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Model output discussion - here comes the beast!


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Early guidance forewarning of next weeks weather was issued earlier on, and this has been further enhanced with extended outlooks in bulletins. AFAIK (comms not being my area) public agencies and majo

Come on those looking for the breadown before the major cold and snow has begun You will be very lucky if that is the correct word to see this in ANY winter in the rest of your lives I would sugg

Microscale detail absorbing an awful lot of attention on here, when in reality it is a waste of emotion. The macroscale pattern is now fixed - it will not change significantly now for the start of nex

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Posted
  • Location: Saffron Walden, Essex
  • Weather Preferences: Warm summers, Snowy winters.
  • Location: Saffron Walden, Essex

    Looking at the Arpege precipitation chart for Tuesday shows showers coming in from a NE direction, not directly East whereas on Wednesday it does look more Easterly (maybe that`s when the true term actually starts).

    Anyway...

    arpege-42-80-0.png?24-04

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    Posted
  • Location: Cheltenham, Gloucs.
  • Location: Cheltenham, Gloucs.
    14 minutes ago, MattStoke said:

    Snow won't melt with air temperatures and dew points below freezing. It's heat that melts snow, not sunlight. Otherwise mountain regions thousands of miles south of the UK would never have snow cover.

    To add my stamp of approval  on this post: Sunshine melts snow? Hmmm. So, that happens daily on the ski slopes then? Snow has a strong libido. It is air temps that melt snow and air temps can be warmed by sunshine, however, where we know that air temps remain at or below zero, there is little chance of snow melt. At most, it might sublimate. 

    Edited by EllyTech
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    Posted
  • Location: Truro
  • Weather Preferences: Cold
  • Location: Truro

    From what I have learned from the years I have browsed this forum, with the cold already in place for a few days I am less worried about the channel low than I would be. I would expect it to run out of oomph and flatten against the cold air a little and possibly veer west or just rotate around back down South West. It is also very difficult for the models to nail down the actual track until within 24Hrs? If it stays in the channel then its likely I wont be able to post for a while as I will have no electricity :)  The classic snow events in the past for the South west mostly occurred during breakdowns in the cold where systems from the Atlantic bumped into cold air over the SW and buried it, this is somewhat different. Is it not possible that most of the media is holding back on warnings about snow as they too are unsure about this feature? e.g. BBC?

    Interesting next few days:yahoo:

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    Posted
  • Location: Saffron Walden, Essex
  • Weather Preferences: Warm summers, Snowy winters.
  • Location: Saffron Walden, Essex

    @TEITS Glad I wasn`t going mad, we pretty much agree regarding direction.

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    Posted
  • Location: Cheltenham, Gloucs.
  • Location: Cheltenham, Gloucs.
    15 minutes ago, Stuie W said:

    Looking at the Arpege precipitation chart for Tuesday shows showers coming in from a NE direction, not directly East whereas on Wednesday it does look more Easterly (maybe that`s when the true term actually starts).

    Anyway...

    arpege-42-80-0.png?24-04

    Agree that, if the signal is there, there's a chance anywhere.

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

    ICON 06z out

    icon-0-96.png?24-06   icon-0-120.png?24-06

    icon-1-96.png?24-06   icon-1-120.png?24-06

    This run is perfectly placed to drag that low over Northern France and keep the UK colder later on as we see heights begin to lower to our north east. 

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    Posted
  • Location: Nr Chelmsford, Essex
  • Weather Preferences: Hurricanes, Thunderstorms and blizzards please!
  • Location: Nr Chelmsford, Essex
    22 minutes ago, TheBeastFromTheEAST said:

    Big thanks to Net Weather by the way ?

    Spot on Beast.  Just want to reiterate this, Netweather and the mods provide us strange weather obsessives the best place on the internet to share our passion and draws in some great posters who help improve our grasp of all things weather.  When the site crashed the other day I didn't know what to do with myself.  Thanks mods, sending you all a virtual pint. 

    I better get back on topic quick, errr, today's ECM is one of the best NWP runs for the UK, like ever!

    120 hours is magnificent

    ECH1-120.GIF?24-12 

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    Posted
  • Location: Runcorn, Cheshire
  • Weather Preferences: Snowy winters, hot, sunny springs and summers.
  • Location: Runcorn, Cheshire
    21 minutes ago, MattStoke said:

    Snow won't melt with air temperatures and dew points below freezing. It's heat that melts snow, not sunlight. Otherwise mountain regions thousands of miles south of the UK would never have snow cover.

     

    8 minutes ago, EllyTech said:

    To add my stamp of approval  on this post: Sunshine melts snow? Hmmm. So, that happens daily on the ski slopes then? Snow has a strong libido. It is air temps that melt snow and air temps can be warmed by sunshine, however, where we know that air temps remain at or below zero, there is little chance of snow melt. At most, it might sublimate. 

    It’s actually sort of complicated as there are many factors that go into the melt rate given snow depth and the ambient temperature:

    • The age of the snow — Older snow has a lower albedo, which means it absorbs more energy from the sun as opposed to reflecting it.
    • Terrestrial Radiation — Emitted by the clouds and sky, snow absorbs almost 100% of that energy even at temperatures below freezing.
    • The surface — Snow will melt faster on dense surfaces like roads, driveways and sidewalks that slowly absorb and release the sun’s energy. Less dense materials, like wood, do not absorb as much energy. The color of the surface also matters, as different colors absorb/reflect at different rates.
    • Latent heat transfer — The latent heat created by evaporation is transferred to the snow as moisture sublimes out of the air.

    The melting is not purely related to the temperature, but to the energy the sun bombards us with and the above factors.

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    Posted
  • Location: Royston , Herts
  • Weather Preferences: SNOW
  • Location: Royston , Herts
    3 minutes ago, Captain Shortwave said:

    ICON 06z out

    icon-0-96.png?24-06   icon-0-120.png?24-06

    icon-1-96.png?24-06   icon-1-120.png?24-06

    This run is perfectly placed to drag that low over Northern France and keep the UK colder later on as we see heights begin to lower to our north east. 

    Wow swathes of -16 850s on the icon ??

    Edited by ICE COLD
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    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
    37 minutes ago, Summer Sun said:

    UKMO extended has a nasty looking low moving up from the south-west that coupled with winds from the east could deliver significant amounts of snow quite widely

    ukm2.2018030300_168_lant.troplant_prp_fcst.gentracker.thumb.png.25e8478e9cbb0a2dc7889b78fc090f58.png

    Hmmm again more GFS like. Two runs in a row. Massive snowfall for many but dodgy for the SE. 

    But this is still a long long way out in the circumstances.

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    Posted
  • Location: Royston , Herts
  • Weather Preferences: SNOW
  • Location: Royston , Herts

    Are we really having discussions regarding snow melt ,come on guys we have like the best charts ever. ?

    Icon looking good ? 

    GFS 6z out to T48 . Yes this at just T48 .STUNNING. 

    IMG_1781.PNG

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    Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire
    4 minutes ago, warrenb said:

    Can't believe people are looking at models for streamers. These things can setup with an hours notice

    Very true to a certain extent. However we can use the models to see the general flow of the E,ly that is being predicted. For example I know for a fact a wash streamer will not develop from a direct E,ly or ESE,ly. I require a ENE,ly or NE,ly. I also know that if the flow does veer towards a ESE,ly then this favours those locations with a longer sea fetch across the N Sea  and places such as Kent are likely to be drier.

    Don't forget there is a difference between bands of snow showers and a streamer. These often get mixed up on this forum.

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    Posted
  • Location: Orpington Kent
  • Weather Preferences: Snow freezing rain heat waves
  • Location: Orpington Kent

    The whole country under snow more  persistent snow in south very strong easterly flow  Northern England Scotland heavy snow showers banding in longer outbreaks of snow ..:yahoo::yahoo::yahoo::cold::cold:

    401938CE-0B4B-472E-98B8-D1C774561708.png

    Edited by abbie123
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    Posted
  • Location: Nr Chelmsford, Essex
  • Weather Preferences: Hurricanes, Thunderstorms and blizzards please!
  • Location: Nr Chelmsford, Essex
    1 minute ago, Man With Beard said:

    Hmmm again more GFS like. Two runs in a row. Massive snowfall for many but dodgy for the SE. 

    But this is still a long long way out in the circumstances.

    Whilst it does look a little like the GFS, given this mornings ECM is apparently aligned to Mogreps along with the overnight Met update, I think the ECM option maybe  slightly favoured  *currently*.  

    Onto the GFS, and this is only 60 hours away

    gfsnh-0-60.png?6 gfs-1-60.png?6

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    Posted
  • Location: Liphook
  • Location: Liphook
    2 minutes ago, Summer Sun said:

    GEM ends with a southerly but it is still cold for the majority

    234_mslp850.thumb.png.f35638d27a2b9790db337b850493ab1d.png234_uk2mtmp.thumb.png.9e33f16c578f786978dc5cb77d92d359.png

    That just goes to show how entrenched the cold air is at the surface. 

    Usual 850hpa rules don't apply here guys. Even 0C at 850hpa will probably still be snow at the surface in this type of set-up.

    06z GFS running, lets see how it evolves the situation.

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    Message added by Paul

    Please only post model discussion in this thread 

    For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
    https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

    For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
    https://www.netweather.tv/forum/forum/142-regional-discussions/

    We also have a special post SSW cold spell discussion open here:
    https://www.netweather.tv/forum/topic/89358-ssw-related-cold-spell-will-it-wont-it/

    Thank you!

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