and unsubstantial. The midlands however look like they will take a big hit tomorrow and this now extends into the n half of east anglia. (Away from the coastal strip which could be 20 miles or so)

Warm front has gone again on the latest T+24 Fax:

20171209_1012.PPVE89.thumb.png.8095b4cb4a89ad590e759bc615fce5a9.png

Would this not bring the southern extent of the snowline southwards ahead of the remaining occluded front?

 

 

  • Like 1

Share this post


Link to post
Share on other sites

The 00z ens graphs show some trend to less cold after the next 48hrs

graphe3_1000_262_93___.gifgraphe_ens3.php?mode=0&x=266&y=95&run=0&

which is not a complete surprise as the gefs/eps charts show a flattening of the Atlantic ridging in week 2 and upstream the demise of the Alaskan ridge from around day 7.

We may well squeeze another cold nw shot at the end of next week as current models are showing before that change over the west coast of NA translates to a flatter Atlantic jet by day 10.This is because the energy from the Canadian vortex is set free to move east as we lose those heights around Greenland..

EDH1-240.GIF?09-12gensnh-21-1-240.png

so something more typical at least for a while in week 2 with a more westerly type but no suggestion of anything overly mild.

Just a glance further on looking at the ext Eps and no strong signal of any influence from the Russian heights further east but upstream indications of the Pacific ridge re-amplifying which may translate to the Atlantic later but that is going into week 3 so i will leave it there. 

Edited by phil nw.
  • Like 5

Share this post


Link to post
Share on other sites
23 minutes ago, bobbydog said:

so am i feb. whatever is going on down here, the strat is taking a battering. that has to have big implications for the trop further down the line. if the stratospheric vortex is wound up tight, its difficult to see a way forward. by this point, it usually is. this year it is anything but...

going to be some fun times ahead this winter i feel....

Or in other words, the strat would be taking a battering if we got to Xmas day and the stratospheric pattern was still as shown on that chart.

Share this post


Link to post
Share on other sites

Ens say our t2m will be like the Big Dipper at Blackpool until around the 17th, at which point the key word is probably “uncertainty” but overall a warm up seems the form horse..... for now. 

753EE541-CDDA-44FB-832A-5F71DB4BFA73.thumb.gif.6472f5960f858fa8e4e45ee54fed9143.gif

 

  • Like 3

Share this post


Link to post
Share on other sites
18 minutes ago, The Enforcer said:

Warm front has gone again on the latest T+24 Fax:

20171209_1012.PPVE89.thumb.png.8095b4cb4a89ad590e759bc615fce5a9.png

Would this not bring the southern extent of the snowline southwards ahead of the remaining occluded front?

 

 

That looks like an 'old fashioned snowmaker' chart - I guess you will see how much difference it makes if the warnings are changed markedly. Last I heard they were expecting the line to be Gloucester across to Luton and then across to s norfolk

latest euro4 looks pretty much identical to 00z run though snowline perhaps 10 miles north of 00z run 

  • Like 2

Share this post


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

That looks like an 'old fashioned snowmaker' chart - I guess you will see how much difference it makes if the warnings are changed markedly. Last I heard they were expecting the line to be Gloucester across to Luton and then across to s norfolk

latest euro4 looks pretty much identical to 00z run though snowline perhaps 10 miles north of 00z run 

Several reports in SW Regional thread of various apps changing Sunday's forecast from rain to snow in the last few minutes: Gloucestershire, Wiltshire and even on the Dorset coast.

  • Like 1

Share this post


Link to post
Share on other sites

Can anyone tell me has the track of the low changed? Latest Arome run: gone is the milder air across South Wales tomorrow (initially for example Swansea was showing 10C and heavy rain) but if this is right, it would be 0-2C with snow or sleet! Look at the blues across Somerset & parts of north Devon too, again these areas looked milder on yesterday's runs as well! 

image.png

image.png

Edited by Draig Goch
  • Like 1
  • Haha 1

Share this post


Link to post
Share on other sites

Looking at the GEFS 6z mean, it's a half way house scenario compared to the operational with high pressure eventually becoming more influential across the southern half of the uk but staying more zonal further north..so, in a nutshell, according to this, the week ahead looks unsettled with cold then less cold then colder again followed by a gradual transition to more settled, especially  further south with plenty of surface cold bringing frosty nights and bright mainly dry crisp days but staying more changeable across northern uk with temps closer to average.:)

Edited by Frosty.
  • Like 1

Share this post


Link to post
Share on other sites

I certainly can't see how this chart:

20171209_1012.PPVE89.thumb.png.0392f3700d267637cc1e2026f4fcffd2.png

Could lead to this snow/rain pattern at that time:

2017121006z.thumb.png.3710a2fa79d6a9b2202ee66a0797f6f0.png

Share this post


Link to post
Share on other sites
4 minutes ago, The Enforcer said:

I certainly can't see how this chart:

20171209_1012.PPVE89.thumb.png.0392f3700d267637cc1e2026f4fcffd2.png

Could lead to this snow/rain pattern at that time:

2017121006z.thumb.png.3710a2fa79d6a9b2202ee66a0797f6f0.png

The bottom chart is out of date now, it gets nowhere near my location until around 9am (and maybe not even at all in any relevant intensity), where as that chart has it dumping me at 6am until after midday.

Share this post


Link to post
Share on other sites

Hello

So after Monday's uncertainty we seem to have a pretty good idea as to how things will develop this week. A less cold interlude from Tues-Thurs, then a cold Friday and Saturday. Where things go from here are uncertain. Here is the key point at T132:

image.thumb.png.9d34f84d8f69ed17f08d99d2af920b94.png

So the Azores high tries to move to Greenland but we have the deep low over NE Canada.... If this low moves east then the ridging of the Azores high is interrupted and the pattern is flattened. Seems to be appearing on most runs now. The Greenland high although cold based can extend the window of opportunity but it seems it won't hold on long enough (could change though). I think there are 3 plausible scenarios overall:

                   Scenario 1: 10%                                      Scenario 2: 40%                               Scenario 3: 40% - Though perhaps some cooler westerlies
image.thumb.png.a9d6a691773e11ba8ad20c7d156b410d.pngimage.thumb.png.4103338d8b480731fbd8531086ba62dd.png image.thumb.png.4177dc223e7ca6e12286ea96751ad734.png

The first a Scandi high offers a decent route back back into cold though its got to happen pretty quickly after Fridays northerly hence the lower probability.

The next two unfortunately see the PV strengthening around the S Greenland area. Scenario 2 however offers a chance to extend our cold by moving the anticyclone over the UK. That wouldn't be so bad because it would be cold and maybe the high could build and hold back the Atlantic. It could also sink but lets wait and see, that would be ~10 or more days away.  The final scenario is a return to what we have seen in recent years.  Some mild days with SW winds interspersed with colder westerlies due to the cold air outbreaks from Canada moving into the NW Atlantic.

These are just my interpretations of the model output though. Hopefully we will get a nice surprise but it wouldn't surprise me if the Atlantic woke back up again. 

  • Like 4

Share this post


Link to post
Share on other sites

Possibly same thoughts over on other side of pond, with cold over in US also taking a temporary breather for coming week or so. 

 

  • Like 1

Share this post


Link to post
Share on other sites
47 minutes ago, The Enforcer said:

Or in other words, the strat would be taking a battering if we got to Xmas day and the stratospheric pattern was still as shown on that chart.

no, the strat is taking a battering now-

npst30-2.thumb.png.76906eef7346edbbc5d4284bb0908de3.png

this chart is showing it on the ropes being pummelled, with the referee about to step in-

gfsnh-10-384-27.thumb.png.6b3561fd73e769e568fbc54e23eb7241.png

Edited by bobbydog
  • Like 3
  • Thanks 1

Share this post


Link to post
Share on other sites
20 minutes ago, Draig Goch said:

Can anyone tell me has the track of the low changed? Latest Arome run: gone is the milder air across South Wales tomorrow (initially for example Swansea was showing 10C and heavy rain) but if this is right, it would be 0-2C with snow or sleet! Look at the blues across Somerset & parts of north Devon too, again these areas looked milder on yesterday's runs as well! 

image.png

image.png

Small nudge south by the look of it but a big difference showing there, interestingly the severe gales are also showing too, could be a potent snow storm somewhere if these combine! 

image.png

image.png

image.png

image.png

image.png

image.png

  • Like 1

Share this post


Link to post
Share on other sites

FWIW, the earlier NMM in house hi-res model had more of the south midland and central southern England in play.......a case of nowcasting and lamp post watching me thinks....no more posts on tomorrow from me after my earlier moan about the amount of them! :wink:

  • Like 2
  • Haha 3

Share this post


Link to post
Share on other sites

Locking this now, new thread open:

 

  • Like 2

Share this post


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

  • Recently Browsing   0 members

    No registered users viewing this page.

×