londonblizzard

UKV 0z updated now. For sunday morning a little bit tamer and precip further south-east than the 21z - surprisingly good for kent and sussex and not too great for home counties north of london.

Hi Nick, at what time do the 00z become viewable on NW extra?

Hi Nick, What chances do you think there are of a south western correction from what the models are currently showing? I'm guessing this would bring the heavier precip region for Norfolk more towards London?

Some exceptional accumulations over holland expected on the eastern flank of the same area of precipitation: Would take one hell of a direct shift west for london to get anything like 40cm though, so incredibly unlikely. Edit: Take those accumulations with a pinch of salt haha

Latest GFS run has the 'rain to snow event' start falling as snow at about sunday midnight (overnight saturday going in to sunday), and by 4 in the morning temperatures at or below freezing covering this entire area. Then from this point onwards temperatures don't get above freezing until thursday or friday. I think the GFS can often exaggerate a little bit the cold of surface temperatures though.

GFS op not without GEFS support and doing what a cluster of perturbations has been doing for a number of runs now. Just incredible the amount of scatter still there for southern england, a 9.5°C range at T60. Probably represents both the fine margins involved in regards to the position of the low as well as the GFS's inability to handle it.

Yes ofcourse, 3 straight days with a -9 to -10 uppers mean seems great to me for this part of the country, especially when we have been teased with milder sectors on various runs for a number of days now. I accept that later on in the chart is a bit disappointing for people after longevity

That's an outstanding london mean!

Netherlands is going to get hammered, but theres a pretty defined southern limit to the cold across europe for this cold spell. Luckily the english south coast just about stays in that limit, at least until midweek

Anyone else quite enjoying the fact that this will be a cold spell *not* affecting france and central western europe? Always get a bit envious when we have a easterly cold spell here and it just looks even colder with our neighbours on the continent, like in 2018

Absolutely no issues with rain from sunday onwards on the ECM 12z, even in the extreme extreme extreme south east

Yesterday's ECM 12Z introduced a big milder sector for the south east on monday. None of that today! At worst -8 clips the kent coast:

-9 uppers widespread by sunday lunchtime on ECM 12z z

Zero marginality issues from the ECM for monday

Yes i think this is possible. Check out the UKMO for wednesday, pretty south:

Short 0Z GFS london ensembles until wedneday: The op milder than the average for sunday to tuesday. Similar to 18z, a good cluster still in -10 to -12 region.

So in terms of having the best combination of heavy snow whilst also keeping very cold uppers for us in SE England, perturbation 14 from GFS 18z is a good example: Brutal -10 to -12 uppers (for the entirety of monday & tuesday) and the western edge of the band of heavy precipitation, expected to cause over 30cm of snow in holland, extending well in to SE England. Many different ways the op runs could shift over the next few days, but theres a few ensembles currently suggesting something similar to this. The servers to this forum are going to crash if the op runs start showing the above.

For london thats the best short ens set in a while! For monday onwards the mean gets as low as -8.9 and a big cluster of members appearing in the -10 to -12 region.

-11 uppers for london and northwards on tuesday!

Between sunday and monday: ECM's coldest day is sunday, UKMO's coldest day is monday.

Already colder uppers further south on ECM 12z compared to 0z on sunday!

Does the 6z and 18z only go up to 72 hours then?

Once the low clears southwards from the UK, if the heights to the north act as a more intense block against the spanish low moving north and following that cause the atlantic lows later in to next week to slide, these special charts are about to get a whole lot more special. Thats a big IF, but strikes me to be within the realm of possibility. Probably the most interesting model watching i've ever taken part in.

Biggest step today back towards cold on the GFS and GEFS suite. I'll take a 6.5 mean for today although londoners and southern coastal regions always need things a little bit colder than other places to rule out slushyness, so hoping it'll start to revert back fully to its -8/ -9 mean seen earlier this week with a more southerly tracked low and stronger easterly.

Wouldn't put that past the GFS.