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Cold Spell Forecasts and Synoptic Forecast Discussion - 26/11/1020 onwards

  • 26-11-2010 7:49pm
    #1
    Registered Users Posts: 12,778 ✭✭✭✭ninebeanrows


    Please use this thread to discuss the medium term outlook for the Cold Spell and Detailed chart analysis.

    And use this one for more general Snow Reports & Chat.

    Good Luck:D;)


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Comments

  • Closed Accounts Posts: 1,530 ✭✭✭TheInquisitor


    Snow predicted on the north east and west coasts tonight. The Midlands and south/south west shouldn't see any snow.

    101pa.png

    A pool of very cold air over all of Ireland tomorrow and Sunday which would ensure any precipitation would be snow. Could be heavy at times over the weekend. There could also be a bit of a dumping on the far south east according to the models tonight.

    102lp.png

    For the 1st of december the cold has continued to say with us and has become much more pronounced. -8 uppers all over Ireland with pretty much all falls during the period of snow.

    103ds.png

    This doesn't sound like RAMMMMPPPPINNNNNNNGGGG does it?


  • Registered Users Posts: 245 ✭✭Artfu1Dodger


    The models seem to be droping the idea of a deep low pressure system coming up into south east england.
    Heres the GFS, UKMO and ECM at 120hrs.
    Keeps us in a very cold easterly wind well into next week.

    136608.png

    136610.gif

    136612.gif


  • Registered Users Posts: 5,946 ✭✭✭TheMilkyPirate


    That precipitation chart you posted is for an hour ago. The east and south east snow is not till later tonight and into the morning.

    In other news, That low feature that was missing from the latest GFS run was quite pronounced on the 6.1 news and weather, What's the reason for this i suppose it's them using different models. which one would that be based on?


  • Registered Users Posts: 99 ✭✭bkelly86


    Whats the chances of any snow making it as far as Laois over the weekend?


  • Closed Accounts Posts: 2,693 ✭✭✭Redsunset


    bkelly86 wrote: »
    Whats the chances of any snow making it as far as Laois over the weekend?

    Tomorrow morning looks best chance


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  • Registered Users Posts: 763 ✭✭✭F-Stop


    From previous thread

    Darkman2:
    Keep an eye on the M2 buoy for those in Dublin. We need the Dew Point out there (30km's east of Howth Head) to be BELOW 1C for snow to be realistic at coastal fringes. (The reason I don't say below zero is because of it's distance from land) Currently it is 1.1C having fallen .6C in the last hour. This will be crucial so Dubs should keep an eye on that.

    http://met.ie/latest/buoy.asp

    If the DP reaches within .5C of 0 on the buoy snow is a dead cert on immediate coasts.

    DP down to 0.1C now.


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


    Some info from the upstream 12Z Castor Bay, Lerwick, Albermarle and the 12Z and 18Z Valentia soundings.

    Castor Bay (Lough Neagh)

    T850:
    -7.9°C
    Thickness 500-1000: 5201m
    Thickness 850-1000: 1292m
    Steering Winds: Northerly 35-45kts

    Lerwick (Shetland Islands)

    T850:
    -9.1°C
    Thickness 500-1000: 5146m
    Thickness 850-1000: 1285m
    Steering Winds: Easterly 25kts

    Albermarle (Northeast England)

    T850:
    -7.5°C
    Thickness 500-1000: 5183m
    Thickness 850-1000: 1285dm
    Steering Winds: Northerly 20kts

    Valentia 12Z
    T850:
    -4.9°C
    Thickness 500-1000: 5244m
    Thickness 850-1000: 1300dm
    Steering Winds: NNW 30kts

    Valentia 18Z
    T850:
    -6.3°C
    Thickness 500-1000: 5244m
    Thickness 850-1000: 1302dm
    Steering Winds: Northerly 30kts

    The Albermarle sounding is the key one for the southeast tomorrow as it is most representative of conditions upwind. It's showing quite a moist profile, but it should lose some of this moisture through precipitation over land. Northeasterly flow will bring this airmass over Wales before coasting out over the Irish Sea. With the short sea track, it may not generate very heavy showers, but with less modification, they have a good chance of being snowy but shortlived.

    The Lerwick sounding is representative for the rest of the country tonight, and was slap bang in the middle of that "polar/non-polar low" system today. It's a similar profile to the Albermarle sounding, just slightly colder. There's a lot of high terrain between it and us, but a longer sea track by the Isle of mann when winds turn northeasterly tonight. So it should be generating streamers by the Isle of Mann and they shuold be directed southwestwards towards the east Coast, though I'd expect to see a clear slot in the lee of the Isle of Mann. Unfortunatley our friends in louth and north Meath may be in the wrong place again, like last year, with the northern Ireland landmass getting in the way too. From say east Meath south to Wexford should get the brunt of showery activity. SSTs are 12°C off the east coast, so showers will be beefy and likely thundery, but the big question remains what depth of melt layer there will be.

    Latest GFS sounding forecast for Dublin Airport 12Z tomorrow shows around a 1000ft warm layer, with positive surface wet bulb temperature, so hmmm, on the wrong side of marginal for snow, but the showers should make it further inland, so I'd expect snow at the surface there. Things will be improving all the while though, and the snowline will retreat back towards the coast tomorrow evening and night. I'd say most people will see snow, but there will be some unlucky ones who won't.

    Similarly for the northwest and west of the Shannon. Maybe by Roscommon, etc the showers from the north will have died out, but west of that shuld see sustained activity from the north Mayo coast. Plenty of places will see snow at all levels, but there will still be some dissapointed people at low levels, I would imagine.


  • Registered Users Posts: 174 ✭✭Defcol


    Su Campu wrote: »
    Unfortunatley our friends in louth and north Meath may be in the wrong place again, like last year, with the northern Ireland landmass getting in the way too.

    Awww crap!! :mad::mad: not again...boo urns


  • Registered Users Posts: 9,235 ✭✭✭lucernarian


    With humidity so low and no real convection taking place, the M2 buoy is really saying that there's some not very cold but dry air off the east coast. For showers to develop tonight, that air mass will have to change. This is expected to happen later tonight, so the humidity required for shower development will be in place. The wind direction will change to offer a larger sea fetch with resulting shower formation.

    The REAL problem with that reading is the air temperature, 5.7 degrees. As the wind direction changes, I want temperature to fall too. Unfortunately, for showers to happen there must be a decent sea fetch too. It will be a tall order to have more ENE winds over a fairly large area of water while also producing a drop in air temperature of about 3 degrees. I would want the air temperature to be below 4 degrees after it starts blowing from the ENE for a serious chance of snow along the costal parts of Dublin, Wicklow and Wexford.


  • Registered Users Posts: 347 ✭✭isle of man


    well if by chance we get anything tonight, be it hail or snow. it stick like **** to a shovel.

    its like a ice rink outside after the big thew today.


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  • Registered Users Posts: 542 ✭✭✭Squeaksoutloud


    Can anyone explain to me how the Hirlam precipitation graphic has plenty of convection coming in over the East over the weekend:

    http://www.dmi.dk/dmi/index/danmark/vejrkort.htm

    whereas the new Met Eireann one doesnt seem to have much at all?

    http://www.met.ie/forecasts/5day-ireland.asp

    Am I missing something here or which is likely...please be Hirlam!


  • Registered Users Posts: 1,523 ✭✭✭jambofc


    [QUOTE=Su Campu; though I'd expect to see a clear slot in the lee of the Isle of Mann. Unfortunatley our friends in louth and north Meath may be in the wrong place again, like last year[/QUOTE]

    what i was thinking but couldn't bring myself to say it,i dont think the showers are going to be heavy either(on the east coast),i think from what i can see it's after the weekend(late sunday night/into monday before most of meath see's any worthwhile snow.whats your input su on that?


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


    Can anyone explain to me how the Hirlam precipitation graphic has plenty of convection coming in over the East over the weekend:

    http://www.dmi.dk/dmi/index/danmark/vejrkort.htm

    whereas the new Met Eireann one doesnt seem to have much at all?

    http://www.met.ie/forecasts/5day-ireland.asp

    Am I missing something here or which is likely...please be Hirlam!


    HIRLAM stands for 'High Resolution Local area Model'. It can pick up on minute features that might spring up more readily than its parent model the ECMWF. Working with a combination of the two is usually the best job.


  • Registered Users Posts: 119 ✭✭kn2k10


    Defcol wrote: »
    Awww crap!! :mad::mad: not again...boo urns

    Hey, I live in Meath and we got snow today, North Meath infact

    So yay


  • Registered Users Posts: 542 ✭✭✭Squeaksoutloud


    Phew cos was worried that the six one news forecast this evening didnt show much precipitation on the charts. Anyway the roller coaster begins again just like last year! Put 3 new tyres on the jeep today so all set for the coming conditions!


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


    Another thread?!, jaysus , what did i miss?

    Temp: 0.3 o C
    Wind Chill : -2.4 o C
    D.p : -1.0 o C

    :)... its looking good once those temps stay down!


  • Registered Users Posts: 16,533 ✭✭✭✭nacho libre


    http://www.raintoday.co.uk/

    http://www.sat24.com/Region.aspx?country=gb&sat=ir&type=loop

    looks like plenty of activity for a while yet over the north west anyway:)


  • Registered Users Posts: 9,235 ✭✭✭lucernarian


    The HIRLAM model would be better at picking up small scale effects than a global forecast model like the one used for the 5 day forecasts. So showers generated by the Irish sea will show up better on HIRLAM than the one Met Eireann are using for their medium range forecast.

    But I feel that the actual wind direction and isobars will be subtly different to what HIRLAM predict. Mainly because the LP in the channel is not retrogressing (moving westwards) as i'd like it to, if it's even moving westwards at all. The main brunt of the precipitation tonight will be Co. Dublin and southwards. But for Dublin, I think any precipitation will be light until we're closer to dawn.


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


    http://www.raintoday.co.uk/

    http://www.sat24.com/Region.aspx?country=gb&sat=ir&type=loop

    looks like plenty of activity for a while yet over the north west anyway:)

    Mostly rain here this last 2 hours. Temps don't seem to be as low as expected.


  • Moderators, Science, Health & Environment Moderators Posts: 16,668 Mod ✭✭✭✭Gonzo


    not a good forecast there on RTE for counties Louth and Meath. Looks like the Isle Of Man is gonna kick us in the teeth yet again. Looks like the North West is the place to be for snow over the weekend and then Wexford, Wicklow and South Dublin getting most of the Irish Sea snow.


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  • Moderators, Science, Health & Environment Moderators Posts: 4,466 Mod ✭✭✭✭mickger844posts


    Temp has stalled here at 1.1c due to the wind from the NW picking up to 11km/h. DP -0.5


    More Detail @ www.waterfordcityweather.com

    http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=IWATERFO4


  • Registered Users Posts: 191 ✭✭carlmwan


    Gonzo wrote: »
    not a good forecast there on RTE for counties Louth and Meath. Looks like the Isle Of Man is gonna kick us in the teeth yet again. Looks like the North West is the place to be for snow over the weekend and then Wexford, Wicklow and South Dublin getting most of the Irish Sea snow.

    what :mad: how?


  • Closed Accounts Posts: 2,667 ✭✭✭WolfeIRE


    I would not despair if I were living anywhere near the east coast.

    The HIRLAM model best illustrates where snow will fall over the next 72 hrs. Select Nedbor after clicking on this linkmost of the heaviest precip will fall before dawn with showers retreating to eastern coastal areas by late morning.


  • Moderators, Science, Health & Environment Moderators Posts: 16,668 Mod ✭✭✭✭Gonzo


    carlmwan wrote: »
    what :mad: how?

    The short sea-track between us and Isle of Man is preventing showers to develop and we will mostly escape with a dry, sunny and frosty weekend. Dublin southwards will have lots of showers because of a much larger sea track with room for showers to develop.It happened all last winter and looks like it's gonna happen again over the next 2 days at least. Hope im wrong tho.


  • Registered Users Posts: 191 ✭✭carlmwan


    Gonzo wrote: »
    The short sea-track between us and Isle of Man is preventing showers to develop and we will mostly escape with a dry, sunny and frosty weekend. Dublin southwards will have lots of showers because of a much larger sea track with room for showers to develop.It happened all last winter and looks like it's gonna happen again over the next 2 days at least. Hope im wrong tho.

    ah and i was getting excited..i got snow last year not much like 2-3 inches tho




  • WolfeIRE wrote: »
    I would not despair if I were living anywhere near the east coast.

    The HIRLAM model best illustrates where snow will fall over the next 72 hrs. Select Nedbor after clicking on this linkmost of the heaviest precip will fall before dawn with showers retreating to eastern coastal areas by late morning.
    I don't think met eireann or eveyln clicked on that link...going on her 930 forecast


  • Registered Users Posts: 295 ✭✭Winger_PL


    The 3hr met.ie charts have the precip touching the coast at Dublin Bay. Interestingly, the also do show the 'polar low / non-polar low' feature as an actual low.

    I don't think there's any point in doing a night watch for us on the east cost thought, I don't think there will be any significant precip until 4-5am.


  • Registered Users Posts: 16,533 ✭✭✭✭nacho libre


    think it could be picture time. a really decent dusting now!!


  • Registered Users Posts: 1,789 ✭✭✭BEASTERLY


    temp: -1.4c
    dewpoint: -3.0
    Wind is picking up, but still NNW, waiting for that W to change to E


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  • Registered Users Posts: 1,523 ✭✭✭jambofc


    think it could be picture time. a really decent dusting now!!

    go for it nacho,cheers us all up over this side of the country


This discussion has been closed.
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