Hunt For Cold: Model Discussion - Heading Into Christmas

[bluearmy]

24 minutes ago, Steve Murr said:

So off we go on the 06z GFS...

Im sure this will be the first run to smooth across into the Icon...

You’re optimistic !

i expect the 33% of extended eps which were holding the trough back will be there again .....perhaps a little larger ....

doesn’t take much of a leap of faith to see some wedges and sliders introduced into the mix if the full ridge fails .......still no QTR evident across the NH but if the slowing zonal flow allows that Atlantic ridge to gain enough traction then we are in a good place as the month progresses and the first wave downwells  

going back to ICON, it was good in feb/March, especially to our ne. but gfs ops weren’t as solidly zonal back then as they currently show - mind you, when there is a mobile flow on the market, gfs is only going one way! 

And as alluded earlier, the gefs may be picking up that wave by mid month on the 00z suite ........

Edited December 27, 2018 by bluearmy

[shaky]

29 minutes ago, Steve Murr said:

So off we go on the 06z GFS...

Im sure this will be the first run to smooth across into the Icon...

Early changes 06z!!more of a ridge between the low coming out of the states and the low across southern greenland at 84 hours!!could make a difference!!

[TEITS]

Pretty clear to me that any charts beyond +168 might aswell be thrown in the bin at the moment. This is because the models (except GFS) are swinging towards the high pressure building further NE than expected and thus possbily bringing a much colder NE,ly flow. At the moment the chances of a much colder NE,ly are increasing but still changes need to occur for this to bring snow showers.

If the high continues to be upgraded i.e building further NE then this impacts what happens afterwards. What I mean by this is low pressure could go underneath the high pressure rather than over the top sinking the high.

[Day_9]

I know NOTHING about reading these outputs but i have keenly lurked here fir a number of seasons.  The ICON has been nailed on the last 2 winters and in the ever uphill struggle in the UK, it is the only one offering us hope.  Off the back of it’s consistency in recent years, lets hope it’s right again!!

[winterof79]

ICON 06Z actually colder air shunted south than the 00Z

Nice little low forming N/E Scotland dragging down colder air here is 06Z

00z

[That ECM]

Improved again

[karlos1983]

Just now, That ECM said:

Improved again

Yup it’s a bit like Saturday at the Masters this morning! Moving day is here ?

[markw2680]

Lol don’t no about anyone else but it’s a little annoying when you get rolling commentary like 06 is not as good then literally the next comment is actually ignore that it’s better etc. Let the run at least get going before comments like that please

[karyo]

1 minute ago, markw2680 said:

Lol don’t no about anyone else but it’s a little annoying when you get rolling commentary like 06 is not as good then literally the next comment is actually ignore that it’s better etc. Let the run at least get going before comments like that please

I find the rolling commentary is the best thing about netweather! 

Anyway, the 06z makes a shift towards the ECM which is good to see.

[IDO]

13 minutes ago, TEITS said:

Pretty clear to me that any charts beyond +168 might aswell be thrown in the bin at the moment. This is because the models (except GFS) are swinging towards the high pressure building further NE than expected and thus possbily bringing a much colder NE,ly flow. At the moment the chances of a much colder NE,ly are increasing but still changes need to occur for this to bring snow showers.

If the high continues to be upgraded i.e building further NE then this impacts what happens afterwards. What I mean by this is low pressure could go underneath the high pressure rather than over the top sinking the high.

5

I think if we have learnt anything in the last few years is that the ECM op is temperamental in HP situations. For some reason the op clusters in the most extreme "cold" outcome. To take the ECM at face value flies against that experience. Looking at the ECM mean at D10 compared to the op would be wiser especially as it verifies far better. D10 mean:  compare D10 GEFS: 

Looking at those uppers scrapping the Eastern UK at D8 compared to the mean:

Again we see the Op as the best case scenario comparative to the mean and of course they usually meet somewhere in the middle at best, which isn't that promising.

From my perspective, the ECM op can be at its worse in such situations and too many garden paths have needed to be replaced for me to walk that route again.

 

[karlos1983]

14 minutes ago, karlos1983 said:

Yup it’s a bit like Saturday at the Masters this morning! Moving day is here ?

Hmm rain stopped play on the 7th..

[Methuselah]

Here's the GEFS T850 graph for Northamptonshire: the mean declines throughout the run, post January 1st, though it's clear from the spread that things remain far from being resolved...

[SMU]

GFS swing about 3/400 miles west 00z > 06z 

We will need about 5 -6 more runs to be the like the icon !

[Iceaxecrampon]

[IDO]

3 minutes ago, Ed Stone said:

Here's the GEFS T850 graph for Northamptonshire: the mean declines throughout the run, post January 1st, though it's clear from the spread that things remain far from being resolved...

It looks more dramatic as we are currently in a very mild upper air pattern:

At the end of the run, the mean 850s are basically just in line with the seasonal norm. Their sine wave nature just suggests the timing of mini-ridge -v- mini-trough. Looking at the GEFS wind direction, none from the Easterly/N/NE/SE quadrant, the preferred directions for sustainable cold and snow?

[snowblizzard]

Slug drifting East!

Allowing more in the way of Atlantic influence!?

So frustrating that UK is always in the yellow wedge!

Edited December 27, 2018 by snowblizzard

[DanDorsetUK]

Surely it's still safe to assume there is no ssw being picked up by the models yet. We are still to far out. The gfs yesterday gave a slight glimmer of breaking up the pv in fi. I'm going to say by next Sunday or Monday the ssw will start to show at the earliest. A default reset might not be so bad before the main event. 

Edited December 27, 2018 by Rapodo

[nick sussex]

It’s a shame the GFS is dragging its heels .

Very welcome improvement from the ECM though after last nights run. In terms of the upstream pattern NCEP still think the GFS and GEFS are too fast .

They mention that the GEFS mean is around 10 degrees longitude further east , roughly around 700 miles .

Edited December 27, 2018 by nick sussex

[Weathizard]

5 minutes ago, Rapodo said:

Surely it's still safe to assume there is no ssw being picked up by the models yet. We are still to far out. The gfs yesterday gave a slight glimmer of breaking up the pv in fi. I'm going to say by next Sunday or Monday the ssw will start to show at the earliest. A default reset might not be so bad before the main event. 

Heard that one before, then the Atlantic train gets going and washes away a month of winter! ‘Zonal default’ or reset pretty much never works, on the SSW effects I’m sure modern models take into account stratospheric conditions.

The GFS is bloody dreadful, flat as a pancake even at 240.

[carinthian]

3 hours ago, carinthian said:

UKMO certainly best of the models this morning as the NH profile chart indicates. A build of cold air just to the NE of the British Isles and you would expect the West Russian trough squeezed between the Siberian High and the UK high to start to push SW into Europe. GFS horrid, ECM sort of half way house. More expanded data coming into day , so this evenings runs could be big in your hunt for cold.

 C

 Out of interest , I have been informed that our resort planners have just been given advanced warning of possible severe cold to affect Central Europe by the first weekend of January with very low temperatures forecast in the mountains. I am not out there at the moment so cannot provide much further information BUT will not be based on the GFS outputs. Something is stirring , I feel.

C

[Summer Sun]

The 00z ECM op was off the scale quite literally with the cold air in early Jan

 

Edited December 27, 2018 by Summer Sun

[bluearmy]

6 minutes ago, Rapodo said:

Surely it's still safe to assume there is no ssw being picked up by the models yet. We are still to far out. The gfs yesterday gave a slight glimmer of breaking up the pv in fi. I'm going to say by next Sunday or Monday the ssw will start to show at the earliest. A default reset might not be so bad before the main event. 

that shouldn’t be the case ..... you are looking at the same model of the atmosphere, whether it be at 500 hpa or at 10 hpa .... the hip bone is connected to the thigh bone etc .... we saw last feb that th gfs ops began to blow up the scandi ridge about five days before it was modelling the reversal to begin at 10 hpa. The reversal has already begun across the high latitudes above 2hpa so it’s in the starting data .......my expectation is that the slowing zonal winds are still to be taken fully into account ( the growing Atlantic ridge) but that there seems little chance of a hemispheric wave response ahead of the usual 9/14 days which should begin to show at the back end of the gefs/gfs eps and gems now .

[DanDorsetUK]

T324 yes I know but that is the likely position a ssw will be starting to show on gfs and that in my opinion is a great chart going forward. I'd expect to see major changes come next week just because the charts or not showing any real effects from a ssw now doesn't mean it won't come next Monday at the earliest. I'm keeping optimistic were see sudden changes yet.

Edited December 27, 2018 by Rapodo
Wrong chart

[Gael_Force]

36 minutes ago, IDO said:

53 minutes ago, TEITS said:

 

I think if we have learnt anything in the last few years is that the ECM op is temperamental in HP situations. For some reason the op clusters in the most extreme "cold" outcome. To take the ECM at face value flies against that experience. Looking at the ECM mean at D10 compared to the op would be wiser especially as it verifies far better

The day 10 op progression is something that was suggested by the full ensemble suite from last weekly set.

[snowfish1]

15 minutes ago, Rapodo said:

Surely it's still safe to assume there is no ssw being picked up by the models yet. We are still to far out. The gfs yesterday gave a slight glimmer of breaking up the pv in fi. I'm going to say by next Sunday or Monday the ssw will start to show at the earliest. A default reset might not be so bad before the main event. 

With you on that one 100%