Model Output Discussion - Spring Has Sprung

[Mike Poole]

A good while since I posted in this thread, and the relentless dross continues…

I seem to remember saying, what with the late strat reversal, that it would be the final third of April before anything settled and warm/hot took hold.  It is really difficult to see any improvement before that.  GEFS 12z mean at T300:

Everything is continuing to go the wrong way, with the jet on a NW/SE track (black arrow), nowhere near what we need to see to set us on a summer trajectory (red arrow).  

I remain hopeful that the pattern (with at least some of it related to the stratosphere) will blow itself out by the end of April, two scenarios for you at that point, 1) sudden flip to warm/hot, 2) a slower burner, gradual improvement, which still means most of spring will have been unremittingly rubbish.

My money is still on 1) but there’s no sign of it in the models yet…maybe see it in the outer reaches after another week?

Edited March 30 by Mike Poole

[northwestsnow]

 Mike Poole

Hopefully we will see a settling down as we move through April.

EC 12z looks unsettled out to day 10 .

One can't help but wonder if the Atlantic ssts are to blame  

Regardless chasing winter weather Nov - Feb is fast becoming a complete waste of time in our new climate.. 

[lassie23]

Still waiting for the recent SSW to bring the first snow of the winter here in London

[danm]

2 hours ago, Mike Poole said:

I seem to remember saying, what with the late strat reversal, that it would be the final third of April before anything settled and warm/hot took hold.

A late strat warming is usually the death knell for any early Spring warmth. Southerly tracking lows, northern blocking, lows stuck between areas of high pressure making the UK a trough magnet. It’s why I am always against the idea of having one so late in the season. 

[LetItSnow!]

Something interesting on the latest run of the GFS is how close the 15C line is from us. A slight adjustment could see the UK under some truly very warm air. Interesting that the 15C line is usually associated with the hot spells in the iconic summers of the 20th century so to see that it's flirting with us in early April is a little concerning! Times truly are changing... No doubt this very warm air is fuelling the low pressure due to the temperature differences. April power showers...

[CoventryWeather]

There is weakly a trend in the last few days to show something drier towards mid April, but I can't say I'm keen to see it until it gets into the reliable. 

The ECM 46, CFS and the latest GFS runs slightly heading towards that route - a fairly mixed April to come, a washout for the first and a much drier second half? 

Also be interested to see previous dry May months, as I feel it's an increasing possibility now (see how that unfolds over the next month XD) 

Edited March 30 by CoventryWeather

[Weather-history]

What a poor chart for the first weekend in April, a sub 970mb low passing over the British Isles.  

 

[minus10]

Well happy Easter everyone...hope you have a good Easter Sunday if you can..was hoping for a bit of sun today...but dull and gloom so far..yesterday was a lovely day with some decent sun and nice to see that blue sky again..

..as for the models...sadly no change really in this very unsettled weather pattern with the 'trough sandwich' extending from the west/south west  over the uk at times with consequent run of low pressures moving in to influence our weather...

...even at day 10 the trough still much in existence as per gefs 0z ..

..as a result lot more rain for most for next 10 days at least..

...France, Low countries and particularly north west Spain/Portugal also getting significant rain although notably most of the Med significantly drier..

..although wet it does look as so it will warm up a bit ..

Gefs 2m temp anom for 6th to 11th April showing positive anoms extending from the south over much of the uk..so in any sun it should feel quite warm actually..

..what is also noticeable about the next 10 days or so is the higher levels of certainty for this weather pattern in the ens..

Gefs 0z

Eps

 

...grim really but just got to hope like yesterday that those drier and warmer days become more frequent between the downpours...

..have a good day...

 

Edited March 31 by minus10

[WYorksWeather]

Not looked at it for a while now, so worth a quick check of the North Atlantic SST forecasts again.

Here are the actuals at days 0, 5, 10 and 15, taking us to the 15th April:

You can clearly see the warming trend from the annual minimum starting to kick in now off the Mediterranean coast - those brown colours moving up from the south-west. Still not much impact over the UK at this stage though.

 Here is the same data in anomaly terms:

Our old friend is forecast to return (or enemy, depending on your weather preference). Once again, after the current break, the ECM is forecasting that in a few days, the Azores SST anomaly will return once again.

This may be a useful explanation for why we're seeing some odd patterns, in terms of that cyclonic south-westerlies, which would typically be near average at this time of year, will still be capable of producing above average temperatures well into April. SSTs widely 1-2C above the 1991-2020 average will do that.

[LetItSnow!]

 WYorksWeather And those warm anomalies may fuel further lows if the pattern persists as the natural temperature contrast remains large from the north and the south at this time of year. I feel instability in this region could persist though whether the zonal south-westerlies last all month or whether it may promote a more blocked UK high/Azores low set up later down the line is another question. Perhaps a possibility though. 

[WYorksWeather]

The GFS 06z is now picking up on an idea for something a little bit less unsettled. I hesitate to say settled, as the mean is still struggling to get pressure above 1010mb, let alone 1020mb. But even some slightly more mixed weather would be an improvement on the dross we're getting next week.

Edited March 31 by WYorksWeather

[Rain All Night]

23 hours ago, Rain All Night said:

0z deterministic runs, out to Sat 6th (day 7)

0z ensemble means, out to Sun 14th (day 15)

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

How do we get rid of the Atlantic trough?

Edited March 31 by Rain All Night

[raz.org.rain]

 WYorksWeather looks like a more pronounced "cold blob" anomaly is showing up too, which would be ideal if you want a hotter and drier summer.

[Summer8906]

 Rain All Night Jeez, looks like we are almost certain to have the wettest April on record, the wettest spring on record and unless summer and autumn are dry, quite possibly the wettest year on record.

 

Edited March 31 by Summer8906

[WYorksWeather]

So, can the 12z model runs provide us any hope of an escape from the Atlantic trough?

12z GFS ensemble

Again, the GFS ensemble dangles the carrot of something at least less unsettled by mid-month, similar to the 6z. The consensus still looks milder than average and wet overall, though, and it goes without saying that promises of jam tomorrow keep getting delayed and downgraded. If you'll take that seriously at two weeks' lead time, then I have a bridge to sell you. Of course, all else equal, you'd rather see at least some hint of light at the end of the tunnel, as that means there's at least a chance.

Now, on to the operational run.

12z GFS

The 12z GFS is much the same as its earlier output and as it has been showing for quite some time, a whole barrage of Atlantic lows.

Three lows in the next five days:

Another two in the next five:

 

However, more quietly, a bit of a transition goes on to our south just beyond the current reliable timeframe. Here is the chart at day 9, day 10, and day 11.

The increasing strength of the Azores high pushes the next low further north at day 12.

Unfortunately, we're not out of the woods. A small section of the low breaks off and makes a run eastwards. By day 13, after a brief quieter period, we're back under more unsettled conditions.

And guess where we end. Heights to our north-west, to our south, and well to our east, and we end up with a trough trapped right over the UK.

Accumulated rainfall total to day 10 is absurd. The focus changes from run to run, this time it's more western regions getting hammered, and most of Ireland.

Don't worry if you're feeling left out. By day 16 and the end of the run, everywhere except northern and eastern parts of Scotland, and the far SE of England and East Anglia sees at least 70mm of rain. Some outrageous totals in some western areas - parts of NW Scotland, Wales and N Ireland close to 150mm.

Summary

I think the key is going to be that tropical forcing from the Azores at day 9-11. We really are in potentially dire straits here. A lot of places will struggle to handle the rain forecast for the first 10 days. If we then only get a brief drier spell before another washing machine Atlantic low, we could have a very serious situation when it comes to flooding.

We just have to hope that the GFS is underdoing the tropical forcing, and that Azores high influence will lead to a longer dry period.

 

Edited March 31 by WYorksWeather

[Summer8906]

This must surely be a spell 1963-like in its extremity. To have 10 wet months and 3 absurdly wet months (Feb-April) on top of that is just unprecedented.

I've never known anything like this before.

I just hope it's a long time before we get anything like as extreme as this again, in the same way that 1963 was unusual even for that colder and drier era. If this is the UK's new normal climate, seriously God help us. It could even threaten the viability of much of the UK as habitable land.

Edited March 31 by Summer8906

[In Absence of True Seasons]

 Rain All Night Geo-engineering / weather modification. That's now we get rid of it

Edited March 31 by In Absence of True Seasons

[WYorksWeather]

 Summer8906 You can count December as absurdly wet, it was the 8th wettest UK wide. October as well, which was 6th wettest.

Probably the only thing which has thus far saved us from a severe flooding crisis nationally (of course many places have flooded already) is that the locations seeing the absolute worst (200% of monthly rainfall or higher) have varied. The Midlands and South has borne the brunt of it in February and March, but before that us northerners had a ridiculous amount of rain in October and December, and of course Scotland even worse.

To bring things back to the models, for what it's worth if we look at the ECM up to day 10 and use it to mark the GFS' homework in a sense, it looks slightly better. Up to day 10, it has slightly lower rainfall totals than the GFS for most areas.

ECM for day 10 on the left, GFS on the right. The tropical forcing looks much stronger on the ECM. We can't predict it for certain, but might that ridge on the ECM have enough stopping power to stall the low or force it northwards, if the run continued beyond day 10? It certainly looks a bit sturdier than the GFS' version.

Both runs now picking up on this same pattern, so I would have thought some sort of tropical forcing will happen with the Azores high at about this timeframe. It is just whether it is strong enough to halt the Atlantic for a prolonged period.

The ECM ensemble mean isn't too bad either - it's closer to its own OP solution than the GFS OP solution.

Maybe ECM offering us a way out? But again, I really wouldn't like to get anybody's hopes up of a prolonged dry period until we get a bit closer to the timeframe.

[damianslaw]

I'm not saying 2024 will verify in the same way 1998 did, but there has been an uncanny resemblance to 1997-98 since November. Look away at April 98 it was a low pressure fest from start to finish of a cold variety, but things did break at the start of May.. we had seen a very wet period since June 97 every bit comparable to the last 9 months. big El Nino year as well..  

Big el nino years are synonymous with deep troughs just to our west, 82-83, 97-98, 15-16 good examples.

Edited March 31 by damianslaw

[near northampton]

On 28/03/2024 at 20:36, damianslaw said:

average.

Easter Saturday - less showery, but still threat for anywhere, brighter breaks and will feel mild

Indeed also add

in  3 record Breaking months for warmth, June and September 23 and Feb 23 also smashing the January record this year which was every not a dramatic as July 22, clearly CC,  but models continue to show anomalous rainfalls totals, 

[WYorksWeather]

Deep joy with the 18z GFS. Looks somewhat hopeful for a drier spell around day 11 - that Azores high is a feature on every run starting around day 9.

A couple of days later though, the wheels come off completely, and we have this absolutely lovely chart at day 14.

And just to keep stringing us along, another attempt at building up a high is shown right at the end at day 16.

The worst affected areas keep shifting as you'd expect at this range, but we keep seeing a pattern which is likely to locally deliver 100-150mm of rainfall over the next two weeks, and 50mm almost universally.

Right, that's me done for the night. Chuck this one in the bin and try again I guess.

 

[CoventryWeather]

Is this the beginning of a new trend towards something drier by day 10? 

GFS, ECM, GEM at day 10

Here's the ICON at 180

The ICON would follow the ECM and GEM if it continued to day 10, with the Atlantic trough making a ridge towards southern UK and France. The ECM and GEM are very similar over Europe, the latter not having a shortwave near Denmark, making the ridge look cleaner. 

Certainly question whether the ridge would hold, but a sudden shift overnight.. can it get down to the reliable though? 

Let's hope the models aren't playing an April Fools Joke....

Edited April 1 by CoventryWeather

[Sun Chaser]

 CoventryWeather This ridge is our way out of this spell perhaps! ECM and GEM looking decidedly dry by day 10. First sign of anything other than a zonal trough fest on the models in weeks.

[Penrith Snow]

 damianslaw That's why I didn't expect much from Winter 2023/24 and I always thought forecasts of a cold February were very unlikely given historical comparisons.

Things will change eventually but I worry that increased SSTs to our south west could trap us into a new Blade Runner film type climate.

Let's hope not

Andy

 

[Penrith Snow]

 CoventryWeather Oh God not the dreaded 10 day ECM chart, have been following that since Christmas and it leads to nothing but disappointment.

GFS at day 10 isnt that great either unless you live in a loft conversion in London.

long way to go yet.

Andy