Model Output Discussion 18z 28/07/13

[Summer Sun]

ECM is once again showing the low moving down mid next week though for most it remains warm however.........................

 

 

...................By Thursday a new possibility has developed

 

 

So tonight the colder low has been removed  with pressure fairly high still it could stay dry for many and pleasantly warm in any sun maybe even very warm in the SE at times

 

Edited August 28, 2013 by Summer Sun

[Summer Sun]

Completely different end to ECM than what we had 12 hours ago

 

 

This morning

 

 

Much better run from ECM this evening maybe its picked up on a new trend and that cooler low was just a tease

[Man With Beard]

Completely different end to ECM than what we had 12 hours ago

 

 

This morning

 

 

Much better run from ECM this evening maybe its picked up on a new trend and that cooler low was just a tease

I'd certainly like this to be true but it's the first time we've seen this possibility. More runs needed!

[Milhouse]

They couldnt be more different that is for sure. What is looking likely though is some warm moist air coming in off the Atlantic for the first part of next week and a suggestion that winds might tilt more southwesterly meaning added warmth and the increased chance of a plume type situation as the ECM is indicating.

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

 

evening  all i see deep in to fantasy world  it looking  a bit  wet  at  the  moment

[AWD]

Now I don't want to be a killjoy here or anything but I really would be very sceptical about the later stages of the EC Det output tonight as simply put, it doesn't have great support currently.

The swing between the last two EC Det outputs has been like chalk and cheese, thus any confidence in medium range operational output has to be very limited at this moment in time. There really are better products available to us to give a better idea of any trend into the medium and long range time period than the ever varying operational model output.

By medium to long range, I of course mean 7+ days away.

If we look at the updated 500mb anomaly charts, the EC and GFS version are actually really rather similiar;

Both show an upper trough rather than an upper ridge dominating our weather. Any ridge looks to be in the mid Atlantic towards the eastern seaboard. A westerly, sometimes north westerly flow also present there suggestive of nothing notably warm either.

The NOAA version also similiar too;

Again an upper trough dominant there.

A look at the NAEFS output (admittedly the 0z as the 12z hasn't updated yet) also showing a dominant trough over or close to the north of the UK in the 7+ day timeframe;

I can't see the 12z output varying too much from this suite.

The GEFS also showing more average to slightly cooler than average upper air temperatures into the 7+ day time period;

Certainly fewer warmer members than there were a couple of days ago there.

So all long range ensemble and anomaly guidance in broad agreement of a rather typical early autumn pattern emerging from the end of next week onwards. Whilst the operational output continues to swing about, I know what data I will be following more closely for the time being.

I know this isn't going to be the most popular of posts in here, but I do feel it's something that really needs to be considered to avoid to much dependance on preferable operational output.

Edited August 28, 2013 by AWD

[Milhouse]

I know this isn't going to be the most popular of posts in here, but I do feel it's something that really needs to be considered to avoid to much dependable on preferable operational output.

 

No, i think you are quite right to point that out and you make some good observations. With a ECM mean like this mornings 0z i will always take the 12z op with a huge pinch of salt.

[Summer Sun]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

 

evening  all i see deep in to fantasy world  it looking  a bit  wet  at  the  moment

 

Not according to the ensembles

 

 

Certainly no mega washout coming sunshine and showers is they way I'd describe it this evening

Edited August 28, 2013 by Summer Sun

[Summer Sun]

Here is the latest summary on the models from Gibby

 

Good evening. Here is the report on the 12 noon outputs from GFS, UKMO, GEM, NAVGEM and ECM for Wednesday August 28th 2013.

 

All models show a weak ridge of High pressure across the UK with a weakening front crossing SE tonight delivering no rain of consequence and becoming obsolete by dawn. Tomorrow sees another slightly more active trough follow a similar route through tomorrow and tomorrow night with sunshine becoming more of a premium than of late as cloud and a little rain moves down over most areas from the NW. This then clears SE leaving a cool and breezy NW flow over the weekend with sunny spells and fine weather for most though a few showers are likely in the North.  The nights will become cool and Autumnal feeling everywhere. On Monday the weather stays dry and fine in the South and it may feel a little warmer as winds back towards the West. The north could see fronts cross East in the West flow with cloud and some rain, especially in the NW.

 

GFS then shows the South remaining fair for a time before a trough crosses East midweek over the UK with a spell of rain for all followed by a cool ridge of High pressure by the end of the week. This clears SE at the weekend as another Low pressure area becomes dominant from the North with some rain for all followed by a strong taste of Autumn in a strong NW to North flow with frequent showers in a squally cool wind. Rather changeable weather will continue until the end of the run with some rain at times in temperatures close to average in association with Low pressure positioned to the North of the UK.The GFS Ensembles show a dip in uppers at the weekend before a short warmer phase in the South early next week. Thereafter more average conditions look likely with rain events a little more frequent in the South than of late. The operational was a cold outlier in it's 10-12 days range.

 

The Jet Stream shows an undulating pattern developing from the weekend as the main trajectory of the flow transports further South towards the 50-55 deg N latitude area.UKMO tonight shows a North/South split again tonight with Northern areas seeing a fresh Westerly wind with occasional rain while Southern areas see more cloud than of late too but still mostly dry weather with a little sunshine and temperatures close to average.

 

GEM shows Westerly winds over the UK throughout it's output tonight. There will be occasional troughs in the flow bringing rain at times across the UK, only a little in the South with long dry spells in between while the North see the most windy and unsettled conditions overall.

 

NAVGEM tonight shows a slow deterioration in conditions in the South later next week as High pressure slowly becomes pushed back further to the SW as a trough gradually slips down from the North.

 

ECM tonight shows different synoptics again tonight as this morning complex UK Low pressure at the end of the run is substituted by a series of weak fronts sinking SE over the UK amalgamating to the SE and developing Low pressure in situ over Biscay. There would be some rain or showers in the South  for a time before the Low drifts slowly North to the SW of the UK sucking warmer air up into the SE again with some thundery showers possible. 

 

In Summary tonight the models are still struggling on whether to bring Autumnal conditions South to affect all of the UK or whether to maintain something akin to Summer in the South. Tonight's models indicate something of a halfway house on those two options with the trend for gradually cooling conditions in the South especially at night. There is also a tendency to bring the risk at least of some precipitation to the South at times later next week with most output suggesting this to a greater or lesser degree.

 

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

 

[draztik]

Here are the updated ECM 12z ensembles for London and Glasgow

 

London

 

Glasgow

 

Illustrates the apparent North/South split, that some have been suggesting, though even the SE is not immune to rainfall at times.

[I remember Atlantic 252]

Just for the fun, one for the heat lovers

 

its changed now, didnt look like that earlier, but was a classic yeah

[bluearmy]

If we look at the updated 500mb anomaly charts, the EC and GFS version are actually really rather similiar;

image.jpg

Both show an upper trough rather than an upper ridge dominating our weather. Any ridge looks to be in the mid Atlantic towards the eastern seaboard. A westerly, sometimes north westerly flow also present there suggestive of nothing notably warm either.

 

 

 the same output from the 12z's was rather a different story re agreement and appearance re ecm. 

 

http://www.meteo.psu.edu/~fxg1/ECMWF_12z/test8.gif

 

 

today's 12z ecm op leads that output to be unhelpful. if either gfs or ecm ops are outliers, then these meteo.psu charts are 'chocolate teapots'.

 

although the 00z ecm spreads did show a clustering taking the trough to our sw, thats certainly not the favoured option. however, i am reminded that the diving trough has been a feature of the summer so a final hurrah as we enter autumn would be less than a complete shock.

[johnholmes]

little time to discuss but as always caution

NO chart from whatever source should be used to suggest a pattern, the anomaly charts are no different, wait for 2-3 days=similar=probable pattern, 1 day only=probably just a one off

and with the ec-gfs use the same time issue don't flip from 00 to 12z

 

Although the last day or so seem to suggest the trough becoming more dominant than the ridge at 500mb, I feel it is too early to decide which and there is insufficient agreement between the 3 I use over a 3 day period to be sure enough which is showing as the dominant feature.

Edited August 28, 2013 by johnholmes

[Isolated Frost]

EC ENS 192 pointing towards that digging trough with the PFJ at a NW-SE tilt; the EC DET generally agrees but pulls in more continental air with a more unstable PFJ; and a slack trough which moves into the subtropics-

The end scenario seems to be anything between wet and mixed rPm, Pm and Tm airstreams from the west and north-west; or the DET solution of negative height tilt (Azores high) and an Iberian trough, with continental airstreams dominating. Many solutions available; with the most likely ones being -ve GPH anomalies across the UK with a nearby trough and alternating airstreams; it looks like the UK will start autumn, meteorologically speaking, in the middle of nowhere... as the atlantic fights a timid battle with the continent (had enough of them last winter!)

 

Temperatures likely to be slightly above average generally in the 5-15 day period, but at times slightly below with cool E'lies possible and cool NW'lies likely.

[Summer Sun]

ECM has the low back this morning right at the end of its run

 

 

GFS is no where near as bad though

 

 

The same can also be said for GEM which prefers to build pressure in the end

 

 

So its a case of take your pick this morning with the 3 main longer range models all offering different solutions for the same 3 day period later next week

 

GEM would be my pick of the 3

Edited August 29, 2013 by Summer Sun

[Summer Sun]

Looking at the 00z ensembles and there is a clear rise in uppers for part of next week (Monday to Thursday is the best estimate) after this they fall back but always stay the right side of average so temperatures would always be around average

 

 

Here is the latest summary on the models from Gibby

 

Hi everyone. Here is my report on how I see the midnight outputs of GFS, The Fax Charts, UKMO, GEM, NAVGEM and ECM for today Thursday August 29th 2013.

 

All models show a Westerly flow over the UK albeit fairly slack. Weak fronts are shown by all models to slip SE across the UK over the next 48 hours with a little rain in places but precious little in the South where some warm bright intervals are likely both today and tomorrow. Winds will freshen in the North tomorrow as a deep Low crosses East well to the North sweeping fresher and cooler conditions SE to all areas by the weekend which looks to be a bright and breezy one with some cooler and fresher days and Autumnally cool night's. Early next week looks like seeing High pressure close to the South with warmer and brighter conditions for a time in the South while the North turns more cloudy and breezy with occasional rain.

 

The Fax Charts show a series of troughs moving SE over the UK over the next few days clearing the SE on Saturday with pressure rising strongly over Southern Britain over the weekend before fronts affect the North by the start of next week with High pressure over the South being steadily squeezed away South with cloudier and breezier weather developing overall with some rain in the North. After a cool weekend the South will warm up for a time early next week.

 

GFS has High pressure positioned over the South early in the week with fine and warm weather slowly giving way midweek to Low pressure feeding down from the NW with increasingly breezy and unsettled weather reaching all areas by the weekend in cooler and windier conditions for all. Thereafter the trend is for much more unsettled conditions to persist with rain at times but some drier and brighter interludes too with temperatures close to the September average for all areas.

 

The GFS Ensembles show the weather finally breaking down over the South around the 5th with good support from most members on this outcome. Until then there are five or 6 more days of fine and dry conditions projected for the South while the North sees more changeable conditions up to that point. Once the break occurs rainfall will affect all areas at times with temperatures close to the seasonal average with some blustery winds at times.

 

The Jet Stream currently moving NE towards Iceland moves SE across the North sea at the weekend. It then moves further South in position over the Atlantic with it's flow taking it in the direction of Scotland next week. Late in the period it appears to show signs of splitting with one arm South and one North of the UK but this all looks rather tentative at this range.UKMO today shows a High pressure belt to the South moving away slowly East. In the South dry, fine and still relatively warm conditions would ensue while the North sees more cloud and wind with occasional rain. It looks like this weather would extend further South over subsequent days late next week.

 

GEM today is having none of the turning more unsettled phase and instead shows a cold front clearing South midweek next week when a little rain in the South would be possible before High pressure slides back over from the West to centre over the UK in 10 days time with fine, bright if Autumnal conditions for all by then away from the far NW.

 

NAVGEM shows fine weather up until midweek when Low pressure pushes down from the North late next week with increasingly unsettled conditions developing over most areas.

 

ECM goes for a much more rapid deterioration in conditions after midweek next week with a very deep Autumnal Low taking up residence near NE Scotland by next weekend with rain, showers and gales all featuring over the UK in what would become a very cool feeling spell of weather too in the strong West or NW wind.

 

In Summary the trend remains for a change in the weather around the middle of next week when the South would join the North in experiencing rain at times in brisk Westerly winds as Atlantic Low pressure finally makes more penetration towards Southern Britain on a more Southerly tracking Jet flow than of late. Only GEM bucks this trend this morning with all other output showing this theme to a greater or lesser degree. However, before all this happens there is still a spell of 5-6 days when Southern Britain and at times Northern Britain too can still enjoy some fine and settled weather albeit with slowly declining temperatures than of late.

 

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

Edited August 29, 2013 by Summer Sun

[draztik]

Very quiet in here this morning!

while being a fan of the gem, it really is on its own for the backend of its run, with the anomaly charts pointing to low pressure in this time frame. Either way, a pleasant 5 days as has been stated, esp for Southern regions. The gates leading the Atlantic in appear open after midweek, for the first time in a while.

Edited August 29, 2013 by draztik

[Summer Sun]

Very quiet in here this morning!

while being a fan of the gem, it really is on its own for the backend of its run, with the anomaly charts pointing to low pressure in this time frame. Either way, a pleasant 5 days as has been stated, esp for Southern regions. The gates leading the Atlantic in appear open after midweek, for the first time in a while.

 

Yeah it must be the changing of the guard season again our warm friends are starting to leave us for the next 7 or 8 months depending on what September brings then depending on what next year brings will depend on when they return a few tend to return in March if its looking warm (unlike this years March! god that was a long month worse than December which is normally the month I find drags with the shortest day and Christmas)

 

It will be a few months yet before the bulk of the winter lot come out of hibernation but again that will depend of the conditions if its mild to start winter then It will remain quite if its cold it will be in melt down

 

I always know when its looking cold in winter with-out viewing the thread, if the page count since I last logged on has gone up free-fold its a cold outlook if its only gone up by a few its not looking good for those seeking cold weather. I think it went up about 24 pages over a 10 hour period at times last winter I can only imagine what this place was like at the end of 2010! I bet it was in meltdown

 

Anyway looking at the ECM anomaly it looks decent up-to the 4th but then low pressure is shown to move in bringing the first unsettled spell of Autumn

 

Red is high pressure blue is Low the darker the colors the deeper the pressure is

 

 

 

ECM ensemble

 

 

The ECM Op is probably on the extreme side this morning for the low a watered down one is the most likely outcome with a meet in the middle situation occurring

Edited August 29, 2013 by Summer Sun

[Captain Shortwave]

I think again the ECM has overdone the troughing in the latter stages though I wouldn't be surprised if we got a cooler north/north westerly shot in 10 days time. I expect the low to correct north a little and push eastwards with a bit more intent. I don't buy the low steaming in from the Atlantic and then simply stalling over Scotland. 

In the shorter term there is good agreement for the 12C isotherm to be present over the UK for around 48 hours, and in fact southern areas look fine and potentially very warm next week until a cold front pushes south east next Friday.

Given any real unsettled weather is at day 8 and beyond there is still time for conditions to improve from the 6th September onwards, or of course get worse

[shedhead]

I think again the ECM has overdone the troughing in the latter stages though I wouldn't be surprised if we got a cooler north/north westerly shot in 10 days time. I expect the low to correct north a little and push eastwards with a bit more intent. I don't buy the low steaming in from the Atlantic and then simply stalling over Scotland. 

In the shorter term there is good agreement for the 12C isotherm to be present over the UK for around 48 hours, and in fact southern areas look fine and potentially very warm next week until a cold front pushes south east next Friday.

Given any real unsettled weather is at day 8 and beyond there is still time for conditions to improve from the 6th September onwards, or of course get worse

Agree, wouldn't be the first ECM has gone 'on one' in the later stages this Summer, but some sort of cooler, more unsettled pattern does now look likely to emerge this time next week....unfortunately just in time for my holiday

 

As Draztik said, GEM offers a straw to clutch, with a big, fat high sat right across England and Wales a week on Sunday, but the chances of this or even something similar verifying look slim in the extreme at present. 

 

[Tamara]

There is a computer model minefield in the further outlook with a high chance of them making a complete dogs breakfast over the low depicted for the latter part of next week. It seems reasonable to suggest that our ridge/attempted trough pattern is going to persist and that whatever degree of trough element verifies next week will be followed by another element of ridging, most probably slighly further south thereafter.

 

If one picks the bones through these for suggestions for what any trough may do next week, then there are plenty of them - maybe too many.

Impossible to start to give any detail beyond the weekend other than probably a fair warm start across the south, then some attempt at a more unsettled shot of weather (of some type) and this followed maybe to some kind of renewed split in the weather from NW to SE.

[johnholmes]

Yeah it must be the changing of the guard season again our warm friends are starting to leave us for the next 7 or 8 months depending on what September brings then depending on what next year brings will depend on when they return a few tend to return in March if its looking warm (unlike this years March! god that was a long month worse than December which is normally the month I find drags with the shortest day and Christmas)

 

It will be a few months yet before the bulk of the winter lot come out of hibernation but again that will depend of the conditions if its mild to start winter then It will remain quite if its cold it will be in melt down

 

I always know when its looking cold in winter with-out viewing the thread, if the page count since I last logged on has gone up free-fold its a cold outlook if its only gone up by a few its not looking good for those seeking cold weather. I think it went up about 24 pages over a 10 hour period at times last winter I can only imagine what this place was like at the end of 2010! I bet it was in meltdown

 

Anyway looking at the ECM anomaly it looks decent up-to the 4th but then low pressure is shown to move in bringing the first unsettled spell of Autumn

 

Red is high pressure blue is Low the darker the colors the deeper the pressure is

 

 

 

ECM ensemble

 

 

The ECM Op is probably on the extreme side this morning for the low a watered down one is the most likely outcome with a meet in the middle situation occurring

If you don't mind me being a touch predantic SS, the colours represent height anomalies NOT strictly pressure anomalies at 500mb, the darker the colour the greater the anomaly.

I do agree with your comments about folks arriving and leaving and especially the bit about a cold outlook makes for large page numbers in a short time!

Edited August 29, 2013 by johnholmes

[johnholmes]

Thursday 29 Thursday 29 aug

Ec-gfs

They continue the theme of the upper air becoming dominated by trough rather than ridge, especially again the ec version

I think there is enough evidence to suggest from all 3 now that this will be the pattern by 6-10 days from now. How long, well who knows at this juncture.

 

the ECMWF-GFS output this morning gives the general idea but NOT necessarily the complete and accurate set up.

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

the NOAA two outputs show that both those go along with this trough becoming in charge with +ve heights in the Atlantic and 'possibly' an upper  ridge developing west of the UK.

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

 

the above is likely in the 6-15 day time scale. I've made no attempt to look further although I suspect that pattern, assuming it does become reality, will be with us for a little while beyond the 15 days.

A proviso to the above is that I have not had time to look at other possible complications over the last few days, hurricane issues can and do put a spanner in the most reliable of longer term links over the next 4-10 weeks. When I get time over the weekend I'll take a look there and the same with ENSO, MJO etc.

Edited August 29, 2013 by johnholmes

[No Balls Like Snow Balls]

GFS 06Z

 

The very warm uppers (12+) manage to hold on in the South East until midweek.

 

 

 

But by the end of the week Autumn is here. Hmmm sniff sniff, what is that i can smell?, yep that's right fresh, cool autumn air.

 

 

[tollgateiow]

There is a computer model minefield in the further outlook with a high chance of them making a complete dogs breakfast over the low depicted for the latter part of next week. It seems reasonable to suggest that our ridge/attempted trough pattern is going to persist and that whatever degree of trough element verifies next week will be followed by another element of ridging, most probably slighly further south thereafter.

 

If one picks the bones through these for suggestions for what any trough may do next week, then there are plenty of them - maybe too many.

Impossible to start to give any detail beyond the weekend other than probably a fair warm start across the south, then some attempt at a more unsettled shot of weather (of some type) and this followed maybe to some kind of renewed split in the weather from NW to SE.

Think you might have it spot on Tamara, particularly about a renewed  NW/SE split,latest UMMO 6-15 certainly thinks so too.