Model Output Discussion - Spring Has Sprung

[SollyOlly]

 Cambrian Stunning!

[Rain All Night]

22 hours ago, Rain All Night said:

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.

0z deterministic runs, out to Sat 27 Apr (day 7)

I don't think I can provide commentary on these without getting my post moved to the moans thread, so I'm not going to bother

0z ensemble means, out to Sun 5 May (day 15)

ECM offers the most hope of Azores high ridging providing deliverance for at least the south of Britain into early May. The other two models look like they prefer to keep this activity too far west for us to benefit.

Edited April 20 by Rain All Night

[LetItSnow!]

While waiting for the 12z to roll out I couldn't help but notice how much of a big deal the GFS 6z made of low pressure around the 27th/28th. Wet and windy the name of the game here and only rather below average temperatures away from where rain may keep the temperatures down more notably. It does seem weaker pressure of some sort will be the dominating feature of late April, but whether it is slack pressure with showers or a return to notably wet and windy weather, it remains to be seen.

If it does turn like this then April will go down as a thoroughly wet and dull month. Even this drier spell has seen showers on most days here in London. I'm seriously impressed at how long this wet spell has lasted. No drying out round here!

[LetItSnow!]

The 12z of the GFS sees a similar progression albeit in a slightly position. Perhaps a cool, wet and windy end to April on the cards.

[WYorksWeather]

Looks like a trend on GFS for temperatures to return back closer to average by the end of the month after a cooler than average period. Still no sign at this stage of an incoming heatwave.

At the surface, we do see a warming trend through the mid point of the run but it's also accompanied by more rain.

Looks like a bit of a trade off - we get mild but not especially warm weather back, but in return it comes with a greater risk of rain. Fortunately most runs are not excessively wet, though.

[Don]

19 minutes ago, WYorksWeather said:

Looks like a trend on GFS for temperatures to return back closer to average by the end of the month after a cooler than average period.

Yes, the GFS has been showing that for several days now.

[Rain All Night]

I'd love to hear a forecast of surface conditions into next weekend based on the 12z model runs if anyone fancied posting one.

[WYorksWeather]

 Rain All Night I'll make a go of it using GFS and ECM.

Macro scale

The 12z GFS OP at days 6, 7 and 8 (next Fri, Sat and Sun) looks like this:

The ECM looks like this:

Main difference is that the ECM has a much weaker mid-Atlantic ridge further west, allowing more low pressure influence.

UK-specific - GFS

Moving on to the UK-specific view. Starting again with GFS - after a pulse of rain on Thursday evening, Friday looks mostly clear with mainly scattered showers, so hopefully fairly dry for most of us. Still on the chilly side though - maxes barely making it to double figures. Winds fairly light though so may be pleasant at times if there are sunny spells.

Moving onto Saturday, the GFS moves a ton of rain in from the west through the afternoon and evening. Showing the early afternoon chart here but the rain over Ireland has the UK's name on it. Temperatures slightly up on Friday but feel-wise probably worse. Wind direction switching back to south-westerly but quite a strong breeze.

Finally, on Sunday the rain keeps on coming, temperatures struggling especially where the heavy rain is in NW England, temperatures barely even mid-single figures, an utterly vile day by that standpoint for the time of year. Lighter winds for the south but very windy, possibly even stormy for western coasts and especially for Ireland.

UK-specific - ECM

On Friday the ECM keeps it mostly dry early on away from Scotland and the SE, but rain moves in later on, but up from the south. Temperatures in the south barely reach double figures and cooler still elsewhere. Winds are light and from the east.

On Saturday very widespread and heavy rain reaches almost all areas of the UK. The south reaches double figures but it remains cool or even cold further north. Temperatures in the south probably helped somewhat by a change in wind direction to more of a south-easterly, but still not overly warm.

For next Sunday, the ECM doesn't have things quite as wet as Saturday but still a lot of rain around. However it's a far warmer day so if there are any dry spells it will feel warm, possibly even quite humid. Quite a change with a southerly to south-easterly wind, but relatively light so shouldn't take too much off the feel of the warmer temperature.

Summary

In short if it's dry weather you're looking for these charts are an absolute horror show. They're not great for warmth either but the ECM does get us something a bit warmer by Sunday courtesy of more southerly influence.

 

 

[Rain All Night]

 WYorksWeather Thanks. Didn't think it was going to be good news...

I had definitely allowed myself to be fooled into thinking that the loss of the westerly influence meant significantly improved weather for the UK. I won't make that mistake again!

Edited April 20 by Rain All Night

[WYorksWeather]

 Rain All Night Still time for the details to change I think but it does look like the breaking down of our current pattern and the transition to something else will happen next week. It is encouraging that both GFS and ECM in their extended range do eventually get us to something warmer, but in the case of the GFS it is a very long way off and doesn't really happen until a few days into May.

[WYorksWeather]

 Rain All Night Well, I'd describe this current weekend as an improvement - it's been dry and in terms of feel despite being colder temperature-wise it hasn't really felt it here - today has been warm enough to sit out due to the warmth of the sun especially around midday.

Anyway, won't say any more here so as not to derail the thread...

[Kirkcaldy Weather]

I've already discussed that a lower amplitude cycle of the MJO's global progression was going to occur and also a feature linking to El Ninò but I thought this would be a good example which links with my post back in July.

 

A great example again that a low amplitude MJO cycle can still give active weather conditions.

Currently the main part of the MJO is travelling from South America through Africa and into the Indian Ocean. [Credit JMA]

This will enhance what I believe is a CCKW - Convectively Coupled Kelvin Wave from South Africa. As the MJO moves across South Africa and enhances the CCKW this sees significant rainfall and flash flood risks particularly off the coast of Tanzania & Kenya with places such as Zanzibar and Pemba Island prone.

Current timing shows the MJO starting to move across the Maritimes during April week 4 into May week 1. As the CCKW moves Southeastwards the significant rainfall impacts could extend into Madagascar similar to recent weeks.

I've discussed the teleconnective feedback playing into our ongoing 500hpa developments and looking into the MJO composites with recent and ongoing progression of this cycle not surprising seeing high pressure - blocking being a prominent feature again trends continuing into Greenland. The UK trough / Low Pressure can also be noted within these MJO phase feedback. There may be opportunities for some high pressure extending toward the UK and Ireland at times though there isnt any concrete signal for this in current modelling though the 00z GEPS did hint toward the latter part of May week 1.

[ANYWEATHER]

Dartboard low for next weekend? No thanks, but at least at this time range , it has the caveat of being incorrect! ☺

[Penrith Snow]

You can't polish a turd and you can't say this mornings ECM is anything other than miserable. After the next few days of cool, showery weather low pressure takes over to renew the monsoon conditions of March with Southern districts in particular exposed to low pressure to the south west. Meanwhile a large high develops over mainland Europe bringing most of the continent a early heatwave. Let's hope this isn't the pattern for summer.

[ANYWEATHER]

1 hour ago, Penrith Snow said:

. Meanwhile a large high develops over mainland Europe bringing most of the continent a early heatwave. Let's hope this isn't the pattern for summer.

Really can't see what you mean by that ! Looks changeable for southwestern parts in picticular in the next ten days, and even stretching ahead in the silly time frame of gfs, no picticular settled spell for southern Europe.  Anyway ,with northern blocking still persistent and showing up right through the time frames,  can't see any thing too hot for Europe at the moment. The gfs/ecm shows low pressure influencing the uk next weekend,  but the ecm has much more of a flabby low compared to the gfs , hope there both wrong and we don't get a direct hit !

[damianslaw]

 ANYWEATHER If the above synoptics verify I think many will be rating April 2024 as the poorest since 2012. Despite the warmth of the first 2 weeks it was combined with cloud and rain. 2021 though was very cold was also very dry and sunny.

The models are showing no sustained settled spell, by mid week we see a pincer attack - low heights to the NE merging with the atlantic trough to the NW, end product low heights over the UK, cool and wet conditions. Not clear how things may develop as we approach May, generally a very changeable outlook at a time of year which is often associated with not very changeable conditions, settled weather fans have drawn a short straw since June by and large. 

[Addicks Fan 1981]

 damianslaw I think the weather what we are having is stratosphere and upper troposphere related currently and yet we still have a strong polar vortex.   

Think we need to keep our eyes on stratosphere developments, the MJO and to what extent we decline out of el niño, those are the three things to our weather going forward.    

We need views from @MattHon this badly and for him to enlighten us on some potential scenarios.     

[MP-R]

 damianslaw This is very much the time of year for changeable conditions... Highs in funny places, lows coming in from different angles and not following traditional trajectories... not unusual for April & May. By June (latest!) I would expect to see low pressure to have been shoved well north with more high pressure influence.

A long way to go it would seem, although the latter frames of the GFS 06Z making an effort to make high pressure over Europe a bit more influential against a simultaneously stubborn Atlantic!

[Rain All Night]

23 hours ago, Rain All Night said:

0z deterministic runs, out to Sat 27 Apr (day 7)

I don't think I can provide commentary on these without getting my post moved to the moans thread, so I'm not going to bother

0z ensemble means, out to Sun 5 May (day 15)

ECM offers the most hope of Azores high ridging providing deliverance for at least the south of Britain into early May. The other two models look like they prefer to keep this activity too far west for us to benefit.

0z deterministic runs, out to Sun 28 Apr (day 7)

Again going to refrain from any commentary on these runs...

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

It's clear that low pressure will be in control from Wednesday until the end of April.

These ensemble means suggest that some perturbations may be showing pressure rises (surface or upper) over the UK from the beginning of May.

[Addicks Fan 1981]

 Rain All Night i think when we have a zonal winds recovery then things will probably settle down but it will i think be arduous.    

[Sherry]

Amazing gfs 06z run towards the end

[stodge]

Evening all

It's been a chilly but fine weekend here in lowland East London but next week looks to progressively turn more unsettled as the HP recedes first north west and then west into the Atlantic and the Atlantic trough phases energy into the Scandinavian trough and the two set up over north-west Europe.

The problem is the trough becomes wedged between heights over the Atlantic and heights over Eastern Europe and the LPs rotate north to south and south to north crossing and re-crossing the British Isles. The south west looks to catch most of the rain going with nearly two inches in the next ten days while other southern and eastern fare better though I suspect the evolution will also mean sharp showers.  ECM 12Z OP offers the trough sinking into Europe as heights try to build through the north of the British Isles but the common theme is recurrent if not strong northern blocking which, aided by a slack jet doesn't mean significant change (or any change) happening too quickly.

Tentative signs of temperatures recovering early next month but this week features a couple of nights with extensive air frost and ground frost which will be a concern to horticulture at this critical time.

[ANYWEATHER]

Will be surprised if this low pressure system is anywhere near  the uk by the time we get to that timeframe....☺

[CoventryWeather]

 ANYWEATHER the trend today is to have that feature significantly weaker and further west and south. Could be a bit of a plume event on the eastern flank if it came off.

[Addicks Fan 1981]

 CoventryWeather as i've said in another post is we need the zonal winds on our side as @Kirkcaldy Weathermentioned.   If they reverse to positive then we should get something more favourable, in the meantime we need to grin and bear the mundane weather we have.    

I believe what we are having as I've stated above is a tropospheric response to our SSW that started in mid February and ended in the early part of this month.    

Also there is a strong east QBO currently that is trying to reverse into westerly but is struggling as things stand.    Reckon the east QBO is counteracting the strong PV and that's created more of an altercation with the atmosphere.   

Edited April 21 by Addicks Fan 1981