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Model Output Discussion - 17th Oct Onwards


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Posted
  • Location: Ireland
  • Location: Ireland

    Not surprised to see this output from the 18Z. About half of the 12Z ensembles were showing a strong low taking a track like this, and most of those that did looked more intense than this 18Z operational run, so I wouldn't be surprised if the 0Z threw up something a little more severe again.

    Edited by radiohead
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    Posted
  • Location: UK/ EU resident in Almeirim de Fazendas, Portugal
  • Location: UK/ EU resident in Almeirim de Fazendas, Portugal

    The trend, excepting the depth and track of the low Sunday/Monday, has been increasingly picked up and become consistent over the last few days or so by the the models for the polar vortex to decisively strengthen seasonally and organise itself as it migratrates more centrally/west of the pole with its first major salvo of the autumn. The Canadian side of the arctic becomes involved in this way, much as described recently, so that the pacific jet stream engages a high thermal gradient of cold arctic air as it exits stateside into the atlantic and meets the humid, warm and moist sub tropical flow that has been dominating over much of the UK and NW/Central Europe section of the NH of late.

     

    Some modelling, f.e the GEM Canadian model, first picked up this potential cyclogenesis of mixed cocktail of airstreams meeting together back last weekend when the modelling was in the FI 8 to 10 day range. Picking such deep lows is impressive at face value at such a range of modelling in terms of usual applied reliability that far out..but we should remember that the models handle (in general) this type of fast paced atlantic jet stream pattern better than blocked patterns. And we haven't seen such an invigorated pattern modelled for some considerable time.

     

    Little point in adding too much more about the deep low itself for Sunday/Monday than already spoken about so much - but it needs watching closely obviously and the track, as suggested by the ECM on both outputs today, is actually reasonably supported by the latest EPS members..and could be increasingly concerning and problematic IMBY if this track becomes more widespreadly agreed. The channel could become the difference between a cyclonic col with the wind field displaced into Northen France (not wishing it on them per se obviously) or quite a disruptive/damaging wind storm as a worst scenario if the cyclogenisis is as rapid as some of the solutions suggest and the track is further north through southern/central UK with the strongest winds on the southern flank of the low. Notwithstanding what was said at the start of this post, the chances still remain that much as seen before on previous occasions, the storm might not evolve and remain a more open wave type secondary feature, but the worst case scenarios are also clear enough to see amongst the ensemble members and I wouldn't them to become realityPosted Image

     

    Posted Image

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    Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

    At last we have exciting weather to talk about, the models are showing proper october weather ahead of us..just in time for november. :-)

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    Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

    Is a southerly tracking storm coming????  Let's hope so....OK...likely max gust location?  I'm going for Mumbles Head at 90mph

     

    BFTP

    Edited by BLAST FROM THE PAST
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    Posted
  • Location: caernarfon(gwynedd)
  • Location: caernarfon(gwynedd)

    Is a southerly tracking storm coming???? Let's hope so....OK...likely max gust location? I'm going for Mumbles Head at 90mphBFTP

    Why are you hoping bftp? Is it regarding trends for winter?
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    Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

    Why are you hoping bftp? Is it regarding trends for winter?

    No, trends for autumn, it seems generally on track and projected on track.  Winter is a toughie, I'm either with RJS or very different...I think he could..that's 'could'... be wrong and i'm not jumping yet...as there is lot's to be sorted.......and October in UK proves NOTHING!

     

    BFTP

    Edited by BLAST FROM THE PAST
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    Posted
  • Location: OSLO, Norway
  • Weather Preferences: Snow, Storms, Heat, Thunderstorms
  • Location: OSLO, Norway

    Early days yet but at 192 of the GEFS 8/21 pertubations bring a return to northern blocking with some ridging to Greenland, one to watch?

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    Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

    All I want is some snow and frost this winter, hopefully that's not too much to ask for. In the meantime the models are looking good for a lot more rain, gales and even a risk of severe weather..and temperatures much lower next week.

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    Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

    Looking through today's GFS ensembles, for next weeks storm, we can see the mean pressure has dropped on each run for central Southern England, now down to 984mb while the mean wind speed has risen. Obviously the means are not a useful tool for predicting the probable strength of any storm should it materialise but they are useful for probability forecasting.

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    Posted
  • Location: Weardale 300m asl
  • Weather Preferences: Snow
  • Location: Weardale 300m asl

    I hope France doesn't pinch this low again, of course I don't like to see anyone hurt but we've not had a good storm in the southern uk in years, I like storms when people take head and stay where it's safe....I'm not going to have any nails left come Sunday night!Does anyone know what the sustained wind speeds and gusts could be in the southwest (Devon) worst case scenario....how do people see this panning out?

     

    Oops... could be misconstrued, I think you meant 'heed'.

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    Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

    All eyes Sunday into Monday. The exact track of the low is uncertain and this will be very important. Certainly damaging gusts around the low. So all eyes on the models the next few days.

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    Posted
  • Location: Headington,Oxfordshire
  • Weather Preferences: Snow
  • Location: Headington,Oxfordshire

    Here is what the overnight runs have made of mondays potential distruptive storm. 

     

    00Z GFS.

    post-15543-0-58974100-1382593228_thumb.p post-15543-0-73404900-1382593252_thumb.p

     

    00z GEM- Not as bad as previously modelled.

    post-15543-0-82443600-1382593303_thumb.p

     

    00Z UKMO-

    post-15543-0-44884200-1382593367_thumb.g

     

    HR GFS. showing these wind speeds for 7am and 2pm on Monday. Very Very strong winds in Channel moving into North Sea by afternoon. Gale force winds inland with heavy rain.

     

    post-15543-0-52936100-1382593422_thumb.g post-15543-0-96821600-1382593429_thumb.g

     

    post-15543-0-11995200-1382593482_thumb.g post-15543-0-92664300-1382593495_thumb.g

     

    Pressure showing as-

     post-15543-0-53200700-1382593607_thumb.g post-15543-0-65903900-1382593618_thumb.g

     

    Main centre of low over to the Wales area through early hours before cutting across the Midlands and through the Wash late morning before clearing into the North Sea.

    Edited by Mark N
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    Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

    It's going to be an interesting weekend model watching that's for sure ! 

     

    Posted ImagePosted Image

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

    ECM/GFS/UKMO broadly agree on a similar track up the Bristol Channel through the country and leaving into the north sea just north of the Wash

    Posted Image

     

    Posted Image

     

    Case of joining the dots for the ECM here but it's a similar track to the other two.

    GEM shows the low being a total non event and just wind and rain, but nothing of real note

    Posted Image

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    Posted
  • Location: Ireland
  • Location: Ireland

    0Z ECM at 96 hours has developed the low in the same position as the 0Z GFS at 90 hours. A track that would take it over the UK.

     

    The ECM has the low at 980mb at that point, GFS has it at 988mb.

     

    GFS :

    Posted Image

     

    ECM :

     

    Posted Image

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    Posted
  • Location: Rochester, Kent
  • Location: Rochester, Kent

    GFS operational still puts low on a track straight across Britain with significant wind,

     

    post-5986-0-64874300-1382596098_thumb.gipost-5986-0-95471200-1382596105_thumb.gi

     

    GEFS mainly holding firm,

     

    post-5986-0-92993100-1382596151_thumb.gi

     

    With the lowest member at 966hPa, the highest member at 1003hPa, and the mean at 987hPa: this is indicative that most members favour a higher than the mean pressure than lower.

     

    GFS ensemble cluster analysis, is far from helping out on certainty, this morning, with the best cluster representative of only 30% of the ensemble set,

     

    post-5986-0-13286700-1382596261_thumb.gi

     

    And, of course, the associated dendrogram,

     

    post-5986-0-59730100-1382596280_thumb.gi

     

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    Posted
  • Location: Birmingham (Solihull), West Midlands
  • Weather Preferences: Sunshine, thunder, hail & heavy snow
  • Location: Birmingham (Solihull), West Midlands

    It's amazing that the GEM was one of the models who had often kept showing a deep, intense, Low, and now it's decided to drop the idea. GEM must be really bored or something...

    I suppose nothing should be completely ruled out yet in regards to Monday's Low and possible wind and rainstorm (with changes to the intensity and the exact timing of the Low still liable to some alterations).

    Edited by DiagonalRedLine
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    Posted
  • Location: Essex, Southend-On-Sea
  • Weather Preferences: Warm, bright summers and Cold, snowy winters
  • Location: Essex, Southend-On-Sea

    It's amazing that the GEM was one of the models who had often kept showing a deep, intense, Low, and now it's decided to drop the idea. GEM must be really bored or something...I suppose nothing should be completely ruled out yet in regards to Monday's Low and possible wind and rainstorm (with changes to the intensity and the exact timing of the Low still liable to some alterations).

    We also have the fact that when it arrives it could be different
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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    The Fax chart is most likely to have the closest to what the actual track is, it will no doubt change at least slightly from its current track but still the nearest to the trackI would suggest.

    Wind strengths should be reasonably well known by early Saturday but rainfall amounts may take a little longer to get closer to the actual falls. Wind looks the main hazard from the Sunday-Monday low and over souther areas of the UK, chiefly southern England and possibly south Wales.

     

    http://www.netweather.tv/index.cgi?action=fax;sess=

    Edited by johnholmes
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    Posted
  • Location: Longwell Green, near Bristol
  • Weather Preferences: Storms, Gales, frost, fog & snow
  • Location: Longwell Green, near Bristol

    GEFS 0z Mean windspeed diagrams for South West England shows mean windspeeds peaking at around 55mph with some perbs going as high as 90mph;

    post-12721-0-90189400-1382599153_thumb.j

    Hold on to yer hats Cornwall!!

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    Posted
  • Location: Rochester, Kent
  • Location: Rochester, Kent

    GEFS Analysis, Heathrow,

     

    post-5986-0-94584700-1382599827_thumb.pn

     

    Essentially, given GEFS model output, the actual hPa values will lie between the dotted lines some 68% of the time. The closer the dotted lines are to either the high or low shows the skew of the ensemble. So, if the top dotted line is close to the red line, it shows that the ensemble was skewed towards higher pressure.

    Edited by Sparkicle
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    Posted
  • Location: bingley,west yorks.81 absl
  • Location: bingley,west yorks.81 absl

    Fascinating model watching in the Short,medium and long term trends for me,also nice to see Fergie re-surfacing for the autumn/winter shift lol.Keep up the good work all,appreciate it.

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