Model Output Discussions 12z 03/05/2016

[phil nw.]

GFS 06z shows the cooler air coming in overnight Tuesday with a possible thundery breakdown in places.

This brings quite a drop in Maximum temperatures compared to Tuesday-the expected peak of the hot plume.

so the outlook continues to be modeled pretty much as expected with conditions returning to our more usual pattern later next week.

Day 9 from both ens charts.

so not looking too bad further on.A gentle westerly,fresher setup with many areas still looking quite dry after any breakdown rain next week.

 

[Frosty.]

Yes the plume looks like a non event now, pity.

[A.J]

personally, I'll just continue monitoring the model outputs over the next 2-3 days before passing any personal judgement on what may or may not happen next week....To write off weather a week before it's happened is foolhardy IMHO. The model output can and possibly will change between now and then

Edited August 10, 2016 by ajpoolshark

[stodge]

Afternoon all

So how have things moved on since yesterday ?

As far as the "plume" is concerned, the GFS 00Z OP still looks encouraging for fans of heat (T+168)

The 16c 850HPA line remains over the country for 48 hours so two very warm to hot days and three hot nights in the south east on that.

Unfortunately, the 06Z is much less favourable (T+162):

The brief warm or very warm spell clears through after 36 hours (and like yesterday's 06Z OP run starts earlier than the 00Z) and the 20c 850HPA never gets near the UK.

Much the same from the ECM 00Z OP:

And with GEM, it's already game over:

The original premise of the heat building Tuesday to Thursday seems to have been undone by the inability of the block to build strongly enough to the East to slow the Atlantic allowing the S'ly to set up. The more progressive models (ECM, GEM) start the heat sooner and end it quicker - GFS remains the last flicker of hope but to be fair the big boned operatic lady is now in the building has reached the stage and is clearing her throat as the introduction starts.

Moving beyond "that was the plume that wasn't", there are a variety of later evolutions. GEM throws up a NE'ly moving compact little storm while ECM mirrors yesterday's GEM with the trough over us and a warm E'ly:

GFS 06Z keeps a summary theme with HP never far away and a possible short-lived re-boot of heat:

All in all, fans of summer shouldn't dismiss the GFS as it's far from unreasonable.

[Northern Sky]

Quick question. Does anyone know if the BBC website forecasts are computer generated or is there input from actual weather forecasters? If they are just generated from model runs wold that be from the UKMO model and the ECM - seeing as the forecast is to day 10?

A couple of days ago the temp for Leeds next tuesday was 30C now it's only 23C would that be a reflection of the operational runs or an amalgamation of all outputs? It's not really important I was just curious and as someone who doesn't really care for hot weather I'm hoping the 23C forecast is nearer the mark!

[mhielte]

2 hours ago, ajpoolshark said:

personally, I'll just continue monitoring the model outputs over the next 2-3 days before passing any personal judgement on what may or may not happen next week....To write off weather a week before it's happened is foolhardy IMHO. The model output can and possibly will change between now and then

Absolutely.

I'm surprised at some of the more prolific posters in this thread seemingly living and dying with each run. Look to the ensembles for consistency and agreement, rather than accepting every operational chart as gospel.

[Methuselah]

54 minutes ago, mhielte said:

Absolutely.

I'm surprised at some of the more prolific posters in this thread seemingly living and dying with each run. Look to the ensembles for consistency and agreement, rather than accepting every operational chart as gospel.

If you think it's bad now, wait until winter!

[Scorcher]

7 hours ago, Nouska said:

The ECM cloud cover for 18Z Saturday looks a little better.

  

@Scorcher You'll get the ECM 6 hourly time steps you like on the IMO weather page - limited view and limited parameters but better than nothing.

http://en.vedur.is/weather/forecasts/atlantic/

An edit to add the ARP cloud for same time, this shows the different cloud levels.

http://www.meteociel.fr/modeles/arpege.php?ech=3&mode=38&map=330

Very interesting, thanks. Yes if the cloud cover charts there are to believed there would be significant clearing for most of us on both Saturday and Sunday afternoons. Also good clear spells south of Cumbria most of Friday. Monday looks clear for most according to those charts.

[Man With Beard]

2 hours ago, mhielte said:

Absolutely.

I'm surprised at some of the more prolific posters in this thread seemingly living and dying with each run. Look to the ensembles for consistency and agreement, rather than accepting every operational chart as gospel.

I completely agree with you - in all honesty, the charts have been pretty consistent for a slightly extreme situation. Still hot Tuesday with 90F in sight on GFS (not record breaking but the only way is down from perfect!), and maybe hot on Wednesday.

But the fun really starts on Wednesday. The UKMO often trumps the other models with the SW low coming up against heights to the east - and look at Tuesday, it's already got a blown up trough way to the SW. Could it slide underneath us?? I'm now wondering if northern areas will get a better second half of the week than they expect. It's all developing nicely!

Also, some people saying this is not a plume? It certainly still is. A straight line run of heat moving up from Spain. We've been a bit spoilt by super plumes last month and July 2015, but it certainly is a plume.

Edited August 10, 2016 by Man With Beard

[Frosty.]

Well according to the Gfs 12z it's not much of a plume anymore in terms of longevity or heat, nothing like the 34/35c it was showing recently but it does become warmer and more humid from the south through monday and tuesday with temps into the high 20's celsius across most of England and Wales with plenty of sunshine but then a breakdown occurs on wednesday as fronts push rain in from the west which looks heavy with a risk of thunder but very warm ahead of the rain further east but cooler and fresher behind it. Thereafter it looks unsettled but with high pressure occasionally ridging across the south with some fine and warm spells further south.

[SMU]

I wonder if Man with beard is getting worries about stripping off his clothes yet!

 

s

[Frosty.]

Hmmm I see what you mean about the ukmo 12z man with beard, looks intriguing with that low to the southwest looking like it would slide under the block!

[Frosty.]

1 minute ago, knocker said:

Assuming the upper ridge and trough don't move east in concert?

Absolutely Malcolm, nice to see you posting again by the way

[Frosty.]

As you can see from the Gefs 12z mean snapshot for next Thursday, there is no support for prolonging the plume, if it can even be called a plume..it seems like an insult to even call it a plume seeing as it only lasts 1 day (Tuesday) 

[Evening thunder]

Tbh from what I've seen it was only that extreme GFS run (and perhaps a few others) that showed anything significantly longer lasting in terms of the plume than some of today's runs, only that one run actually showed 34C on it's temp charts, but typically it under-does maxima a bit so I expect we will still get 30C somewhere.

This looks like a plume to me, which by their nature are typically not long lasting affairs. 

Though of course it seems the GFS was wrong with it's rather more high pressure dominated outlook it showed recently.

[Nick L]

And this evening's ECM comes in even cooler with maxima of just 24-25c on Tuesday (yes of course some places will be warmer). There's only one trend with these temperatures for next week, and it ain't up!

Interestingly though, it stalls the front out west a little longer on Wednesday.

Edited August 10, 2016 by Nick L

[Captain Shortwave]

The ECM seems very pessimistic, giving 25C as a maximum given 850s of 14/15C and a south easterly wind, that said we will probably see 30C being the maximum now on Tuesday. We have generally seen a trend to weaken the strength of the ridge pushing north which hurts temperatures on two fronts, low 500mb heights and lower 850s. That said the ridge stretches further north which could have other consequences.

Todays ECM

   

Yesterdays 12z

   

That said I suspect we are seeing a trend to prolong the very warm and more settled spell, especially in the east, I do wonder whether we will see high pressure hang on into the second half of next week.

Tonights ECM vs yesterday

   

Well the ECM is warmer and more settled for Wednesday away from western areas where low pressure could bring some rain (possibly thundery). Temperatures again could reach 30C in the south east.

Edited August 10, 2016 by Captain Shortwave

[Nick L]

1 minute ago, Captain Shortwave said:

The ECM seems very pessimistic, giving 25C as a maximum given 850s of 14/15C and a south easterly wind, that said we will probably see 30C being the maximum now on Tuesday. We have generally seen a trend to weaken the push of 500mb heights and also the northwards push of heat from the south. 

Todays ECM

   

Yesterdays 12z

   

That said I suspect we are seeing a trend to prolong the very warm and more settled spell, especially in the east, I do wonder whether we will see high pressure hang on into the second half of next week.

Tonights ECM vs yesterday

   

Well the ECM is warmer and more settled for Wednesday away from western areas where low pressure could bring some rain (possibly thundery). Temperatures again could reach 30C in the south east.

Yep, ECM takes but also gives. It really cools down Tuesday, but by stalling the front a little longer it could give a much warmer Wednesday for eastern areas. Interesting times.

[Frosty.]

The Ecm 12z still looks pretty warm next week, mid to upper 20's celsius.. these are still good charts by this summer's miserable standards!

[Man With Beard]

1 hour ago, Steve Murr said:

I wonder if Man with beard is getting worries about stripping off his clothes yet!

 

s

A little worried after seeing the latest ECM!!!

But I agree with CS's logic, I still think the max on Tuesday will have a 3 at the beginning. So if anyone wants to see me strip, you'll have to go to Southsea Beach...

And here we go with the trough disruption chaos! Expect to see many solutions coming up for the Wednesday to Saturday period next week! Tonight's ECM eventually parks a low over S England and northern parts get a decent Thursday/Friday too, as heights to the north back west! In fact they do so well backing west, we end up with a coolish NEly. The first major Atlantic fail on an op run in this period, but I doubt it will be the last.

[knocker]

At Weds 06z the ecm has a couple of perturbations forming on the approaching front that coalesce as they move east and form a general area of low pressure orientated NW/SE over the UK and eastern France by 12z Thursday with much convective activity, particularly over Europe. This area of low pressure then tends to swing north on it's axis under the Scandinavian high pressure that has been a tad reluctant to drift NE. Of course this all a bit academic at the moment.

 

And at the end of the day I think I'll just wait for the anomalies

Edited August 10, 2016 by knocker

[Frosty.]

What's so bad about the ecm 12z..it's a cracker for warmth next week!!!!!!!

[knocker]

Tonight's 6-10 anomalies are all on the same page. Deep low over the Pole, HP northern Scandinavia an a negatively tilted trough in the eastern Atlantic. This could well indicate a surface evolution not dissimilar to this evening's ecm det run with perturbations on the southern flank of the main area of low pressure running east with potentially some dramatic convective activity over the UK and France/Germany. Just prior to this still looking at temps in the upper 20sC on the Tuesday but dropping to around average as the evolution unfolds.

In the later period a similar pattern with less amplification suggests a westerly flow with a familiar N/S split with the more unsettled weather tending to concentrate to the north and temps varying around the average.

 

[Frosty.]

The Ecm 12z ens mean shows a very warm and humid continental Sly / SEly airflow for most of next week with temps in the mid to upper 20's celsius and even into the low 30's c in the s / se for a time around next tues / wed. The week starts settled under high pressure but as the high drifts further east, pressure starts to fall and there is a growing risk of thundery weather, especially around the middle of next week. Beyond that it becomes brighter and fresher but still warm with temps into the low 20's c with sunshine and showers, still some heavy and thundery. 

[knocker]

Morning campers - a brief look at this morning's GFS starting with the weekend.

Midday Saturday sees the UK in a cool NW airstream with a few showers in the north otherwise mainly dry. But HP is nudging in from the SW and 24 hours later a high cell is centred over the Irish Sea so a dry cool day for all. At  the same time, in this quite mobile pattern, a frontal system is girding it's loins out west.

From this point the HP moves east, then north, accompanied by a similar movement from the front ( just east) on which small perturbations form, so that by 18z on Tuesday the front lies just to the west of the UK. This scenario briefly introduces some WAA from the south so that the southern part of England will, again briefly, be quite warm with temps around the 28C mark.

The front continues the movement east bringing thundery outbreaks and possibly some substantial down pours to some areas over Tuesday/Weds. Eventually this system swings on it's axis and ends up over N. Germany as it slips under the high pressure which is now to the NE with once again the HP edging in from the south west.

Overall the next seven days are quite dry with the only substantial rainfall in NW Scotland. This is of course not taking into account possible localised rainfall from convective activity next week.

 

Edited August 11, 2016 by knocker