Model output discussion - into July 2020

[northwestsnow]

EC follows the script above,a general drying out for the next 7 days or so before things start to go downhill.

Low to mid 20s for the south ,high teens Manchester sounds a decent stab.

July will likely fall into the rotten category locally, perhaps average in the SE.

April and May were fabulous,June and July,meh ...

Hopefully August will provide something more palatable..

[Guest]

Usual story at T144, weak high pressure ridging in from the south west, plenty of cloud & clag likely spilling up, over and down across the UK, maybe with the south east escaping with some briefly average to decent conditions but generally under the influence a deep cold pool for the time of year I really think temps will struggle.

Some of the jet forecasts, showing it ploughing down over southern France & Spain into the Med are concerning, we all know once that happens it becomes a tricky thing to shift and could spell trouble for the rest of summer. 

Seems like the rest of world is all ganged up on us currently, patterns in the Pacific not favourable, huge Arctic high and a massive heat dome over the US only getting stronger likely to add even more energy to the Jet.  

Edited July 16, 2020 by Guest

[Methuselah]

A pretty average-looking GFS 00Z run, this morning:

    

    

    

    

    

And the ens don't look to be too bad:

    

    

NH profiles:

    

    

So, something for everyone in there somewhere... And a veritable bonanza for the moaners!

[Frosty.]

Next week’s not looking too bad according to the ECM 0z ensemble mean, it shows some Azores ridge influence, mainly across southern u k..so, for the south at least there is a suggestion it could become more settled and warmer again (for a time) following a cooler / changeable blip..in the meantime, there’s some warmth and sunshine to enjoy further s / e during the next few days.much better than most of this week has been!

 

[summer blizzard]

Euro and GFS essentially in agreement that next week will be somewhat similar to this week however both models show the Azores High withdrawing by day 8 and a cyclonic output thereafter.

[mb018538]

No signs yet of any significant AAM rise on the ECM, with it only just recovering from off the negative scale today. 

Notice how the coloured dots of previous runs gradually sit below each other in the next week as the time moves on - so any rise in momentum is becoming less pronounced, and pushed further into the distance.

[Tamara]

1 hour ago, mb018538 said:

Not really - there have only been 3 named storms so far, and none of them have been strong at all. There are E Pacific storms every year, so by your logic that would make every single UK summer bad.

Pacific cyclones are a good thing for Western European summers - it demonstrates that the ENSO region is convectively active, trade winds reverse c/o the westerly wind bursts which accompany the thunderstorm and cyclone development and can help the downstream pattern reverse from what we are seeing this summer with a corresponding low pressure anomaly centred to the west in the Atlantic and a perpetuating downstream ridge which ebbs and flows over and to the east (in the same way in reverse that the default retracted Azores ridge is to the west this summer due to the opposite much less helpful configuration)  Hence, much more continental influence than we are seeing this summer and also thundery potential as the default Atlantic trough disrupts against the downstream ridge from time to time. Rinse and repeat in a very good way.

In the present however, with so much influence from the North Atlantic arcing around the perimeter of the retracted Azores/Atlantic ridge it is no surprise to see the cool and changeable pattern that has dominated and with the upper trough being constantly reinforced to the N and NE and preventing any continental influences. Also no surprise that, last week of June aside, thundery potential from plume scenarios has also dwindled to nothing.

The reality is that it was possible to see back in May that a traditional La Nina-esque type circulation might well develop and associated Atlantic ridge and downstream trough  - what couldn't be predicted was precisely where tropical convergence would arise and on that basis it was quite possible that a more blended pattern may have resulted. Indeed for a time this was actually the case as the late June mini heatwave demonstrated.

However,. the high frequency MJO tropical cycle has become very quiet since late Spring, and following the active cycles during Spring itself which generated the westerly inertia and sustained atmospheric angular momentum above average. More about the high frequency signal later into the post.

Frictional torque tendency has been buoyant as described in previous posts. However following what has transpired to be a brief westerly wind burst east of the dateline, and which if sustained would have helped the possible signs of improvement that were apparent up to recently, much of the inertia is now concentrated  south of the equator in the southern hemisphere and trade winds across the Pacific look set to see further quite strong phases through the second half of July

 

 

This will certainly serve to keep angular momentum below average and the Global Wind Oscillation spot welded in the low angular momentum  La Nina attractor phases. Notice the contrasting westerly wind anomalies at 30N prior to the start of summer driving the downstream anticyclonic wave-breaking and the switch to easterly inertia at 20N to 30N in recent weeks - switching to upstream amplification at the inflection point of the negative torque mechanism  - scrubbing all the westerly inertia from the system

 

.....and this in turn will perpetuate the upstream amplification and the downstream response to that of an Atlantic ridge and upper trough that keeps trending into Scandinavia.

NWP at present is showing some signs of e/QBO type stratospheric interference which up till now has kept at least the sub tropical ridge in play and prevent a sustained supressed jet stream sinking further south. On previous occasions the modelling, for reasons given back then, has rowed back on this development, so a watch is required as to how this plays out this time.

What could help alleviate or provide some respite from this disappointing pattern?

Signs of some activity from the high frequency MJO tropical signal propagating eastwards from the Indian ocean and at least temporarily acting "destructively" on the default walker circulation which is rooting the low frequency tropical signal across Africa and the Indian Ocean and which in turn is boosting all the easterly (trade wind) inertia across tropics and into the Pacific. It is this atmospheric chain that sets up the downstream responses that are so evident.

Also heading ultimately into the latter part of summer it could be that just a small recovery of momentum c/o of some MJO related activity allied to ex tropical activity curving around into the Atlantic may create some warm air advection to shake up the pattern - at least for a while. Even in default long term term regimes such as these, it is natural for there to be a "wane" phase. Low angular momentum summers quite often see this the further one heads into August and often September as well based on intra-seasonal factors that can drive these temporary changes before the ridge/trough regime returns into autumn. Though some will consider this too late, the reality though is there is a good 10 weeks or more where summer like temperatures are quite easily achievable with better synoptics.

I would recommend looking into the diagnostic element as described and at the whys and wherefores - understanding why patterns entrench themselves like this is a constructive antidote to the rather pointless and self harming processes of agitating and moaning about the weather outside the window and which should be in the appropriate thread anyway, if one has nothing better to do with their day

 

 

 

[johnholmes]

I suspect this may get some folk wound up but I have to agree, trying to be construvtive rather than the opposite is always the better way. Not easy I know but as T suggests looking why something has or not happened can be very constructive.

I would recommend looking into the diagnostic element as described and at the whys and wherefores - understanding why patterns entrench themselves like this is a constructive antidote to the rather pointless and self harming processes of agitating and moaning about the weather outside the window and which should be in the appropriate thread anyway, if one has nothing better to do with their day 

 

[Frosty.]

Firstly, awesome post from Tamara as always!..secondly, I’m not seeing anything worse than sunshine and heavy, thundery showers even when there is a trough parked over the u k..which I actually like!!!!..however, there’s plenty of ridging for most of next week indicated, especially across the south, so it’s certainly not the doom and gloom that some would have you believe!

[mb018538]

Thanks @Tamara, great post as usual.



With the MJO passing over equatorial Africa in the next week or so, we should see some enhancement in the easterly waves as -ve VP passes over the favourable region.
Perhaps if we keep an eye on the Atlantic basin in the next fortnight we might see a storm or two spin up and shake the tree a bit. If nothing comes of that then it looks completely dead going into August as +ve VP takes control.
 

[Frosty.]

Would it be fair to call the Gfs 6z operational a mixed bag?..well that’s what I think!!!..in a nutshell it’s a predominantly north / south split for most of next week with the best of the fine and warmer weather further south due to Azores ridging but further ahead it’s more troughy with a mixture of sunshine and showers, some heavy and thundery, always warmest further SE, progressively cooler further NW.. it’s all fairly typical u k summer weather where the N / NW gets the muddy / Shi**y end of the stick.

Edited July 16, 2020 by JON SNOW

[Zak M]

06z GFS ensembles showing perhaps a bit of a warm up at the end of next week?

[Mark wheeler]

Today’s Ukmo 144 hrs . Settled but no heat . 

[Mark wheeler]

Gfs at the same time frame . 

[Mr Frost]

Afternoon all! 

Lovely weather today for some - can’t argue with that if you live in some of these places.  (NE/E Scotland included)

Tomorrow looks very toasty down South!

UKV:

 

Further into the weekend the GFS brings a cooler day for many - Summer has retreated back to France again. 

 

Start of the new week could bring some cool nights.

 

UKMO shows the usual stuff at 144 - mid teens up here and low twenties in the SE. 

 

So pretty much more of the same in the mid term - some will be happy and some will be disappointed! Plenty of Summer left to shake things up and deliver a UK and Ireland wide heatwave. (Please let it happen! )

All the best everyone and have a good weekend! 

[summer blizzard]

GFS to day 10 is similar to recent runs. 

Day 7 - Ridge begins to collapse

Day 8 - Fronts arrive in the west

Day 9 - Low Pressure firmly in control

[Zak M]

For once, the GFS shows a very good chart. Way into Fantasy Land though...

[NApplewhite]

1 hour ago, summer blizzard said:

GFS to day 10 is similar to recent runs. 

Day 7 - Ridge begins to collapse

Day 8 - Fronts arrive in the west

Day 9 - Low Pressure firmly in control

1st August 2020 looks hot 

[mb018538]

Were starting to see some model agreement of low pressure (depth and intensity to be resolved) paying us a visit next Friday/Saturday 

[Zak M]

Looks like the AH is trying to ridge in at the end of the 12z ECM

[Djdazzle]

3 minutes ago, Zak M said:

Looks like the AH is trying to ridge in at the end of the 12z ECM

Like it’s been trying all summer!

[mb018538]

12 minutes ago, Zak M said:

Looks like the AH is trying to ridge in at the end of the 12z ECM

Just another weak ridge I feel - southerly jet with Greenland heights. Storm track for the UK.

[Mark wheeler]

11 minutes ago, Djdazzle said:

Like it’s been trying all summer!

oh it will make it in come mid December don’t you worry about that .

Anyway Navgem tonight . I know it over does the uppers but god its so close on this run from the southeast . 

[Methuselah]

Nothing I've seen on today's charts seem all that bad... at least the Triptych of Doom (cold, wet and windy) is unlikely to be too much of a problem? In the meantime, tomorrow looks like being a cracker!

[MATTWOLVES 3]

While I wait for the EC46 to roll out just a quick glance at temperatures for Friday.. Looks like we could eek out a 27-28c in a few favoured spots, especially where sunshine is at a premium. 

The mean Is much the same, it trends more unsettled by next weekend before hints of a slight improvement come the end... Again i will know more in an hour or 2 if this will be backed up by the weeklies. 

Edited July 16, 2020 by MATT☀️
Adding charts.