Model Output Discussion 12z 20/04/13

[SP1986]

Well it's still a fair way out to be certain but, all being typical, I chose to work this forthcoming Bank Holiday Monday and you know the rest. Anyway there is building evidence that point towards a more truly settled spell with more of a continental influence, which may bring some relative late Spring warmth. 

 

The outlook looks fairly dry though, and the showery interlude may well be hit and miss, so some areas could end up with a distinct lack of rain by mid-May if the latest suggestions turn out to be true... 

[NeilN]

North Somerset and Devon would be favoured for some pleasant warmth given the early indications of high pressure to the east of the UK.

 

 

 

Even better!!!! 

[SP1986]

GFS 18z just not interested in pulling high pressure up (and thus elevating temperatures) within the realistic time frame, and instead, after a short live ridge, wants to bring some polar maritime westerly type weather, chilly with showers. This would suggest the outlook is not nailed on with regard to high pressure moving in like the ECM suggests.. at the moment it is potentially 50/50 as to whether the high moves in or low pressure takes over.

 

I'm not going to look at FI as i don't think it warrants any use, I'm sure it'll show high pressure at some juncture, but being that it never comes in the reliable time frame, I'm not really interested in that part of the run.

Edited April 26, 2013 by SP1986

[mountain shadow]

Massive difference between the ECM 12z and the GFS 0z.

The GFS is unsettled and cool where the ECM was settled and warm.

At day 10 the ECM had a 1040mb high over us the GFS has a 996mb low.

Lets hope the 0z ECM doesnt go with the GFS.

Edited April 27, 2013 by mountain shadow

[IDO]

Massive difference between the ECM 12z and the GFS 0z.

The GFS is unsettled and cool where the ECM was settled and warm.

At day 10 the ECM had a 1040mb high over us the GFS has a 996mb low.

Lets hope the 0z ECM doesnt go with the GFS.

Yes, not a great Bank Holiday chart from the GFS 0z op:

It does look from the ensembles that a trough will pass over the UK next weekend, deja vu from this week's setup; a relative dry few days next week in the south (Tuesday till Thursday), as a ridge moves through, then another trough. However at the moment the southern extent is an unknown. The GEFS mean suggests a N/S split: The control run is more UK favourable: ...average but dry for many. ECM on last night's 12z says no to the trough, keeping it to the west, the 10 day mean chart: However it was a similar run to this morning's GFS but the trough pushed through in 36-48 hours (from the 2nd May) unlike the GFS's 4-5 days. T144 on this morning's 0z:

ECM: GFS:

So FI from D7, with the likelihood the models will move closer together to a middle ground. However no discernible pattern for the longevity of either a trough or a UK MLB from the GFS or ECM; changeable Spring like weather with seasonal temps.

Edited April 27, 2013 by i'm dreaming of...

[mountain shadow]

Not much support for low pressure around Norway on the GFS Oslo ensemble, so hopefully thé GFS is wrong.

[mountain shadow]

Thankfully the ECM sticks with the very settled conditions starting next weekend and à country mile different from the GFS

[mushymanrob]

Just to give you all an idea of why I don't presently buy into a long, settled spell for May.

 

Heres a few of the composites from my initial summer forecast research for May (showing 500mb anomaly):

 

First of all, based around the strongest QBO index value years:

 

QBO500mb.png

 

Then with strong ENSO matches added:

 

QBO+ENSO500mb.png

 

And finally, with the two strongest composite years in terms of QBO and ENSO at the same time:

 

STRONG500mb.png

 

It will be interesting to see how long any sort of positive euro height anomaly can be maintained, because the expectation from me is that the Sceuro type trough is likely to become dominant.

 

In fact, the best chance of the summer for a long settled dry spell for me looks likely to be very late May or early June.

 

Only one run, but the subtle changes from the GFS ensembles in the 1-15 day time range is noticeable vs previous outputs

 

Yesterdays 12z:

 

 

Todays 0z:

 

 

You need more than one run to create a trend obviously though, so some tense viewing of future ensemble outputs will ensue I suspect!

 

SK

 

viewing this mornings mjo, anomaly, ecm, ukmo and gfs, i have to agree. the ecm suggests high pressure dominant later in the week, the ukmo not far off, but the gfs, mjo phase 8, and anomaly charts suggest unsettled atlantic themed weather as we get into the first full week of may.

 

perhaps we got abit carried away with fi suggestions of high pressure dominance because we wanted to believe it...

[ANYWEATHER]

Thankfully the ECM sticks with the very settled conditions starting next weekend and à country mile different from the GFS

Yes, but the Ecm is flip flopping all over the place. Tbh, Im gonna go for the gfs solution, as it tends to handle incursions from the Atlantic better than Ecm, although in terms of any model output from t+96 needs to be used with a truck load of salt!!  

[SP1986]

When a model changes suddenly in my experience it cannot be cast aside. In my opinion the GFS should have the upper hand as it stands. I do think the GFS may be closer to the situation as it stands, but there will probably be an element of middle ground somewhere.

[Summer Sun]

So 3 different outcomes at t144 this morning

 

GFS at t144 goes the unsettled route

 

 

Where as UKMO goes a completely different route one which delivers something more settled

 

 

And then ECM goes for something more unsettled probably sunshine and showers the further south you are

 

 

 

If anything this mornings ECM is under-doing the pressure rise for the BH weekend when you look at the ensemble run

 

Op left Ensemble right

 

 

 

Once again positive steps from ECM

 

[phil nw.]

The GFS0z run is a cooler and more unsettled outcome towards the BH weekend against the Ens mean

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=260&ext=1&y=101&run=0&runpara=0

check out the 500hPa and 850hPa temps.

If we compare the ECM mean and UKMO op runs at T144 plus the Ens means i really can`t see any support for the 00z GFS Op run in the medium term.

Edited April 27, 2013 by phil nw.

[bluearmy]

 

viewing this mornings mjo, anomaly, ecm, ukmo and gfs, i have to agree. the ecm suggests high pressure dominant later in the week, the ukmo not far off, but the gfs, mjo phase 8, and anomaly charts suggest unsettled atlantic themed weather as we get into the first full week of may.

 

perhaps we got abit carried away with fi suggestions of high pressure dominance because we wanted to believe it...

 

i'd rather look at noaa cpc and naefs than the mjo forecast and composites. looks ok to me, especially bh and thereafter. no heatwave as yet but certainly no rainfest and the colder runs are dropping out of the extended ecm ens for london as each suite passes.  

[snowmadchrisuk]

Id go for Middle ground , settled in the South , Cloudy and a few Showers Midlands , Unsettled in the North and North West , High pressure looks to be very close to the South and South West on most Models . GFS does swing , but it also quite often swings back . 

[Frosty.]

There continues to be a very strong signal for a warm and anticyclonic spell during may which could last a couple of weeks or so, the signal is stronger from the Ecm 00z ensemble mean but even the GEFS 00z mean, although slower to evolve the settled pattern, does ultimately become fine, warmer and high pressure dominated. The persistent trough to the northwest/north of the uk eventually fills and begins to drift away either nw/n/ne but the issue now is whether the weather will improve significantly by the bank holiday weekend, the ecm is the fast track to summery weather but the gefs mean wants to drag things out for a little while longer, since the ecm is generally regarded as the top performing model on here, I would tend to support it once again, a summery spell on the way then.

 

As for the week ahead, unsettled, cooler and showery across the north at times, more settled with higher pressure to the south with temps recovering towards average.

Edited April 27, 2013 by Frosty039

[snowmadchrisuk]

6z is heading back to a much more settled outlook .. More akin to ECM . I think think this is the more likely outcome , given the Metoffice have supported it for a while. 

[summer blizzard]

All looking good from the ensembles at day 8/9/10.

 

 

The good news is that in the past week its only delayed by about 2 days rather than writing off or keeping it back at day 15.

[Frosty.]

The main difference between the Gfs 06z & Ecm 00z is that the ecm brings an increasingly anticyclonic bank holiday weekend after a bit of a dodgy start on saturday, pressure rises quickly and it turns into a generally sunny and pleasantly warm spell which extends well into the following week, the 6z on the other hand has a very unsettled spell throughout next weekend with the change to settled arriving after bank holiday monday so the ecm 00z op run, just like the ecm mean, fast tracks the settled spell by several days compared to the gfs. Now the latest met office update mentions an unsettled start to next weekend but then steadily improving so it appears to fall somewhere inbetween the ecm 0z and gfs 6z in terms of when the bad weather ends and good weather starts. The week ahead is generally a north-south split with the north unsettled for most  of the week with rain and showers and cold enough for hill snow in the far north and  overnight frosts, the southern half of the uk generally more settled apart from some showers on monday and possibly some showers in the southeast on thursday, but most of next week looks fine with sunny spells and mainly light winds but with widespread slight frosts, then becoming generally unsettled across all areas next friday into saturday before the change to more settled and gradually more summery weather begins to gather momentum.

[IDO]

Next weekend on the ECM we have a high exerting its influence. However both this morning's GFS have a shortwave develop from the NW and this low moves SE delaying the rise in pressure:

Its difficult to know how this does not transpire on the ECM, due to their 24 hour increments, but it doesn't, thus enabling ridging from the AH. Looking at the T168 ECM ensembles stamps: http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2009112700!!/ it does look like there is only minority support for the op, with more members siding with the GFS, to a greater or lesser degree. The 7-10 day mean 500 charts highlight the contrasting models:

for next weekend. Seemingly lots of uncertainty then!

I would suspect ECM to move towards the GFS in the next few runs and also for the GFS to improve the Bank Holiday outlook, especially for the south, maybe closer to the 06z control:

Hopefully Frosty039 is correct with the longevity of a UK HP, however GFS not on board yet. The T384 ensemble's members (FI concerns as usual) have only five out of the 20 showing a HP in charge at that time scale: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=384. So no clear pattern yet. ECM ensemble's mean also showing no clear signs of a warm up right out to D15: , highlighting no clear synoptic warm pattern, though potential from some members.

[Summer Sun]

UKMO is looking more unsettled for the north at t96 this afternoon more inline with GFS

 

[Frosty.]

The fine weather has upgraded next week on the gfs 12z, first of all, next friday looks much better for the south with the jet aligned more sw/ne with high pressure holding to the southeast, a fine day for many areas, indeed, most of next week looks dry and fine across southern britain apart from moday which looks  unsettled but worse for the north, then tues/wed look fine with sunny spells, a risk of rain and showers for the southeast on thursday but fine further north and west across england  & wales, then friday looks fine and saturday also looks fine in the southeast but trending more unsettled from the northwest. Northern britain is likely to be more unsettled next week and cooler than further south but not a complete washout, there will be some sunny weather in the north and another feature of next week for all parts of the uk is it will be cold enough at night for a ground frost or slight air frost but daytime maxima in the south will be heading towards average. Beyond next week the gfs tries to build an anticyclonic spell but there ends up being a battle between a trough to the west and a blocking high forming to the northeast with the uk within the battlezone although eventually high pressure wins but coming back to the reliable timeframe it's looking better for the south. Hopefully the Ecm 12z will be an easier and better FI run to describe than this mess.

[Frosty.]

A very nice looking UKMO 12z at T+144 hours with high pressure from the southwest up to the northeast, only the far northwest of the uk under trough conditions, so the gfs 12z and the ukmo 12z look very good for next friday compared to earlier runs today, ukmo 12z looks good on tues/wed also with high pressure in control across the south.

[Frosty.]

Despite the mixed looking FI on the Gfs 12z there continues to be a lot of ensemble support, especially from the ecm 0z mean and the latest met office update issued this afternoon which is persisting with the settled and warmer further outlook. It's touch and go whether the predicted improvement will save the Bank Holiday weekend but I think there is a good chance that it will be an improving picture at least for southern uk with high pressure building from the southwest/south with northern britain being the last to improve. Let's also remember that we don't even need to look into FI for fine weather, there will be lots of fine weather next week across central and southern parts of the uk  and in the strong late april- early may sunshine it will feel pleasantly warm despite the temps only in the low to mid teens celsius after overnight slight frosts.

Edited April 27, 2013 by Frosty039

[Summer Sun]

ECM looks rather unsettled for later next week tonight

 

[Frosty.]

 Very good to see the ecm sticking to it's guns from the earlier 00z with high pressure gradually taking control during the course of the bank holiday weekend with the trough being squeezed by high pressure and then setting up a very settled outlook as per the ecm 00z ens mean, we are still on course for a prolonged fine spell and a warming trend.