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Wintry spell forecasting discussion - 25/11/2010 onwards

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  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    Regarding the question of why it snowed at sea level in Wicklow this morning, I think it may be due to the fact even the coast was affected by an offshore flow off the cold land, the opposite to a sea breeze. This layer of cold air must have been deep enough to prevent melting.

    WindDirectionHistory.gif

    10112509_2_2506.gif

    The showers were being steered by upper winds, roughly 850-700hPa, which were just slightly east of due north, which would steer them ever so slightly onshore. But with the backing wind in the cold low-level layer, this would have stopped melting.

    10112509_2_2506.gif


    This northerly flow turns more easterly over the weekend and will therefore advect a marine layer over eastern coastal regions, as opposed to this cold land layer. This will make a big difference with melt layers, and I'd be extremely surprised to see any snow inthe same location come Saturday or Sunday.


  • Registered Users Posts: 12,778 ✭✭✭✭ninebeanrows


    Su Campu wrote: »
    Regarding the question of why it snowed at sea level in Wicklow this morning, I think it may be due to the fact even the coast was affected by an offshore flow off the cold land, the opposite to a sea breeze. This layer of cold air must have been deep enough to prevent melting.

    This northerly flow turns more easterly over the weekend and will therefore advect a marine layer over eastern coastal regions, as opposed to this cold land layer. This will make a big difference with melt layers, and I'd be extremely surprised to see any snow inthe same location come Saturday or Sunday.

    Thanks for the explanation.

    I'll take you up on that and say you're definitely wrong and that there will be snow in Arklow & surroundings this weekend.:D;)

    I don't know what you're grounding your assertion on? I accept at times things may become marginal at peak temperature during the day etc. But i would have almost put it near 90% that there will be snow falling right on the coast.


  • Registered Users Posts: 12,778 ✭✭✭✭ninebeanrows


    Looking on the raintoday runs , it looks like a lot of the east cost will see sleet this evening with the Dublin and Wicklow Mts area getting snow,

    Even in the newbridge area where I am it more so looks like , well they class it as rain/snow I am going to call it sleet .

    Am I allowed to post up images from raintoday.co.uk?

    They give a brilliant precip analysis and time scale too

    I can't see much wintry stuff from this front unless it peps up. Maybe on higher routes in Wicklow.


  • Registered Users Posts: 3,516 ✭✭✭irish1967


    DominoDub wrote: »


    Winger and Iancar on another expedition???


  • Registered Users Posts: 2,677 ✭✭✭Rougies


    irish1967 wrote: »
    Winger and Iancar on another expedition???

    I doubt either of them would hide from the helicopter in a wooded area while waiting to be rescued!


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  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    Thanks for the explanation.

    I'll take you up on that and say you're definitely wrong and that there will be snow in Arklow & surroundings this weekend.:D;)

    I don't know what you're grounding your assertion on? I accept at times things may become marginal at peak temperature during the day etc. But i would have almost put it near 90% that there will be snow falling right on the coast.

    There is no day or night over the sea, marine air temperatures at this time of the year don't show much diurnal variation, so if there's a strong enough onshore breeze this should overcome any night time land cooling near the coast.

    It is of course a bit different inland, but we're talking about the coast here, right?! :D


  • Registered Users Posts: 5,068 ✭✭✭Iancar29


    Haha, don't worry people, it wasn't us, clearly us being weather addicts we'd know what to expect and would hav more safety measures taken , for example we would've let fellow boardsies know wer we wer goin .

    Plus ... We both hav gps on our phones .
    But I DID ask him jokingly if he had snow chains at the ready ha :D


  • Registered Users Posts: 6,012 ✭✭✭TheMilkyPirate


    When you all talk about the coast what exactly do you all mean? do you mean the beach (or where the beach would be) or a few miles inland?


  • Closed Accounts Posts: 311 ✭✭forkassed


    Su Campu wrote: »
    There is no day or night over the sea, marine air temperatures at this time of the year don't show much diurnal variation, so if there's a strong enough onshore breeze this should overcome any night time land cooling near the coast.

    It is of course a bit different inland, but we're talking about the coast here, right?! :D

    What do you think of the GFS charts for Friday Night into saturday morning? Wind looks slack enough not to modify temps and snow showers could pepper the East Coast.



    Rtavn362.png

    Rtavn369.png


  • Registered Users Posts: 11,134 ✭✭✭✭maquiladora


    National Forecast



    25 November 2010 16:18

    Today

    Becoming mostly cloudy this evening and early tonight with outbreaks of rain or sleet in northern areas extending southwards with the risk of some snow on higher ground in parts of east Ulster and Leinster. Clearer and drier weather will follow with frost and icy patches developing before morning as skies clear. The lowest temperatures will range from +3 to -3 degrees.


    Tomorrow

    Tomorrow the frost and ice will clear in the morning and most places will have another dry day with good sunny spells. However, wintry showers will occur in northern and western counties, with a risk of isolated thunderstorms near coasts and some snow on high ground. The top temperatures will only be between 2 and 6 degrees in a moderate north to northwest wind.


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  • Registered Users Posts: 12,778 ✭✭✭✭ninebeanrows


    baraca wrote: »
    When you all talk about the coast what exactly do you all mean? do you mean the beach (or where the beach would be) or a few miles inland?

    Well i would talk about my location as being on the coast! Which is about 750 metres from the sea at 22m ASL.:D


  • Closed Accounts Posts: 292 ✭✭roryc1


    Hey Su, how far inland would you think snow could fall, under the forecast conditions we have coming over the next few days?


  • Registered Users Posts: 14,514 ✭✭✭✭M.T. Cranium


    The 12z GEM (CMC) falls in line with the 12z GFS on the strong low in northern France by Tuesday. In fact, the low on that model is even stronger at 967 mbs. All eyes on the other major models now to see how much consensus there is at this early stage. A low this strong would have the b-word in play for large parts of the U.K. and Ireland. But must stress this development is far from a certain outcome at this stage. It would be almost unprecedented too, coming from a source west of Iberia. The storm of 31 Dec 78 into 1 Jan 79 came from more of a westerly source but the setups at storm time would be similar.

    Before that stage is reached, would generally suggest that snowfall through the weekend will be patchy and a case where some places get a nice coating, others get very little and there are various mixtures in play as well, including some hail which in some cases falls as snow pellets -- this can be counted as snow if you like, but you don't have to shovel it away, just watch it bounce. :D


  • Posts: 0 [Deleted User]


    Thanks for the explanation.

    I'll take you up on that and say you're definitely wrong and that there will be snow in Arklow & surroundings this weekend.:D;)

    I don't know what you're grounding your assertion on? I accept at times things may become marginal at peak temperature during the day etc. But i would have almost put it near 90% that there will be snow falling right on the coast.
    I disagree with su campu also.The wind close to those showers this morning was nne not north and flowed in off the sea
    Those were the actual local conditions here.
    North at the wicklowweather site that you posted by the way [mothman] is directly a sea breeze in his location which usually rises his temperature but clearly not enough to prevent snow on this occasion :)
    Snow was also observed by trogdor to be falling to the sea off bray-that could have been hail but going on what mm had further south was probably snow.
    As regards Arklow having rain next saturday and sunday and next week...Su campu you're clearly off your trolley :D


  • Closed Accounts Posts: 5,550 ✭✭✭Min


    Part of the UK's met office weather warning for Friday: Spells of snow may affect parts of Wales, southwest England and Northern Ireland, especially over higher ground where accumulations of 2-5cm are possible.


  • Registered Users Posts: 6,012 ✭✭✭TheMilkyPirate


    I'll take wexford town as an example (not because i live there obviously.) to see what you all think, I get confused sometimes as to wether i'm technically on the coast or a a good few miles inland when there is a *north easterly* wind blowing. Take a look at my intricate map here that i created where i've tried to illustrate what i'm getting at. If the wind was blowing straight easterly it would to come through the harbour so technically i'd only be about 2 to 3 miles form the coast BUT if it was coming in a north easterly direction it would have to blow over curracloe screen etc meaning i would be at least 20 to 30 miles inland. Correct??

    th.a491cbf98b.gif


  • Posts: 0 [Deleted User]


    It would be blowing over land yes but caressing the coast.
    None of the landmass it would blow over would be far from the coast.
    So coastal temps abound


  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    I disagree with su campu also.The wind close to those showers this morning was nne not north and flowed in off the sea
    Those were the actual local conditions here.
    North at the wicklowweather site that you posted by the way [mothman] is directly a sea breeze in his location which usually rises his temperature but clearly not enough to prevent snow on this occasion :)
    Snow was also observed by trogdor to be falling to the sea off bray-that could have been hail but going on what mm had further south was probably snow.
    As regards Arklow having rain next saturday and sunday and next week...Su campu you're clearly off your trolley :D

    Oops, I confused Arklow for Ashford! But in any case, if you say it was a NNE wind, that's still not a sea breeze!

    136432.png

    I still believe it was some mesoscale setup that caused the snow, as I can't see how it was cold enough otherwise. And are you sure it was snow and not hail that was falling out to sea off Bray? Difficult to tell from a distance. Hail will survive the melt layer better. But hey, if I'm wrong I'm wrong, no big deal! My livelyhood doesn't depend on it so I can afford to be wreckless! :D


  • Closed Accounts Posts: 5,150 ✭✭✭Deep Easterly


    baraca wrote: »
    I'll take wexford town as an example (not because i live there obviously.) to see what you all think, I get confused sometimes as to wether i'm technically on the coast or a a good few miles inland when there is a *north easterly* wind blowing. Take a look at my intricate map here that i created where i've tried to illustrate what i'm getting at. If the wind was blowing straight easterly it would to come through the harbour so technically i'd only be about 2 to 3 miles form the coast BUT if it was coming in a north easterly direction it would have to blow over curracloe screen etc meaning i would be at least 20 to 30 miles inland. Correct??

    th.a491cbf98b.gif

    Hey Baraca,

    How did you get that image to be small and clickable? I think this would be a great tool to use when posting up charts as it would take up less space :)


    DMI HIRLAM suggesting that some showers will filter down through Connaght from Donegal tomorrow evening and night:

    136433.gif


    could bring some snow flurries for us in Mayo/Roscommon/Galway if it works out anything like that. :)


  • Closed Accounts Posts: 5,234 ✭✭✭thetonynator


    Heating on full blast and the house is bloody freezing!

    Very little chance of snow here, too far inland for any showers to make it here really, definately no accumulations above 1 to 2 cm unless something happens to change the forecast early next week. . .


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  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    Heating on full blast and the house is bloody freezing!

    Very little chance of snow here, too far inland for any showers to make it here really, definately no accumulations above 1 to 2 cm unless something happens to change the forecast early next week. . .

    No accumulations above 1-2cms??? That's pretty much sea level!!! :pac:


  • Registered Users Posts: 391 ✭✭Sonovagun


    Raining in east Meath. Very cold though.


  • Registered Users Posts: 6,012 ✭✭✭TheMilkyPirate


    Just used this site deep and when you upload the image just choose the thumbnail code :)


  • Registered Users Posts: 251 ✭✭dbyrne


    heaviest November snowfall for 17 years in the UK according to sky weather, some great pics via the red button , while they are sending us the billions of euros could they not push a bit of snow our way also.

    You think you have it bad, I had the heating on all night and our front bedroom only got to 17.2C and this is after I have just reinsulated the attic with another 150mm of insulation, 300mm in total, you would swear I had left a bloody window open.


  • Registered Users Posts: 16,846 ✭✭✭✭nacho libre


    Hey Baraca,

    How did you get that image to be small and clickable? I think this would be a great tool to use when posting up charts as it would take up less space :)


    DMI HIRLAM suggesting that some showers will filter down through Connaght from Donegal tomorrow evening and night:

    136433.gif


    could bring some snow flurries for us in Mayo/Roscommon/Galway if it works out anything like that. :)

    yr.no is showing snow for me tomorrow. although met eireann are still sticking to snow for high ground only. i guess we'll just have to wait and see- unless you have a time machine, do you?


  • Registered Users Posts: 2,310 ✭✭✭Trogdor


    Su Campu wrote: »
    Oops, I confused Arklow for Ashford! But in any case, if you say it was a NNE wind, that's still not a sea breeze!

    https://us.v-cdn.net/6034073/uploads/attachments/288533/136432.png

    I still believe it was some mesoscale setup that caused the snow, as I can't see how it was cold enough otherwise. And are you sure it was snow and not hail that was falling out to sea off Bray? Difficult to tell from a distance. Hail will survive the melt layer better. But hey, if I'm wrong I'm wrong, no big deal! My livelyhood doesn't depend on it so I can afford to be wreckless! :D

    Can't say for sure that it wasn't hail no, one very big indicator i would use would be the dp off the sea as in the past in my experience anyway, when a sea breeze kicks up things generally become very marginal and it can ruin everything here but if the dp is negative out to sea then there is a much better chance of seeing at least falling snow here. Gfs has the dp negative over the irish sea and most of ireland for most of the weekend (with a few exceptions) so i am certainly hopeful at least of seeing plenty of falling snow here although i would expect to see sleet and possibly rain at times too over the weekend. Dp at the M2 buoy in the Irish sea is currently -1.4C


  • Closed Accounts Posts: 5,150 ✭✭✭Deep Easterly


    yr.no is showing snow for me tomorrow. although met eireann are still sticking to snow for high ground only. i guess we'll just have to wait and see- unless you have a time machine, do you?

    Nope but I am working on it! :p. I want to go back to 63 or 47 to see what they were really like first hand!

    Yeah, high ground will always be more favoured but maybe dp's might be just low enough to maybe scrape a few flakes should those forecast showers make it down. If you do get a few flurries tomorrow evening Nacho, spare enough for me before you fling the leftovers down this way. :)


  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    trogdor wrote: »
    Can't say for sure that it wasn't hail no, one very big indicator i would use would be the dp off the sea as in the past in my experience anyway, when a sea breeze kicks up things generally become very marginal and it can ruin everything here but if the dp is negative out to sea then there is a much better chance of seeing at least falling snow here. Gfs has the dp negative over the irish sea and most of ireland for most of the weekend (with a few exceptions) so i am certainly hopeful at least of seeing plenty of falling snow here although i would expect to see sleet and possibly rain at times too over the weekend. Dp at the M2 buoy in the Irish sea is currently -1.4C

    Well, I guess it's a waiting game! I hope you get a foot of snow but, eeeerrr, I think that's not going to happen! :D


  • Registered Users Posts: 16,846 ✭✭✭✭nacho libre


    Nope but I am working on it! :p. I want to go back to 63 or 47 to see what they were really like first hand!

    Yeah, high ground will always be more favoured but maybe dp's might be just low enough to maybe scrape a few flakes should those forecast showers make it down. If you do get a few flurries tomorrow evening Nacho, spare enough for me before you fling the leftovers down this way. :)

    let me know when you have it up and running i'd like to go back and experience those epic winters as well. although it won't be quite the same without the boards.ie weather forum to post on:pac:

    i'll do my best to send any snow on to you, just as long as senor Pangea doesn't keep it all for himself up in Donegal. he's selfish that way.


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  • Registered Users Posts: 11,134 ✭✭✭✭maquiladora


    Its good to debate our thoughts on what we think will happen.

    If we didn't disagree on our opinions of what might be in store and instead just kept silent while waiting for whatever happens to happen, then that would make a very boring thread... :)

    So with that said...Im expecting dry, cold conditions here with some sleet/rain next week. :p


This discussion has been closed.
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