Model Output Discussion - 05/01/2016 18z onwards

[john mac]

Just now, blizzard81 said:

The problem is the 12z ukmo is a slight downgrade on it's 00z this morning. What does that tell you?

It's much more consistent than the other two models 

[Methuselah]

The last time I heard, momentum (p) = mass(m) x velocity(v) (p=mv)..And that, IMO, drives the synoptics. Synoptic forecasts cannot drive momentum?

[blizzard81]

Just now, john mac said:

It's much more consistent than the other two models 

Consistency is all well and good but only if it is correct!

[Jason M]

15 minutes ago, SLEETY said:

be back to dec if that comes off,good job it 10 days away and wont verify anyway.

It's a long way off, granted. I don't share your confidence that it won't verify though (at least in terms of the general pattern).

for the last day or so the GEFS have been highlighting an increasing trend towards a strong build of pressure to our south. This has been moving smartly through the timescales and is now signposted nicely in the last few opp runs of the GFS (and the high res part as well!).

IMHO I think a return to the status quo is quite likely. That said, plenty of weather before then, and some snow for many this week. 

Plenty of time to for the charts to change but the background signal to this winter is high pressure readily building to our south and I'd not be at all surprised if it reasserts it's influence.

 

Edited January 10, 2016 by Jason M

[Weather Boy]

Just now, blizzard81 said:

Consistency is all well and good but only if it is correct!

Yes, there has been a lot of discussion about consistency, but I recall a year or two ago, Fergie saying that consistency does not a good model make and therefore consistency should not be taken as equating to accuracy!

However, a very inconsitent model is bound to be accurate occasionally, if it comes up with every possible solution!

[john mac]

2 minutes ago, blizzard81 said:

Consistency is all well and good but only if it is correct!

Ahh the beauty of model watching. An intriguing weeks weather coming up!

[Stuie]

Haven`t posted in a while but our friend the JS not doing many favours in stopping any flow up from the SW next weekend.

[nick sussex]

6 minutes ago, Ed Stone said:

The last time I heard, momentum (p) = mass(m) x velocity(v) (p=mv)..And that, IMO, drives the synoptics. Synoptic forecasts cannot drive momentum?

I think your emoticon is apt. I thought you'd finished the Christmas sherry by now! lol NWP is mathematical equations allied with starting conditions which produce the synoptics we see. Momentum is just that momentum, all weather entails different synoptics, synoptics tell us what weather to expect. Momentum if you're talking of where the energy is transferred from and to is a different matter. The reason the UKMO is the better output is because its synoptics allow for your argument re momentum cold momentum but momentum does not drive synoptics,the synoptics allow that expression of momentum. Anyway this is far too heavy for a Sunday night! lol

Edited January 10, 2016 by nick sussex

[Frosty.]

Every cold day in winter is a good day as far as I'm concerned and this evening's Ecm 12z shows plenty of good days and nights for coldies with increasingly widespread and sharp frosts, icy patches and snowfalls in various parts of the UK, this run shows cold surface conditions almost to the end of the run further southeast..Enjoy it

[JOPRO]

I really think we shouldn't be worrying about what the models at showing after 120-144 hrs, what is agreed on is that we are looking a cold shot from Wednesday through to Saturday with a very good chance of snow. Beyond that is unknown as we lack and real concrete consensus between the models (yes we have some similarities but nothing you would bet your house on), those making statements about a return to Decembers abomination are very bold indeed. Still fascinating viewing and far from a done deal for a continuation of cold or a returne to mild. Anyone else feel a gfs upgrade coming later???

[Winter Cold]

Well GFS 12z takes another leap upto the mild end of the ensembles from the 17th, just about the mildest one. Its been doing this for many runs now. The control follows it aswell..so pretty consistent.

ECM is a worry this evening as it too doesnt look as good and is also moving the cold uppers away by the end of the weekend.  A vervous wait now to see where it sits within its suite..

I have to say im shocked that we could be looking at the GFS picking out the correct pattern twice in one week!!! Never thought id hear myself say that lol. At the same time, my confidence has been shaken in the UKMO model, well see it if it backs down for the second time this week in the morning.

The one bit of salvation atm is that the poorest charts are at the end, so plenty of time for change

[blizzard81]

1 minute ago, Weather Boy said:

Yes, there has been a lot of discussion about consistency, but I recall a year or two ago, Fergie saying that consistency does not a good model make and therefore consistency should not be taken as equating to accuracy!

However, a very inconsitent model is bound to be accurate occasionally, if it comes up with every possible solution!

Yes, but there is nothing worse than a model that is consistently wrong - think nogaps, cma and more often than not, gem. Are we about to add ukmo to this miserable list?

[Ben Lewis]

I'm just going to enjoy a week of more seasonable weather with a possible snow fall, whether that be with showers or something more organised. 

Just look how much can change within 5 days.. We've gone from Black holes and a strong block, to a slack northerly followed by a return to the sauna pump.. who knows what the models will churn out come Thursday/Friday. 

[karlos1983]

I'm sorry, but until such time that all 3 models are in agreement on how the Azores low is dealt with, we can't really say with any confidence which is correct, all three still pretty much disagree (GFS/ECM/UKMO) although the ECM and GFS agree that it will phase with the lobe south of Greenland, just down to timing. 

I don't think currently any model can be disregarded just yet. I think as Nick said a little earlier, for sanity think ECM, but I guess that's down to individual choice, I know I will be.

so we have GFS discounting any extended cold in the midterm and the UKMO sticking it's fingers up at that idea, with the ECM sitting on the fence, that's how I see it.

144 ECM/GFS/UKMO

[Guest]

4 minutes ago, Winter Cold said:

 

I have to say im shocked that we could be looking at the GFS picking out the correct pattern twice in one week!!! Never thought id hear myself say that lol. At the same time, my confidence has been shaken in the UKMO model, well see it if it backs down for the second time this week in the morning.

 

UKMO doesn't even go out that far, and their extended written forecasts have been consistent in stating a likelihood of a return to a westerly regime with temperatures returning to average/slightly above average.

[East_England_Stormchaser91]

Everyone going on about southwesterlies on the ECM at the end. 

For a start, especially in the south, that will not be as warm as it suggests. S/SE winds coming in from the cold continent. That Is also a mid latitude block too, with very displaced potent cold below it stretching from turkey to spain! 

Would not take much for that high to retrogress under the circumstances shown. 

[chionomaniac]

So unsurprisingly the GEFS centre a strong positive H500 anomaly over the UK by day 10. This will certainly be welcome over the country and hopefully a bit of drying out may occur. Even though the 850's may be on the rise surface temperatures may not be so depending upon the orientation of the high.

 

 

By day 16 more surprisingly, there is a hint of positive anomalies again towards the southern tip of Greenland. One to watch hey?

 

Weatherbell anomaly charts

[Winter Cold]

5 minutes ago, CAPE-steve said:

UKMO doesn't even go out that far, and their extended written forecasts have been consistent in stating a likelihood of a return to a westerly regime with temperatures returning to average/slightly above average.

It doesnt go out as far as the other two no, but the differences are at 120-144 and its very different at the time frame now. The high is still holding on much further north which results in the better profile for the UK.

Thats as how I understand it anyway

[chris55]

De Blit 10 day ens just highlights how the surface cold hangs on even at day 10 with the milder uppers moving iver.

[tight isobar]

One thing I think we can all agree on here....

FI is atm in much nearer time frames.....given divergence! 

Ponder @144hr..for the next +76hrs...

[phil nw.]

Whilst we have the difference in the Atlantic from day 4 with the UKMO i am keeping an open mind on the placement of the weekend high.Certainly GFS persists with sweeping the cold away quite quickly while the ECM may buy us an extra day or 2 of surface cold but the reformed Greenland vortex looks ominous at that stage on both models.

I did post late last night alluding to my concern that later naef.s and ecm ht anomalies were draining  away the Arctic heights and trending to raise pressure to our south.If this continues then of course a cold pattern can't be maintained.

I do wonder if the UKMO can snatch at least a draw out of this by sending more of the jet south and at least holding any heights around the UK in the hope that another Atlantic wave pushes heights poleward again.

ECM at T192hrs tried this but because of the earlier linking of the Azores low with the Canadian energy it is too late and is overwhelmed by the re-energised northern jet.

The hope lies with the UKMO run because the jet is split earlier upstream more in our favour.Less energy goes across the north and we would have a shot of a better build of heights around the uk/nw europe later.

Of course this is all speculation as we don't see the UKMO model that far.

I guess we need to remember that this current cold nationwide was only ever modeled to start around the 12th and last around a week so any delay to mild would be a bonus and may buy some time for another attempt to re-enforce the cold.

The way to look at this is that we have a week or so where we will see the coldest period countrywide so far this season with the unfamilar forecasts of frosts, and if we are lucky, some snow.

Whatever happens we can't control the weather,nothing is firmed up beyond the next 4 days or so- just enjoy and embrace the drama.I am sure there's more to come!

[Frosty.]

Keep positive guys, the ukmo 00z / 12z show we could have a very nice cold spell which lasts well into the following week, there's still plenty of uncertainty.

Edited January 10, 2016 by Frosty.

[Stuie]

10 minutes ago, East_England_Stormchaser91 said:

Everyone going on about southwesterlies on the ECM at the end. 

For a start, especially in the south, that will not be as warm as it suggests. S/SE winds coming in from the cold continent. That Is also a mid latitude block too, with very displaced potent cold below it stretching from turkey to spain! 

Would not take much for that high to retrogress under the circumstances shown. 

It`s not soo much about southwesterlies, it`s what happens to the Azores. The Jetstream could still promote a northerly Atlantic ridge (UKMO) rather than a NE (GFS/ECM). Weirdly still up for grabs and would like to think that could happen but the heights over Scandi want to crumble on the GFS and can`t see anything to stop a Westerly flow. (SW).

[snow mad]

10 minutes ago, chionomaniac said:

So unsurprisingly the GEFS centre a strong positive H500 anomaly over the UK by day 10. This will certainly be welcome over the country and hopefully a bit of drying out may occur. Even though the 850's may be on the rise surface temperatures may not be so depending upon the orientation of the high.

 

 

By day 16 more surprisingly, there is a hint of positive anomalies again towards the southern tip of Greenland. One to watch hey?

 

Weatherbell anomaly charts

This time a few days ago the anomaly charts were showing black holes which almost disappeared over night so I don't think I'll be staying up late waiting to see what happens. Just weather but it has been very disappointing to see this cold spell downgraded so much!

[Harsh Climate]

I think a lack of posts from a certain 2 members, really says it all... 

 

Poor output from the 12z's after something a little more promising overnight. I would now have the chances of milder atlantic weather winning next weekend/monday after at 70% now. All hopes pinned firmly on the UKMO

 

Yeah some places may see a little snow, but from what looked an epic cold spell will just be a standard uk cold spell..  (don't know why that last sentence is underlined or how to remove it lol.)

Edited January 10, 2016 by Harsh Climate