Even for Kent, the record in April is 510dam. That won't have happened for many a year!

One day after posting that...

(A few hours earlier than Brian's chart - and as he says, bound to be one of the coldest members, if not an outlier).

Insane GFS12z. Obviously will be an outlier.

 

Not necessarily. Keep in mind on the 0Z we had a -23.5C T850!

The all time minimax record should be fairly easy to beat given the right conditions. All we need is a shortwave moving into that cold airmass with an all day snow event. Should easily smash the -1.1C record.

The minimin record will be somewhat harder, need slacker winds for that.

Obviously nothing will ever compare to that P12 0Z ensemble. But one of the 12Z ensembles (I haven't worked out which) still manages to get the -18C line across the UK which is still insane (and 3C colder than the GFS OP)

Obviously nothing will ever compare to that P12 0Z ensemble. But one of the 12Z ensembles (I haven't worked out which) still manages to get the -18C line across the UK which is still insane (and 3C colder than the GFS OP)

8 gets to -17C - close but no cigar.

https://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&mode=1&code=8

The young (even the relatively young) and excitable here wont remember Aprils of the past. 

ECM gonna be fairly direct hit.

That cold front could be really intense. 5C temp drop in less than an hour?

 

The young (even the relatively young) and excitable here wont remember Aprils of the past. I remember several which delivered heavy snow and hard frost, notably the amazing blizzard of late April 1981. More recently April has been a good deal more benign.

It's far too early to call a record cold northerly based on t144+.

I'm 33 & more than happy to leave those Aprils in the past where they belong. The last thing I want to see is ice days in April! 

Forget the April record, the 18Z has a thickness of under 504dm for Shetland.

That can't be far off the all time record.

We are getting to the reliable timeframe now and these charts are rock solid consistent so far.

Still time for things to go wrong, but a historic April cold spell is definitely possible now and may soon be probable.

The most extreme 18Z ensemble is slightly colder than the most extreme 12Z ensemble. So far at 156 we are at about -19C.

Nowhere near the bonkers 0Z P12 ensemble yet. But to be consistently churning out sub -15C ensembles. Insane!

Oh god. -22C ensemble at the Faeros by 162h with -24C knocking on the door!

HOLY MOTHER OF JESUS.

ONE ENSEMBLE HAS -24C ON THE SHETLAND ISLES WITH -26C KNOCKING AT THE DOOR.

FOUND IT.

IN ALL THAT'S HOLY WHAT THE S1HT IS THIS?!

And this isn't even the only one with sub -20Cs to the UK.

Pertubation 29 probably deserves a mention for being one of the most extreme charts I would ever have seen (until this week).

But the fact this isn't even the coldest one says it all.

For the extreme northern tip of Shetland P1 hits -24.5C at 171hours.

If we had 1 hour data I reckon there would be sometime where -25C was breached on this ensemble. 171 is definitely past peak and 168 is prior.

For those that think I'm being Shetland-centric. Coldest ensemble for a bunch of locations.

London: -17.4C

Birmingham -17.7C

Norwhich: -19.0C

Newcastle: -18.6C

Glasgow: -16.7C

Edinburough: -17.6C

Aberdeen: -21.7C

Stornoway: -19.8C

Shetland: -24.5C

Most of these locations have at least 3 separate ensembles getting below -15C, the Scottish ones more than that.

To be honest I'm pretty sure the ensemble average wouldn't be far off the all time coldest April T850 while the upper quartile would definitely be there. The coldest ensemble smashes the all time (January) record ofc.

 

London: -17.4C

 

What would this produce at the surface?

About +5 degrees in the sunshine?

After what has been very benign weather through March, when I wouldn’t have been too surprised to see a cold plunge, and there have been notable snowy episodes in past Marches, we now seem to be getting tantalisingly close to something truly remarkable for April. The way the cold plunge piles down from the Arctic like an express train looks like the east-west jet stream has just tuned 90 degrees and is now north to south. It hasn’t of course, but the cold keeps tumbling...and not much sign of a sustained warm up from the extended charts. 

Is this to be a year without a summer like 1888? Too early to call that, but whilst sunny days will make ice-days difficult, an overcast day and snow fall could be - with those uppers. 

1886 (I think) - 1ft of level snow on Newmarket high street, but GW would suggest such things were.no more, but I guess the right Synoptics - it is still possible. 

Anyone know what is pushing the southerly plunge from the Arctic? 

So much for my bedding plants - just planted out...I would add cloches, but at that level of cold, I think they’ll be little icicles.