Model Output Discussion - Spring Has Sprung

[stodge]

Evening all

The HP is ambling across the Atlantic to take up brief residence over the British Isles but it quickly recedes back north west allowing the Scandinavian trough to take control next week. GFS 12Z OP develops a shallow area of LP over western Denmark next Wednesday which extends west to the British Isles - unsettled but no deluges.

By the end of next week, this trough has engaged with residual energy over the Atlantic to form a broad but shallow trough over much of northern Europe.

Heights remain low over much of the Mediterranean basin and high over Greenland and mid-Atlantic.

Overall, in truth, nothing too exciting one way or the other - it's not untypical late April fare in all honesty. Perhaps a short warmer period over Ireland and the far west of Scotland but the main issue might be the nightime minima which suggest plenty of ground frost for sheltered rural areas with all the attendant risks for horticulture at this time of the year.

[virtualsphere]

I've been looking at Aprils following some previous very strong El Nino events* and what's quite striking is the strong trough anomaly over the UK, which mirrors what we've seen recently, and the setup also looks similar to the charts @Cambrian has posted above for 10 days time with the high over Greenland and into the Altantic:

Rolling this forward to the summer and we get the high to the west of us - which is also something we've seen a bit of this week and in some of the models recently.  If you look at the summers individually this masks a range of options and if the trough is closer to the UK it could be wetter, but if something like this was to verify it wouldn't be a bad summer for those of us in the west as long as the high stays close enough to the UK to be enough of an influence.   It might not be as hot as some recent years though.

*looking at this 2023-24 has actually been classified as "strong" rather than very strong which these charts are based on, though: https://ggweather.com/enso/oni.htm

 

El Niño and La Niña Years and Intensities

GGWEATHER.COM

 

[damianslaw]

Certainly the outlook is very different fayre to what we've experienced for quite some time. Can't recall the last time we had a cold euro trough and strong heights to our NW linking into the pole. We've seen alot of troughing over and to the SW of UK but not to our east and south east. 

If any time of year is most likely to produce such synoptics its now, complete opposite to the south west airstream, instead we have a NE flow.

Short term, a pleasant spell for far west parts, with dry sunny conditions and respectable temps, further east, cool cloudy with showery dank weather.

Next week could well turn quite unsettled for many as lower heights push east , cloud, rain and supressed temps, not what many I expect are wanting. 

Edited April 18 by damianslaw

[Spectromat]

The Met Office this week talked about the development of a 5 wave scenario that could develop and may be long lasting into summer, can anyone discuss what this would mean for weather in the UK especially if the High pressure systems set up to our West please?

[Mike Poole]

 Spectromat Sounds like an early call of a stuck summer pattern.  5-wave patterns can be stubborn to shift in summer, and just need to be wary here of us getting stuck in a trough if the high pressure is too far to the west when the music stops, as it were!

The models are currently very keen now for the high pressure over the next week to move west towards the end of the month.

Nothing warm in the outlook whatsoever at the moment, a welcome break from the rain over the next week or so, but it could all head wrong again after that.  Ho hum!

Edited April 18 by Mike Poole

[raz.org.rain]

 Spectromat I had to look it up and there's a whole lot of references to summer 2022.

[Spectromat]

 Mike Poole Thank you, thought that was probably the case,  It does seem like we are moving away from more predictable scenarios currently.

 

 raz.org.rain Thank you, I will take a look into 2022.

 

[Blessed Weather]

 Spectromat Below is a link to a Met Office blog about the heatwaves of summer of 2022 and the role of the wavenumber 5 pattern.

https://blog.metoffice.gov.uk/2022/07/19/summer-2022-a-historic-season-for-northern-hemisphere-heatwaves/

 

[Addicks Fan 1981]

 Mike Poole you would think with the strong polar vortex that the weather would be better, obviously not and i think we have had a major fallout with our SSW that ended earlier this month.   

It'll be to do with the zonal winds I reckon from this day forward on whatever the weather does.    

[ANYWEATHER]

Northern blocking ,isn't going to fade anytime soon according to the 00z gfs even into the start of May! Looks like Iberia and North Africa are going to take the brunt of heavy cold rains and very surpressed temperatures.  In fact of talking record highs for Iberia ,we could be talking of record lows of temperatures and rainfall  for the time of year.......  Although !I hate the term "records "as it's all happened before ,long before man started noting weather data...☺

Edited April 19 by ANYWEATHER

[jamesthemonkeh]

ECM seems to have switched to low pressure close to our south-west for next weekend and possibly a warmer flow.  But I can easily see how this ends up in an easterly flow for early May.  Not a joyful prospect here in London!

[LetItSnow!]

 jamesthemonkeh Dare I say that looks a tad unstable, showery at least, with strong April sunshine and slack pressure. Could be a few rumbles with that.

[CoventryWeather]

Always the day 10 ECM charts!! 

At least the clusters and itself are being consistent last few days with that pattern. 

[Scorcher]

 LetItSnow! Exactly what isn't needed after the 6 month monsoon season we've just had and a stupidly high water table.

[minus10]

Remarkable level of similarity between Gefs, Eps and Geps 0z for 850s..

...reasonable level of certainty i think for the remainder of April then the trending back to average temps (or even above ) for beginning of May..not completely dry although hopefully less rain than what we have been encountering...

[jamesthemonkeh]

 LetItSnow! Yeah I think the set-up for next weekend could be tasty, more bothered about the dull and cool that could follow, at least for the eastern half.  Long way away though.

[Sherry]

Gfs ensembles do show more average temps maybe a bit above and tbh heading into may thats not a bad temp to be at looking at 16/17 in the south! Any sunshine should feel nice! But does also show unsettled with rain spikes 

[Rain All Night]

On 18/04/2024 at 12:31, Rain All Night said:

0z deterministic runs, out to Thu 25 Apr (day 7)

GFS persists with its mini-beast.

0z ensemble means, out to Fri 3 May (day 15)

GEFS shows something mildly threatening in the Atlantic right out at the end of week 2, but ECM does not.

GEFS also seems to want the eastern trough in the nearer timeframe to cause us more misery than ECM does.

0z deterministic runs, out to Fri 26 Apr (day 7)

...oh, balls. How very disappointing...

0z ensemble means, out to Sat 4 May (day 15)

That miserable trough from the east looks like it's going to move west and attack us head-on in the latter part of next week. It's not then clear whether the Azores high will be in a position to spare us from the trough subsequently establishing itself on the Atlantic side. That's how I'm seeing it, anyway.

Edited April 19 by Rain All Night

[Scorcher]

Good to see the ensembles trending towards something warmer. There has been a gradual trend towards less cool air next week as well.

Ultimately though we need a dry couple of weeks now- regardless of the temperatures.

[Sherry]

 Scorcher it don’t look particularly dry tbh, the only good thing would be with it being warmer and the sun stronger it should help evaporate some of it so things should dry out easier and quicker 

[Scorcher]

 Sherry Not completely dry no- but next week is looking drier for this area at least- as this week that was supposed to be dry- has actually turned out rather wet.

[stodge]

Evening all

After a weekend of chilly HP for the south and east (much more pleasant further north and west), the downhill path next week looks pretty well set.

The HP withdraws west into mid-Atlantic as a new trough sinks south into the North Sea creating a new shallow area of LP likely to bring some rain and cool conditions especially to eastern coastal areas. Later next week, that trough phases with the Atlantic trough to create a broad but still fairly shallow trough covering most of north western Europe including the British Isles. 

This spawns small areas of LP which consolidate into a more significant feature over the British Isles next weekend.

The rainfall totals based on 12Z GFS OP look uninspiring - at least 30-50 mm over large parts of eastern England and into central southern England so a long way from dry and settled.

It's possible the LP over the south later on will bring in air from a warmer source so a change of something a little warmer though in the more immediate, as I mentioned last evening, the risk of ground frost remains high especially over rural and sheltered areas.

[Sherry]

Looks like a return to the usual Atlantic driven rain fronts again later next week, but does look to warm up! So warm rain rather than cold rain! 

[Cambrian]

Keeping abreast of the models, here’s a notable pair of ECM means, in near perfect hemispheric symmetry around day 9 / 10, persistent heights reinforcing the cleavage.

  

The sheer indecision of it all - sure to be amongst the abiding mam…oops, memories of spring 2024. 

[Midlands Ice Age]

 Cambrian

I agree, a rather fascinating worldwide NH atmospheric pattern there!.

MIA