Worth noting that GEM was awful again. Should be taken seriously as it predicted this spell first

 

Not that awful

-4C maxima in the SE on Saturday.

Most GEFS hold the block up, but a number do sink

THis is the best

 

Not that awful

-4C maxima in the SE on Saturday.

 

 

I mean longer term pattern, the jet overtops and normal service resumes

Still only a very small minority of runs get anything like what you would call mild at the surface by day 8 here:

There does seem to have been a slight modification from ice days to maxima of around 1C in the south though, being picky.

 

Remenants of frontal system limiting height of convection. Orography generates shallow lift/convergence.

I'd go with this. The Radar in this region has always looked odd for as long as I can remember. Sometimes with a straight line through ppn changing it from yellow and Greens to the 2 tones of blue. Never made sense.

 

I'd go with this. The Radar in this region has always looked odd for as long as I can remember. Sometimes with a straight line through ppn changing it from yellow and Greens to the 2 tones of blue. Never made sense.

I think deeper convection is trying to get going (yellows/greens) but is being supressed so most of it is just shallow stratiform precip.

Stratiform precip can give alot of snow but you need -15C type uppers to get much out of shallow convection, ideally -20C.

So deep is best.

 

I'd go with this. The Radar in this region has always looked odd for as long as I can remember. Sometimes with a straight line through ppn changing it from yellow and Greens to the 2 tones of blue. Never made sense.

There are some local oddities in the radar network. Eg I am very familiar with the triangular wedge extending eastwards in the Winchester area which usually shows lighter than surrounding areas, due I believe to ground clutter blocking that radar beam.

Still only a very small minority of runs get anything like what you would call mild at the surface by day 8 here:

There does seem to have been a slight modification from ice days to maxima of around 1C in the south though, being picky.

Yes, I noticed that and wondered if the reduced snow cover v what was being forecast might be a factor.

As for the ensembles, it does look like another week of very cold surface conditions - only 4 runs get back to average values and just a couple of runs creep up to the 'rather mild' category.

I like the reload-battleground scenario that GFS paints here:

Nice and in range... 

Now that the crucial battleground is within the 120 hours range, what are people's thoughts on the merits of the high-res models such as Arpege and WRF for tracking the likely developments? Are high-res models less good with those large-scale patterns?

I really like the detail on the WRF charts, hourly right out to 120 hours and will be watching with interest how the 6Z handles the end of the week. The 0Z looked really good for continued cold.

Meteociel - Modèle Numérique WRF-NMM 0.1° pour l'Europe

The ECM 00z clusters show only about 10% of the perturbations bringing LP in slightly more strongly with a breakdown by Monday. The others are all variations around high pressure holding to our east, with variations on exactly where and therefore whether the flow has a greater or lesser southerly component, i.e. SSE to E.

By days 10-15 there's inevitably more disagreement but still strong support for high pressure to the north with an easterly flow - around 50%. Of the rest there's more support for high pressure closer to the south and westerlies or LP in charge - around 30%. The rest are a bit of a mixture.

https://apps.ecmwf.int/webapps/opencharts/products/cluster_plot_legA?base_time=202102080000&cluster=264_360&parameter=1000

Now that the crucial battleground is within the 120 hours range, what are people's thoughts on the merits of the high-res models such as Arpege and WRF for tracking the likely developments? Are high-res models less good with those large-scale patterns?

 

I really like the detail on the WRF charts, hourly right out to 120 hours and will be watching with interest how the 6Z handles the end of the week. The 0Z looked really good for continued cold.

Meteociel - Modèle Numérique WRF-NMM 0.1° pour l'Europe

 

It's been likely (per weight of output) for a couple of days that the initial push from the low will fail. It then regathers itself for another try into next week, and it's this that either succeeds (GEM) or the block more or less holds (GFS, ECM).

The evolution is broadly the same between the 3 models - the northern blocking expands southwards through Scandinavia into mainland Europe, stopping energy from the Atlantic slipping SE'wards to varying extents (GEM the most blocked over mainalnd Europe, leading to a weaker northern portion of the block, which buckles under the eight of that big low to the west - in a really crap alignment to deny a snowy breakdown)

The GFS and ECM look disappointingly dry, though, with a SE'ly flow and the high too close to us.

 

There are some local oddities in the radar network. Eg I am very familiar with the triangular wedge extending eastwards in the Winchester area which usually shows lighter than surrounding areas, due I believe to ground clutter blocking that radar beam.

The site in question is at Dean Hill near Whiteparish, Wilts. Joint UKMO/EA site. 
There’s been issues calibrating attenuation for a while and the signal appears weaker than it should be compared with the rest of the network. The result is cones of low signal radiating out, especially east.

 

There are some local oddities in the radar network. Eg I am very familiar with the triangular wedge extending eastwards in the Winchester area which usually shows lighter than surrounding areas, due I believe to ground clutter blocking that radar beam.

I have always wondered about that as well!

I’m really enjoying model watching at the moment (not as much as lamplight watching on a snowy night but that’s for another thread)

GEFS0z has an increasing number of members indicating continuation of decent cold into the longer term, low precipitation indicates the scandi high being highly influential to our weather to me.  The members touching -15 don’t look as alone as they did a few days ago.

ECM ensemble also shows the UK between a scandi high and mid North Atlantic low pressure. It’s very interesting to see how this plays out and if we have any slider lows for that setup. 

I can’t help but smile ear to ear when I see the FI GFS 0z operational. That channel low is a sight to behold. I can’t help myself! Mustn’t get excited about that just yet

 

 

If the weather does not deliver what I would like, I console myself in that the weather (both virtually and in real time and space) is intriguing, amazing and a source of great wonder in my life. We are so lucky to be able to follow its day to day behaviour so closely.

In the meantime the MJO looks still to be in favourable territory and going nowhere fast based on GFS.

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

Still not overly mild by day 6 on the 12z GFS op:

Monday blizzard... slowly turning to rain from the south on Tuesday

Monday blizzard... slowly turning to rain from the south on Tuesday

Interesting how the breakdown keeps slipping. 

Given that par for an easterly cold spell is about five days, this one looks like being one to remember.

Also interesting how GFS keeps wanting to rebuild a Scandi HP in the longer term.