Model Output Discussion - 15th March onwards

[TwisterGirl81]

1 minute ago, Daniel* said:

Very uninspiring reflected by how quiet it is in here… it looks April will begin much like most of March. Anaemic temperatures and above average rainfall, this is likely the lingering aftermath of late winter SSW at work.

Yes I hope this doesn’t affect us having a good second half of spring and summer, why don’t these happen in winter, not on spring when some of us are sick of the cold!

[Cambrian]

Winds fall light in a gentle northeasterly flow behind the rain next Friday evening, turning chilly as we leave March and enter April on the 12z GFS op. A frost for many parts by morning to begin April. In the event, much more the lamb than the lion.

   

Easy to be “fool”ed by the overall synoptic of successive low pressures…

…and miss the scope for short, calmer, chilly spells in between that can catch us out with unexpected frosts. 

[Rain All Night]

There are heights appearing to the north by next weekend on the det runs, with lows squeezing through underneath:

The ensembles are interested in keeping that theme going into the first week of April, with the GEFS looking more willing to entertain the possibility of stopping the lows going through altogether, I think:

The ECM det run lets a ridge link up with those heights to the north in FI, but in a bit of a miserable position for UK/European warmth, this position thankfully not supported by those ensembles:

Edited March 26, 2023 by RainAllNight

[Penrith Snow]

The GFS is a fantastic run IF it was January with a perfect channel low at day 10.

However, with the season advancing it will be cold rain for most although by day 12 the northerly is potent and snow would be widespread.

All FI of course but at the moment spring is a long way off.

Andy

[WeatherWatchmanG]

Am I missing something but the GFS only on Friday was showing 21c at both 6z and 18z runs but not the 0z and 12z and some Saturday runs still showed this however the latest runs are heading to a colder and snowy period instead.

Two weeks away plenty to play for.

[ANYWEATHER]

Slim pickings from ecm and gfs, to anything settled and really spring like.  A southerly tracking jet stream looks more pronounced than anything this morning. Can someone tell the Weather God's that it's Spring now,! But the remnants of Winter synoptics are still trying to haunt us, hopefully the phantom legacy of winter will soon dissappear!

[mushymanrob]

13 hours ago, Summer8906 said:

Autumnal as in constant southwesterlies, grey skies, mild nights, humid air, low cloud base and non-convective rainfall, which has been the dominant weather type here for the last two weeks.

 

youve described a pretty normal pattern we can get at any time of the year....

[WeatherWatchmanG]

1 minute ago, ANYWEATHER said:

Slim pickings from ecm and gfs, to anything settled and really spring like.  A southerly tracking jet stream looks more pronounced than anything this morning. Can someone tell the Weather God's that it's Spring now,! But the remnants of Winter synoptics are still trying to haunt us, hopefully the phantom legacy of winter will soon dissappear!

Well if snow does come Star Wars Celebration with people coming from around the world will be nightmare for traveling for all sorts of reasons with travel impacts that will cause the event to be a write off.

I want Fridays 6z and 18z runs to make a return those had 21c and only a lowering of temperature on Sunday but still mild.

[Summer8906]

49 minutes ago, mushymanrob said:

youve described a pretty normal pattern we can get at any time of the year....

Perhaps, though a) this month will, assuming the models are correct for this week, end up one of the dullest and wettest Marches on record, so not so typical and b) it is weather stereotypically associated with autumn.

Trying to put a positive spin on the models, both ECM and GFS 00Z at least do veer the wind to a more northerly point (this varies from NW-ly to NE-ly depending on model and day) next week which means at least it won't, presumably, be so dull and the air will be a bit drier. So will at least feel rather more like spring, albeit a colder spell in spring. ECM's take seems to be a changeable but (presumably) brighter NW-ly, while the GFS goes for more pronounced northerlies at times. If those Channel lows can keep where they are or further south, it won't be so bad (occasional periods of cold rain in generally bright Arctic air), but the risk is they move slightly north and that could produce atrocious conditions for the southern UK. Let's hope not.

 

Edited March 26, 2023 by Summer8906

[Rain All Night]

A tentative sign of change has this morning reached day 7, with all the det runs shown below showing disruption in the Atlantic, which ECM 0z and GFS 6z progress into blocking:

The possible blocks that are showing in FI, both believable given the recent ensembles:

GFS 0z ensemble prefers blocking I think (based mainly on the precip anomalies), ECM less sure but looks more comfortable with it by the end of week 2.

Edited March 26, 2023 by RainAllNight

[lassie23]

So sunny 21c with frequent snow showers

[minus10]

1 hour ago, RainAllNight said:

A tentative sign of change has this morning reached day 7, with all the det runs shown below showing disruption in the Atlantic, which ECM 0z and GFS 6z progress into blocking:

The possible blocks that are showing in FI, both believable given the recent ensembles:

GFS 0z ensemble prefers blocking I think (based mainly on the precip anomalies), ECM less sure but looks more comfortable with it by the end of week 2.

Yes....just looking at the pressure mean for gfs 6z and ecm 0z, the mean for gfes in the extended having nothing to do with the op (surprise surprise) and steadily in descent after the initial rise...

...whereas the eps going with a higher and flater pressure mean after the rise..

...the anoms show the gfs with lower than average pressure to the south in the extended..

...while the eps show the lower heights to the west and higher to the east for the same time..

...so my interpretation of that is while both are showing  some form of block the gfs would be cooler and perhaps more unsettled while the ecm milder and maybe more settled..could be wrong though..

Edit...the 6z gfes anoms looks even more unsettled...

 

...sorry about other 2 charts..dont know how they crept in...

Edited March 26, 2023 by minus10
Added chart

[Cambrian]

Lovely here right now after a dreary morning, looking like a good day for one hour longer working in the garden!

6z GFS op brings in a 1035mb+ anticyclone for the UK and Ireland at day 8. The ensemble mean is more ambivalent, but there’s good support for a rise in heights from the southwest ridging north. 

  

The high on the op sticks around for a while too! Temperatures nothing special, the odd brush with relatively shallow lows passing to the north over Iceland, but overall a lot drier and brighter. 

Taken together, the day 8 to 16 animation of the op and the mean anomaly would suggest a much quieter period with a good deal less scope for unsettled weather in the days running up to Good Friday at least. Temperatures nothing special, the odd brush with relatively shallow lows passing to the north over Iceland, but overall a lot drier and brighter. 

 

Hints on the ensemble mean of low pressure working its way in from the Atlantic again during the Easter weekend itself, a stubborn signal on the ECM remaining for that period too, here the encouraging picture of the build in heights at day 8 on the 0z ECM ensemble mean, but not really developing longer term for Easter Sunday at day 14.

  

A long way off, in a slow-moving pattern where the prospects for the UK and Ireland toward Easter currently hang in a balance where just a little more of a shove of heights from the southwest could make all the difference, in allowing the establishment of a firmer ridge or standalone high pressure cell further north, as we see in the 6z GFS op. 

For now, considering the ensemble means, maybe a case of more positive signs of a bird in the hand for the few days from next weekend, and then to keep an eye out this week for some signs that the heights from the southwest can strengthen a bit and in the event be consolidated in a surface high that can hold on a while longer for the long weekend itself. Enjoy the day.

[Rain All Night]

It's interesting to see the wind roses on the ECM parallel ensemble output for the south coast (these meteograms being all we can see at the moment as far as I know) looking more suggestive of interference from high pressure somewhere nearby in week 2 than the current ensemble version (current is left, new is right):

I've noticed that there is now an output from the new daily extended 0z ensemble (aka EC46) on this test site, unfortunately like most of the parallel output it is appearing after quite a long delay at the moment, but nonetheless still an interesting taster:

https://charts-dev.ecmwf.int/products/opencharts_extended_meteogram_esuite?base_time=202303250000&lat=50.7167&lon=-2.0&station_name=Poole

Spotted a couple of other new graphs on this test site that aren't on the live one, one for visibility and another for UV index:

https://charts-dev.ecmwf.int/products/visibility_meteogram?base_time=202303260000&epsgram=visibility_meteogram_public&lat=50.7167&lon=-2.0&station_name=Poole

https://charts-dev.ecmwf.int/products/classical_cams_uvindex?base_time=202303251200&lat=50.7167&lon=-2.0&station_name=Poole

Edited March 26, 2023 by RainAllNight

[Rain All Night]

Four takes on the second half of this coming week. The beginnings of a pattern change in time for Easter, or just another temporary interlude?

Edited March 26, 2023 by RainAllNight

[Mike Poole]

I think we might see a trend towards a more settled second half of spring now, I had pointed to mid April for this and stand by it, possibly a tad earlier.  I always smile slightly at the ‘standard spring fare’ type comments during the first half of spring, because for me, the first half of spring is very much a Jekyll and Hyde period, as it depends to a significant extent on the way the atmosphere was left at the end of winter, vis a vis the stratospheric vortex.  

On the one hand there is the scenario where the strat vortex gradually loses steam, without any shenanigans, towards a benign final warming, this is more likely to bring an early spring in my view.  On the other hand, is a late winter SSW (as this year) or a more explosive final warming (which would be classed as a SSW were it not also the final warming), either way a more amplified meridional pattern may persist for some weeks.  Not that the UK will always be on the cold side of it, but probably will be some of the time, and it is a bit longer before the jet stream can trend to the more northerly track associated with summer.  

Just starting to see evidence now that the SSW has more or less run its course at about 6 weeks.  Zonal winds at 60N from the GFS 12z illustrates:

Two things here, first is the last of the negative wind anomalies seems to drip down into the trop days 5-15.  Secondly, at the top the returned westerly winds are waning towards the final warming.  It is as if the strat vortex has returned to active duty following the SSW, only to find it has a terminal illness due to the inexorable march towards summer, here T6 and T384 shows it now on the way out.

But this should be a benign process from now on, and some warmth should be forthcoming…

Edited March 26, 2023 by Mike Poole

[Sunsetglimmer]

Just now, Mike Poole said:

I think we might see a trend towards a more settled second half of spring now, I had pointed to mid April for this and stand by it, possibly a tad earlier.  I always smile slightly at the ‘standard spring fare’ type comments during the first half of spring, because for me, the first half of spring is very much a Jekyll and Hyde period, as it depends to a significant extent on the way the atmosphere was left at the end of winter, vis a vis the stratospheric vortex.  

On the one hand there is the scenario where the strat vortex gradually loses steam, without any shenanigans, towards a benign final warming, this is more likely to bring an early spring in my view.  On the other hand, is a late winter SSW (as this year) or a more explosive final warming (which would be classed as a SSW were it not also the final warming), either way a more amplified meridional pattern may persist for some weeks.  Not that the UK will always be on the cold side of it, but probably will be some of the time, and it is a bit longer before the jet stream can trend to the more northerly track.  

Just starting to see evidence now that the SSW has more or less run its course at about 6 weeks.  Zonal winds at 60N from the GFS 12z illustrates:

Two things here, first is the last of the negative wind anomalies seems to drip down into the trop days 5-15.  Secondly, at the top the returned westerly winds are waning towards the final warming.  It is as if the strat vortex has returned to active duty following the SSW, only to find it has a terminal illness due to the inexorable march towards summer, here T6 and T384 shows it now on the way out.

But this should be a benign process from now on, and some warmth should be forthcoming…

You explain things brilliantly, thank you, enjoy reading your posts 

[Metwatch]

Keep forgetting ECM hasn't fully come out yet due to British summer time

[Rain All Night]

 

1 hour ago, Sunsetglimmer said:

You explain things brilliantly, thank you, enjoy reading your posts 

Yes he does, I've missed him the last couple of weeks!

 

2 hours ago, RainAllNight said:

Four takes on the second half of this coming week. The beginnings of a pattern change in time for Easter, or just another temporary interlude?

Unfortunately, ECM has taken a "dog's dinner" approach a bit like the UKMO on the left above, and it remains so in the FI frames.

Edit: I notice others below have taken more of a liking to those FI frames!

Edited March 26, 2023 by RainAllNight

[stodge]

52 minutes ago, Metwatch said:

Keep forgetting ECM hasn't fully come out yet due to British summer time

Ah yes, but well worth the wait...

 

Edited March 26, 2023 by stodge

[minus10]

Bit of a chilly easterly from day 8 on ecm 12z..

[Allseasons-Si]

The ECM puts us in the freezer at day ten

Edited March 26, 2023 by Allseasons-si
Added chart

[Rain All Night]

52 minutes ago, Allseasons-si said:

The ECM puts us in the freezer at day ten

Just for fun, a closer look at that T+240h frame, from the ECM website...

Edited March 26, 2023 by RainAllNight

[richie3846]

24 minutes ago, Allseasons-si said:

The ECM puts us in the freezer at day ten

I notice that the GFS doesn't suggest cold for this time period. I suggest the way the ECM hws the cold area  isolated from the north, like it somehow intensifies the cold further south, I rather doubt this will be the case.

[damianslaw]

Not been commenting much on the models recently, as the outlook has painted a rather typical and non-eventful picture, predominantly an unsettled one with the atlantic ruling the roost in the main.

This week will bring a carbon copy of much of the week just gone synoptics, once we clear tomorrow's brief ridge - haven't see much of those features this month, indeed non-existant!, its back to the atlantic long wave trough sat to our west pulling in milder wet and windy conditions to see the month out - helping to tot up the rainfall totals on what will end up a thoroughly very wet and dull March.

As we enter April - a signal for trough disruption, and heights building both to the north and north west and also south and south east - the UK most likely to become the home of the trough which may bring a cyclonic spell, or we might see a continuation of the trough held just to our west becoming slow moving yet again drawing in a mild feed from the south, conversely we might see the opposite with a colder NE feed. Spring is a very tricky season to predict more so as it goes on and the models are often caught out by suddent abrupt changes - low pressure systems doing unusually things, and innocuous ridges and height builds becoming major anticyclones quite often in unusual positions.