Model Output Discussion 18z 28/07/13

[Frosty.]

Thanks for posting Gibby's reports Gavin, nice to see his highly detailed analysis even though he's not posting here.

Edited September 9, 2013 by Frosty.

[ANYWEATHER]

The met office update today thinks the low will hit so it will be interesting what they say tomorrow, this could be a complete miss, a glancing blow or a direct hit.

Look Frosty. we are in Autumn so perfectly plausible!    

[Frosty.]

Look Frosty. we are in Autumn so perfectly plausible!    

Yep all bets are off now, we could have a cold blast followed by an indian summer, perfectly plausible

[Chris K]

The GEFS 12z control run is very interesting, we go from a very autumnal weather pattern with very cool, wet and windy weather to very summery weather again in a matter of days, this 12z control run best describes what the met office update described today, very cool with strong winds and rain followed by squally showers and then a gradual change to fine, warmer and sunnier weather during the last week of september and into october.

 

Looks like quite a typical Autumn battle being modeled with systems trying to fight their way in whilst also giving chance of some pleasant settled weather at times.  Will hopefully please most with a right mixture of weather if it was to come off as you describe   (obviously there will be changes one way or the other to some degree)

Edited September 9, 2013 by Chris K

[Frosty.]

Well check this out..this is a comparison between the Ecm 00z this morning and the 12z tonight, it's chalk and cheese but I would be very happy with the latest version.

[Captain Shortwave]

Not too bad I guess on the track of the low

 

 

Any weather from this would barely make an impression in the south. 

So ECM/ECM ens/GFS ens show the low staying north of the UK

GFS/control, GEM  have the low hitting the UK

Edited September 9, 2013 by Captain shortwave

[Scorcher]

The main thing is the LP is still showing on every model

 

Well yes but how often isn't there a low in our vicinity, I'm not as certain as you that it's going to hit us directly that's for sure, and neither is the ECM.

[johnholmes]

Bit of a turnaround from this morning? When ECM was all for a trough to the NE?

Must say I was going to call a change to a more unsettled outlook but tonight's ECM wants to turn that on its head - more runs needed!

 

 

The 500mb anomaly charts you show have been showing a similar pattern for several days. The ECMWF synoptic output is quite often different from the 500mb anomaly version. Those can change or at least not be consistent but rarely show the volatility that the synoptic models do.

The NOAA 6-10 output has now altered towards the ECMWF-GFS idea regarding the trough, previously both the 6-10 and 8-14 had pushed the trough fairly well east of the UK. I would wait for another 2 days to see if all 3 are still showing the trough to be the main feature before suggesting this will be the main feature driving the surface weather. Cuurently I would suggest the odds have changed from about 45% to nearer 65% for that.

Edited September 9, 2013 by johnholmes

[draztik]

The ecm 12z op is without ensemble support this evening, with HP reluctant to build as its run progresses, in contrast with the op during the latter end of its run. We have also seen a slide from the gfs ens, to something more unsettled generally, tho as ever, more so in the north and NW. Just a couple of days ago, the ens were showing an all together different story as we moved forward. It now appears, on balance, a more unsettled period lies ahead!

Edited September 9, 2013 by draztik

[bluearmy]

you may recall that i have mentioned the high anomoly in naefs fi not really coming much closer than T324. well it has now come below T300 and starts around the 19/20th.  the upcoming troughing close to our east may well come even further west and this fills a void which was shown to have little or no favoured anomoly a few days ago. we probably hoped the AH would ridge in but alas, the jet seems to be invigorated around the large differences in uppers in the north atlantic approaching the weekend and a vigorous depression seems likely to ensue. so can we still expect the AH to come our way as we get into the final third of the month ? keep watching those naefs anomolys, cpc 8/14 dayers and soon it will be within range of ecm output though the recent london graphical for week 2 seemed quite happy for things to warm up and be on the dry side. 

[Captain Shortwave]

Anybody who likes "exciting weather" want to house swap tomorrow

 

 

What an awful day for the triangle   

Well the GFS is looking a little better this run

Edited September 9, 2013 by Captain shortwave

[Frosty.]

That low bringing the rain and gales to the triangle of doom was made in germany, as the germans would say...wie ist das wetter, I would say das wetter ist going to be wet.

[Tamara]

As suspected the pendulum swings back again a little way. Same message - no face value predictions based on individual model output suites

 

These tell a reasonable story in terms of that. Same signal for a significantly deep enough low, but how overcooked are/have been the more bullish suggestions to dig the trough south? Over amplification deja vu yet again?

 

[Hairy Celt]

So no records broken then, just the hottest / driest etc in recent times. A record is for instance the hottest / coldest day ever recorded. its a bit misleading to be honest.

 

Dunno if this counts, but having just trawled through the MO's data for the Nairn weather station which was established in 1931, it seems that July was the sunniest month on record. Here, July also had the highest maximum temperature since 1933.

[mushymanrob]

The 500mb anomaly charts you show have been showing a similar pattern for several days. The ECMWF synoptic output is quite often different from the 500mb anomaly version. Those can change or at least not be consistent but rarely show the volatility that the synoptic models do.

The NOAA 6-10 output has now altered towards the ECMWF-GFS idea regarding the trough, previously both the 6-10 and 8-14 had pushed the trough fairly well east of the UK. I would wait for another 2 days to see if all 3 are still showing the trough to be the main feature before suggesting this will be the main feature driving the surface weather. Cuurently I would suggest the odds have changed from about 45% to nearer 65% for that.

 

yep, this confirms what my less able brain was thinking viewing the anoms this morning... and they offer no real support atm for the azh ridging in next week after the deep autumnal low sun/mon moves away. the anomaly charts although not exactly the same are still suggesting the azh will stick to our west/southwest and a surface trough will be somewhere to our northeast.

 

so as things stand, the chart runs suggesting high pressure build in fi must not be taken as a 'given'. hopefully we will get another settled spell which would be nice in the afternoons, and there is more hope for this then there was yesterday (when i commented that there was nothing like that this side of t240), there is now, the models have expected this at some time but so far have failed to identify the correct time... maybe this time it will happen.

[Polar Maritime]

ECMWF sending the low much further South on this run..

 

Edited September 10, 2013 by Polar Maritime

[Frosty.]

ECMWF sending the low much further South on this run..

 

Yes PM..which is exactly what the met office update said yesterday.

[Polar Maritime]

Yes PM..which is exactly what the met office update said yesterday.

 

Yes Frosty, a very unsettled period coming up which will be a shock to the system, after the settled weather we have had over the past weeks/months.

Edited September 10, 2013 by Polar Maritime

[Frosty.]

Well yes but how often isn't there a low in our vicinity, I'm not as certain as you that it's going to hit us directly that's for sure, and neither is the ECM.

All I can say is the last 2 Ecm 00z runs show a direct hit of that autumn storm with polar maritime air rushing in behind it compared to last night's 12z glancing blow low.

[William of Walworth]

Just go further North than that is all I hope. Confidence at a maximum of 50% (if that) at the moment for me. Personally, there's a huge amount hanging on how near (or not) any AH influence ends up up being for the few days following Thursday 19th especially ... I see bluearmy is pessimistic (realistic?) on that factor and he may very well be right ...

 

But as most are saying, nothing yet nailed on in the in either detail of positioning. This fingers-crossing day to day is frustrating ... there's been plenty of back and forth switching recently but I'm not liking this over-early autumnal trend

Edited September 10, 2013 by William of Walworth

[No Balls Like Snow Balls]

GFS, ECM, UKMO T144 charts below show the predicted LP at the end of this week affecting all of the UK to varying degrees.

The further North you are the windier and wetter it will be.

 

 

 

 

Below precip charts from ECM 00Z show the North of the UK getting a soaking, the further South you are the lighter and patchier any rain will be.

 

 

 

 

 

Obviously we are still talking 5/6 days away so LP track will change many many times between now and then, if it doesn't disappear totally lol.

 

 

 

 

 

 

[Summer Sun]

GFS is very settled from 216 onwards

 

Just a few of the settled charts from it

 

 

Temperature wise I'd say mid to high teens but the south would be closer to 20c. Cool over night with some fog in places but pleasant by day

Edited September 10, 2013 by Summer Sun

[Summer Sun]

Here is the latest from Gibby

 

Good morning. Here is the report on the outputs issued at midnight for GFS, UKMO, GEM, NAVGEM and ECM for today Tuesday September 10th 2013.

 

All models show Low pressure to the East of the UK with a cold and cloudy Northerly flow bringing rain to the far East, only exiting the SE later tonight. Here it will be distinctly chilly. Elsewhere a slacker Northerly flow will bring dry conditions with broken cloud and sunny spells by day and clear spells tonight. However, all models also show a new set of fronts to the NW slipping SE over the UK tomorrow and Thursday bringing a spell of rain and cloudy conditions to all areas by the end of tomorrow clearing in the North. Then on Thursday the weak fronts by then over the South and West spread back East across Northern areas with rain and drizzle with drier but rather cloudy conditions in the South. By Friday a cold front crosses South with more rain in the South, having cleared the North early in the day. Saturday is then left dry and bright for many as a ridge crosses SE followed by freshening winds from the West with an increase of cloud and rain by the end of the day into the NW.

 

The Fax Charts show the evolution as stated above but with a little more reluctance to clear the rain out of Southern England on Friday as the trough develops a wave. A deepening depression is shown moving towards NW Scotland on Saturday with wind and rain expected soon after term of the 120 chart.

 

GFS then shows a steady build of pressure such as a lot of the second half of the run sees the UK covered in High pressure with attendant fine and pleasant conditions by day with cool and potentially foggy nights given such light winds.

 

The GFS Ensembles are beginning to firm up somewhat on another surge of cold weather between the 17th and 19th as the strong NW winds behind the early next week depression drag cold uppers down from the North. Things are then shown to become average if not slightly above this morning with amounts of rain thereafter becoming relatively small again in the South. there is though a lot of spread in the second half of the run between members.

 

The Jet Stream pattern show upper winds expected to blow SW over the UK ahead of tomorrows rainfall before slackening off and reverting to a West to East motion across Scotland later in the week and weekend before diving South over the UK in the wake of the deep Atlantic depression to the NE early next week.

 

UKMO shows a deep depression heading SE towards Norway early next week with a spell of windy and wet weather crossing all areas followed by cool and windy weather with sunshine and showers soon after. Showers would be most heavy in Northern and Western areas in exposure to the NW wind.

 

GEM today has the same depression affecting the UK in similar fashion early next week moving on to bring the whole complex slowly South into the UK maintaining very unsettled and cool weather with rain at times for all areas of Britain to see out the run.

 

NAVGEM also brings the Low pressure down the Eastern side of the UK next week with a cold and very showery North or NW flow being maintained for some time as the low pressure seems in no hurry to move away from the UK by midweek next week.

 

ECM is less dramatic in its handling of the Low though it is shown to be more effective to the British isles than last night's run with a cold front bringing rain and introducing cool and showery NW winds early next week before  winds back more towards the West with less cool conditions developing but still with a lot of cloud and occasional rain, especially in the NW as weak fronts cross East.

 

In Summary after this weeks changeable but relatively quiet weather conditions it looks this morning like a spell of cool and Autumnal showery NW winds look likely early next week with some heavy and squally showers about in a distinctly chilly NW wind following a band of rain later on Sunday and early Monday. Thereafter the jury is still out with a mixture of options ranging from the deeply unsettled GEM and NAVGEM both of which would maintain very cool and showery weather for all areas to a more modest approach shown by ECM and definitely GFS who bring High pressure back close to the UK or in the case of GFS over us with plenty of fine Autumn weather to be enjoyed. IMO until the exact track of the early week Low is decided I think we will continue to see wide fluctuations in the events shown from the models next week and that may take some days to pin down yet so the model rollercoaster continues.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

 

[Tamara]

Total agreement for a quite deep low to move across approx the GIN corridor, but the question of the degree of amplification of the low remains very questionable.

 

 

At this distance my instinct continues to suggest that the jet stream dig south will be overstated with the pattern flattening out fairly swiftly and pressure rising readily enough in southern and western areas behind the low. A chilly couple of days or so everywhere however, most especially in NE most parts with blustery showers, again mostly in more northern areas - but the further outlook still seems quite likely unchanged from yesterday

[No Balls Like Snow Balls]

GFS 06Z.

 

Looks like quite a wet Friday and Saturday coming up.

 

 

 

 

 

 

Scotland looks like doing ok, until Sunday at least

 

Feeling very cool on Saturday.

 

 

Heavan

 

 

Feels like a very long time since we last saw this.

 

 

 

 

 

 

 

 

 

 

 

Edited September 10, 2013 by No balls like Snow Balls