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Model output discussion - winter proper underway

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

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44 minutes ago, CanadaAl said:

Yeah GP, Tamara and others touched on this when they mentioned about moving into a new MJO phase. The models will continue to make a dogs dinner of it until at least mid next week. 

You hope of course that is the case or reason.  They made a dogs dinner last couple of weeks really so all to play for.  Incredible cold night time temps next few days.....-15c in the offing somewhere and sub -10c possible in England and Welsh Marches.... proper cold

 

BFTP

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26 minutes ago, Nick F said:

Entered phase 7 yesterday according to the RMM plots, whether it motors through to P8 and 1 remains to be seen, though perhaps at low amplitude according to some plots:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

Phases 7/8/1 correlate to producing colder patterns, but there is obviously a lag of 10+ days from these phases, so may not be until later in December we may see changes, maybe in time for Xmas?

With a little poetic license one could easily argue that phase 7 is very similar to what the anomalies are indicating

DecemberPhase7all500mb.thumb.gif.663124610a0cd5e81b907516b85eaa98.gif

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28 minutes ago, Frosty. said:

I don't think he's a pessimist at all, more like a realist as it does look like we are on course for a phase of positive NAO with the northern arm of the jet cranking up in the run up to christmas (week 2)...the week ahead looks generally chilly though.

The GEFS 12z mean mid range is a good example of the point I was making, it looks like typical atlantic driven weather beyond the next week or so with the pattern becoming flatter (zonal) milder with high pressure to the sw / s and lows to the nw...some fine spells further s / se closer to high pressure but becoming more generally unsettled as time goes on..positive NAO.:)

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Edited by Frosty.
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8 minutes ago, Frosty. said:

I don't think he's a pessimist at all, more like a realist as it does look like we are on course for a phase of positive NAO with the northern arm of the jet cranking up in the run up to christmas (week 2)...the week ahead looks generally chilly though.

Yes Frosty, some low minimums progged on the models for the next few days followed by a less cold westerly then another NWly/Nrly plunge next weekend. After that it could turn milder but who knows for how long? Given that at the moment the background signals are quite favourable then I don't see any reason for despondency. 

It would be great if we see a return to cold conditions before Christmas but it's far too early to make any judgement on that. Even the day 10 chart on the ECM only takes us to the 20th. Hopefully we will see a move towards something colder showing up in the later stages of the runs as the week progresses  - something which would perhaps tie in with the thoughts of some of the longer range experts?

Here's hoping at least. Although it's already been better than the whole of last winter anyway. :smile:

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I don't disagree @frosty - we've been talking about this for a few days now. Beyond that..... all to play for!

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Well a couple more cold days to come with hard frosts over the snowfields-it's been a while since we could say that!

So we now look ahead and the rest of the week looking less cold but still fairly chilly until the end of the week but Atlantic fronts from mid-week finally modifying our pool of Arctic air.

The 12z runs still showing the demise of the upstream Alaskan ridge for a few days from around day 6.This frees up the Canadian trough to drive east flattening the Atlantic ridging,at least temporarily in week 2.The ens charts do show that after the north westerly next weekend we should expect a less cold westerly pattern for a few days

graphe3_1000_263_93___.gifgraphe_ens3.php?mode=0&x=263&y=93&run=12

 

Day 9 means

gensnh-21-1-216.pngEDH1-216.GIF?10-0

The later eps/gefs do indicate the return of the Alaskan ridge quite quickly though so along with the ongoing cross polar +ve height anomalies we are certainly not looking at our usual mid December strong zonal pattern around the globe.

Time will tell whether that resurgent ridging upstream will translate into the Atlantic. 

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3 minutes ago, phil nw. said:

Well a couple more cold days to come with hard frosts over the snowfields-it's been a while since we could say that!

So we now look ahead and the rest of the week looking less cold but still fairly chilly until the end of the week but Atlantic fronts from mid-week finally modifying our pool of Arctic air.

The 12z runs still showing the demise of the upstream Alaskan ridge for a few days from around day 6.This frees up the Canadian trough to drive east flattening the Atlantic ridging,at least temporarily in week 2.The ens charts do show that after the north westerly next weekend we should expect a less cold westerly pattern for a few days

graphe3_1000_263_93___.gifgraphe_ens3.php?mode=0&x=263&y=93&run=12

 

Day 9 means

gensnh-21-1-216.pngEDH1-216.GIF?10-0

The later eps/gefs do indicate the return of the Alaskan ridge quite quickly though so along with the ongoing cross polar +ve height anomalies we are certainly not looking at our usual mid December strong zonal pattern around the globe.

Time will tell whether that resurgent ridging upstream will translate into the Atlantic. 

Also noticed the dip in temps right at the end of gfs and ecm ens -25th Dec :)

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Quite a few times it's been hinted by the models that the block over Eastern Europe may well show some resistance with most of the Atlantic energy going up and over the top of scandi. This would prep the Russian high further. I wouldn't be surprised if we start seeing easterlies being modelled within the next 2 weeks. 

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NOAA seem to think the troughing in the east USA could well return the week after next and dependent on the amplitude of that this could downstream deliver some interest to the UK.

The possible renewed upstream amplification could well be in relation to the lagged MJO effect, have the models got the correct timing of that if does verify?

In terms of tonights ECM op it is at times both a pressure outlier aswell as the warmest solution for London and I wouldn't discount the GFS 12hrs trend just yet.

 

 

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12 minutes ago, nick sussex said:

NOAA seem to think the troughing in the east USA could well return the week after next and dependent on the amplitude of that this could downstream deliver some interest to the UK.

The possible renewed upstream amplification could well be in relation to the lagged MJO effect, have the models got the correct timing of that if does verify?

In terms of tonights ECM op it is at times both a pressure outlier aswell as the warmest solution for London and I wouldn't discount the GFS 12hrs trend just yet.

 

 

- mmm I think the models as I said earlier are going to struggle in the coming days - underplaying the generally amplified flow, ECM is hinting at renewed amplification 19-20 Dec, and there is a signal for a deep long wave trough once again to anchor down through NE USA/E USA.

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pub run interesting at 132, better heights to the north, vortex further west and trough disruption  to south of Iceland. interesting trend, maybe we get another slider on subsequent run tomorrow.

gfsnh-0-132.png?18

 

Edited by pages
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Just a glance at NOAA this evening. Not to say much else as nothing has changed from this morning but the 8 14 does illustrate the strong upper flow from the eastern seaboard that becomes more diffuse in the east for reasons already given. Neither the GEFS or EPS mean anomalies this evening contradict this suggested pattern in any significant way

610day_03.thumb.gif.9cb9aea0578e5fe3f3186bbeb19b7245.gif814day_03.thumb.gif.317a4dd079d0f1faedfbc0798a8aab4c.gif

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1 hour ago, Paul_1978 said:

But we've known this for quite a few days now Frosty. Everyone knows we're going to have a milder or "less cold" spell. 

The post suggested a worry about longer term outputs and I don't know why when many of our learned posters have suggesting a return to colder weather late in Dec/early Jan. Again we've known this for some days now. 

Now is the time to relax and wait and not unduly worry about the short/medium term output in my view. We are only 10 days into winter after all. 

2

For anybody wondering, we humans and current computer modelling techniques do NOT allow us to know anything for certain, as denoted by what has just happened over the past 24 hours with the snowfall. Not an attack on you, per se but your highlighted sentence above should perhaps replace the word "knows" so that it states "supposes" or "forecasted" i.e. guesswork. Yes, it is the best advice we have on offer currently and all of us will interpret things differently as do all the various weather models and their individual members runs. I would suggest others follow who or what model they want to but never take anything for granted. My prediction is the milder zonal blip will be brief in duration and to be fair, we can't even predict what will happen tomorrow yet with any great certainty either. The bigger stratospheric effects are often lost on me so I'll take on board others views there but I will never take any forecasts post D4 with high confidence levels, more especially so at this time of year.

 

Night all, enjoy the snow where you have it and do take care out there during that morning commute. :hi:

Edited by gottolovethisweather
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14 hours ago, nick sussex said:

 

 

Looking within closer range, Thursday is looking quite interesting, signs of some form of secondary low development splitting from the main low due to move through north Scotland, this could have the effect of building in a stronger ridging of the azores northwards and hold back the trough trying to dig across from eastern seaboard, another NW-SE slider may form again.. 

Thursday could deliver some low level snow to anywhere ahead of the low/trough development.

 

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14 minutes ago, knocker said:

Just a glance at NOAA this evening. Not to say much else as nothing has changed from this morning but the 8 14 does illustrate the strong upper flow from the eastern seaboard that becomes more diffuse in the east for reasons already given. Neither the GEFS or EPS mean anomalies this evening contradict this suggested pattern in any significant way

610day_03.thumb.gif.9cb9aea0578e5fe3f3186bbeb19b7245.gif814day_03.thumb.gif.317a4dd079d0f1faedfbc0798a8aab4c.gif

Yes, a confluent trough in the west and slightly diffluent exit for the 500 mb flow over the UK. This may mean not only a westerly flow over the Atlantic but with large temperature contrasts, surface features will form just east of N America and deepen in the diffluent area around the UK. So maybe a rather stormy period?

Edited by johnholmes
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36 minutes ago, pages said:

pub run interesting at 132, better heights to the north, vortex further west and trough disruption  to south of Iceland. interesting trend, maybe we get another slider on subsequent run tomorrow.

gfsnh-0-132.png?18

 

Please please not another slider.

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22 minutes ago, johnholmes said:

Yes, a confluent trough in the west and slightly diffluent exit for the 500 mb flow over the UK. This may mean not only a westerly flow over the Atlantic but with large temperature contrasts, surface features will form just east of N America and deepen in the diffluent area around the UK. So maybe a rather stormy period?

At least that would raise hopes of some colder polar maritime shots with wintry ppn and frosty nights mixed in with the milder, wet and very windy spells..could be worse, hopefully one of the colder shots will coincide with christmas!:santa-emoji: 

Edited by Frosty.
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1 minute ago, booferking said:

Vortex sheared in half again late in FI.:shok:

Screenshot_20171210-225525.png

looks very nice - pity the one half is shoved over us. 

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2 minutes ago, booferking said:

Vortex sheared in half again late in FI.:shok:

Screenshot_20171210-225525.png

And a huge chunk of it stuck over Greenland.

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So after a mad day off radar watching. It's looking like a trend to see a mild spell from GFS and ECM after the next weekend if they are correct. But has other have posted wouldn't take anything for granted with the models has they could all change overnight. I really love the thread as it gives me a chance to talk about what I love and enjoy without getting told to shut up by our lass ha ha. Back to the weather anyway. I think 2017/18 could be a great winter and will be more ups and downs and would not want to spend it anywhere else than in here. Cheers.

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Even if we do have a milder, more cyclonic spell in the latter part of December, that wouldn't necessarily be bad. A lot of famously (or infamously) cold winters have had milder, even stormy periods at some point during December. I'm staying hopeful and so should you lot! :)

Edited by LetItSnow!
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