Model Output Discussion 18th Nov.2013-12z onwards.

[Joe Levy]

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=188&y=177 (South West England)

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=258&y=2 (Northern England)

The ensembles show a huge amount of spread from the 5th with plenty of very cold options and some milder (but very few actually mild) options too.

[Methuselah]

Yes the GFS 06z has a snow event midlands northward around the 228 hours, disruption a definate if that came off

That's nine-and-a-half-days away!

 

I'm not one of those minded to 'bin the 06Z', but what little chance is there of anything like that verifying? 

[Troubleatmill]

That's nine-and-a-half-days away!

 

I'm not one of those minded to 'bin the 06Z', but what little chance is there of anything like that verifying? 

 

Haha i know, it will be gone at four oclock, but we dont stop looking at the GFS OR ECM at t144 , perhaps we should!

[bluearmy]

 

(That path with the min of -10 and day time of below -5 on the 11th is interesting!).

 thats the run which madden used to base his winter forecast !seriously, the less cold members dropping out in the medium term Edited November 29, 2013 by bluearmy

[terrier]

If only we could trust the gfs 6z. But unfortunatley i have mr murrs in my head telling me its the worst run of the day. And can be used as cannon fodder. But as all us model watches know it will be totally diffrent come 4.45pm.

[Snowman.]

If only we could trust the gfs 6z. But unfortunatley i have mr murrs in my head telling me its the worst run of the day. And can be used as cannon fodder. But as all us model watches know it will be totally diffrent come 4.45pm.

Last year the 12z was always the one to deliver this year has been much the opposite.

[Skyraker]

Ensemble watch.

 

[SomeLikeItHot]

Haha i know, it will be gone at four oclock, but we dont stop looking at the GFS OR ECM at t144 , perhaps we should!

 

But the fun bit of the models is the 144 - 216 bit, where its not so far as to be completely speculative ala GFS +384, but plenty of run to run differences to keep it entertaining and lots to discuss. 

[terrier]

Just a quick one from summer sun over on media page. Met offices response to the headlines today in a certain paper. suggest a colder spell next week should be fairly short lived ahead of a return to w/sw flow and settled weather courtsey of ian ferguson on twitter. Now that to me shows that the gfs model really doesnt have much of a clue at the moment. Think the met office must be seeing on the mogreps model that this cold spell will be a short lived affair.

[Tim Bland]

I belive the quote from Ian F is over 24rs old.... Allot can happen in 24hrs. 06Z GFS outcome is unlikely but not impossible, regardless of what any metoffice professional "forecats" after all it is a "forecast" and nothing about the weather in 7 days time is ever certain.  Lets see if there is a new trend deveolping or just a rogue run 

[bryan629]

If only we could trust the gfs 6z. But unfortunatley i have mr murrs in my head telling me its the worst run of the day. And can be used as cannon fodder. But as all us model watches know it will be totally diffrent come 4.45pm.

i wouldnt write off the 6z run because stateside this run has flipped to agree with the ecm at 114hrs according to this tweet..

 

Joe Bastardiâ€@BigJoeBastardi48m

GFS flips to ECWMF ( as usual) on east coast. Now has http://weatherbell.com storm for next week ne. Look at change pic.twitter.com/jo05aLDvyc

 

hence the big changes downstream

[radiohead]

Last year the 12z was always the one to deliver this year has been much the opposite.

 

I think we can tempted to project personalities unto these computer models, we spend so much time looking at them that might be only natural! But at the end of the end, the only difference between the 06Z and the 12Z is an update in the starting conditions for the model. It's still the same computers, running the same code, using the same forumla no matter what time of the day the run is. The only difference between them is an update in starting conditions for the model containing the latest data. Without the new starting conditions, the 12Z run would be identical to the 06Z. As Snowballz said in a great post recently, each run is as good as the other, and any differences between them are just anecdotal.

Edited November 29, 2013 by radiohead

[snowmadchrisuk]

Not a bad set of ensembles with a lot of Cold options , The 6z wasn't an outlier for 850's , infact if anything in parts of FI it was on the warmer side , but more annoying I expected the mean to be reaching -5 at 850 level in London by now and it still isn't quite there ..

 

[Summer Sun]

I belive the quote from Ian F is over 24rs old.... Allot can happen in 24hrs. 06Z GFS outcome is unlikely but not impossible, regardless of what any metoffice professional "forecats" after all it is a "forecast" and nothing about the weather in 7 days time is ever certain.  Lets see if there is a new trend deveolping or just a rogue run 

 

He tweeted it just before 8:30 this morning

 

The met office have also issued an outlook for winter http://forum.netweather.tv/topic/69782-weather-in-the-general-media-newspaper-features-etc/?p=2848537

Edited November 29, 2013 by Summer Sun

[nick sussex]

Cold snap or cold spell or damp squib? It's an interesting time to be looking at the models because those options are still on the table, theres wild swings upstream, uncertainties with low pressure and shortwave ejection in the ne USA and then a big question mark after the initial drama plays out.

 

So its really the best or worst of model soap operas depending how you look at it.

 

The intrigue for me is post any northerly because even with the ECM at 240hrs looking initially underwhelming its really not that bad, yes what looks like a mean looking PV but energy still heading south into the Atlantic, and then up pops the GFS 06hrs run with a feature to warm coldies hearts, the deep low moving east across Canada in the latter stages of the higher resolution output.

 

If we put aside the early uncertainties there is a solid trend to move the PV back to Canada, the question is will the upstream amplification remain because this is key to whether energy piles east and ends up with the high over the UK or to the south or whether an amplified wave caused by the Pacific ridge sails across the USA meeting up with the PV chunk digging energy south into the Atlantic and giving the high a kick ne'wards.

 

Theres often a misconception regarding the PV which sends most cold lovers into despair, the key for the UK is where exactly this sets up, it doesn't matter how deep or foreboding it looks, you can get cold into the UK even with the PV to the nw, the crucial part is that this doesn't set up directly to the north in southern Greenland.

 

In terms of the possible northerly  regardless of the ECM and GFS 06hrs operationals isn't a done deal, timing and shortwave uncertainty still leave a question mark over this, it is likely to turn colder but you have to have time for the deep cold to head south, theres always the problem  with these set ups that the cold flow is cut off too soon.

 

From a coldies perspective these comments from NOAA are certainly welcome,

 

FORECAST SPREAD ALOFT AND UNCERTAINTY SEEMS LESS UPSTREAM FROM THEPACIFIC AND ALASKA INTO THE WRN US...ACTUALLY EVEN AT LONGER TIMESFRAMES INTO LATE NEXT WEEK.  STRONG FLOW AMPLIFICATION ACROSS THEEAST-CENTRAL PACIFIC COMMON TO GUIDANCE LEADS TO SIGNIFICANTMID-UPPER LEVEL RIDGE BUILDING UP INTO ALASKA AND AMPLE ANDDOWNSTREAM TROUGH AMPLIFICATION AND COLDER TEMPS DOWN ACROSS THEENTIRE WRN US/ROCKIES NEXT WEEK

 

The impact of amplification there will effect the PV chunk that wants to set up in Canada in the outlook, its really how long we can sustain that amplification which will have a knock on effect on where the energy goes from the PV, sharper upstream will force some of that to head se rather than just east.

 

Theres a lot going on, could be some nice synoptics and snow but we really need low pressure and shortwaves in the ne USA to, behave themselves at the crucial timeframe.

Edited November 29, 2013 by nick sussex

[draztik]

A rather short spell of cold weather if the ext. ecm ensembles are to be believed.

day 11, sees a return to near average/slightly above temps from the west, stays this way out to day 15, with the cold weather in southern Europe at this stage.

here's day 11, 13 & 15 / temp anomaly.

Edited November 29, 2013 by draztik

[nodrog]

As regards the models this was posted not long back and seems inline with the current theme (re post if needs be).

http://www.metfy.info/news--forecasts.html look for the December forecast.

 

Great detailed Winter forecast from NW, thankyou. 

[phil nw.]

Just a general overview on the northerly and beyond.I think it's generally accepted that the initial cold shot will be something like 2-3 days duration as modeling currently shows.

After that a rebuild of the Atlantic block across the UK local seems likely.Later frames of the 00z naef's has the core of the hts anomals around W.Ireland.

http://176.31.229.228/modeles/gens/naefs/run/naefsnh-0-0-300.png?12

 

We may well retain a rather cold surface setup-dry with frosts-a lot depends on the exact placement of course but at the moment no sign of a mild Atlantic pattern setting up beyond the modeled northerly.

 

In the bad old days through the 90's- during the run of milder Winters this would have been a traditional toppler as the high sank into Europe with a raging jet coming in over the top.

 

The continual modeling of the rebuilding Atlantic ridge is in that sense doing us a favour by inducing a more north of west angle to the mean jet.

[Tamara]

Just a general overview on the northerly and beyond.I think it's generally accepted that the initial cold shot will be something like 2-3 days duration as modeling currently shows.

After that a rebuild of the Atlantic block across the UK local seems likely.Later frames of the 00z naef's has the core of the hts anomals around W.Ireland.

http://176.31.229.228/modeles/gens/naefs/run/naefsnh-0-0-300.png?12

 

We may well retain a rather cold surface setup-dry with frosts-a lot depends on the exact placement of course but at the moment no sign of a mild Atlantic pattern setting up beyond the modeled northerly.

 

In the bad old days through the 90's- during the run of milder Winters this would have been a traditional toppler as the high sank into Europe with a raging jet coming in over the top.

 

The continual modeling of the rebuilding Atlantic ridge is in that sense doing us a favour by inducing a more north of west angle to the mean jet.

Yes Phil - the Aleutian High is sufficiently poleward to keep sustaining a more amplified pattern for us downstream - and as you say that is keeping the jet stream at a more favourable angle for colder incursions. We are getting the best of an atlantic and mid latitude High pattern to keep things seasonal, despite a strong vortex approaching its traditional peak

 

In the further term we need to watch the consistent signal for the vortex to re-arrange itself back towards Canada and this will take in Greenland on its journey. At this stage we might anticipate a flatter pattern but we should retain the mid latitude High further south and average conditions

Edited November 29, 2013 by Tamara תָּמָר

[shedhead]

Bags more chopping and changing in the models across the last 24hrs, but in all fairness at the kind of range involved that's very much par for the course, especially when looking at a projected N 'erly. As others have said none of us know exactly how this will pan out, with all 3 of Nick S's cold spell, cold snap or damp squib options appearing equally possible/plausible imo at this stage.  I think few seasoned model watchers would deny the usual eastward correction of N'erly airflows once we get into what most of us would consider the reliable timeframe, but as I highlighted earlier this is by no means guaranteed to happen and even the odd westward correction cannot be ruled out entirely.

 

By all means enjoy watching the rollercoaster ride across the next 48-72hrs, but I wouldn't commit to buying a ticket until at least next Monday...just is case it leaves the rails!!  

Edited November 29, 2013 by shedhead

[bluearmy]

 

A rather short spell of cold weather if the ext. ecm ensembles are to be believed.

day 11, sees a return to near average/slightly above temps from the west, stays this way out to day 15, with the cold weather in southern Europe at this stage.

here's day 11, 13 & 15 / temp anomaly.

 

those are uppers draztik and as can be seen from the predicted london ecm ens T2 temps, at this time of year, uppers and surface dont always match. what it does show is no appetite for snowfall within the 10/14 day range.

[Ali1977]

I'm only a novice, however I just watching Gavin Ps video of the 1962/3 winter. There are similarities in the Dec weatger leading up to the cold. Azores high, temporary Northerly, then westerly flow with Azores high eventually linking a Scandy high. The latest GFS shows some if this, and in deep Fi heights do start building up towards Scandy.

No doubt I'm totally wrong but when watching the video, I thought this looks familiar.

Any more experienced people seen this?

[Iceberg]

Totally agree Nick. A pattern change is occuring across the N.hemi strong blocking seems to be certain across the northern states, with a deeply amplified, if not totally blocked jet. Models are really undecided though in how to handle any energy in NE America. and blocking in Greenland. It seems to be a classic case that the upper atmosphere doesn't support the block, but the lower down and upstream synoptics are adament. 

Models hinting therefore at transient features that are fairly wishy/washy and subject to change.

[No Balls Like Snow Balls]

I'm only a novice, however I just watching Gavin Ps video of the 1962/3 winter. There are similarities in the Dec weatger leading up to the cold. Azores high, temporary Northerly, then westerly flow with Azores high eventually linking a Scandy high. The latest GFS shows some if this, and in deep Fi heights do start building up towards Scandy.

No doubt I'm totally wrong but when watching the video, I thought this looks familiar.

Any more experienced people seen this?

 

There are simarlarites between me and George Clooney......... In that we are both male

 

Never been one for comparisons of winters gone by. Not saying your wrong though.

[Tedward1982]

Nobody knows. That is the answer. All this what if this happens, what oif that happens is really amusing. nobody can tell what is going to happen with the weather. I wish people would take heed of this. Look at the "storm" that hit us, 10 days out it was looking like 1987, then when it actually arrived it was no comparison. Lesson learned? I very much doubt it.