Model output discussion 9th April onwards

[summer blizzard]

People appear to be a tad too focussed on the what and not the why.

First the reason the Euro differs from GEM and GFS is simply because it has a better developed upper low near the U.K. so it hangs about a little more instead of shifting like the GFS/GEM.

The key feature that is confusing the models afterwards is an upper trough which becomes cut off west of the Azores at day 5. The initial reaction is that it’s too far west and so we get something of northerly (a strange warm, dull north westerly most likely) however it looks like around day 9 the upper low begins to interact with another low near Greenland. On the Euro this trough moves east and is picking up the upper low, on the GFS/GEM it’s more of a stalling phase which results in some retrogression of the high (though the GFS fails on the first attempt unlike GEM).

Broadly to day 9 the GFS/GEM have the advantage tonight, afterwards who knows.

 

 

[Frosty.]

Probably the last post from moi..got my trumpet ready!  

Anyhoo, tonight’s ECM 12z ensemble mean looks ridgy for the most part, especially later..which would be good news for the majority who prefer summer to be summery..?  

[Mike Poole]

ECM clusters, well 5 scenarios tonight, but all with the red border - Scandinavian blocking.  That’s the main take on this timescale, pick the bones out of this:

It is just a question of when the current low heights over UK drain, and then summer will return, give it a week or so…I can’t see the point in discussing it endlessly, will all be sorted by July in my opinion, with summer charts like in early June. What’s the problem?  

Edited June 19, 2021 by Mike Poole

[Thundery wintry showers]

My reading of the last third of June is "mainly dry but fairly cloudy", with Britain on the north-western flank of the Azores High.  It does depend on the extent of the low pressure system moving in from the north-west around day 6 (25 June), which has been blown up over the British Isles on the ECMWF 12Z run, but it doesn't have much support from the ensembles.  It looks like being near average to fairly cool until around 26-27 June, but with potential for warmer, humid air to head in from the west-north-west during the last few days of June.

The NOAA 8-14 day outlook hints at a continuation of this pattern through week 2 with a strong Atlantic ridge:

https://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

Thus, the current outlook looks "usable" but nothing spectacular.  The wet May that we've just had, and the recent rain, may prove useful, as there's no guarantee of much rain during the rest of June.  I believe that there's a fair chance of the high pressure establishing over the UK towards the second week of July, promising something warmer/hotter and sunnier, but that's a long way off.

Edited June 19, 2021 by Thundery wintry showers

[Frosty.]

There’s quite a lot of Azores ridging indicated on the GEFS 0z mean, it does wax and wane but it’s still a decent mean with some jolly nice looking perturbations which may mean that July gets off to a good start?!  

 

[DanDorsetUK]

What's everyone's thoughts about the sea temps nosediving to the North and West of UK? Is this unusual? Surely that could lead to a very severe winter coming up?

 

Edited June 20, 2021 by Dan Clow

[Man With Beard]

Quite a marked change from yesterday's 00Z ECM ensembles. Only about 10-20% ensemble members now entertaining the UK trough next weekend, most members now backing a ridge just to the west and settled conditions, though never particularly hot.

Edited June 20, 2021 by Man Without Beard

[Bradley in Kent]

34 minutes ago, Dan Clow said:

What's everyone's thoughts about the sea temps nosediving to the North and West of UK? Is this unusual? Surely that could lead to a very severe winter coming up?

 

My non expert opinion will tell me no about winter if not the exact opposite. 2015 / 2016 had a cold Atlantic which kept whipping up low pressures further south resulting in frequent southerly winds. Conversely 2010 had average to warm Atlantic anomalies.

In summer 2015 it seemed a cold Atlantic gaves us cool conditions here from chilly Westerly winds. It's obviously worth mentioning the strong El Nino though at the time.

Based on that and as someone who wants seasons to be seasonal, cold Atlantic anomalies isn't the best of news; cools it down in summer, warms it up in winter like 2011 and 2015.

[mushymanrob]

12 hours ago, Thundery wintry showers said:

My reading of the last third of June is "mainly dry but fairly cloudy", with Britain on the north-western flank of the Azores High.  It does depend on the extent of the low pressure system moving in from the north-west around day 6 (25 June), which has been blown up over the British Isles on the ECMWF 12Z run, but it doesn't have much support from the ensembles.  It looks like being near average to fairly cool until around 26-27 June, but with potential for warmer, humid air to head in from the west-north-west during the last few days of June.

The NOAA 8-14 day outlook hints at a continuation of this pattern through week 2 with a strong Atlantic ridge:

https://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

Thus, the current outlook looks "usable" but nothing spectacular.  The wet May that we've just had, and the recent rain, may prove useful, as there's no guarantee of much rain during the rest of June.  I believe that there's a fair chance of the high pressure establishing over the UK towards the second week of July, promising something warmer/hotter and sunnier, but that's a long way off.

For what its worth, i agree with your assessment, and petes "good feeling" .  Most "good" summers dont get going until July, so something should start to evolve soon. I am a bit concerned though on the 8-14 day chart that the high in the West Atlantic is expected to strengthen. That will delay any pressure build properly over the UK id have thought and keep us in a cooler NW upper flow.

But no disaster..

[Methuselah]

Aye, the Atlantic HP really can't make up its mind, regarding its final destination (not to mentions shape & orientation) which may or may not allow some sort of troughing, in our tiny part of the world; but, as has been said above, no disaster: 

    

    

    

[Frosty.]

The ECM 0z ensemble mean again looks ridgy..especially later which is pretty much what I said about last evenings 12z?...good continuity there..if anything it looks better than the previous run  although I should be comparing like for like..slaps myself on the wrist! ...perhaps it’s not a bad outlook by any means ?...longer term it might even become a good outlook..especially further south!.. ...just my amateur opinion! 

Edited June 20, 2021 by Jon Snow

[Guest]

Disappointing as we enter into high summer, very few warm ensembles members bar a couple of outliers. Little indication of warmer temps returning anytime soon. 

[Frosty.]

I’m going to use that word again... ...ridgy! ..yes that’s how I would describe the GEFS 6z mean..yes there’s wax and wane / ebb and flow but I’m thinking the longer term outlook in particular could be quite summery!..with a ridgy mean you get perturbations like this!!! ...in the meantime, the week ahead is a bit mixed for sure, and starting cool but temperatures recovering into the high teens / low twenties c further south / southeast and it looks predominantly fine, away from the far nw / n which could be rainy midweek!...all in all, it’s not a bad outlook, just not as good as it’s been recently..but that could change further ahead..small sample below! !  

 

Edited June 20, 2021 by Jon Snow

[Methuselah]

A rather 'interesting' pair of ensembles IMO: the control run & mean are both okay; though the operational is even cold outlier, in two places:  

    

It's up and down like Linda Lovelace's knickers!  

Edited June 20, 2021 by Ed Stone

[minus10]

47 minutes ago, Jon Snow said:

I’m going to use that word again... ...ridgy! ..yes that’s how I would describe the GEFS 6z mean..yes there’s wax and wane / ebb and flow but I’m thinking the longer term outlook in particular could be quite summery!..with a ridgy mean you get perturbations like this!!! ...in the meantime, the week ahead is a bit mixed for sure, and starting cool but temperatures recovering into the high teens / low twenties c further south / southeast and it looks predominantly fine, away from the far nw / n which could be rainy midweek!...all in all, it’s not a bad outlook, just not as good as it’s been recently..but that could change further ahead..small sample below! !  

 

Small sample JS...i had to stop and have a cuppa half way through 

Yes it does look a bit more promising for July from the ensembs. Gfs 6z op also showing that hopefully July will be more summery again after this bleak spell as high finally moves over us....

 

49 minutes ago, Ed Stone said:

A rather 'interesting' pair of ensembles IMO: the control run & mean are both okay; though the operational is even cold outlier, in two places:  

    

It's up and down like Linda Lovelace's knickers!  

Who?...

You are now showing your age Ed 

There is a gentle drift upwards with those ensembs, hopefully a good sign....

 

[tight isobar]

1 hour ago, Alderc said:

Disappointing as we enter into high summer, very few warm ensembles members bar a couple of outliers. Little indication of warmer temps returning anytime soon. 

You need to take the mean as the guide.. longer range.. and especially when the outliers are within its upper adjust!.. my rekonining is a stark upsurge in all members beginning to breach the mesn/ control.. quite impressively quite soon.. the temperature plots also both continue- and gain in a possible plume like spell into months end.. keep watching

[Thundery wintry showers]

Cloud amounts can be hard to pin down in this kind of mid-Atlantic/Azores ridging setup, it really depends on the specifics.  I've known plenty of such spells that were predominantly dry and cloudy with the odd bit of sun and the odd bit of rain, a good example being in late July 2010:

On the other hand, some of the charts that are being shown for the back end of June remind me of the historic charts for the second week of July 1989.  Sunshine amounts were generally high during that ridge-dominated spell, even in the north and east, with fairly warm days and chilly nights, before the high drifted east and brought a hotter, sunny spell starting midmonth.

Comparing charts like these, it appears that a lot depends on how dominant/close the ridging is.  With this in mind, the latest GFS (06Z) looks mostly dry but fairly cloudy out to T+240, but the latter stages of the ECMWF 00Z run would probably be sunny and quite warm for the majority of the country. 

In the near term, a window of dry sunny weather looks set to push south-eastwards across the country on Tuesday and Wednesday, establishing over most central, northern and western areas on Tuesday and spreading into the south-east on Wednesday, but with grey weather moving into the north-west with some drizzle near western coasts.  Then after another cloudy day on 24th with some light rain spreading from the north, we get a chilly northerly on the 25th, and then perhaps another dry sunny slot moving across the country on the 26th/27th.  I've been watching the possibility for some thundery showers to develop in places from the northerly on the 25th, but this is not certain, and relies on there not being fronts embedded in the air stream.  After that, the positioning of the ridge of high pressure is uncertain, but there's a fair chance of it generally moving closer to the British Isles.

Edited June 20, 2021 by Thundery wintry showers

[Mike Poole]

ICON 12z has high pressure starting to dominate the UK weather from mid week, hangs around too, although a trough may affect the SE bringing some thundery outbreaks.  Good run within the envelope of what is possible at the moment.

[Methuselah]

And the GFS 12Z looks okay by Wednesday. Meanwhile, the recent rain has had plenty of time to soak in . . . great for our newly-planted-out leeks!

     

[Mike Poole]

8 hours ago, Dan Clow said:

What's everyone's thoughts about the sea temps nosediving to the North and West of UK? Is this unusual? Surely that could lead to a very severe winter coming up?

 

It is interesting that the negative SST anomaly has developed so quickly.  There are a few points to note here:

The really persistent (couple of years) cold blob that we saw in the North Atlantic some years ago did very little to improve our winters, so we don’t want one of those!

SSTs do have an effect, but it is a tripole (warm, cold, warm) pattern that seems most likely to be a predictor of a cold winter.  I understand that such a pattern observed in May can reoccur in the winter months, so I would be more interested in the SSTs in late spring rather than now, as an indicator.  

SSTs now and on 10th May:

The May SSTs had a better look from the tripole point of view, although one might like them warmer further north. 

I expect an ‘interesting’ winter this year.  Still close to solar minimum, the potential to recreate similar blocking patterns to last winter (and SSTs have a role in that) is there, but hopefully we get luckier more locally in the UK with snow than last year.  

And of course, a proper east QBO winter….been elusive in recent years…

 

Edited June 20, 2021 by Mike Poole

[mb018538]

Surely the ukmo 12z is wrong tonight?!

[Mike Poole]

9 minutes ago, mb018538 said:

Surely the ukmo 12z is wrong tonight?!

Why?  It is within the envelope of possible solutions at that range.  As, unfortunately, so is GFS:

[Phil Blake]

46 minutes ago, Ed Stone said:

And the GFS 12Z looks okay by Wednesday. Meanwhile, the recent rain has had plenty of time to soak in . . . great for our newly-planted-out leeks!

     

Is there any charts to show how dry it's been recently? I don't think we have had much rain at all here in the north east since the start of June. 

[Mike Poole]

GEM looking very interesting out to T120:

Another take on a very uncertain evolution.  

[Djdazzle]

The trend away from trough domination from midweek onwards seems to be continuing.