Model Output Discussion - Spring Has Sprung

[WYorksWeather]

Not a great chart for Easter this on the ECM 12z. Unfortunately, it does seem like those very long range FI charts from the GFS were pretty close to the right idea.

I will wait for the ensembles to see if there is any sign of an improvement in prospects as we head into April.

[Mcconnor8]

The pun run going for the cold northerly at day 9 post Easter.

[ANYWEATHER]

 feb1991blizzard how I hate that term or phrase ….WOWSERS AWFUL JUST AWFUL

[Jordan S]

On 18/03/2024 at 11:38, Jordan S said:

The latter frames of the models recently are typical of the extensive northern blocking that is set to build and dominate further, with any brief spells of drier weather most likely in the north/northwest during Easter and indeed early April as said previously, though unsettled is the main theme for the UK as a whole, cool for the time of year out of lengthy sunshine in the north with wintry showers a continued possibility but quite typical for the time of year, very unsettled conditions still more likely to move in from our south/southwest over Easter and beyond for southern and western parts in particular, only a remote chance of any snow here, just potentially again very wet with slow moving fronts, northeast/easterly winds especially in the north a high likelihood, more variable/southwest/southeasterly for the southern part of England, potentially some thunderstorms in the far south.

Models are in good agreement over the deep low and the positioning just to our west and that's been the case for days.

Anyway..

The outlook quoted above from mine from the 18th and indeed the other updates I've done recently is largely very much still accurate in regards to the general synoptics and weather conditions expected for Easter and then through first week of April.. most unsettled central/southern England with generally drier and slightly colder conditions in the northwest in early April with wintry precipitation with high to our northwest, that is still most likely and that's been a theme in my post updates from the 15th March! although could be some longer spells of  rain/snow for Scotland depending on how far north frontal boundaries reach at times, wind direction largely expected to be as my previous posts have mentioned, more northeasterly in north for a time and more variable in south with thunderstorm risk and very wet weather distinctly possible at times here with only very low risk of wintry precipitation on high ground in central/southern UK.

In terms of Easter day itself it may actually be mostly dry in some areas with sunny spells bar some heavy showers and areas of cloud in some areas, wintry precipitation in parts of the north.

Again an increased chance of drier conditions more widely through second week of April courtesy of higher pressure to our west/northwest moving in, but model output itself for this evolution and signal is rather weak at the moment.

So as for confidence of said outcomes..

Confidence rating of a colder and less wet transition in north/northwest and unsettled first week to April overall for many further south, especially in south with temperatures around average/slightly below here 90%

Confidence rating of a lengthier drier spell for the UK as a whole through second week of April courtesy of those heights to our northwest well advertised by me in previous updates, with temperatures around average at least at first? 60%

Around mid April 13-15th and their are hints we could see a synoptic pattern evolve that results in our first generally very warm spell over England and Wales accompanying a lingering possible drier spell in the south, with a south/southeast wind, this quite typical of how blocking highs can align themselves after a colder spell but any particularly warm spell unlikely to last beyond a few days before either wetter, cooler and windier conditions may move back into southern or western UK or colder air is filtered within an anticyclonic drier pattern over the UK.

In fact by then so around and even after mid April a more traditional synoptic pressure pattern for the UK may try to finally take full control over the UK building heights to our south with the Jetstream returning to the usual northerly positioning with variable conditions day to day in north, wettest northwest/drier south but too far out for any more detail on that. 

A lower chance that southerly tracking lows continue right through the second week to mid April and beyond, continuing the wetter than average theme for southern UK in particular and continuing the exceptionally persistent pattern that has effected the UK since July last year for the most part, worrying if that where the case and would raise questions as to just what this could mean for the rest of Spring, especially as I don't expect the wet weather to continue all the way to mid April and beyond, but the first week of April definitely likely which is problematic in itself, again especially in southern UK at times, but for those wanting late season snowfalls then there is interest in that regard further north if the lesser likely outcome further into April materializes, as well as the expected wintry precipitation at times in north early April mostly in form of showers/ especially high ground.

Take care all.

[Rain All Night]

10 hours ago, Rain All Night said:

0z/6z deterministic runs, out to Sun 31st (day 7)

0z/6z ensemble means, out to Mon 8th (day 15)

Everyone sees colder and perhaps drier weather after Easter, but views are starting to differ beyond that.

12z/18z deterministic runs, out to Sun 31st (day 7)

Ahh it's nice to see these later frames showing weather that isn't coming from the west for a change!

12z/18z ensemble means, out to Mon 8th (day 15)

GEFS still seems less willing to buy into the colder scenarios favoured by ECM and GEM.

[Cheshire Freeze]

The 18z GFS is shockingly wet.

Quite cold into April too with a snow threat

 

[Penrith Snow]

Models have trended even worse overnight, firstly the Fax Charts have Thursday low centred over Western Scotland compared to Western Ireland yesterday so this has the effect of the low stalling and filling over the UK during Easter instead of out West which would have given us a more southerly flow.

So Easter is almost certainly going to be cool and very showery with limited sunshine.

After Easter all models now build pressure strongly to the NW so after waiting since Christmas we finally get the Northern Blocking we have been looking for but of course its 8 weeks late. At least the northerly winds shown again on GFS would be drier and brighter but temperatures would be well below normal.

Which ever way you look at it Spring is further away than ever, the repeated SSWs have finally had an effect but not the one we wanted.

Andy

[Anthony Burden]

Morning all,ECM GFS firming up on northern blocking 216/240 hrs good way off into fantasy island but a lot of consistency so a fairly reasonable chance of cold wintery weather in spring after a wet looking Easter,all in all grim.

[Penrith Snow]

 Cheshire Freeze Wow, look at all that rain in Iberia, the semi permanent Iberian ridge has finally collapsed.

Good for the severe drought in Spain and Portugal but the excessive rain in the UK is the last thing we need.

Note the lack of precipitation over the Pole, clear signal for extensive Northern blocking.

Andy

[simshady]

I think we'll be lucky if we see any snow. Who knows? But model firming up on a bit of colder weather, hopefully. Lovely.

[ANYWEATHER]

Looks like the so called expansion of the Hadley Cell, has been decommissioned,  terrible weather for those into southern Europe and indeed parts of North Africa.....expanding Hadley Cell ,my Axxe

[MJB]

GFS 0Z

Winter arrives lol 

[Penrith Snow]

 ANYWEATHER Hmmm, I suspect the collapse of the Iberian ridge is temporary, pressure will be building over the Med soon anyway as the sun moves northwards and I suspect the ridge will be slow to recede come Autumn, I would not be surprised to see a Iberian High dominated winter in 2025

Andy

[ANYWEATHER]

 Penrith Snow probably won’t happen. 

[Rain All Night]

9 hours ago, Rain All Night said:

12z/18z deterministic runs, out to Sun 31st (day 7)

Ahh it's nice to see these later frames showing weather that isn't coming from the west for a change!

12z/18z ensemble means, out to Mon 8th (day 15)

GEFS still seems less willing to buy into the colder scenarios favoured by ECM and GEM.

0z deterministic runs, out to Mon 1st (day 7)

0z ensemble means, out to Tue 9th (day 15)

GEFS is slightly more inclined to follow ECM's lead this morning, though it still offers less strength and longevity to the block. All three models lose the block by the start of the second week of April.

[Stabilo19]

 Penrith Snow

I'm nitpicking but I don't think we can directly say that any upcoming northern blocking events were caused by the SSWs of the past winter. Northern blocking becomes more common at this time of year as i'm sure we all know. 

[ANYWEATHER]

7 hours ago, Penrith Snow said:

Note the lack of precipitation over the Pole, clear signal for extensive Northern blocking.

Andy

Nothing unusual about lack of precipitation over the North Pole. It's not called a Cold Desert  for nothing!

[Daniel_c150311]

I don't know what forum to put this on but is anyone experiencing issues with the charts and live weather?? it wont work for me.

[Benny123]

 Penrith Snow that block would've been nice two or three months ago, but we're always on the wrong side of luck it would seem. 

[raz.org.rain]

 Stabilo19 in more positive news, such strat developments at this time of year are more favourable to a warmer and drier summer.

Edited March 25 by raz.org.rain

[Bats32]

There's no escape on the ECM 12z, deep low still over the UK next Monday. Dire.....PS you can see what I've been searching from the ad lol.

Edited March 25 by Bats32

[stodge]

Evening all

An uninspiring lead in to Easter weekend with the invigorated trough forming a deep LP for the time of year (960 MB or lower) over Ireland. The LP wander sround the British Isles over the weekend before most modesl disrupt it south early next week.

GFS OP was on its own last night and is so again this evening keeping enough energy in the Atlantic to develop further LP in an evolution reminiscent of a west-based negative NAO.

The 12Z GFS and GEM OP runs continue to pursue very different evolutions even at T+180.

The rainfall numbers continue to suggest southern and western Britain will bear the brunt of the weekend deluges.

[CoventryWeather]

Depressing output, perhaps a change later in the mid range on the GFS, but still unsettled. 

The latest ECM Hov-moller showing a change towards week 2 of April, but no sign of drier weather on the ECM longer range. 

Probably be off model watching for the next few days. 

[WYorksWeather]

Possibly the one good thing that can be said about current modelling is that there is something of a signal for something slightly milder (I hesitate to say warmer unless we get temperatures into the high teens widely) and drier as we go further into April. But as with the last attempted dry spell which was supposed to happen around now - the signal is fairly weak. We need to see it strengthen substantially in the days ahead for me to have any confidence in it.

[Rain All Night]

10 hours ago, Rain All Night said:

0z deterministic runs, out to Mon 1st (day 7)

0z ensemble means, out to Tue 9th (day 15)

GEFS is slightly more inclined to follow ECM's lead this morning, though it still offers less strength and longevity to the block. All three models lose the block by the start of the second week of April.

12z deterministic runs, out to Mon 1st (day 7)

A dry continental flow is not looking like the likely outcome for much of the country.

12z ensemble means, out to Tue 9th (day 15)

The upcoming block seems to have a shelf life of about a week, and it seems that there is potential for it to fail to bring us much in the way of dry weather during its tenure.