Hunt For Cold: Model Discussion - Heading Into Christmas

[Tom Quintavalle]

Yes, still too much energy near the southern tip of Greenland. On the ECM 00z we started to see some tentative height rises over Greenland but we also need to lose those stubborn positive heights to our south. But t240 only takes us to 5th Jan. Hopefully if the Strat. cards fall the right way for us here in the UK, we should start to see more positive synoptics, as we move further into January.

Regards,

Tom. 

[KTtom]

Yes, you can see at just 168 how it could suddenly switch to a cold conclusion. There is pretty good agreement at 144 for a window of opportunity around the Greenland area, gfs blasts the Atlantic thru (what do you expect) but definitely a slightly better trend for our high to get slightly further north..

 

[IDO]

The GFS op and Control still showing zero signs of any QTR out to D16. The PV having free reign to move around to the north cutting off any fledgeling weak height rises. The op and control suggest around D9-D10 we move into a more zonal flush whereas the ECM and GEM continue with UK HP:

We know ECM D10 charts are to be treated with caution when showing blocking against the other output so any random goodness from them needs to be backed up before I start calling QTR!

The GEFS is trending down on the 850s but looking at the wind direction zero activity from the SE, E or NE so we are relying on low uppers crossing in from the NW for these and that for many just won't wash:

Clearly, the ECM on this run has backtracked on any Pacific ridging, something the GFS has moved away from a while back. So the Tropical waves not really showing up to D10 (or D16 GFS). We may not want to hang our hat on trop led cold:

ECM: 

Looking at all the D10 charts none are moving in the right direction. Of course snapshots at D6 etc may hint at "potential" but we only have to look at subsequent frames to conclude that is as far as it goes as the PV -v- wave battle remains fluid, neither going for full victory.

Thankfully it is only a matter of time before we get blocking further north although we are still waiting for a definitive sign that the SSW will be major enough to kill the strat PV? With less than hoped for trop led help I am not as decisive as a week or so ago.

 

[SMU]

Lots of upgrades overnight - especially UKMO pushing heights into Greenland, 168 will bring the -10 line close to the NE & -8c probably more widespread -

ECM close but no cigar- but not to concerned when the 120-144 period is still subject to high levels of change

We are seeing a QTR develop here noting the big + PNA block & atlantic ridge- GFS will be about 2 days behind due to crappy resolution, same as December..:

Edited December 26, 2018 by Steve Murr

[Frosty.]

A decent effort from the Ecm 00z..at least it's something interesting to look at compared to the dull as dish water output recently!!..happy boxing day.

[IDO]

23 minutes ago, Steve Murr said:

Lots of upgrades overnight - especially UKMO pushing heights into Greenland, 168 will bring the -10 line close to the NE & -8c probably more widespread -

ECM close but no cigar- but not to concerned when the 120-144 period is still subject to high levels of change

We are seeing a QTR develop here noting the big + PNA block & atlantic ridge- GFS will be about 2 days behind due to crappy resolution, same as December..:

2

The PNA is positive throughout:

In fact, quite a strong positive PNA period showing up, hence why I believe the flush that flattens the UK high maybe correctly modelled on the GFS? Of course, if the background signals are wrong then all change, but based on the current output no N Pacific blocking and likely a flattening of the Atlantic Ridge (HP cell)?

[Interitus]

1 hour ago, Ali1977 said:

Indeed, Split followed by the Houdini strat. 

Oh no, there it is look

[Sky Full]

11 hours ago, feb1991blizzard said:

Im hoping that Dumping, Dolloping,Belting, Tonking, Pasting, Stonker and Hiding are going to become the buzzwords over the next few weeks.

If they're the names of the NW seven dwarves then it's bound to be Snow White everywhere!  Here's hoping!  

At least we can expect some settled weather over the next few days into the New Year according to current output.   That's got to be better than a raging Atlantic with storms, gales and pouring rain.

[nick sussex]

The UKs cold forcefield desperately trying to hang on with the ECM being the mother of all teases !

Plenty of cold air to the ne if only the upstream troughing would amplify . 

You can see the issue , a lack of any trough disruption . Hopes rest on that between day 6 and 7 .

There are some differences upstream with the handling of shortwave energy moving east towards the Great Lakes , this will eventually interact with the troughing to the west .

 

[SMU]

25 minutes ago, IDO said:

The PNA is positive throughout:

In fact, quite a strong positive PNA period showing up, hence why I believe the flush that flattens the UK high maybe correctly modelled on the GFS? Of course, if the background signals are wrong then all change, but based on the current output no N Pacific blocking and likely a flattening of the Atlantic Ridge (HP cell)?

My post was highlight the developing +PNA - to a high amplitude-

+PNA / -NAO Can work - remember GFS hasnt resolved the pattern yet - ECM OP & UKMO 48 hours ahead - EPS about 24 hours ahead

Look at the last 3 00z EPS mean

24th (192) then 25th (168) 26th (144)

The GFS has made 'some' swing today but its about 24-36 hours behind.

Also note how sharp the UKMO 168 is -

[Methuselah]

Still eleven GEFS T850 ensemble members finishing up below 0C:

[Radiating Dendrite]

11 minutes ago, Ed Stone said:

Still eleven GEFS T850 ensemble members finishing up below 0C:

Yes, but not many getting under the all important -8c.

[frosty ground]

7 minutes ago, Radiating Dendrite said:

Yes, but not many getting under the all important -8c.

When did -8 become important 

[swfc]

11 minutes ago, frosty ground said:

When did -8 become important 

Is it a 850s chart? If so 0 won't cut it

[SMU]

Icon 120 the best yet from this model -

[Radiating Dendrite]

13 minutes ago, frosty ground said:

When did -8 become important 

It is often touted as the magic number for snowfall. I know there are a million one other factors and you can get snow at -1c 850s or rain at -10c but as a general rule of thumb anything less than -5c in the UK at low ground just doesn't cut it.

[Methuselah]

2 minutes ago, swfc said:

Is it a 850s chart? If so 0 won't cut it

It is indeed, swfc - but I was only intending to show the overall decline; and, as the run goes out to nowhere near mid-January, it's unlikely to show anything in terms of dramatic change...Until mid-month, changes on the ground mightn't be all that stark...Time will tell!?

[stratty]

28 minutes ago, frosty ground said:

When did -8 become important 

.......when they're all coming from a westerly direction!

[bluearmy]

interesting output .....reaching a stage where gfs strat output is better than ec at 10hpa! I’m sure the models will come together on this - fwiw, that ec op run was a better split at 30 and 50 hpa but didn’t make it at 10hpa until the end of the run. The zonal flow chart from yesterday’s 12z looks a bit meh on the Berlin site with the reversal working down but recovering positive at the back end very top. the days 9/10 low down look a bit odd. Much to still be resolved up there ! 

Ec becomes extended Atlantic dominated and looks to need to push the trough through behind the end of the run into the scrussian trough (which looks weaker). The spreads at day 10 say that this surge of low heights into the Atlantic day 10 may not be quite so straightforward and we could develop that block to our north ....... there doesn’t seem much that isn’t on the table at the moment ...

and the loss of the Icelandic clusters is really peeing me off ! 

Edited December 26, 2018 by bluearmy

[DanDorsetUK]

Already better heights on 6z gfs as early as T96. Collapsed quicker on this run. 

Edited December 26, 2018 by Rapodo

[johnholmes]

Using the usual 500 mb anomaly charts for an update. Below my usual notes from my anomaly file

Almost a week later Boxing Day

Ec-gfs both show ridging but differing positions/shapes, ec shows marked troughing into Europe, gfs does not

Noaa is more like ec re position orientation etc of ridging and does show troughing into Europe (well east)

No 3 model agreement although noaa and ec are pretty similar. I would always back these two anomaly charts against gfs so their idea if probably what we will see in the upper air air pattern 6-10 days from now. Nooa 8-14 also similar so 6-14+days the ‘mean’ charts may show this pattern and roughly the positioning although that may show some differences.

No major signal so far of deep cold into the uk area in the next 2 weeks but confidence is not much more than 50% at the moment.

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

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

Looking at the GFS MJO and possible 500 mb patterns. It is in 5 at the moment and predicted to go into fairly high orbit in 7. Taking this to occur in January suggests that 500 mb ridging in the Greenland area and south to the west of the Uk as being the most likely. So 'perhaps' some indications that the ideas of 7-10 January for a marked change have some degree of of support.

Edited December 26, 2018 by johnholmes

[nick sussex]

Better trough disruption this time on the GFS 06 hrs run .

Its a shame that shortwave energy nw of Iceland takes so long to clear east . There is a window of opportunity because of the amplification upstream . 

Key timeframe day 6 into 7 .

[Weathizard]

We have a weak ridge heading into Greenland at day 7, the way this is setting up will lead to a more mobile pattern as opposed to a colder pattern IMO

[SMU]

Its catching up....

Note the residual heights over greenland now @180...

The first step in the right direction from the GFS

[DanDorsetUK]

It's actually a better run despite the heights dropping quicker there is a path opening! Look north east pv dropping. Big sudden changes in the gfs now being seen I feel.

Edited December 26, 2018 by Rapodo