Model Output Discussion - Into Summer 2020.

[carinthian]

Morning all, think ECM charts this morning show reasons to be cheerful  for the start of next month. The Geopotential anom chart at 500mb height level (below) shows an anticyclonic weather pattern to influence the British Isles , especially dominant in the southern half with the Northern half more under the influence of a fairly weak maritime cyclonic flow . So this week looks like hotting up before cooler flow pushes in from the Atlantic towards weekend  and then fingers crossed for some fine weather to start the new month. Still cold and miserable out here under the upper low circulation, would you believe 5 c now with heating on ! Hopefully, some warm up later this week in the Eastern Alps. Enjoy your Sunday.

C

Edited June 21, 2020 by carinthian

[sheikhy]

Last nights 18z run had breakdown incoming from thursday afternoon with thunderstorms across england!!seems to have been pushed back on the 06z and 00z!!

[Allseasons-Si]

And what is the gfs up to,it produces a cut off low at just 96....

and hence produces this at 120 with that cut off low heading SE in to Iberia and this in turn prolonging the heat into the UK.

144,that low to the NW is getting deflected further north away from the UK,could be a good run this.

06z 144 v's 00z 150

 

Edited June 21, 2020 by Allseasons-si

[I remember Atlantic 252]

8 minutes ago, sheikhy said:

Last nights 18z run had breakdown incoming from thursday afternoon with thunderstorms across england!!seems to have been pushed back on the 06z and 00z!!

Aye, low much further west

[MATTWOLVES 3]

The ECM mean is pretty good tbh.. We have a minor breakdown before the High ridges in from the SW again.. Pressure looks fairly consistent to around 1020mb come the end of the run. Certainly know prolonged unsettled spell.. Ohh and plenty of heat this coming week.. Enjoy.

[Tamara]

1 hour ago, mushymanrob said:

Pure speculation here, but when these contour lines are "flat" they seldom stay flat for very long, maybe a few days.
Then theyll buckle, and show a forming ridge/trough pattern. This happened last August, and the ridge evolved into the Bank Holiday heatwave.
If you have faith in the accuracy of these charts (when consistent) then you can IMHO take a speculative punt on the direction they are heading beyond the 14 day current limit, based on past pattern evolutions. Given that, after a period of normal average unsettled westerly based weather following the breakdown of this weeks heat, the next ridging/warm spell could be here (or near) by the end of week 1 in July.
I doubt whether many would agree with this (looking at you @johnholmes lol) but hey, we will see ... nothing to lose and trying to understand the complexities is fun!

 

What is always helpful with these anomaly charts is that its possible to see very easily via the contour lines where any amplification across the hemisphere as a whole is occurring and where the converse response is found - having filtered out the usual operational and intra day noise and distraction most especially of operational NWP.

This is where the wind-flow diagnostic can be matched up to the upper air pattern to discern how NWP interprets how the upstream pattern dictates what happens downstream. Rising angular momentum tendency c/o rossby wave transfer in the tropics to the extra tropics alters the amplification wavelength from upstream further downstream  and vice versa if momentum falls upstream - so the type of example @mushymanrob cites is where an increase in momentum has created the downstream buckle - the downstream response to the upstream pattern doing the reverse and flattening out some. This is clearly an extremely simplified and somewhat dumbed down overview of the complex processes involved but I found its not a bad starting point to getting to understand wind-flow inertia and torque mechanisms (the turning force applied to the jet-stream) as a visual to get in your mind.

There are some differences emerging between how the GFS and its ensembles and the EPS are modelling the polar field profile - with the result that the former wants to supress the jet stream at our mid latitude more than the former. This is one of the pitfalls I was referring to the other day - there was a period in late May when some NWP tried to invoke a more -AO pattern but did an about turn. This related more especially to the GFS  (correctly) identifying falling angular momentum into early June - but taking this a step further with some summer 2007 style stratospheric downwelling of negative zonal winds into the troposphere.

With the QBO stalled once more, and continued very enigmatic behaviour of this easterly transition then a lot of caution has to be attached to any modelling trying to build heights across the arctic and parking supressed trains of lows across the Atlantic across the UK and into Europe. There has been considerable long term lagged feedback  due to the remarkably intense positive AO signature of last winter in addition, - so this makes the more traditional high pressure to the south and lower pressure to the north more intuitively probable. Much as these summaries have continued to suggest in recent weeks.

 Tropical modelling c/o the velocity potential anomalies continues to show transition of the convective response to the Indian Ocean progressing through the summer, so there is little doubt that angular momentum trends will be (overall) negatively influenced.  Note the orange supressed signal close to the dateline further developing through July and replacing the standing wave convective signal (shaded blue)that has been evident for quite some considerable time

 

The second half of the summer holds uncertainties based on this outlook in terms of implications for changed propagation of wind-flow inertia between the tropics and extra tropics.. However as long as the polar profile remains stable, then some of the commentary this morning is very reasonable - a changeable outlook, but for the time-being at least continued room for further shorter length fine warm spells as and when the upstream Pacific profile allows (i.e when it is least amplified).

In the meantime it is sensible advice to enjoy the stunning spell of outdoor weather to come this week. Deep blue skies and summer sunshine and lots of Vitamin D for well-being

 

Edited June 21, 2020 by Tamara

[Frosty.]

1 hour ago, mountain shadow said:

Very zonal looking charts this morning. 

Hmmmm..the next 5 days don’t look very zonal.,indeed zonal doesn’t compute for the next 5 days!!!! ergo, increasingly hot and sunny continental conditions with an increasing chance of thunderstorms later, especially into next weekend!!!..as Tamara says, stunning spell!

Edited June 21, 2020 by JON SNOW

[swfc]

I've never understood the liking for very high temps etc esp when at workAnyway looking at some comments recently I noticed there seems to a belief the Oz runs are not as accurate as the later ones???is there any proof of that or is it just because they don't show what folk want?Tia 

[johnholmes]

1 hour ago, mushymanrob said:

Pure speculation here, but when these contour lines are "flat" they seldom stay flat for very long, maybe a few days.
Then theyll buckle, and show a forming ridge/trough pattern. This happened last August, and the ridge evolved into the Bank Holiday heatwave.
If you have faith in the accuracy of these charts (when consistent) then you can IMHO take a speculative punt on the direction they are heading beyond the 14 day current limit, based on past pattern evolutions. Given that, after a period of normal average unsettled westerly based weather following the breakdown of this weeks heat, the next ridging/warm spell could be here (or near) by the end of week 1 in July.
I doubt whether many would agree with this (looking at you @johnholmes lol) but hey, we will see ... nothing to lose and trying to understand the complexities is fun!

 

Yes I agree mushy it is fun speculating using these charts. One or two seem to use them rather too simply in my view buet hey ho who am I to complain. No idea beyond 14 days what may happen mushy but just been looking at the morning output from GFS and ECMWF, and, pretty much, like the NOAA chart you show, they, currently do not suggest anything other than a reasonably gentle Atlantic flow. I suppose we must look further back to teleconnections to see if they are also giving a consistent pattern prediction for what the anomaly charts may come up with over the next 5-7 days. For sure at the moment, in my humble opinion, they suggest no major heat or ridging low or high level for 7-12/14 days. 

Beyond 10-14 days its, as some say on here, beyond my pay grade, perhaps more accurately beyond my brain level these days!

[Man With Beard]

ECM clusters show this is not done and dusted - looks to me on cluster 1 (this is Monday week) that the Atlantic front has struggled to get through the UK a lot more than this morning's op runs have (except GFS 6Z), it's a lot more like the ECM runs of the previous 2 days:

[johnholmes]

3 minutes ago, johnholmes said:

Yes I agree mushy it is fun speculating using these charts. One or two seem to use them rather too simply in my view buet hey ho who am I to complain. No idea beyond 14 days what may happen mushy but just been looking at the morning output from GFS and ECMWF, and, pretty much, like the NOAA chart you show, they, currently do not suggest anything other than a reasonably gentle Atlantic flow. I suppose we must look further back to teleconnections to see if they are also giving a consistent pattern prediction for what the anomaly charts may come up with over the next 5-7 days. For sure at the moment, in my humble opinion, they suggest no major heat or ridging low or high level for 7-12/14 days. 

Beyond 10-14 days its, as some say on here, beyond my pay grade, perhaps more accurately beyond my brain level these days!

Just noticed after I posted T has given a view on how the link may be used. Fascinating all this to an ex forecaster where, when I started, using the 300 mb actual chart and when they came along a few years later the computer's 300 mb predicted chart for 48-72 hours. My how we have advanced. Be good to able to 'come back' in another 50 years or so and see where we are with the science of meteorology?

Edited June 21, 2020 by johnholmes
spelling

[MATTWOLVES 3]

9 minutes ago, johnholmes said:

Just noticed after I posted T has given a view on how the link may be used. Fascinating all this to an ex forecaster where, when I started, using the 300 mb actual chart and when they came along a few years later the computer's 300 mb predicted chart for 48-72 hours. My how we have advanced. Be good to able to 'come back' in another 50 years or so and see where we are with the science of meteorology?

You must be on a good multivitamin John.. I will see you in another 50 years for a review... Excellent stuff..

[Djdazzle]

17 minutes ago, swfc said:

I've never understood the liking for very high temps etc esp when at workAnyway looking at some comments recently I noticed there seems to a belief the Oz runs are not as accurate as the later ones???is there any proof of that or is it just because they don't show what folk want?Tia 

From years of model watching, it just seems that the 00z are generally more progressive. Maybe the 12z are less so, with the reality being somewhere in between.

[Captain Shortwave]

That low at the end of the week is still causing a headache. There are two routes;

1) The low remains a shallow wave and drops into the weak trough west of Iberia, like the GFS run just gone. This produces a slower and more thundery breakdown as low pressure moves up from France thanks to this trough.

2) The low is slower and further north, this engages the broad trough and deepens, a simple breakdown from the west with a front pushing east ushering in cooler air by the weekend. Either one or two still develops this low as the following one joins the main Atlantic trough regardless.

Beyond this, actually the deep low forming next weekend appears to be the most threatening item in the coming two weeks, the Azores high looks to stretch across much of Southern Europe and will periodically influence the weather for the UK, especially southern areas.

Edited June 21, 2020 by Captain Shortwave

[summer blizzard]

Euro this morning is more unsettled than 48 hours ago however probably more pleasing for those of us wanting some severe weather with this breakdown. To start with the Euro has pushed the core of the heat to Weds/Thurs now (though we might also squeeze out 30C in the south on Friday) but critically on Friday it lowers pressure and has a trough move through on Saturday ahead of the main front on Sunday (judging by the 500 and 850 charts. This suggests that those in the south and south east especially could have a lot of fun. The main front should also be reasonably active although its all over by Sunday aside from perhaps the south east squeezing out another 25C day. 

GFS6z is a little different in that it models cooler uppers (probably only Friday would hit 30C) and slows the low pressure at the weekend but is broadly similar bar squeezing out the extra 25C day next Monday. Tues-Thurs we see broadly clear skies (perhaps some showers breaking out in the west on Thursday) before we see more convective action on Friday and Saturday.

Edited June 21, 2020 by summer blizzard

[mountain shadow]

36 minutes ago, JON SNOW said:

Hmmmm..the next 5 days don’t look very zonal.,indeed zonal doesn’t compute for the next 5 days!!!! ergo, increasingly hot and sunny continental conditions with an increasing chance of thunderstorms later, especially into next weekend!!!..as Tamara says, stunning spell!

I meant in the extended.

Little chance of hot sunny continental conditions in the North West.

[Guest]

49 minutes ago, swfc said:

I've never understood the liking for very high temps etc esp when at workAnyway looking at some comments recently I noticed there seems to a belief the Oz runs are not as accurate as the later ones???is there any proof of that or is it just because they don't show what folk want?Tia 

I've never understood anyone liking and looking for cold and snow in Winter but we are all different. Personally I would much rather take a lunch break and sit on the balcony at work if its 30c than 20c.....

Things far from resolved at the end of the week, the 00Z had maxes of 18C here on Saturday and the full backing on the ensembles, the 06Z is some 6-7C warmer so a positive step forward!! 

Edited June 21, 2020 by Guest

[MP-R]

46 minutes ago, swfc said:

I've never understood the liking for very high temps etc esp when at workAnyway looking at some comments recently I noticed there seems to a belief the Oz runs are not as accurate as the later ones???is there any proof of that or is it just because they don't show what folk want?Tia 

With you on that. This week looks great, but I'll get excited when the sun and heat is progged for the weekend. Maybe with the help of a cut off low, that could be possible.

[joggs]

1 hour ago, Tamara said:

What is always helpful with these anomaly charts is that its possible to see very easily via the contour lines where any amplification across the hemisphere as a whole is occurring and where the converse response is found - having filtered out the usual operational and intra day noise and distraction most especially of operational NWP.

This is where the wind-flow diagnostic can be matched up to the upper air pattern to discern how NWP interprets how the upstream pattern dictates what happens downstream. Rising angular momentum tendency c/o rossby wave transfer in the tropics to the extra tropics alters the amplification wavelength from upstream further downstream  and vice versa if momentum falls upstream - so the type of example @mushymanrob cites is where an increase in momentum has created the downstream buckle - the downstream response to the upstream pattern doing the reverse and flattening out some. This is clearly an extremely simplified and somewhat dumbed down overview of the complex processes involved but I found its not a bad starting point to getting to understand wind-flow inertia and torque mechanisms (the turning force applied to the jet-stream) as a visual to get in your mind.

There are some differences emerging between how the GFS and its ensembles and the EPS are modelling the polar field profile - with the result that the former wants to supress the jet stream at our mid latitude more than the former. This is one of the pitfalls I was referring to the other day - there was a period in late May when some NWP tried to invoke a more -AO pattern but did an about turn. This related more especially to the GFS  (correctly) identifying falling angular momentum into early June - but taking this a step further with some summer 2007 style stratospheric downwelling of negative zonal winds into the troposphere.

With the QBO stalled once more, and continued very enigmatic behaviour of this easterly transition then a lot of caution has to be attached to any modelling trying to build heights across the arctic and parking supressed trains of lows across the Atlantic across the UK and into Europe. There has been considerable long term lagged feedback  due to the remarkably intense positive AO signature of last winter in addition, - so this makes the more traditional high pressure to the south and lower pressure to the north more intuitively probable. Much as these summaries have continued to suggest in recent weeks.

 Tropical modelling c/o the velocity potential anomalies continues to show transition of the convective response to the Indian Ocean progressing through the summer, so there is little doubt that angular momentum trends will be (overall) negatively influenced.  Note the orange supressed signal close to the dateline further developing through July and replacing the standing wave convective signal (shaded blue)that has been evident for quite some considerable time

 

The second half of the summer holds uncertainties based on this outlook in terms of implications for changed propagation of wind-flow inertia between the tropics and extra tropics.. However as long as the polar profile remains stable, then some of the commentary this morning is very reasonable - a changeable outlook, but for the time-being at least continued room for further shorter length fine warm spells as and when the upstream Pacific profile allows (i.e when it is least amplified).

In the meantime it is sensible advice to enjoy the stunning spell of outdoor weather to come this week. Deep blue skies and summer sunshine and lots of Vitamin D for well-being

 

As ever Tamara,brilliant to read your thoughts. Thankyou.

[Methuselah]

33 minutes ago, Alderc said:

I've never understood anyone liking and looking for cold and snow in Winter but we are all different. Personally I would much rather take a lunch break and sit on the balcony at work if its 30c than 20c.....

Things far from resolved at the end of the week, the 00Z had maxes of 18C here on Saturday and the full backing on the ensembles, the 06Z is some 6-7C warmer so a positive step forward!! 

I can't speak for everyone, of course, Chris... but, despite my not exactly 'enjoying' 32C Betty Swollocks weather (or, for that matter, being blitzed by driving snow in winter) I always get excited when things turn 'unusual' -- my trip to the Jobcentre, on March 1st 2018, for example, will live long in my memory: driving 'torrential' snow at -5C kinda does that!?

Now, though...a mega fantastic humongous thunderstorm will do me just fine!

[h2005__uk__]

The models suggest it'll be a bit of a knife-edge for certain places in the E/SE next week as to whether they'll tap into the highest temperatures. However, given maximums are often underestimated, it's probably more likely than it appears?!

[Methuselah]

An interesting GEFS T850 ensemble, I think; the mean and control really don't reflect a cataclysmic deterioration, sometime next weekend...Uppers of around 7C (mean) longer-term, will do me fine!

Edited June 21, 2020 by General Cluster

[sheikhy]

15 minutes ago, General Cluster said:

An interesting GEFS T850 ensemble, I think; the mean and control really don't reflect a cataclysmic deterioration, sometime next weekend...Uppers of around 7C (mean) longer-term, will do me fine!

Gfs has lost the plot between 27 and 30th!!no support what so ever!!expect it to bring us back to reality in a few hours!!!if it shows the same thing on the 12z then maybe it spotted a new trend but until then no chance!!!

[Gordon Webb]

2 hours ago, swfc said:

I've never understood the liking for very high temps etc esp when at workAnyway looking at some comments recently I noticed there seems to a belief the Oz runs are not as accurate as the later ones???is there any proof of that or is it just because they don't show what folk want?Tia 

you will  find its the latter

[Mike Poole]

3 hours ago, swfc said:

I've never understood the liking for very high temps etc esp when at workAnyway looking at some comments recently I noticed there seems to a belief the Oz runs are not as accurate as the later ones???is there any proof of that or is it just because they don't show what folk want?Tia 

There is no belief that the 0z runs are less accurate than the 12z ones.  The NH statistics for them show no statistically significant difference between them for sure.  The suspicion (and I've seen no proof for this, it is from experience watching the models) is that the 0z have a slight bias towards zonal weather for UK, and the 12z have a slight bias towards blocked patterns.  This could still be the case even if the NH stats are essentially the same.