Model Output Discussion 1200 hrs 30/09/14

[nick sussex]

Overall we're seeing the outputs pull back from sticking troughing over the UK. Troughing to the west of the UK now looks more favoured, so a slow moving European pattern effected by a complicated USA pattern.

 

The interest increases a little because of the nature of the set up, we have the build of pressure to the east but what happens to our Atlantic trough. Do we get WAA  going north into Greenland by means of a sharper more amplified trough or does the pattern flatten out?

 

Before then however its a complicated affair because of the possible interaction between the main Atlantic troughing and those shallow lows near the UK.

 

The forecast going forward into next week could range from troughing just to the west of the UK, a southerly flow to its east bringing some nice temperatures, any cloud and rain reserved for more western and nw areas.

 

Theres also the possibility of a stronger ridge developing near the UK and helped by that WAA we see this further north, colder air being pulled into Scandi could start creeping towards the UK as we see winds change more to an east/se.

 

For the timebeing I think the more southerly flow is more likely however watch out for the T144 hrs timeframe because a more sharper Atlantic trough and no interaction between that and shallow low pressure near the UK could deliver something more towards the drier and colder scenario.

[IDO]

ECM now at D10 in line with GFS with the Atlantic trough and heights towards Scandi: 

 

The GFS Control is my favourite, HP over the UK from D7-D16:

 

   

 

GFS op goes a bit crazy at the far reaches of FI but is rather lonely compared to the ensembles: 

 

After the rain tomorrow not too many rain spikes for London.

 

So the recent 5-7 days of unsettled weather possibly a blip in the overall settled Autumn pattern rather than the onslaught of the more unsettled seasonal weather? A rather benign relatively dry spell of weather after tomorrow, with low precipitation away from the far west, average temps and little wind. How long the higher pressure lasts, now we have cross model agreement, is the question, and the GEFS are not really conclusive yet on that count.

[ANYWEATHER]

gfs and ecm show unsettled conditions for another week, the gfs more especially shows pressure growing to the east of the uk. At day ten T+240 hrs  both models show a blocking scenario over to the east of the uk.....    

[nick sussex]

gfs and ecm show unsettled conditions for another week, the gfs more especially shows pressure growing to the east of the uk. At day ten T+240 hrs  both models show a blocking scenario over to the east of the uk.....    

The cold pool over western Russia is quite impressive for the time of year. Given the rapid cooling at this time of year over the continent it could get interesting if that mid Atlantic troughing plays ball.

 

Its low risk at the moment, we'll see what happens over the next few days.

[IDO]

gfs and ecm show unsettled conditions for another week, the gfs more especially shows pressure growing to the east of the uk. At day ten T+240 hrs  both models show a blocking scenario over to the east of the uk.....    

 

Looking at the GFS rainfall totals, there does not look like much rain after tomorrow for most, the exception being the west.

 

Rainfall totals at the end of Wednesday:    After D8: 

 

Of course its only one run and can change but  for many just a mm or 2 totals after tomorrow for the following 6-7 days? Not that unsettled for the E/SE/S/Midlands?

[Summer Sun]

10 days out but we have agreement between GFS and ECM both show high pressure over the UK with its centre to our east the main difference is the depth of low pressure to our west GFS 100mb, ECM 965, either way both have the high near enough to settle things down and if this was to happen temperatures would respond quite nicely by day but cold overnight with mist and fog possible

 

Edited October 7, 2014 by Summer Sun

[IDO]

Low confidence but NOAA has it's 8-14 day building a surface high anomaly over the UK:

 

GFS 0z has the slack period till D6, then from D7-10 inclusive, HP over the UK:  

 

Still some uncertainty in the background for the pressure rise after D6 within the GEFS on the London graph, and this has been a very slow trend towards this rise and remains so. But appears to remain doubt as to where the Atlantic trough settles at. I would not necessarily call this pressure rise just yet, though the consistent hi-res runs showing this, probably makes it favourite:

 

   

 

Next 8 days rainfall totals still suggesting relatively dry for most: 

 

GEM also builds the ridge from D7 and at D10 it is holding:  

 

ECM showing ridge around D8, slightly slower than other models: 

 

And by D9 the high is further east so more an influence from the trough, especially for the west: 

 

But that drags some warm uppers in:   D10: 

 

ECM reflective of the variation in the GEFS.

 

 

 

 

 

 

 

 

 

 

[knocker]

Regarding the low confidence with NOAA ido.

 

Although the ECM and GFS anomalies don't agree, the GFS has gone slightly berzerk, the trough in the western Atlantic for one, it does open up the possibilities of dragging in some colder air from Russia.

 

 

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY WEDNESDAY OCTOBER 8TH 2014.

 

NEXT UPDATE THURSDAY OCTOBER 9TH 08:00

 

THE CURRENT GENERAL SITUATION. An unstable West or SW flow covers the UK with a deep Low approaching Western Britain tomorrow.

 

MODELS-2 WEEK HEADLINE  Low pressure easing away North and West with pressure rising later over or to the East and SE of the UK.

 

THE JET STREAM ENSEMBLE FORECAST The Jet Stream is likely to remain positioned well South of the UK for the next 4-5 days while weakening steadily. It then buckles South across the Atlantic and returns in a North or NE flow up the Western side of the UK before settling back to a generally Easterly flow across the heart of the UK by the end of week 2.

 

GFS The GFS operational his morning shows the current deep Low to the West of Ireland moving slowly North and NE filling slowly over the coming days but remaining influential well into the weekend with it's showers and rain at times for all. Pressure continues to gently rise early next week in response to deep Atlantic Low pressure throwing a ridge across the UK and Northern Europe drying things up for many. Later in the run this High declines SE and a SW and then Westerly flow with Atlantic Low pressure running across Northern Britain is shown to return rain and wind at times to all parts later in generally near to average temperatures.

 

THE GFS ENSEMBLES. The GFS Ensembles differ only in small scale synoptics to that of the operational with the resultant conditions at the surface remaining very similar to that of the operational in that after a showery remainder of this week and weekend a brighter and in places warmer period develops as High pressure builds over and then to the SE before a return to changeable weather under a predominantly Westerly flow develops later in week 2.

 

UKMO UKMO this morning shows pressure becoming slack across the UK at the weekend and into the start of next week though with pressure gently rising. Some slow moving coastal type showers are likely but with light winds and some clear spells at night some mist and fog patches could become an issue night and morning.

 

THE FAX CHARTS  The Fax Charts show Low pressure to the West and SW with a complex array of troughs gradually transferring NE over the coming 4-5 days with the main centre lying close to the far North at the weekend as a much weaker feature as pressure rises slowly from the South and pressure becomes slack across the UK.

 

GEM The GEM operational today is broadly similar in the short term before it too develops a deep Atlantic low at the start of next week which sends up a strong ridge to the SE and brings warm SW winds and rain to the North and West before a large High just to the SE extends a ridge through all areas later bringing some unusually warm and bright weather across the South of the UK in particular from Southern Europe in a week to 10 days time.

 

NAVGEM NAVGEM also rises pressure to the SE next week though it is a slow progress. Nevertheless, by the middle of next week all areas become bathed in mild SW winds with any rain becoming restricted to the far North and West with some pleasant October weather developing across the South and East. 

 

ECM The ECM operational shows a more integrated push towards the UK of deep Atlantic Low pressure next week with a deep centre lying not far to the West of Ireland by the end of next week. This pushes the axis of the ridge of High pressure further East and allows a more coherent push of unstable but mild SW winds across all areas with rain at times becoming more extensive too by the end of the run.

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend towards at least a period of drier, warmer and brighter weather is shown by most models next week but there is some disagreement as to what extent and duration this might take.

 

MY THOUGHTS  Having seen GFS lead the way yesterday on a new theme of High pressure based weather yesterday morning and see this extended to later day runs too from many models it has decided to be less dramatic in the form this might take on this morning's output as the Atlantic proves a stronger beast, pushing the developed High to the East and SE next week while eroding it with SW winds and troughs of Low pressure. This theme is also shared by ECM which to be fair showed a similar evolution to this morning's run yesterday morning. It's left to GEM to fly the flag on some unusually warm weather extending North on the Western flank of the European High next week which would give some very pleasant weather in the SE late next week if it evolved as shown. So which is right? I think the carrot will continue to be dangled in upcoming runs on at least the possibility of some unseasonably warm weather towards the SE next week as the large Atlantic Low pressure sets up and brings the warm Southerly flow North. It's then left for the models to pin down the detail on how much the active Low to the West makes inroads into the UK with it's attendant wind and rain and how much of a fight the High to the SE puts up. So the only way to describe things for next week currently is to say that it will definitely become milder than currently for all and possibly warm in the SE. There will be the chance of rain at times too and this will mostly be focused on the North and West in the short term with the caveat that this 'may' spread to other areas too late in the forecast period. It will be interesting to see how the models play around with this deep Atlantic Low and European High over the coming days output with the UK as usual in the battleground between the two.

 

[johnholmes]

Regarding the low confidence with NOAA ido.

 

Although the ECM and GFS anomalies don't agree, the GFS has gone slightly berzerk, the trough in the western Atlantic for one, it does open up the possibilities of dragging in some colder air from Russia.

The 3 main anomaly charts are pretty clear in the 6-10 day range of the upper pattern. Once into the 8-14 NOAA has been slowly shifting its emphasis towards a more settled idea, at least for the se. How far north that extends seems uncertain at the moment.

links below

NOAA

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

EC-http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

I should have added that this morning both EC and GFS, GFS especially, seem to want to develop the ridging and +ve heights over/E of the UK more so than the 6-10 NOAA. Perhaps its issue this evening may support this occurring earlier than it previously predicted?

also the 6 day stats again shows Met in the lead for, I think, the 4th or 5th consecutive day, not that often EC is left in 2nd for so long?

 

http://www.emc.ncep.noaa.gov/gmb/STATS/STATS.html

Edited October 8, 2014 by johnholmes

[carinthian]

Morning, I have been pleased with the UKMO 144hrs model results recently, reasonably spot on. So, again I think this is the model in the shorter term to follow. I would suggest there is still no sign of major zonal Atlantic flow and the rotating cyclonic system affecting much of Western Europe will slowly fill towards the weekend. As there charts show, the UK in no mans land by 144 hour, almost Col positioning as pressure still holding high in the Greenland Sea and the Med, low anchored out west and  over Scandinavia. looks like drying out next week but the longer nights may produce the first widespread fog of the season. I think they will go for about average temps. Beyond that, who knows, but instincts tell me high pressure could dominate again.

 C

[knocker]

The 3 main anoamly charts are pretty clear in the 6-10 day range of the upper pattern. Once into the 8-14 NOAA has been slowly shifting its emphasis towards a more settled idea, at least for the se. How far north that extends seems uncertain at the moment.

links below

NOAA

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

EC-http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

I should have added that this morning both EC and GFS, GFS especially, seem to want to develop the ridging and +ve heights over/E of the UK more so than the 6-10 NOAA. Perhaps its issue this evening may support this occurring earlier than it previously predicted?

also the 6 day stats again shows Met in the lead for, I think, the 4th or 5th consecutive day, not that often EC is left in 2nd for so long?

 

http://www.emc.ncep.noaa.gov/gmb/STATS/STATS.html

 

Certainllythe GFS is much more bullish than the ECM this morning at ten days with the eastern build up of heights and, probably in conjunction, the trough in the western Atlantic giving a much more meridional flow to the jet than the ECM. To my uneducated eye this situation is still in a state of flux.

[vladthemert]

I thinking the recent events in iceland has already effected weather patterns brought about the cold  period earlier and possible spell a colder winter.  

 

noticed GFS has few lows scheduled at present to hit or clip uk in next few days after this one.  one at 162 hrs hits directly at 960 hpa even drops 955 hpa over uk.

[summer blizzard]

I thinking the recent events in iceland has already effected weather patterns brought about the cold  period earlier and possible spell a colder winter.  

 

noticed GFS has few lows scheduled at present to hit or clip uk in next few days after this one.  one at 162 hrs hits directly at 960 hpa even drops 955 hpa over uk.

 

Nowhere near big enough to have such a massive impact.

[knocker]

I thinking the recent events in iceland has already effected weather patterns brought about the cold  period earlier and possible spell a colder winter.  

 

noticed GFS has few lows scheduled at present to hit or clip uk in next few days after this one.  one at 162 hrs hits directly at 960 hpa even drops 955 hpa over uk.

 

Are we looking at the same chart because I've got a low mid Atlantic 975mb with a ridge over the UK?

[carinthian]

Morning, I have been pleased with the UKMO 144hrs model results recently, reasonably spot on. So, again I think this is the model in the shorter term to follow. I would suggest there is still no sign of major zonal Atlantic flow and the rotating cyclonic system affecting much of Western Europe will slowly fill towards the weekend. As there charts show, the UK in no mans land by 144 hour, almost Col positioning as pressure still holding high in the Greenland Sea and the Med, low anchored out west and  over Scandinavia. looks like drying out next week but the longer nights may produce the first widespread fog of the season. I think they will go for about average temps. Beyond that, who knows, but instincts tell me high pressure could dominate again.

 C

Looks like todays forecast from the UKMO has firmed up on a more settled end of Oct into early Nov with temperatures generally above average during the day. So I would assume winds with a southerly component for a time.

C

[Yarmy]

Nowhere near big enough to have such a massive impact.

 

Very off-topic, but the current eruption is the largest anywhere in the world since Pinatubo and the largest in Iceland in something like 140 years. It is effusive rather than explosive though (at the moment) so isn't a headline-grabber. It is, however,  emitting a staggering amount of SO2:

 

http://icelandreview.com/news/2014/09/25/holuhraun-emitting-more-so2-pollution-all-europe

 

But there will soon be little daylight at those latitudes  , so I agree that I can't see it having a major impact (if one assumes that the primary effect is increased sulphate aerosols reflecting solar radiation).  I'm not sure how it would manifest itself in the model output anyway.

[vladthemert]

Are we looking at the same chart because I've got a low mid Atlantic 975mb with a ridge over the UK?

 

sorry GEM 

 

http://www.meteociel.fr/modeles/cmc_cartes.php?code=15&ech=384&mode=0&carte=1

 

ah thanks summer blizzard and yarmy.

 

Yarmy found this Measurements from recent eruptions such as Mount St. Helens, in 1980, El Chichon, Mexico in 1982, and Mount Pinatubo, Philippines in 1991, clearly show the importance of sulfur aerosols in modifying climate, warming the stratosphere, and cooling the troposphere. SO2 converts to sulfuric acid aerosols that block incoming solar radiation and contribute to ozone destruction.  So under this SO2 could cool the troposphere agreed how could models take this into consideration.  Has iceland caused enough to shift weather patterns, I now not sure.

 

 

Edited October 8, 2014 by vladthemert

[gottolovethisweather]

Getting this thread back on-topic, it does seem my "gut feeling" might be starting to show up consistently across the various outputs at least with regard to my patch over the reliable timeframe. Any accurate forecasting possibilities beyond mid-October and more especially into the final third of October carry their usual risks but............ to repeat my quoted sentence.

 

"Gut feeling only but the folk in the SE in particular may well end up wondering what all the fuss is about as the strongest winds and heaviest rain will always be outside of this region. I predict a drier than average month for a England upcoming despite the opening up of the Atlantic at least until a broader more active Atlantic comes knocking with its Ex-Hurricanes in the flow, keep a watch in there in the meantime."

 

Over to the rest of you to analyse the upcoming spell, which could soon see things-a-changing at least for a large part of England with Frost and Fog the day to day weather concerns. The here and now has seen a whole rash of potent rain showers with occasional Thunder in quite broad swathe of West and Central England.

Edited October 8, 2014 by gottolovethisweather

[knocker]

sorry GEM 

 

http://www.meteociel.fr/modeles/cmc_cartes.php?code=15&ech=384&mode=0&carte=1

 

ah thanks summer blizzard and yarmy.

 

Yarmy found this Measurements from recent eruptions such as Mount St. Helens, in 1980, El Chichon, Mexico in 1982, and Mount Pinatubo, Philippines in 1991, clearly show the importance of sulfur aerosols in modifying climate, warming the stratosphere, and cooling the troposphere. SO2 converts to sulfuric acid aerosols that block incoming solar radiation and contribute to ozone destruction.  So under this SO2 could cool the troposphere agreed how could models take this into consideration.  Has iceland caused enough to shift weather patterns, I now not sure.

 

 

 

Yes that is well known but  result from major explosive eruptions forcing SO₂ into the stratosphere whence it travels around the world.

[Yarmy]

Yes that is well known but  result from major explosive eruptions forcing SO₂ into the stratosphere whence it travels around the world.

 

Yes, causing a temporary cooling on a global scale. Since we don't have an explosive eruption in Iceland, one might not expect the molecules to reach high enough into the atmosphere. However, CFCs are also heavier-than-air molecules and as we know they had no trouble penetrating the stratosphere to devastating effect through the normal atmospheric motions. 

 

We are wayyyy off-topic.

[knocker]

Not really, consideration is being given to the NASA GEOS-5 Aerosol Model Forecast

[phil nw.]

Let,s keep on topic,ie models please chaps.

Ta.

[Summer Sun]

UKMO continuing to hint at something more settled than of late developing as we move into next week

 

 

Temperatures should be around or slightly below average to start next week by day and colder overnight with mist and fog patches developing it could also be frosty in some northern parts depending of course on cloud cover

 

[IDO]

The GFS op and Control interestingly, via different routes end up with a HP dominated FI for the UK:

 

Op at T348:   Control at the same time: 

 

However the upper flows are different, op:  Control: 

 

The GEFS favour the warmer flow.

 

Anyway for the next four days we have the LP system retreating NE and filling so showers should become less prevalent and less potent: 

 

Then follows 3-4 days of a slack flow that should keep most of the UK dry as the low deepens to our west: 

 

It slowly edges NE so by D9: 

 

Subtle differences to this general flow on the GEFS. GEM marries this scenario but the LP system a bit further north and by D10 GEM:

 

 

The GFS op and control build heights over the UK at different time scales (Control not till T300, op at T240).

 

No real consensus amongst the ensembles, so FI output very uncertain. Just a shame some of the synoptics we are seeing now are not two months down the line.