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Model Output Discussion - 17th Oct Onwards


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

    Not discounting anything, I think at this stage the worst thing about this potential storm is the ground already saturated in many parts of the country

    and the risk of possible flooding near rivers - also the odd branch being snapped off some trees which happens most years in many parts of the UK anyway. Nothing we haven't seen before but judging by some of the papers and hysterical flapping in news you wouldn't think it! 

     

    I suspect there will be more than 'the odd branch snapped of some trees' unless the models have it very wrong and also the Fax chart is way out? Wind will be the major hazard in my view. There may be some flooding but the speed it is moving it is more likely to be very temporary surface water rather than any major river overflow problems.

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    Posted
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL
  • Weather Preferences: Dry/mild/warm/sunny/high pressure/no snow/no rain
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL

    I don't think major flooding is a big risk with this. Yes, heavy rain for sure, but it's not going to hang around!

     

    Haha who said "major" flooding? sure rivers may well go over their bank but I'm not talking about like what we seen in the Lake District in 2009 - it won't take much heavy rain for rivers to swell even more after the prolonged unsettled spell that we've had. I live near a river and it's rather high now.

    Edited by Gaz1985
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    Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

    This looks like its going to be a short lived nasty low with it pulling away quite quickly

     

    06z Monday

     

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    18z Monday

     

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    By t120 its the clam after the storm

     

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    Rainfall totals to 18:00 Monday

     

    Posted Image

     

    I think the potential for surface water flooding is quite high but no major flooding at this stage

    Edited by Summer Sun
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    Posted
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL
  • Weather Preferences: Dry/mild/warm/sunny/high pressure/no snow/no rain
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL

    I suspect there will be more than 'the odd branch snapped of some trees' unless the models have it very wrong and also the Fax chart is way out? Wind will be the major hazard in my view. There may be some flooding but the speed it is moving it is more likely to be very temporary surface water rather than any major river overflow problems.

     

    I guess any strong wind will be very temporary then John? they usually go hand in hand in a weather system. Until a Red warning is on the Met Office warnings then this isn't (at the moment) anything severe.

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

    The wind may well be a feature for somewhat longer than the rain, even short lived gusts of 70+mph can do a good deal of damage in the areas that are most at risk. Indeed it is the gust factor often rather than the mean speed which is the damaging part.

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    Posted
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL
  • Weather Preferences: Dry/mild/warm/sunny/high pressure/no snow/no rain
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL

    The wind may well be a feature for somewhat longer than the rain, even short lived gusts of 70+mph can do a good deal of damage in the areas that are most at risk. Indeed it is the gust factor often rather than the mean speed which is the damaging part.

     

    Where does it say it might be 70+mph gusts especially inland? perhaps out in the English channel? damage to waves most likely then lol.

     

    GFS going for 70+ mph gusts out in English channel, we'll see if the inland speeds update tomorrow onwards. Looks like only a small part Kent might be worst off in all this - the far Eastern tip, maybe Isle of Wight. But for most of us it's just very windy but not terrible. In all honesty though I'll wait for the Met Office to upgrade their warnings before I can be 100% sure, we all know GFS "over-do's" these lows aswell.

     

    Posted Image

    Edited by Gaz1985
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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    Perhaps my phrasing was not the best? I used 70+mph as an illustration of possible damage I did not say winds inland would reach that level. It is quite likely, say 60% risk, those gust speeds will be reached on exposed coasts in the far south and possibly the Channel Isles as far as we can tell from the models at the moment. Until Saturday then neither the actual track, its depth and consequently the wind speeds will be subject to changes in the models. Beyond then the models will be pretty identical I would expect therefore far more confidence will be able to be given on just where the worst winds will occur..

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    Posted
  • Location: Sowerby Bridge, West Yorkshire
  • Weather Preferences: Click on my name - sorry, it was too long to fit here......
  • Location: Sowerby Bridge, West Yorkshire

    As soon as you get to the mid fifties in mph you are looking at trees being uprooted and likely structural damage (as says the Beaufort scale). There should be real concern in the channel islands and some coastal areas in the south, especially for the former with the suggestion of persistent winds at that force and gusts up to hurricane force.

    Edited by ukpaul
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    Posted
  • Location: South Staffordshire
  • Weather Preferences: Snow
  • Location: South Staffordshire

    It seems Monday has taken all the attention, when in reality tommorrow looks a very wet day indeed. Mix that with showers over the weekend and Monday's low, then I think Flooding could be a larger threat than people have considered so far. Hopefully not. 

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    Posted
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL
  • Weather Preferences: Dry/mild/warm/sunny/high pressure/no snow/no rain
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL

    Perhaps my phrasing was not the best? I used 70+mph as an illustration of possible damage I did not say winds inland would reach that level. It is quite likely, say 60% risk, those gust speeds will be reached on exposed coasts in the far south and possibly the Channel Isles as far as we can tell from the models at the moment. Until Saturday then neither the actual track, its depth and consequently the wind speeds will be subject to changes in the models. Beyond then the models will be pretty identical I would expect therefore far more confidence will be able to be given on just where the worst winds will occur..

     

    True John so I think at this stage it may only be a small part of the UK that might be affected, although who knows even there it may get downgraded or maybe more of us could effected. The track is still uncertain, I guess we will know better by the end of Saturday.

     

    As soon as you get to the mid fifties in mph you are looking at trees being uprooted and likely structural damage (as says the Beaufort scale). There should be real concern in the channel islands and some coastal areas in the south, especially for the former with the suggestion of persistent winds at that force and gusts of hurricane force.

     

    Trees won't be uprooted with 55mph gusts, minor structural damage to fences etc yes, we have winds of 55mph every year up here but we don't have uprooted trees, that only happens in 70-80 mph gusts.

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    Posted
  • Location: Between Sidmouth and Exeter
  • Location: Between Sidmouth and Exeter

    I guess any strong wind will be very temporary then John? they usually go hand in hand in a weather system. Until a Red warning is on the Met Office warnings then this isn't (at the moment) anything severe.

     

     

    I don't really understand that statement, considering the amber warning has the highest impact level (just a lower probability hence it's amber not red) there is definitely the potential for a severe event. Though the warning mentions gusts up to 80mph rather than 70mph.

     

    Also about flooding, last year there were several flood events in the SW in Autumn and Winter, not one of those were red warnings, usually orange warnings and often closer time-frames, but the flooding could be described as severe, with the river Exe (amongst others) reaching it's 2nd highest level recorded since gauging stations opened in the 50s/60s, and the highest on record closer to Exmoor. This suggests you don't need a red warning (esp 4 days out!) to potentially get a 'severe' event.

     

    I think with this low, the main wind threat may be south of the main rainfall threat, with the highest accumulations slightly north of the low center perhaps where the rain band becomes slower moving as it pivots. The main wind threat is likely to be sightly further south and could well be the main story

     

    It looks likely to be either pretty wet and perhaps breezy across the south, or be wet for a while as the rain band goes through then very windy/stormy. With the latest GFS and the UKMO being a bit deeper and further north, I'm thinking the 2nd option is perhaps more likely at the moment.

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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

    Mmmm Great difference between GFS and UKMO and where the damage will occur. France Channel Isles or Midlands Southwards. Who's be a forecaster right now. Actually no such a huge difference when I look again. Probably due to gfs going in 3 hourly steps rather the UKMO 24hr step at that point. So we can't actually see when it turns NE in the UKMO. Looks like I'll have to content with possible 50mph gusts this weekend and a bit more rain..

    Apart from that sadly plenty mild on the charts still. 

    Edited by The PIT
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    Posted
  • Location: Sowerby Bridge, West Yorkshire
  • Weather Preferences: Click on my name - sorry, it was too long to fit here......
  • Location: Sowerby Bridge, West Yorkshire

    True John so I think at this stage it may only be a small part of the UK that might be affected, although who knows even there it may get downgraded or maybe more of us could effected. The track is still uncertain, I guess we will know better by the end of Saturday.

     

     

    Trees won't be uprooted with 55mph gusts, minor structural damage to fences etc yes, we have winds of 55mph every year up here but we don't have uprooted trees, that only happens in 70-80 mph gusts.

     

    ...."as says the Beaufort scale".

     

    Force 10 "Trees are broken off or uprooted, structural damage likely."

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    Posted
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL
  • Weather Preferences: Dry/mild/warm/sunny/high pressure/no snow/no rain
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL

    I don't really understand that statement, considering the amber warning has the highest impact level (just a lower probability hence it's amber not red) there is definitely the potential for a severe event. Though the warning mentions gusts up to 80mph rather than 70mph.

     

    Also about flooding, last year there were several flood events in the SW in Autumn and Winter, not one of those were red warnings, usually orange warnings and often closer time-frames, but the flooding could be described as severe, with the river Exe (amongst others) reaching it's 2nd highest level recorded since gauging stations opened in the 50s/60s, and the highest on record closer to Exmoor. This suggests you don't need a red warning (esp 4 days out!) to potentially get a 'severe' event.

     

    I think with this low, the main wind threat may be south of the main rainfall threat, with the highest accumulations slightly north of the low center perhaps where the rain band becomes slower moving as it pivots. The main wind threat is likely to be sightly further south and could well be the main story

     

    It looks likely to be either pretty wet and perhaps breezy across the south, or be wet for a while as the rain band goes through then very windy/stormy. With the latest GFS and the UKMO being a bit deeper and further north, I'm thinking the 2nd option is perhaps more likely at the moment.

     

    Indeed potential is the key word here, it's not a nailed on severe event until a Red warning is enforced. So until that happens this event is not as bad as it can/could be.

     

    Also the reason why only Amber warnings were given for some flooding like you mentioned is because river flooding happens every year, I don't think it would be reasonable to issue a Red warning every time unless lives were at risk, some rivers don't endanger people that's common sense in a rural area where there's not a lot of people, but winds usually are more dangerous with slates flying off roofs etc. And I don't want a Red warning 4 days out either, ideally I will wait until Saturday or even later if that happens.

     

    ...."as says the Beaufort scale".

     

    Force 10 "Trees are broken off or uprooted, structural damage likely."

     

    Depends on the state of construction, something old or flimsy like a wood fence will break easily - doesn't take a rocket scientist to work that out, also smaller trees will get battered but older bigger trees with longer roots won't get uprooted unless the wind is 70-80mph but even then it depends. In the past we have had winds of 75-80mph but big old trees in a nearby field are still standing. If that was the case with 55mph winds Manchester would be treeless! lol

    Edited by Gaz1985
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    Posted
  • Location: Sowerby Bridge, West Yorkshire
  • Weather Preferences: Click on my name - sorry, it was too long to fit here......
  • Location: Sowerby Bridge, West Yorkshire

    I don't really understand that statement, considering the amber warning has the highest impact level (just a lower probability hence it's amber not red) there is definitely the potential for a severe event. Though the warning mentions gusts up to 80mph rather than 70mph.

     

     

    The 80mph is most likely across the channel islands, south facing coasts and the tip of Kent, GFS has here in gusts of around 60mph for example. Still, that's as we stand now, things could change rapidly with this sort of pattern.

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    Posted
  • Location: Maidstone
  • Location: Maidstone

    Beaufort wind force scale Specifications and equivalent speeds Beaufort wind scale Mean Wind Speed Limits of wind speed Wind descriptive terms Probable wave height in metres* Probable maximum wave height in metres* Seastate Sea descriptive terms Knots ms-1 Knots ms-1 0 0 0 <1 <1 Calm - - 0 Calm (glassy) 1 2 1 1–3 1-2 Light air 0.1 0.1 1 Calm (rippled) 2 5 3 4–6 2-3 Light breeze 0.2 0.3 2 Smooth (wavelets) 3 9 5 7–10 4-5 Gentle breeze 0.6 1.0 3 Slight 4 13 7 11–16 6-8 Moderate breeze 1.0 1.5 3–4 Slight–Moderate 5 19 10 17–21 9-11 Fresh breeze 2.0 2.5 4 Moderate 6 24 12 22–27 11-14 Strong breeze 3.0 4.0 5 Rough 7 30 15 28–33 14-17 Near gale 4.0 5.5 5–6 Rough–Very rough 8 37 19 34–40 17-21 Gale 5.5 7.5 6–7 Very rough–High 9 44 23 41–47 21-24 Severe gale 7.0 10.0 7 High 10 52 27 48–55 25-28 Storm 9.0 12.5 8 Very High 11 60 31 56–63 29-32 Violent storm 11.5 16.0 8 Very High 12 - - 64+ 33+ Hurricane 14+ - 9 Phenomenal

    *

     

     

    • These values refer to well-developed wind waves of the open sea.
    • The lag effect between the wind getting up and the sea increasing should be borne in mind.
    • To convert knots to mph multiply by 1.15, for m/s multiply by 0.514.

     

    Max of 55 knots X by 1.15 = 63.25 mph

     

    As per Met office Uk Paul quotes the rest from wiki 

     

    FYI I have found this topic very useful as i live in Kent lol

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

    I think that the stormy start to next week could be considered the very unpalatable transition of the weather pattern from the recent very mild/warm southerly dominated unsettled conditions that have almost had a summer plume feel about them at times, most especially in some southern parts, to a much more traditional mobile and zonal south west or westerly pattern.

     

    The models have handled these trend developments very consistently and accurately for some days now - even if the vigorous low has been, and still is the subject of uncertainty in terms of detail for the UK as a whole and which areas get most affected.

     

    This question is slowly but surely starting to get a little provisional consensus now and the rapid cyclogenesis of the wave feature in the atlantic looks increasingly likely to track SW-NE through England and Wales from late Sunday night and into Monday before exiting into the North Sea as a worryingly very potent small depression with severe weather associated with it on its southern flank.

     

    It looks at the moment as if the south eastern quadrant of the UK may bear the worst of this low based on the agreement so far of the models this evening..at least on the general track of the low.

     

    GFS,UKMO AND GEM 12z have broadly similar ideas - with minor differences in depth and exact track. But in these situations the micro detail becomes critical  to this small island which could mean the worst of the winds missing more of the south and south east, or conversely any slight adjustment northwards of the low brings larger areas into the path of the worst of the winds.

     

    Thereafter, the low swings away quickly away over the North Sea and into Scandinavia and a temporary ridge builds behind it before more unsettled weather arrives from the north west. No further stormy conditions are suggested to occur, but nonetheless it looks set for further wet and windy conditions to occur with the most unsettled conditions by this time further north west and, relative to the shocking conditions increasingly suggested to start the week, areas further south and east should see an improvement with perhaps some downstream ridging giving less unsettled and somewhat quieter weather by the 7 to 10 day period. But there is a lot (too much!!) weather to have to get through first of all before this happens, if it does.

     

    The ECM ensembles of this morning show reasonable agreement of the possibilities of rather higher pressure over the nearby continent from day 7 in an otherwise flat zonal pattern

     

    Posted Image

    Edited by Tamara תָּמָר
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    Posted
  • Location: Sowerby Bridge, West Yorkshire
  • Weather Preferences: Click on my name - sorry, it was too long to fit here......
  • Location: Sowerby Bridge, West Yorkshire

     

    ......

     

    As per Met office Uk Paul quotes the rest from wiki 

     

    FYI I have found this topic very useful as i live in Kent lol

     

    Tables never post properly!

     

    Actually I was quoting from the Royal Meterological Society, a bit better than wikipedia! Suggesting storm force for those areas I quoted with gusts up to hurricane force. That's got to be worth worrying about, surely.

     

    http://www.rmets.org/weather-and-climate/observing/beaufort-scale

    Edited by ukpaul
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    Posted
  • Location: Malton, North Yorkshire
  • Weather Preferences: Extreme weather - any kind!
  • Location: Malton, North Yorkshire

    All this red warning/amber warning talk is ridiculous. There is no way the Met Office would issue a red warning 4 days before the event! If they do decide this warrants a red warning it won't come until at least Sunday because the detail is too uncertain at this stage.

     

    We still need another 48 hours worth of runs before we can be more certain of the track of this low. It does look increasingly likely that it's going to cause at least some disruption somewhere. I expect it'll track a bit further south than the Met Office are currently predicting (at the moment saying the low centre will enter somewhere in SW England and exit around the Humber). Based on previous years lows like this tend to track up the channel or along the French coast, but as I say this could be different and more runs are needed to pinpoint the locations at highest risk of trouble.

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    Posted
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL
  • Weather Preferences: Dry/mild/warm/sunny/high pressure/no snow/no rain
  • Location: Droylsden, Manchester, 94 metres/308 feet ASL

    All this red warning/amber warning talk is ridiculous. There is no way the Met Office would issue a red warning 4 days before the event! If they do decide this warrants a red warning it won't come until at least Sunday because the detail is too uncertain at this stage.

     

    We still need another 48 hours worth of runs before we can be more certain of the track of this low. It does look increasingly likely that it's going to cause at least some disruption somewhere. I expect it'll track a bit further south than the Met Office are currently predicting (at the moment saying the low centre will enter somewhere in SW England and exit around the Humber). Based on previous years lows like this tend to track up the channel or along the French coast, but as I say this could be different and more runs are needed to pinpoint the locations at highest risk of trouble.

     

    Yep true, since this low emerged a number of days back it has tracked further and further south on the models, wouldn't surprise me if the strongest winds will be in Northern France, we shall see, still uncertainty with this.

    Edited by Gaz1985
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    Posted
  • Location: Maidstone
  • Location: Maidstone

    I agree with you ukpaul.  I was living in an old house when the 87 storm hit lost ridge tiles a rag stone garden wall and my curtains i had hung out to dry lol.  Having looked at the charts posted I am going to make sure that i take all precautions with this storm once bitten twice shy.

     

    I personally hope that the models are wrong and it downgrades.

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

    UKMO and GFS have the centre of the low in the south but NAVGEM has it over Scotland

     

    Posted Image

     

    GEM has the centre of the low developing way out east

     

    Posted Image

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

    970mb low from ECM this evening

     

    Posted Image

     

    UKMO and GFS to compare the big 3 at t96

     

    Posted ImagePosted Image

    Edited by Summer Sun
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