Model output discussion - into July 2020

[bluearmy]

Ec op has dropped an upper trough in fi twice in four runs ....likely too progressive but the clusters have shown this to be a reasonable call at some point in the 11/15 day timeframe 

[Man With Beard]

Gfs 18Z is very hot for SE, and hot for some others too - the potential heat shouldn't be underestimated - it is extremely difficult to get the GFS to show 30C+ on its raw output even in top-grade plumes, so for it to show 31-33C maxes five days in a row, between D2 & D6, is really exceptional. I don't expect the UK record to go in this period, but equally it wouldn't shock me if it did.

[Daniel]

Gfs keeping the very warm air into Wednesday across Southern and South eastern parts 

[MattStoke]

3 minutes ago, Man With Beard said:

Gfs 18Z is very hot for SE, and hot for some others too - the potential heat shouldn't be underestimated - it is extremely difficult to get the GFS to show 30C+ on its raw output even in top-grade plumes, so for it to show 31-33C maxes five days in a row, between D2 & D6, is really exceptional. I don't expect the UK record to go in this period, but equally it wouldn't shock me if it did.

It’s temperature projections are shocking. 6’C too low quite widely last Friday, and that’s not a rare occurrence.

[Allseasons-Si]

You are not wrong Tam's

Looking at this evenings output it is an upgrade in terms of prolonging the heat now into mid next week with heat low/s trapped in the heat makes for fascinating output to discuss,whats not to like

suntan ready:- check

waterproof mac ready:- check

BBQ ready:- check

camera ready:- check

bring on those hot temps with the thunderstorms

a latest look at the cpc anomaly's...

as you where really with what it has been showing over the last few days with +ve heights to our NE west of Scandinavia with -ve heights over Iberia/NW Spain,upper flow SW backing west later

although slight differences with surface conditions from last evening with flow from the SE then backing ESE,looking warm to hot first 6-10 days at least

and last from me with regards to cloud,temps and PPN,forget it trying to solve this a few days out even by the next day

have a good evening

 

 

[Djdazzle]

4 minutes ago, MattStoke said:

It’s temperature projections are shocking. 6’C too low quite widely last Friday, and that’s not a rare occurrence.

Even if they were 3C under, you’d be looking at mid 30’s for 5 consecutive days.

[Djdazzle]

Just for reference, 1976 had 5 days exceeding 35C, although not consecutive.

Maybe a chance of surpassing that. We have one in the bag already from last Friday.

Think 2003 had 4?

 

[Allseasons-Si]

4 minutes ago, northwestsnow said:

The best one tonight was EC det being a party pooper.

 

And was a massive outlier in terms of 850's and pressure

Edited August 5, 2020 by Allseasons-si

[danm]

42 minutes ago, Djdazzle said:

Just for reference, 1976 had 5 days exceeding 35C, although not consecutive.

Maybe a chance of surpassing that. We have one in the bag already from last Friday.

Think 2003 had 4?

 

Just looked back at the records. Heathrow had 16 consecutive days over 30c in 1976. 

[wellington boot]

2 hours ago, Tamara said:

Self evidently this is yet more nonsense excessive hyperbole.

Ultimately, and it seems ridiculous to have to keep mentioning it on the basis of the weather to come in the days ahead for many -  the low frequency tropical signal will return and that implies upstream amplification also returning with the effect of the downstream ridge re-configuring westwards at the same time as pressure falls across NW Europe. But that  emphatically ignores several days (at least) of some highly interesting and potentially exciting weather variety - with a distinctly sub tropical theme developing.

The over dramatic "ouch" part relates to a computer model snapshot in time of the extended period - and ignores, or is perhaps more likely oblivious, to problems that exist with the timing of any return to the default pattern and also seasonal wavelength changes as August progresses and which do not necessarily compute to the same synoptic result as earlier in the summer.

Some should seriously step back and stop paying such irrational lip service to each and every capricious NWP intra day suite. But then how many times has that been said and lost in the hiatus of reactivity rather than calm and rational proactivity with a distanced eye taken to the daily number crunching. It is much more self preserving to question the intra day outcomes rather than falling on the sword of each and every one of them..

 

@Tamara I wonder if you might answer a couple of questions I have about this.

- You note the inevitability of the low frequency tropical signal returning (which you have previously described as "default") and promoting upstream amplification etc.

- You also later refer to the default pattern and seasonal wavelength changes in August.

I wonder if you could flesh this out a little more. Firstly I'm interested in what you mean by the default pattern. Do you mean on a global basis, or are you specifically referring to default patterns for a UK summer, because there seems to be an implication regarding the effects of this change on UK conditions? 

I understand that there are more and less typical broader patterns, so an Azores high is typical while a Scandinavian high is less so, but even if you imagine a default Azores high in place, there are many ways for the UK to retain a warm/continental flow, for instance, just as there are ways to be cool and wet with warm southerly or easterly draws. 

So what is the implication when you say the default pattern will return? Do you just mean, default broader patterns will return, accompanied by relatively moderate conditions and all the usual uncertainty, or are you implying specific conditions in the UK? 

I suppose I'm asking here because if default broader conditions are to be significant (as you suggest they are) in this context they must imply specific effects for local weather. And yet looking through recent summers we have had prolonged spells of both warm, settled weather (probably majority overall) as well as wetter, cooler weather, such that it is not clear to me what our default summer weather is. So it's not clear to me either what default conditions locally are, or that globally default conditions have predictable effects on weather locally...

Secondly, can you add any further detail about seasonal wavelength changes? Is this to do with the jet firing up? Does this mean August should actually be expected to be a less summery month overall than June/July? My understanding was that our recent run of our Augusts was anomalous set against long term averages.

 

A few questions in there I know. I hope you can pick that apart...

[Paul]

New thread now open here - I've split out the posts from this morning into it: