Model Output Discussion - The Start Of Summer

[danm]

1 hour ago, StormChaseUK said:

Yes a lot of rain , this could be one of the worst summers we have had since 2012. It could even beat 2012 for rubbish weather

You must be a WUM. 

Early days for summer 2019. Mixed bag of weather over the next week, still some way off anything settled. However the overnight runs, while far from verifying, shows things can and do change quickly. Keep the faith. 

[StormChaseUK]

3 minutes ago, danm said:

You must be a WUM. 

Early days for summer 2019. Mixed bag of weather over the next week, still some way off anything settled. However the overnight runs, while far from verifying, shows things can and do change quickly. Keep the faith. 

No wind up about it, it just looked like a lot of rain on those charts for SE/East

[Wimbledon88]

Certainly looks like an unsettled and pretty wet couple of weeks coming up for most of England and Wales. Latest update from Met would appear to back that too. 

[Weather Boy]

27 minutes ago, danm said:

You must be a WUM. 

Early days for summer 2019. Mixed bag of weather over the next week, still some way off anything settled. However the overnight runs, while far from verifying, shows things can and do change quickly. Keep the faith. 

For the benefit of newer model watchers. StormChaseUK is making a ridiculous statement.

The models are usually pretty sold for maybe a week ahead, and one can look at trends for perhaps two weeks ahead. To suggest that they are worth taking seriously  beyond that timeframe is for the birds. Sometimes even within a week there can be doubts, even for the general trend, and contradictions between the models.

Some of the more knowledgeable posters on here (see, for example, Tamara's post I think it was yesterday) try to look at long term trends using background signals that are way beyond me. But even they will admit that this is taxing, fraught with difficulty and often wrong. Even these exercises will not normally look much beyond a month, certainly not with any confidence. Seasonal forecasts are extremely difficult and certainly not based upon a few days' of operational model output.

So, anyone attempting to make a prediction for an entire season during its opening days based on current model output hasn't a clue (or is, as Danm implied, doing it for their own reasons). They might be right of course, but if they are it will be because the weather happens to tie in with what they said by coincidence, not because they were interpreting the models correctly.

I hope this is of benefit to those possibly confused by such comments.

[danm]

33 minutes ago, StormChaseUK said:

No wind up about it, it just looked like a lot of rain on those charts for SE/East

I was referring to your comment about this summer being worse than 2012, even though we’re only 6 days in....

[StormChaseUK]

Ok well I would love to be wrong. It's not a case of wanting to be right that it will be an awful summer it just looks that way

Infact I would love to be wrong as that would mean better weather!

Edited June 6, 2019 by StormChaseUK

[Polar Maritime]

If anyone wants to chat about Summer and what they 'think' is in store please head over to the Summer thread.

This thread is for model output based discussion only.

Thanks.

Edited June 6, 2019 by Polar Maritime

[Big daddy 49]

As a casual reader of these pages,can I ask how you can say July and August are going to be awful,when I’ve always understood that the weather can’t be accurately predicted more than a week in advance?.

[weathermadbarnsleylad]

As I said a few days ago in my posts. Don't trust the models at the moment after 5 days. It's could change in a flash. As seen with 00z and 006z. All those people that are saying summer is over. Get a grip. 

[knocker]

Neat 1399 UTC sat image indicating the low/occlusion feature and the convergence zones

[knocker]

Any rain and showers will largely have died out by 2100 this evening leaving a clear night for most places, But moderate rain from the low and fronts to the south will ingress the south west from midnight on it's way north

[Tamara]

27 minutes ago, Weather Boy said:

For the benefit of newer model watchers. StormChaseUK is making a ridiculous statement.

The models are usually pretty sold for maybe a week ahead, and one can look at trends for perhaps two weeks ahead. To suggest that they are worth taking seriously  beyond that timeframe is for the birds. Sometimes even within a week there can be doubts, even for the general trend, and contradictions between the models.

Some of the more knowledgeable posters on here (see, for example, Tamara's post I think it was yesterday) try to look at long term trends using background signals that are way beyond me. But even they will admit that this is taxing, fraught with difficulty and often wrong. Even these exercises will not normally look much beyond a month, certainly not with any confidence. Seasonal forecasts are extremely difficult and certainly not based upon a few days' of operational model output.

So, anyone attempting to make a prediction for an entire season during its opening days based on current model output hasn't a clue (or is, as Danm implied, doing it for their own reasons). They might be right of course, but if they are it will be because the weather happens to tie in with what they said by coincidence, not because they were interpreting the models correctly.

I hope this is of benefit to those possibly confused by such comments.

There is some sense within that post and I certainly agree with the opening sentiment that also applies to a core small number who persist in ignoring any objective discussions and instead appear determined to make this thread an unhelpful and tedious read. I guess that is where the ignore facility comes in use to provide some respite, though a big shame it doesn't also block out the text when these posts are responded to.

The section about "background signals" though, like I said yesterday very often is misunderstood and misrepresented at all times of year. This term, is very overused and loses its true meaning and purposes. More specifically and accurately, it is a non numerical evidence based diagnostic process to identify the drivers at any given time that NWP is making its own calculated interpretations of. This means that if used objectively, it can provide a very useful insight into the range of possibilities within deterministic solutions and identify where patterns may change (or may not change where indicated to) based on a range of recurrent intra seasonal wind-flow signals and torque mechanisms that relate to the laws of conservation of atmospheric angular momentum.

The diagnostic looks at wind-flow mechanisms which steer the jet stream and give clues to where changes may occur based on a range of teleconnections and proxy data which are well identified to produce specific synoptic responses within given ranges of parameters at different times of the year. It is not a stand alone approach and combines with other seasonal factors that include stratospheric and sea ice trends and states which can alter these synoptic responses. 2018 to 2019 alone has been a powerful example of this sort of complex blend of factors, which sometimes have a-typical and countervailing aspects and make deciphering aspects of weather pattern modelling highly challenging for the best professional minds - let alone the enthusiastic student with the curious mind at home.

So the likes of the Global Synoptic Dynamical Model (GSDM) is a diagnostic supplement to purely NWP driven investigation, but NOT a silver bullet with sole purpose to endorse human weather preference from one season to another - though clearly there will be times when given factors will combine to include such a preferred solution within the overall diagnostic which may point to more than one possible solution in addition to the bias solution.

The problem with threads like these, and its especially poor in winter with the huge volume audience all baying for one popular outcome, is that the bias preference overwhelms everything and people will latch onto the "background factors" if the diagnostic happens to suggest a percentage probability of the desired solution...but will choose to ignore any other solution. Other times, members will migrate to any NWP which may be following a signal that doesn't even exist within the diagnostic - and that is a time to not bother posting otherwise because such analysis would be considered being a "killjoy".

Of course whichever route is taken, the end result is the same when the desired solution doesn't verify (which tends to happen more times than not when any selective process is undertaken). Irrespective of the reality, it will the be the "background factors" which are to blame - not the consensus bias of people who took the NWP model(s) at face value. And so it goes on from one season to the next and from year to year, with some none the wiser.

So I don't accept its the diagnostic "background signals" that are wrong - its the human interpretation and applied bias use of them that inevitably increases error rate.

So what is new today, away from the flurry of intra day reaction and overreaction to specific NWP outputs?

This is interesting in terms of where convergence of tropical convection may be adjusting in the Pacific, at the same time as changing the Indian Ocean Dipole signal. Redolent of a semi quasi centrally based neutral/ El Nino type signal or very weak "Modoki".

To try to put this into simpler language - This comes about through the effects of trade wind increases in the central and eastern Pacific, augmented by suppressed phases of MJO convection such as currently being witnessed as the active MJO passes through the I/O resulting in increasing cooling of the surfaces of the eastern ENSO Equatorial zones through upwelling.

However, at the very same time, there is an opposite eastward moving current to observe in the Western Pacific which creates a convergence zone of maximum downwelling and consequential surface warming in the W/C Pacific. This convergence zone consequently spawns an ideal site for tropical deep thunderstorm convection development n tandem with a similar trend in the Western Indian Ocean where downwelling currents also create favourable cyclonic convection sites.

Putting the two opposite co-existing signals in the tropics together, the net result of this is to create an a-typical Nino atmospheric imprint (La Nina like) on the rossby wavelength whilst the MJO imprints the warmest zone in the I/O but then defect also to a constructive coupled response in the Pacific when the wave phase propagates this region of the tropics.

Why does any of this matter this far away?

It matters because the tropical phase will be induced to produce the type of downstream response we are seeing at present with a downstream trough when the I/O low frequency signal engages, but with a tendency to contrasting signal of Atlantic trough and downstream ridge when the Pacific convective signal engages - and hence the opportunity for warm and settled spells maximised at this time.

Its yet another of the factors that could be shaping this summer and why numerical models may be subject to curveballs due to a twin aspect tropical>extra tropical wind-flow signal. Something else to chew on while the rest of the previous analysis remains consistently on course at present.

So, still cuing up some kind of mid month onwards shift :

With the SOI still in negative territory reflecting the continued presence of a weak El Nino signal despite the destructive action of the supressed phase of tropical convection :

and relative global atmospheric angular momentum still above average

and with the active phase of the tropical cycle set to approach the Pacific from mid month...

..reflected by associated further rise in angular momentum tendency at precisely the same time as westerly wind bursts replace the supressed phase and easterly trade wind uptick..

...then the pressure is growing for NWP to start reflecting a more downstream high pressure outlook and some kind of trough response in the Atlantic rather than the UK.

But with the principle of the diagnostic in mind as discussed above, there is likely to be associated risk probabilities to continue to observe.  The fly in the ointment remains the very stubborn  -ve zonal flow at higher latitudes which continues to negate some of the more favourable warmer and especially settled aspect to the pattern, but this too should come under increasing pressure with summer seasonal wavelength changes as long as the I/O tropical signal does not start to dwarf the Pacific and become the more default response

The latter will have to be continued to be carefully monitored, but plenty to observe as antidote to NWP derived swerves in temperament.

 

[MATTWOLVES 3]

Thanks Tamara, excellent post as always. Just looking at the icon 12z run...and one thing for sure is... Its warming up. W/NW areas look like doing pretty well with high pressure being the key player... Notice how icon also shows low pressure to our SE.. meaning there will be an ongoing risk of rain and showers, even thunderstorm activity, and more especially in this SE quadrant... Not cast in stone has its an operational run, but the indicators are there. 

[Fourty Point Three Degrees]

4 hours ago, Ed Stone said:

Here's one you would have written-off earlier:  A HL block, on June 5th, doesn't a washout summer make...

If the NAO was looking as negative in June 1984 as it is today i'd have written off 1984 like a flash.

[Methuselah]

8 minutes ago, 38.5*C said:

If the NAO was looking as negative in June 1984 as it is today i'd have written off 1984 like a flash.

You make seasonal weather-forecasting sound so simple... Anyway, back to what today's models are showing:

Warming-up with time, generally, though unsettled in the SE...?

[mb018538]

No comments on the 12z runs.....and i’m not surprised. Truly dreadful, flooding rains and cool. Let’s see what the ecm says later.

 

[Fourty Point Three Degrees]

What a superb stunning end we have to the GFS 12z....

[Mr Frost]

22 minutes ago, mb018538 said:

No comments on the 12z runs.....and i’m not surprised. Truly dreadful, flooding rains and cool. Let’s see what the ecm says later.

 

Not sure about that mate - personally I will be enjoying some fine, sunny and warm days. (Numerous if this GFS 12z run becomes reality!)

Many others around the UK and Ireland will also be sunbathing on quite a few days - especially our Irish/Northern Irish friends.

I will take this run all day long for early Summer - let’s keep the real heat for July. 

[MATTWOLVES 3]

Very poor away from the NW... Fair play Mr frost... Hopefully some nice weather coming your way... I'm trying to find some positives here.. But that's like putting a fur coat on a pig... Pretty pointless... Gem is let's just say.... Not priceless... But bloody pointless.... 

Edit... Its rubbing off on me... Mr positive is becoming Mr negative...

Edited June 6, 2019 by Mattwolves

[Scorcher]

12 minutes ago, 38.5*C said:

What a superb stunning end we have to the GFS 12z....

Seriously, it's getting very tedious indeed reading your repetitive, negative posts. There's about 3 or 4 of you who are constantly on here at the moment, childishly going on about how miserable everything is going to be. I just despair every time I'm about to click on the Model thread, and you've made the latest post. It's certainly making this thread miserable reading that's for sure!

[mb018538]

12 minutes ago, Scorcher said:

Seriously, it's getting very tedious indeed reading your repetitive, negative posts. There's about 3 or 4 of you who are constantly on here at the moment, childishly going on about how miserable everything is going to be. I just despair every time I'm about to click on the Model thread, and you've made the latest post. It's certainly making this thread miserable reading that's for sure!

To be fair, a lot of locations are forecast to receive over a months worth of rain in the next 10 days. I’d say that qualifies as pretty miserable, especially for high summer!

 

[MATTWOLVES 3]

Again... The 12z operational was bad, and most definitely in places a cold outlier... The mean looks similar to earlier, the rainfall spikes don't point to an Oxford boat race either..... Now take a step back... And breathe deeply folks...

[Djdazzle]

1 minute ago, mb018538 said:

To be fair, a lot of locations are forecast to receive over a months worth of rain in the next 10 days. I’d say that qualifies as pretty miserable, especially for high summer!

 

Yes, but there are other options on the table. One GFS op run which is extremely unlikely to verify.

[Methuselah]

1 minute ago, Djdazzle said:

Yes, but there are other options on the table. One GFS op run which is extremely unlikely to verify.

Indeed there are, Dj...One of them is even called the weather!

[Guest]

13 minutes ago, mb018538 said:

To be fair, a lot of locations are forecast to receive over a months worth of rain in the next 10 days. I’d say that qualifies as pretty miserable, especially for high summer!

 

It's  a little vague that statement. Some said the same thing about Friday's system (correctly at the time) but for many rain-starved areas the totals have been significantly downgraded. It's far from perfect summer weather, but it's also not the relentless doom and gloom that the likes of @38.5*C like to troll us with.