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Model Output Discussion - 31/8/14 Onwards.


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Posted
  • Location: Camborne
  • Location: Camborne

    A quick glance at the 18z GFS en passant and it would appear to be moving towards a transition.  There is weakening of the Iberian trough and a build up of heights in the western Mediterranean ridging into southern Europe. By Monday the trough has disappeared with a major trough western Atlantic. Still quite warm but less so than Friday.

     

    GFS 00z ops

     

    A quick glance and the anomalies are a tad bizarre. It has the Iberian low marching south west and introduces a small enclosed shallow low Stornaway which travels south east to the North Sea in the next 24hours while the IB low continues to disappear.

     

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    Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

    Its a case that anything after D6 is very speculative. Just looking at the models at D6 highlights the uncertainty as to the track and strength of the tropical storm: (TS)

     

    GEM:post-14819-0-42941400-1410588968_thumb.p  GFSpost-14819-0-72158400-1410588981_thumb.p

     

    UK: post-14819-0-63569000-1410588996_thumb.g  ECMpost-14819-0-07163100-1410589773_thumb.g

     

    At the moment the most likely outcome from this TS is that it will temporarily disrupt the Azores Atlantic ridge as it stalls when it runs into the Atlantic ridge. The ridge is then replaced with a trough and higher heights should build on the eastern flank, close to the UK. The GEM at D10 is the most smooth evolution:

     

    post-14819-0-77292000-1410589929_thumb.p  The GFS op hints at this but s a much quicker transition: post-14819-0-86248100-1410590071_thumb.p

     

    However the GEFS mean leans more towards the GEM's slower track of the TS so the associated ridge is more apparent at D10: post-14819-0-57795800-1410590169_thumb.p

     

    ECM also slower progression and by D9: post-14819-0-51594200-1410591020_thumb.g

     

    All interesting but pure guesswork at the moment. In the short term as the models have been hinting at for a while with the friendly placement of the upper low to the SW we are going to get a plume from around D4 for around 3 days (+12c uppers for the south on GFS):

     

    post-14819-0-01344100-1410590526_thumb.p  post-14819-0-46810400-1410590536_thumb.p 2m temps London: post-14819-0-10169100-1410590556_thumb.g

     

    Variations as to intensity and longevity cross model though.

     

    Should be some convection with that sort of flow. Remaining dry before then with just above average temps for most.

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    Just a thought about those NOAA anomaly forecasts.

    On those anomaly charts the signal for change in week 2  is less obvious .The second image is after all only an average spread of the pattern through days 8-14.

    If we refer again to the daily mean charts from around day 9/10 onwards it's much clearer that the Scandinavian ridge moves away as the pattern changes further on to a westerly.

    Just one of the reasons to best view those anomalies in conjuction with the daily mean charts to clarify the general trend towards any changes. 

    Sometimes there are only subtle changes to those wavelengths and positioning(green Contours) from one to the other, especially when the anomaly differences are small as they are currently.

     

    your post is very true phil, I never take any set of charts from one source without looking at how they relate to other outputs, although I rarely make any comment about any other set of data. The anomaly part is just one part of the information with the predicted contour pattern being at least as important as what any anomaly shows especially if it is lower than 60dm. Be that + or -. The main feature in the 8-14 set of charts over the past week is how the trough, to the west or initially SW of the UK, has been smoothed out with a more general flow from a more westerly point at 500mb being predicted. Apart from the Tropical Storm possibly upsetting the apple cart that would seem to be the most likely upper air pattern in the current 8-14 day time frame I think.

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    Posted
  • Location: Camborne
  • Location: Camborne

    As ido mentioned next weekend is up in the air at the moment. The ECM ops doesn't retreat the Iberian low as much as the GfS. It does build the ridge central Atlantic and moves it east with a SW/NE orientation. On the surface the UK, mainly the south still influenced by slack low pressure and the temps around average but at this stage discussing the temperature and weather  is rather pointless speculation given the somewhat fluid analysis and lack of agreement. The GFS has Edouard ending up near Iberia!

     

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    Posted
  • Location: Catchgate, Durham,705ft asl
  • Location: Catchgate, Durham,705ft asl

    The fax chart for Monday would be much more exciting if it were January,unfortunately in September it looks like a drizzle-fest for central and northern areas.

     

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    Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

    I think there is as much chance of another scandi block than a westerly flow in week 2. Whatever transpires, patterns look to remain slack.

    Agreed on that, there is definitely the possibility of that tropical storm giving the Azores high enough of a kick north eastwards that it could hop over the Iberian low and build over or to the north east of the UK.

    ECM1-240.GIF?13-12

    gem-0-240.png?00

    As others have said the ECM and GEM operationals are quite keen on this idea.

    Still given the existence of this tropical low then I think any run beyond around 5 days out should be taken with a pinch of salt.

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    Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

    Looking at UKMO this morning the low to the west of Portugal doesn't look like it will have much impact on the UK

     

    Rukm961.gifRukm1201.gifRukm1441.gif

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    Posted
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)

    Oh it will Gavin by dragging up warmer se winds and with the chance of thundery showers later next week!

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    Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

    Fairly good agreement from the GFS/GEM and UKMO up to day 6

    gfs-0-144.png?12

    UW144-21.GIF?13-18

    gem-0-138.png?12

     

    A moderate at first east to south easterly, becoming slacker and increasingly warm from mid week with temperatures reaching the mid twenties in the south. Good agreement on the track of the storm heading towards the Azores, this is a pretty good ticket for the Azores high to be displaced towards the UK. Looks like cold air could spill into the Atlantic too which could reinforce the current pattern. 

    Edited by Captain shortwave
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    Posted
  • Location: Keyingham, East Yorkshire
  • Weather Preferences: Spanish plumes, hot and sunny with thunderstorms
  • Location: Keyingham, East Yorkshire

    Next weekend is shaping up rather good if the GFS 12z is correct with warm air over the UK and winds dropping resulting in some very warm temperatures likely. Low to mid 20s for the Midlands and southern England with some lingering mist and low cloud likely over eastern areas. Considering how the breakdown has continued to be pushed back, one cant call anything beyond next weekend.

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    Posted
  • Location: Manchester
  • Location: Manchester

    Indeed Milhouse, the GFS is even showing 27C in the South for next Saturday- it's still a long way off but it looks increasingly likely that temperatures will rise towards the end of the week and into the weekend with a southeasterly setting up.

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    Posted
  • Location: Camborne
  • Location: Camborne

    The ECM ops appears to be the odd one out. It's not going for very high temps for the weekend simply because it has the upper high and surface high to the NW of the UK thus of course the airflow becomes easterly. The sequence although I suspect the ens may differ.

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    Edited by knocker
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    Posted
  • Location: Hampton, Evesham, Worcestershire. 27m asl.
  • Weather Preferences: Extreme and Exciting weather, hate stratus clouds and drizzile
  • Location: Hampton, Evesham, Worcestershire. 27m asl.

    It looks as though some areas of the uk will keep things dry for at another week at least. Models, including the met office updates have been really useless in there short to medium forecasts. Models have made a mockery of forecasting unfortunately. The tropical storms in the Atlantic have really given the models a picticular headache this year. Its going to take someting the other side of the pond to at last give the jet stream a kick to the Uk. Nothing to suggest that for now, but of course its just a matter of time..........

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    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

    This is a nearly perfect scenario for drawing up late summer heat

     

    ECM1-144.GIF?13-0

    Low pressure off Portugal influencing us, with no other low pressure influence, meaning we are the northern-most point of the circulation, and everything is coming from our south. All that's missing for a really hot blast is better heights over Central Europe, which would tighten the isobars dragging up the warmer air quicker and giving a drier feed too. As it is, pretty good for warmth in September, but we still may see 24C/25C as the temperature ceiling due to the slack air and possibility of a thundery influence preventing nice blue skies.

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    Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

    It looks as though some areas of the uk will keep things dry for at another week at least. Models, including the met office updates have been really useless in there short to medium forecasts. Models have made a mockery of forecasting unfortunately. The tropical storms in the Atlantic have really given the models a picticular headache this year. Its going to take someting the other side of the pond to at last give the jet stream a kick to the Uk. Nothing to suggest that for now, but of course its just a matter of time..........

     

    Agree we seem to be at the mercy of the tropical storms at the moment - waiting to see what they do, thanks to a very quiet 'atlantic' in the main, however, traditionally the atlantic gets its act together later in September thanks to a resurgent Polar vortex, this year it seems to have gone to sleep for a lengthy period, unsure what to do, allowing these tropical features to dictate affairs, but as you say only a matter of time that we see the PV become the major player in our weather , the early plunge of cold into mid lattitudes over north America likely to fuel the PV into action as we see a steeper temp gradient develop over the coming 2 weeks.

     

    Until then - its a dry outlook for many, unusually so for the NW of the quarter, another week of quiet weather.. four dry weekends in a row now here..not often you can say that in the Lake District! can we make it 5?

    Edited by damianslaw
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    Posted
  • Location: Camborne
  • Location: Camborne

    The GFS and ECM don't agree on the analysis for the weekend. The upper anomalies have a different orientation giving a different interpretation on the surface. The GFS has the HP more to the north and give more emphasis to the slack low pressure area to the SW thus allowing an more southerly air flow over the UK. The ECM on the other hand has the surface HP more to the NW drifting SE cutting off the southerly flow resulting in still warm but lower temps.

     

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    Posted
  • Location: Camborne
  • Location: Camborne

    Agree we seem to be at the mercy of the tropical storms at the moment - waiting to see what they do, thanks to a very quiet 'atlantic' in the main, however, traditionally the atlantic gets its act together later in September thanks to a resurgent Polar vortex, this year it seems to have gone to sleep for a lengthy period, unsure what to do, allowing these tropical features to dictate affairs, but as you say only a matter of time that we see the PV become the major player in our weather , the early plunge of cold into mid lattitudes over north America likely to fuel the PV into action as we see a steeper temp gradient develop over the coming 2 weeks.

     

    Until then - its a dry outlook for many, unusually so for the NW of the quarter, another week of quiet weather.. four dry weekends in a row now here..not often you can say that in the Lake District! can we make it 5?

     

    Sorry I'm afraid that is lost on me. Perhaps a little explanation on how this fuelling of the PV works if you don't mind? The current 200mb level chart.

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    Posted
  • Location: Camborne
  • Location: Camborne

    This mornings GFS has slightly altered it's position vis a vis the weekend.

     

    Friday

     

    Low 1000mb Biscay with HP NW of Ireland. Winds mainly SE over England  Temps in the SE mid 70s F but much lower in the north and west.

     

    Saturday

     

    Low now 1004mb with the HP 1025mb just north of Stornaway tending to influence all of the UK apart from the south,  Temps low to mid 70s in SE but lower elsewhere and quite chilly in Scotland with temps hovering around the 60sF

     

    Sunday

     

    HP now north North Sea and influencing the whole of the UK. Temps low 70S in the SE but low to mid 60sF elsewhere.

     

    TS 93L

     

     

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    Edited by knocker
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    Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

    There still remains uncertainty with regard to the tropical storm and its interaction with the Atlantic ridge and the lower heights to the NW. GEM remains intent on linking it with the lower heights and pumping up the resultant Atlantic trough:

    D7: post-14819-0-32878700-1410676536_thumb.p D9: post-14819-0-56389100-1410676554_thumb.p

    The GFS at the same time has a ridge blocking that link up: post-14819-0-60333200-1410676657_thumb.p post-14819-0-52117300-1410676680_thumb.p

    The storm then fizzles out as it sinks south (Azores). The GFS op then continues with the current pattern of slack areas of low and HP meandering around our part of the NH with seemingly little impact from this storm. So by D10:

    post-14819-0-71357900-1410676830_thumb.p

    GFS in FI has been for a while been invigorating the PV and again this is apparent on this run: post-14819-0-75521000-1410676906_thumb.p

    If that is the case a return to a westerly zonal flow looks inevitable. Where the jet settles at could mean a N/S split. Too early to have confidence in this.

    Of course the above two are just two options as it remains fluid. For instance the GFS Control sends the storm to the SW as a cut off low/trough and this enables the Azores to ridge into the UK for 5 days plus:

    D10 post-14819-0-96011200-1410677184_thumb.p D16 post-14819-0-62455900-1410677193_thumb.p

    This keeps the jet further north and UK wide more settled.

    ECM mixes the tropical storm with the low currently in situ to the SW and by D9 we have the UK within the boundary of slack areas of an upper trough and upper ridge:

    post-14819-0-06662200-1410677490_thumb.g

    Lots going on and no resolution to post TS Edouard.

    GEM and GFS are still showing from D4 around 3-4 days of warmer uppers for the south (>+12c) whilst ECM now downplaying that. Showers in week 1 rather than anything too wet. Looking more likely that the Atlantic will be held back for most of September though signs are that changes late Sep/early Oct are now being signalled.

    Edited by i'm dreaming of...
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    Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

    UKMO shows a slow return to high pressure by next weekend

     

    U96-21UK.GIF?14-07U120-21UK.GIF?14-07U144-21UK.GIF?14-07

     

    Although some rain is likely during the coming week it looks limited and patchy the greatest risk of some heavier showers looks likely tomorrow in the east

     

    Temperatures tomorrow look like ranging from the mid teens in northern England to the low 20's in the south, for the rest of the week temperatures will range from the high teens in northern England to the mid 20's in the south.

     

    Night time temperatures should hold up well in the towns and cities for the coming week 13c to 16c

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    Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

    If GFS is right the summer like warmth isn't done just yet for the south

     

    Into the mid 20's on Wednesday

     

    ukmaxtemp.png

     

    Maybe 27c or 28c for some spots on Thursday, Friday & Saturday in the south any showers look very isolated

     

    ukmaxtemp.pngukmaxtemp.pngukmaxtemp.png

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