Kasim Awan

Looks like January 2013 to me.

192 ❄

Yes, all output has shifted to the GFS at day 6/7.

We can start analysing the path now. Historically these features are picked up fairly accurately at lengthy timescales.

I think a slight downgrade in the synoptics / high latitude pressure has increased the risk of very disruptive snow events. This is because this allows more moisture to be fed into the south of the UK.

The potential is there for a bout of significant, heavy snow events 16th-19th before development of a cold inversion towards 18th/22nd. This is probably the most likely outcome at this point. However, we need to be steady as the phasing to our south west looks slightly less optimal than it did a few days ago, and so it wouldn't take much to scupper the cold flow entirely at this point.

I think we need to wait until this next chance of a very cold north easterly comes into the 168h time frame as there is a real risk it will be downgraded as the models correctly model the strength of the Iberian high within a more reliable time frame. Nevertheless the general outlook is cold and wintry.

Output has improved for 168h-210h however the 120h-168h has once again downgraded, I'm not a fan of these pesky medium term downgrades. However there is still a very decent chance of a significant cold spell.

Yes but the UKMO has moved to the GFS more than the contrary. So we need to be realistic and factor in potential significant warm sectors here. There is still a real risk of heavy snowfall.

A definite trend towards the GFS this morning with the UKMO, ICON and GEM now all introducing a warmer sector behind the initial northerly around 16th of January. This is not a "cold spell is over" type post - just an indication that the cold spell will likely have a warmer sector during this period. It also raises some concern for warmer sectors going forwards as this setup reduces WAA into Greenland significantly.

80/20 is fair enough I am at 65/35.

No we can't just bin output showing us what is physically possible given it wouldn't take much to get to GFS/GEM point on current UKMO/ICON solution. Weather forecasting is not black and white it is a probabilistic assessment.

I wouldn't say definitely yet let's get this within 120hours.

ECM going the ICON/UKMO route which switches the balance in favour of this outcome.

Not sure about this I think the Greenland high signal looks less amplified and robust than a few days ago.

Yes cold is nailed on snow is nailed on but the detail is not i.e. where how much and when are not especially as now we see ourselves facing a messy complex synoptic pattern.

GEFS/GEM and now the ECM has moved North. I think you are misreading my posts slightly I am not claiming the cold has been shunted away just that the dynamics now look slightly different with more influence from the South West / sliders as opposed to textbook northeasterlies. The issue we run into (which could also be our fortune) with such a pattern is the proximity of milder air to the south. Temporary milder incursions aswell as a more robust push cannot be conpletepy ruled out I would like the GFS/GEM to move towards the ECM later today. The ECM00Z shows where the sweet spot is with the push from the South West. This is a finely balanced, changeable synoptic of which to say is nailed on this early is not particularly realistic in my view.

A clan of balanced views.

Didn't overreact the low and a push of mild uppers is still a concern following the initial nailed on Northerly. Objectively analysing model output is not an overreaction. Any push will bring in a front with an easterly wind and so introduce a likelihood of heavy snow so there is a reward here either way. Yes ECM outcome still slightly in favour over GFS/GEM but we can not discount it entirely.

ECM throwing out a snowstorm this morning.

Steady on ECM could still go either way here as it does not cut off the flow into the Azores area.

No I don't. Synoptically it is the cause. It is a symptom of climate warming but that is not a synoptically significant mechanism. The current concern wouldn't be present if there was more room for low pressure to move South in that area.

High pressure at 500hpa and 500hpa flow more important.

Yes this is true. Thankfully the ECM/UKMO are adamant on a more expansive mid Atlantic ridge with a more easterly cold push and therefore do not strengthen the Azores low / Iberian high.

We shall agree to disagree I see a localized intensification of the Iberian / Mediterranean high as the main issue.