Model Output Discussion - Into Summer 2020.

[Man With Beard]

I've just realised there is also an ECM parallel ensemble mean!!

Comparing the existing ensembles with the parallel ensembles at D7:

  

and then D9

  

far less amplification towards Scandi on the new parallel ensembles, and as a result, not as hot.

Will be interesting to track the progress of the two for next week.

[Frosty.]

I’m liking the ECM 0z operational....and I’m sure I’m not alone!..low 30’s c? further s / se if this verifies!!!

 

Edited June 16, 2020 by JON SNOW

[Man With Beard]

8 minutes ago, JON SNOW said:

I’m liking the ECM 0z operational....and I’m sure I’m not alone!..low 30’s c? further s / se if this verifies!!!

 

Raw temperatures on the ECM op of 31C next Wednesday ... as we know, that is normally an underestimate of 1.5C to 3C. 

Worth noting that only 5 from 51 ensembles are as hot as this.

 

[Tamara]

On 14/06/2020 at 15:34, Tamara said:

Musing here to an extent, but for what it is worth, should the tropical signal align further c/o that anomalous warmth in the tropics and the polar cell remain stable - irrespective of what extended ensembles and associated cluster data suggests currently as a snapshot in time (yes, that phrase again) -  look for that trough to the NW to start align itself in such a way to allow some hot and potentially thundery conditions from the south later this month

NWP duly investigating the possibilities suggested in the previous summary.

Its the same story as detailed over the past 10 days - the requirement for tropical support to supply sub tropical ridge extensions to mid latitude and most especially to attain the eastward displaced Azores ridge that allows the sort of advection processes from the south envisaged in that previous post. There continues to a signal for a cyclical re-bound in angular momentum, irrespective of the long term trend - the question is where the floor is and where it can re-bound to - based on the extent to which angular momentum has fallen already.

Atmospheric angular momentum now reflecting a distinctly Nina-esque forcing on the atmosphere with the Global Wind Oscillation into a higher amplitude Phase 1 - based on the standard two day consolidated lag.

This represents this weeks synoptic pattern of an Atlantic ridge and slack low-ish heights across much of NW and central Europe. There is fortunately no polar cell forcing on the pattern c/o the mercurial and rather a-typical very weak e/QBO signature - hence the slack pattern is of the warm variety with a pleasing mix of lovely summer sunshine and convective enthusiasm.

Set against the suppressed momentum, as repeated previously, there is off-equator forcing strengthening the Azores sub tropical ridging, along with the lid being kept the on e/QBO stratospheric/tropospheric forcing and is preventing an authentic summer low angular momentum response which would involve a more pronounced Atlantic/Greenland ridge and a trough stuck across NW Europe and Scandinavia. On that basis there would no chance of any eastward ridge extension splitting to a downstream ridge element and allow, at least the possibility of a plume or very warm advection from the south - the predominant source of air would be from North Atlantic polar maritime and arctic maritime sources.

It is interesting that the EC seasonal model suggested the traditional Nina summer pattern for July - as initialised at the start of this month. However the EC weekly updates have moved in the opposite direction and along with the CFS modelling have reasonable agreement for anomalous ridging to persist across Scandinavia - with trough influence ebbing and flowing to the west. This does reflect quite significant differences in QBO and associated tropical forcing expectations.

The last two summers have shown it is possible to arrive at hot continental solutions under falling angular momentum in June - the key is maintaining influence from the tropics and attendant sub tropical ridging alongside the AO staying at least neutral.

What will matter, ultimately, is with the arrival of July and how the atmosphere couples with high summer wavelengths. That will decide whether the CFS/EC weekly modelling is accurate or, should momentum stay supressed and the polar cell start to become less favourable, the seasonal modelling is closer to what happens.

 

Edited June 16, 2020 by Tamara

[Leo97t]

Im really not sold on any particular outcome yet but it think the ECM Mean is along the right lines with a Azores building in temporarily. I really don't see much support for a plume, no model mean has yet to show this and would require the low to dig further south and east which again has yet to be modelled. I would hold off calling any hot weather for next week until at least Friday 

[northwestsnow]

GFS less aggressive with the low ..most precipitation reserved for the far NW so for   the majority things drying out nicely as we go through the weekend and temps climbing again through next week..

Good news for those who enjoy the outdoors for walking  fishing golfing ect.....

Edited June 16, 2020 by northwestsnow

[viking_smb]

1 minute ago, northwestsnow said:

GFS less aggressive with the low ..most precipitation reserved for the far NW so for   the majority things drying out nicely as we go through the weekend and temps climbing again through next week..

Good news for those who enjoy the outdoors for walking  fishing golfing ect.....

+ Sailing

[mb018538]

Both of these outcomes look warm to hot at day 8, more so in the SE.

[Neil Harris]

Hi, can anybody help with the models for thursday an in particular the timings/amounts of the rain.

BBC app and Netweather are showing 2 very different forecasts?

Thanks

 

[northwestsnow]

Yes the EC clusters look very good for an injection of warmth through next week...

[MATTWOLVES 3]

18 minutes ago, northwestsnow said:

GFS less aggressive with the low ..most precipitation reserved for the far NW so for   the majority things drying out nicely as we go through the weekend and temps climbing again through next week..

Good news for those who enjoy the outdoors for walking  fishing golfing ect.....

Perfect mate... I agree the 6z looks rather spiffing as we move into next week. Every time I hire a sunbed the weather improves...My holiday got cancelled and someone said if you can't go to the Mediterranean, then bring it to you.. Great for outdoor activities though... Enjoy mate. 

Ps.. Thanks for the latest thoughts Tams..

[Guest]

ECM clusters look more promising dont they. Switching to the GFS 06Z run, well its pretty ordinary on the surface of it and certainly seems to be moving away from a really warm spell to decent few days before again the door to the north west opens once again, again the ridge following the low pressure doesn't built in strongly enough with an increasingly strong and dominant Azores high.

[mb018538]

12 minutes ago, Alderc said:

ECM clusters look more promising dont they. Switching to the GFS 06Z run, well its pretty ordinary on the surface of it and certainly seems to be moving away from a really warm spell to decent few days before again the door to the north west opens once again, again the ridge following the low pressure doesn't built in strongly enough with an increasingly strong and dominant Azores high.

This little dip in heights is just preventing a full build in pressure. So despite SLP being high, there’s an upper trough in play. 

 

Also there on the ECM:

[northwestsnow]

3 minutes ago, mb018538 said:

This little dip in heights is just preventing a full build in pressure. So despite SLP being high, there’s an upper trough in play. 

 

Also there on the ECM:

Yep, as discussed, the more SE you head,the warmer and sunnier it should be...

Warm to hot Midlands south, then cooler and a bit wetter the further NW you head sounds reasonable.

6z has temps low 20s to high 20s manchester southwards right through next week.Could be better, could be worse i suppose.

[mushymanrob]

Whatever way you look at it, these charts are not supportative of a pressure build (for more then a transitory spell) off the Azores high and retains that well to the West with troughing the dominant feature. A NW/SE bias weatherwise with the coolest, wettest, cloudiest breeziest conditions in the Northwest. Quite pleasant in the southeast.

 

[Singularity]

Regarding those 6-10 day charts, the trough in the Atlantic is very anomalously large and deep during the first two days of that period, so it imprints strongly on the 5-day mean. There's then a strong consensus for the trough to weaken, allowing high pressure to become more influential across the UK for at least a couple of days. Most so southern parts - excepting a possible heat low involvement by day 9.

So while that assessment above is right in some aspects, it's not correct to interpret it as an indicator that the more settled spell will be short-lived.

The CPC 8-14 day illustrates a fine balance between sustaining settled weather and destabilisation from the west:

Could go either way. How much AAM climbs may have some influence on how long the ridge sticks around before a breakdown (and this will lead the model trends, not the other way around). The greater impact, though, will be on the propensity for ridges to build back in soon after the breakdown (however soon that occurs), the pattern reloading in classic summer fashion.

This being what Tamara informatively discussed earlier .

[mushymanrob]

21 minutes ago, Singularity said:

Regarding those 6-10 day charts, the trough in the Atlantic is very anomalously large and deep during the first two days of that period, so it imprints strongly on the 5-day mean. There's then a strong consensus for the trough to weaken, allowing high pressure to become more influential across the UK for at least a couple of days. Most so southern parts - excepting a possible heat low involvement by day 9.

So while that assessment above is right in some aspects, it's not correct to interpret it as an indicator that the more settled spell will be short-lived.

The CPC 8-14 day illustrates a fine balance between sustaining settled weather and destabilisation from the west:

Could go either way. How much AAM climbs may have some influence on how long the ridge sticks around before a breakdown (and this will lead the model trends, not the other way around). The greater impact, though, will be on the propensity for ridges to build back in soon after the breakdown (however soon that occurs), the pattern reloading in classic summer fashion.

This being what Tamara informatively discussed earlier .

Fair point, and i fully am on board with the 8-14 dayer "improving" conditions. There are imho reasons to be optimistic towards the end of the month.

[MATTWOLVES 3]

Alls well that ends well.. Well the UKMO ends well so no real complaints from Moir..

[Leo97t]

Just now, MATT said:

Alls well that ends well.. Well the UKMO ends well so no real complaints from Moir..

I don't agree its been continually pushed back - looking like a non event across the board on current output - not surprised by lack of comments

[Djdazzle]

The UKMO 144 is a very good chart which would develop well from there. ICON 12z is a very good run too.

[Leo97t]

its no doubt turning more settled but doesn't look good in the north as it was a few days ago

[Djdazzle]

3 minutes ago, Leo97t said:

I don't agree its been continually pushed back - looking like a non event across the board on current output - not surprised by lack of comments

GFS 12z 168 is hardly a non-event!

 

[MATTWOLVES 3]

Just now, Leo97t said:

I don't agree its been continually pushed back - looking like a non event across the board on current output - not surprised by lack of comments

GFS also improving things by day 6 or 7, around a similar timeframe..A warmer more settled spell through next next before perhaps conditions turning somewhat more unsettled again later next week. Pretty much what Exeter are implying.. Not to say they are correct or any of these models are.. And it makes no difference whether its quite on here... Sometimes when it's packed because the models are looking  good, it can still and very often does go wrong. 

[northwestsnow]

Excellent trends continue ...

Brief Atlantic incursion then high pressure nudging the low north..

Next week could be very warm across southern UK ...

[Leo97t]

6 minutes ago, Djdazzle said:

GFS 12z 168 is hardly a non-event!

 

All I'm saying is this is still in FI in my opinion. People should not be expecting a heatwave but rather a couple warmer days in the SE - setups like this always correct east and when you get a heatwave appearing on models you normally get perfect synoptic simulated before some small downgrades. I hope I am wrong but I just don't see it yet confidently