The Enforcer

Two events spring to mind: 1) January 2010 - an LP developed along the line of a south-moving weak cold front, bringing a red warning here and the heaviest snowfall for decades; 2) Last Saturday - cold front shown/described as a "narrow weak band" by the BBC forecast only the evening before gave a few hours of torrential rain and flash flooding. Definitely worth keeping an open mind.

In the shorter term, 12z GFS has boosted the snow potential compared with 06z GFS, the example below being at T+24. Will the hi-res models follow suit?

Fortunately, only a few hours of favourable conditions within the remaining winter period (and spring if you don't care when the snow falls) are required to produce a decent snowfall.

Agreed. I have made a note of the timeslot and will check back on Friday to see if it is still there.

Make a note of the date and check back in at the end of this coming weekend. If it's still showing on those charts, then it's worth looking into the detail.

It strikes me that the most efficient approach when spotting a cold trend way out would be to make a note of the date and then come back 10 days later to see if it is still there.

The trouble is, most aren't even looking at the problem. The problem is that in winter there's cold countries, then there's mild countries, then there's a tonne of crap, and then there's the UK. It's an unfair game. Every winter many are trying to find a direct replacement for 1962/63 and I tell you we can't do it. Now, what we might be able to do is recreate elements of it within a mild winter aggregate.

Any excuse to get the paint brushes out: When was the last time such notes could be made over the festive period?

Unless the likely conditions are "misty"?

A low-resolution model cannot be relied on to pick out accurate snowfall 5+days out. In November 2021, even the high resolution models at the beginning of that weekend said any snow threat here would be on Saturday 27th November 2021 and that Sunday 28th November 2021would be dry. It snowed on Sunday 28th November 2021. There are 16 runs before Sunday, so these forecasts are likely to keep jumping about all over the place before then. T+0 forecasts are often wrong when it comes the the very basic question of wet vs dry and snowfall is an infinitely more complex question to answer. It's good to be in with just a shout at Xmas for once.

Forecast for this morning as of last thing yesterday: dry and increasingly sunny Actual: Rain Unbelievably crap again.

Think again. Getting perilously close even to here. Heaven forbid we could have a day when washing could actually dry outside. I don't know why BBC even bother making forecasts when they are so far out at such close range.

Saturday morning forecast from yesterday evening: sunny. Made plans to go out. Actual: rain. Crap again.

To really rub it in earlier today I saw that there were some snow showers moving from a south-easterly direction on the radar, but even these were only affecting the north and east of the UK.

Shame this evaporation doesn't work on rain. Probably be flooded again before the month is out.

And watch it all evaporate before it hits the ground. #coldspellsthathateyou

I wonder if I have been suffering from a microscale version of that. I am about 400 metres to the east of the River Thames. Could the easterly wind crossing the water be responsible for daytime temperatures well above the forecasted sub-freezing levels?

I am not surprised by the snow performance so far as this seems on a par with what easterlies delivered here in 2010 and 2018. The shower bands need to align themselves perpendicular to the isobars, which is what they do in almost every other type of precipitation situation. Unless some sort of organised front/trough/small low develops in the flow, we are highly unlikely to see any material accumulations. The biggest disappointment has been the daytime maxima, both yesterday and today getting above 2C, when sub-zero was modelled. I think the very least I would expect from this cold spell is for some significant falling and settling snow during the transition back to mild, even if it melts fairly soon afterwards. The 'breakdown' ought to have the ability to deliver a significant period of snow as from the modelling I have seen, the cold air only retreats slowly and continues to draw up surface cold from the continent as it does so, meaning that temperatures should only rise slowly.

Oh is it winter 2021/22 already?

The member 'Weather-History' might be able to help you with more accurate details than my anecdotal waffle. Maybe TWS will recall it, although I don't think he was in an area that experienced much of the impact?

If I recall correctly that it was a decaying cold front from the north that somehow developed a low pressure system along its line as it moved slowly south and as it hit the south coast it started circulating moisture from the Channel back northwards into the flow so it kept it going from around 4pm throughout most of the night. We were in an almost unprecedented red warning zone 24-48 hours beforehand (I thought it had to be some sort of error) and was the heaviest fall/accumulation of snow we had here this century.

It doesn't seem to be decaying much, given the increase in size and intensity throughout the day so far?

Does anyone know why nominally the same NE airflow causes the shower pattern to appear so different over East Anglia and the South-East (larger smudges of light/medium-intensity precipitation) whereas The Wash northwards it is a more typical shower pattern with many small blobs of medium/high-intensity?

Yes, the weather type is snow, but look at the %'s - below 20% for the most part and when it's at 41% the symbol is dry. Some people must be so confused and yet they are always hyping this service up on TV trailers.

In a bizarre reversal of Abingdon fortunes when it comes to snow showers, I have ended up under practically the only moderate-heavy radar echo in the entire region. In spite of horizontal nature of the snow it seems to be providing a covering at -0.4C.