The Enforcer

-5.1C now just after 6:30pm. EDIT: By comparison, it was 1am before it reached that figure last night.

-4.2C by 5pm.

-3C by 4pm.

I think that's the most disheartening thing about cold spells, when a chart like this: appears in model runs it gets 'boomed', but it only results in rain for many people.

I haven't seen any cloud since first light yesterday and I'm about as far as you can possibly get from any of the shower activity on any of the coastlines.

The snag with that is that UKMO was an outlier at T+120 in relation to apparent wind direction and strength compared with the other models.

Tempting, but it did go back to +0.1C for a little longer. The drop has started though so down to -0.4C already. It ought to be colder tonight as a result of the lower maximum, unless anything dramatically changes.

Just got to 0.1C after being at 0.0C for over half an hour. No ice day. And back to 0.0C a minute later. You couldn't make it up.

Time for another T+120 comparison: GFS 06z ECMWF 00z UKMO 00z JMA 00z ICON-EU 06z GEM 00z NAVGEM 00z All looking fairly similar with Low to SW and flow from N over the UK, the exception being UKMO where Low is to S & SE and flow is from NE.

But, with 48 GFS runs to go an average southwards shift of 5-10 miles per run would paint an entirely different picture by T+0.

@Liam Burge did you manage to see any falling/settling snow?

Overnight low got below -8C and still only -4.3C. Ice day should be possible.

And -6C just now. Provided no crappy cloud appears out of nowhere, this would overtake last night's minima and could end up significantly colder, if it keeps steadily dropping before daylight.

I got down to at least -5.1C before another thermometer malfunction.

Really getting its act together now:

As of midnight: Was it forecasted? WRF-NMM 2k 18z - not bad WRF-NMM 0.05 18z - a bit too coastal UKMO HD 12z - largely coastal ARPEGE 0.1 18z - largely coastal ICON-EU 21z - only coastal UKV 21z - needed more precip All have picked up on something happening in the area, but most have underplayed the inland penetration and/or amount of precipitation.

Bit of a line forming:

Incoming top left:

Thanks. Fixed now.

Here's a comprehensive T+120 rundown: JMA12z ICON18z GEM12z NAVGEM12z UKMO12z ECMFW12z GFS18z Variations of undercutting with a N/E feed over the UK, except for GEM.

After some thermometer malfunction earlier I can currently report -4C.

Unless the precipitation is to the north of the UK, it which case it doesn't budge.

This chart is more laughable.

It is laughable how far one would have to travel from one of those bare patches in the UK to find a bare patch in another European country.

I was thinking earlier that the models don't seem to 'like' a synoptic pattern where the UK is in this sort of no-mans land, where it is cold, but in a slack rather than direct feed, so not excessively cold or snowy compared with historical precedents. They seem hellbent on breaking this pattern at the first available opportunity, usually with an extreme solution - hurricanes, spanish plumes at one extreme and chunks of polar vortex from the Arctic/Siberia at the other end of the spectrum. A model may run with variations of the same extreme for a few runs, so seemingly it starts to gather support within its ensembles and some credence. This appears to come to an abrupt halt when the proximity to current data eventually makes the model's extreme solution impossible at which point it shows the preservation of the existing pattern for a bit longer, with an alternative exterme change being introduced a couple of days later. Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4759100