Model Output Discussions 12z 01/06/2017

[Man With Beard]

September 1st, what do the clusters say?

No need to place any bets. A magical reappearance of strong heights over the UK, of course!

Year after year ... it's like clockwork

[cheshire snow]

49 minutes ago, Man With Beard said:

September 1st, what do the clusters say?

No need to place any bets. A magical reappearance of strong heights over the UK, of course!

Year after year ... it's like clockwork

Certainly is year after year has been glourios here long may it continue

C.S

[049balt]

Tamara, haven't heard from u in a while, have you any comments on prospects for September.

[Frosty.]

The Ecm 12z shows a glancing blow with low pressure for a time early next week, mainly affecting northern uk followed by a good recovery from midweek as high pressure gradually builds in across the uk with increasingly settled and warmer weather towards the end of next week, especially further south.

All being well, a fine end to august and start to september..high pressure would make a nice change!.

Edited August 24, 2017 by Frosty.

[ANYWEATHER]

Evening All  If you were to imagine a pool of water stir it very quickly and you get a disorganised ripple effect on the pool , this basically what happens when tropical developments stir up the jet stream at this time of year in the North Atlantic , computer models have no clue...... But this September beckons something very different from recent years

[summer blizzard]

1 hour ago, Frosty. said:

The Ecm 12z shows a glancing blow with low pressure for a time early next week, mainly affecting northern uk followed by a good recovery from midweek as high pressure gradually builds in across the uk with increasingly settled and warmer weather towards the end of next week, especially further south.

All being well, a fine end to august and start to september..high pressure would make a nice change!.

That's not what i'd call building over the UK, it tries to but retrogresses (dry but probably average).

[Frosty.]

The Ecm 00z turns into a beauty with high pressure becoming dominant, a summery end to summer and a very summery early autumn if this verifies. Today and the Bank Holiday weekend looks very respectable too, especially further south with warm temperatures and variable amounts of cloud and sunny spells, Monday could be very warm or hot across the SE with temps into the high 20's celsius. 

Edited August 25, 2017 by Frosty.

[mb018538]

I thought the BBC long ranger last night was a bit premature in stating that there wouldn't be any heatwave coming up. Now, it's not a certainty by any stretch, but it's not completely off the table, as the ECM shows this morning. More likely not to happen, but it's still a chance. Looking much better into the back end of next week. 

[Summer Sun]

ECM ends with +18 850's pushing into the south for the first day of the schools returning after the summer holidays

[Frosty.]

The Ecm 00z ensemble mean also shows high pressure building in through the second half of next week with increasingly warm and settled weather which continues into week 2. In the meantime, today and the Bank Holiday weekend indicate plenty of dry, warm and sunny weather with variable cloud, best of the sunshine for the south with temps widely into the low 20's c across southern uk and heading towards the mid 20's celsius for the s / se and next Monday temps look like climbing into the low 80's F across the s / se.

I'm optimistic about the outlook, more than I've been for some time.

Edited August 25, 2017 by Frosty.

[Man With Beard]

A lot of good runs on the ECM clusters by D10 - lots of good heights over the UK, in fact most better than the cluster that contains the op run. Heat levels would vary but all of the warmish side I'd suggest

September really loves us, doesn't it!

[Faronstream]

As always the high pressure finally moves up to northern europé in September instead of middle of july when we can get severe heat spells, i'm not complaining but i still don't understand why this pattern repeats itself for several years now

[stodge]

Afternoon all

GFS going in a very different direction on the 06Z OP:

The evolution into low-res screams autumn with deepening and increasingly vigorous LP systems to the NW and the Azores HP completely suppressed leaving us in a strong WSW'ly flow.

[Captain Shortwave]

It must be late summer, lots of tropical systems in the Atlantic and an absolute mess in terms of model output. 

Day 5 charts

UKMO/GFS/GEM

      

All seems to be dependent on the approaching Atlantic trough, the UKMO has this as an almost non-existent feature and zips a series of fronts east with the south and east ostly dry and warm, the GFS makes more of this trough and this interacts with the cold pool over Portugal which develops an area of low pressure to our south which brings heavy and thundery rain north eastwards, the UK mostly misses the heat. The GEM however has a full blown trough to our west and draws a south to south easterly flow during the first half of next week with temperatures rising towards the 30C mark.

The output after this still olds the same level of uncertainty, but the south looks pretty good with lots of warm and mostly dry weather, the north looks more mixed though.

[northwestsnow]

5 hours ago, Faronstream said:

As always the high pressure finally moves up to northern europé in September instead of middle of july when we can get severe heat spells, i'm not complaining but i still don't understand why this pattern repeats itself for several years now

It does seem to be a trend when following a poor summer,certainly in recent years although i do recall 1985 my first year in secondary school was a poor summer and a very warm september, the winter that followed would be welcomed by many on here-November in particular was cold and anticylonic as high pressure built over scandy-

Anyway, back to todays models and it does look like HP will take over as we eave August-

[Sky Full]

UKMO and ECM both have nothing sinister in the offing at +144, in fact both promise some benign conditions for most:

    

ECM and GEM not wanting to be quite so optimistic but neither are they showing any imminent return of strong Atlantic weather: 

    

Little sign of an early descent into Autumn yet, and possibly a return of some welcome summery conditions for a time at least.  Something of an improvement on the rest of August then, at least in my part of the world (but we can take it!  )

[Frosty.]

I would settle for the Ecm 12z T+168 chart thanks very much! It's going just like the 00z which is great to see!

Early September heat

Edited August 25, 2017 by Frosty.

[Summer Sun]

Nice to see ECM bringing back the warmth/heat as we move into Autumn

[Summer Sun]

Much closer time frame BH Monday could see 30c in the London area

[Frosty.]

Looking at the Ecm 12z day 10 chart, the coldie in me couldn't help noticing a very early taste of Northerly Arctic air being drawn south, not too far north of the uk...

[Captain Shortwave]

Not a bad weekend in the south, not so good in the north.

      

A good part of England and Wales looks pretty decent with good sunny spells and warm temperatures. Monday looks the best day with temperatures approaching 28C in the south east. Scotland and western parts of England and Wales look cooler with a little rain at times, this becoming heavier and more persistent on Monday. To be honest considering it is a bank holiday weekend the forecast looks pretty decent, especially after a rather poor August if you like settled and warm weather.

All I can say is, enjoy it and crack out those barbecues. 

Edited August 25, 2017 by Captain Shortwave

[Man With Beard]

44 minutes ago, Summer Sun said:

Much closer time frame BH Monday could see 30c in the London area

Yes if I was a being man I'd put money on a 30C somewhere in the next ten days.

The fact that the ECM is perhaps the worst op tonight shows how the models have turned back towards summer. For southern areas, the chance that the front coming south Tuesdayish will be of little consequence before sun/warmth build again. Further north, you'll certainly get s couple of cooler days next week but either side, a fair weekend and then end of the month. Not bad in contrast to recent weeks.

A pretty good week to be off school I would think, particularly in the south.

And yet again the ECM dangles an end of season plume in front of our eyes...

[ANYWEATHER]

8 hours ago, Faronstream said:

As always the high pressure finally moves up to northern europé in September instead of middle of july when we can get severe heat spells, i'm not complaining but i still don't understand why this pattern repeats itself for several years now

Good Evening ! If you look at the ops from both ecm and gfs show no big pressure rise in the ten day period . This I mentioned last night is called the " Disorganized Ripple Effect"  Tropical storms and ex Hurricanes stir the Jet stream into a quandary and the jet stream goes in to a frenzy , and then computer model outputs are completely useless, anyway a completely looking 12z suite from this time last night

Edited August 25, 2017 by ANYWEATHER

[Frosty.]

23 hours since the last post

If anyone is interested, this evening's Ecm 12z turns into a peach of a run for an end of summer / start of autumn very summery spell as high pressure builds in later next week, slowly drifts eastwards enabling very warm / hot / humid continental air to drift north into the uk. And before all that we are already enjoying good bank holiday weather with monday looking very warm further s / se with temps into the 27/28c range for a time and if this run verifies, temps would be even higher than that later in the run..very encouraging run for those of us who want more summer in September! 

Edited August 26, 2017 by Frosty.

[Singularity]

   

Oh yes I am interested Frosty 

It's enjoyable to watch the models back down from the initial assumptions of tropical cyclones simply adding extra oomph to the polar boundary and bringing about a flat westerly pattern such as would most likely result given the coupled-positive AO & NAO pattern evident in the N. Hem view of the charts.

What we see being picked up on instead is a 'mangling' of the jet pattern by the areas of particularly warm air that are moved poleward by the tropical cyclones; this forces poleward arcing of the jet stream where it would not otherwise have occurred, essentially amplifying the overall pattern. When you have a positive NAO, amplification often sees ridges moving NE from the Azores.

Granted, this depends on those tropical cyclones being well-developed enough to move a sufficient amount of warm air poleward. Should either of the two systems visible in the first and second of the N.Atlantic-view ECM charts posted above - which incidentally display more of a subtropical or hybrid form than tropical, particularly the one near Newfounland which is having a go at impersonating Hurricane Sandy of five years ago - turn out to be weaker, we may yet see the simpler boosting of the jet stream take place after all. This would require all of ECM, UKMO, GEM and GFS to be wrong, which is unlikely in the first case at 3 days range, but at 6 day's range is not out of the question. So perhaps a cutting-short of the settled spell compared to the latest consensus... but then again we could just as easily get lucky and drift joyously into mellow fruitfulness .