Model Output Discussion - Autumn arrives

[FetchCB]

1 hour ago, Mark Smithy said:

12z GFS operational is a drought outlier:

 

Something that's really odd about the operational at the moment is that it doesn't even start in the same place as the rest of its members. It actually begins 2C warmer than the rest.

No wonder it keeps showing temps that are 2C too high if it can't even get out of the blocks right.

That's because each member is started with slightly different parameters to allow for the fact that initial observations are not statistically perfect 

Ensemble forecasting - Wikipedia

EN.M.WIKIPEDIA.ORG

 

Edited August 12, 2022 by FetchCB
Added link

[mb018538]

15 minutes ago, I remember Atlantic 252 said:

dumb question too, but what does the x mean on FAX? seems to be over my area

 

I think they mark the point at which the central pressure of a particular cyclone/anticyclone is at its low/high point. Ie for a low pressure the lowest pressure point, and for high pressure the spot with the highest pressure. Someone please correct me if wrong!

[Captain Shortwave]

28 minutes ago, minus10 said:

Captain, sorry if this is a dumb question but which part of Meteociel do you get those prec charts for the uk as i cant locate them..many thanks.

Instead of selecting the GFS operational, chose the GFS 0.25 option that is right below the other option on the sidebar. Then you will get a series of options including temperature, rain for a particular time and of course accumulated rainfall from the start of the run. You can select the specific European country you want to look at.

[minus10]

27 minutes ago, Captain Shortwave said:

Instead of selecting the GFS operational, chose the GFS 0.25 option that is right below the other option on the sidebar. Then you will get a series of options including temperature, rain for a particular time and of course accumulated rainfall from the start of the run. You can select the specific European country you want to look at.

Great...got it...thanks

[MATTWOLVES 3]

Again there is strong support from the 12z mean of building Heights later next week...infact this trend could hold firm right through the Bank Holiday...I appreciate that it's a long way off,but the way this Summer as panned out I certainly wouldn't bet against it!

Hopefully this High will influence further North with time and it does look like less in the way of low Heights even further North with time 

My final thoughts this evening to sum up.

1..Its Hot and sunny this weekend.

2..Next week starts very warm and humid with an increasing risk of showers...amounts and areas tbc.

3..We gradually rebuild Heights later next week/Weekend and this trend potentially holding firm right through til the Bank Holiday...hopefully throughout it.

Whatever your poison enjoy it wisely  

Edited August 12, 2022 by MATTWOLVES

[JayAlmeida]

¡Ola Senor Azore! 

[MATTWOLVES 3]

7 minutes ago, JayAlmeida said:

¡Ola Senor Azore! 

Hello sir!!  

Not a bad Noaa chart I have to say. Flow looks a little Wstly if I'm correct?

Edited August 12, 2022 by MATTWOLVES

[damianslaw]

It's a broadly westerly flow as we move through next week. Meaning cooler and wetter further north, drier and warmer further south. Much more typical August fayre than currently. 

[JayAlmeida]

18 minutes ago, MATTWOLVES said:

Hello sir!!  

Not a bad Noaa chart I have to say. Flow looks a little Wstly if I'm correct?

Its progress after the troughy 6-10 day charts being thrown up over the past few days.

I think that chart sets things up quite nicely for the final week of August. I know the south is parched but I for one would like to go out with a bang and not a whimper this summer.

Getting used to this weather now.

Hopefully we can conjure up some rain for the SE between now and then.

Edited August 12, 2022 by JayAlmeida

[stodge]

I'm also struck by the continued lack of tropical activity and the impact that may have as we move into September, traditionally the heart of hurricane season.

I'm told this is due to high dust levels coming off the Sahara suppressing convective activity.

We know the path of these storms can cause the Azores HP to respond (often favourably and that's how we can get our decent autumns and "Indian Summers") but if we're in for a much quieter hurricane season, my presumption would be the cooling to the north would create a more traditional Atlantic flow and bring a cooler, wetter and windier start to autumn than other years.

[Paul]

1 hour ago, FetchCB said:

That's because each member is started with slightly different parameters to allow for the fact that initial observations are not statistically perfect 

Ensemble forecasting - Wikipedia

EN.M.WIKIPEDIA.ORG

 

It's not just that. The GFS is run at 0.25 degrees, and the gefs is run at 1 degree. So for surface based parameters in particular, it's a bit like comparing apples and oranges.

[damianslaw]

1 minute ago, stodge said:

I'm also struck by the continued lack of tropical activity and the impact that may have as we move into September, traditionally the heart of hurricane season.

I'm told this is due to high dust levels coming off the Sahara suppressing convective activity.

We know the path of these storms can cause the Azores HP to respond (often favourably and that's how we can get our decent autumns and "Indian Summers") but if we're in for a much quieter hurricane season, my presumption would be the cooling to the north would create a more traditional Atlantic flow and bring a cooler, wetter and windier start to autumn than other years.

Quite possibly. We've had a number of active seasons recently and generally quiet and warm settled Septembers. Might this September buck the trend and deliver a cooler Atlantic outlook. Take note of temps and polar cooling to our NW over next 2 weeks..

[MP-R]

30 minutes ago, stodge said:

I'm also struck by the continued lack of tropical activity and the impact that may have as we move into September, traditionally the heart of hurricane season.

I'm told this is due to high dust levels coming off the Sahara suppressing convective activity.

We know the path of these storms can cause the Azores HP to respond (often favourably and that's how we can get our decent autumns and "Indian Summers") but if we're in for a much quieter hurricane season, my presumption would be the cooling to the north would create a more traditional Atlantic flow and bring a cooler, wetter and windier start to autumn than other years.

Indeed. The more active seasons often bring us our settled Septembers and inject plenty of late warmth our way even well into October. Although even that’s not always the case E.g. Ex Hurricane Katia in 2011.

Climatologically though one would expect things to deteriorate as the month wears on. I often think if the 1st and 2nd thirds of September 2019 swapped around, you’d have ended up with a fairly typical September there.

Edited August 12, 2022 by MP-R
Spelling

[MattStoke]

GFS 18z has a lot of warmth next week besides a cool down mid week where it’s still warm in the south.

[Cheshire Freeze]

10 minutes ago, MattStoke said:

GFS 18z has a lot of warmth next week besides a cool down mid week where it’s still warm in the south.

This is more like it Matt...the first 0c uppers of the coming season

[MattStoke]

3 hours ago, CreweCold said:

This is more like it Matt...the first 0c uppers of the coming season

A few months too early for my liking

I’d have heat with occasional thunderstorms from May to October and cold with frequent snow from November to April if I could choose the weather. Think I lived in a continental climate in a previous life.

The GFS 0z is another very warm run for many besides mid next week where it turns cooler for a couple of days but still some warmth in the south.

UKMO less settled and cooler, though, with low pressure to the north west having more influence and the Azores high further south.

Edited August 13, 2022 by MattStoke

[seb]

Wow that GFS 0z never really gets rid of the heat. Bit cooler Wednesday, back to 25 Thursday slowly increasing and then by the following Wednesday we are back to 30. We then keep 31-32 to the end of the run.

As for rain - forget about it. All but gone from the large majority of England at less than 10mm by the end of the run.

Edited August 13, 2022 by seb

[mb018538]

33 minutes ago, seb said:

Wow that GFS 0z never really gets rid of the heat. Bit cooler Wednesday, back to 25 Thursday slowly increasing and then by the following Wednesday we are back to 30. We then keep 31-32 to the end of the run.

As for rain - forget about it. All but gone from the large majority of England at less than 10mm by the end of the run.

For some areas the rain on Monday and Tuesday from storms is about all that falls in the entire run. Places that miss these look like staying fairly dry for even longer.

[I remember Atlantic 252]

55 minutes ago, seb said:

Wow that GFS 0z never really gets rid of the heat. Bit cooler Wednesday, back to 25 Thursday slowly increasing and then by the following Wednesday we are back to 30. We then keep 31-32 to the end of the run.

As for rain - forget about it. All but gone from the large majority of England at less than 10mm by the end of the run.

Don't find it too bad! 26 Monday, 23 Tues and then early 20's rest of week, turns ugly in FI though with 30 degrees again

[MattStoke]

1 minute ago, I remember Atlantic 252 said:

Don't find it too bad! 26 Monday, 23 Tues and then early 20's rest of week, turns ugly in FI though with 30 degrees again

More standard summer warmth.

UKMO looks cooler and more unsettled, though, and ECM kind of looks in the middle of the two.

[Mark Smithy]

The 0z ECM is a pretty decently wet run throughout. Looking good for the parched south. Some sample screenprints:

 

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.

Edited August 13, 2022 by Mark Smithy

[seb]

25 minutes ago, I remember Atlantic 252 said:

Don't find it too bad! 26 Monday, 23 Tues and then early 20's rest of week, turns ugly in FI though with 30 degrees again

Your area yes. Down South there’s only two days below 25.

[MattStoke]

3 minutes ago, seb said:

The mean almost entirely follows the op apart from two minor spikes in rainfall, one of them in deep FI.

The latest ECM is very close to what the GFS Op is showing.

I really do not understand what you’re trying to achieve. All you’re doing is reducing your credibility.

It’s impossible to tell if the op is a ‘dry outlier’ anyway on that chart. The majority of runs could show nothing, in which case, the lines would overlap but only the op line would be visible on top of the others.

Edited August 13, 2022 by MattStoke

[Mark Smithy]

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

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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...

 

 

 

 

[seb]

3 minutes ago, Mark Smithy said:

The 0z ECM is a pretty decently wet run throughout. Looking good for the parched south. Some sample screenprints:

 

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.

 

3 minutes ago, Mark Smithy said:

The 0z ECM is a pretty decently wet run throughout. Looking good for the parched south. Some sample screenprints:

 

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.

No. Just no.

GFS vs ECM accumulated rain amounts by Wed 18z below. Barely a difference. 10mm or thereabouts over three days is a wet run? Sure. You are aware that we need 150% of average rainfall between 1 Aug and 31 March to end drought conditions I hope.