Model Output Discussions 12z 03/05/2016

[bluearmy]

Interesting developments re the gem 12z pulling the Atlantic trough back southwest again post day 8 to raise another plume. ECM extended eps mean is  very much headed in a similar direction though not quite as quickly. the return of the upper trough is certainly not as sure as looked likely only a day ago. 

[knocker]

According to the wrf some interesting weather running through the border country tomorrow.

 

 

 

Edited July 19, 2016 by knocker

[SenlacJack]

Apologies if this is veering slightly off topic but on a personal level  I find my eyes glazing over at times trying to follow and interpret posts which seem to show a plethora of charts over and over again, often within an hour or so of each other. Not a criticism as such, just an observation.

NB: It doesn't help when folk later quote the posts and include all the same charts already posted again. Just saying.

 

 

[northwestsnow]

I think, on the  whole, one could say the next 7 days might well be the best of the summer so far,it often looks warm and settled away from the North/North west with temps probs average for late July, certainly an improvement from June anyway!

The trend looks a bit better imho this evening.the 18z GFS is an improvment and delays the Atlantic until next wed for the south of th UK, at last something resembling summer !!

edit 18z showing it still warm for the southern UK out to next thurs with temps 20 25 deg widely, very very nice run indeed!

Edited July 19, 2016 by northwestsnow

[Frosty.]

11 minutes ago, northwestsnow said:

I think, on the  whole, one could say the next 7 days might well be the best of the summer so far,it often looks warm and settled away from the North/North west with temps probs average for late July, certainly an improvement from June anyway!

The trend looks a bit better imho this evening.the 18z GFS is an improvment and delays the Atlantic until next wed for the south of th UK, at last something resembling summer !!

edit 18z showing it still warm for the southern UK out to next thurs with temps 20 25 deg widely, very very nice run indeed!

Agreed, for the south, the Gfs 18z shows a lot of fine and warm weather out to later next week with temps into the low to mid 20's celsius and just a few heavy showers at times. It's a north / south split really, the north / northwest of the uk is cooler and more unsettled but the south often has Azores ridging extending across from the weekend to later next week, into FI.

 

[knocker]

Today.

Regarding temperature you can take a sliding scale, hot to cooler, from the SE to the NW with the temps around 30C confined to a line SE from the Humber to Weymouth

Still some violent thundery activity around more particularly in the north but storms could well spring up in the SE and elsewhere. I suspect these charts may have hastened the clearance a little.

Now for the next ten days with the GFS. Friday a weak front traverses the the country bringing with it showery rain to be followed by brief ridging in the south before the next frontal systems arrive Sunday/Monday bringing more showery rain although not unpleasant in the sunny periods with temps a little above average. For the next couple of days pretty much a N/S between the LP/HP before the next system wings in at the end of the week. Temps next week very alternating around the average. Once again pretty much what you would expect within this upper air pattern

Edited July 20, 2016 by knocker

[Eugene]

Some gloriously cool nights next week starting Monday night, a brief cool northwesterly 26th/27th before turning more unsettled, after last night Autumn can't come soon enough.

[Frosty.]

The GEFS 00z mean generally shows a north / south split with the north of the uk more influenced by troughs whereas for the south its the Azores high which is more influential so for the south it means more in the way of fine, sunny and warm weather but with an occasional band of rain and heavy showers with a chance of thunder and temps generally low 20's c but occasionally warmer into the mid 20's celsius but relatively cooler and more unsettled across the n / nw of the uk but with some fine and warmer intervals too. It's normal summer weather which is at least better than the first half of this summer which was generally very poor.

[mb018538]

Pretty much as you were this morning, better in the SE, cooler in the NW. GEM still looks the best, though not as mad as last night!

[Frosty.]

The Gem 00z is another good run for southern uk with plenty of Azores ridging for the south of the uk bringing spells of fine and warm weather, the occasional cooler and showery interlude but more generally changeable and cooler further n / nw, however, later in the run high pressure builds in strongly and most of the uk becomes dry, sunny and warmer. This run shows the south seeing temps in the low 20's c and occasionally mid 20's celsius, especially later on.

[Man With Beard]

Yes pretty much agree with everything above - a mixed bag for the next seven days or so - perhaps a little less positive on the op runs this morning with troughing a little more dominant for next Monday/Tuesday, but the flip side being that the better periods of weather simply return afterwards. The further NW you are, the less encouraging it becomes.

A quick flip through the GEFS ensembles - what strikes me is the increasing mobility in the pattern after D10 - most ensemble members zip low pressures through the pattern a lot faster than they have done recently.

That doesn't necessarily mean worse for the UK - looking closely at D10-D15, the effect of this increased mobility on many runs is to simply exacerbate the tendencies of the pattern - lows headed for the UK are stormier, lows stalled by a nose of the Azores High cause a rush of heights northwards (so possibility of plume no 2 in there), lows guided north by the Azores High seem to encourage a stronger Azores High and attempts at a mid-Atlantic high cause a stronger pull of northerlies over the UK. No sense whatsoever over which possibility will win out.

So although it is often said that all options are open in FI, it really does apply to this run!

[stodge]

Morning all

With the 06Z GFS currently rolling out, I'll keep my comments fairly general. No clear picture this morning with three of the main models all offering differing evolutions of the ongoing struggle between the Azores HP trying to ridge in from the SW and the trough to the NW trying to extend its influence SE.

GFS 00Z at T+240:

Interesting to see the focus of the trough shift more to the NE bringing in cooler NW'ly air but plenty of settled about especially for the south and south west of the British Isles.

GEM 00Z (everyone's new favourite model) at the same time:

The big difference here is the Azores HP transfers to southern Britain. I've not seen this evolution anywhere else but it opens the door to all sorts of possibilities including a return to heat if that HP draws further east. I've got to say it doesn't have a lot of support elsewhere but if it gets picked up later this week by other models, kudos, and a strong likelihood of an August hot spell.

ECM 00Z, which strangely no one seems willing to discuss:

The ridge is hanging on by its fingertips in the south but basically pressure is falling, the Azores HP is retreating and the unsettled forces are gathering.

Note where the 1015MB line is on the three charts if you want a quick guide to the way the model is going.

I also note all three models showing heights over Greenland but GEM keeps the jet much further north than ECM or GFS.

In the short term the heat is on the way out for now but in the medium term plenty of options on the table and, as always, more runs are needed. 

[knocker]

You can transpose the 500mb anomaly on to this quite easily. No significant change in the EPS 10-15 period. It does adjust the HP west and the thus the trough more mid Atlantic for a while but nudges them both again by the end of the period.

Edited July 20, 2016 by knocker

[summer blizzard]

GFS ends July on a cooler and more unsettled note than the Euro or GEM..

[Man With Beard]

18 hours ago, Man With Beard said:

Why have the doom and gloom forecasts gone wrong? Why was no one able to predict this heatwave, or indeed, make room even for its possibility, not 14 days ago?? 

In my opinion, if we are to learn on this thread, we need to spend as much time looking back than forward (I accept you've done this in part, but others haven't)

Can I just mention in here mods - following my post yesterday, I have had a lengthy discussion with Tamara through PMs.

As a result, I would like to retract any implication that I was criticising her methods.

My issue is with the difference between operational and ensemble D10-D15 forecasts and what I'm seeing at ground level (and just to add, probably from a localised perspective, not of those in Northern Ireland!).

I re-read Tamara's post carefully after posting and realise I had not appreciated that she had given a lengthy explanation of why July has transpired as it has done, and also that her thoughts are not primarily based upon GFS/ECM runs anyway.

I hope we can all encourage Tamara to keep posting in here as, whether we take the same view or not, posters like her mak this forum the rich fountain of knowledge that it is.

[Matthew.]

Some big storms starting to roll in ahead of a cold front. Take care.

[northwestsnow]

Very pleased with the GFS12Z so far - saturday looks another beautiful summers day for many with temps 21-25 widely across the country.

 

[mb018538]

UKMO is a bit meh - very average, with the continuation of the NW/SE split theme. Temps around 16c-24c, so right around average.

[Man With Beard]

The GFS seems to be making up its mind for next week - 12z follows the 06z and most of its ensembles - by mid next week, heights in the Atlantic force a more NWly flow and that means cooler everywhere, and eventually the SE too. If this proves to be the case then well done Knocker for calling this a week or two ago. 

On the positive note, though, a NWly in this set-up might mean a fair amount of sunshine, particularly for S facing coasts - and the far SW may see fairly good, warm weather

Edited July 20, 2016 by Man With Beard

[knocker]

One thing we don't want to see is the development of this idea which it seems quite keen on this run. Anyway It is but one run, all change tomorrow.

 

[stodge]

Evening all

Have to say the 12Z output so far has been far from inspiring and a definite step back for those hoping for a prolonged settled spell.

GEM, which was very bullish last night, now offers this:

This would put us in all kinds of trouble for August with the trough close by and a N'ly or NW'ly component, rain would never be far away and temperatures would be suppressed.

GFS 12Z OP at the same time:

Not great but no mid-Atlantic ridge and heights not so pronounced over Greenland so some hope and further into low-res the Azores HP seems to get its act together once again.

We await ECM...

[knocker]

The ecm has fronts moving across the UK Sunday/Monday associated with the low pressure area lying to the NW/N. The UK stays under the influence of the latter until Wednesday in a cool NW airstream  Then some brief ridging before the next system arrives on Friday.

[Fourty Point Three Degrees]

1 hour ago, stodge said:

Evening all

Have to say the 12Z output so far has been far from inspiring and a definite step back for those hoping for a prolonged settled spell.

GEM, which was very bullish last night, now offers this:

This would put us in all kinds of trouble for August with the trough close by and a N'ly or NW'ly component, rain would never be far away and temperatures would be suppressed.

GFS 12Z OP at the same time:

Not great but no mid-Atlantic ridge and heights not so pronounced over Greenland so some hope and further into low-res the Azores HP seems to get its act together once again.

We await ECM...

I had a sense of some 'punishment' weather coming up for the recent stealing of a days worth of Spanish climate 

[Frosty.]

The Ecm 12z indicates largely fine and warm weather this weekend due to a ridge of high pressure and temps in the south of the uk should be into the mid 20's celsius, however, there is a risk that some of us could catch some showery rain too. Into early next week turns more unsettled with sunshine and heavy showers with thunder due to trough intrusion from the northwest which lasts until next midweek with cooler temps but then later next week the trough fills and the remnants drift away NE as another ridge extends across the south with increasingly fine and warmer weather returning to southern areas but another trough is waiting in the wings to end the run. It's a changeable outlook but at least the south would have some fine and warm spells between the rain and showers.

[Scorcher]

The ECM ends pretty well for me- there is a trough to the west yes but I could see another plume developing from that setup if the trough stalls out to the west. We've seen that happen a fair bit over the last few summers. Relatively few outstanding large areas of high pressure over us (except for July 2013 of course), but quite a few short spells of hot weather with troughs stalling out in the Atlantic.