Model Output Discussions 12z 30/11/16

[bluearmy]

5 minutes ago, IDO said:

I thought you would look deeper, just I am a bit wary without viewing myself. Thanks.

The 06z is a law to itself and I would never take it seriously (after D7), especially at a weekend.

Also, I'm not convinced which segment will end up the master in two weeks. It did look as though would be the Canadian a day or so ago but the Siberian may be fighting back ! 

[Singularity]

It is worth watching out for signs that the vortex might elongate enough to place the Canadian lobe more toward central Canada rather than east. Then you have ridge building potential in our vicinity.

Add in a bit of MJO action in phase 3 as the ECM ens. and too a lesser extent GEFS are exploring with a few perturbations, and the ridge gains further support and could become a strong mid-lat block over us or just to the E/NE.

Utilise upstream amplification and the ridge on the Pacific side to actually split the tropospheric vortex and you have a route to HLB by around mid-month.

 

Those are the positive options as I see them, in order of increasing difficulty to achieve.

Maybe GEFS is just starting to shake off the excessive gain of westerly momentum in the N Atlantic, which I believe may have been associated with thinking the MJO would hang back in phase 2.

If not, we could see the vortex remain elongated, regroup on the Canadian side (worst case scenario unless perhaps it's far enough west), or a mixed state followed by a regroup on the Siberian side, which is possible given new lower to mid-strat. warming edging into N America from the Pacific, but this isn't until 10-16 days from now. These are less preferable to building higher heights in our vicinity, IMO.

Edited December 3, 2016 by Singularity

[bobbydog]

20 minutes ago, ITSY said:

Equally, a lot remain fairly mobile so let's not count chickens yet. The last few days may well yet prove that we do that to our own peril, and at severe costs to our mental health...

However, even the mobile options are not 'mild' and nearly all of them show amplification in some form.

[ITSY]

8 minutes ago, bobbydog said:

However, even the mobile options are not 'mild' and nearly all of them show amplification in some form.

"expect the worst... and you won't be disappointed....." 

[legritter]

Afternoon all posters ,there seems to be some Buzz on this forum today ,good end run from ECM today lets hope it continues tonight .looking good on the ens also ,wonder what update Met office will do today but i dont expect much change to their wording as caution is the word ,[far to many media outlets ready to pounce] .

So as we stand more frosts for some over coming days then milder air and atlantic fronts becoming more active .Looking at northern profile later next week and we have some quite cold air to our far north and far n west , gfs bringing in ever increasing deeper lows towards us ,and IF ECM chart 9/10 is on the ball these lows [Could ]turn further south , perhaps we will see some very cold 850 s moving south with time .Perhaps just a thought but perhaps Barbara [named storm ] will make it on Stage in about 8 days time , all interesting and of course not what some of us would like to see but now its december any snow chances will be greater than those back in november . So today is an upgrade for coldies and snowys , tonight i,m sure many of us will pull the sofas out and watch the show from there .for me looking at the northern profile over the pole [as presently forecast ]it looks like there are areas where high pressure could form in norther latitudes ,lets hope we arein the firing line ,Our friends across the pond are getting excited as their weather takes on a wintry look at last ,catch you all up later i,m off to dig the garden now its thawed a bit ,and of course before the next freeze !

 

[nick sussex]

Afternoon all

Well my mood has slightly improved today! We're still though trying to find a route to cold and the fog still hasn't cleared.

The ECM surprisingly manages two consecutive runs with a similar trend, the UKMO at T168hrs does support its pattern from what we can see on the Atlantic only output.

We are seeing differences upstream between the GFS versus the Euros, this comes down to the handling of that deep low near the ne USA at T168hrs. The GFS is more progressive and flatter and has no ridge ahead of it, instead it phases that low with one to the west of the UK. At that point unless you had good trough disruption and a strong block to the north to divert the jet much further south you're chances of cold are very low.

Of interest with the ECM is that high pressure cell near Iceland, the movement of the PV looks to be nw and so any realistic route to cold needs to come from a high toppling towards Scandi. As yet the ECM ensembles aren't really interested in this, a few look to go that way but theres not a strong signal for this.

There are lots of uncertainties later next week for the USA which will effect the pattern for us. This is in relation to whether the southern and northern streams of the jet interact and phase over the central USA. We want the phasing solution as this will lead to a slower ejection of low pressure from the ne USA.

This uncertainty is whats causing the difference between the GFS and ECM especially. So for the timebeing until that's resolved its difficult to have too much confidence in any of the outputs.

Below you can see the GFS 06hrs run to T138hrs and the ECM 00hrs to T144hrs. You can see the huge difference we're seeing due to phasing issues, timing of phasing and where that takes place.

GFS                                                             ECM

 

 

Edited December 3, 2016 by nick sussex

[Gael_Force]

1 hour ago, Ali1977 said:

Some very very good ENS this morning, 6 or 7 very cold and possibly the best so far this season - are we back in the game coldies.

That's about the best shift I've seen this season in the 4 run comparison.

 

[IDO]

11 minutes ago, Gael_Force said:

That's about the best shift I've seen this season in the 4 run comparison.

 

If you look at the 06z run (which you shouldn't really) with the seasonal average in you get this:

  2m temps: 

The mean T850s above the seasonal average for 14 days and it only dips on D15 & 16, which at that range is probably of little worth. The reason the drop looks so big is that in the next week we are getting roaring warm uppers,so  less to do with a cold period coming and more from the extraordinary warmth incoming. So a slow return to average in week 2 but probably not as cold as November average anomaly even then, looking at the mean 2m temps^^^.

Of course week 2 has lots of uncertainty but a drop in temps compared to next week is a relative certainty bearing in mind next week's uppers.

[nick sussex]

A word about the GEFS. NCEP have commented that both the GFS op and GEFS are much quicker than the ECM with the progression of that deep low. That in effect means that the GEFS are overall flatter that their later solutions might also be skewed. It depends on which model has the correct solution but the evolution downstream is very much effected by those earlier differences between the models. Hopefully we can get this resolved this evening.

[ITSY]

3 minutes ago, nick sussex said:

A word about the GEFS. NCEP have commented that both the GFS op and GEFS are much quicker than the ECM with the progression of that deep low. That in effect means that the GEFS are overall flatter that their later solutions might also be skewed. It depends on which model has the correct solution but the evolution downstream is very much effected by those earlier differences between the models. Hopefully we can get this resolved this evening.

So presumably this would suggest that the amplification and WAA we saw on the 06z ensembles was being undercooked? 

[Frosty.]

A front loaded winter appears to have gone out of the window with an increasingly mild and unsettled spell developing next week although the southeast may escape with only small amounts of rain. The generally mild unsettled spell extends to at least mid month before a split appears with some support for continuing average / mild zonality and the other option for benign high pressure to build in again but no sign of any snow being hinted at whatsoever.

Edited December 3, 2016 by Frosty.

[nick sussex]

1 minute ago, ITSY said:

So presumably this would suggest that the amplification and WAA we saw on the 06z ensembles was being undercooked?

Well that's if the ECM is correct. We don't know yet, the GFS and GEFS do normally have a progressive bias and that's been noted by NCEP. We'll just see what happens tonight.

[karlos1983]

20 minutes ago, Frosty. said:

A front loaded winter appears to have gone out of the window with an increasingly mild and unsettled spell developing next week although the southeast may escape with only small amounts of rain. The generally mild unsettled spell extends to at least mid month before a split appears with some support for continuing average / mild zonality and the other option for benign high pressure to build in again but no sign of any snow being hinted at whatsoever.

Frosty, I think that's a tad hasty! I mean the first half of winter is until mid January. We don't know with any confidence what will unfold come mid month. I'm a bit surprised by that comment 

[Ali1977]

22 minutes ago, Frosty. said:

A front loaded winter appears to have gone out of the window with an increasingly mild and unsettled spell developing next week although the southeast may escape with only small amounts of rain. The generally mild unsettled spell extends to at least mid month before a split appears with some support for continuing average / mild zonality and the other option for benign high pressure to build in again but no sign of any snow being hinted at whatsoever.

You mean the 2nd week of Dec? Not the first half of winter? 

[karlos1983]

33 minutes ago, nick sussex said:

A word about the GEFS. NCEP have commented that both the GFS op and GEFS are much quicker than the ECM with the progression of that deep low. That in effect means that the GEFS are overall flatter that their later solutions might also be skewed. It depends on which model has the correct solution but the evolution downstream is very much effected by those earlier differences between the models. Hopefully we can get this resolved this evening.

Highlighted quite nicely here I think Nick

 

[Jeremy Shockey]

In light of Nick's comments, i wonder whether the GFS has indeed done its usual trick of " grabbing hold " and going with a theme of zonality for far too long due to its progressive bias ( especially if some of its starting values are wrong ! ) .This would tie in with Ian's comments earlier in which he pointed out the volatile response of some operational models based on relative dominance of initial starting positions.

 

[stewfox]

1 hour ago, Frosty. said:

A front loaded winter appears to have gone out of the window with an increasingly mild and unsettled spell developing next week although the southeast may escape with only small amounts of rain. The generally mild unsettled spell extends to at least mid month before a split appears with some support for continuing average / mild zonality and the other option for benign high pressure to build in again but no sign of any snow being hinted at whatsoever.

Might do another 24hr review, after the ECM and GFS GEFS  update , with the GFS having the biggest flip flops on. 

All we know its like south westerlies are likely to return next week for a short time and that's been well forecast but post that ? Experts are now saying mid range the signals are very mixed. 

15-31 dec could be deep freeze and that's still front loaded for me.

We need cold air coming in from all sides.

GFS might  Flip flop ??? More runs needed , loads more runs

 

 

Edited December 3, 2016 by stewfox

[ArHu3]

16 minutes ago, Jeremy Shockey said:

In light of Nick's comments, i wonder whether the GFS has indeed done its usual trick of " grabbing hold " and going with a theme of zonality for far too long due to its progressive bias ( especially if some of its starting values are wrong ! ) .This would tie in with Ian's comments earlier in which he pointed out the volatile response of some operational models based on relative dominance of initial starting positions.

 

I noticed that GFS picks up a pattern far into FI, holds on to it for a few days and then loses it, then suddenly EC picks up the same pattern and GFS follows a day later but since GFS FI fluctuates so much from run to run that could just be coincidence

[Man With Beard]

4 hours ago, johnholmes said:

For what they are worth here are links to the last outputs of the 500mb anomaly charts

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

The ECMWF-GFS outputs issued this morning with both showing a flow from the Atlantic but with differences in heights shown over Greenland

NOAA from last night, 6-10 and 8-14; as has been the case pretty constantly the 8-14 shows a flow with the Atlantic as the main feature. The 6-10 is faily similar near the UK but keeps the high level +ve values NW of Alaska, a feature it has shown for a number of days.

There seems not much, other than these +ve heights at high latitude, to suggest any major cold outbreak. The 14 day outlook takes us to 17 December.

It is unusual for the NOAA outputs especially to be far out if they are showing consistency over several days, (this they have done). So a waiting game for those wanting deep cold with snow.

Remember they are mean charts so individual days may not show quite the same pattern. But it would be a quite unusual event if they are proven totally wrong over the periods they are valid for.

I have to add something I go on about throughout the year. There is little to be gained comparing one run to the next at extended periods. Compare like times and also check with their ensembles for a less volatile view of how the models are predicting the weather.

 

 

John, thanks as ever, I imagine you are close to the mark but I did think last night - a lot of output sees big differences between D8 and D14 conditions. I guess the mean D8-D14 would not yet represent, say, the D12 to D14 situation well in this scenario, as it will be masked by the presence of the Euro high at D8/D9 (as you kind of allude to)??

Edited December 3, 2016 by Man With Beard

[Scandinavian High.]

Haven't see nothing cold like this for London in a while maybe a trend I be keeping an eye on this . Maybe high pressure to the north east cold  air moving in from the east well see anyway time will tell 

Edited December 3, 2016 by abbie123

[law of averages]

1 hour ago, Frosty. said:

A front loaded winter appears to have gone out of the window with an increasingly mild and unsettled spell developing next week although the southeast may escape with only small amounts of rain. The generally mild unsettled spell extends to at least mid month before a split appears with some support for continuing average / mild zonality and the other option for benign high pressure to build in again but no sign of any snow being hinted at whatsoever.

I think frosty ( or should it be MILDY now  ) , has become a mild ramper...with the above assumption!! can't look that far forward with any confidence at all...especially with gfs, ecm, ukmo struggling...and my untrained is still seeing a change to more seasonal weather in F1, but until we get there we won't really know...at the moment it guess work??

Ps... 62/63 from some charts I've looked at, didn't they look similar ish ?? just saying

[ArHu3]

4 minutes ago, Law of averages!! said:

 

Ps... 62/63 from some charts I've looked at, didn't they look similar ish ?? just saying

 

http://www.meteociel.fr/modeles/archives/archives.php?mode=0&month=12&day=15&year=1962&map=5&hour=12&type=ncep

Edited December 3, 2016 by ArHu3

[law of averages]

As in similar I mean...date for date, 2nd Dec 62/2nd Dec 16....I wasn't born till 65 but my father said it was quite mild till mid month or later!!

All I'm saying we can't look to far forward with any confidence...I'll eat my hat ( and I don't have one, lol )...if a chart 2day is even 50% right in 2 wks time

Edited December 3, 2016 by law of averages

[ArHu3]

6 minutes ago, Law of averages!! said:

As in similar I mean...date for date, 2nd Dec 62/2nd Dec 16....I wasn't born till 65 but my father said it was quite mild till mid month or later!!

All I'm saying we can't look to far forward with any confidence...I'll eat my hat ( and I don't have one, lol )...if a chart 2day is even 50% right in 2 wks time

Well I just posted a zonal hell horror poster, it lasted till around the 18th just 6 days before the hellish winter broke lose. Anyway just look at the Nov-Dec 62 charts, I am not saying we'll see a repeat but I would be willing to bet that many people would say winter was over when they would see the mid December 62 charts

[Mucka]

Certainly much improved output today even if there is nothing as yet to set our stall on.

ECM and GFS ensembles show two signals in FI, the first a strong signal for a a steady decline back to normal temps which I think we can pretty much be secure on and the second, a weaker and less secure signal, for the much vaunted mid month blocking to make appearance with the possibility of some colder temperatures returning 3rd week of December.

Obviously we are most interested in the prospects of blocking and there is more than one way to skin a cat here. The first seems to be those height rises to out N/NE as mentioned previously and have the jet forced South which is probably the quicker and more secure route with the pattern amplifying behind, The second is simply for the lobe of PV setting up around Greenland to push back East setting up a mean trough to our NE that digs down into Scandinavia and Europe with ridging in the Atlantic by way of response. I think that would take a few days longer to establish any blocking and there is more danger of just getting a toppler rather than a proper block but crystal ball stuff tbh.

Obviously I am in agreement with those that say wait and see if a strong signal develops but I will be watching to see if those particular signals strengthen with a little more interest over coming runs.