And #259 

https://www.wetterzentrale.de/maps/GFSPARAEU12_336_1.png 

 

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Interesting 18z

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18Z continues the theme of the 12Z with the early break up of the Siberian high

Into the East siberian high and the sciberian high. Its far from ideal. That cold air (black in W siberia) is not getting close, and we are getting the crumbs.

We need the siberian high to be further east and stronger for longer.

Quite dissapointing in terms of getting cold air into Europe.

Although it is nice to see such an easy linkup with the heights to the south, but tbh I assumed that would fall into place anyway.

 

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Just wanted to say thank you a very entertaining evening and for all your posts. The explanations are helpful and I am understanding the game of consequences a lot better now. I was convinced we would see a decent Scandi high by the 9th, and anything more by way of link up to the Siberian high - would have delivered something for the history books, and would have provided plenty of fodder for the likes of Ian Curry, - The Great March Snow Storm - and after record spring heat - as for being ‘too late,’  I remember 4” of snow in London on April 12th 1977, after a day of massive convective soft hail sowers. However, a true beast would beat that.... It has kept me closely watching the models since the last - for me - memorable cold spell (17 cm and ice days, ice thick enough to walk on and an ice palace from road spray), and something noteworthy for the memory and history books, (other than Covid that is)!

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There's always hope, though despite Q's painstaking work I remain unconvinced by any LRF techniques - that's what makes weather so fascinating. Meanwhile for you and other southerners to salivate over

This is not the first time Surrey has seen snow so late in the year, with April 25 1950 seeing a foot of the white stuff on Box Hill, despite temperatures hitting 21C at the start of the month. Snow also fell heavily on April 27 1919, six to nine inches settled over April 25 and 26 in 1908 and “massive, deep snow” lay on the ground on April 25 1981.

https://www.getsurrey.co.uk/news/surrey-news/sometimes-snows-april-how-flurries-11250721 (incl photo)

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FAX - even though there's a well -established HP 1040mb by Friday there are trailing fronts around so cloudy at times for some areas.

GFS - current SW-lies pushed out of the way by HP as in FAX, most intense and centralised over UK Sun 28th. The HP then sticks around, moving first to the E, then re-establishing from SW and (after a slight weakening Fri 5th) forming a ridge to the Baltic - but never far away.

GEFS - temp dips Fri 26th but otherwise good agreement on dry (noted that W Scotland  has a day of heavy rain to start with) and mild through to Fri 5th, and not bad agreement on dry and seasonal norm after that though a few runs show more rain at the end esp in NW, i.e. around Wed 10th  

ECM - similar to GFS at first, though weakness shows up a day earlier i.e. Thu 5th and the HP then moves N-ward with link to N Norway and (on the last chart Fri 6th) a hint of a developing easterly

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The difference between the 6Z GFS and GFSP is all down to that canadian cold pool.

Look at the GFS at around 192hours. The -40C isotherm is gone and its higher than -30C. All that cold air was dumped into the atlantic and spun up a huge LP that killed off the siberian high.

Then look at the GFSP, the canadian cold pool is still in tact and so is the siberian high.

 

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Seems like spring is starting to take hold in the charts, but I wouldnt rule out a sly quick shot easterly and snow.

Im seeing a lot of synoptics that remind me of March 2006where western areas got a stalled front and alot of snow. Was short lived, but was fun.

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The most frustrating snow event of my life. The front stalled just touching the Sefton/Lancashire coast. We got light snow on and off for hours, but only perhaps 1-2cm.

Two friends of hours had taken their caravan to near Windemere and woke to the snow level with the bottom of their door (approx 18"). Their dog ran out... and disappeared into the snow. They had to leave their caravan and go collect it a week later.

A Mate of mine lived in Dunblane and again had around 18" of snow.

If the front would have got another 20 miles eastwards, we'd have had a great snowfall. Did Wirral manage to get a dumping?

 

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This was the last decent snow event for this area.  Weve not had snow like it since.

 

The snow drifted really bad too, my car had no snow on the top, but 1-2ft over the bonnet and to the ground.

 

I think level snow was about 13cm - alot of the volume in the photo was from what blew off the top of the house

 

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We actually had a decent overnight fall the previous weekend. The preceding fortnight had seen a straight northerly and North Wales got plastered (I remember Bren posting some amazing pics round his parents' place). But that weekend before your snow, a streamer set up off the Irish Sea and aligned right for us. I've still got a radar screengrab somewhere. Was only about 3", but it was the first decent snow since my first daughter had been born and we spent the morning towing her round the garden on the sledge and building a snowman.

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Why is the 12Z so different. Canadian cold pool. This time its more intact, less of the energy going into that trough.

Siberian high in roughly the right place but extremely weak and shallow.

 

 

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Broadly the same idea on the GFSP

Its a shame about that trough, unfortunately its pretty baked in now as a consequence of that cold pool being too close. The good thing is that once it clears we still have a shot at this.

 

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The 12Z is genuinelly good. Best in ages actually.

Siberian high in the right place, not too much interference from Canada (though unfortunately there is some), and the Siberian high stays intact long enough to not cut off that very cold air. I'd expect this one to end very cold.

GFSP a little less good due to more interference from Canada.

 

 

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In space, no one can hear you scream

I would love another cold shot!

ALL IN FI range but amazing levels of blocking over Greenland what's this 1095mb?

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Jetstream forecast is for the current line of flow to weaken and then for a new jet to resume well to the N of the UK until Fri 5th after which a broad jet reappears over the S half of the UK or at times over France to Fri 12th.

GFS - current SW-lies pump up HP over UK for a more limited time than shown yesterday (to Wed 3rd) after which it sinks S-wards and W-lies dominate. On Sun 7th a secondary LP runs across S England and deepens in N Sea with cold NW-lies following and then takes another bite Tue 9th (975mb Cornwall). The system drifts off to the E with weak N-ly flow Fri 12th. All concordant with the Jet forecast but not much resemblance to yesterday's GFS, nor any hint of an E-ly pattern setting in.

GEFS - hasn't really caught up with the op chart above, still showing mild and dry to Sat 6th with good agreement, then more variation between runs but then still mostly around seasonal norm (a little cooler in N) and occasional  rain (more in W)

ECM - hangs on to the HP for longer and extends ridge to Norway Sat 6th. No sign of a W-ly spell or any secondary LP developing on the Atlantic

 

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... I wondered why it was so quiet in here...

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DEW's good summary is where I normally go to first each day.

I'm pleased that HP looks to dominate and with it some pleasant days with a risk of overnight frost.

What's not to like (especially as I have a load of outside jobs to do)