The Enforcer

I wonder how much of the average monthly totals for January has fallen in the first 4 days of the month?

Outside the range of MOGREPS is a little red flag in itself.

GEFS06z P15 is a decent run until 12th when the HP gets pushed south-eastwards: Fortunately, there are plenty of outputs left for that to correct in a more favourable direction.

11 hours of rain yesterday leading to dozens of local road closures and the forecasted sunny day today is filled with cloud.

Please not GEFS18z P29: Cold rain and more flooding.

There's a 2m temperature range of 8C for London on 15th, which illustrates how volatile the situation is at that range: That being said, the highest temperature is only 6C, so certainly couldn't be described as mild.

It was already flooded around here and now we get this: Honestly, this place is such a rain magnet.

You can find them in other posts.

GEFS12z P01 and P10 are two examples of profiles that stop cold weather taking hold beyond Week 1: I would be pleased to see such options removed in forthcoming outputs.

I would probably have more faith in it if it was a median rather than a mean average.

Hard not to when you offer an alternative perspective on the current modelling and a response is to suggest I should go to bed and cheer up. Don't they realise I do all my best work at night?

And so you should quite rightly 'stick to your guns'.

Not required in Phase 1: "Is it cold enough to snow?" but it is required in Phase 2: "Will it snow where I am?" Not as hard as you might think. One day of snow a year please. Hardly ever get it though. I am not highlighting P23 because it is introducing mild air to end the cold spell, it is because it's illustrating an alternative timeline that stops the arctic incursion from reaching the UK. I am perfectly happy thanks for asking.

Yes, but not persuaded otherwise by any of the content. It all comes down to my belief that any options for average conditions should really be weighted by the observer (e.g. one run showing average temps is the equivalent of five anomalously cold/warm ones), given the modelling tends to move away from extremes in favour of more average conditions as T+0 approaches. This means that the mild options would need to be swept from the table to remove the threat. It's nice to be in a position to hope for that, but not likely for a while yet.

Precisely. Only one perturbation converted to mild per run would be sufficient to turn the entire pack mild. And I have seen more sudden changes than that in the past.

GEFS18z P23 not reading the script: and unfortunately it's not the only one. Plenty of time for better, though.

What are GEFS12z P10 and P19 seeing?

From 15th Jan, there's only 50-odd runs to go to reach T+0. What could possibly go wrong?

Fax charts show trapped fronts another wet HP?

GEFS 06z P16 retrogresses the HP, but still manages to go mild: I take some comfort from the range at which this occurs.

Enter GEFS 18z P26:

GEFS 12z P29 is painting an alternative Day 10 picture: Hopefully, this option won't gain traction in the 30 or so runs before Day 5 is reached.

Take a look at GEFS 18z P10.

Have to be wary of the evolution shown by GEFS 18z P10: It would be good to see that knocked out of the park in the forthcoming runs.

As a broad-scale diagnostic tool, clearly it can only take you so far up the garden path. A leap of faith is then required with the micro-scale components to complete the journey. The way this leap is often presented is that it is a simple matter of a puddle that needs skipping over. However, I find that the kind of leap required would be to clear Grand Canyon. If you live in the South-West and Central Southern England region, make that two Grand Canyons.