Model Output Discussion - Autumn arrives

[Guest]

7 minutes ago, Mark Smithy said:

Given that the Euro models are in agreement at the moment, as are most of the GFS ensemble members, it's the GFS operational which continues to be operating in an inaccurate world of its own. It has stuffed up on the maxima throughout this spell, so its latest outlying modelling should be taken with a health warning. Unless of course its own members and the Euro models come on board, in which case different story. For now? Be sceptics.

Hi Mark. Again, this has been proven incorrect multiple times now. Many who are refuting your baseless statements are providing data to back it up So far, I've yet to see the same from you regarding this phantom overestimating of temperatures you claim from the GFS (other than that time you cherry-picked an older model run).

 

[MattStoke]

GFS has GFS stuffed up maximum temperature projections when it’s been spot on every day  

Different interpretations are fine but outright lies just because you want a different outcome, is pathetic. Guy is a complete clown.

[FetchCB]

13 minutes ago, Mark Smithy said:

Another massive drought outlier on the 0z GFS operational. Amazingly out of step from the other members:

 

Interestingly, the 0z GFS does start the day slightly tighter to its other members on the T850. It has, correspondingly, downplayed today's maxima. It's still over the top compared to its other members however. As we know, this past fortnight the operational has been running around 2C hotter than most of its members and it has been inaccurate by about the same amount day on day.

 

 

The operational is a whopping outlier

The operational is more accurate from a modelling perspective as it is run at a higher resolution, as pointed out by Paul, than the other members. The other members also have their starting parameters changed to allow for the possibility that the initial observations may not be 100% accurate,so it is by design that they start different. 

By continuing to highlight this difference as a way of highlighting the GFS operational is somehow wrong does you no favours, it merely highlights a lack of understanding. 

In regards to the operational being a massive outlier. It is an outlier that is true, however there are some ensemble members that are fairly dry as well so yes an outlier but not massively so. 

 

 

[Guest]

4 minutes ago, Mark Smithy said:

FAX charts also show a very unstable situation going into next week. This set up combined with residual heat will produce a lot of precipitation for some.

I always favour the FAX charts, especially over the North American model when it comes to pinpointing precipitation. 

Nick Finnis' Netweather update this morning also looks to have this spot on: 

Peak of the heatwave today but the end is in sight with some welcome rain

WWW.NETWEATHER.TV

---

Heatwave will reach its peak today, with temperatures perhaps reaching 37C in southern England. Hot again Sunday before heat eases and threat of thundery downpours increases as we head through...

 

 

 

 

I don't see anyone denying the possibility of rain early next week as pressure falls and instability builds. It all looks very hit and miss though, for those parched areas with showers or thunderstorms far from the best solution to drought conditions. Further north there is a better chance of something helpful in the form of frontal rain.

Thereafter, and well outside of FAX chart range (they are indeed very useful for short term predictions), there is a strong trend - not an outlying one - to rebuild high pressure and warmth from the south. 

[MattStoke]

The ECM, UKMO and GFS aren’t to be used for rainfall amounts, anyway, particularly when it’s convective. It’s the higher resolution models that will have a better handle on it as they better resolve small scale features.

Edited August 13, 2022 by MattStoke

[FetchCB]

9 minutes ago, Mark Smithy said:

FAX charts also show a very unstable situation going into next week. This set up combined with residual heat will produce a lot of precipitation for some.

I always favour the FAX charts, especially over the North American model when it comes to pinpointing precipitation. 

Nick Finnis' Netweather update this morning also looks to have this spot on: 

Peak of the heatwave today but the end is in sight with some welcome rain

WWW.NETWEATHER.TV

---

Heatwave will reach its peak today, with temperatures perhaps reaching 37C in southern England. Hot again Sunday before heat eases and threat of thundery downpours increases as we head through...

 

 

 

 

Fax charts do not show rain, they show fronts. Fronts can and do cross the UK producing no rain, although more typically dying out as the cross the country. They do not show instability they show pressure. Low pressure does not equate to instability as there are other factors in play as was the case after the last heatwave when a low pressure moving up from Iberia produced very little rainfall in the south east due to unfavourable conditions higher in the atmosphere

You are interpreting the fax charts to suit your bias. 

 

[Earthshine]

Looks like a more low pressure dominated theme next week (let's hope for some rain in the worst affected regions!) but high pressure isn't far away.  In fact ECMWF suggesting perhaps a return to easterly winds for the last third of August with corresponding warmer temperatures.  Although even next week is looking warm still with a legacy of warmth from the last week.

[seb]

7 minutes ago, MattStoke said:

The ECM, UKMO and GFS aren’t to be used for rainfall amounts, anyway, particularly when it’s convective. It’s the higher resolution models that will have a better handle on it as they better resolve small scale features.

And the UKV has reduced convective activity by roughly half, as has the DWD’s MOS-Mix (the German version of UKV which runs to Wednesday 21z and is updated hourly). 

[MattStoke]

6 minutes ago, Earthshine said:

Looks like a more low pressure dominated theme next week (let's hope for some rain in the worst affected regions!) but high pressure isn't far away.  In fact ECMWF suggesting perhaps a return to easterly winds for the last third of August with corresponding warmer temperatures.  Although even next week is looking warm still with a legacy of warmth from the last week.

Pressure anomalous that would bring joy to many here in winter!

Don’t suppose you have the precipitation anomalies?

[clark3r]

Have to admit rainfall is looking minimal in south east in the outlook, many places could stay dry, hints of another heatwave on the gfs FI  

[AWD]

A quick run down from me before I head to the beach for the day, as there is a bit of regional bias and misconception creeping in this morning.

Firstly, next week's convective activity.  Overnight UKV run maintains a theme of a convective beginning to the new working week, as it has done for a few days now.  Detail has chopped and changed, as you would expect, but the broad theme remains.  Isolated showers/storms breaking out across Wales as early as Sunday;

Interestingly, on Monday where the Metro have a yellow advisory out for thunderstorms across the western side of the UK, the UKV shows storm activity quit widely across the SE quarter.  Worth noting some more persistent rainfall forecast for northern Scotland;

Tuesday still looks like a humdinger of a day for many in the Midland and the south;

and even Wednesday has some convective activity continuing across the SE;

So convective fans certainly have some interest for the first half of next week.

 

Temperature wise, remaining warm across England, fresher across Scotland and average in Wales;

Looking further ahead and I always prefer using ensemble products rather than the ever swinging operational output personally.  So firstly, the Mogreps suite.  Becoming less hot/warm into next week, as expected, signs of something much fresher for our Scottish friends.  There seems to be a tendancy to focus on London or SE ensembles only, so for balance I will include both the London set and Glasgow set to show the differences between north and south next week, as we are all from different places around the UK.  

Clearly a more notable cool down for our Scottish friends;

Rainfall wise, the Mogreps doesn't have much for anywhere.  Convective rainfall for London for a while, more lighter stuff further north possibly;

Definitely a sign for something for the SE there, but not much.

The GEFS and EC ensembles are similar, perhaps slightly wetter on the GEFS;

With the GEFS forecasting the Icelandic low to be closer to Scotland, they do produce quite a bit more rainfall compared to the Mogreps there.

All in all, a more typical north/south split likely through next week.  

[Earthshine]

27 minutes ago, MattStoke said:

Pressure anomalous that would bring joy to many here in winter!

Don’t suppose you have the precipitation anomalies?

Signal in the precipitation anomalies aren't quite as strong:

ECMWF charts catalogue has a huge number of interesting charts/plots! https://apps.ecmwf.int/webapps/opencharts/?facets={"Range"%3A[]}

[Cambrian]

It’s been an exceptional summer - completely fascinating to follow the models and to read all the great posts - if anything though, it’s been too exceptional, and I hope it remains an exception for many years to come. I fear that it won’t. Look at that for Northern Hemisphere heat this afternoon, and the UK and Ireland very much in the thick of it. A bit parky over Greenland though. 

There is plenty of the summer left for some more great summer weather, with the heat in time subsiding, but summer far from over, though focusing on the realistically modellable next 10 days or so, we’re eventually getting into something a bit more normal - a reversal in the mean anomalies between today through to day 9. ECM / GEM / GFS 0z runs.

   

Lower pressure, slightly negative to neutral height anomalies - clearly not going to be autumnal, but definitely much closer to normal, gentle weather from the west, fresher with a reasonable chance of a good bit of rain for many in the next week and a half. Probably a bit hit and miss at times but there we go. 

After all the extremes, there’s going to be nothing wrong with a spell of normal weather!

[MATTWOLVES 3]

There is no washout whatsoever for many moving forward! That's not me hoping for an extension of summary conditions because rainfall is badly needed for many areas!.

But I feel the first few days of next week are only hope for some time...once again the GFS 0Z mean extends Heights towards the South and these extend further North with time. This month not bucking the trend of what's come before it so far.

Edited August 13, 2022 by Paul
Removed the quote and response to the post in question, as the original post has already been removed.

[Paul]

Parts of the east and southeast certainly doen't see much rain through the ECM 00z run -  10mm or less for some. Plus, some of that will be convective which'll be hit and miss with some seeing more, other less, most probably. 

https://www.netweather.tv/charts-and-data/ecmwf

 

[Paul]

Just looking at the GFS Ensembles and if it weren't becoming such a serious situation the heatmap would be quite comical with hardly any rain showing up, yet again. (This is a new chart type, not live on the site yet btw - the scale probably needs a bit of tweaking).

The 90th percentile (top of the greyed out part) is a good guide as to what's most likely to happen imo, as it removes the outliers from the picture, and taking that, it's not disimilar to the ECM, with 10-15mm ish across the run for London. Not even close to making a dent in the deficit. There are some much wetter possibilities shown as well though, which can't be discounted - especially as it's going to be convective, localised rainfall. 

[Man With Beard]

Are thunder lovers going to get their fix this week? The ECM shows a thunder threat spanning several days.

Precip and temperature values are to be taken with a pinch of salt IMO. If a lot of convective activity pops up, temperatures could be massively suppressed on any one day, but if the ECM is to believed then taking into account its habit of undershooting maximums, we'll still see nationwide peaks of 27-28C throughout the week. Not exactly a cool-down. That said, raw values for this model are more reliable in cloudy, less settled weather.

[slater]

Lots of mix messages on here about rainfall for the start of next week. 

[Captain Shortwave]

Or it could be because the rain is in the form of showers. As such runs will vary considerably regarding rainfall amounts.

[MATTWOLVES 3]

4 minutes ago, NTC said:

The heatlovers like MattWolves, Seb, Scorcher don't want it to end, the heathaters want it to end, so the former see any rain as unlikely because it's been dry for so long the latter see any map with a blob of rain on it as a sign the heatwave is over. There are few on here who sit in the middle, so when it comes to the weather the extremes  will use any chart that proves their point of view. The lack of JonSnow posts recently suggests to me the heatwave is ending from Monday.

That's not the reason jonsnow is not posting...he's taking a few days out which he does from time to time..And I'm pretty sure he would have a positive spin on things if he was posting! It's a bit foolhardy to say if a certain poster is not posting that spells the end of a certain Weather type! Unless that said poster as access to certain information the rest of us don't!

My honest thoughts on these conditions were based on the fact I've seen these repeating patterns many times over previous good Summers and this one has been following the previous scripts. I'm also seeing a  very solid mean which indicates a good chance of a recovery of pressure...if I was seeing full blown low after low with Heights pegged back much further South I would be calling it as looking poor!

But in all honesty I and the other posters you quote are seeing exactly the same thing.

[bluearmy]

 - slp is falling and there are fronts associated with the slow moving lows - but heights remain fairly high over se half of England (c 560+) so the amounts of precip are unlikely to be enough to make a difference. anything welcome of course. Convective storms could even be worse in the sense that they could introduce flash flooding with the run off from the concrete like grass surfaces.

looking further ahead and the eps has mean slp 1020hpa+ back end week 2 with associated heights high 570’s

that should lift confidence around a decent BH weekend 

Edited August 13, 2022 by bluearmy

[viking_smb]

Brickfielder posted a good post just now over on the convective thread

[sheikhy]

Not sure i believe ecm precipitation amounts anymore anyway!always over doing it just like the ukmo!gfs worryingly is a lot drier on its 00z run!!looks like monday is the last real hot day of this spell!

[Lord Grogon]

20 minutes ago, NTC said:

The heatlovers like MattWolves, Seb, Scorcher don't want it to end, the heathaters want it to end, so the former see any rain as unlikely because it's been dry for so long the latter see any map with a blob of rain on it as a sign the heatwave is over. There are few on here who sit in the middle, so when it comes to the weather the extremes  will use any chart that proves their point of view. The lack of JonSnow posts recently suggests to me the heatwave is ending from Monday.

It will always be very difficult to get a truly balanced analysis in an internet thread with hundreds of posters with varying levels of skill, experience and biases. Key I think is to pick a few people who seem reliable and treat everything else as a bit of fun. The “Pro” label is pretty useful as that select few on here definitely seem to analyse the data first with any personal preferences kept strictly second. 

Personally I quite enjoy reading the ups and downs. It’s just us being human. Only thing that bugs me is when people just say an opinion with no context e.g. “awful ECM today!” It adds nothing and simply clogs the thread.
 

[MattStoke]

56 minutes ago, Man With Beard said:

Are thunder lovers going to get their fix this week? The ECM shows a thunder threat spanning several days.

Precip and temperature values are to be taken with a pinch of salt IMO. If a lot of convective activity pops up, temperatures could be massively suppressed on any one day, but if the ECM is to believed then taking into account its habit of undershooting maximums, we'll still see nationwide peaks of 27-28C throughout the week. Not exactly a cool-down. That said, raw values for this model are more reliable in cloudy, less settled weather.

UKV shows how showers/thunderstorms may suppress temperatures but how warm it could get given any sunshine with broadly quite high temperatures shown in the east for Monday but pockets of low temperatures where it’s modelling showers to occur. Not to be taken literally on where it has those lower pockets of temperatures, of course, as modelling individual showers is very difficult.

Edited August 13, 2022 by MattStoke