Model Output Discussions 12z 01/06/2017

[Allseasons-Si]

The ecm mean is a lot better than the 0z,at 240 hrs we have the best ridge of high pressure at 1020 than the rest of the world at our latitude,bring it on

Edited June 6, 2017 by Allseasons-si

[Singularity]

Thanks for the detailed round-up @Tamara , I keep losing track of the GWO/GLAAM developments as - ironically - I spend so much time working on other areas of research and development .

So while on the face of it the model trend this evening resembles a backing-down from having shown too much of an MJO phase 6 response, this is really more of an overdone IO forcing by GEFS (in particular) that happens to bear close resemblance. The usual horrendously large negative GLAAM bias beyond about a week's range. At least knowing of that I was expecting an improvement in that model's output anyway .

  

So now we have two models (UKMO and ECM) moving the weekend low very slowly through to Sun with the SE tasting the fringes of a continental plume - at the risk of some destabilisation impacts perhaps, depending on the interplay with the base of the trough (i.e. with associated upper convergence and divergence regions).

GFS remains more progressive but has trended slower over the past four runs. 

  

As if for a laugh we then have ECM flirting with a Scandi trough more than the other two, but this looks to be driven not by a GFS-like overcooking of IO forcing but instead a more meridional jet ahead of the large-scale deceleration. This could just be the model showing it's amplification bias - though the range is a bit short for it to be a major factor.

   

For 8 days from now, the evening runs feature one very pleasant outcome, one rather cool but drying up and trending warmer afterward as the ridge drifts east, and one with an impressive blocking high sat right overhead (thanks to split jet setup as explained by CreweCold earlier).

Not bad going at all  

Interesting that it appears GEM may well have some of the negative GLAAM bias that GFS does, though it's also known to over-amplify so the true balance of play is somewhat mysterious.

[Ice Man 85]

Wish you guys would speak english

[Sky Full]

I am very much liking the way the models seem to be in general agreement with their predictions for mid-June:

GFS 12Z:

ECM:

GEM:

Dont know what UKMO might have up its sleeve because they won't let us see that far ahead!

If the patterns still look like this in a few days time we would be very close to a warm settled spell of proper summer weather.   I wonder if the current unusual degree of consensus between the models means that these predictions are pretty much in the bag?  I have to say that a change from the current windy, wet, showery, quite cold (and did I say very windy) weather will be exceedingly welcome in these parts.

 

[Nouska]

On 23/05/2017 at 13:48, Glacier Point said:

There are two years which illustrate why the coming few weeks will be keenly monitored.

During 1995 and 2007, two completely different summers (dry and warm versus blocked and wet), the evolution leading up to and during the breakdown of the polar vortex was very similar. However, what followed in the stratosphere and upper part of the troposphere were completely different. During 1995, a cooler stratosphere and lower heights extended their influence much lower into the atmosphere and the resultant weak polar easterly flow was characterised by much less blocking. Contrast that with 2007. The extension of low heights was much less, with blocking (positive height anomalies or red shading) much more robust in the lower part of the atmosphere.

Looking at the profile to date, the extension of low heights is impressive and suggests something more akin to 1995 is the case (although there is still some time for similarities with 2007 to rear their head). It is the speed of the atmospheric response to the breakdown of the stratospheric polar vortex that is most telling for me.

I've lifted this from the in depth model thread as it seems pertinent in view of the lovely 12Z run from the GFS. Nice assessment from GP, all based on teleconnections.

You are suffering the 2007 bit currently (get it out of the way quick ) but the 1995 redux is showing in all its glory from next weekend. Just a reminder of what the charts looked like for back then.

http://www.meteociel.fr/modeles/archives/archives.php?day=15&month=6&hour=12&year=1995&map=0&region=&mode=2&type=era

 

[mb018538]

Morning all -

This mornings runs thankfully reinforce last nights output, in that high pressure builds in and settles things down & warms up. The runs vary in the time it takes to bring the high pressure in, but all eventually get the job done. Summer could be making its return in a week folks.

[mountain shadow]

Just now, mb018538 said:

Morning all -

This mornings runs thankfully reinforce last nights output, in that high pressure builds in and settles things down & warms up. The runs vary in the time it takes to bring the high pressure in, but all eventually get the job done. Summer could be making its return in a week folks.

Was just about to post the same. From around day 8, high pressure in control. Lets hope the models start firming up on this soon.

[Summer Sun]

The beebs thoughts on Sunday for high pressure to move in next week are starting to show now on more than one run

[Singularity]

   

As much as the trend from the ECM, GFS and UKMO models has slowed the weekend low and kept it further northwest, GEM remains distanced from them with a much quicker weakening of the Atlantic low with the plume hanging on across much of the far-S right through until late Monday. A slower ridge arrival next week is the price paid, but it's still on a par with ECM even though in that case it's due to how that model keeps the jet so flat across the Atlantic until Thursday with a very shallow disturbance finding its way across to interfere with proceedings.

Anyway - I'd be amazed if GEM was victorious at such short range, but I am inclined to see some further slowing down of the warm air removal as a probable trend in the other models, in which case GFS and UKMO may also slow the ridge arrival next week but frankly I'd be very happy if it arrived by mid-month and then tended to stick around or keep on reloading for the following 10 weeks or so... is that too much to ask for?    

[Fourty Point Three Degrees]

The 06z is nothing special with termps refusing to reach above 21c.

[Summer Sun]

UKMO shows high pressure moving in by Tuesday

[weathermadbarnsleylad]

3 hours ago, 40*C said:

The 06z is nothing special with termps refusing to reach above 21c.

12z looking better 

[weathermadbarnsleylad]

24 minutes ago, Summer Sun said:

UKMO shows high pressure moving in by Tuesday

That's what I like to see

[Singularity]

   

Still an unusually large range of minimum pressure values being produced for the low affecting the UK noon Sunday;

GFS is near 992 mb whereas UKMO is around 998 mb and GEM 999 mb.

So GFS is responsible for most of that range at the moment - I wonder which end of the spectrum will ECM align with? Probably neither; slap bang in the middle for ultimate lack of clarity 

It's an important detail as it determines just how strong the breeze is during the weekend as well as how quickly the warm sector moves away east. So a big impact on how warm or not it feels across the UK. Of course the SE will be warmest of all and could see temps several into the 20s on Sunday if the warm sector hangs around long enough.

It should be cleared by Monday though; GEM has backed down on the lingering plume-like outcome. 

  

Question now is whether the models are still taking the mid-Atlantic poleward amplification too far. GFS has reduced it for mid-week but increases it for the rest of the week. GEM is just more amplified overall (model bias?).

[mb018538]

ECM not bad either, not as high pressure dominant as other runs and the previous 2, but does scoop up some very warm air towards the end of the run. Too far out for exact details at this range, but the right trend is emerging.

[Summer Sun]

4 minutes ago, mb018538 said:

ECM not bad either, not as high pressure dominant as other runs and the previous 2, but does scoop up some very warm air towards the end of the run. Too far out for exact details at this range, but the right trend is emerging.

 

You can say that again just look at mainland Europe!

[Singularity]

 

Okay so ECM is notably slower to move the warm sector away on Sunday, enough so that the mid-20s look feasible in the SE corner.

It then turns into a very progressive run, so quite the contrast to GFS and GEM. As tropical maritime air is thrown east across a wide swathe of anomalously warm waters that lies adjacent to the western coastlines of northern Africa and western Europe, the usual heat build is accelerated and some impressive temps result after just a few days.

It's because of this manner of logic that I can see why some long range outlooks highlight an increased chance of extreme temperatures across NW Europe this year. Having that include the UK is another matter - and one that may divide opinion on here given that record-challenging temps = dangerous temps for human health.

The heat build potential is similar to that of 2015, but that year we had cooler waters in the vicinity of the UK plus interference from a developing El Nino, which both played their part in driving a strong jet stream along the major temperature boundary between the hot continent and cool seas. It only really broke once, and boy did we know about it (30th June to 4th July, peaking 1st July).

I do feel ECM is being a bit overly mobile with those lows this evening though - a slower build-up of heat seems more likely. I also wonder how easily we can achieve the level of stability required to avoid quick thundery breakdowns. Hopefully the similarities of the Atlantic-Europe sector patterns with those of 1995 will bear fruit in that respect.

[carinthian]

3 hours ago, weathermadbarnsleylad said:

That's what I like to see

I think you will like this latest chart better still in the extended UKMO N.Atlantic.

 C

[ANYWEATHER]

Evening all .So we all want Summer and yes gfs gives us it for a while later next week ,but ecm is not so responsive...watch the gfs follow the ecm tomorrow

[Scorcher]

The ECM is an odd run after what has gone before. Only yesterday the models were going for the opposite option to what the ECM 12Z is showing, with the high staying out west in the Atlantic. Even the GFS 06z earlier on showed that scenario.

I imagine this run is one of the more extreme options in terms of the Atlantic strengthening again. It's a warmer run for the south but it looks like a cloudfest for areas further north- possibly even for everyone away from the SE corner.

[Allseasons-Si]

I don't think we should be too downbeat at the models this evening/tonight,at least they are showing a dry scenario and the models(as they do) wether it be winter or summer etc do have wobbles and will not be precise this far out if it is a hot spell you are looking for,the trend is an HP cell somewhere close to or near to the BI

now i have just looked at the 6-10 day and 8-14 day 500mb outlook from NOAA and i have got to say it is looking a lot better than last nights where there was some ridging through the uk then building north to allow a southerly tracking jet,tonight however has more of a Hp influence on the uk and the 8-14 dayer has a southerly fetch,i am a little bit happier with this than last night's

as it stands,trough to the west and HP cell building east of the BI,loverly

and again,you can't knock the mean from the ecm,pretty similar to last nights

Edited June 7, 2017 by Allseasons-si

[weathermadbarnsleylad]

3 hours ago, carinthian said:

I think you will like this latest chart better still in the extended UKMO N.Atlantic.

 C

Looks high pressure heaven  on ukmo, not too happy with ecm 12z 

[weathermadbarnsleylad]

7 minutes ago, weathermadbarnsleylad said:

Looks high pressure heaven  on ukmo, not too happy with ecm 12z 

It brings in the heat but no much high pressure close by

[Fourty Point Three Degrees]

Is the net weather model site down? Page keeps freezing and cant view charts.

[Cheshire Freeze]

Hard to tell whether GFS is being too trigger happy and following the trend we've seen for a while now with the modelling (overamplification in the later stages of runs) or whether this overshooting of HP will become a firming trend as we progress through June

Day 7 shows us the ridging HP across the UK bringing predominantly dry, settled and warm weather

However by day 9 we can already see a gain in latitude of the HP with the jet starting to creep underneath the HP

From that point it's a matter of when not if pressure falls from the SW...

Something to keep tabs on over the next week or so.

Also keep an eye on the CFS mean for July, along with the other longer range forecasting tools to see whether we can get any sort of convergence of ideas for the longer range. At present, the CFS has trended towards a mean mid Atlantic ridge- cooler than some would like perhaps but not necessarily that unsettled.