Model output discussion 9th April onwards

[mushymanrob]

2 hours ago, Alderc said:

On the face of it pleasantly warm at day 10 on ECM. 
 

 

However looking at the detail, there’s a massive undercut on the ECM right across the south and east through weekend. 

Sunday 

Monday

Still lots of potential but the surface output is pretty pants this morning on the Ops runs but fortunately the GFS Ops is very much in cooler end of the ensembles, which are on the whole extremely positive (in fact probably the best of summer) 

 

You make a fair point, and whether that undercut becomes manifest or not is of course uncertain and completely dependent on the exact centre track of the high. At this stage, nothing to worry about but if its still there on Thursday... maybe!

[Frosty.]

Well, what can I say!.. ...the ECM 0z ensemble mean becomes the BEST I’ve seen it so far in the build up to this pattern change!!... ...we may have found the pot of gold at the end of the  

[Northwest NI]

Looking particularly good for Ireland, this developing high.

 

 

Edit: after scrolling back a bit, I see this has already been mentioned…..

Edited July 10, 2021 by Northwest NI

[mb018538]

6z is another largely forgettable op run, with the high quickly swept away and gone by Monday…

[Guest]

GFS caves in high pressure again really quickly around the 19th….before then 3-4days of low to mid 20s. Might be another outlier but two Ops runs on the trot now…

And Ed please don’t post this saying ‘Loks nae bad’ because it’s rubbish. 

 

Edited July 10, 2021 by Alderc

[kold weather]

The GFS/GEM this morning showing what I did warn could happen and that the HP ends up getting shifted further and further north/north-east that we end up getting into a undercut situation.

I think thats probably more likely atm than the ECM solution, if only because that is broadly the pattern we've been pretty locked into for the last few weeks with diving lows getting caught as HP develops to the north and around the HP, which is why the SE has been so wet.

The ECM is better but it still shows a variation of that risk, particularly for the south/east where there is alot more cloud about. Still its better longer term though than the others.

Probably the more north/west you are the safer you probably are in such a set-up like this.

Hopefully the GFS/GEM move away from the suggested set-up and towards a more sustained HP spell again. 

[Timmytour]

1 hour ago, Jon Snow said:

Well, what can I say!.. ...the ECM 0z ensemble mean becomes the BEST I’ve seen it so far in the build up to this pattern change!!... ...we may have found the pot of gold at the end of the  

A run of consistently nice charts that all coincidentally follow on from St Swithin's Day  <crosses fingers> 

[Scorcher]

Again another strange run from the GFS.

I'm suspicious of how such a robust and strong area of high pressure which begins to move in on Thursday suddenly weakens quite dramatically.

The 00Z was basically bottom of the pack earlier on and I reckon this isn't much better.

[mb018538]

2 minutes ago, Scorcher said:

Again another strange run from the GFS.

I'm suspicious of how such a robust and strong area of high pressure which begins to move in on Thursday suddenly weakens quite dramatically.

The 00Z was basically bottom of the pack earlier on and I reckon this isn't much better.

Because it’s the UK? If it was anywhere in Eastern Europe it’d Just sit there for a few weeks. We wait a month for a proper high to build in and it’s gone in days, law of sod says so

[Frosty.]

56 minutes ago, mb018538 said:

6z is another largely forgettable op run, with the high quickly swept away and gone by Monday…

Don’t follow every op as if it’s gospel!!!..stick to the mean..or better still, the anomalies.. ..you know it makes sense! ..

 

Edited July 10, 2021 by Jon Snow

[Guest]

Again clearly the GFS Ops run from the 06Z suite was way out of kilter with its ensemble pack. Hopefully it’s just wrong but certainly not unknown for the GFS Ops run to paint a dismal picture only for it to come off, especially in the May just gone. We’ll likely need to sit tight for a few more days yet……

[Don]

1 minute ago, Alderc said:

Again clearly the GFS Ops run from the 06Z suite was way out of kilter with its ensemble pack. Hopefully it’s just wrong but certainly not unknown for the GFS Ops run to paint a dismal picture only for it to come off, especially in the May just gone. We’ll likely need to sit tight for a few more days yet……

This has happened in recent winters too when the op goes mild and against its ensembles, only for them to follow suit later.  However, plenty more twists and turns to come and I would say at this stage, a period of warm/summery weather is odds on, albeit (hopefully!) not too hot.

[Scorcher]

59 minutes ago, mb018538 said:

Because it’s the UK? If it was anywhere in Eastern Europe it’d Just sit there for a few weeks. We wait a month for a proper high to build in and it’s gone in days, law of sod says so

I'm surprised you and Alderc actually follow the models and don't simply follow sod's law all the time...

We do get highs that stick over us at times- the one next week looks the strongest high I've seen for some time in the summer months which is why I'm dubious about the GFS evolution.

[kold weather]

The only thing to note is the GEM also looks quite progressive. 

They both maybe wrong at this stage, but its a signal that needs watching, especially given the relative persistence of that kind of pattern in the last 2 months...

It Also wouldn't be the first time the models gave attempted to bring HP in only for it to end up not coming off in the last few weeks, though this is by far the strongest push of the summer thankfully.

Hopefully regardless we can get the HP close enough for a lovely few days at the back of next week/weekend. Lots can change in that time in all fairness as well.

Edited July 10, 2021 by kold weather

[Frosty.]

I’m actually astonished by the continued negativity!..given how great the ECM 0z ens mean looks..as well as all the other great output..jeez  ..for example!..I’m really just stupefied (probably the wrong word)...do I look..   like I care!!.. ...is that even a word..stupefied ?... ..ps.. I’ve had clarification..stupefied is a genuine word..yay ! ..    

Edited July 10, 2021 by Jon Snow

[MATTWOLVES 3]

1 hour ago, Jon Snow said:

Don’t follow every op as if it’s gospel!!!..stick to the mean..or better still, the anomalies.. ..you know it makes sense! ..

 

I'm bemused Karl...For me the GFS is by far the worst  set of operational runs I've ever seen in my life..not just in Winter but in Summer also! I think Steve M was bang on when he used to get so agitated over people's reliance on that model. You can tell in here already a few are ready to have hissy fits over another couple of shoddy op runs...Well unless Exter say its not happening I'm inclined to not get to downhearted! And like you say why do so many ignore the anomalies and the means,and all the individual ensemble members! The 6z mean looks just fab! 

I'm not gonna spend my Weekend stressing over a few will it or won't it GFS op runs..let's bring it home

PS I look forward to Petes its nae looking to bad summary very shortly

Edited July 10, 2021 by MATTWOLVES

[Tamara]

On 24/06/2021 at 14:47, Tamara said:

What is key is that peak summer wavelengths, allied to the lack of any sustained -ve inertia within the atmosphere, and which was covered in a lot of analysis the other day, look set to augment a subtle eastward shift in the pattern, with time, and set up something of a weak -NAO signature in the Atlantic, but crucially disconnected to a mainly +AO polar profile. The main jet stream to the north, as accurately depicted in the quoted summary, having that slight split flow aspect to reinforce the weak troughing close towards the Azores area.

Bom dia

The gist of split flow, as suggested in the quoted post of the other week, proved consistent enough - but equally -ve inertia between the tropics and extra tropics has clearly proved stronger than anticipated and this has resulted in a much more Nina-ish aspect c/o a very -PDO profile upstream which has seen troughs splitting SE'wards into NW Europe  rather than the retention of a downstream ridge more (Nino-esque) that had been previously discussed and shallow troughs stalled/disrupted further west.

This has maintained cooler air advection from a NW vector and kept the lid on summertime heat build over Southern Europe. and any chance of it spreading outwards.  Indeed even in my own locale 1200 miles further S/SW than the UK and other parts of NW Europe, the cooler air advection and Atlantic influences have just about penetrated this far south. Pressure has remained high though and squeezed any residual frontal rain from the main troughs sinking close to S UK and the nearby continent.  A few bands of variable amounts of cloud have been the sole product and temperature have been in a range of 23 to 26C during these cooler air advection incursions and 28 to 32C as the Azores ridge retains its full seasonal control once more. The lower mid banding of these values are cooler than average for the time of year for much of central and southern parts of Portugal.

This weekend repeats that sequence with, this time, a very brief visit of heat from Africa before the next cooler front arrives tomorrow. Values of 35C seen here very locally yesterday, 37 to 41C expected locally> regionally today before back down to 25C by Monday...and then heating back up once again by Weds/Thurs next week

That leads nicely onto the here and now into the outlook period and whether or not this summer cycle keeps rinsing and repeating.

NWP has tried a couple of times to suggest north eastward ridging of the Azores High to more north western parts of Europe, but has subsequently kept the ridge more retracted and allowed another trough to slip south around its perimeter. 

At this point the diagnostic GSDM data closely reflects the Nina-ish NWP pattern and why the numerical models have backtracked to the default pattern since the middle of June: :

Relative total angular momentum capitulated the buoyant levels of early June and has operated a deficit of between -1 and -2 SD (standard deviations) since the middle of June. 

 

Strong trade winds across the Pacific and tropical convection rooted across the Indian Ocean has sustained -ve extra tropical mountain torque across Asia and extended the wavelength of a retrogressive downstream pattern much longer than anticipated in a previous post. Previous activity and strength of eastward propagated tropical convection has not sustained as had been previously discussed.

 

The Global Wind Oscillation, a phase plot depiction of wind-lfow inertia within the atmospheric circulation has orbited into the La Nina attractor phases 1/2/3 at a greater amplitude than previously suggested.

 

This adds up to the stubborn Atlantic ridging and peripheral shallow troughs circulating around the high pressure into north west europe c/o the accented -PDO profile and despite a largely +AO profile. The latter persisting as suggested, the former clearly underestimated.  

NWP ensemble products are more closely congregated around in achieving Azores ridging into more NW parts of Europe in the mid term, but with some retention thereafter of defaulting back to the lower angular momentum regime. Its easy to see why this might be the case and why some caution about longer range numerical products can be understood. It is important, based on AAM falling further than anticipated within the last few weeks, that sufficient momentum builds from upstream to enable this to happen c/o rossby wave propagation from tropics > extra tropics. This is also not made a simple equation due to the stubborness of the -PDO which is aided by the strongly imbalanced polar ice melt and recent extraordinary temperatures at latitudes that should not see such values. 

Its a difficult situation judging the further outlook but from the diagnostic point of value, momentum will need to take the GWO out of the Nina phases 1,2 and 3 into Phase 4 to meet the longer range NWP signal for NW European mid latitude high. This can certainly be achieved, but any shortfall or weak eastward propagating orbit, allied to the polar> mid latitude feedbacks mentioned could mean that a retrogressive correction happens subsequently.

From my own point of view this maintains relatively cooler interludes  (still pleasantly warm) to a generally standard very warm regime (albeit cooler than regional average) and means a good summer is assured -  but for the majority in the UK it is easy to understand why its very important that the present indications are satisfied and so summer proper can be enjoyed

Até breve

 

Edited July 10, 2021 by Tamara

[Guest]

4 minutes ago, Jon Snow said:

I’m actually astonished by the continued negativity!..given how great the ECM 0z ens mean looks..as well as all the other great output..jeez  ..for example!..I’m really just stupefied.. ...is that even a word?... ..ps.. I’ve had clarification..stupefied is a genuine word! ..   

It’s not being negative Mr Snow, it’s being realistic. There’s undoubtedly good signals in the ensemble packs however it would be silly to ignore the solutions that don’t paint a great picture, even more so when the when those are the exact solutions that have pretty much won out since the start of May (down here at least) 8 or 9days ago all the models were hinting high pressure would be parked over the UK now and temps into the mid twenties, look where we are, currently 4-7C below average across large parts of the south. 

[Frosty.]

1 minute ago, Alderc said:

It’s not being negative Mr Snow, it’s being realistic. There’s undoubtedly good signals in the ensemble packs however it would be silly to ignore the solutions that don’t paint a great picture, even more so when the when those are the exact solutions that have pretty much won out since the start of May (down here at least) 8 or 9days ago all the models were hinting high pressure would be parked over the UK now and temps into the mid twenties, look where we are, currently 4-7C below average across large parts of the south. 

All I can say is, remind me never to visit bournemouth, the micro climate down there sounds crap! ...there’s fantastic support from the mean charts for summery weather to return...a few rogue op runs count for nothing!  

[stodge]

Afternoon all

As usual, @Tamaraputs it far more eloquently than I ever can - my brother is currently in the Canaries and today they are having showers and 24c before the sun returns from tomorrow.

The 00Z ECM did look encouraging but the 06Z GFS does not with the "rinse and repeat" pattern of the attempted ridging NE of the Azores HP being only partially successful before the trough sinks SE back across NW Europe - to be fair, for northern Britain this doesn't remain a bad evolution with heights to the north while southern Britain has periodic interruptions of unsettled conditions as the trough sits over the Channel or northern France.

I wonder if we might have to wait for some extra-tropical energy to give the Azores HP a "kick" into Europe but there's little sign of that yet.

[kold weather]

1 minute ago, Jon Snow said:

All I can say is, remind me never to visit bournemouth, the micro climate down there sounds crap! ...there’s fantastic support from the mean charts for summery weather to return...a few rogue op runs count for nothing!  

I'd say its the opposite, the ops runs need to be taken very closely in this sort of set-up, the ensembles typically struggle to pick out little lows and the mean charts will absolutely not pick up such features that could cause an earlier breakdown at this range. How many times have we seen cracking ens means in winter only to see the ops pick up little lows that scupper the whole thing in the past?

Tamara has laid out very nicely how on a knife edge we are. The ECM looks like it manages to lock in the pattern but the GFS/GEM just keeps it as a brief interlude before the whole lot shifts back into the same sort of pattern we've seen countless times already.

As Tamara said, there is definately a route open to more sustained dry/warm weather, but its very far from a lock at this stage and I'd argue we've probably taken a step away in the last day from that solution.

I happen to think also it will lock in at some point for a 1-2 week period, its just I think we may have to wait a couple more weeks yet and have another bite of the cherry so to speak.

[Methuselah]

Well, due to popular demand, I think it's fair to say that the GEFS temperature ensembles are nae bad. And, though nothing is certain, the colder blip, around July 22, is confined entirely to the op. (the control's blip comes along later!) Only time will tell?

    

[Guest]

13 minutes ago, Jon Snow said:

All I can say is, remind me never to visit bournemouth, the micro climate down there sounds crap! ...there’s fantastic support from the mean charts for summery weather to return...a few rogue op runs count for nothing!  

Well firstly the Ops runs are a much higher resolution than their ensemble counterparts so should never be completely discounted, especially when a couple of the Ops runs from differing models together go against the means just like they did this morning. 
 

As for here its been utterly terrible, the last 22days average max is just 18.7C and only once has it reached average of 22C. The stats don’t lie, that’s dreadful. 

 

Edited July 10, 2021 by Alderc

[Frosty.]

8 minutes ago, kold weather said:

I'd say its the opposite

That doesn’t surprise me!  

[Frosty.]

12 minutes ago, kold weather said:

I'd say its the opposite

That doesn’t surprise me!  

 

duplication.. ..I really should know better, only been here for 16 years..  

Edited July 10, 2021 by Jon Snow